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Integrating anthropogenic factors into regional-scale species distribution models-A novel application in the imperiled sagebrush biome
Abstract and Figures
Species distribution models (SDM) that rely on regional‐scale environmental variables will play a key role in forecasting species occurrence in the face of climate change. However, in the Anthropocene, a number of local‐scale anthropogenic variables, including wildfire history, land‐use change, invasive species, and ecological restoration practices can override regional‐scale variables to drive patterns of species distribution. Incorporating these human‐induced factors into SDMs remains a major research challenge, in part because spatial variability in these factors occurs at fine scales, rendering prediction over regional extents problematic. Here, we used big sagebrush (Artemisia tridentata Nutt.) as a model species to explore whether including human‐induced factors improves the fit of the SDM. We applied a Bayesian hurdle spatial approach using 21,753 data points of field‐sampled vegetation obtained from the LANDFIRE program to model sagebrush occurrence and cover by incorporating fire history metrics and restoration treatments from 1980 to 2015 throughout the Great Basin of North America. Models including fire attributes and restoration treatments performed better than those including only climate and topographic variables. Number of fires and fire occurrence had the strongest relative effects on big sagebrush occurrence and cover, respectively. The models predicted that the probability of big sagebrush occurrence decreases by 1.2% (95% CI; –6.9%, 0.6%) when one fire occurs and that increasing fires from zero to at least one fire would decrease cover by 44.7% (95% CI; –47.9%, –41.3%). Restoration practices increased the probability of big sagebrush occurrence but had minimal effect on cover. Our results demonstrate the potential value of including disturbance and land management along with climate in models to predict species distributions. As an increasing number of datasets representing land use history become available, we anticipate that our modeling framework will have broad relevance across a range of biomes and species.
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... Ecological niche modeling (ENM), sometimes referred to interchangeably with species distribution modeling, is an analytical method that allows researchers to use species' presence data to investigate patterns of environmental suitability for a species as a function of suites of environmental variables (Elith & Leathwick 2009;Requena-Mullor et al. 2019). Importantly, this modeling approach has also proven useful for identifying species vulnerability to climate change (Kumar 2012;Urbani et al. 2017;Wang et al. 2020), and has informed restoration efforts for a wide range of species of conservation concern (York et al. 2011;Friggens & Finch 2015;Clauzel & Godet 2020;Cotrina S anchez et al. 2021). ...
By 1985, approximately 400,000 ha of the keystone species Shinnery oak's ( Quercus havardii ) historic distribution had been eliminated for agricultural purposes across the southwestern United States. These trends indicate a need for targeted conservation and restoration efforts, especially considering the increased attention received for its role in providing habitat for endangered fauna. Setting spatially explicit conservation targets can be challenging for species with limited distributions, as the change in climate conditions over time may disconnect the relationship between environmental suitability and static, topo‐edaphic factors. Our objective was to identify areas for Shinnery oak restoration and conservation and explore the role climate plays in determining these areas while considering topo‐edaphic relationships. We constructed ecological niche models to estimate Shinnery oak's distribution under current climate conditions and temporally transferred our model using an ensemble‐mean of general circulation models to identify areas predicted to retain environmental suitability for Shinnery oak through 2100. The current distribution model was best informed by one climate and two topo‐edaphic variables. We created a second distribution model excluding topo‐edaphic variables to estimate future plant–climate relationships. Incorporating insights from models informed by both static (e.g. soil) and dynamic (e.g. climate) variables, we identified areas for conservation characterized by persistent climate suitability and high soil type suitability. Lastly, we incorporated data on land use and ownership to explore socio‐ecological influences on management decisions. By identifying areas of agreement between our modeled distributions and considering social context, we prioritized conservation areas where environmental suitability persists under changing conditions to facilitate restoration success.
... This loss has led to the local or regional extirpation of numerous sagebrush obligate and facultative species (Davies et al. 2011), and has promoted invasion by exotic annual grass, whose dominance initiates a cycle of increased fire frequency, further threatening the sagebrush steppe (Allen et al. 2011;Balch et al. 2013;D'Antonio and Vitousek 1992). Despite annual investment of millions of dollars to restore sagebrush landscapes via transplanting or seeding, rates of successful restoration are variable (Arkle et al. 2014;Davies et al. 2018;Requena-Mullor et al. 2019;Shriver et al. 2018;Simler-Williamson and Germino 2022), largely due to high seedling mortality (Cawker 1980). Sagebrush seed is often translocated over large geographic distances for restoration efforts (Davidson and Germino 2020;Innes 2019), outside of the abiotic and biotic environmental conditions to which its source population may be locally adapted. ...
Aims
Local adaptation of plant populations to soil biotic conditions may complicate ecosystem restoration if seeds used in reseeding efforts are sourced from a different population than the one that succumbed to disturbance. Furthermore, climatic conditions may mediate the interaction between plants and soil microbial communities. This study aimed to assess how the composition of the local soil fungal community affects Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis) growth and its resource allocation to shoot and root growth under different moisture-availability conditions.
Methods
We explored sagebrush growth responses to inoculation with wet-adapted versus dry-adapted sagebrush-associated fungal communities in a 7-month greenhouse experiment. Seeds were planted with inoculum isolated from rhizosphere soil from either a relatively wet or a dry sagebrush-dominated site and subjected to a moisture regime representative of either the wet or dry site. Biomass, root morphology, and fungal community composition were assessed.
Results
Wet and dry sites hosted distinct in-situ fungal communities, and inoculum derived from different sites generated compositionally different fungal assemblages in the seedlings’ rhizospheres during the growth period. Compared to sterilized inoculum controls, live inoculum from either site enhanced seedling biomass, but only when soil moisture simulated that of the inoculum’s source site. Dry-site inoculum also produced longer, finer roots under dry-site conditions.
