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Vulnerability of baobab species to climate change and effectiveness of the protected area network in Madagascar: Towards new conservation priorities
... Several analyses have provided examples of species likely to suffer range reductions in the twenty-first century 16,18 . For example, Vieilleident et al. 27 predicted that the Malagasy baobab Adansonia suarezensis is likely to go extinct before 2080 owing to an overall loss in suitable habitat. Changes in range size have usually been assessed by considering the climatic characteristics of current distributions and the projected distribution of these climatic conditions in future 27,28 . ...
... For example, Vieilleident et al. 27 predicted that the Malagasy baobab Adansonia suarezensis is likely to go extinct before 2080 owing to an overall loss in suitable habitat. Changes in range size have usually been assessed by considering the climatic characteristics of current distributions and the projected distribution of these climatic conditions in future 27,28 . However, vulnerability might be exacerbated by other factors, including biotic interactions, reduced adaptive evolutionary response and dispersal ability. ...
... Species' distribution can be presence-only data 17,22 , presence/absence 50 or abundance observations 51 , based either on fieldwork or specimen records 22,52 . Correlative models have been applied to species at scales ranging from local to global 19,53 ( Fig. 1), and have been widely used to explore the vulnerability of vertebrates (including birds 36,52,54 , mammals 17,28,38 , amphibians 30,50 and fishes 22,55 ), invertebrates 14,56,57 and plants 27,58 . ...
The effects of climate change on biodiversity are increasingly well documented, and many methods have been developed to assess species' vulnerability to climatic changes, both ongoing and projected in the coming decades. To minimize global biodiversity losses, conservationists need to identify those species that are likely to be most vulnerable to the impacts of climate change. In this Review, we summarize different currencies used for assessing species' climate change vulnerability. We describe three main approaches used to derive these currencies (correlative, mechanistic and trait-based), and their associated data requirements, spatial and temporal scales of application and modelling methods. We identify strengths and weaknesses of the approaches and highlight the sources of uncertainty inherent in each method that limit projection reliability. Finally, we provide guidance for conservation practitioners in selecting the most appropriate approach(es) for their planning needs and highlight priority areas for further assessments.
... target species would persist (Hole et al. 2009), or extinction rates would be lower inside protected areas under warming scenarios (D'Amen et al. 2011;Klorvuttimontara et al. 2011;Popescu et al. 2013;Virkkala et al. 2014). However, other studies have found that protected areas would fail to achieve conservation objectives under climate change and project large extinction rates both inside and outside protected areas (Aragón et al. 2010;Kharouba and Kerr 2010;Bagchi et al. 2013;Leach et al. 2013;Velásquez-Tibata et al. 2013;Vieilledent et al. 2013;Ferro et al. 2014;Scriven et al. 2015). ...
... Additionally, most climate change and protected area studies have been conducted in the extra-tropics with only a few studies examining tropical forest ecosystems (e.g., Klorvuttimontara et al. 2011;Bagchi et al. 2013, Velásquez-Tibata et al. 2013Vieilledent et al. 2013;Ferro et al. 2014;Scriven et al. 2015). Of these, far fewer have been conducted in tropical Asia (Klorvuttimontara et al. 2011;Scriven et al. 2015) despite its high biodiversity value and the increasingly large conservation threats region-wide (Sodhi et al. 2004). ...
... Our results are largely in agreement with previous protected areas effectiveness evaluations in other tropical systems which have highlighted the importance of considering warming impacts (Bagchi et al. 2013;Velásquez-Tibata et al. 2013;Vieilledent et al. 2013;Ferro et al. 2014). The buffering capacity of refuges (protected areas) from climate change will depend upon the heterogeneity of available microclimates (Sears et al. 2011;Bonebrake and Deutsch 2012) and the focal community characteristics (Voigt et al. 2003). ...
Protected areas are important in conserving the rapid decline of biodiversity in the Anthropocene. Yet
uncertainty persists whether protected areas will continue to meet conservation goals if climate change causes community or ecosystem shifts. Previous research has proven equivocal with some studies finding protected areas fail conservation objectives and others finding objectives are largely met. The effectiveness of protected area systems
within tropical Asia and for insects are particularly understudied. Using species distribution modeling of 68 butterfly species (15,346 locality records), we carried out an evaluation of the effectiveness of protected areas in Hong Kong, one of the most well-covered (40% land area) protected area systems in the Asian tropics, and projected how the ability to protect biodiversity would change under different climate change scenarios and different conservation target schemes. Under climate change, 15–37% of the modeled species in 2000 were projected to become extirpated by 2050. Under all conservation target schemes, the proportion of species unprotected increased or leveled, by up to as much as 7%. If buffer grids were considered as unprotected, the increase in these gap species was much greater, by up to as much as 22%. These results together indicate that under climate change, the effectiveness of protected areas for butterflies in Hong Kong is likely to decrease despite the territory’s relatively high proportion of protected area coverage. We also highlight here the importance of the fortification of partly protected areas in mediating biodiversity loss under the impacts of global change.
... A primary goal of these areas is to buffer species from these historical drivers of species decline (Monzón et al. 2011) and long-term impacts, such as climate change (Ferro et al. 2014;Scarano and Ceotto 2015;Caten et al. 2017). Climate change potentially requires species to shift their range to track suitable habitats (Vieilledent et al. 2013;Foden et al. 2019). This potential range shift may occur beyond the existing limits of the protected area network (Parmesan 2006;Vieilledent et al. 2013), influencing the protected area's effectiveness in conserving biodiversity. ...
... Climate change potentially requires species to shift their range to track suitable habitats (Vieilledent et al. 2013;Foden et al. 2019). This potential range shift may occur beyond the existing limits of the protected area network (Parmesan 2006;Vieilledent et al. 2013), influencing the protected area's effectiveness in conserving biodiversity. Chape et al. (2005) defined the extent of biodiversity distribution within protected areas as a metric to evaluate their effectiveness. ...
... Sensitivity is the ratio of correctly predicted presences to the total number of presences, while Specificity is the ratio of correctly predicted absences to the total number of absences. The AUC varies from 0 to 1, and values > 0.9 indicate highly accurate capacity (Thuiller et al. 2009;Vieilledent et al. 2013;Wilson et al. 2019). TSS varies from − 1 to + 1, with 0 values indicating random previsions. ...
One of Brazil’s most threatened tropical biome is the Atlantic Forest. This biome has distinct forest formations, as the Araucaria Mixed Forest, a sub-tropical ecosystem distributed through southern and southeastern Brazil, surrounded by Dense Ombrophilous Forest. The defining tree species of Araucaria Mixed Forest is Araucaria angustifolia (known as Araucaria), an endangered, relict, and historically managed conifer. Due to unsustainable exploitation during the twentieth century, the main strategy for Araucaria preservation was the creation of protected areas. However, protected areas’ coverage within Atlantic Forest remains scarce and might not prevent connectivity between species’ remnant patches. We thus evaluated the potential connectivity of projected Araucaria distribution in the present and future under climate change and current land-use, using a species distribution model with graph theory. Araucaria’s current connectivity—through the Mixed and Dense Forests—ranges entirely through the landscape, with 715 connecting arcs (212 within protected areas). However, only 7% of its current distribution is encompassed by protected areas. Under future climate change in 2085, connectivity is expected to decrease by 77% compared with current projections. In the future, Araucaria subpopulations will be concentrated at higher elevations in unprotected suitable areas. We suggest that specific regions in southern and southeastern Brazil might be targeted as priority conservation areas jointly to major existing protected areas. These areas will sustain Araucaria connectivity and protection. As a keystone species, by safeguarding Araucaria we protect the socioecological system in southern and southeast Brazil and potentially promote forest expansion.
... Human activities such as illegal logging, agricultural pressure, illegal fires and habitat fragmentation compromise the survival and recruitment of endemic trees (Seddon et al. 2000;Mittermeier et al. 2005), sometimes reducing their distribution to small areas with just a few individuals (Kremen et al. 2008). Although Madagascar's government has carried out significant efforts to increase the number of protected areas (Gardner et al. 2018), the data available to inform tree restoration and conservation decisions remains limited, many taxa remain unprotected (Kremen et al. 2008), especially many of Madagascar's endemic tree species (Callmander et al. 2007;Vieilledent et al. 2013;Rakotoarinivo et al. 2014) which are rarely included in management planning. To preserve the island's 1 3 charismatic flora and fauna, further conservation and restoration actions must be implemented urgently (Rakotoarinivo et al. 2014). ...
... see S3) with a 30 arc-second resolution grid (i.e. 1 km 2 resolution), these were used as predictors in our distribution models. Without a general scientific consensus about the best method to determine relevant predictors for target species ), we performed a Principal Component Analysis (PCA) (Legendre and Legendre 1998) using SPSS statistical software to determine the influence of the non-correlated bioclimatic variables (Vieilledent et al. 2013). ...
... Previous studies (Anderson and Martinez-Meyer 2004) demonstrated that modern land-cover classifications should not be used for museum herbarium datasets, and that soil-type and elevation data generalize better when they are correlated with bioclimatic variables (Phillips et al. 2009). Based to these findings we included altitude, slope, and geology as continuous and categorical environmental variables in our model (Du Puy and Moat 1996;Vieilledent et al. 2013). Franklin (2010) defines a Species Distribution Model as a model that relates species distribution data with information on the environmental and spatial characteristics of those locations (Elith et al. 2011;Qin et al. 2017). ...
Madagascar is one of the most biodiverse countries in Africa, due to its level of endemism and species diversity. However, the pressure of human activities threatens the last patches of natural vegetation in the country and conservation decisions are undertaken with limited data availability. In this study, we use free online datasets to generate distribution models of 1539 endemic trees and prioritise for conservation and restoration considering threat, alongside conservation value and cost. Threats considered include illegal logging, forest degradation and agriculture or slash and burns activities. We found that the areas with the highest potential concentration of species are along the north and south-east of the country where more than 400 tree species can be found. Most scenarios identify a common conservation and restoration priority area along the north east of the country. Our findings guide managers, conservation organizations or governments in decisions about where to invest their limited conservation resources.
... Species distribution models (SDM) are useful tools in conservation planning and management to project the effects that climate change could have on an endangered species' distribution [7,14,15]. As our global awareness on climate change increases, SDM have progressively been used to project the effect of climate change on the distribution of invasive pests, pathogens, and endangered species [14,[16][17][18][19][20][21][22]. Increasingly, studies have also started assessing the effectiveness of protected areas at conserving endangered species at present and in the future by incorporating climate change SDM [18-23]. ...
... Increasingly, studies have also started assessing the effectiveness of protected areas at conserving endangered species at present and in the future by incorporating climate change SDM [18-23]. One study conducted by Vieilledent et al. (2013) explored the effects of climate change on three endangered species of Madagascar (Adansonia grandidieri Baill, Adansonia perrieri Capuron and Adansonia suarezensis H. Perrier) and how climate change would modify the effectiveness of protected areas in the future. It was found that in the future, as a result of climate change, no protected areas were viable for conserving two of these species, which puts them at risk of future extinction [19]. ...
... One study conducted by Vieilledent et al. (2013) explored the effects of climate change on three endangered species of Madagascar (Adansonia grandidieri Baill, Adansonia perrieri Capuron and Adansonia suarezensis H. Perrier) and how climate change would modify the effectiveness of protected areas in the future. It was found that in the future, as a result of climate change, no protected areas were viable for conserving two of these species, which puts them at risk of future extinction [19]. ...
Walker’s Manihot, Manihot walkerae, is an endangered plant that is endemic to the Tamaulipan thornscrub ecoregion of extreme southern Texas and northeastern Mexico. M. walkerae populations are highly fragmented and are found on both protected public lands and private property. Habitat loss and competition by invasive species are the most detrimental threats for M. walkerae; however, the effect of climate change on M. walkerae’s geographic distribution remains unexplored and could result in further range restrictions. Our objectives are to evaluate the potential effects of climate change on the distribution of M. walkerae and assess the usefulness of natural protected areas in future conservation. We predict current and future geographic distribution for M. walkerae (years 2050 and 2070) using three different general circulation models (CM3, CMIP5, and HADGEM)
and two climate change scenarios (RCP 4.5 and 8.5). A total of nineteen spatially rarefied occurrences
for M. walkerae and ten non-highly correlated bioclimatic variables were inputted to the maximum
entropy algorithm (MaxEnt) to produce twenty replicates per scenario. The area under the curve (AUC) value for the consensus model was higher than 0.90 and the partial ROC value was higher than 1.80, indicating a high predictive ability. The potential reduction in geographic distribution for M. walkerae by the effect of climate change was variable throughout the models, but collectively they
predict a restriction in distribution. The most severe reductions were 9% for the year 2050 with the CM3 model at an 8.5 RCP, and 14% for the year 2070 with the CMIP5 model at the 4.5 RCP. The future
geographic distribution of M. walkerae was overlapped with protected lands in the U.S. and Mexico in order to identify areas that could be suitable for future conservation efforts. In the U.S. there are several protected areas that are potentially suitable for M. walkerae, whereas in Mexico no protected areas exist within M. walkerae suitable habitat.
... & H. Perrier, A. za Baill (Bell et al., 2015;Cron et al., 2016;Douie et al., 2015;Jarnevich et al., 2015;Pettigrew et al., 2012). These endemic baobabs are currently distributed in western Madagascar, some within a narrow range while others are widely distributed along the western part of the island (Pettigrew et al., 2012;Vieilledent et al., 2013). Three of the six species (A. ...
... Few studies have examined baobab conservation (Lisao et al., 2018). Vieilledent et al. (2013) described the current distribution of three endangered baobab species in Madagascar (A. suarezensis, A. perrieri, A. grandidieri), and predicted the impact of climate change on suitable habitat in the future. However, information is lacking on suitable habitat for the three widespread baobab species (A. ...
Madagascar, a globally renowned biodiversity hotspot characterized by high rates of endemism, is one of the few remaining refugia for many plants and animal species. However, global climate change has greatly affected the natural ecosystem and endemic species living in Madagascar, and will likely continue to influence species distribution in the future. Madagascar is home to six endemic baobab (Adansonia spp., Bombacoideae [Malvaceae]) species (A. grandidieri, A. suarezensis, A. madagascariensis, A. perrieri, A. rubrostipa, A. za), which are remarkable and endangered plants. This study aimed to model the current distribution of suitable habitat for each baobab species endemic to Madagascar and determine the effect that climate change will have on suitable baobab habitat by the years 2050 and 2070. The distribution was modeled using MaxEnt based on locality information of 245 occurrence sites of six species from both online database and our own field work. A total of seven climatic variables were used for the modeling process. The present distribution of all six Madagascar’s baobabs was largely influenced by temperature-related factors. Although both expansion and contraction of suitable habitat are predicted for all species, loss of original suitable habitat is predicted to be extensive. For the most widespread Madagascar baobab, A. za, more than 40% of its original habitat is predicted to be lost because of climate change. Based on these findings, we recommend that areas predicted to contract in response to climate change should be designated key protection regions for baobab conservation.
... (Za baobab) and Adansonia grandidieri Baill. (Grandidier's baobab or Reniala), which grow in west and south of the island [2,10,11]. Our research also intends to identify the oldest baobab of Madagascar. ...
