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Predicting the impacts of human population growth on forest mammals in the highlands of southwestern Ethiopia
Abstract
Projections of human population growth for 2050 indicate that Africa is expected to steadily increase its rural population, raising questions on how to best accommodate people while minimizing impacts on biodiversity. We explored the outcomes of scenarios of rural population growth mediated by housing development. We designed our scenarios based on (i) patterns of housing development (i.e., housing densification versus expansion), (ii) level of human population growth, and (iii) forest protection. Using camera traps, we surveyed mammals in the moist Afromontane forests of southwestern Ethiopia. We modelled mammals' responses to current and alternative housing development trajectories, using generalized additive mixed models. Our results suggest that (i) rural population growth is likely to negatively influence several mammal species, including a threatened predator (the leopard) as well as common crop raiding species such as baboons; (ii) negative impacts of population growth are likely to be exacerbated if new housing encroaches the forest (i.e., expansion), and likely to be less detrimental if houses are built within the existing human footprint (i.e., densification); and (iii) effects of human population growth can be modified by land-use decisions unrelated to biodiversity conservation, such as protection of economically important forest cover (native coffee forest in our study area). The location, extent and magnitude of housing development in southwestern Ethiopia can limit the ability of several mammal species to persist in the landscape. Our findings suggest that incorporating the ecological effects of housing development into landscape planning is fundamental to align conservation goals with development plans.
... In these landscapes, there is a strong overlap of humans and wildlife, making this region particularly interesting to examine interactions between wildlife and people. This region is within a hotspot of biodiversity, holding large complexes of moist evergreen Afromontane forest that support a diverse community of mammals, including toppredators (leopard and spotted hyena) (Rodrigues et al., 2021). Arabica coffee occurs naturally in these forests and is also traditionally grown and produced by local communities as a cash crop. ...
... It comprises an area of about 3800 km 2 (Fig. 2b) and elevation ranges between 1300 and 3000 m above sea level. This highland region holds remnants of moist evergreen Afromontane forest, rich in biodiversity (Buechley et al., 2015;Etana et al., 2021;Mertens et al., 2018;Rodrigues et al., 2018;Shumi et al., 2019b), with more than 30 mammal species recorded in the region (Rodrigues et al., 2021). The natural occurrence of Arabica coffee contributes to the high biodiversity value of these forests. ...
... The mammal community was assessed in four kebeles (i.e., the smallest administrative unit; Fig. 2b) within the study area and located in two districts or woredas. The kebele area varied between 2345 and 5200 ha and population density between 66 and 137 people/km 2 (Rodrigues et al., 2021). Current forest cover in the study kebeles varies between 33 and 88%. ...
... The forest dataset on birds was analysed using detrended correspondence analysis, canonical correspondence analysis and generalized linear mixed models ; farmland data are unpublished to date. Camera traps were used to survey mammals at the forest edge (25 sites across four kebeles, Rodrigues et al. 2019) and in the forest interior (95 sites in four kebeles, between 14 and 31 camera sites per kebele, Rodrigues et al. 2021). More than 500,000 photos were classified using ExiPRO TM software. ...
... For mammals, 32 species were recorded. These included the leopard (Pantera pardus) and hyena (Crocuta crocuta) as top predators, as well as the baboon (Papio anubis) and bushpig (Potamochoerus larvatus) as potentially crop raiding species (Rodrigues et al. 2021). Within the forest, the recording rate of the leopard increased with distance from the forest edge ( Figure 2, Table S1a and S1b), whereas potentially cropraiding species such as the baboon showed no response to distance from the edge (Tables S1a, S1b; Fig. S1). ...
... Notwithstanding the usefulness of this socialecological approach, we are acutely aware that it still generated only a partial understanding of the studied system. For example, we did not specifically deal with human population growth in this paper, although it is a critical driver of both food insecurity and biodiversity loss (and we address it in more recent work; see Rodrigues 2020; Rodrigues et al. 2021). Similarly, the issues of climate change and declining soil fertility were frequently raised as important by local people, but our work only marginally addressed these topics. ...
We studied food security and biodiversity conservation from a social-ecological perspective in southwestern Ethiopia. Specialist tree, bird, and mammal species required large, undisturbed forest, supporting the notion of ‘land sparing’ for conservation. However, our findings also suggest that forest areas should be embedded within a multifunctional landscape matrix (i.e. ‘land sharing’), because farmland also supported many species and ecosystem services and was the basis of diversified livelihoods. Diversified livelihoods improved smallholder food security, while lack of access to capital assets and crop raiding by wild forest animals negatively influenced food security. Food and biodiversity governance lacked coordination and was strongly hierarchical, with relatively few stakeholders being highly powerful. Our study shows that issues of livelihoods, access to resources, governance and equity are central when resolving challenges around food security and biodiversity. A multi-facetted, social-ecological approach is better able to capture such complexity than the conventional, two-dimensional land sparing versus sharing framework.
... About 95% of the ranges of carnivore species occur outside protected areas in a human-dominated landscape [27]. Thus, understanding the carnivore species that coexist with humans is important for both carnivore conservation and the local people's livelihood [6,28]. As a result, for carnivore conservation to be successful, both protected areas and the human-dominated landscape must be addressed [10]. ...
... This might be due to their more adaptable nature to different land-uses, diverse foraging behavior (fruits, meat), and high tolerance level for human disturbances [2,11,32]. For the Felidae, it could be wild and domestic prey availability, high vegetation cover, and access to water [28]. The family's Hyaenidae and Mustelidae have low species richness, which could be attributed to anthropogenic pressure in the area. ...
Anthropogenic land-use changes pose signifcant threats to the diversity and occurrence of wildlife species around the
world. We investigated how land-use and environmental factors afect the richness and occurrence of carnivore species
in the Faragosa-Fura Landscape of the Southern Rift Valley of Ethiopia. We used the line transect method to collect data,
combining three complementary feld survey techniques: sign survey, camera trapping, and opportunistic sighting surveys. We confrmed the presence of 12 carnivore species belonging to six families, including the vulnerable Felidae species
Panthera pardus. More species were found in the family’s Felidae and Herpestidae, while Hyaenidae and Mustelidae were
composed of a single species each. The two large-sized species identifed were Panthera pardus and Crocuta crocuta. The
species richness was the highest in wetlands, while it was the lowest in the settlement. The occurrence of most carnivores
was negatively associated with agricultural land and settlements, while they were positively associated with wetlands
and altitude. Genetta genetta had the highest occurrence, while Panthera pardus had the lowest in the area. We concluded
that of the studied habitats, wetlands are the most important, and anthropogenic land-uses have a negative impact on
species richness. Our fndings provide valuable baseline data for stakeholders making critical conservation decisions as
well as researchers conducting related ecological studies in a human-dominated landscape. Based on our fndings, we
propose a basic approach for integrating land management and wildlife conservation.
... Although the in-migration of land-seeking smallholders will increase the demand for cropland, the densification of settlement sites could reduce the further sprawl of human settlement into intact forest areas and thus reduce negative impacts on biodiversity (Rodrigues et al. 2021). ...
Forest decline and degradation are particularly high in the tropics and pose a risk to those who depend on forest resources. The in-migration of smallholders to forest frontiers can fuel transitions of livelihoods and land and resource use. However, the conditions under which in-migration contributes to such transitions remain poorly understood. With this study, we aim to investigate the influence of in-migration, together with other non-demographic factors, on the livelihoods of local and migrant communities. As a case study, we chose the Guraferda district, a hotspot of rural in-migration and forest loss in southwest Ethiopia, where the forest-based local population experienced a rapid transition to agriculture-based livelihoods. We used 224 household surveys in three different kebeles (smallest administrative unit in Ethiopia) and applied descriptive and analytical statistics to understand how and why the forest activities of local and migrant groups have changed since a major resettlement program was launched in 2003. The findings were contextualized by local expert knowledge to assess forest loss and the role of in-migration in livelihood transitions and deforestation. Forest cover in Guraferda declined partially because of the in-migration of smallholders from agricultural-based systems, and insecure land tenure, but also considerably because of the expansion of commercial agriculture. With the decline in forest, the local population adopted migrants’ agricultural practices, a trend further encouraged by agricultural policies and barriers to participation in forest management for locals. Our study challenges simplified assumptions in in-migration–deforestation debates by showing that governmental policies, land tenure, and natural-resource access are mediating the impact of migration on livelihood transitions and deforestation. We conclude that securing land tenure and equal access to natural resources for frontier residents and promoting a mix of agricultural and forest livelihood activities can reduce adverse impacts in in-migration areas.