Conclusions
Moisture similar to the fungal inoculum’s source was necessary for fungi to positively impact sagebrush growth and root characteristics. Applying fungal inoculum adapted to an intended restoration site’s moisture could help seedlings optimize water uptake and productivity, encouraging sagebrush establishment.
... Wildfires in the Great Basin may equally remove large and small vegetation from the landscape (Miller et al. 2013;Requena-Mullor et al. 2019;Mahood et al. 2023), inherently erasing or modifying structural patterns across multiple scales. Postdisturbance heterogeneity across scales is unequal and depends on vegetation properties. ...
Context
Dynamic feedbacks between physical structure and ecological function drive ecosystem productivity, resilience, and biodiversity maintenance. Detailed maps of canopy structure enable comprehensive evaluations of structure–function relationships. However, these relationships are scale-dependent, and identifying relevant spatial scales to link structure to function remains challenging.
Objectives
We identified optimal scales to relate structure heterogeneity to ecological resistance, measured as the impacts of wildfire on canopy structure, and ecological resilience, measured as native shrub recruitment. We further investigated whether structural heterogeneity can aid spatial predictions of shrub recruitment.
Methods
Using high-resolution imagery from unoccupied aerial systems (UAS), we mapped structural heterogeneity across ten semi-arid landscapes, undergoing a disturbance-mediated regime shift from native shrubland to dominance by invasive annual grasses. We then applied wavelet analysis to decompose structural heterogeneity into discrete scales and related these scales to ecological metrics of resilience and resistance.
Results
We found strong indicators of scale dependence in the tested relationships. Wildfire effects were most prominent at a single scale of structural heterogeneity (2.34 m), while the abundance of shrub recruits was sensitive to structural heterogeneity at a range of scales, from 0.07 – 2.34 m. Structural heterogeneity enabled out-of-site predictions of shrub recruitment (R² = 0.55). The best-performing predictive model included structural heterogeneity metrics across multiple scales.
Conclusions
Our results demonstrate that identifying structure–function relationships requires analyses that explicitly account for spatial scale. As high-resolution imagery enables spatially extensive maps of canopy heterogeneity, models for scale dependence will aid our understanding of resilience mechanisms in imperiled arid ecosystems.
... Despite the unequivocal scientific evidence of the negative impacts associated with the degradation of natural ecosystems, society fails to reduce the rate of species decline [1]. Climate and land use/land cover (LULC) changes are the main drivers shaping the terrestrial biological communities and leading to biodiversity loss in the Anthropocene [4][5][6][7][8]. The impacts of climate change are observed across numerous ecosystems and human systems worldwide. ...
European grasslands are among the most species-rich ecosystems on small spatial scales. However, human-induced activities like land use and climate change pose significant threats to this diversity. To explore how climate and land cover change will affect biodiversity and community composition in grassland ecosystems, we conducted joint species distribution models (SDMs) on the extensive vegetation-plot database sPlotOpen to project distributions of 1178 grassland species across Europe under current conditions and three future scenarios. We further compared model accuracy and computational efficiency between joint SDMs (JSDMs) and stacked SDMs, especially for rare species. Our results show that: (i) grassland communities in the mountain ranges are expected to suffer high rates of species loss, while those in western, northern and eastern Europe will experience substantial turnover; (ii) scaling anomalies were observed in the predicted species richness, reflecting regional differences in the dominant drivers of assembly processes; (iii) JSDMs did not outperform stacked SDMs in predictive power but demonstrated superior efficiency in model fitting and predicting; and (iv) incorporating co-occurrence datasets improved the model performance in predicting the distribution of rare species.
This article is part of the theme issue ‘Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere’.
The concept of the ecological niche is fundamental to understanding species distributions but it often overlooks the critical role of demography in shaping said distributions. Conversely, demographic theory has traditionally neglected how vital rates vary across environments, limiting our understanding of population dynamics across species’ ranges. Over 50 years ago, Maguire proposed conceptualising the ecological niche as composed of multiple “demographic niches” corresponding to separate vital rates such as survival, development, and reproduction. Despite its potential for ecological research, Maguire’s perspective never really took off. Here, we introduce the “demographic niche concept” (DNC), a contemporary evolution of Maguire’s perspective, integrating recent advances in niche theory and demography to formalise the DNC. We first outline the theoretical foundations of the DNC, focusing on vital rate variation along environmental gradients and its role in shaping ecological niches. We then formalise the definition of the DNC, explore how demographic niches and their boundaries are determined, and introduce a framework for applying the DNC in environmental and geographic spaces. Importantly, we present the DNC as a tool for conservation planning by improving our ability to identify critical areas where specific demographic processes are vital for species persistence or absent under global change. Throughout this review, we also explore methods for modelling and integrating demographic niches and discuss their relevance for addressing global challenges such as climate change. By integrating the ecological niche with demographic theory, we propose testable hypotheses on how and why vital rates vary within niche space, the current frontier of the DNC. Finally, we identify key knowledge gaps and suggest research directions to address these gaps. By advancing the conceptual and methodological tools of the DNC, this review establishes a foundation for future empirical research and applications, offering new directions for ecological theory and conservation amidst a changing world.