... However, recent investigations based on photo-interpretation of very high resolution satellite images, also validated by field investigations, demonstrate that the population of A. grandidieri is much larger than previous estimates. According to this new research, the total population of A. grandidieri, which covers an area of over 25,000 km 2 along the Mangoky river and in the west part of the Menabe region, is around 1.2-1.3 million mature individuals [10]. ...
The article reports the AMS radiocarbon investigation of the two largest known Adansonia grandidieri specimens. The two baobabs, which are named Tsitakakoike and Pregnant baobab, are located in Southwestern Madagascar, near Andombiro. A third specimen from this area, the House baobab, was also investigated. According to measurements, Tsitakakoike is the biggest individual above ground level of all Adansonia species. The House baobab was selected for its exposed structure, which is identical to the closed ring-shaped structure with false cavities identified by us in large and old Adansonia digitata specimens. According to our research, Tsitakakoike and the Pregnant baobab have multi-stemmed cylindrical trunks which are mainly hollow; the two very large baobabs also possess a ring-shaped structure. The radiocarbon dates of the oldest wood samples collected from the large trunks were 1274 ± 20 bp for Tsitakakoike and 930 ± 20 bp for the Pregnant baobab. According to their original positions and to the architectures of the two A. grandidieri, the ages of Tsitakakoike and Pregnant baobab would be between 1300 and 1500 years. Therefore, A. grandidieri becomes the third Adansonia species with individuals that can live over 1000 years, according to accurate dating results.
... Thus, over these suitable areas, we calculated the area within the Atlantic Forest (in km 2 ) with complete climatic/environmental information available. Within these areas, we also randomly sampled 1000 points to collect data to describe the species' realized climatic niche (see Tagliari et al., in review;Vieilledent et al., 2013). To predict species future distribution we followed the ensemble forecasting approach under committee averaging (Araújo and New, 2007) by combining our four previously selected algorithms with the tree Global Circulation Models mentioned above. ...
... On one hand, under the LD scenario, species future distribution cannot surpass the area calculated for the current baseline. On the other hand, in the NLD scenario, we consider the species' capacity to expand their climatic niche beyond their predicted occurrence area in the present (Tagliari et al., in review;Vieilledent et al., 2013). ...
Biodiversity across the Neotropics is a result of selective forces along a myriad of ecosystems. The Brazilian Atlantic Forest biome embodies 321 mammal species; only a small parcel of the species is considered piscivore. The Atlantic Forest biota is threatened by multiple factors, from habitat loss to climate changes. We aimed to understand the current distribution of the six extant piscivore mammals and the distribution of this trophic guild, predicting their distribution under climate change across the Atlantic Forest and identifying areas for the trophic guild conservation prioritizations. We used data on species occurrence based on the GBIF database and literature, and climatic data from WorldClim. We perform Species Distribution Modelling (SDM) to derive the piscivores distribution and the presence of this trophic guild. Our results reveal that piscivores distribution is already restricted in the present (average 8.84%), even the presence of this trophic guild (6.42%). Trophic guild distribution in the short-term under climate change may represent less than 6.5% across the Atlantic Forest, will be contracting by −30.0%. We conclude that combinations of factors inductors of biodiversity loss will be empowered by climate changes, leading to more restricted species distribution. SDM is fundamental to understand the species distribution to prioritize conservation efforts from local to pan-continental scales, being paramount to slow down the consequences of climate change.
... (Za baobab) and Adansonia grandidieri Baill. (Grandidier's baobab or Reniala), which grow in west and south of the island [2,10,11]. Our research also intends to identify the oldest baobab of Madagascar. ...
... However, recent investigations based on photo-interpretation of very high resolution satellite images, also validated by field investigations, demonstrate that the population of A. grandidieri is much larger than previous estimates. According to this new research, the total population of A. grandidieri, which covers an area of over 25,000 km 2 along the Mangoky river and in the west part of the Menabe region, is around 1.2–1.3 million mature individuals [10]. The height, girth and shape of mature and old specimens may be very different and usually depend on their locations. ...
... This mega-tree species is still a dominant element of the emergent layer across forests from Amazonia to southern Mexico. Baobab trees (Adansonia spp.) are sacred entities and a cosmovision element for several African cultures (Vieilledent et al., 2013), as well as magnificent sightseeing targets for ecotourism. In India, strangler figs (Ficus religiosa, F. benghalensis), which begin life as epiphytes but achieve the stature of mega-trees (Kandari et al., 2014) are also of cultural significance. ...
... In addition to their significance to local communities, several sacred trees, groves and forests have been spared from agricultural conversion, thereby becoming important conservation sites (Bhagwat and Rutte, 2006). Sacred mega-trees also increasingly attract tourism and pilgrimages, rendering this a key topic in both conservation and sustainable development science (Haberman, 2013;Vieilledent et al., 2013). ...
Very large tropical forest trees (‘mega-trees’) represent an irreplaceable habitat associated with large benefits in terms of biodiversity and ecosystem services. Here we provide a comprehensive overview of the importance of tropical mega-trees relative to biodiversity persistence, ecosystem services, and sociocultural value. We describe all contemporary threats to mega-trees as a result of the conversion of old-growth forests into human-degraded landscapes exposed to climate change. We reveal a myriad of taxa, functional groups and ecosystem services that are directly or indirectly supported by tropical mega-trees, such as highly illuminated crowns for epiphytes and large boles and branches sheltering many vertebrate and invertebrate taxa. Mega-trees also amplify the resource spectra associated with non-redundant niche space, including thermal buffering and extended vertical microclimates above the forest canopy. Mega-trees also make the largest contribution to forest productivity, aboveground biomass, and timber. However, protecting this resource is a major challenge due to the natural rarity of mega-trees, illegal logging, old-growth forest conversion and climate change. We argue for ‘productive forest landscapes’ as a strategy to protect mega-trees and highlight their connections with sustainable development goals and other global targets. This strategy poses economic, political, technological and social challenges, as sparing tropical forests still incurs high opportunity costs that few stakeholders can realistically afford. Despite these challenges, the future of tropical forests mega-trees and local livelihoods are inextricably linked, and productive forest landscapes would bring clear unanticipated benefits for future generations and tropical biodiversity.
... In contrast to process-based approaches, simpler correlative methods could offer rapid and robust alternatives for the projection of the effects of climate change on tropical forest carbon storage. Despite known limitations (including the fact that they usually do not take into account biotic interactions, species adaptation and dispersal ability, see Pearson & Dawson (2003)), bioclimatic envelope models have been widely used to project the effect of climate change on biodiversity at both the species (Guisan & Zimmermann, 2000;Thuiller et al., 2005;Vieilledent et al., 2013a) and biome level (Hannah et al., 2008;Zelazowski et al., 2011). For instance, Zelazowski et al. (2011) predicted a forest retreat in Amazonia, Central America and parts of Africa, and expansion in other regions, in particular around the Congo Basin. ...
... Although it is common to predict future species range using bioclimatic envelope models and climatic projections (Guisan & Zimmermann, 2000;Pearson & Dawson, 2003;Thuiller et al., 2005;Vieilledent et al., 2013a), it is difficult to predict changes in tree species composition and forest structure (tree height and diameter distribution), and thus forest carbon stocks, following climate change. Nonetheless, it is still possible to directly correlate forest biomass to climate. ...
Recent studies have underlined the importance of climatic variables in determining tree height and biomass in tropical forests. Nonetheless, the effects of climate on tropical forest carbon stocks remain uncertain. In particular, the application of process-based dynamic global vegetation models have led to contrasting conclusions regarding the potential impact of climate change on tropical forest carbon storage. 2.Using a correlative approach based on a bioclimatic envelope model and data from 1771 forest plots inventoried during the period 1996-2013 in Madagascar over a large climatic gradient, we show that temperature seasonality, annual precipitation and mean annual temperature are key variables in determining forest above-ground carbon density. 3.Taking into account the explicative climate variables, we obtained an accurate (R2 = 70% and RMSE = 40 Mg.ha−1) forest carbon map for Madagascar at 250 m resolution for the year 2010. This national map was more accurate than previously published global carbon maps (R2 ≤ 26% and RMSE ≥ 63 Mg.ha−1). 4.Combining our model with the climatic projections for Madagascar from 7 IPCC CMIP5 global climate models following the RCP 8.5, we forecast an average forest carbon stock loss of 17% (range: 7-24%) by the year 2080. For comparison, a spatially homogeneous deforestation of 0.5% per year on the same period would lead to a loss of 30% of the forest carbon stock. 5.Synthesis: Our study shows that climate change is likely to induce a decrease in tropical forest carbon stocks. This loss could be due to a decrease in the average tree size and to shifts in tree species distribution, with the selection of small-statured species. In Madagascar, climate-induced carbon emissions might be, at least, of the same order of magnitude as emissions associated to anthropogenic deforestation. This article is protected by copyright. All rights reserved.
... Due to its very restricted distribution, exploitation for wood and charcoal, eating of seeds by introduced rats, and fire, A. perrieri was considered the most endangered of all Malagasy baobabs. (Ravaomanalina & Razafimanahaka, 2016) although a recent population estimate is in excess of one million individuals (Vieilledent et al., 2013). Adansonia za Baill. ...
... Ecological extinction (unable to regenerate in situ) if not physical extinction is possible because of the low regeneration potential (Baum, 1995). In addition to direct and immediate threats the species are vulnerable to long term climate change (Vieilledent et al., 2013). This study shows that A. suarezensis in particular is vulnerable to climate change and more than half the population in the future (the years 2050 to 2080) will be in areas unsuitable for the species. ...
Baobabs list eight species of the genus Adansonia L. (Bombacaceae Malvaceae). One species is endemic to mainland Africa, one to Australia and six to Madagascar. Three Malagasy species are classed by IUCN as Lower Risk/Near Threatened and three are Endangered with limited numbers under the criteria of Extent of Occurrence and Area of Occupancy. The Antsiranana (Diego Suarez) region in northern Madagascar is home to A. madagascariensis Baill., A. suarezensis H. Perrier and A. perrieri Capuron. These are threatened by multiple causes. Naturally low regeneration rates, deforestation, use of fuelwood and charcoal, commercial logging, livestock grazing, collection and consumption of fruit, seed collection for use in cosmetics manufacture, and illegal fires are among these threats. Ecological (unable to regenerate in situ) if not physical extinction is possible because of the low regeneration potential. In addition to direct and immediate threats, the species are vulnerable to long term climate change. Small and fragmented populations, human-wildlife conflict, climate change, invasive species, diseases, lack of conservation law enforcement and inadequate knowledge and research make the prognosis for the survival of this part of Madagascar's heritage and biodiversity not very positive.
... We created the climate change threat maps assuming that all selected species react in the same way to climatic conditions becoming less suitable. Also differences in plasticity of functional traits [59], in genetic variability [60], in seed dispersal [61], etc., can play an important role in vulnerability of species to a rapidly changing environment. Due to the existing complexity of the multi-threat approach, we decided not to consider this additional aspect in our analysis. ...
Over the last decades agroforestry parklands in Burkina Faso have come under increasing demographic as well as climatic pressures, which are threatening indigenous tree species that contribute substantially to income generation and nutrition in rural households. Analyzing the threats as well as the species vulnerability to them is fundamental for priority setting in conservation planning.
... Some researchers, use model to give substantial evidence for climate warming that will bring positive ecological effects, or make vegetation belt move along with the climate change. Vieilledent et al. (2013) estimated the vulnerability of three endangered baobab species with climate change tending to extend the suitable habitat of the species. Others found that climate change will be infaust to the growth and development of plants. ...
The root of riparian Homonoia (RRH), a medical plant with high economic value, is mainly distributed at riparian area in Southeast Asia. Its population has declined significantly, and the species has become endangered in recent decades. Understanding the habitat requirement, evaluating the habitat quality, and predicting its potential habitat are significant for protecting this species. Here, 223 occurrence records of the RRH were collected globally. The key eco-factors influencing species distribution were selected based on correlation analysis and principal component analysis. Habitat suitability simulation found on four climate-warming scenarios (RCP 2.6, RCP4.5, RCP6.0 and RCP8.5), given by IPCC. The results found that both the suitable area and the suitability of the RRH habitat increase as the climate warming. The increasing range achieved a maximum at RCP4.5.
... Some studies bypass consideration of dispersal constraints by comparing the spatial overlap of current ranges with either projected future ranges or protected areas as an assessment of connectivity (e.g., Ordonez & Williams 2013;Vieilledent et al. 2013). Others incorporate more biological realism by comparing climate velocities with biotic velocities (e.g., Carroll et al. 2015) or with empirically derived species' dispersal rates (e.g., Schloss et al. 2012). ...
Increasing connectivity is an important strategy for facilitating species range shifts and maintaining biodiversity in the face of climate change. To date, however, few studies have included future climate projections in efforts to prioritize areas for increasing connectivity. Here, we identify key areas likely to facilitate climate-induced species movement across western North America. Using historical climate datasets and future climate projections, we mapped potential routes between current climates and their future analogs with a novel moving-window analysis based on electrical circuit theory. In addition to tracing shifting climates, the approach accounts for landscape permeability and empirically-derived species dispersal capabilities. We compared connectivity maps generated with our climate-change informed approach to maps of connectivity based solely on the degree of human modification of the landscape. We show that including future climate projections in connectivity models substantially shifts and constrains priority areas for movement to a smaller proportion of the landscape than when climate projections are not considered. Potential movement, measured as current flow, decreases in all ecoregions when climate projections are included, particularly when dispersal is limited, making climate analogs inaccessible. In addition, many areas emerge as important for connectivity only when climate change is modeled in two time steps rather than in a single time step. Our results illustrate that movement routes needed to track changing climatic conditions may differ from those that connect present-day landscapes. Incorporating future climate projections into connectivity modeling is an important step towards facilitating successful species movement and population persistence in a changing climate. This article is protected by copyright. All rights reserved.
... Résolution Spatiale (THRS) acquises par le satellite Quickbird (résolution 61 cm) et accessibles depuis l'application Google Earth. Les baobabs ont été identifiés sur la base des critères d'identification tels que la taille de la couronne, la forme, la hauteur de l'arbre et la forme de l'ombre projetée (Vieilledent et al., 2013). ...
Baobab trees are long-lived trees for which reproduction and biology have led various research questions. This thesis aims understanding the biological processes involved in seed dispersal of two species of Malagasy baobabs (A. rubrostipa and A. grandidieri) and the effect on population spatial pattern. Experiments were conducted to clarify the role of vertebrate dispersers on seed dissemination and seed germination. Analysis of the spatial distribution was discussed at the population level. The spatial referencing of adult baobabs has been achieved on the basis of a census and crown delimitation using imagery with very high spatial resolution. This work demonstrated the mutualistic relationships within ecosystems for seed dispersals and the baobab recruitment. In particular, our results showed that (i) the disappeared Malagasy megafauna as giant tortoises can provide dispersal of intact baobabs seeds, (ii) the large livestock can replace the role of the Malagasy megafauna ; pulp removal and dormancy breaking are facilitated by the passage of seeds in the digestive tract of these animals (iii) the big size of the fruits is compatible with the involvement of current frugivores such as lemurs and (iv) dispersal by floating seeds can prove to be an equally effective mechanism in the absence of main animals dispersers. This study also demonstrated that the capacity of seed dispersal and the access to the nearest water point due to arid conditions of their habitats are main determinants of spatial patterns of baobabs. These conditions can play the role of environmental filter selecting individuals that are far from water point.