... In the study area, the distance from the human population settlements had less of an influence in predicting the current habitat suitability model of Djaffa Mountains Guereza. A pronounced negative influence of rural human population growth on several mammal species was indicated in the highlands of southwestern Ethiopia (Rodrigues et al., 2021). A variable distance to roads had no relationship with the Djaffa Mountains Guereza occurrence. ...
Understanding the impacts of climate change, landscape composition, topographic attributes, and anthropogenic disturbance on wildlife distribution is critical to selecting prior conservation areas and to executing successful management plans. Habitat suitability mapping aims to predict species' ecological niches and ranges using these factors as predictors. There has been no study of the potentially suitable habitat for the data-deficient Djaffa Mountains Guereza and the factors affecting its distribution in the Ahmar Mountains. The objective of this study was to predict the habitat suitability and distribution models of Djaffa Mountains Guereza in eastern Ethiopian highland under different climate change scenarios using maximum entropy (MaxEnt) model. We used 47 occurrence datasets assembled between 2020 and 2021 and 10 ecological predictor variables processed in geographical information systems and R software. We found that 133,604.52 ha (1.77%) of the 753, 0749.39 ha study area is suitable habitat for the Djaffa Mountains Guereza, of which 18,326.12 (13.33%) ha were highly suitable, whereas the remaining area was moderately suitable. Our models also showed that precipitation of the wettest quarter had the highest contribution to predicting the habitat suitability (65.90%), followed by land cover (17.40%). Habitat suitability was directly related to precipitation seasonality and the precipitation of the wettest quarter, while it is indirectly related to temperature seasonality and the temperature mean diurnal range. The models showed the overall gain in the suitable habitat of Djaffa Mountains Guereza under all future climate scenarios, however, the projected habitat distribution show fragmentation. Our habitat suitability and distribution models provide critical information for the conservation and management of Djaffa Mountains Guereza by recommending stocking of the fragmented forests, assessment of conservation challenges, and mitigations of climate change. A comprehensive population assessment throughout their restricted distribution is also crucial to understand conservation status and population size.
... Southwestern Ethiopia is part of a globally recognized biodiversity hotspot (Mittermeier et al. 2011); it is the origin of coffee (Coffea arabica), and the landscape is a mosaic of extensive forested areas (approximately 50%) and mixed farmland, densely inhabited by subsistence farmers. Ecologically, we examined the distribution patterns of trees, birds and mammals in relation to historical and current human land use (Rodrigues et al. , 2021Shumi et al. 2018Shumi et al. , 2019. In terms of social issues, we studied the governance structures and processes influencing food security and biodiversity (Jiren et al. 2018a;Bergsten et al. 2019), as well as household-level livelihood strategies and food security (Manlosa et al. 2019a(Manlosa et al. , 2019b. ...
A leverage points perspective recognises different levels of systemic depth, ranging from the relatively shallow levels of parameters and feedbacks to the deeper levels of system design and intent. Analysing a given social-ecological system for its characteristics across these four levels of systemic depth provides a useful diagnostic to better understand sustainability problems, and can complement other types of cause-and-effect systems modelling. Moreover, the structured comparison of multiple systems can highlight whether sustainability challenges in different systems have a similar origin (e.g. similar feedbacks or similar design). We used a leverage points perspective to systematically compare findings from three in-depth social-ecological case studies, which investigated rural landscapes in southeastern Australia, central Romania, and southwestern Ethiopia. Inductive coding of key findings documented in over 60 empirical publications was used to generate synthesis statements of key findings in the three case studies. Despite major socioeconomic and ecological differences, many synthesis statements applied to all three case studies. Major sustainability problems occurred at the design and intent levels. For example, at the intent level, all three rural landscapes were driven by goals and paradigms that mirrored a productivist green revolution discourse. Our paper thus highlights that there are underlying challenges for rural sustainability across the world, which appear to apply similarly across strongly contrasting socioeconomic contexts. Sustainability interventions should be mindful of such deep similarities in system characteristics. We conclude that a leverage points perspective could be used to compare many other types of social-ecological systems around the world.
... Forests once covered 35% of the country's area, but this proportion declined to about 2.5% (EFAP, 1994). The impact of increasing human population has become the main driver of progressive contractions of natural habitats (Rodrigues et al., 2021;Shumi et al., 2019;Tesfaye et al., 2002). Although part of the Harenna forest lies in the Bale Mts. ...
The Ethiopian highlands represent the largest part of the Eastern Afromontane Biodiversity Hotspot (EAMBH). Their fauna and flora are largely unique. Particularly, Afroalpine habitats on isolated mountains are known to harbour a large number of highly specialized endemic species. In contrast to intensively studied Afroalpine ecosystems, the forests in southern and southwestern parts of the Ethiopian highlands remain neglected in terms of biodiversity research, even though they represent the only remaining natural large-scale forests in this part of EAMBH. Here, we performed an integrative taxonomic revision (combining multi-locus phylogenetic analysis with classical and geometric morphometrics) and analysis of the evolutionary history of ancient lineages of the genus Mus, with a special focus on the taxon discovered in moist Ethiopian forests. We unequivocally showed that this taxon forms a very distinct gene pool separated from other taxa by the mid-Pliocene, substantially differentiated from both sympatric and sister species by external and cranial morphology. None of the available type specimens (including synonym types) can be unambiguously classified to this taxon according to both skull and body form. Therefore, we describe it as a new mammal species, narrowly endemic to two most humid forests in southern (Harenna) and southwestern (Chingawa) part of the Ethiopian highlands. The description of such paleo-endemic taxa will add incentives to embark on urgent conservation action for formal protection of these unique forests within the EAMBH.
... These wild animals began to steal fruit from home gardens (Ango et al., 2017). The wild animals prefer forests near human residents, and therefore the plantation trees favor them to be closer to home gardens (Rodrigues et al., 2021). The Bush pig (Potamochoerus larvatus) and the Warthog (Phacochoerus africanus) were also other common crop-raiding species (Ango et al., 2017;Dorresteijn et al., 2017). ...
The perceived value of Forest Ecosystem Services (FES) varies according to cultural, socioeconomic , and environmental conditions. A scientific understanding of how these determinants interact and determine the perceived values of the local community of FES is beneficial for the planning and management of forest resources. This study aimed at contributing to this knowledge gap by examining the impacts of socio-environmental variables for the perceived use-value variation of FES. The sample sites were selected using a stratified sampling method. The data were collected through a social survey with face-to-face interviews and focus group discussions. The results were analyzed using the general linear model, Principal Component Analysis (PCA), Confirmatory Factor Analysis (CFA), Mann-Whitney U, and the Kruskal-Wallis test (χ2). For the general assessment, the respondents were provided with a list of 26 FES as stipulated in the Millennium Ecosystem Assessment Framework. The results illustrated that the Afromontane moist forests offer multiple Ecosystem Services (ES) that could provide social, economic, and physical well-being to residents. The local community prioritized provisioning and regulatory over cultural and supporting ES. The χ2 result showed that only the length of stay and age of the respondents significantly determined variation in the perceived value of FES. The CFA score suggests that a strong correlation was found between cultural, regulatory, and supportive ES. Overall, the respondents mentioned freshwater, climate regulation, and air quality regulation as the most important FES. In summary, the study helps to highlight the impacts of socio-environmental variables on the perceived value of FES and the need to integrate local values into the policy-making process.
... Natural forest was used as a reference level for habitat categorical variable and camera station was included as a random factor. their habitats (Tesfaye et al., 2013(Tesfaye et al., , 2021Rodrigues et al., 2021). ...
Ethiopian shade coffee plantations are well documented to be bird-friendly and act as refuges for disappearing tree species. The extent to which these plantations support mammal conservation, as well as mammal sensitivity to coffee intensification, remain little studied. We studied the distribution and diversity of mammals under three
coffee management systems of differing intensities (i.e., semi-forest, semi-plantation, and plantation) and in nearby natural forests in Belete-Gera Forest Priority Area, southwestern Ethiopia. We detected mammals using 30 infrared camera traps at 90 stations for a total of 4142 camera days. We used the Shannon-Wiener diversity index for diversity analysis, generalized linear mixed model for comparison of independent detection, and non-metric
multidimensional scaling to show the mammalian community composition. We recorded 8815 digital videos and a total of 23 mammal species. The overall species richness, diversity, and detection of mammals did not differ between the two traditional shade coffee management systems and the natural forest but was lower in the plantation coffee system. The mammal community composition also shows variation in resilience to coffee
management intensity, with primates appearing to be generally more tolerant to management intensification. We ultimately show that traditionally managed Ethiopian shade coffee farms shelter diverse mammal communities, comparable to those in nearby natural forests. Therefore, supporting traditional coffee management practices and certifying them as mammal-friendly should be implemented as strategies for the conservation of mammals, as natural forests continue to decline in Ethiopia.