Note: V1 to V3 are the same. Multiple versions arose because the pre-print sever botched the formatting of the initial article
The concept of the ecological niche is fundamental to understanding species distributions but it often overlooks the critical role of demography in shaping said distributions. Conversely, demographic theory has traditionally neglected how vital rates vary across environments, limiting our understanding of population dynamics across species’ ranges. Over 50 years ago, Maguire proposed conceptualising the ecological niche as composed of multiple “demographic niches” corresponding to separate vital rates such as survival, development, and reproduction. Despite its potential for ecological research, Maguire’s perspective never really took off. Here, we introduce the “demographic niche concept” (DNC), a contemporary evolution of Maguire’s perspective, integrating recent advances in niche theory and demography to formalise the DNC. We first outline the theoretical foundations of the DNC, focusing on vital rate variation along environmental gradients and its role in shaping ecological niches. We then formalise the definition of the DNC, explore how demographic niches and their boundaries are determined, and introduce a framework for applying the DNC in environmental and geographic spaces. Importantly, we present the DNC as a tool for conservation planning by improving our ability to identify critical areas where specific demographic processes are vital for species persistence or absent under global change. Throughout this review, we also explore methods for modelling and integrating demographic niches and discuss their relevance for addressing global challenges such as climate change. By integrating the ecological niche with demographic theory, we propose testable hypotheses on how and why vital rates vary within niche space, the current frontier of the DNC. Finally, we identify key knowledge gaps and suggest research directions to address these gaps. By advancing the conceptual and methodological tools of the DNC, this review establishes a foundation for future empirical research and applications, offering new directions for ecological theory and conservation amidst a changing world.
Note: V1 to V3 are the same. Multiple versions arose because the pre-print sever botched the formatting of the initial article
The concept of the ecological niche is fundamental to understanding species distributions but it often overlooks the critical role of demography in shaping said distributions. Conversely, demographic theory has traditionally neglected how vital rates vary across environments, limiting our understanding of population dynamics across species’ ranges. Over 50 years ago, Maguire proposed conceptualising the ecological niche as composed of multiple “demographic niches” corresponding to separate vital rates such as survival, development, and reproduction. Despite its potential for ecological research, Maguire’s perspective never really took off. Here, we introduce the “demographic niche concept” (DNC), a contemporary evolution of Maguire’s perspective, integrating recent advances in niche theory and demography to formalise the DNC. We first outline the theoretical foundations of the DNC, focusing on vital rate variation along environmental gradients and its role in shaping ecological niches. We then formalise the definition of the DNC, explore how demographic niches and their boundaries are determined, and introduce a framework for applying the DNC in environmental and geographic spaces. Importantly, we present the DNC as a tool for conservation planning by improving our ability to identify critical areas where specific demographic processes are vital for species persistence or absent under global change. Throughout this review, we also explore methods for modelling and integrating demographic niches and discuss their relevance for addressing global challenges such as climate change. By integrating the ecological niche with demographic theory, we propose testable hypotheses on how and why vital rates vary within niche space, the current frontier of the DNC. Finally, we identify key knowledge gaps and suggest research directions to address these gaps. By advancing the conceptual and methodological tools of the DNC, this review establishes a foundation for future empirical research and applications, offering new directions for ecological theory and conservation amidst a changing world.
Note: V1 to V3 are the same. Multiple versions arose because the pre-print sever botched the formatting of the initial article
Alterations in land use and cover often stem from human activities, which play a significant role in global change. Scholars have delved deeply into the evolution and prediction of land use, yielding fruitful research outcomes. However, there is a lack of quantitative and comprehensive evaluations. This study uses CiteSpace bibliometric software to map the collaboration networks and keyword co-occurrence of relevant literature from the Web of Science (WOS) database from 2013 to 2022, revealing the evolution trends of academic collaboration and research hotspots in this field. This research fills the gap in the lack of quantitative analysis and comprehensive evaluation of the research outcomes in the field of land use evolution and prediction, providing a systematic and intuitive understanding of its research progress and frontiers. The research results indicate that: (1) Land use evolution and prediction literature volume and depth have increased over the past few years, and its development speed has accelerated substantially since 2017. (2) There is a concentration of research institutions and clear regional characteristics of their distribution. A research network has been established between the developed and developing countries. (3) The current research focuses on the driving factors of land use evolution, the prediction method model and the ecological environment impact brought by land use change, and the research heat continues to rise. For example, CA-Markov model and CLUE-S model are used to predict and simulate the spatial and temporal dynamics of land use change. (4) The future research trend is to predict possible future changes in land use by developing different future scenarios, including climate change, policy interventions and economic development. Based on bibliometric analysis, this paper provides in-depth insight and scientific basis for land resource management in the context of global change.
Objective
Phellodendron amurense, a special species in Northeast Asia, is the source of the wild medicinal Phellodendri Amurensis Cortex, the second-level key protection in China. Because of its dual value of medicine and timber, it has been cut in large quantities, resulting in a sharp decline in wild resources. It has been listed as a national first-class rare tree species. Here, we aim to plan protection area and wild tending area for Chinese P. amurense in the context of climate change.
Method
In this study, based on the Biomod2 model, the main environmental factors affecting the distribution and the potentially suitable areas of the current and future were investigated. Furthermore, the correlation between the main environmental factors and the chemical components was determined by full subset regression. Habitat quality and landscape pattern change were determined by InVEST and Fragstats software based on the land use data in 1980, 2000, and 2020. Then, Zonation software was used to plan the priority protection and wild tending areas.
Results
The results showed that in the future, the potential habitat of P. amurense will gradually move to the high latitude and high altitude areas in the northwest direction, and the high suitability area will decrease sharply. Since 1980, the habitat quality of P. amurense habitat has gradually deteriorated, and the fragmentation has gradually intensified. In the future, the central part of the Greater Khingan Mountains and the forest area of the Lesser Khingan Mountains will be the long-term stable sanctuary. Fengcheng City and Tonghua County are the most suitable for the wild tending areas.