... For example, the line transect method is often used in flat or homogenous habitat areas because it is difficult to obtain a sufficient number of samples in mountains or forests. In recent years, with the progress of ''3S'' technologies— remote sensing, geographical information system (GIS), and global positioning system (GPS)—models have been developed to predict and evaluate the potential distribution areas of target species (Araujo et al., 2011; Brown, 2014; Chitale, Behera & Roy, 2014; Elith & Leathwick, 2009; Fourcade et al., 2013; Vieilledent et al., 2013; Ward & Morgan, 2014). These quantitative models (e.g., species distribution models, SDMs) are valuable tools to assess habitat suitability for species at landscape scales. ...
Background. Understanding species distribution, especially areas of overlapping habitat between sympatric species, is essential for informing conservation through natural habitat protection. New protection strategies should simultaneously consider conservation efforts for multiple species that exist within the same landscape, which requires studies that include habitat overlap analysis.
Methods. We estimated the potential habitat of cervids, which are typical ungulates in northern China, using the present locations of red deer (Cervus elaphus; N = 90) and roe deer (Capreolus capreolus; N = 106) in a Maximum Entropy (MaxEnt) model. Our study area was a human-dominated landscape in the Tieli Forestry Bureau located at the southern slope of the Lesser Xing’an Mountains. We grouped 17 environmental predictor variables into five predictor classes (terrain, habitat accessibility, land cover, vegetation feature, and interference), which were used to build habitat suitability models.
Results. Habitat accessibility and human interferences were found to have the strongest influence on habitat suitability among the five variable classes. Among the environmental factors, distance to farmland (26.8%), distance to bush-grass land (14.6%), elevation (13.5%), and distance to water source (12.2%) were most important for red deer, distance to farmland (22.9%), distance to settlement (21.4%), elevation (11.6%), and coverage of shrub-grass (8%) were most important for roe deer. Model accuracy was high for both species (mean area under the curve (AUC) = 0.936 for red deer and 0.924 for roe deer). The overlapping habitat comprised 89.93 km² within the study area, which occupied 94% of potentially suitable habitat for red deer and 27% for roe deer.
Conclusions. In terms of habitat suitability, roe deer showed greater selectivity than red deer. The overlapping habitat was mostly located in the eastern mountains. The southwestern plain was not a suitable habitat for deer because it was close to Tieli City. Regarding management measures, we suggest that priority protection should be given to the potential areas of overlapping deer habitats found in this study.
... madagascariensis, A. rubrostipa et A. za). Il est à noter également que parmi ces espèces de baobabs, certaines pourraient être particulièrement vulnérables au changement climatique (Vieilledent et al. 2013). Enfin, les baobabs de Madagascar ont à la fois des valeurs pratiques, culturelles et spirituelles pour les communautés villageoises (Wickens et Lowe 2008, Marie et al. 2009). ...
With lemurs, baobabs are the most emblematic species of Madagascar internationally. Seven species of the nine existing in the world are Madagascan endemic. This fact testifies the high rate of the biodiversity of the island. Having signed a number of international conventions, Madagascar intends to underline its commitment to the management and conservation of its natural resources. The international system of conservation framing is used for the implementation of national strategy. Thus, in addition to the international system of conservation systems such as the CBD, IUCN or CITES, baobabs of Madagascar are considered as non - timber forest products according to Decree N. 2915/87 of 7 September 1987 related to products accessories forest even if no term is clearly stipulated in this text. Moreover, there is no regulatory framework or specific text about conservation or exploitation of baobabs in Madagascar. Protected areas are then the only protection structures for baobabs. All species of Malagasy baobabs are represented in protected areas but their representation differs depending on the distribution of each species. Except for two protected areas, the baobab is not yet among the specific targets of conservation of protected areas in Madagascar. Adansonia grandidieri is an exception. It benefits indeed from two regional frameworks that specify measures to protect the species and priority activities to be undertaken for the species with the Dinan'ny Menabe and the regional conservation strategy for the species validated in 2013. At the local level, tools and instruments governing the management transfer could constitute framing elements for the management of baobabs. Some species have in fact non-negligible economic values without forgetting the cultural and religious values of some baobab trees. The implementation of the strategy for the conservation of each species is necessary at all levels especially in protected areas as three species are classified as ‘Endangered’ by IUCN. The conservation is necessary to ensure both sustainability of the species and integrity of all uses of baobabs.
... In Madagascar or in any other African countries, conservation is primarily focused on rare and endangered species and is used to draw the attention of national and international communities on the issue of conservation sites [10]- [12] while expressions of interest on the valorization of geological interest in socio-economic and tourism related sectors are limited or non-existent, which limits the scope of implementation efforts [5], [13] and [14]. Accordingly, the aim of this paper is to establish a prototype sheets for inventory of geoheritage appropriately adapted not only for Madagascar but also for other developing countries. ...
Geological heritage inventory procedures and templates have been principally emerged from European countries. Each of these countries has developed its proper method of inventory based on its natural heritage, recognized on local and/or regional scales. Natural sites were mainly identified and characterized in a particular geological context, which is usually very unique, valuable and impressive; resulting in the protection of the sites. Madagascar is known internationally as a beautifully landscaped island, but the impressive sites were not cataloged. We carried out a series of field inventory of potential geological sites within the Isalo National Park in southern Madagascar. We invented several inventory sheets in order to record the most detailed information about the sites identified within the park. This is to aid in organizing the park and to establish a sustainable base for the creation of a geopark, and also they help us to build a database for geosites and their classifications. This article suggests a prototype model for inventorying intangible geosites, paleosites and geomorphosites. Our inventory sheets help to identify and to promote geological importance of any sites, not only for academia but also for other sectors such as tourism and conservation.
... Rates of deforestation in this region are extremely high and are accelerating due to human population growth accompanied by slash-and-burn agriculture, logging, and other forms of overexploitation of natural resources (Harper et al. 2007, Malik 2013, Vieilledent et al. 2013a). Different strategies have been used for conserving the remaining forests in these islands, including use of distributions of taxa to characterize areas of endemism with high conservation value (Kremen et al. 2008, Hawlitschek et al. 2011, Vieilledent et al. 2013b and to integrate the local people into conservation strategies (Hackel 1999, Birkinshaw et al. 2013. ...
Antherina suraka (Boisduval, 1833) (Lepidoptera: Saturniidae) is endemic to Madagascar and the Comoros. Investigations in the 1950s and 1960s found slight morphological differences between typical populations and those from dry areas of Madagascar, a “form”—australis—that was not given formal taxonomic recognition. In the Comoros, A. suraka is represented by a distinct subspecies, A. suraka comorana Viette 1965. The goal of this study was to increase insight into the biological significance of intraspecific variation within A. suraka by studying male genitalia and flight times, and DNA barcode sequences. We also tested whether genetic divergence between sites was correlated with geographic distances or host use. No differences in male genitalia were found. Moths from western Madagascar were found typically flying 2 h earlier in the evening than eastern moths. A Bayesian phylogeny derived from the mtDNA barcode sequences supported: 1) a western clade comprising the “australis” populations, 2) a clade composed mainly of specimens from eastern/central Madagascar, and 3) a third unit in the Comoros representing the subspecies comorana. While these results could be viewed as supporting the existence of more than one species within A. suraka, recovery of eastern haplotypes in western areas, and the presence of genetic isolation by distance, weaken the case for taxonomic division: more genetic data are needed. Regardless of exactly how the systematic status of this species is resolved, the presence of three distinct populations of A. suraka living in different habitats illustrates the importance of protecting forests in this biodiversity hotspot.
... Using sensitivity, exposure, and adaptive capacity, vulnerability assessments can identify 1) which species are most vulnerable, 2) why those species are vulnerable, and 3) which factors can potentially be leveraged to reduce vulnerability (Williams et al. 2008, Foden et al. 2013. Several recent studies have assessed vulnerability to climate-change for trees species (e.g., Coops and Waring 2011, Devine et al. 2012, Booth 2013, Vieilledent et al. 2013. However, these studies have focused largely only the most common and economically important species and most have assessed one or two components of vulnerability, but not all three-sensitivity, exposure, and adaptive capacity. ...
Many recent changes in tree species distributions, mortality, and growth rates have been linked to changes in climate. Managing forests in the face of climate change will require a basic understanding of which tree species will be most vulnerable to climate change and in what ways they will be vulnerable. We assessed the relative vulnerability to climate change of 11 tree species in western North America using a multivariate approach to quantify elements of sensitivity to climate change, exposure to climate change, and the capacity to adapt to climate change. Our assessment was based on a combination of expert knowledge, published studies, and projected changes in climate. Of the 11 species, Garry oak (Quercus garryana) was determined to be the most vulnerable, largely because of its relatively high sensitivity. Garry oak occupies some of the driest low woodland and savanna sites from British Columbia to California and is highly dependent on disturbances, such as periodic, low intensity fire. Big leaf maple (Acer macrophyllum) was determined to be the least vulnerable, largely because of its adaptive capacity. Big leaf maple can reproduce quickly after disturbances and its seeds can disperse long distances potentially allowing it to move in response to a changing climate. Our analyses provide a framework for assessing vulnerability and for determining why some species will likely be more vulnerable than others. Such information will be critical as natural resource managers and conservation practitioners strive to address the impacts of climate change with limited funds.
... For Kenya, on the other hand, NRC (2008) estimates that less than 10 % of the potential inherent in its existing baobabs are utilized, but this statement needs verification, particularly if commercial use is to be promoted for improving livelihoods of local communities. Aerial tree identification and mapping of baobab populations, as already suggested by Wickens (1966), in combination with ground referencing as conducted by Vieilledent et al. (2013) on Malagasy baobab species may help to assess the sizes and distributions of baobab populations in Sudan and Kenya. ...
Wild edible fruits hold great potential for improving human diets, especially in agricultural societies of the developing world. In Africa, a well-known supplier of such fruits is the baobab (Adansonia digitata L., Malvaceae), one of the most remarkable trees of the world. Several studies in different African countries have highlighted this indigenous fruit tree as a priority species for domestication and expanded use. However, internationally available information on baobab in East Africa, particularly in Sudan and Kenya, remains scarce. This review aims to shed light on the ecology, diversity and current level of utilization of baobab in East Africa in order to facilitate domestication and conservation of the species. A list of priority research areas is provided at the end of the review to encourage further studies and investment in this unique plant taxon.
... However, in (2008) estimates that less than 10 % of the potential inherent in its existing baobabs are utilized, but this statement needs verification, particularly if commercial use is to be promoted for improving livelihoods of local communities. Aerial tree identification and mapping of baobab populations, as already suggested by Wickens (1966), in combination with ground referencing as conducted by Vieilledent et al. (2013) on Malagasy baobab species may help to assess the sizes and distributions of baobab populations in Sudan and Kenya. ...
The objective of this paper is to give an overview on the Gum Arabic Producers’ Associations in Sudan with special focus on their problems and challenges. The paper relied on reviewing literature from different secondary sources. The gum arabic associations established during phase III of the Restocking of Gum Belt Project (RGBP) in North Kordofan State in 1992 with a main objective of promoting financial returns from gum arabic production and marketing for the project participants. This was well connected with the consolidate idea of self-reliance among rural community members to work for the development of both Gum Belt and gum arabic production, besides the overall objective of rural development. However, there were many problems confronted the gum Arabic producers associations in Sudan such as funds, administrated issues, the relation between the members, fluctuation of the gum prices, macroeconomic trends and challenge of technological innovations for developing synthesized gum substitutes. Over and above, the global phenomena climate change has a remarkable effect on the reduction of the gum productivity due to rainfall fluctuation in terms of intensities and distribution, which has consequently resulted in shifting gum belt and gum production activities toward south. This is considered as a real challenge to community development in the northern part of the belt to find other ways to improve gum productivity and marketing. Being so it is also a good opportunity to introduce new soft technologies (e.g. associations, community development, etc...) in areas to the south where farmers have no experience with the gum production and the related activities.
... (za baobab) and Adansonia grandidieri Baill. (Grandidier's baobab or reniala), which grow in west and south; each of these species is represented by over 1 million individuals [2,11,12]. The research is based on our approach which consists of AMS (accelerator mass spectrometry) radiocarbon dating of small wood samples collected from different areas of the trunk/stems of large baobabs [6,8]. ...
... Species' abilities to shift their ranges will also be limited by the availability and distribution of suitable habitat (Chen et al., 2009;Feeley and Silman, 2010;Hodgson et al., 2009), and species that fail to shift their ranges may face increased likelihood of extinction (Thomas et al., 2004). The effectiveness of PAs to conserve tropical species under climate change has been questioned (Klorvuttimontara et al., 2011;Marini et al., 2009;Vieilledent et al., 2013), and if the connectivity of PAs is reduced due to land-use change, it may become difficult for species to track climate changes and move between PAs. In temperate regions, PAs have been shown to be effective in facilitating latitudinal range expansions (Thomas et al., 2012), but the effectiveness of PAs to conserve tropical biota responding to climate changes along elevation gradients has received little attention. ...
Protected areas (PAs) are key for conserving rainforest species, but many PAs are becoming increasingly isolated within agricultural landscapes, which may have detrimental consequences for the forest biota they contain. We examined the vulnerability of PA networks to climate change by examining connectivity of PAs along elevation gradients. We used the PA network on Borneo as a model system, and examined changes in the spatial distribution of climate conditions in future. A large proportion of PAs will not contain analogous climates in future (based on temperature projections for 2061–2080), potentially requiring organisms to move to cooler PAs at higher elevation, if they are to track climate changes. For the highest warming scenario (RCP8.5), few (11–12.5%; 27–30/240) PAs were sufficiently topographically diverse for analogous climate conditions (present-day equivalent or cooler) to remain in situ. For the remaining 87.5–89% (210–213/240) of PAs, which were often situated at low elevation, analogous climate will only be available in higher elevation PAs. However, over half (60–82%) of all PAs on Borneo are too isolated for poor dispersers (<1 km per generation) to reach cooler PAs, because there is a lack of connecting forest habitat. Even under the lowest warming scenario (RCP2.6), analogous climate conditions will disappear from 61% (146/240) of PAs, and a large proportion of these are too isolated for poor dispersers to reach cooler PAs. Our results suggest that low elevation PAs are particularly vulnerable to climate change, and management to improve linkage of PAs along elevation gradients should be a conservation priority.
... A common application of SDMs is to predict the impact of climate change on the potential range size and survivorships of focal species [58,59]. With this potential application in mind, we further evaluated the effect of using unverified data versus verified data in generating SDM range predictions. ...
Species distribution models (SDMs) are popular tools for predicting the geographic ranges of species. It is common practice to use georeferenced records obtained from online databases to generate these models. Using three species of Phaedranassa (Amaryllidaceae) from the Northern Andes, we compare the geographic ranges as predicted by SDMs based on online records (after standard data cleaning) with SDMs of these records confirmed through extensive field searches. We also review the identification of herbarium collections. The species’ ranges generated with corroborated field records did not agree with the species’ ranges based on the online data. Specifically, geographic ranges based on online data were significantly inflated and had significantly different and wider elevational extents compared to the ranges based on verified field records. Our results suggest that to generate accurate predictions of species’ ranges, occurrence records need to be carefully evaluated with (1) appropriate filters (e.g., altitude range, ecosystem); (2) taxonomic monographs and/or specialist corroboration; and (3) validation through field searches. This study points out the implications of generating SDMs produced with unverified online records to guide species-specific conservation strategies since inaccurate range predictions can have important consequences when estimating species’ extinction risks.