Camera traps have been used increasingly as a research tool to monitor wildlife globally, and have become more advanced, thereby improving their performance and lowering costs. Their use has allowed researchers to study a range of species, including rare and elusive species, particularly in remote areas, in a non-invasive, reliable and cost-effective way. In this review, we sought to document the camera trapping research on terrestrial wildlife conducted in Africa, identifying countries and habitat types of focus, and how these camera trap research trends in Africa could be improved in the future. Through a systematic literature search, we found 408 peer-reviewed publications using camera traps to study terrestrial wildlife in Africa, with the first being in 2005 and up to 2021. Although camera trap studies were conducted in 38 African countries, most were in South Africa (28.9%). Most studies assessed the occupancy of species (41.4%). The studies covered a range of taxa, with mammals being the most popular. The majority of research focussed on large carnivores (24.8%), with a particular focus on leopards (Panthera pardus) (60 studies). Most studies (43.9%) focused on a single species, with forests (174 studies, 42.6%) and savannah/bushveld (145 studies, 35.5%) being the habitat type of focus. There was also a strong preference for camera trap studies to be conducted in protected areas (68.9%). The camera trap methods used varied considerably between studies, which included: the number of camera trap stations, survey length, trap effort, camera trap make and model, camera trap flash type, interval delay, camera multishot, height of camera trap placement, camera trap layout method and whether the camera trap was baited. These variations are expected because of the difference in research goals posed by each study. However, studies with similar objectives and/or focus still display a clear lack of standardisation (studies do not conform to a specific standard), which could negatively impact the results obtained, as inappropriate camera trap protocols could affect the detectability of certain species. Future camera trap studies will hopefully extend to countries and taxa that have received little attention, with further research informing appropriate conservation strategies that could reduce the threats to biodiversity.
Sea level rise (SLR) due to climate change is affecting the coastline, causing shoreline changes, the degradation of mangrove forests, and the destruction of coastal resources. This is the cause of a huge amount of mangrove degradation in many parts of the Ganges–Brahmaputra–Meghna delta. A total of 90% of people have been forced to migrate from the island due to extreme weather conditions. In this study, remote sensing (RS) and geographic information system (GIS) techniques were used for LULC change and shoreline shift analyses of Ghoramara Island. LULC classification was carried out using thirty years of Landsat datasets with intervals of ten years (1990 and 2000) and intervals of five years (2005, 2010, 2015, and 2020). The classification was conducted using a supervised classification method. The field survey data were used to validate the classification results. The total area was reduced from 608 ha (in 1990) to 375 ha (in 2020) due to the extreme weather conditions. Around 39% of the land area was found to be degraded due to shoreline changes. The LULC classes of built-up area, agricultural land, water bodies, and vegetation were found to have lost around 62.345 ha, 63.328 ha, 0.836 ha, and 113.241 ha, respectively, from the year 1990–2020. It was observed that the shoreline shifted towards the north-east, north-west, and southern directions in the last thirty years. This study identified the land use changes due to shoreline shifting and proposed the appropriate to achieve the sustainable development of Ghoramara Island.
We investigated the spatial relations of ecological and social processes to point at how state policies, population density, migration dynamics, topography, and socio-economic values of ‘forest coffee’ together shaped forest cover changes since 1958 in southwest Ethiopia. We used data from aerial photos, Landsat images, digital elevation models, participatory field mapping, interviews, and population censuses. We analyzed population, land cover, and topographic roughness (slope) data at the ‘sub-district’ level, based on a classification of the 30 lowest administrative units of one district into the coffee forest area (n = 17), and highland forest area (n = 13). For state forest sites (n = 6) of the district, we evaluated land cover and slope data. Forest cover declined by 25% between 1973 and 2010, but the changes varied spatially and temporally. Losses of forest cover were significantly higher in highland areas (74%) as compared to coffee areas (14%) and state forest sites (2%), and lower in areas with steeper slopes both in coffee and highland areas. Both in coffee and highland areas, forest cover also declined during 1958–1973. People moved to and converted forests in relatively low population density areas. Altitudinal migration from coffee areas to highland areas contributed to deforestation displacement due to forest maintenance for shade coffee production in coffee areas and forest conversions for annual crop production in highland areas. The most rapid loss of forest cover occurred during 1973–1985, followed by 2001–2010, which overlapped with the implementations of major land and forest policies that created conditions for more deforestation. Our findings highlight how crop ecology and migration have shaped spatial variations of forest cover change across different altitudinal zones whilst development, land, and forest policies and programs have driven the temporal variations of deforestation. Understanding the mechanisms of deforestation and forest maintenance simultaneously and their linkages is necessary for better biodiversity conservation and forest landscape management.
Coastal ecosystems suffer substantially from the worldwide population growth and its increasing land demands. A common approach to investigate anthropogenic disturbance in coastal ecosystems is to compare urbanized areas with unaffected control sites. However, the question remains whether different types of anthropogenic disturbance that are elements of an urbanized area have the same impact on beach ecosystems. By investigating small islands that are utilized for tourism, inhabited by the local population, or remained completely uninhabited, we disentangled different anthropogenic disturbances and analysed their impacts on hermit crabs as indicator species. We observed a negative impact on abundance on tourist islands and a negative impact on body size on local islands. In comparison to the uninhabited reference, both disturbances had an overall negative impact. As both forms of disturbance also impacted the underlying food resource and habitat availability differently, we propose that the findings from our study approach are valid for most obligate beach species in the same system. This demonstrates that in urbanized areas, the coastal ecosystem is not always impacted identically, which emphasizes the importance of considering the particular type of anthropogenic disturbance when planning conservation action in urbanized areas.
Habitat transformations caused by human land-use change are considered major drivers of ongoing biodiversity loss 1–3 , and their impact on biodiversity is expected to increase further this century 4–6 . Here, we used global decadal land-use projections to year 2070 for a range of shared socioeconomic pathways, which are linked to particular representative concentration pathways, to evaluate potential losses in range-wide suitable habitat and extinction risks for approximately 19,400 species of amphibians, birds and mammals. Substantial declines in suitable habitat are identified for species worldwide, with approximately 1,700 species expected to become imperilled due to land-use change alone. National stewardship for species highlights certain South American, Southeast Asian and African countries that are in particular need of proactive conservation planning. These geographically explicit projections and model workflows embedded in the Map of Life infrastructure are provided to facilitate the scrutiny, improvements and future updates needed for an ongoing and readily updated assessment of changing biodiversity. These forward-looking assessments and informatics tools are intended to support national conservation action and policies for addressing climate change and land-use change impacts on biodiversity. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
Households combine capital assets in a process involving human agency and resourcefulness to construct livelihood strategies and generate well-being outcomes. Here, we (1) characterized types of livelihood strategies; (2) determined how different capital assets are associated with different livelihood strategies; and (3) determined how livelihood strategies differed in food security outcomes. We conducted a survey in southwestern Ethiopia and used principal component and cluster analyses. Five types of livelihood strategies, which differed mainly in food and cash crops comprising the strategy, were identified. These were, in order of decreasing food security: ‘three food crops, coffee and khat’, n = 68; ‘three food crops and khat’, n = 59; ‘two food crops, coffee and khat’, n = 78; ‘two food crops and khat’, n = 88; and ‘one food crop, coffee and khat’, n = 44. The livelihood strategy ‘three food crops, coffee and khat’ was associated with a wide range of capital assets, particularly having larger aggregate farm field size and learning from other farmers. A generalized linear model showed that livelihood strategies were significantly associated with food security outcomes. Particularly, a high number of food crops in a strategy was linked with relatively high food security. In this context, diversified livelihood strategies primarily through having a mix of food crops for subsistence, in combination with cash crops for income, are important for food security. This suggests a need to rethink dominant policy narratives, which have a narrow focus on increasing productivity and commercialization as the primary pathway to food security.
Electronic supplementary material
The online version of this article (10.1007/s12571-018-00883-x) contains supplementary material, which is available to authorized users.
Crop foraging or crop raiding concerns wildlife foraging and farmers' reactions and responses to it. To understand crop foraging and its value to wildlife or its implications for humans requires a cross-disciplinary approach that considers the behavior and ecology of wild animals engaging in this behavior; the types and levels of competition for resources between people and wildlife; people's perceptions of and attitudes toward wildlife, including animals that forage on crops; and discourse about animals and their behaviors and how these discourses can be used for expressing dissent and distress about other social conflicts. So, to understand and respond to conflicts about crop damage, we need to look beyond what people lose, i.e., crop loss and economic equivalence, and focusmore on what people say about wildlife and why they say it.