Conclusion
The existing nature reserve only contains 6.01% of the priority protection area, so we propose to expand the area to cover a larger proportion of the sanctuary and implement management and restoration plans to increase the suitability and connectivity. These results can support the protection action and provide a reference and scientific basis for further research, rational development, and utilization of P. amurense.
Buchholzia coriacea seed extracts were screened for possible anti-trypanosomal activity in mice. Whole Buchholzia coriacea seed was successively extracted with 80% ethanol (EtOH) and partitioned in petroleum ether and ethyl acetate to obtained crude extracts. The flavonoid was extracted from crude ethanol extract using column chromatography. The crude extracts and flavonoids obtained were screened for in vivo antitrypanosomal activity. In the in vivo study, both the crudes and flavonoids extracts were separately orally administered to Trypanosomal brucei brucei infected mice after the establishment of parasitaemia. The animals were grouped into 9 groups of 4 mice each and were treated with respective dose levels as follows: Group 1 (Crude 1000mg/kg), Group 2 (Residue 1000mg/kg), Group 3 (Petroleum ether 1000mg/kg), Group 4 (Ethyl acetate 1000mg/kg), Group 5 (Flavonoid 500mg/kg), Group 6 (Flavonoid 1000mg/kg), Group 7 (Positive control, uninfected, untreated), Group 8 (Negative control, infected untreated) and Group 9 (Infected and treated with Berenil®. The body weights of all the animals were determined at pre and post treatment. Both qualitative and quantitative phytochemical analysis of the crude plant extract was also carried out. The in vivo results showed that the flavonoid extract gave the highest prolongation of life by 9 days when compared to its crude counterparts by 6 days at 1000 mg/kg body weight (P<0.05). All the treated animals suffered less weight lost as compared to the infected untreated control. Phytochemical screening of the extract revealed the presence of flavonoid, alkaloid, tannins, glycosides, terpenes, and phenols with Tannins quantitatively being the highest followed by flavonoids. Consequently, flavonoid from B. coriacea is an antitrypanosomal potential and could further be exploited for drug development in the management of African trypanosomiasis.
Context
Forest cover change analyses have revealed net forest gain in many tropical regions. While most analyses have focused solely on forest cover, trees outside forests are vital components of landscape integrity. Quantifying regional-scale patterns of tree cover change, including non-forest trees, could benefit forest and landscape restoration (FLR) efforts.
Objectives
We analyzed tree cover change in Southwestern Panama to quantify: (1) patterns of change from 1998 to 2014, (2) differences in rates of change between forest and non-forest classes, and (3) the relative importance of social-ecological predictors of tree cover change between classes.
Methods
We digitized tree cover classes, including dispersed trees, live fences, riparian forest, and forest, in very high resolution images from 1998 to 2014. We then applied hurdle models to relate social-ecological predictors to the probability and amount of tree cover gain.
Results
All tree cover classes increased in extent, but gains were highly variable between classes. Non-forest tree cover accounted for 21% of tree cover gains, while riparian trees constituted 31% of forest cover gains. Drivers of tree cover change varied widely between classes, with opposite impacts of some social-ecological predictors on non-forest and forest cover.
Conclusions
We demonstrate that key drivers of forest cover change, including topography, road distance and historical forest cover, do not explain rates of non-forest tree cover change. Consequently, predictions from medium-resolution forest cover change analyses may not apply to finer-scale patterns of tree cover. We highlight the opportunity for FLR projects to target tree cover classes adapted to local social and ecological conditions.
Genetic resources have to be managed appropriately to mitigate the impact of climate change. For many wildland plants, conservation will require knowledge of the climatic factors affecting intraspecific genetic variation to minimize maladaptation. Knowledge of the interaction between traits and climate can focus management resources on vulnerable populations, provide guidance for seed transfer and enhance fitness and resilience under changing climates. In this study, traits of big sagebrush (Artemisia tridentata) were examined among common gardens located in different climates. We focus on two subspecies, wyomingensis and tridentata, that occupy the most imperiled warm‐dry spectrum of the sagebrush biome. Populations collected across the sagebrush biome were recorded for flower phenology and survival. Mixed‐effects models examined each trait to evaluate genetic variation, environmental effects, and adaptive breadth of populations. Climate variables derived from population source locations were significantly associated with these traits (P < 0.0001), explaining 31% and 11% of the flower phenology and survival variation, respectively. To illustrate our model and assess variability in prediction, we examine fixed and focal point seed transfer approaches to map contemporary and climate model ensemble projections in two different regions of the sagebrush biome. A comparison of seed transfer areas predicts that populations from warmer climates become more prevalent, replacing colder‐adapted populations by mid‐century. However, these warm‐adapted populations are often located along the trailing edge, margins of the species range predicted to be lost due to a contraction of the climatic niche. Management efforts should focus on the collection and conservation of vulnerable populations and prudent seed transfer to colder regions where these populations are projected to occur by mid‐century. Our models provide the foundation to develop an empirical, climate‐based seed transfer system for current and future restoration of big sagebrush. This article is protected by copyright. All rights reserved.