... In order to study the past distribution of organisms, researchers used three approaches: fossil records analysis, molecular studies (phylogeography), and distribution modeling. 8,9 Nowadays, species distribution models have found many applications in ecology, [10][11][12][13] conservation, [14][15][16][17] and even paleoecology. 9,18 These models are based on niche theory 19 and are used to model the distribution of species through time and space. ...
Species distribution models have many applications in ecology, conservation, biogeography, and even paleoecology. In this study, we modeled the distribution of the Eastern Rock Nuthatch ( Sitta tephronota), a common rock dweller bird in Iranian Plateau, and determined most important climatic variables affecting the distribution of the species. We then projected the species distribution model into the past, Last Glacial Maximum (21,000 yr BP) and Last Interglacial (~120,000–140,000 yr BP), to investigate how the species’ range would have changed through time. Results indicated that Zagros Mountains and Alborz Mountains Kopet Dagh in the northeast of Iran are the most suitable habitats for the Eastern Rock Nuthatch. Annual mean temperature and annual precipitation identified as the most important variables in predicting the distribution of this species. During Last Glacial Maximum, potential distribution of Eastern Rock Nuthatch was larger from its current distribution; however, the species’ climatic niche remains relatively stable since Last Glacial Maximum. Our results also showed that during the Last Interglacial distribution, Eastern Rock Nuthatch was restricted to high elevations and was very different compared to its current distribution.
... In recent years, there have been many studies on the impact of climate change on the distribution of shrub and tree species in the world (Vieilledent et al. 2013;Gelviz-Gelvez et al. 2015;Koralewski et al. 2015;Remya et al. 2015;Chala et al. 2016;Wang et al. 2016;Shirk et al. 2018;Yun et al. 2018). Nevertheless, there are a few studies on the climate change impact on the geographic distribution of plant species in Iran (Fatemi Azarkhavarani et al. 2017;Haidarian Aghakhani et al. 2017;Taleshi et al. 2018), which show the currently suitable habitats which might decrease or disappear under different scenarios in 2050 and 2070. ...
The Hyrcanian climate in the northern parts of Iran has warmed over the past 50 years, but the impacts on plant species are unknown. As the longest-lived tree in the Hyrcanian forest, English yew, Taxus baccata L., is a rare and endangered species in the forests along the Iranian coasts of the Caspian Sea, which is likely affected by climate change. This paper explores the current and future distribution of this species, using four species distribution models. In order to project the effect of climate change on the distribution of English yew by 2050 and 2070, output from the HadGEM2-ES climate model was used for two RCPs scenarios (2.6 and 8.5). The results showed a good accuracy of all the models for the distribution of this species with a mean area under the receiver operating curve (AUC) of 0.92. Using ensemble forecasting as an algorithm for reducing the uncertainty in species distribution modeling shows that the suitable habitats for this species is about 6000 km² for the current climate conditions in the study area. Range size analysis indicates that in 2050, in the most optimistic scenario (RCP 2.6), only 17% of the habitats will retain their suitability, while in the most pessimistic scenario (RCP 8.5), this amount will decrease to 2%. In 2070, in the most optimistic scenario, only 10% of the currently suitable habitats will retain their suitability, while in the RCP 8.5, no stable suitable habitats will be left. It is strongly recommended that the impacts of climate change on English yew should be considered in the management decisions and conservation plans in the Hyrcanian forests.
... Alors que le couvert forestier (principalement des arbres fruitiers et des non indigènes) augmente dans des poches des hauts plateaux centraux (McConnell et al. 2015), une transition forestière (où les tendances de l'utilisation des terres passent d'une période de perte nette à une période de gain net) n'est pas attendue de sitôt à l'échelle nationale (Kull et al. 2007;Jones et al. 2018). Dans le même temps, le changement climatique modifie la répartition de certaines espèces forestières (Vieilledent et al. 2013) et rendra la vie encore plus difficile et plus précaire pour de nombreuses populations rurales (Harvey et al. 2014). Dans cette section, nous mettons en évidence certains des domaines les plus importants dans lesquels des progrès sont nécessaires si l'on veut inverser les tendances actuelles en matière de perte de forêts et de biodiversité. ...
... Ensemble forecasting is an appropriate solution to quantify the variation originating from a range of choices made during the modeling process (Araújo and New 2007). An ensemble forecasting which ultimately combines the predictions of different SDMs and GCMs can thus be used to quantify uncertainties associated with model projections under climate change (Vieilledent et al. 2013). ...
This study aimed to assess the impacts of climate change on the distribution of major tree species in the temperate forests of Northern Iran (also known as Hyrcanian forests). We analyzed the current distributions of the eleven major tree species using an ensemble approach involving five different species distribution models (generalized linear model, generalized additive model, generalized boosting model, classification tree analysis, and random forests) and generated the ensemble maps of the current and future distribution of each species. For the future, we used five general circulation models and two representative concentration pathways (RCPs). Finally, we mapped beta-diversity and changes in alpha-diversity of the tree species under climate change. Our analyses showed that generally, the climatically suitable habitats for most of the species tend to shift and shrink in the future. A shift in major trees boundaries will be expected both along an east-west gradient and along an altitudinal gradient under climate change scenarios. The results demonstrated that climate change is likely to exert a strong influence on beta-diversity and richness of the major tree species in northern forests of Iran. In total, beta-diversity of tree species will be higher in the central and eastern parts compared with the western areas under the climate change scenarios and the mid-elevations of the western Hyrcanian forests will likely experience the lowest beta-diversity through time, meaning that the impacts of climate change on these regions are minimal. The impacts of climate change on the distribution of major tree species in the Hyrcanian forests can be considered very severe and pose a high risk of loss in forest functions and services. Forest managers will encounter several uncertainties in the wood productions, plantation, restoration, and conservation plans due to climate change in the Hyrcanian forests.
... The approach provides valuable information on the viability of species 75 populations based on size-class distributions (SCDs), but is not appropriate to reliably predict 76 future population trends because SCD data are a static representation of the population at a 77 certain moment in time (Condit et al., 1998;Feeley et al., 2007). However, in the actual context 78 of increasing global warming producing rapid shifts in the distribution and abundance of species 79 ( Lenoir and Svenning, 2013;Vieilledent et al., 2013;You et al., 2018), estimates of the potential 80 effect of climate change on the future trajectories of species populations are urgently needed 81 to design current conservation and management measures that account for the anticipated 82 changes. In this regard, ecological niche modeling (ENM) has been widely used to project 83 current species distributions into future climate scenarios, thereby identifying climatic (e.g., 84 rainfall and air temperature) and non-climatic (e.g., topography, soil type) range-limiting factors 85 and predicting potential distributional patterns (i.e., range contraction or extension) under the 86 assumptions of niche conservatism (Blach-Overgaard et al., 2010;Elith et al., 2006;Noulèkoun 87 et al., 2017;Soberon and Peterson, 2005;You et al., 2018). ...
The increasing rate of land use intensification and the rising evidence of climate change impacts raise concerns about the viability of valued non-timber forest product (NTFP)-providing trees. This calls for the assessment of the current status and future trajectories of their populations. Using population data collected from three land-use types (e.g., grazing lands, riverine areas and natural forest) in western Tigray, we evaluated the vulnerability of the multipurpose baobab tree (Adansonia digitata L.) to human disturbances and climate change. The study was based on the premises that integrating ecological science with modeling tools and local knowledge would enhance the overall effectiveness of conservation strategies and community support. Therefore, based on field-based inventory, ecological niche modeling and a socioeconomic study, we characterized and mapped baobab current and future population distribution and documented local knowledge on the uses and management of the species. The characterization of the population structure showed that baobab stands were denser with larger-sized and taller trees in riverine areas and natural forest compared to grazing lands, suggesting adverse effects of human disturbances on its populations. Moreover, positively skewed size-class distributions with negative slopes in all land-use types indicated a low recruitment of juvenile trees to the adult stage. Climate change simulations using Maximum Entropy Algorithm (Maxent) revealed that future temperature increases would lead to significant reductions (41–100%) in baobab suitable habitats due to range contraction. The intensive harvesting of baobab leaves, branches and bark and lack of conversation practices as indicated by local communities, in combination with the risk of local extinction under future climate warming constitute serious threats for the viability of the species in western Tigray. The results suggest immediate interventions, such as planting baobab at up to 65 m higher in altitude, designing appropriate leaf and bark harvest strategies and protecting seedlings from livestock, will help guarantee the persistence of the species populations. Keywords: Non-timber forest products (NTFPs), Size-class distribution, Maximum entropy (Maxent), Overgrazing, Local ecological knowledge, Consensus value
... Indeed, climate changes expected cause an increase in temperature seasonality and mean annual temperature, as well as an increase precipitation during the rainy season and a decrease in rainfall during the dry season in Madagascar (Tadross et al., 2008;Vieilledent et al., 2016). The same trend, i.e. stability or increase in geographical distribution, could also occur for some deciduous perennial and aridity-adapted species in Mongolia, China and Ethiopia Noulèkoun et al., 2017;Qin et al., 2020) and for baobab species adapted to very dry and hot areas (Adansonia grandidieri) in Madagascar (Vieilledent et al., 2013;Wan et al., 2021). ...
La diversité biologique est inégalement répartie sur la planète, étant majoritairement concentrée sur quelques points chauds appelées « hotspots de la biodiversité ». La région Sud-Ouest de l’océan Indien (SOOI) figure parmi les régions prioritaires pour la conservation de la biodiversité et des orchidées. Leader mondial en production de gousses de vanille, cette région abrite également une diversité importante en espèces aphylles endémiques appartenant au genre Vanilla Plum. ex. Miller (Orchidaceae), majoritairement distribuées à Madagascar. Les vanilliers aphylles, par leur capacité d’adaptation à la sècheresse et leurs potentialités médicinales, présentent un intérêt économique et scientifique majeur. Ces espèces forment un groupe monophylétique différencié récemment à partir d’un ancêtre folié africain. Elles ont des traits morphologiques similaires et sont indissociables à partir de marqueurs chloroplastiques, rendant leur statut taxonomique douteux. A Madagascar, elles sont réparties principalement dans les forêts sèches de la côte Ouest, classées parmi les écosystèmes les plus menacés de l’île. Dans l’objectif de contribuer à leur conservation, des prospections suivies d’échantillonnages ont été réalisés dans plusieurs localités de Madagascar. Ensuite, une approche intégrative combinant la génétique, la biologie et l’écologie a été réalisée pour résoudre la taxonomie de ces espèces et déterminer leur statut de conservation. D’après les analyses des données microsatellites et morphologiques, la différenciation des sept groupes génétiques identifiés à Madagascar résulterait de plusieurs facteurs dont principalement les barrières géographiques (rivières), l’isolement par les facteurs environnementaux (IBE) (température, élévation, pH du sol) fortement corrélé à la géographie (IBD), et l’isolement par adaptation (IBA) de traits floraux (résultant soit de l’IBE soit d’une sélection divergente par les pollinisateurs). L’étude taxonomique intégrative (phylogénie ITS, analyse populationnelle microsatellite et morphologique) divise les vanilliers du SOOI en deux grands clades : espèces à fleurs blanches versus espèces à fleurs jaunes. Dans le clade des espèces à fleurs blanches, V. decaryana (Madagascar) et V. roscheri (Afrique de l’Est) forment chacune un groupe monophylétique tandis que V. madagascariensis (Madagascar), V. bosseri (Madagascar) et V. phalaenopsis (Seychelles) apparaissent conspécifiques (ITS), mais récemment différenciées (microsatellites). L’étude révèle également la présence de deux nouvelles espèces, réparties à l’Est, qui ont été nommées V. allorgii et V. atsinananensis et décrites. Dans le clade des aphylles à fleurs jaunes, V. perrieri (Madagascar) semble s’être différenciée de V. humblotii (Madagascar et Comores). La configuration de l’arbre ITS soutient une origine malgache de ces deux grands clades, suivie de trois colonisations indépendantes vers l’Afrique de l’Est, l’Archipel des Comores et les Seychelles. D’après les tests de pollinisations réalisés, les espèces aphylles sont auto-compatibles mais dépendent de pollinisateurs et peuvent se croiser entre elles. Les analyses de la diversité génétique, de la biologie de la reproduction et la modélisation spatiale et temporelle des niches écologiques des sept espèces malgaches suggèrent que V. allorgii et V. atsinananensis sont menacées respectivement par la faible densité des populations et une perte d’interaction avec les pollinisateurs. La fragmentation des populations naturelles de V. decaryana a entrainé une perte de diversité génétique ainsi qu’une forte consanguinité. V. madagascariensis et V. humblotii ont des zones de distribution restreintes dans le Nord, pouvant menacer leur survie à long terme. V. perrieri et V. bosseri semblent être les moins vulnérables car largement réparties le long de la côte Ouest. Des mesures de conservation ex situ et in situ sont proposées pour optimiser la conservation de ces vanilliers sauvages à Madagascar.
... Concerning the islands of the Union of the Comoros, (Grande Comore, Anjouan and Mohéli), the inventories were carried out between January 2009 and July 2010 and continuously updated until 2016. They relied on preliminary localisation of the baobabs by photo-interpretation of very high spatial resolution satellite imagery based on and adapted from the method described by Vieilledent et al. (2013) using Quickbird images with a 61 cm spatial resolution. ...
This study aims to provide some information about the area of presence and geographical breakdown of baobabs belonging to the Adansonia digitata species on the four Comoro Islands. Two of the eight known species of baobabs in the world are present in the Comoro Islands. Whilst they have asset value, a thorough study of their geographical distribution has yet to be produced and there is very little existing action to protect and conserve the asset. An inventory of the A. digitata populations on the islands (Grande Comore, Mohéli, Anjouan and Mayotte) and islets of the archipelago was carried out. From this, it was possible to map the geographical breakdown and analyse the spacial distribution of the baobabs. Their distribution seems to be strongly associated to their proximity to the coastline, suggesting the seeds are dispersed by marine hydrochory. The ecological status of this species based on IUCN status assessment, is known from the threats and pressures incurred and its distribution according to their ecological preferences. The species is categorized as Endangered (ER). The data from this study should contribute to improved management and conservation of the Adansonia species in the Comoros, a growing requirement in the light of concerns about anthropogenic pressure.
... We created the climate change threat maps assuming that all selected species react in the same way to climatic conditions becoming less suitable. Also differences in plasticity of functional traits [59], in genetic variability [60], in seed dispersal [61], etc., can play an important role in vulnerability of species to a rapidly changing environment. Due to the existing complexity of the multi-threat approach, we decided not to consider this additional aspect in our analysis. ...