Apex predators can suppress smaller bodied “mesopredators.” In doing so, they can provide refuge to species preyed upon by mesopredators, which is particularly important in regions where mesopredators are invasive. While most studies of mesopredator suppression focus on the response of mesopredators to human control of apex predators, other factors—including natural and anthropogenic disturbance—also drive the occurrence of apex predators and, in doing so, might shape spatial patterns of mesopredator suppression.
We examined the role of fire in shaping the occurrence of an apex predator and, by extension, mesopredators and small mammals in a fire‐prone region of semiarid Australia. We measured the activity of an apex predator (the dingo Canis dingo ); an invasive mesopredator it is known to suppress (the red fox Vulpes vulpes ); and two species of native small mammal (Mitchell's hopping mouse Notomys mitchelli ; silky mouse Pseudomys apodemoides ) that are potential prey, across 21 fire mosaics (each 12.56 km ² ). We used piecewise structural equation modelling and scenario analysis to explore the interactions between fire, predators and prey.
We found that dingoes were affected by fire history at the landscape scale, showing a preference for recently burned areas. While foxes were not directly affected by fire history, a negative association between dingoes and foxes meant that fire had an indirect impact on foxes, mediated through dingoes. Despite the suppression of foxes by dingoes, we did not observe a trophic cascade as small mammals were not negatively associated with foxes or positively associated with dingoes.
Synthesis and applications . Disturbance regimes have the capacity to shape patterns of mesopredator suppression when they alter the distributions of apex predators. Environmental change that promotes native predators can therefore help suppress mesopredators—a common conservation objective in regions with invasive mesopredators. The indirect consequences of disturbance regimes should be considered when managing disturbance (e.g. fire) for biodiversity conservation.
Moist evergreen forests of southwestern Ethiopia host high levels of biodiversity and have a high economic value due to coffee production. Coffee is a native shrub that is harvested under different management systems; its production can have both beneficial and detrimental effects for biodiversity. We investigated how bird community composition and richness, and abundance of different bird groups responded to different intensities of coffee management and the landscape context. We surveyed birds at 66 points in forest habitat with different intensities of coffee management and at different distances from the forest edge. We explored community composition using detrended correspondence analysis in combination with canonical correspondence analysis and indicator species analysis, and used generalized linear mixed models to investigate the responses of different bird groups to coffee management and landscape context. Our results show that (1) despite considerable bird diversity including some endemics, species turnover in the forest was relatively low; (2) total richness and abundance of birds were not affected by management or landscape context; but (3) the richness of forest and dietary specialists increased with higher forest naturalness, and with increasing distance from the edge and amount of forest cover. These findings show that traditional shade coffee management practices can maintain a diverse suite of forest birds. To conserve forest specialists, retaining undisturbed, remote forest is particularly important, but structurally diverse locations near the forest edge can also harbour a high diversity of specialists.
Global biodiversity loss is a critical environmental crisis, yet the lack of spatial data on biodiversity threats has hindered conservation strategies. Theory predicts that abrupt biodiversity declines are most likely to occur when habitat availability is reduced to very low levels in the landscape (10-30%). Alternatively, recent evidence indicates that biodiversity is best conserved by minimizing human intrusion into intact and relatively unfragmented landscapes. Here we use recently available forest loss data to test deforestation effects on International Union for Conservation of Nature Red List categories of extinction risk for 19,432 vertebrate species worldwide. As expected, deforestation substantially increased the odds of a species being listed as threatened, undergoing recent upgrading to a higher threat category and exhibiting declining populations. More importantly, we show that these risks were disproportionately high in relatively intact landscapes; even minimal deforestation has had severe consequences for vertebrate biodiversity. We found little support for the alternative hypothesis that forest loss is most detrimental in already fragmented landscapes. Spatial analysis revealed high-risk hot spots in Borneo, the central Amazon and the Congo Basin. In these regions, our model predicts that 121-219 species will become threatened under current rates of forest loss over the next 30 years. Given that only 17.9% of these high-risk areas are formally protected and only 8.9% have strict protection, new large-scale conservation efforts to protect intact forests are necessary to slow deforestation rates and to avert a new wave of global extinctions.
Context
Cultural landscapes provide essential ecosystem services to local communities, especially in poor rural settings. However, potentially negative impacts of ecosystems—or disservices—remain inadequately understood. Similarly, how benefit–cost outcomes differ within communities is unclear, but potentially important for cultural landscape management.
Objectives
Here we investigated whether distinct forest ecosystem service–disservice outcomes emerge within local communities. We aimed to characterize groups of community members according to service–disservice outcomes, and assessed their attitudes towards the forest.
Methods
We interviewed 150 rural households in southwestern Ethiopia about locally relevant ecosystem services (provisioning services) and disservices (wildlife impacts). Households were grouped based on their ecosystem service–disservice profiles through hierarchical clustering. We used linear models to assess differences between groups in geographic and socioeconomic characteristics, as well as attitudes toward the forest.
Results
We identified three groups with distinct ecosystem service–disservice profiles. Half of the households fell into a “lose–lose” profile (low benefits, high costs), while fewer had “lose–escape” (low benefits, low costs) and “win–lose” (high benefits, high costs) profiles. Location relative to forest and altitude explained differences between the “lose–escape” profile and other households. Socioeconomic factors were also important. “Win–lose” households appeared to be wealthier and had better forest use rights compared to “lose–lose” households. Attitudes towards the forest did not differ between profiles.
Conclusions
Our study demonstrates the importance of disaggregating both ecosystem services and disservices, instead of assuming that communities receive benefits and costs homogenously. To manage cultural landscapes sustainably, such heterogeneity must be acknowledged and better understood.
Research suggests that the scale of human population and the current pace of its growth contribute substantially to the loss of biological diversity. Although technological change and unequal consumption inextricably mingle with demographic impacts on the environment, the needs of all human beings—especially for food—imply that projected population growth will undermine protection of the natural world. Numerous solutions have been proposed to boost food production while protecting biodiversity, but alone these proposals are unlikely to staunch biodiversity loss. An important approach to sustaining biodiversity and human well-being is through actions that can slow and eventually reverse population growth: investing in universal access to reproductive health services and contraceptive technologies, advancing women’s education, and achieving gender equality.
Unprecedented global human population growth and rapid urbanization of rural and natural lands highlight the urgent need to integrate biodiversity conservation into planning for urban growth. A challenging question for applied ecologists to answer is: What pattern of urban growth meets future housing demand whilst minimizing impacts on biodiversity?
We quantified the consequences for mammals of meeting future housing demand under different patterns of compact and dispersed urban growth in an urbanizing forested landscape in south‐eastern Australia. Using empirical data, we predicted impacts on mammals of urban growth scenarios that varied in housing density (compact versus dispersed) and location of development for four target numbers of new dwellings.
We predicted that compact developments (i.e. high‐density housing) reduced up to 6% of the area of occupancy or abundance of five of the six mammal species examined. In contrast, dispersed developments (i.e. low‐density housing) led to increased mammal abundance overall, although results varied between species: as dwellings increased, the abundance or occurrence of two species increased (up to ∼100%), one species showed no change, and three species declined (up to ∼39%).
Two ground‐dwelling mammal species ( Antechinus stuartii and Rattus fuscipes ) and a tree‐dwelling species ( Petaurus australis ) were predicted to decline considerably under dispersed rather than compact development. The strongest negative effect of dispersed development was for Petaurus australis (a species more abundant in forested interiors) which exhibited up to a 39% reduction in abundance due to forest loss and an extended negative edge effect from urban settlements into adjacent forests.
Synthesis and applications . Our findings demonstrate that, when aiming to meet demand for housing, any form of compact development (i.e. high‐density housing) has fewer detrimental impacts on forest‐dwelling mammals than dispersed development (i.e. low‐density housing). This is because compact development concentrates the negative effects of housing into a small area whilst at the same time preserving large expanses of forests and the fauna they sustain. Landscape planning and urban growth policies must consider the trade‐off between the intensity of the threat and area of sprawl when aiming to reduce urbanization impacts.
Significance
Nature is increasingly threatened by rapid infrastructure expansion. For the first time, to our knowledge, we quantify the high pervasiveness of transportation infrastructure in all European countries. Unfortunately, spatial definition of the areas ecologically affected by infrastructure at large scales is complicated. Thus, we present a method for assessing the spatial extent of the impacts on birds and mammals at regional and national scales. As an illustration, its application to Spain shows that most of the country is affected, predicting moderate and severe declines for birds and mammals, respectively. The lack of areas that could be used as controls implies that scientists may no longer be able to measure the magnitude of road effects on wide-ranging mammals in most of Europe.
