Nathalie Pettorelli - Academia.edu (original) (raw)
Papers by Nathalie Pettorelli
Ecosphere, 2018
Although ephemeral rivers act as linear oases and play a fundamental role in sustaining regional ... more Although ephemeral rivers act as linear oases and play a fundamental role in sustaining regional biodiversity in dryland regions, little is known about these systems or their sensitivity to human impacts. Without such knowledge, it is difficult to manage or conserve them. Here, we conduct the first systematic investigation into the determinants of riparian tree distributions along a large ephemeral river. Adopting a macroecological approach, we test four hypotheses relating to the effects of topography, river flow, climate, and land tenure on three indices of tree distribution: species richness, occupancy, and recruitment. We also consider the effect of upstream damming. Our study site is the Swakop River in Namibia. The most common trees along the river were the invasive Prosopis spp., followed by native Faidherbia albida, Vachellia erioloba, Euclea pseudebenus, and Vachellia tortilis. We found a gradient in tree distributions along the river, with a drier climate westward associat...
The Science of the total environment, Jan 14, 2017
The current set of global conservation targets requires methods for monitoring the changing statu... more The current set of global conservation targets requires methods for monitoring the changing status of ecosystems. Protocols for ecosystem risk assessment are uniquely suited to this task, providing objective syntheses of a wide range of data to estimate the likelihood of ecosystem collapse. Satellite remote sensing can deliver ecologically relevant, long-term datasets suitable for analysing changes in ecosystem area, structure and function at temporal and spatial scales relevant to risk assessment protocols. However, there is considerable uncertainty about how to select and effectively utilise remotely sensed variables for risk assessment. Here, we review the use of satellite remote sensing for assessing spatial and functional changes of ecosystems, with the aim of providing guidance on the use of these data in ecosystem risk assessment. We suggest that decisions on the use of satellite remote sensing should be made a priori and deductively with the assistance of conceptual ecosyste...
Remote Sensing in Ecology and Conservation, 2017
Under the snow: a new camera trap opens the white box of subnivean ecology Research 2068 41 2016 ... more Under the snow: a new camera trap opens the white box of subnivean ecology Research 2068 41 2016 From imagery to ecology: leveraging time series of all available Landsat observations to map and monitor ecosystem state and dynamics Research 1763 23 2016 Patterns of twenty-first century forest loss across a global network of important sites for biodiversity Research 1712 104 2015 Testing the water: detecting artificial water points using freely available satellite data and open source software Research 1586 30 2016 Is waveform worth it? A comparison of LiDAR approaches for vegetation and landscape characterization Interdisciplinary perspectives 1563 19 2015 Life-history attributes and resource dynamics determine intraspecific home-range sizes in Carnivora Research 1532 33 2015 High-resolution forest canopy height estimation in an African blue carbon ecosystem Research 1502 46 2016 Wildlife speed cameras: measuring animal travel speed and day range using camera traps Research 1287 27 2016 An invasive-native mammalian species replacement process captured by camera trap survey random encounter models Research 1135 28 2016 Sea turtle nesting patterns in Florida visa -vis satellite-derived measures of artificial lighting Research 1057 84 2016 Remote sensing of species dominance and the value for quantifying ecosystem services Interdisciplinary perspectives 1017 12 2016 Integrating LiDAR-derived tree height and Landsat satellite reflectance to estimate forest regrowth in a tropical agricultural landscape Research 988 48 2016 How do passive infrared triggered camera traps operate and why does it matter? Breaking down common misconceptions Interdisciplinary perspectives 966 14 2016 The higher you go the less you will know: placing camera traps high to avoid theft will affect detection Research 858 33 2016 The role of space agencies in remotely sensed essential biodiversity variables Policy forum 843 18 2016 Observing ecosystems with lightweight, rapid-scanning terrestrial lidar scanners Research 747 11 2016 A simple remote sensing based information system for monitoring sites of conservation importance Interdisciplinary perspectives 616 1 2016 Upland vegetation mapping using Random Forests with optical and radar satellite data Research 449 13 2016 Ultrasonic monitoring to assess the impacts of forest conversion on Solomon Island bats Research 420 19 2016 Earth observation archives for plant conservation: 50 years monitoring of Itigi-Sumbu thicket Research 377 12 54
Science (New York, N.Y.), Mar 31, 2017
Distributions of Earth's species are changing at accelerating rates, increasingly driven by h... more Distributions of Earth's species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation's Sustainable Development Goals.