Over the last decades agroforestry parklands in Burkina Faso have come under increasing demographic as well as climatic pressures, which are threatening indigenous tree species that contribute substantially to income generation and nutrition in rural households. Analyzing the threats as well as the species vulnerability to them is fundamental for priority setting in conservation planning. Guided by literature and local experts we selected 16 important food tree species (
... Due to the model's effectiveness, it has been widely used in biodiversity (especially for endangered species) conservation [47][48][49][50][51], invasive species control [52,53], as well as nature reserve planning and management [54][55][56]. It has also been applied to reconstruct habitat shifts of individual species or vegetation during the last glacial period, and simulate how paleoclimatic fluctuations have influenced the present distribution [57][58][59], predict the potential distribution in the future, find conservation gaps, and guide protection management [60][61][62]. ...
White pines (Pinus subsect. Strobus) play important roles in forest ecosystems in the Northern Hemisphere. Species of this group are narrowly distributed or endangered in China. In this study, we used a species distribution model (SDM) to project and predict the distribution patterns of the 12 species of Chinese white pine under a variety of paleoclimatic and future climate change scenarios based on 39 high-resolution environmental variables and 1459 distribution records. We also computed the centroid shift, range expansion/contraction, and suitability change of the current distribution area to assess the potential risk to each species in the future. The modeling results revealed that the suitable habitat of each species is consistent with but slightly larger than its actual distribution range and that temperature, precipitation, and UV radiation are important determining factors for the distribution of different white pine species. The results indicate that the Last Glacial Maximum (LGM) greatly affected the current distribution of the Chinese white pine species. Additionally, it was predicted that under the future climate change scenarios, there will be a reduction in the area of habitats suitable for P. armandii, P. morrisonicola, and P. mastersiana. Furthermore, some of the current distribution sites of P. armandii, P. kwangtungensis, P. mastersiana, P. morrisonicola, P. sibirica, and P. wallichiana were predicted to become more unsuitable under these scenarios. These results indicate that some Chinese white pine species, such as P. armandii, P. morrisonicola, and P. mastersiana, may have a very high risk of population shrinkage in the future. Overall, this study provided relevant data for the long-term conservation (both in situ and ex situ) and sustainable management of Chinese white pine species.
... However, in (2008) estimates that less than 10 % of the potential inherent in its existing baobabs are utilized, but this statement needs verification, particularly if commercial use is to be promoted for improving livelihoods of local communities. Aerial tree identification and mapping of baobab populations, as already suggested by Wickens (1966), in combination with ground referencing as conducted by Vieilledent et al. (2013) on Malagasy baobab species may help to assess the sizes and distributions of baobab populations in Sudan and Kenya. ...
... For Kenya, on the other hand, NRC (2008) estimates that less than 10 % of the potential inherent in its existing baobabs are utilized, but this statement needs verification, particularly if commercial use is to be promoted for improving livelihoods of local communities. Aerial tree identification and mapping of baobab populations, as already suggested by Wickens (1966), in combination with ground referencing as conducted by Vieilledent et al. (2013) on Malagasy baobab species may help to assess the sizes and distributions of baobab populations in Sudan and Kenya. ...
An inventory of flora in Um Dom Island (Khartoum State),
... The CNFA method is also able to make direct comparisons of climate change vulnerability among species. Compared with previous correlative approaches used to assess the vulnerability of species to climate change (Cole et al., 2011;Vieilledent et al., 2013), CNFA avoids uncertainties arising from differences in methods and models used to predict species distribution (Pacifici et al., 2015;Pearson et al., 2006;Rinnan & Lawler, 2019). Moreover, unlike trait-based vulnerability assessment approaches (Foden et al., 2013;Williams et al., 2008), CNFA is not limited by gaps in knowledge of individual species' traits (Foden et al., 2013;Rinnan & Lawler, 2019;Thomas et al., 2011). ...
High‐mountain areas such as the Tibeto‐Himalayan region (THR) host cold‐adapted biota expected to be sensitive to anthropogenic climate change. Meconopsis is a representative endangered genus confined to alpine meadow or subnival habitats in the THR. We used climate‐niche factor analysis to study the vulnerability of ten Meconopsis species to climate change, comparing current climate (representative of 1960–1990) to future climate scenarios (2070: average 2061–2080). For these ten Meconopsis species, we then identified potential future climate refugia and determined optimal routes for each species to disperse to the proposed refugia. Our results indicate that for the ten Meconopsis species, the regions with low vulnerability to climate change in the THR are the central Qinghai‐Tibet Plateau, the Hengduan Mountains (HDM), the eastern Himalayas, and the West Qinlin Mountain (WQL), and can be considered potential future climate refugia. Under future climate change, we found for the ten Meconopsis species potential dispersal routes to three of the four identified refugia: the HDM, the eastern Himalayas, and the WQL. Our results suggest that past refugia on the THR will also be the future climate refugia for the ten Meconopsis species, and these species may potentially persist in multiple future climate refugia, likely reducing risks from climate change. Furthermore, climate change may affect the threat ranking of Red Listed Species for Meconopsis species, as Least Concern species were estimated to become more vulnerable to climate change than the only Near Threatened species.
... With an appropriate mitigation plan, the increase in rainfall could be beneficial for the south and southwestern regions which have been experiencing prolonged drought. On the other hand, previous studies found that the warm and wet conditions have important biological implications, including extinction risk of some endemic species (Hannah et al 2008, Vieilledent et al 2013. Recently, Vieilledent et al (2016) showed that the projected climate change signals over Madagascar could also lead to a decrease in the tropical forest carbon stock in the country, hence enhanced emission of carbon into the atmosphere. ...
Outputs from 25 regional climate models within the coordinated regional downscaling experiments—Africa are used to assess the impacts of the 1.5°C and 2°C global warming levels (GWLs) over Madagascar. A robust increase in the annual mean temperature ranging from 0.9°C to 1.2°C (1.3°C–1.8°C) is projected in the 1.5°C (2°C) GWL. The west and southwestern parts of the island display the highest rise in temperature. On the other hand, the changes in rainfall signals depend on the location, the months within the rain season and the warming level with the models showing a large uncertainty in the signal of changes. During early summer, the west and southwest regions exhibit an increase in total rainfall accompanied with more wet spell days and excessive amounts of extreme rainfall. In contrast, the east and the north are characterized by a deficit in total rainfall and wet spell days while the maximum number of dry spells increase. The change signals are more pronounced in the 2°C GWL. From January to April, an overall increase in total and extreme rainfall is projected over the island. The two warming levels agree on the delay in the rainfall onset and shortening of the rainfall season with the 2°C GWL depicting more modest changes in the west and southern parts of the country compared to that of 1.5 °C GWL. These results have important implications not only for the development of the country but also for the endemic biodiversity which is already suffering from the impacts of climate change.
We extended our research on the architecture, growth and age of trees belonging to the genus Adansonia, by starting to investigate large individuals of the most widespread Malagasy species. Our research also intends to identify the oldest baobabs of Madagascar. Here we present results of the radiocarbon investigation of the two most representative Adansonia rubrostipa (fony baobab) specimens, which are located in south-western Madagascar, in the Tsimanampetsotse National Park. We found that the fony baobab called "Grandmother" consists of 3 perfectly fused stems of different ages. The radiocarbon date of the oldest sample was found to be 1136 ± 16 BP. We estimated that the oldest part of this tree, which is mainly hollow, has an age close to 1,600 yr. This value is comparable to the age of the oldest Adansonia digitata (African baobab) specimens. By its age, the Grandmother is a major candidate for the oldest baobab of Madagascar. The second investigated specimen, called the "polygamous baobab", consists of 6 partially fused stems of different ages. According to dating results, this fony baobab is 1,000 yr old. This research is the first investigation of the structure and age of Malagasy baobabs.
Global change is expected to impact on the distribution and abundance of forests. Spain represents the southwestern limit of distribution for several types of deciduous forests and, as part of the Mediterranean Basin, it has all the characteristics to be affected by climate change. This study analyses the effects of climate change on habitat suitability and vulnerability in four categories of deciduous forests: Fagus sylvatica L., Quercus petraea (Matt.) Leibl., Quercus robur L. and Betula celtiberica Rothm. and Vasc. The approach combines an ensemble platform for species distribution models (SDMs) using three algorithms applied to four global circulation models (GCMs) driven by two representative concentration pathways (RCPs). Bioclimatic, biogeographic, soil and topographic variables were taken into consideration as predictors to build 320 single distribution models. Ensemble-forecasting models were then produced for each forest category and RCPs by computing a consensus of single-model projections. The adapted proposal of the Intergovernmental Panel on Climate Change (IPCC) was also applied to deal with the uncertainty and notify the likelihood of the outcomes.
The results revealed generalized losses in habitat suitability compared to current conditions for all the forest categories, which were more drastic for the RCP 8.5 emission pathway. Exceptions worth noting are forests of Fagus sylvatica (likelihood 25%-50%) and Quercus robur (likelihood 75%-100%) in the Orocantabrian biogeographic subprovince, and Quercus petraea formations in the Cantabrian Atlantic subprovince (likelihood 25%-50%). Betula celtiberica would suffer the largest losses of habitat suitability under the climate change scenarios analysed. The vulnerability analysis confirmed that the deciduous formations least affected by climate change in future will be the Orocantabrian forests, while the Pyrenean and Oroiberian communities are the most vulnerable.
The models developed in this study provide decision-makers with basic information and a useful tool for designing plans for the conservation and management of these forests in order to mitigate the impact of climate change. The study also highlights the importance and usefulness of conducting analyses at the biogeographic level, since the effects of climate change may be different and require management and conservation policies at local level.
It is commonly accepted that species should move toward higher elevations and latitudes to track shifting isotherms as climate warms. However, temperature might not be the only limiting factor determining species distribution. Species might move to opposite directions to track changes in other climatic variables. Here, we used an extensive occurrence dataset and an ensemble modelling approach to model the climatic niche and to predict the distribution of the seven baobab species (genus Adansonia) present in Madagascar. Using climatic projections from three global circulation models, we predicted species’ future distribution and extinction risk for 2055 and 2085 under two representative concentration pathways (RCPs) and two dispersal scenarios. We disentangled the role of each climatic variable in explaining species range shift looking at relative variable importance and future climatic anomalies. Four baobab species (A. rubrostipa, A. madagascariensis, A. perrieri¸ and A. suarezensis) could experience a severe range contraction in the future (> 70% for year 2085 under RCP 8.5, assuming a zero‐dispersal hypothesis). For three out of the four threatened species, range contraction was mainly explained by an increase in temperature seasonality, especially in the North of Madagascar, where they are currently distributed. In tropical regions, where species are commonly adapted to low seasonality, we found that temperature seasonality will generally increase. It is thus very likely that many species in the tropics will be forced to move equatorward to avoid an increase in temperature seasonality. Yet, several ecological (e.g. equatorial limit, or unsuitable deforested habitat) or geographical barriers (absence of lands) could prevent species to move equatorward, thus increasing the extinction risk of many tropical species, like endemic baobab species in Madagascar.
This study investigated the Ecological Distribution and Abundance of Sausage tree (Kigelia africana) in Murchison Falls National Park. Kigelia africana is one of the important Non-Timber Forest Products (NTFPs), currently providing a range of ecological and socioeconomic benefits. There was a need to have a clear understanding of the distribution and abundance of the species to guide future plans for its conservation in-situ, in order to realize its full potential for sustainable exploitation. A comparison of densities, distribution patterns, structure, stem conditions in the studied area of Murchison falls national park was done. We carried out field data collection between February and April 2017. Line transect was used to sample Kigelia africana in. The diameter at breast height (dbh) of adult and sub-adult trees, height of adults, sub adults and their stem conditions, number of fruits on each fruiting sausage tree were recorded. The results revealed a significant difference in the sausage tree abundance and distribution with (24%) at distance of 500m as highest percentage and lowest abundance (3%) at distance of 700m along the transect and trees with highest fruit abundance at 42.2% (100-199) and lowest at 2% (0-4) The study identified significant differences in the dbh-size ranges with highest dbh of 36.1% (201-300) and lowest dbh of 2% 601-700, 701-800). The bell-shaped distribution curve in dbh size-rangeshad50.3% damaged stems compared to 49.7% intact. Poor seedling survival resulting primarily from herbivory, human activities and climate variability hampers sausage treemobilization. Considering the poor mobilization due to the above factors, the potential for commercialization of sausage trees in the region may not be viable. Therefore, active planting in undisturbed areas, protection of seedlings from livestock coupled with community awareness are vital to ensure better management of sausage trees, so that effective commercialization and subsistence use is realized and sustainable.
en With many species predicted to respond to a changing climate by shifting their distribution to climatically suitable areas, the effectiveness of static protected areas (PAs) is in question. The Madagascan PA network area has quadrupled over the past 15 years, and, although conservation planning techniques were employed to prioritise suitable areas for protection during this process, climate change impacts were not considered. We make use of species distribution models for 750 Madagascan vertebrate species to assess the potential impacts of climate change on (1) species richness across Madagascar, (2) species gain, loss and turnover in Madagascar's PAs and (3) PA network representativeness. Results indicate that Madagascar is predicted to experience substantial shifts in species richness, with most PAs predicted to experience high rates of species turnover. Provided there are no barriers to species movements, the representativeness of the current PA network will remain high for the species that are predicted to survive changes in climate by 2070, suggesting that little benefit will be gained from establishing new PAs. However, this rests on the assumption of mobility through areas currently characterised by fragmentation and anthropogenic activity, something that will require considerable expansion in conservation efforts in order to achieve.
Résumé
fr Il est prévu que de nombreuses espèces réagissent au changement climatique en déplaçant leurs populations vers des zones climatiquement adaptées. De ce fait, l'efficacité des aires protégées statiques (AP) est remise en question. La superficie du réseau des AP malgaches a quadruplé au cours des 15 dernières années et, bien que des techniques de planification de la conservation aient été employées pour privilégier les zones à protéger adéquates pendant ce processus, les impacts du changement climatique n'ont pas été pris en compte. Nous utilisons des modèles de répartition d'espèces pour 750 espèces de vertébrés malgaches afin d'évaluer les impacts potentiels du changement climatique sur (1) la richesse en espèces de Madagascar, (2) le gain, la perte et le renouvellement des espèces dans les AP de Madagascar, et (3) la représentativité du réseau d'AP. Les résultats indiquent que Madagascar devrait connaître des changements importants en termes de richesse en espèces et que la plupart des AP devraient connaître des taux élevés de renouvellement des espèces. Si aucun obstacle n'affecte les mouvements des espèces, la représentativité du réseau actuel d'AP restera élevée pour les espèces qui devraient survivre aux changements climatiques d'ici 2070, ce qui suggère que peu d'avantages seront tirés de l'établissement de nouvelles AP. Cependant, cela repose sur l'hypothèse d'une mobilité au sein de zones actuellement caractérisées par la fragmentation et l'activité anthropique, ce qui nécessitera une augmentation considérable des efforts de conservation pour y parvenir.