The leopard’s (Panthera pardus) broad geographic range, remarkable adaptability, and secretive nature have contributed to a misconception that this species might not be severely threatened across its range. We find that not only are several subspecies and regional populations critically endangered but also the overall range loss is greater than the average for terrestrial large carnivores. To assess the leopard’s status, we compile 6,000 records at 2,500 locations from over 1,300 sources on its historic (post 1750) and current distribution. We map the species across Africa and Asia, delineating areas where the species is confirmed present, is possibly present, is possibly extinct or is almost certainly extinct. The leopard now occupies 25-37% of its historic range, but this obscures important differences between subspecies. Of the nine recognized subspecies, three (P. p. pardus, fusca, and saxicolor) account for 97% of the leopard’s extant range while another three (P. p. orientalis, nimr, and japonensis) have each lost as much as 98% of their historic range. Isolation, small patch sizes, and few remaining patches further threaten the six subspecies that each have less than 100,000 km2 of extant range. Approximately 17% of extant leopard range is protected, although some endangered subspecies have far less. We found that while leopard research was increasing, research effort was primarily on the subspecies with the most remaining range whereas subspecies that are most in need of urgent attention were neglected.
We assessed the impacts of crop raiding by wild mammals on the livelihoods of smallholding farmers in south-western Ethiopia. Data were generated through participatory field mapping, interviews and focus groups. The results indicated that wild mammals, mainly olive baboons Papio anubis and bush pigs Potamochoerus larvatus, were raiding most crops cultivated in villages close to forests. In addition to the loss of crops, farmers incurred indirect costs in having to guard and cultivate plots far from their residences, sometimes at the expense of their children’s schooling. Raiding also undermined farmers’ willingness to invest in modern agricultural technologies. Various coping strategies, including guarding crops and adapting existing local institutions, were insufficient to reduce raiding and its indirect impacts on household economies to tolerable levels, and were undermined by existing policies and government institutions. It is essential to recognize wild mammal pests as a critical ecosystem disservice to farmers, and to identify ways to mitigate their direct and indirect costs, to facilitate local agricultural development and livelihood security, and integrate wildlife conservation and local development more fully in agriculture–forest mosaic landscapes.
The intertwined challenges of food insecurity, deforestation, and biodiversity loss remain perennial challenges in Ethiopia, despite increasing policy interventions. This thesis investigates smallholding farmers’ tree- and forest-based livelihoods and management practices, in the context of national development and conservation policies, and examines how these local management practices and policies transform the agriculture–forest mosaic landscapes of southwestern Ethiopia.
The thesis is guided by a political ecology perspective, and focuses on an analytical framework of ecosystem services (ESs) and disservices (EDs). It uses a mixed research design with data from participatory field mapping, a tree ‘inventory’, interviews, focus group discussions, population censuses, and analysis of satellite images and aerial photos.
The thesis presents four papers. Paper I investigates how smallholding farmers in an agriculture–forest mosaic landscape manage trees and forests in relation to a few selected ESs and EDs that they consider particularly beneficial or problematic. The farmers’ management practices were geared towards mitigating tree- and forest-related EDs such as wild mammal crop raiders, while at the same time augmenting ESs such as shaded coffee production, resulting in a restructuring of the agriculture–forest mosaic. Paper II builds further on the EDs introduced in paper I, to assess the effects of crop raids by forest-dwelling wild mammals on farmers’ livelihoods. The EDs of wild mammals and human–wildlife conflict are shown to constitute a problem that goes well beyond a narrow focus on yield loss. The paper illustrates the broader impacts of crop-raiding wild mammals on local agricultural and livelihood development (e.g. the effects on food security and children’s schooling), and how state forest and wildlife control and related conservation policy undermined farmers’ coping strategies. Paper III examines local forest-based livelihood sources and how smallholders’ access to forests is reduced by state transfer of forestland to private companies for coffee investment. This paper highlights how relatively small land areas appropriated for investment in relatively densely inhabited areas can harm the livelihoods of many farmers, and also negatively affect forest conservation. Paper IV investigates the patterns and drivers of forest cover change from 1958 to 2010. Between 1973 and 2010, 25% of the total forest was lost, and forest cover changes varied both spatially and temporally. State development and conser-vation policies spanning various political economies (feudal, socialist, and ‘free market-oriented’) directly or indirectly affected local ecosystem use, ecosystem management practices, and migration processes. These factors (policies, local practices, and migration) have thus together shaped the spatial patterns of forest cover change in the last 50 years.
The thesis concludes that national development and conservation policies and the associated power relations and inequality have often undermined local livelihood security and forest conservation efforts. It also highlights how a conceptualization of a local ecosystem as a provider of both ESs and EDs can generate an understanding of local practices and decisions that shape development and conservation trajectories in mosaic landscapes. The thesis draws attention to the need to make development and conservation policies relevant and adaptable to local conditions as a means to promote local livelihood and food security, forest and biodiversity conservation, and ESs generated by agricultural mosaic landscapes.
Keywords: conservation, deforestation, ecosystem disservices, ecosys-tem services, forest, Ethiopia, land grabbing, livelihood, Oromia, policies, political ecology, trees, tropical landscape mosaic
http://www.diva-portal.org/smash/get/diva2:915593/FULLTEXT02.pdf
The Millennium Ecosystem Assessment identified habitat loss due to the extensive growth of agriculture as the primary driver of biodiversity loss. One implication of this is that agricultural intensification has the potential to reduce threats to wild species. In this paper we consider the evidence for differences in the threat to biodiversity posed by the intensive and extensive growth of agriculture in Sub-Saharan Africa. Using data on numbers of endemic species weighted by overall threat status, we analyze the impact of agricultural productivity growth and agricultural land conversion in 27 countries on threats to mammal, bird and plant species over two time scales: one covering the period since agricultural and environmental records began, the other covering the last decade. We find that the extensive growth of agriculture is associated with increasing threats to biodiversity at all time scales. While intensification is associated with a significant reduction in the threat to all species on long time scales, however, we find that it has no significant effect on shorter time scales.
1.Debates about “land-sparing” and “land-sharing” strategies for conserving biodiversity in cities provide an overly simplistic characterization of alternative planning options. Increased urbanization manifests in a number of ways and sophisticated analyses of how species respond to urban environments are required before generalizations about the relative merits of either planning strategy should be made.2.We investigated how insectivorous bats respond to housing density (a measure of urbanization intensity) and a range of habitat variables by modelling the occupancy and activity of 12 species in Melbourne, Australia. In addition to species-level analyses, species were grouped into guilds (“matrix”, “patch” or “edge” species) depending on their ecomorphology and level of patch-dependency.3.Housing density (dwellings per hectare: dph) was the dominant explanatory variable of occupancy and activity of most species studied. Site occupancy probabilities of patch and edge species were reduced by half at housing densities of just 1.1–4.5 dph depending on species, while their activity was halved at housing densities of 2.6–10.3 dph. The activity of two matrix species also declined, but at higher housing densities (reducing by half at 4.5–7.9 dph). Patch and edge species responded non-linearly to tree cover at low housing densities, with peaks in occupancy and activity at 20–60%. This response broke down at medium housing densities, however, as most species were no longer present.4.Synthesis and applications. Occupancy probability and activity of almost all bat species studied were substantially reduced even at very low housing densities. Increasing tree cover had no positive effect on the occupancy and activity of patch and edge species once medium housing densities were reached. In order for land-sharing strategies to provide good habitat for patch and edge bat species housing densities would need to be so low as to be impractical in most urban planning contexts. By contrast, land-sparing with forested habitat remaining in 20% or more of the landscape could provide positive conservation outcomes for the species modelled here. We discuss the relevance of our findings to planning for conservation of bats and their habitats in other recently established and expanding cities.This article is protected by copyright. All rights reserved.
Increasing housing density is generally assumed to confer negative effects on forest breeding birds. This implies we should build at low density over the landscape to conserve these species. However, for a given human population, low-density development must cover a large area, resulting in sprawl. A pertinent question is then: at what housing density are the impacts of a given human population on forest biodiversity minimised? For a given human population, it is unclear whether the impacts on forest biodiversity are less where housing density is high and sprawl area is small or where housing density is low and sprawl area is large. We addressed this question using the abundance, species richness and evenness of forest birds in Ottawa, Ontario and Gatineau, Quebec, Canada. First, we counted breeding birds at 22 sites representing a range of housing densities. We then used these empirical measurements to estimate forest bird abundance, species richness and evenness in four hypothetical development scenarios representing the trade-off between housing density and sprawl area. With the exception of the Undeveloped scenario (i.e., continuous forest), forest birds and forest interior birds were most abundant in the Compact scenario and most speciose in the Semi-compact scenario, whereas forest edge birds were most abundant and speciose in the Dispersed scenario. All three bird groups were most even in the Compact scenario. We conclude that compact housing development (building at high density over a small area) minimises the impacts of a given human population on forest breeding birds.