Proceedings of the National Academy of Sciences of the United States of America, Jan 27, 2016
Establishing and maintaining protected areas (PAs) are key tools for biodiversity conservation. H... more Establishing and maintaining protected areas (PAs) are key tools for biodiversity conservation. However, this approach is insufficient for many species, particularly those that are wide-ranging and sparse. The cheetah Acinonyx jubatus exemplifies such a species and faces extreme challenges to its survival. Here, we show that the global population is estimated at ∼7,100 individuals and confined to 9% of its historical distributional range. However, the majority of current range (77%) occurs outside of PAs, where the species faces multiple threats. Scenario modeling shows that, where growth rates are suppressed outside PAs, extinction rates increase rapidly as the proportion of population protected declines. Sensitivity analysis shows that growth rates within PAs have to be high if they are to compensate for declines outside. Susceptibility of cheetah to rapid decline is evidenced by recent rapid contraction in range, supporting an uplisting of the International Union for the Conserva...
PeerJ, 2016
Ephemeral rivers act as linear oases in drylands providing key resources to people and wildlife. ... more Ephemeral rivers act as linear oases in drylands providing key resources to people and wildlife. However, not much is known about these rivers’ sensitivities to human activities. We investigated the landscape-level determinants of riparian tree dieback along the Swakop River, a dammed ephemeral river in Namibia, focusing on the native ana tree (Faidherbia albida) and the invasive mesquite (Prosopisspp.). We surveyed over 1,900 individual trees distributed across 24 sites along a 250 km stretch of the river. General linear mixed models were used to test five hypotheses relating to three anthropogenic threats: river flow disruption from damming, human settlement and invasive species. We found widespread dieback in both tree populations: 51% mortality in ana tree, with surviving trees exhibiting 18% canopy death (median); and 26% mortality in mesquite, with surviving trees exhibiting 10% canopy death. Dieback in the ana tree was most severe where trees grew on drier stretches of the ri...
Parasites & vectors, Jul 1, 2016
The host represents a heterogeneous ecosystem where multiple parasite species co-occur and intera... more The host represents a heterogeneous ecosystem where multiple parasite species co-occur and interact with each other for space and resources. Although these interactions may rule the features of an infracommunity and may shape the infracommunity response to external perturbations, the resilience of ectoparasite communities to new infestations remains poorly explored. We analysed the composition of the ectoparasite communities found on 214 individual Iberian ibexes (Capra pyrenaica) inhabiting the Sierra Nevada Natural Space, southern Spain. Using classification and regression trees, we explored how the presence of Sarcoptes scabiei (a highly contagious mite), the off-host environment and the host sex govern the prevalence and abundance of lice and ticks. Null model analysis was applied to assess the impact of S. scabiei on the structure of the ectoparasite communities. Our results suggest that S. scabiei infestation acts in tandem with off-host environment and host sex to define the ...
Remote Sensing in Ecology and Conservation, 2016
Although satellite-based variables have for long been expected to be key components to a unified ... more Although satellite-based variables have for long been expected to be key components to a unified and global biodiversity monitoring strategy, a definitive and agreed list of these variables still remains elusive. The growth of interest in biodiversity variables observable from space has been partly underpinned by the development of the essential biodiversity variable (EBV) framework by the Group on Earth Observations-Biodiversity Observation Network, which itself was guided by the process of identifying essential climate variables. This contribution aims to advance the development of a global biodiversity monitoring strategy by updating the previously published definition of EBV, providing a definition of satellite remote sensing (SRS) EBVs and introducing a set of principles that are believed to be necessary if ecologists and space agencies are to agree on a list of EBVs that can be routinely monitored from space. Progress toward the identification of SRS-EBVs will require a clear understanding of what makes a biodiversity variable essential, as well as agreement on who the users of the SRS-EBVs are. Technological and algorithmic developments are rapidly expanding the set of opportunities for SRS in monitoring biodiversity, and so the list of SRS-EBVs is likely to evolve over time. This means that a clear and common platform for data providers, ecologists, environmental managers, policy makers and remote sensing experts to interact and share ideas needs to be identified to support long-term coordinated actions.