Restoration and rehabilitation of native vegetation in dryland ecosystems, which encompass over 40% of terrestrial ecosystems, is a common challenge that continues to grow as wildfire and biological invasions transform dryland plant communities. The difficulty in part stems from low and variable precipitation, combined with limited understanding about how weather conditions influence restoration outcomes, and increasing recognition that one‐time seeding approaches can fail if they do not occur during appropriate plant establishment conditions. The sagebrush biome, which once covered over 620,000 km² of western North America, is a prime example of a pressing dryland restoration challenge for which restoration success has been variable. We analyzed field data on Artemisia tridentata (big sagebrush) restoration collected at 771 plots in 177 wildfire sites across its western range, and used process‐based ecohydrological modeling to identify factors leading to its establishment. Our results indicate big sagebrush occurrence is most strongly associated with relatively cool temperatures and wet soils in the first spring after seeding. In particular, the amount of winter snowpack, but not total precipitation, helped explain the availability of spring soil moisture and restoration success. We also find considerable inter‐annual variability in the probability of sagebrush establishment. Adaptive management strategies that target seeding during cool, wet years or mitigate effects of variability through repeated seeding may improve the likelihood of successful restoration in dryland ecosystems. Given consistent projections of increasing temperatures, declining snowpack, and increasing weather variability throughout mid‐latitude drylands, weather‐centric adaptive management approaches to restoration will be increasingly important for dryland restoration success.
This article is protected by copyright. All rights reserved.
Several recent meta-analyses have aimed to determine whether natural regeneration is more effective at recovering tropical forests than active restoration (for example, tree planting). We reviewed this literature and found that comparisons between strategies are biased by positive site selection. Studies of natural forest regeneration are generally conducted at sites where a secondary forest was already present, whereas tree planting studies are done in a broad range of site conditions, including non-forested sites that may not have regenerated in the absence of planting. Thus, a level of success in forest regeneration is guaranteed for many studies representing natural regeneration, but not for those representing active restoration. The complexity of optimizing forest restoration is best addressed by paired experimentation at the same site, replicated across landscapes. Studies that have taken this approach reach different conclusions than those arising from meta-analyses; the results of paired experimental comparisons emphasize that natural regeneration is a highly variable process and that active restoration and natural regeneration are complementary strategies.
Interactions between fire and nonnative, annual plant species (that is, “the grass/fire cycle”) represent one of the greatest threats to sagebrush (Artemisia spp.) ecosystems and associated wildlife, including the greater sage-grouse (Centrocercus urophasianus). In 2015, U.S. Department of the Interior called for a “science-based strategy to reduce the threat of large-scale rangeland fire to habitat for the greater sage-grouse and the sagebrush-steppe ecosystem.” An associated guidance document, the “Integrated Rangeland Fire Management Strategy Actionable Science Plan,” identified fuel breaks as high priority areas for scientific research. Fuel breaks are intended to reduce fire size and frequency, and potentially they can compartmentalize wildfire spatial distribution in a landscape. Fuel breaks are designed to reduce flame length, fireline intensity, and rates of fire spread in order to enhance firefighter access, improve response times, and provide safe and strategic anchor points for wildland fire-fighting activities. To accomplish these objectives, fuel breaks disrupt fuel continuity, reduce fuel accumulation, and (or) increase plants with high moisture content through the removal or modification of vegetation in strategically placed strips or blocks of land.
Fuel breaks are being newly constructed, enhanced, or proposed across large areas of the Great Basin to reduce wildfire risk and to protect remaining sagebrush ecosystems (including greater sage-grouse habitat). These projects are likely to result in thousands of linear miles of fuel breaks that will have direct ecological effects across hundreds of thousands of acres through habitat loss and conversion. These projects may also affect millions of acres indirectly because of edge effects and habitat fragmentation created by networks of fuel breaks. Hence, land managers are often faced with a potentially paradoxical situation: the need to substantially alter sagebrush habitats with fuel breaks to ultimately reduce a greater threat of their destruction from wildfire. However, there is relatively little published science that directly addresses the ability of fuel breaks to influence fire behavior in dryland landscapes or that addresses the potential ecological effects of the construction and maintenance of fuel breaks on sagebrush ecosystems and associated wildlife species.
This report is intended to provide an initial assessment of both the potential effectiveness of fuel breaks and their ecological costs and benefits. To provide this assessment, we examined prior studies on fuel breaks and other scientific evidence to address three crucial questions: (1) How effective are fuel breaks in reducing or slowing the spread of wildfire in arid and semi-arid shrubland ecosystems? (2) How do fuel breaks affect sagebrush plant communities? (3) What are the effects of fuel breaks on the greater sage-grouse, other sagebrush obligates, and sagebrush-associated wildlife species? We also provide an overview of recent federal policies and management directives aimed at protecting remaining sagebrush and greater sage-grouse habitat; describe the fuel conditions, fire behavior, and fire trends in the Great Basin; and suggest how scientific inquiry and management actions can improve our understanding of fuel breaks and their effects in sagebrush landscapes.
En México, las acciones encaminadas a la recuperación de las condiciones, procesos y funciones de los ecosistemas que han sido degradados (i.e., restauración ecológica) necesitan ser documentadas de forma sistemática. Así, el propósito del presente estudio fue caracterizar de manera retrospectiva, los enfoques y estrategias relacionadas con la restauración de ecosistemas terrestres en México y resaltar sus éxitos y las lecciones aprendidas. El trabajo también permitió realizar un análisis de la situación actual de las actividades de restauración y vislumbrar las tendencias a futuro en su dimensión biofísica, social, financiera e institucional. De manera más amplia, este análisis buscó contribuir con elementos para impulsar, fortalecer y guiar los esfuerzos de restauración ecológica en México. Este estudio además se suma a los esfuerzos recientes desarrollados en países como Colombia y Brasil, para contribuir al desarrollo futuro de la restauración ecológica y con ello, mejorar y fortalecer sus capacidades técnicas y científicas en Latinoamérica. Esta evaluación se torna muy necesaria en el contexto de los compromisos internacionales sobre restauración ecológica de los cuales México forma parte, tales como la Meta Aichi 15 del Convenio de Diversidad Biológica, el Desafío de Bonn y la Iniciativa 20x20 para América Latina. A la fecha, México cuenta con importantes instrumentos que incluyen a la restauración en sus objetivos, como el Programa Nacional Forestal. El presente análisis representa un insumo fundamental para la elaboración de un Plan Nacional de Restauración Ecológica que enmarque todas las estrategias e iniciativas existentes y que sea acorde con la situación actual de las actividades y las tendencias reconocidas en la materia.