Species distribution models (SDMs) are efficient tools for modeling species geographic distribution under climate change scenarios. Due to differences among predictions of these models, their results are combined using consensus methods to form an ensemble model. This paper provides an optimal combination of the common SDMs according to accuracy and correlation to model the climatic suitability of Quercus brantii in the west of Iran and projects it into the years 2050 and 2070. This is done using 1000 samples of the species presence and absence, 4 bioclimatic variables related to temperature and precipitation, and 10 modeling algorithms. An ensemble combination of Global Climate Models (GCMs) and 4 optimistic and pessimistic greenhouse-gas emissions scenarios were utilized to identify the climatically suitable areas in the years 2050 and 2070. These models were combined using three common statistics, including mean, median, and weighted mean. The predictive accuracies of the single-models and the consensus methods were assessed using the area under the curve (AUC) metric that validates the acceptable performance of the 9 out of the 10 models studied. Applying the genetic algorithm, the best combination of the models was selected including 4 algorithms with accuracy and correlation equal 0.95 and 0.30 respectively. The results show that the Random Forest (RF) model causes less error in the ensemble model and also compensates other models' errors more. Projections into the years 2050 and 2070 showed that in both time periods and under all scenarios, changes will occur in the spatial distribution of this species, and the most severe one would be a 55.6% loss under the most pessimistic scenario in 2070.
Assessing the genetic diversity of species and populations is critical for evaluating extinction vulnerability and provides important information for identifying populations of concern and/or those that should be targeted for breeding material. Baobabs (Adansonia L.) are botanical icons for conservation, with increasing attention regarding their threatened status from both scientists and non-scientists alike. Baobabs are of particular interest especially in Madagascar, where six of the eight species are endemic, and three are listed as Endangered or Critically Endangered by the International Union for Conservation of Nature (IUCN). Although A. madagascariensis Baill., A. rubrostipa Jum. & H. Perrier and A. za Baill. are more widespread and classified by IUCN as Least Concern, they show regional variation, which may reflect hidden genetic diversity or even the existence of cryptic species. Here we assess the genetic diversity of the Malagasy baobabs to serve as a basis for future conservation and management planning. Our study used a targeted sequence capture approach (hybrid enrichment) to obtain hundreds of low-copy nuclear loci with phased alleles to assess genetic diversity in the six species and their major regional subpopulations. We discuss the implications of proper delineation of species taxonomy for management issues associated with conservation. We hope such genetic information will guide more targeted population genetic assessments and inform conservation and management efforts, including identification of isolated or disjunct populations that may warrant targeted actions.
This study investigated the Ecological Distribution and Abundance of Sausage tree (Kigelia africana) in Murchison Falls National Park. Kigelia africana is one of the important Non-Timber Forest Products (NTFPs), currently providing a range of ecological and socio-economic benefits. There was a need to have a clear understanding of the distribution and abundance of the species to guide future plans for its conservation in-situ, in order to realize its full potential for sustainable exploitation. A comparison of densities, distribution patterns, structure, stem conditions in the studied area of Murchison falls national park was done. We carried out field data collection between February and April 2017. Line transect was used to sample Kigelia africana in. The diameter at breast height (dbh) of adult and sub-adult trees, height of adults, sub adults and their stem conditions, number of fruits on each fruiting sausage tree were recorded. The results revealed a significant difference in the sausage tree abundance and distribution with (24%) at distance of 500m as highest percentage and lowest abundance (3%) at distance of 700m along the transect and trees with highest fruit abundance at 42.2% (100-199) and lowest at 2% (0-4) The study identified significant differences in the dbh-size ranges with highest dbh of 36.1% (201-300) and lowest dbh of 2% 601-700, 701-800). The bell-shaped distribution curve in dbh size-rangeshad50.3% damaged stems compared to 49.7% intact. Poor seedling survival resulting primarily from herbivory, human activities and climate variability hampers sausage treemobilization. Considering the poor mobilization due to the above factors, the potential for commercialization of sausage trees in the region may not be viable. Therefore, active planting in undisturbed areas, protection of seedlings from livestock coupled with community awareness are vital to ensure better management of sausage trees, so that effective commercialization and subsistence use is realized and sustainable.
The baobabs (Bombacaceae: Adansonia) are tropical trees native to Africa, Australia, and Madagascar but dispersed widely by humans. The members of the genus are united by several derived characters that serve to distinguish them from other Bombacaceae, including a characteristic, indehiscent fruit with reniform seeds and a powdery pulp. The systematics of Adansonia is revised, with three sections and eight species being recognized. The support for each species is discussed in the context of the "Genealogical Species Concept." Several nomenclatural problems are resolved, and a new combination, A. gibbosa (A. Cunn.) Guymer ex D. Baum, is made. In addition, the ecology, ethnobotany, and conservation status of Adansonia is summarized, focusing especially on the poorly known Malagasy and Australian species.
This report provides background information on changes in historical climate observed at sites within Madagascar and the changes, due to anthropogenic climate change, expected towards the middle of the 21 st century. As such it draws on observations, downscaled climate change projections, reviewed literature and the 4 th Intergovernmental Panel on Climate Change (IPCC) report (AR4). 1 Background Madagascar's climate is highly varied, largely due to its geographical position in the Indian Ocean, its wide range of altitudes and different microclimates. Most rain falls during summer (November – April) with rainfall during winter (May – October) restricted to the southern and eastern coasts. Rainfall over the east coast is largely a product of easterly trade winds that bring moisture to its shores during much of the year. The steep topography causes the warm and moist air masses to rise, producing rainfall and leaving less moisture for rainfall further west. The central uplands and drier western regions receive rainfall during summer, mostly through convective activity and thunderstorms linked to the Inter-Tropical Convergence Zone (ITCZ), which lies across the northern parts of Madagascar during this time of year. During winter mid-latitude storms pass to the south of Madagascar which, when in a northerly position, can bring lower temperatures and rain to the southern parts of the country. This rainfall may be enhanced in regions of steep topography but remains small with much of the region receiving on average less than 800 mm each year. This contrasts sharply with regions in the northeast of the country which on average receive more than 3500 mm of annual rainfall Mean annual temperatures are greatest along the dry west coast and coolest over the central upland plateaux. Temperature variations depend on location and altitude with minimum temperatures in winter on average less than 5 °C during June and July in the highlands (though some days reach below freezing). Maximum temperatures are highest in spring (October and November) over the west coast, on average greater than 36 °C in some regions, though some days are significantly hotter.
Madagascar is a critical priority for interna- tional conservation efforts, based on almost unparalleled levels of endemism, species diversity, and human threat. Field research conducted over the past two decades has greatly expanded knowledge of the island's biota, making it difficult for any single research team to main- tain up to date estimates of biodiversity and endemism across taxonomic groups. The recent publication of The Natural History of Madagascar, a synthesis by nearly 300 contributors from a wide range of disciplines, provides the means to update these estimates. Here, we summa- rize biodiversity information presented in the volume by providing revised estimates of species richness, endemism, and state of knowledge of a wide variety of taxonomic groups occurring on the island.
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Anthropogenic deforestation in tropical countries is responsible for a significant part of global carbon dioxide emissions in the atmosphere. To plan efficient climate change mitigation programs (such as REDD+, Reducing Emissions from Deforestation and forest Degradation), reliable forecasts of deforestation and carbon dioxide emissions are necessary. Although population density has been recognized as a key factor in tropical deforestation, current methods of prediction do not allow the population explosion that is occurring in many tropical developing countries to be taken into account. Here, we propose an innovative approach using novel computational and statistical tools, including R/GRASS scripts and the new phcfM R package, to model the intensity and location of deforestation including the effect of population density. We used the model to forecast anthropogenic deforestation and carbon dioxide emissions in five large study areas in the humid and spiny-dry forests of Madagascar. Using our approach, we were able to demonstrate that the current rapid population growth in Madagascar (+3.39% per year) will significantly increase the intensity of deforestation by 2030 (up to +1.17% per year in densely populated areas). We estimated the carbon dioxide emissions associated with the loss of aboveground biomass to be of 2.24 and 0.26 tons per hectare and per year in the humid and spiny-dry forest, respectively. Our models showed better predictive ability than previous deforestation models (the figure of merit ranged from 10 to 23). We recommend this approach to reduce the uncertainty associated with deforestation forecasts. We also underline the risk of an increase in the speed of deforestation in the short term in tropical developing countries undergoing rapid population expansion.
a b s t r a c t The extinctions of keystone megafauna during the Pleistocene and Holocene continue to affect extant species and ecosystems. This is particularly acute in southern and western Madagascar where two now extinct species of giant tortoises were once amongst the most dominant herbivores. The extinct giant tortoises are likely to have influenced ecosystem processes by being effective dispersers of large seeds, keeping the understorey open, cycling nutrients, and indirectly regulating fire regimes. As a result of their extinction, ecological interactions and ecosystems have been altered. Given that there is evidence that the extant Aldabran giant tortoise, Aldabrachelys gigantea, is closely related to at least one of these Madagascan giant tortoises, Aldabrachelys abrupta, we propose using captive Aldabran giant tortoises to restore missing ecological functions. This ambitious approach will represent the first continental island restoration project with a surviving lineage of now extinct, endemic megafauna. Translocation of this megafauna species could be a pragmatic and cost-effective tool to contribute to halting the ongoing extinction processes in parts of western and southern Madagascar, and would further understanding of the role of these species in pre-human Madagascan ecosystems.
Tropical deforestation is a key contributor to species extinction and climate change, yet the extent of tropical forests and their rate of destruction and degradation through fragmentation remain poorly known. Madagascar's forests are among the most biologically rich and unique in the world but, in spite of longstanding concern about their destruction, past estimates of forest cover and deforestation have varied widely. Analysis of aerial photographs (c. 1953) and Landsat images (c. 1973, c. 1990 and c. 2000) indicates that forest cover decreased by almost 40% from the 1950s to c. 2000, with a reduction in 'core forest' > 1 km from a non-forest edge of almost 80%. This forest destruction and degradation threaten thousands of species with extinction. Country-wide coverage of high-resolution validated forest cover and deforestation data enables the precise monitoring of trends in habitat extent and fragmentation critical for assessment of species' conservation status.
Species distribution modelling has been widely applied in order to assess the potential impacts of climate change on biodiversity. Many methodological decisions, taken during the modelling process and forecasts, may, however, lead to a large variability in the assessment of future impacts. Using measures of species range change and turnover, the potential impacts of climate change on French stream fish species and assemblages were evaluated. Our main focus was to quantify the uncertainty in the projections of these impacts arising from four sources of uncertainty: initial datasets (Data), statistical methods [species distribution models (SDM)], general circulation models (GCM), and gas emission scenarios (GES). Several modalities of the aforementioned uncertainty sources were combined in an ensemble forecasting framework resulting in 8400 different projections. The variance explained by each source was then extracted from this whole ensemble of projections. Overall, SDM contributed to the largest variation in projections, followed by GCM, whose contribution increased over time equalling almost the proportion of variance explained by SDM in 2080. Data and GES had little influence on the variability in projections. Future projections of range change were more consistent for species with a large geographical extent (i.e., distribution along latitudinal or stream gradients) or with restricted environmental requirements (i.e., small thermal or elevation ranges). Variability in projections of turnover was spatially structured at the scale of France, indicating that certain particular geographical areas should be considered with care when projecting the potential impacts of climate change. The results of this study, therefore, emphasized that particular attention should be paid to the use of predictions ensembles resulting from the application of several statistical methods and climate models. Moreover, forecasted impacts of climate change should always be provided with an assessment of their uncertainty, so that management and conservation decisions can be taken in the full knowledge of their reliability.
Aim To examine the impacts of climate change on endemic birds, which are of global significance for conservation, on a continent with few such assessments. We specifically assess projected range changes in relation to the Important Bird Areas (IBAs) network and assess the possible consequences for conservation.
Location South Africa, Lesotho and Swaziland.
Methods The newly emerging ensemble modelling approach is used with 50 species, four climate change models for the period 2070–2100 and eight bioclimatic niche models in the statistical package biomod. Model evaluation is done using the receiver operating characteristic and the recently introduced true skill statistic. Future projections are made considering two extreme assumptions: species have full dispersal ability and species have no dispersal ability. A consensus forecast is identified using principal components analysis. This forecast is interpreted in terms of the IBA network. An irreplaceability analysis is used to highlight priority IBAs for conservation attention in terms of climate change.
Results The majority of species (62%) are predicted to lose climatically suitable space. Five species lose at least 85% of their climatically suitable space. Many IBAs lose species (41%; 47 IBAs) and show high rates of species turnover of more than 50% (77%; 95 IBAs). Highly irreplaceable regions for endemic species become highly localized under climate change, meaning that the endemic species analysed here experience similar range contractions to maintain climate niches.
Main conclusions The South African IBAs network is likely to become less effective for conserving endemic birds under climate change. The irreplaceability analysis identified key refugia for endemic species under climate change, but many of these areas are not currently IBAs. In addition, many of these high-priority areas that are IBAs fall outside the current formal protected areas network.
BIOMOD is a computer platform for ensemble forecasting of species distributions, enabling the treatment of a range of methodological uncertainties in models and the examination of species-environment relationships. BIOMOD includes the ability to model species distributions with several techniques, test models with a wide range of approaches, project species distributions into different environmental conditions (e.g. climate or land use change scenarios) and dispersal functions. It allows assessing species temporal turnover, plot species response curves, and test the strength of species interactions with predictor variables. BIOMOD is implemented in R and is a freeware, open source, package.
Aim Techniques that predict species potential distributions by combining observed occurrence records with environmental variables show much potential for application across a range of biogeographical analyses. Some of the most promising applications relate to species for which occurrence records are scarce, due to cryptic habits, locally restricted distributions or low sampling effort. However, the minimum sample sizes required to yield useful predictions remain difficult to determine. Here we developed and tested a novel jackknife validation approach to assess the ability to predict species occurrence when fewer than 25 occurrence records are available.
At the 5th World Parks Congress, held in Durban, South Africa in 2003, the President of Madagascar committed his government
to tripling the country’s protected zones over the next 5years. The announcement reflected a desire to combine rapid conservation
efforts with sustainable development. Conservationists in Madagascar focused their attention on the endemic baobab tree, Adansonia grandidieri. This paper aims to identify the contradictions between the political emergency of the biodiversity conservation effort and
local development needs. Eighty-three semi-structured interviews were conducted in two villages near the protected area of
“Baobab Alley” in the Menabe region. Malagasy conservationists believed the area’s protected status would benefit the local
economy through eco-tourism. However, the conservation actions undertaken there display limited understanding of local dynamics
and conflict with farmers’ needs. To protect the baobabs, the government has prohibited rice cultivation without providing
compensation. We show that the multifunctional baobab tree is integrated into an agroforestry system and protected by farmers.
Based on these results, we address the issue of how to combine conservation and local development objectives through the involvement
of farmers and the recognition of local knowledge in tree management. We also demonstrate that an emergency approach to conservation
is not conducive to the successful integration of conservation and development.
Invasive species are known to influence the structure and function of invaded ecological communities, and preventive measures
appear to be the most efficient means of controlling these effects. However, management of biological invasions requires use
of adequate tools to understand and predict invasion patterns in recently introduced areas. The present study: (1) estimates
the potential geographic distribution and ecological requirements of the Argentine ant (Linepithema humile Mayr), one of the most conspicuous invasive species throughout the world, in the Iberian Peninsula using ecological niche
modeling, and (2) provides new insights into the process of selection of consensual areas among predictions from several modeling
methodologies. Ecological niche models were developed using 5 modeling techniques: generalized linear models (GLM), generalized
additive models (GAM), generalized boosted models (GBM), Genetic Algorithm for Rule-Set Prediction (GARP), and Maximum Entropy
(Maxent). Models for the eastern and western portions of the Iberian Peninsula were built using subsets of occurrence and
environmental data to investigate the potential for ecological niche differences between the invading populations. Our results
indicate geographic differences between predictions of different approaches, and the utility of ensemble predictions in identifying
areas of uncertainty regarding the species’ invasive potential. More generally, our models predict coastal areas and major
river corridors as highly suitable for Argentine ants, and indicate that western and eastern Iberian Peninsula populations
occupy similar environmental conditions.