Ecological research uses data collection techniques that are prone to substantial and unique types of measurement error to address scientific questions about species abundance and distribution. These data collection schemes include a number of survey methods in which unmarked individuals are counted, or determined to be present, at spatially- referenced sites. Examples include site occupancy sampling, repeated counts, distance sampling, removal sampling, and double observer sampling. To appropriately analyze these data, hierarchical models have been developed to separately model explanatory variables of both a latent abundance or occurrence process and a conditional detection process. Because these models have a straightforward interpretation paralleling mechanisms under which the data arose, they have recently gained immense popularity. The common hierarchical structure of these models is well-suited for a unified modeling interface. The R package unmarked provides such a unified modeling framework, including tools for data exploration, model fitting, model criticism, post-hoc analysis, and model comparison.
Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest-agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973-2010) across elevations in 2 forest-agriculture mosaic landscapes (1100 km(2) around Bonga and 3000 km(2) in Goma-Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee-growing elevations compared with at higher elevations (-10/20% vs. -40/50% comparing relative rates at 1800 m asl and 2300-2500 m asl, respectively). Within the coffee-growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest-specialist species. Even if the presence of coffee slows down the conversion of forest to annual-crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques.
Crop loss to wildlife impedes local support for conservation efforts at Kibale National Park, Uganda. Systematic monitoring of crop loss to wildlife (mammals larger than 3 kg) and livestock was conducted in six villages around Kibale over a 2-year period. Five wildlife species accounted for 85% of crop damage events: baboons, bushpigs, redtail monkeys, chimpanzees, and elephants. Marked variation in frequency, and extent of damage is reported within villages, between villages, and between wildlife species. Fields lying within 500 m of the forest boundary lost 4-7% of crops per season on average, but the distribution of damage was highly skewed such that maize and cassava fields were on occasion completely destroyed. Multivariate analysis was used to test predictors of damage, including human population density guarding, hunting, sight distance, and distance from the forest. Tests were performed at two levels of analysis, field and village. Distance from the forest edge explained the greatest amount of variation in crops damage, although hunting also influenced the extent of crop damage Elephants inflicted catastrophic damage to farms but their forays were rare and highly localized. Livestock caused considerable damage to crops but farmers seldom complained because they had institutionalized modes of restitution. Although most of the crop damage by wildlife is restricted To a narrow band of farmers living near the forest edge, risk perception among these farmers has been amplified by legal prohibitions on killing wild animals Elevating local tolerance for wildlife will require diverse approaches, including channeling economic benefits to Kibale's neighbors and providing compensation in limited cases.
1. Calibrating indices of animal abundance to true densities is critical in wildlife studies especially when direct density estimations are precluded by high costs, lack of required data or model parameters, elusiveness and rarity of target species. For studies deploying camera traps, the use of photographic rate (photographs per sampling time) as an index of abundance potentially applies to the majority of terrestrial mammals where individual recognition, and hence capture–recapture analysis, are unfeasible. The very few studies addressing this method have either been limited by lack of independence between trapping rates and density estimations, or because they combined different species, thus introducing potential bias in camera trap detection rates. This study uses a single model species from several sites to analyse calibration of trapping rates to independently derived estimations of density. The study also makes the first field test of the method by Rowcliffe et al. (2008) for density derivation from camera trapping rates based on modelling animal-camera contacts.
Coffea arabica L. is native to the Afromontane forests of Ethiopia. The local communities living in and around the forests manage the forest in traditional ways for coffee production. The level of management practices ranges from the relatively undisturbed forest coffee (FC), where little or no human inference is observed to the disturbed semi-forest coffee (SFC) system. This study analyzes the effects of wild coffee management on the floristic diversity and vegetation structure in these systems, in the Berhane-Kontir and Harenna forest sites. A total 114 quadrats, of 20 m × 20 m were laid along transects in both forest sites. Species richness was highest in the FC and lowest in the SFC system although the scale varies between the two forests. Shannon diversity and evenness indices exhibit high variation between the two forest systems and the lowest in the SFC system. The type of growth-form dominance also varies between the two forest systems, with up to 50% reduction in the number of species of lianas, small trees and shrubs were observed in the SFC system. In the SFC system in both forests, coffee plants occupy greater than 88% of plant density in the diameter class between 2 and 10 cm compared to less than 23% in the FC system. The ordination analysis also demonstrates the importance of human management influence and shows clear distinction between the FC and SFC plots of both forests. The continuous wild coffee management in the SFC system suppresses tree regeneration, reduces tree density and eventually leads to the disappearance of forest species, while promoting coffee plants. Therefore, conservation strategies of the Afromontane forest with wild coffee populations should focus on the balance between plant diversity and coffee production.
Tropical forest ecosystems harbor high biodiversity, but they have suffered from ongoing human-induced degradation. We investigated the conservation value of moist evergreen Afromontane forest sites across gradients of site-level disturbance, landscape context and forest history in southwestern Ethiopia. We surveyed woody plants at 108 randomly selected sites and grouped them into forest specialist, pioneer, and generalist species. First, we investigated if coffee dominance, current distance from the forest edge, forest history, heat load and altitude structured the variation in species composition using constrained correspondence analysis. Second, we modelled species richness in response to the same explanatory variables. Our findings show that woody plant community composition was significantly structured by altitude, forest history, coffee dominance and current distance from forest edge. Specifically, (1) total species richness and forest specialist species richness were affected by coffee management intensity; (2) forest specialist species richness increased, while pioneer species decreased with increasing distance from the forest edge; and (3) forest specialist species richness was lower in secondary forest compared to in primary forest. These findings show that coffee management intensity, landscape context and forest history in combination influence local and landscape level biodiversity. We suggest conservation strategies that foster the maintenance of large undisturbed forest sites and that prioritize local species in managed and regenerating forests. Creation of a biosphere reserve and shade coffee certification could be useful to benefit both effective conservation and people's livelihoods.
In tropical regions the extent of agricultural land is increasing rapidly at the expense of natural forest, with associated losses of biodiversity and ecosystem services. Agroforestry has long been proposed as a more sustainable agricultural system, conserving biodiversity while providing significant local livelihoods. In this context, camera traps were deployed to compare communities of large mammals between natural forest (22,272 hours across 24 deployments) and extensively managed coffee forest (19,059 hours, 23 deployments) for the first time in the south-west Ethiopian highlands. Mammal communities in the two forest types were similar in species richness and Shannon diversity but differed in community composition. Significant indicator species of coffee forest were the crested porcupine Hystrix cristata and the Ethiopian hare Lepus fagani, whereas leopards Panthera pardus and civets Civettictis civetta had a preference for natural forest. The number of detections of mammals was higher in coffee forest, where activity patterns were predominantly crepuscular and nocturnal, which may be a direct adaptation to frequent human disturbance. In natural forest, mammal activity peaked during daytime. Despite the high mammal diversity in extensively managed coffee forest, it cannot fully replace natural forest as a habitat for large mammals. We suggest that a balanced landscape mosaic of coffee and natural forest may be a valuable combination for both conservation and coffee cultivation.
Nocturnal refuge
As the human population grows, there are fewer places for animals to live out their lives independently of our influence. Given our mostly diurnal tendencies, one domain that remains less affected by humans is the night. Gaynor et al. found that across the globe and across mammalian species—from deer to coyotes and from tigers to wild boar—animals are becoming more nocturnal (see the Perspective by Benítez-López). Human activities of all kinds, including nonlethal pastimes such as hiking, seem to drive animals to make use of hours when we are not around. Such changes may provide some relief, but they may also have ecosystem-level consequences.
Science , this issue p. 1232 ; see also p. 1185
Conservation of biodiversity in urban environments depends on species’ responses to the intensity of urban development. “Land sharing” and “land sparing” represent alternate ends of a gradient that conceptualises a trade‐off between the human population and biodiversity. We used a linear optimisation procedure to (a) identify the optimal allocation of land for people and nature, (b) assess whether the optimal allocation is closer to land sparing or land sharing and (c) examine how this might change under scenarios of human population growth.
We surveyed birds in 28 landscapes, each 25 ha in size, along a gradient of human population density (zero to c . 1,600 persons/25 ha) in the Greater Melbourne region, Australia. Species’ responses to population density were estimated using generalised additive models ( GAM s). These relationships were then used to determine the optimal allocation of land among different categories of population density based on maximising a community index, the geometric mean of relative abundance ( G ) of bird species.
Human population density was an important driver of the reporting rate for 28 species. Response curves differed among “urban avoider,” “urban adapter” and “urban exploiter” species. For the current human population in the study area, the optimal allocation of land included elements of both land sharing and land sparing. However, for scenarios of increased population size, optimal allocation converged upon a land sparing design.