Este estudio abarcó ecosistemas terrestres incluyendo los bosques templados y tropicales, humedales, manglares y ecosistemas ribereños. Los proyectos de restauración se identificaron mediante una búsqueda exhaustiva utilizando sistemas informáticos para la identificación de archivos almacenados en servidores web y bases de datos disponibles en línea. La identificación de las iniciativas se complementó con la consulta a personas e instituciones académicas, gubernamentales y no gubernamentales. La recopilación de la información de los proyectos se realizó de manera sistemática: se enviaron encuestas digitales y además se capturó la información de los proyectos previamente identificados en formatos de acopio. El formulario, que fue elaborado en un taller con actores claves del gobierno, la academia y la sociedad civil, contenía preguntas sobre los aspectos de planeación, ejecución, divulgación y monitoreo de las iniciativas de restauración existentes en México. La información adquirida provino de 75 proyectos establecidos desde 1979.
El análisis de los resultados mostró que la mayoría de las acciones de restauración se iniciaron a partir del año 2004 con un promedio de 5.5 proyectos por año hasta el 2015. El 57 % de los proyectos aún estaba activo cuando se realizó la encuesta: la mayoría de los proyectos activos se encontraba en fase de monitoreo (el 36 %). Solo el 15% de los proyectos tuvieron una antigüedad mayor a los 12 años. El área de los proyectos evaluados sumó 1,556,839.01 ha y el 91.9% de los proyectos se establecieron entre el 2004 y el 2016. El 67 % de los proyectos evaluados tenían áreas menores o iguales a las 1,000 ha. En promedio, cada proyecto abarcó 94.3 ha; sin embargo, la variación en el área por proyecto fue muy grande (desviación estándar: 201.9 ha). Tres proyectos de >200,000 ha (419,000 ± 232,277.85) fueron iniciados por CONANP (en el 2010), por CONAFOR (2013) y por Conservación Internacional (2013). De acuerdo a la regionalización por afinidades geográficas, la mayoría de los proyectos se ubicó en tres divisiones florísticas: la Sierra Madre Oriental, la Costa del Golfo de México y la Planicie Costera del Noreste. El análisis de los proyectos de restauración por categoría de elevación reveló que la mayoría de los proyectos operados por CONAFOR han sido establecidos en áreas entre los 1,000 y 3,000 m de elevación y el análisis por ecorregiones mostró que estas elevaciones corresponden a bosque templado. Los proyectos operados por otras instituciones se han desarrollado en su mayoría en áreas con una elevación menor a los 200 m s.n.m. en la ecorregión llamada Selvas Cálido-Secas. El análisis de los proyectos de restauración por provincias de humedad y formaciones vegetales reveló que para CONAFOR, la formación vegetal con el mayor porcentaje de proyectos fue el Bosque Seco Montano Bajo (24 %) de la provincia “seca”; la formación vegetal con el mayor porcentaje de proyectos en la provincia “húmeda” fue el Bosque Subhúmedo Premontano (12 %). De los proyectos realizados por otras instituciones, la formación vegetal con el mayor porcentaje de proyectos fue el Bosque Seco Premontano (30 %) en la provincia “seca” y destaca el porcentaje de proyectos en la provincia “muy seca” (7 %). El análisis por ecorregiones, afinidades geográficas y provincias de humedad mostró que las áreas atendidas por CONAFOR se complementan con aquellas que han sido atendidas por otras instituciones.
El agente de degradación identificado más frecuentemente en los predios intervenidos fue la ganadería extensiva (53%) mientras que el uso de suelo previo a la intervención más identificado fue también la ganadería (47%). El 47 % de los proyectos de restauración ecológica evaluados se establecieron en áreas de propiedad comunal o ejidal, el 31 % en terrenos federales y el 23 % en terrenos privados. El 51 % de los proyectos se estableció dentro de Áreas Naturales Protegidas.
El costo global de todos los proyectos evaluados en este estudio ascendió a US$298,001,715 dólares; el 52 % de los proyectos obtuvo financiamiento de una sola fuente. La fuente de financiamiento más mencionada fue el gobierno (98.5%) y la mayor inversión se realizó en terrenos ejidales o comunales (47 %). El área intervenida explicó en un 27% los montos de inversión necesarios para realizar el proyecto de restauración ecológica. Los tipos de vegetación más costosos para restaurar fueron la Selva Seca que tuvo el mayor monto de inversión por hectárea por año y los Humedales que registraron la mayor inversión total; además, la Selva Seca presentó el menor número de proyectos y la menor inversión total (4.4%).