Spatial fingerprints of climate change on biotic communities are usually associated with changes in the distribution of species at their latitudinal or altitudinal extremes. By comparing the altitudinal distribution of 171 forest plant species between 1905 and 1985 and 1986 and 2005 along the entire elevation range (0 to 2600 meters above sea level) in west Europe, we show that climate warming has resulted in a significant upward shift in species optimum elevation averaging 29 meters per decade. The shift is larger for species restricted to mountain habitats and for grassy species, which are characterized by faster population turnover. Our study shows that climate change affects the spatial core of the distributional range of plant species, in addition to their distributional margins, as previously reported.
We developed interpolated climate surfaces for global land areas (excluding Antarctica) at a spatial resolution of 30 arc s (often referred to as 1-km spatial resolution). The climate elements considered were monthly precipitation and mean, minimum, and maximum temperature. Input data were gathered from a variety of sources and, where possible, were restricted to records from the 1950-2000 period. We used the thin-plate smoothing spline algorithm implemented in the ANUSPLIN package for interpolation, using latitude, longitude, and elevation as independent variables. We quantified uncertainty arising from the input data and the interpolation by mapping weather station density, elevation bias in the weather stations, and elevation variation within grid cells and through data partitioning and cross validation. Elevation bias tended to be negative (stations lower than expected) at high latitudes but positive in the tropics. Uncertainty is highest in mountainous and in poorly sampled areas. Data partitioning showed high uncertainty of the surfaces on isolated islands, e.g. in the Pacific. Aggregating the elevation and climate data to 10 arc min resolution showed an enormous variation within grid cells, illustrating the value of high-resolution surfaces. A comparison with an existing data set at 10 arc min resolution showed overall agreement, but with significant variation in some regions. A comparison with two high-resolution data sets for the United States also identified areas with large local differences, particularly in mountainous areas. Compared to previous global climatologies, ours has the following advantages: the data are at a higher spatial resolution (400 times greater or more); more weather station records were used; improved elevation data were used; and more information about spatial patterns of uncertainty in the data is available. Owing to the overall low density of available climate stations, our surfaces do not capture of all variation that may occur at a resolution of 1 km, particularly of precipitation in mountainous areas. In future work, such variation might be captured through knowledge-based methods and inclusion of additional co-variates, particularly layers obtained through remote sensing.
With this third edition of Open Source GIS: A GRASS GIS Approach, we enter the new era of GRASS6, the first release that includes substantial new code developed by the International GRASS Development Team. The dramatic growth in open source software libraries has made the GRASS6 development more efficient, and has enhanced GRASS interoperability with a wide range of open source and proprietary geospatial tools. Thoroughly updated with material related to the GRASS 6, the third edition includes new sections on attribute database management and SQL support, vector networks analysis, lidar data processing and new graphical user interfaces. All chapters were updated with numerous practical examples using the first release of a comprehensive, state-of-the-art geospatial data set. Open Source GIS: A GRASS GIS Approach (third edition) preserves the continuity of previous editions by maintaining the proven book's structure and continues to target professional audience composed of researchers and practitioners in government and industry as well as graduate students interested in geospatial analysis and modeling. URL: http://www.grassbook.org/
Connectivity is a fundamental concept that is widely utilised in spatail ecology. The majority of connectivity measures used in the recent ecological literature only consider the nearest neighbour patch/population, or patches within a limited neighbourhood of the focal patch(a buffer). Meta-analysis suggests that studies using nearest neighbour connectivity measures are much less likely to find statistically significant effects of connectivity than studies that use more complex measures. Here we compare simple connectivity measures in their ability to predict colonisation events in two large and good-quality empirical data sets. The nearest neighbour distance to an occupied patch is found to be an inferior measure. Buffer meaaures do far better, but their performance is found to be sensitive to the estimate of buffer radius. For highly fragmented a habitats, the best and most consistent performance is found for a measure that takes into account the size of the focal patch and the sizes and distances to all potential source populations. When experimenting with reduced data sets, it was discovered that the nearest neighbour measures fail to find a statistically significant effect of connectivity for a large range of data set sizes for which the more complex measures still detect a highly significant effect. We conclude that the simplicity of a nearest neighbour measure is not an adequate compensation for poor performance.
Ecology Letters (2011) 14: 484–492
Europe has the world’s most extensive network of conservation areas. Conservation areas are selected without taking into account the effects of climate change. How effectively would such areas conserve biodiversity under climate change? We assess the effectiveness of protected areas and the Natura 2000 network in conserving a large proportion of European plant and terrestrial vertebrate species under climate change. We found that by 2080, 58 ± 2.6% of the species would lose suitable climate in protected areas, whereas losses affected 63 ± 2.1% of the species of European concern occurring in Natura 2000 areas. Protected areas are expected to retain climatic suitability for species better than unprotected areas (P < 0.001), but Natura 2000 areas retain climate suitability for species no better and sometimes less effectively than unprotected areas. The risk is high that ongoing efforts to conserve Europe’s biodiversity are jeopardized by climate change. New policies are required to avert this risk.
"Climate change presents unprecedented challenges for biological conservation. Agencies are increasingly looking to modeled projections of species’ distributions under future climates to inform management strategies. As government scientists with a responsibility to communicate the best available science to our policy colleagues, we question whether current modeling approaches and outputs are practically useful. Here, we synthesize conceptual problems with species distribution models (SDMs) associated with interspecific interactions, dispersal, ecological equilibria and time lags, evolution, and the sampling of niche space. Although projected SDMs have undoubtedly been critical in alerting us to the magnitude of climate change impacts, we conclude that until they offer insights that are more precise than what we can derive from basic ecological theory, we question their utility in deciding how to allocate scarce funds to large-scale conservation projects."
La carte des domaines végétaux établie par Humbert (1955), et plus récemment celle de la répartition actuelle de la végétation, dessinée à partir d'images satellites (Faramalala, 1988, 1995), sont acceptées comme indicatives des larges zones végétales de Madagascar. Ces cartes, superposées aux cartes géologiques et à celles des aires protégées, ont été analysées en utilisant les techniques du Système Informatique Géographique (SIG). La composition spécifique de la végétation primaire est fortement influencée par le type de substrat sur lequel elle est installée : la carte géologique de Besairie (1964) a donc été remodelée selon de larges catégories de roches susceptibles d'exercer une nette influence sur la composition de la végétation qu'elles supportent. La comparaison de la carte de la végétation primaire ("Remaining Primary Vegetation") et de la carte géologique simplifiée ("Simplified Geology"), conduit à présenter une carte de la distribution actuelle de la végétation primaire fondée sur la géologie ("Remaining Primary Vegetation classified by the Underlying Geology"). L'étendue actuelle de chaque grand type de végétation primaire est estimée. Une comparaison avec la carte des aires protégées a permis d'établir des graphiques et des statistiques qui montrent quels types de végétation sont bien représentés dans le système actuel des aires protégées, et ceux qui sont insuffisamment représentés. Ces cartes et ces analyses fournissent des données utiles à la planification et la gestion d'une conservation efficace de la biodiversité de Madagascar. (Résumé d'auteur)
Madagascar's imperilled biota are now experiencing the effects of a new threat—climate change ([Raxworthy et al . 2008][1]). With more than 90% endemism among plants, mammals, reptiles and amphibians, the stakes are high. The pristine landscapes that allowed this exceptional biodiversity to
Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a 'systematic trend'. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial 'sign-switching' responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates 'very high confidence' (as laid down by the IPCC) that climate change is already affecting living systems.
Hybridization between species is commonplace in plants, but is often seen as unnatural and unusual in animals. Here, I survey studies of natural interspecific hybridization in plants and a variety of animals. At least 25% of plant species and 10% of animal species, mostly the youngest species, are involved in hybridization and potential introgression with other species. Species in nature are often incompletely isolated for millions of years after their formation. Therefore, much evolution of eventual reproductive isolation can occur while nascent species are in gene-flow contact, in sympatry or parapatry, long after divergence begins. Although the relative importance of geographic isolation and gene flow in the origin of species is still unknown, many key processes involved in speciation, such as 'reinforcement' of post-mating isolation by the evolution of assortative mating, will have ample opportunity to occur in the presence of continuing gene flow. Today, DNA sequence data and other molecular methods are beginning to show that limited invasions of the genome are widespread, with potentially important consequences in evolutionary biology, speciation, biodiversity, and conservation.
The location of and threats to biodiversity are distributed unevenly, so prioritization is essential to minimize biodiversity
loss. To address this need, biodiversity conservation organizations have proposed nine templates of global priorities over
the past decade. Here, we review the concepts, methods, results, impacts, and challenges of these prioritizations of conservation
practice within the theoretical irreplaceability/vulnerability framework of systematic conservation planning. Most of the
templates prioritize highly irreplaceable regions; some are reactive (prioritizing high vulnerability), and others are proactive
(prioritizing low vulnerability). We hope this synthesis improves understanding of these prioritization approaches and that
it results in more efficient allocation of geographically flexible conservation funding.
Concern over implications of climate change for biodiversity has led to the use of bioclimatic models to forecast the range shifts of species under future climate-change scenarios. Recent studies have demonstrated that projections by alternative models can be so variable as to compromise their usefulness for guiding policy decisions. Here, we advocate the use of multiple models within an ensemble forecasting framework and describe alternative approaches to the analysis of bioclimatic ensembles, including bounding box, consensus and probabilistic techniques. We argue that, although improved accuracy can be delivered through the traditional tasks of trying to build better models with improved data, more robust forecasts can also be achieved if ensemble forecasts are produced and analysed appropriately.
First and only fully comprehensive account of all eight species of Adansonia Contains much new information Highly interesting for scientists, academics and laypeople This is the only comprehensive account of all eight species in the genus Adansonia. It describes the historical background from the late Roman period to the present. It covers the extraordinary variety of economic uses of baobabs, famous trees, folk traditions and mythology, art associations, life cycle, natural history, cultivation, conservation, distribution and ecology, and phytogeography. There are also appendices on vernacular names, gazetteer, economics, nutrition and forest mensuration. This book fills a gap in the botanical literature. It deals with a genus that has fascinated and intrigued scientists and lay persons for centuries. It will appeal to scientists and academics as well as tropical horticulturalists, conservationists and general interest readers. It includes all the available scientific information about each of the eight species, and contains a good deal of original research on the history, ethnobotany and biology of the genus. There is even a chapter devoted to areas where further research is required. © 2008 Springer Science + Business Media, B.V. All rights reserved.
With the rise of new powerful statistical techniques and GIS tools, the development of predictive habitat distribution models has rapidly increased in ecology. Such models are static and probabilistic in nature, since they statistically relate the geographical distribution of species or communities to their present environment. A wide array of models has been developed to cover aspects as diverse as biogeography, conservation biology, climate change research, and habitat or species management. In this paper, we present a review of predictive habitat distribution modeling. The variety of statistical techniques used is growing. Ordinary multiple regression and its generalized form (GLM) are very popular and are often used for modeling species distributions. Other methods include neural networks, ordination and classification methods, Bayesian models, locally weighted approaches (e.g. GAM), environmental envelopes or even combinations of these models. The selection of an appropriate method should not depend solely on statistical considerations. Some models are better suited to reflect theoretical findings on the shape and nature of the species’ response (or realized niche). Conceptual considerations include e.g. the trade-off between optimizing accuracy versus optimizing generality. In the field of static distribution modeling, the latter is mostly related to selecting appropriate predictor variables and to designing an appropriate procedure for model selection. New methods, including threshold-independent measures (e.g. receiver operating characteristic (ROC)-plots) and resampling techniques (e.g. bootstrap, cross-validation) have been introduced in ecology for testing the accuracy of predictive models. The choice of an evaluation measure should be driven primarily by the goals of the study. This may possibly lead to the attribution of different weights to the various types of prediction errors (e.g. omission, commission or confusion). Testing the model in a wider range of situations (in space and time) will permit one to define the range of applications for which the model predictions are suitable. In turn, the qualification of the model depends primarily on the goals of the study that define the qualification criteria and on the usability of the model, rather than on statistics alone.
For many applications the continuous prediction afforded by species distribution modeling must be converted to a map of presence or absence, so a threshold probability indicative of species presence must be fixed. Because of the bias in probability outputs due to frequency of presences (prevalence), a fixed threshold value, such as 0.5, does not usually correspond to the threshold above which the species is more likely to be present. In this paper four threshold criteria are compared for a wide range of sample sizes and prevalences, modeling a virtual species in order to avoid the omnipresent error sources that the use of real species data implies. In general, sensitivity–specificity difference minimizer and sensitivity–specificity sum maximizer criteria produced the most accurate predictions. The widely-used 0.5 fixed threshold and Kappa-maximizer criteria are the worst ones in almost all situations. Nevertheless, whatever the criteria used, the threshold value chosen and the research goals that determined its choice must be stated.
Making the necessary linkage between restoring biodiversity and supporting human livelihoods in Madagascar.
Three complexes constructed with 2,2′-biphenyldicarboxylic acid, multidentate nitrogen donors, and metal salts, {[Cd(2,2′-dpdc)(tppp)(H2O)]2 · 2H2O} n (1), {[Pb(2,2′-dpdc)(pyphen)]2} n (2), and {[Pb(2,2′-dpdc)(dppz)]} n (3) (H2dpdc = 2,2′-diphenyldicarboxylic acid; tppp = 4-(1H-1,3,7,8-tetraazacyclopenta[l]phenanthren-2-yl)phenol; pyphen = pyrazino[2,3-f]-[1,10]phenanthroline; and dppz = dipyrido[3,2-a:2′,3′-c]phenazine), are synthesized under hydrothermal conditions. These complexes are characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA, and photoluminescence. In 1, two 2,2′-dpdc ions bridge two Cd(II) ions to form an isolated cluster with Cd ··· Cd distance of 5.023(4) Å. These clusters are further linked by intermolecular hydrogen bonds, yielding a 2-D supramolecular structure. Complex 2 contains two crystallographically independent Pb(II) ions in the asymmetric unit. Pb1 ions are bridged by 2,2′-dpdc anions to form a chain along the x-axis. Two Pb2 ions are coordinated by two 2,2′-dpdc anions and two pyphen ligands to form a cluster. These clusters are linked by π–π interactions to yield a 1-D supramolecular chain along the y-axis. In 3, neighboring Pb(II) atoms are bridged by 2,2′-dpdc anions to form a 1-D chain structure. Further, the chains are linked into a 3-D supramolecular network through aromatic π–π interactions.