Synthesis and applications . Urban areas represent a mosaic of land uses that offer habitats of differing quality. Land sharing, based on sustaining biota among residential areas, performed poorly under all scenarios due to its inability to support species that depend on natural or seminatural habitat. To sustain more than a homogenised avifauna in urban regions, large tracts of natural vegetation are needed within, or adjacent to, the urban environment. Protecting natural areas on urban fringes will be critical to the safeguarding of nature in the future as urban populations and land‐use inevitably expand.
The human population is rapidly urbanizing, and the negative impacts of urban cover on biodiversity and ecosystem function are expected to increase. Trophic dynamics have been hypothesized to change with urbanization, with consequences for biodiversity and function. Here, I review recent progress in this area by focusing on how urbanization affects dietary sources, trophic interactions and the functional ecology of synanthropic species.
Urbanization affects primary autochthonous production in terrestrial and aquatic ecosystems by replacing and fragmenting natural areas with impervious cover, increasing nutrient supply, changing hydrological regimes, and altering the composition and seasonality of primary producers. The responses of primary production differ between climatic regions or across hydrological regimes.
Urbanization can also change the availability of subsidies (autochthonous vs. allochthonous resources) because many urban species feed on human food (anthropogenic subsidies) and because of changes in the plant composition and physical characteristics of riparian zones.
Urbanization can change the composition of consumers by decreasing the abundance of apex predators, releasing mesopredators, as well as the introduction of non‐native omnivores.
Few direct experiments have been conducted on trophic interactions in urban ecosystems. They broadly suggest that urbanization weakens herbivory and predation, but that it might increase competition between synanthropic and urbanophobic species. However, the outcomes of these interactions are highly context‐specific.
The reliance of synanthropic species on anthropogenic subsidies appears to be an important aspect of urban trophic ecology. However, more research is needed to understand how dietary flexibility, especially in relation to anthropogenic subsidies, contributes to the physiology and population dynamics of synanthropes.
Urbanization can dramatically change trophic dynamics in the urban ecosystem with implications for biodiversity patterns, management and conservation. However, it is clear that a broader and more mechanistic understanding of the urban food webs is needed. This can be accomplished through inclusion of functional trophic metrics in monitoring efforts, the use of stable isotope food web metrics, the use of multi‐trophic‐level experiments and a more detailed study of the functional ecology of synanthropes.
A plain language summary is available for this article.
Hunting is a major driver of biodiversity loss, but a systematic large-scale estimate of huntinginduced
defaunation is lacking.We synthesized 176 studies to quantify hunting-induced
declines of mammal and bird populations across the tropics. Bird and mammal abundances
declined by 58% (25 to 76%) and by 83% (72 to 90%) in hunted compared with unhunted
areas. Bird and mammal populations were depleted within 7 and 40 kilometers from hunters’
access points (roads and settlements). Additionally, hunting pressure was higher in areas with
better accessibility to major towns where wild meat could be traded. Mammal population
densities were lower outside protected areas, particularly because of commercial hunting.
Strategies to sustainablymanage wildmeat hunting in both protected and unprotected tropical
ecosystems are urgently needed to avoid further defaunation.
The first edition of this book has established itself as one of the leading references on generalized additive models (GAMs), and the only book on the topic to be introductory in nature with a wealth of practical examples and software implementation. It is self-contained, providing the necessary background in linear models, linear mixed models, and generalized linear models (GLMs), before presenting a balanced treatment of the theory and applications of GAMs and related models. The author bases his approach on a framework of penalized regression splines, and while firmly focused on the practical aspects of GAMs, discussions include fairly full explanations of the theory underlying the methods. Use of R software helps explain the theory and illustrates the practical application of the methodology. Each chapter contains an extensive set of exercises, with solutions in an appendix or in the book’s R data package gamair, to enable use as a course text or for self-study.
Significance
The planet’s large, growing, and overconsuming human population, especially the increasing affluent component, is rapidly eroding many of the Earth’s natural ecosystems. However, society’s only real policy lever to reduce the human population humanely is to encourage lower per capita fertility. How long might fertility reduction take to make a meaningful impact? We examined various scenarios for global human population change to the year 2100 by adjusting fertility and mortality rates (both chronic and short-term interventions) to determine the plausible range of outcomes. Even one-child policies imposed worldwide and catastrophic mortality events would still likely result in 5–10 billion people by 2100. Because of this demographic momentum, there are no easy ways to change the broad trends of human population size this century.
As people encroach increasingly on natural areas, one question is how this affects avian biodiversity. The answer to this is partly scale-dependent. At broad scales, human populations and biodiversity concentrate in the same areas and are positively associated, but at local scales people and biodiversity are negatively associated with biodiversity. We investigated whether there is also a systematic temporal trend in the relationship between bird biodiversity and housing development. We used linear regression to examine associations between forest bird species richness and housing growth in the conterminous United States over 30 years. Our data sources were the North American Breeding Bird Survey and the 2000 decennial U.S. Census. In the 9 largest forested ecoregions, housing density increased continually over time. Across the conterminous United States, the association between bird species richness and housing density was positive for virtually all guilds except ground nesting birds. We found a systematic trajectory of declining bird species richness as housing increased through time. In more recently developed ecoregions, where housing density was still low, the association with bird species richness was neutral or positive. In ecoregions that were developed earlier and where housing density was highest, the association of housing density with bird species richness for most guilds was negative and grew stronger with advancing decades. We propose that in general the relationship between human settlement and biodiversity over time unfolds as a 2-phase process. The first phase is apparently innocuous; associations are positive due to coincidence of low-density housing with high biodiversity. The second phase is highly detrimental to biodiversity, and increases in housing density are associated with biodiversity losses. The long-term effect on biodiversity depends on the final housing density. This general pattern can help unify our understanding of the relationship of human encroachment and biodiversity response.Patrones Sistemáticos Temporales en la Relación entre Desarrollos Urbanos y la Biodiversidad de Aves de BosqueResumenMientras la gente invade cada vez más las áreas naturales, una pregunta que surge es cómo afecta esto a la biodiversidad de aves. La respuesta depende parcialmente de escalas. Con escalas amplias, las poblaciones humanas y la biodiversidad se concentran en las mismas áreas y se asocian positivamente, pero en escalas locales la gente y la biodiversidad se asocian negativamente. Investigamos si también existe una tendencia sistemática temporal en la relación entre la biodiversidad de aves y el desarrollo urbano. Usamos una regresión lineal para examinar las asociaciones entre la riqueza de especies de aves de bosque y el crecimiento urbano en los Estados Unidos (exceptuando a Alaska y Hawái) a lo largo de 30 años. Nuestras fuentes de datos fueron el Censo Norteamericano de Aves Reproductoras y el censo estadunidense del año 2000. A lo largo de la parte de Estados Unidos que estudiamos, la asociación entre la riqueza de especies de aves y la densidad urbana fue positiva para virtualmente todos los gremios con excepción de las aves que anidan en el suelo. Encontramos una trayectoria sistemática de la declinación de la riqueza de especies de aves conforme aumentaba la urbanización con el tiempo. En las eco-regiones con desarrollo más reciente, donde la densidad urbana era aún baja, la asociación con la riqueza de especies de aves fue neutral o positiva. En las eco-regiones que se desarrollaron con anterioridad y donde la densidad urbana fue la más alta, la asociación de la densidad urbana con la riqueza de especies fue negativa con la mayoría de los gremios y se volvía más fuerte en las siguientes décadas. Proponemos que en general, la relación entre los asentamientos humanos y la biodiversidad ocurre a lo largo del tiempo como un proceso de 2 fases. La primera es aparentemente inocua: las asociaciones son positivas debido a la coincidencia entre la baja densidad urbana y la alta biodiversidad. La segunda fase es altamente dañina para la biodiversidad, y los incrementos en la densidad urbana están asociados con pérdidas en la biodiversidad. El efecto a largo plazo sobre la biodiversidad depende de la densidad urbana final. Este patrón general puede ayudar a unificar nuestro entendimiento de la relación entre la invasión humana y la respuesta de la biodiversidad.
Land degradation is affecting rural livelihoods across sub-Saharan Africa. Promoting sustainable land management requires a thorough understanding of land use change drivers, processes and effects. However, in most African countries reliable data for such investigations are missing. We therefore test an integrated approach to analyse land use dynamics, combining remote sensing images, an in-depth quantitative survey, stakeholder interviews and local statistics. We analyse land dynamics and agricultural production over a 25-year period in Vihiga District, Western Kenya. Specifically, we examine how land use has changed in this period, the main drivers for land use change, and the main effects of these changes on agricultural production. Vihiga District is one of the most densely populated rural areas in Africa. We find that the district has undergone rapid land use change in the past 25 years. In particular, there has been a major conversion of forest and bare land to agricultural land use. Often, it is stated that increasing population pressure triggers agricultural intensification; however, we find little evidence of such a process in Vihiga District. Productivity of tea and, to a lesser extent, vegetables increased but the yields of maize and beans, the most common crops, fluctuated around a ton per hectare. Overall, per capita food crop production dropped by 28% during the past two decades. Our study shows that high and increasing population pressures do not necessarily lead to agricultural intensification, and that there is a need to consider more explicitly off-farm income in development and land management policies and projects.