El análisis del grado de participación de los diferentes actores en los proyectos de restauración reveló que las instituciones de gobierno destacaron como promotoras (52%) y financiadoras (73 %) mientras que las instituciones académicas fueron más frecuentemente mencionadas como diseñadoras (45%) y responsables técnicos (45 %). El análisis del grado de participación dependiendo de la tenencia de la tierra reveló que los ejidatarios o comuneros destacaron como ejecutores (25 %) y promotores (21%) mientras que la iniciativa privada, individuos o empresas destacaron como financiadores (15%). En el 86% de los proyectos, los miembros de la comunidad en general participaron en las acciones de restauración, mientras que en el 62 % de los proyectos hubo participación de las mujeres; la población vulnerable participó en el 33 % de los proyectos. Los miembros de la comunidad en general participaron principalmente en la ejecución de las acciones de restauración (78%), y en el desarrollo e implementación de los proyectos piloto (53.7%); sólo en un 28% de los proyectos, los miembros de la comunidad participaron en la fase de diagnóstico. Las mujeres y la población vulnerable participaron en mayor medida en la ejecución de las acciones de restauración (49% y 22% respectivamente). El conocimiento tradicional se contempló en las acciones de restauración del 39% de los proyectos; este se incluyó en el 75% de los proyectos, en la ejecución de las acciones.
El análisis de los objetivos y metas de los proyectos evaluados reveló que el 65 % de los proyectos planteó uno o dos objetivos. En el 53 % de los proyectos se estableció como meta la recuperación del hábitat y su conectividad para especies en peligro de extinción; en el 81 % de los proyectos se buscó la recuperación de las plantas, y en segundo lugar se buscó recuperar las aves (43%). El análisis de las metas relacionadas a la recuperación de servicios ecosistémicos reveló que en el 85% de los proyectos se buscó la recuperación de servicios de regulación como regulación climática, de enfermedades, hídrica, asociada a la biodiversidad, de la erosión del suelo, purificación del agua, o polinización. El análisis de las metas socio-económicas que incluía la rehabilitación ambiental, la productividad silvopastoril y otros procesos socio-económicos reveló que en el 86% de los proyectos se buscó la generación de empleos, el 38 % de los proyectos se establecieron debido a un mandato de gobierno mientras que en el 30 % de los proyectos se buscó promover la biodiversidad en sistemas silvopastoriles mediante el enriquecimiento con especies nativas.
El análisis de las evaluaciones que se realizaron al inicio del proyecto (línea base) reveló que en el 36% de los proyectos se midieron una o más variables de recuperación natural; la variable más mencionada fue la evaluación de las condiciones ambientales adecuadas para el crecimiento de las plantas, como la temperatura y humedad (28 %). En el 52% de los proyectos se priorizó los sitios a restaurar basándose en criterios biofísicos y socio-económicos; en 45 % de los proyectos se mencionó a la recuperación de la cubierta forestal como el criterio de priorización. Sólo en el 17 % de los proyectos se planeó la recuperación del ecosistema intervenido en el contexto del cambio climático mientras que en el 33 % de los proyectos se consideró que las acciones de restauración planteadas reducirían la vulnerabilidad al cambio climático. Se consideró que los principales beneficios de las acciones de restauración fueron en términos de servicios ambientales, fauna, recursos naturales y biodiversidad. Se consideró que las comunidades eran los beneficiarios inmediatos de las acciones de restauración a través de los beneficios ecológicos o de apoyos económicos para la realización de las acciones de restauración.
El análisis de los enfoques espaciales reveló que en el 63 % de los proyectos se adoptó un enfoque de paisaje, en el 56 % un enfoque de cuenca y en el 45 % un enfoque de ecosistema mientras que en el 47% de los proyectos se consideró la conectividad espacial. Además, en el 80% de los proyectos se identificó el ecosistema de referencia: en el 59% de los proyectos se usaron los remanentes de vegetación en el paisaje adyacente como ecosistema de referencia. En el 52 % de los proyectos se estableció una línea base del sitio a restaurar utilizando variables de tipo abiótico, biótico, fisiográfico o social, siendo las variables bióticas, utilizadas para el establecimiento de la línea base en el 43% de los proyectos. En el 28 % de los proyectos se tomaron en cuenta los atributos de un ecosistema restaurado establecidos por la Sociedad de Restauración Ecológica Internacional (SER 2002; Clewell et al. 2004). El 80% de los proyectos reportó haber elaborado un calendario de actividades donde se incluyeron los plazos de ejecución, evaluación y seguimiento.
El análisis de los aspectos técnicos de la ejecución de los proyectos reveló que en el 84 % de los proyectos se controlaron los factores de perturbación. Las técnicas más usadas para el restablecimiento de la flora terrestre fueron favorecer la regeneración natural (58%) y la plantación de especies con atributos ecológicos específicos (56%). La técnica más usada para el restablecimiento de la fauna nativa fue el establecimiento de estructuras para facilitar la colonización de fauna. Los proyectos utilizaron con mayor frecuencia técnicas desarrolladas por ellos mismos para el proyecto en cuestión (73.3%) o de proyectos anteriores (33 %). En el 87.5% de los proyectos se seleccionó el material biológico tomando en cuenta que las especies fueran conocidas como residentes originales de la zona, ya sea nativas o naturalizadas y en el 48 % de los proyectos, los ejecutores propagaron el material biológico que utilizaron.
El análisis de los aspectos técnicos de los resultados reveló que en el 35% de los proyectos, los encuestados aseguraron haber alcanzado entre el 75 y 100 % de los objetivos planteados. En el 20 % de los proyectos se consideró que la recuperación de la biodiversidad había avanzado entre 1 y 25 % con respecto a las condiciones iniciales; en el 54 % se consideró que la recuperación de los servicios ecosistémicos de provisión había avanzado entre 1 y 25 % con respecto a las condiciones iniciales mientras que en el 45 % de los proyectos se consideró que la recuperación de los servicios de regulación había avanzado entre 25 y 50 % con respecto a las condiciones iniciales. Finalmente, en el 47 % de los proyectos se consideró que la recuperación de los servicios culturales había avanzado entre 50 y 75 % con respecto a las condiciones iniciales.