Norway spruce (Picea abies [L.] Karst.) has a pronounced ability to create different crown types embracing strongly hypotonic, epi-hypotonic, strongly amphitonic types as well as respective intermediate ones. Data of Holzer and Schultze (1987) were reanalyzed in order to identify major environmental components that may shape ecotypes and contribute to Gruber's (1989) hypothesis that phenotypic plasticity is different among different crown types. Environmental variables and crown types were assessed by Principal Components Analysis. The first principal component explained 74% of the variation that was mainly loaded by different temperature variables and altitude while the second principal component explained additional 23% mainly loaded by precipitation variables. Orientation had a statistically significant but small effect. Covariance analysis demonstrated that age had modified crown type in a way that more hypotonic types were phenotypically more variable. Overlaps between crown-type distributions were evaluated by Schoener's Index, which may range from ‘zero’ (no ecotypic overlap) to ‘one’ (complete ecotypic overlap). In the present paper this index resulted in pairwise values varying from 0.21 to 0.86. The ecotypic overlap matrix was symmetric, i.e. ecotypic pairs increased gradually with stepwise crown-type graduation. We discussed the adaptation strategy of Norway spruce based on our results and propose that adaptation in this species regarding crown architecture is mainly caused by adaptive differentiation in higher altitudes while in lower elevations phenotypic plasticity is the dominating factor.
The baobab tree, with more than 300 uses and commercial value in EU and United States, has been identified as one of the most important trees to be conserved and domesticated in Africa. A decline in baobab populations because of changes in climate could have a negative effect on African livelihoods. Therefore, it is important to study the potential future distribution of this species and determine strategies for conservation. We used Maxent, 480 geo-referenced records, present and future climatic and soil layers. Different general circulation models and scenarios were selected. Models were simulated for (i) All records, (ii) East Africa and (iii) West Africa species records. For each combination, the proportion of the present habitat that might remain suitable in the future was determined. These habitat proportions were compared with the Protected Areas in Africa. Although potential future distributions were different depending on model, scenario and records used, in all cases only a percentage of the present distribution was predicted to remain suitable in the future. Some countries were found to have no suitable habitat in the future. Recommendations for different conservation strategies include in situ conservation in Protected Areas; ex situ conservation in seed banks; and conservation through 'sustainable utilization'.
Reintroduction programs are a high-risk conservation strategy for restoring populations of endangered species. The success of these programs often depends on the ability to identify suitable habitat within the species’ former range. Bioclimatic analysis offers an empirical, explicit, robust, and repeatable method to analyze large areas rapidly using a small number of locality records, and in turn predicting (and/or reconstructing) its potential distribution limits. This approach therefore can estimate the broad limits of the distribution of a taxon, using data that may be inadequate for standard forms of statistical analysis. We illustrate the potential value of bioclimatic modeling for reintroduction biology using a case study of the highly endangered Helmeted Honeyeater (Lichenostomus melanops cassidix) from Victoria, southeastern Australia. The results of our analyses assisted us to both predict the former range limits of the Helmeted Honeyeater and determine the broad limits of those areas that may contain potentially suitable sites for future reintroduction programs for the subspecies. The analysis predicted that the range of the Helmeted Honeyeater extends from the Yarra River district east of Melbourne, south to the Western Port Bay and east as far as the Morwell area of Victoria. The climatic characteristics of habitat occupied by the extant population of the Helmeted Honeyeater were found to be unique within its predicted range. We recommend that reintroduction efforts therefore be concentrated within this small area, as has occurred to date.
1. Conservation of declining migratory species is a challenging task, as the factors that may have determined their past distribution may not determine their current and future distribution. Saiga antelope Saiga tatarica populations have massively declined due to poaching. The species is now beginning to recover in Kazakhstan and protected areas are being implemented. Using 25 years of aerial monitoring data, we identified changes in the spring distribution and predicted densities of saiga to prioritize areas for protection under scenarios of climate change together with changes in disturbance and population size. Conserving the spring distribution is critical as spring calving aggregations are of particular importance to population viability.
Species distribution models have been widely used to predict species distributions for various purposes, including conservation planning, and climate change impact assessment. The success of these applications relies heavily on the accuracy of the models. Various measures have been proposed to assess the accuracy of the models. Rigorous statistical analysis should be incorporated in model accuracy assessment. However, since relevant information about the statistical properties of accuracy measures is scattered across various disciplines, ecologists find it difficult to select the most appropriate ones for their research. In this paper, we review accuracy measures that are currently used in species distribution modelling (SDM), and introduce additional metrics that have potential applications in SDM. For the commonly used measures (which are also intensively studied by statisticians), including overall accuracy, sensitivity, specificity, kappa, and area and partial area under the ROC curves, promising methods to construct confidence intervals and statistically compare the accuracy between two models are given. For other accuracy measures, methods to estimate standard errors are given, which can be used to construct approximate confidence intervals. We also suggest that as general tools, computer-intensive methods, especially bootstrap and randomization methods can be used in constructing confidence intervals and statistical tests if suitable analytic methods cannot be found. Usually, these computer-intensive methods provide robust results.
MaxEnt is a program for modelling species distributions from presence-only species records. This paper is written for ecologists and describes the MaxEnt model from a statistical perspective, making explicit links between the structure of the model, decisions required in producing a modelled distribution, and knowledge about the species and the data that might affect those decisions. To begin we discuss the characteristics of presence-only data, highlighting implications for modelling distributions. We particularly focus on the problems of sample bias and lack of information on species prevalence. The keystone of the paper is a new statistical explanation of MaxEnt which shows that the model minimizes the relative entropy between two probability densities (one estimated from the presence data and one, from the landscape) defined in covariate space. For many users, this viewpoint is likely to be a more accessible way to understand the model than previous ones that rely on machine learning concepts. We then step through a detailed explanation of MaxEnt describing key components (e.g. covariates and features, and definition of the landscape extent), the mechanics of model fitting (e.g. feature selection, constraints and regularization) and outputs. Using case studies for a Banksia species native to south-west Australia and a riverine fish, we fit models and interpret them, exploring why certain choices affect the result and what this means. The fish example illustrates use of the model with vector data for linear river segments rather than raster (gridded) data. Appropriate treatments for survey bias, unprojected data, locally restricted species, and predicting to environments outside the range of the training data are demonstrated, and new capabilities discussed. Online appendices include additional details of the model and the mathematical links between previous explanations and this one, example code and data, and further information on the case studies.
Habitat management is essential for safeguarding important flora and fauna. Further, habitat connectivity is a crucial component
for maintaining biodiversity given that it is known to have implications for species persistence. However, damage to habitat
due to natural and human induced hazards can alter spatial relationships between habitats, potentially impacting biodiversity.
Therefore, the susceptibility of spatial relationships to patch loss and associated connectivity degradation is obviously
an important factor in maintaining existing or planned habitat networks. Identifying patches vital to connectivity is critical
both for effectively prioritizing protection (e.g., enhancing habitat connectivity) and establishing disaster mitigation measures
(e.g., stemming the spread of habitat loss). This paper presents a methodology for characterizing connectivity associated
with habitat networks. Methods for evaluating habitat network connectivity change are formalized. Examples are presented to
facilitate analysis of connectivity in the management of biodiversity.
Establishing cause–effect relationships for deforestation at various scales has proven difficult even when rates of deforestation appear well documented. There is a need for better explanatory models, which also provide insight into the process of deforestation. We propose a novel hierarchical modeling specification incorporating spatial association. The hierarchical aspect allows us to accommodate misalignment between the land-use (response) data layer and explanatory data layers. Spatial structure seems appropriate due to the inherently spatial nature of land use and data layers explaining land use. Typically, there will be missing values or holes in the response data. To accommodate this we propose an imputation strategy. We apply our modeling approach to develop a novel deforestation model for the eastern wet forested zone of Madagascar, a global rain forest “hot spot”. Using five data layers created for this region, we fit a suitable spatial hierarchical model. Though fitting such models is computationally much more demanding than fitting more standard models, we show that the resulting interpretation is much richer. Also, we employ a model choice criterion to argue that our fully Bayesian model performs better than simpler ones. To the best of our knowledge, this is the first work that applies hierarchical Bayesian modeling techniques to study deforestation processes. We conclude with a discussion of our findings and an indication of the broader ecological applicability of our modeling style.
The availability of detailed environmental data, together with inexpensive and powerful computers, has fueled a rapid increase in predictive modeling of species environmental requirements and geographic distributions. For some species, detailed presence/absence occurrence data are available, allowing the use of a variety of standard statistical techniques. However, absence data are not available for most species. In this paper, we introduce the use of the maximum entropy method (Maxent) for modeling species geographic distributions with presence-only data. Maxent is a general-purpose machine learning method with a simple and precise mathematical formulation, and it has a number of aspects that make it well-suited for species distribution modeling. In order to investigate the efficacy of the method, here we perform a continental-scale case study using two Neotropical mammals: a lowland species of sloth, Bradypus variegatus, and a small montane murid rodent, Microryzomys minutus. We compared Maxent predictions with those of a commonly used presence-only modeling method, the Genetic Algorithm for Rule-Set Prediction (GARP). We made predictions on 10 random subsets of the occurrence records for both species, and then used the remaining localities for testing. Both algorithms provided reasonable estimates of the species’ range, far superior to the shaded outline maps available in field guides. All models were significantly better than random in both binomial tests of omission and receiver operating characteristic (ROC) analyses. The area under the ROC curve (AUC) was almost always higher for Maxent, indicating better discrimination of suitable versus unsuitable areas for the species. The Maxent modeling approach can be used in its present form for many applications with presence-only datasets, and merits further research and development.
In this article we discuss our experience designing and implementing a statistical computing language. In developing this new language, we sought to combine what we felt were useful features from two existing computer languages. We feel that the new language provides advantages in the areas of portability, computational efficiency, memory management, and scoping.
Networks of sites of high importance for conservation of biological diversity are a cornerstone of current conservation strategies but are fixed in space and time. As climate change progresses, substantial shifts in species’ ranges may transform the ecological community that can be supported at a given site. Thus, some species in an existing network may not be protected in the future or may be protected only if they can move to sites that in future provide suitable conditions. We developed an approach to determine appropriate climate-change adaptation strategies for individual sites within a network that was based on projections of future changes in the relative proportions of emigrants (species for which a site becomes climatically unsuitable), colonists (species for which a site becomes climatically suitable), and persistent species (species able to remain within a site despite the climatic change). Our approach also identifies key regions where additions to a network could enhance its future effectiveness. Using the sub-Saharan African Important Bird Area (IBA) network as a case study, we found that appropriate conservation strategies for individual sites varied widely across sub-Saharan Africa, and key regions where new sites could help increase network robustness varied in space and time. Although these results highlight the potential difficulties within any planning framework that seeks to address climate-change adaptation needs, they demonstrate that such planning frameworks are necessary, if current conservation strategies are to be adapted effectively, and feasible, if applied judiciously.
The ranges of plants and animals are moving in response to recent changes in climate. As temperatures rise, ecosystems with 'nowhere to go', such as mountains, are considered to be more threatened. However, species survival may depend as much on keeping pace with moving climates as the climate's ultimate persistence. Here we present a new index of the velocity of temperature change (km yr(-1)), derived from spatial gradients ( degrees C km(-1)) and multimodel ensemble forecasts of rates of temperature increase ( degrees C yr(-1)) in the twenty-first century. This index represents the instantaneous local velocity along Earth's surface needed to maintain constant temperatures, and has a global mean of 0.42 km yr(-1) (A1B emission scenario). Owing to topographic effects, the velocity of temperature change is lowest in mountainous biomes such as tropical and subtropical coniferous forests (0.08 km yr(-1)), temperate coniferous forest, and montane grasslands. Velocities are highest in flooded grasslands (1.26 km yr(-1)), mangroves and deserts. High velocities suggest that the climates of only 8% of global protected areas have residence times exceeding 100 years. Small protected areas exacerbate the problem in Mediterranean-type and temperate coniferous forest biomes. Large protected areas may mitigate the problem in desert biomes. These results indicate management strategies for minimizing biodiversity loss from climate change. Montane landscapes may effectively shelter many species into the next century. Elsewhere, reduced emissions, a much expanded network of protected areas, or efforts to increase species movement may be necessary.
Separated from the mainland of Africa for 160 million years, Madagascar has evolved an incredible wealth of biodiversity, with thousands of species that can be found nowhere else on earth. For instance, of its estimated 12,000 plant species, nearly 10,000 are unique to Madagascar. Malagasy animals are just as spectacular, from its almost forty currently recognized species of lemursâa primate group found only hereâto the numerous species of tiny dwarf chameleons. With astounding frequency scientists discover a previously unknown species in Madagascarâand at almost the same rate another natural area of habitat is degraded or destroyed, a combination that recently led conservation organizations to name Madagascar one of the most important and threatened conservation priorities on the planet. The Natural History of Madagascar provides the most comprehensive, up-to-date synthesis available of this island nation's priceless biological treasures. Contributions by nearly three hundred world-renowned experts cover the history of scientific exploration in Madagascar, its geology and soils, climate, forest ecology, human ecology, marine and coastal ecosystems, plants, invertebrates, fishes, amphibians, reptiles, birds, and mammals. Detailed discussions of conservation efforts in Madagascar highlight several successful park reserve programs that could serve as models for other areas. Beautifully illustrated throughout, the book includes over one hundred color illustrations, with fifty color photos by nature photographer Harald Schütz, as well as more than three hundred black-and-white photographs and line drawings. The Natural History of Madagascar will be the invaluable reference for anyone interested in the Malagasy environment, from biologists and conservationists to policymakers and ecotourists. âFor those who are serious about getting to know this fascinating island, there is no better resource.ââTim Flannery, Nature âA magnificent overview of one of the strangest and most glorious chunks of the planet.ââAdrian Barnett, New Scientist âA scientific milestone and by far the largest synthesis of tropical biology research ever.ââScience
Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.
Global warming is a key threat to biodiversity, but few researchers have assessed the magnitude of this threat at the global scale. We used major vegetation types (biomes) as proxies for natural habitats and, based on projected future biome distributions under doubled-CO2 climates, calculated changes in habitat areas and associated extinctions of endemic plant and vertebrate species in biodiversity hotspots. Because of numerous uncertainties in this approach, we undertook a sensitivity analysis of multiple factors that included (1) two global vegetation models, (2) different numbers of biome classes in our biome classification schemes, (3) different assumptions about whether species distributions were biome specific or not, and (4) different migration capabilities. Extinctions were calculated using both species-area and endemic-area relationships. In addition, average required migration rates were calculated for each hotspot assuming a doubled-CO2 climate in 100 years. Projected percent extinctions ranged from <1 to 43% of the endemic biota (average 11.6%), with biome specificity having the greatest influence on the estimates, followed by the global vegetation model and then by migration and biome classification assumptions. Bootstrap comparisons indicated that effects on hotpots as a group were not significantly different from effects on random same-biome collections of grid cells with respect to biome change or migration rates; in some scenarios, however, botspots exhibited relatively high biome change and low migration rates. Especially vulnerable hotspots were the Cape Floristic Region, Caribbean, Indo-Burma, Mediterranean Basin, Southwest Australia, and Tropical Andes, where plant extinctions per hotspot sometimes exceeded 2000 species. Under the assumption that projected habitat changes were attained in 100 years, estimated global-warming-induced rates of species extinctions in tropical hotspots in some cases exceeded those due to deforestation, supporting suggestions that global warming is one of the most serious threats to the planet's biodiversity.