1.As cities around the world rapidly expand, there is an urgent need to implement the best development form to minimise the negative impacts of urbanisation on native biodiversity. Two divergent forms for the expansion of cities are land-sharing and land-sparing developments. To date their relative benefits for biodiversity conservation are poorly understood.2.We quantified the relative conservation benefits of land-sharing and land-sparing developments for butterflies and ground beetles in Tokyo, Japan. For each insect species we determined which approach resulted in a larger total population size.3.At a higher level of urbanisation (higher number of buildings in a landscape), land-sparing rather than land-sharing resulted in a higher total population size for the majority species of both taxa. However, at a lower level of urbanisation, butterflies and ground beetles showed different responses to city development forms. Ground beetles had their highest total population sizes under land-sparing, whereas for butterflies, especially open-land and matrix-dwelling species, larger populations were achieved under land-sharing.4.The negative impacts of urbanisation on biodiversity differ greatly between land-sharing and land-sparing development forms. We also revealed that the relative conservation benefits of land-sharing and land-sparing depend on the level of urbanisation.5.Synthesis and applications. In areas that will be heavily urbanised in the future, city planners and policy makers should adopt approaches that follow a land-sparing strategy, and that keep large blocks of greenspace free from development. At lower levels of urbanisation, on the other hand, as land-sharing was suggested to be the better strategy for many butterfly species, a hybrid development form could be adopted that integrates areas of land-sharing and land-sparing, which might have the additional benefit of enhancing the delivery of some ecosystem services by bringing nature and people closer together in some areas.This article is protected by copyright. All rights reserved.
Forest loss and fragmentation are among the largest threats to forest-dwelling wildlife species today, and projected increases in human population growth are expected to increase these threats in the next century. We combined spatially-explicit growth models with wildlife distribution models to predict the effects of human development on 5 forest-dependent bird species in Vermont, New Hampshire, and Massachusetts, USA. We used single-species occupancy models to derive the probability of occupancy for each species across the study area in the years 2000 and 2050. Over half a million new housing units were predicted to be added to the landscape. The maximum change in housing density was nearly 30 houses per hectare; however, 30% of the towns in the study area were projected to add less than 1 housing unit per hectare. In the face of predicted human growth, the overall occupancy of each species decreased by as much as 38% (ranging from 19% to 38% declines in the worst-case scenario) in the year 2050. These declines were greater outside of protected areas than within protected lands. Ninety-seven percent of towns experienced some decline in species occupancy within their borders, highlighting the value of spatially-explicit models. The mean decrease in occupancy probability within towns ranged from 3% for hairy woodpecker to 8% for ovenbird and hermit thrush. Reductions in occupancy probability occurred on the perimeters of cities and towns where exurban development is predicted to increase in the study area. This spatial approach to wildlife planning provides data to evaluate trade-offs between development scenarios and forest-dependent wildlife species.
Urbanization causes severe environmental degradation and continues to increase in scale and intensity around the world, but little is known about how we should design cities to minimize their ecological impact. With a sprawling style of urban development, low intensity impact is spread across a wide area, and with a compact form of development intense impact is concentrated over a small area; it remains unclear which of these development styles has a lower overall ecological impact. Here, we compare the consequences of compact and sprawling urban growth patterns on bird distributions across the city of Brisbane, Australia. We predicted the impact on bird populations of adding 84 642 houses to the city in either a compact or sprawling design using statistical models of bird distributions. We show that urban growth of any type reduces bird distributions overall, but compact development substantially slows these reductions at the city scale. Urban-sensitive species particularly benefited from compact development at the city scale because large green spaces were left intact, whereas the distributions of nonnative species expanded as a result of sprawling development. As well as minimizing ecological disruption, compact urban development maintains human access to public green spaces. However, backyards are smaller, which impacts opportunities for people to experience nature close to home. Our results suggest that cities built to minimize per capita ecological impact are characterized by high residential density, with large interstitial green spaces and small backyards, and that there are important trade-offs between maintaining city-wide species diversity and people's access to biodiversity in their own backyard.
The remarkable large-mammal fauna of the Indonesian island of Sumatra is one of the most endangered on Earth and is threatened by rampant deforestation. We used remote sensing and biological surveys to study the effects of deforestation on populations of endangered large mammals in a Sumatran landscape. We measured forest loss and created a predictive model of deforestation for Bukit Barisan Selatan National Park and an unprotected buffer area based on satellite images between 1985 and 1999. We used automatic cameras to determine the distribution and relative abundance of tigers ( Panthera tigris sumatrae ), elephants ( Elephas maximus ), rhinoceros ( Dicerorhinus sumatrensis ), and tapirs ( Tapir indicus ). Between 1985 and 1999, forest loss within the park averaged 2% per year. A total of 661 km ² of forest disappeared inside the park, and 318 km ² were lost in a 10-km buffer, eliminating forest outside the park. Lowland forest disappeared faster than hill/montane forest ( by a factor of 6 ) and forests on gentle slopes disappeared faster than forests on steep slopes ( by a factor of 16 ). Most forest conversion resulted from agricultural development, leading to predictions that by 2010 70% of the park will be in agriculture and that by 2036 lowland forest habitat will be eliminated. Camera-trap data indicated avoidance of forest boundaries by tigers, rhinoceroses ( up to 2 km ), and elephants ( up to 3 km ). Classification of forest into core and peripheral forest based on mammal distribution suggests that, by 2010, core forest area for tigers and rhinoceros will be fragmented and reduced to 20% of remaining forest. Core forest area for elephants will be reduced to 0.5% of remaining forest. Halting forest loss has proven one of the most difficult and complex problems faced by Indonesia's conservation agencies today and will require a mix of enforcement, wise land-use strategies, increased education, capacity to manage, and new financing mechanisms.
Human-driven land-use changes increasingly threaten biodiversity, particularly in tropical forests where both species diversity and human pressures on natural environments are high. The rapid conversion of tropical forests for agriculture, timber production and other uses has generated vast, human-dominated landscapes with potentially dire consequences for tropical biodiversity. Today, few truly undisturbed tropical forests exist, whereas those degraded by repeated logging and fires, as well as secondary and plantation forests, are rapidly expanding. Here we provide a global assessment of the impact of disturbance and land conversion on biodiversity in tropical forests using a meta-analysis of 138 studies. We analysed 2,220 pairwise comparisons of biodiversity values in primary forests (with little or no human disturbance) and disturbed forests. We found that biodiversity values were substantially lower in degraded forests, but that this varied considerably by geographic region, taxonomic group, ecological metric and disturbance type. Even after partly accounting for confounding colonization and succession effects due to the composition of surrounding habitats, isolation and time since disturbance, we find that most forms of forest degradation have an overwhelmingly detrimental effect on tropical biodiversity. Our results clearly indicate that when it comes to maintaining tropical biodiversity, there is no substitute for primary forests.
Understanding the factors related to invasive exotic species distributions at broad spatial scales has important theoretical and management implications, because biological invasions are detrimental to many ecosystem functions and processes. Housing development facilitates invasions by disturbing land cover, introducing nonnative landscaping plants, and facilitating dispersal of propagules along roads. To evaluate relationships between housing and the distribution of invasive exotic plants, we asked (1) how strongly is housing associated with the spatial distribution of invasive exotic plants compared to other anthropogenic and environmental factors; (2) what type of housing pattern is related to the richness of invasive exotic plants; and (3) do invasive plants represent ecological traits associated with specific housing patterns? Using two types of regression analysis (best subset analysis and hierarchical partitioning analysis), we found that invasive exotic plant richness was equally or more strongly related to housing variables than to other human (e.g., mean income and roads) and environmental (e.g., topography and forest cover) variables at the county level across New England. Richness of invasive exotic plants was positively related to area of wildland-urban interface (WUI), low-density residential areas, change in number of housing units between 1940 and 2000, mean income, plant productivity (NDVI), and altitudinal range and rainfall; it was negatively related to forest area and connectivity. Plant life history traits were not strongly related to housing patterns. We expect the number of invasive exotic plants to increase as a result of future housing growth and suggest that housing development be considered a primary factor in plans to manage and monitor invasive exotic plant species.
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