El análisis de la percepción de los involucrados en los proyectos de restauración reveló que en el 51% de los proyectos se consideró que la colaboración mejoró entre las organizaciones, en el 64% de los proyectos se consideró que mejoró la colaboración entre los individuos y en el 49 % de los proyectos que mejoro la colaboración entre las instituciones. En promedio se produjeron 3.3 ± 3.7 publicaciones internacionales y 2.8 ± 3.6 publicaciones nacionales. En números absolutos, el material de difusión como libros técnicos, capítulos de libro, manuales, informes técnicos o tesis fueron las publicaciones más frecuentes (67 productos); el 66 % de los proyectos generaron este tipo de productos. También, en promedio se hicieron 6.2 ± 12.6 presentaciones en congresos y 11 ±32.8 presentaciones para el público en general; en total 221 presentaciones fueron realizadas por sólo el 9 % de los proyectos. Finalmente, para el 87% de los proyectos se realizó reuniones con las comunidades para informarles los objetivos del proyecto (76%), los avances (81%), los resultados principales (78%) o se generó material audiovisual para la divulgación de las acciones de restauración (34%). El medio de comunicación utilizado con mayor frecuencia para la divulgación de las acciones de restauración fue el periódico (28%)
El análisis de los aspectos técnicos del monitoreo reveló que en el 57% de los proyectos se estableció un plan de seguimiento a priori para evaluar los efectos de la intervención¸ en el 31 % de los proyectos se realizaron evaluaciones anuales. En el 88 % de los proyectos se realizaron evaluaciones de monitoreo a corto plazo; las variables más mencionadas en esta categoría fueron la supervivencia, crecimiento y estructura de la vegetación (74% de los proyectos). En el 69% de los proyectos se usó un monitoreo científico para medir el éxito de las acciones de restauración y en el 54 % de los proyectos, el responsable técnico del monitoreo provenía de la academia. Los resultados mostraron que la ejecución de los proyectos enfrenta una serie de retos y oportunidades de carácter biofísico, institucional, social y financiaron. La oportunidad más mencionada fue la de vinculación con instituciones académicas (55 %) mientras que el reto más frecuente fue que los fondos fueron insuficientes (38%).
La información aquí presentada reveló que los proyectos de restauración se beneficiarían con una planeación adecuada que incluyera: (1) las causas de la degradación del ecosistema, su estado inicial, y las zonas prioritarias para la restauración; (2) análisis de costo-beneficios, la incertidumbre económica, los costos de establecimiento y de monitoreo; (3) un plan de monitoreo integral, participativo y que corresponda con los objetivos del proyecto; (4) la divulgación por medios tradicionales, académicos y más actuales como las redes sociales y (5) la planeación de acciones de restauración en el contexto del cambio climático. Estos resultados son un aporte para la construcción del Plan Nacional de Restauración que podrá incluir lineamientos generales para el diseño de estrategias que llenen los vacíos identificados. El Plan Nacional contribuirá a que México cumpla con sus compromisos internacionales en materia de restauración.
Admired for its elaborate breeding displays and treasured as a game bird, the Greater Sage-Grouse is a charismatic symbol of the broad open spaces in western North America. Unfortunately these birds have declined across much of their range — which stretches across eleven western states and reaches into Canada — mostly due to loss of critical sagebrush habitat. Today the Greater Sage-Grouse is at the center of a complex conservation challenge. This multifaceted volume, an important foundation for developing conservation strategies and actions, provides a comprehensive synthesis of scientific information on the biology and ecology of the Greater Sage-Grouse. Bringing together the experience of thirty-eight researchers, it describes the bird's population trends, its sagebrush habitat, and potential limitations to conservation, including the effects of rangeland fire, climate change, invasive plants, disease, and land uses such as energy development, grazing, and agriculture.
Aim
Data on species occurrences are far more common than data on species abundances. However, a central goal of large‐scale ecology is to understand the spatial distribution of abundance. It has been proposed that species distribution models trained on species occurrence records may capture variation in species abundance. Here, we gauge support for relationships between species abundance and predicted climatic suitability from species distribution models, and relate the slope of this relationship to species traits, evolutionary relationships and sampling completeness.
Location
USA.
Time period
1658–2017.
Major taxa studied
Mammal and tree species.
Methods, Results
To explore the generality of abundance–suitability relationships, we trained species distribution models on species occurrence and species abundance data for 246 mammal species and 158 tree species, and related model‐predicted occurrence probabilities to population abundance predictions. Further, we related the resulting abundance–suitability relationship coefficients to species traits, geographic range sizes, evolutionary relationships and the number of occurrence records to investigate a potential trait or sampling basis for abundance–suitability relationship detectability. We found little evidence for consistent abundance–suitability relationships in mammal ( = .045) or tree ( = −.005) species, finding nearly as many negative and positive relationships. These relationships had little explanatory power, and coefficients were unrelated to species traits, range size or evolutionary relationships.
Main conclusions
Our findings suggest that species climatic suitability based on occurrence data may not be reflected in species abundances, suggesting a need to investigate nonclimatic sources of species abundance variation.
Significance
Wildfires have profound impacts on forested ecosystems and rural communities. Increases in area burned by wildfires in the western United States have been widely attributed to reduced winter snowpack or increased summer temperatures. Trends in precipitation have previously been dismissed as has their feedback to regional temperature trends. We show that declines in summer precipitation and wetting rain days have likely been a primary driver of increases in wildfire area burned. Understanding the climatic drivers of fire activity is important for informing forest management. Our findings are consistent with future climate projections, which predict further decreases in summer precipitation and longer dry periods between rain events across much of the West.