Remote Sensing in Ecology and Conservation, 2015
Assessing the level of diversity in plant communities from field-based data is difficult for a nu... more Assessing the level of diversity in plant communities from field-based data is difficult for a number of practical reasons: (1) establishing the number of sampling units to be investigated can be difficult; (2) the choice of sample design can impact on results; and (3) defining the population of concern can be challenging. Satellite remote sensing (SRS) is one of the most cost-effective approaches to identify biodiversity hotspots and predict changes in species composition. This is because, in contrast to field-based methods, it allows for complete spatial coverages of the Earth's surface under study over a short period of time. Furthermore, SRS provides repeated measures, thus making it possible to study temporal changes in biodiversity. Here, we provide a concise review of the potential of satellites to help track changes in plant species diversity, and provide, for the first time, an overview of the potential pitfalls associated with the misuse of satellite imagery to predict species diversity. Our work shows that, while the assessment of alpha-diversity is relatively straightforward, calculation of beta-diversity (variation in species composition between adjacent locations) is challenging, making it difficult to reliably estimate gamma-diversity (total diversity at the landscape or regional level). We conclude that an increased collaboration between the remote sensing and biodiversity communities is needed in order to properly address future challenges and developments.
Remote Sensing in Ecology and Conservation, 2015
Two prominent limitations of species distribution models (SDMs) are spatial biases in existing oc... more Two prominent limitations of species distribution models (SDMs) are spatial biases in existing occurrence data and a lack of spatially explicit predictor variables to fully capture habitat characteristics of species. Can existing and emerging remote sensing technologies meet these challenges and improve future SDMs? We believe so. Novel products derived from multispectral and hyperspectral sensors, as well as future Light Detection and Ranging (LiDAR) and RADAR missions, may play a key role in improving model performance. In this perspective piece, we demonstrate how modern sensors onboard satellites, planes and unmanned aerial vehicles are revolutionizing the way we can detect and monitor both plant and animal species in terrestrial and aquatic ecosystems as well as allowing the emergence of novel predictor variables appropriate for species distribution modeling. We hope this interdisciplinary perspective will motivate ecologists, remote sensing experts and modelers to work togethe...
Remote Sensing in Ecology and Conservation, 2015
Home ranges capture a fundamental aspect of animal ecology, resulting from interactions between m... more Home ranges capture a fundamental aspect of animal ecology, resulting from interactions between metabolic demands and resource availability. Yet, the understanding of their emergence is currently limited by lack of consideration of the covariation between intrinsic and extrinsic drivers. We analysed intraspecific home-range size (HRS) variation with respect to life histories and remotely sensed proxies of resource dynamics for 21 Carnivora species. Our best model explained over half of the observed variability in intraspecific HRS across populations of multiple species. At the species level, median HRS was smaller for omnivorous species and increased with increasing body mass (model R 2 = 0.66). Here, HRS scaled with body mass at 0.80, a value much closer to the expected allometric scaling of 0.75 than previously reported. At the intraspecific level, while much variation was driven by intrinsic factors (body mass, diet, social organization and sex; R 2 = 0.39), inclusion of spatiotemporal variation in extrinsic factors (average resource availability and seasonality) enabled explanation of a further 13% of observed variability in HRS. We found no evidence for interactions between intrinsic and extrinsic HRS drivers, suggesting a generally ubiquitous influence of resource availability on space-use. Our findings illustrate how spatial and temporal information on resource dynamics as derived by satellite data can significantly improve our understanding of HRS variation at the interspecific and intraspecific levels, and urge caution in interpreting HRS allometry in the face of large intraspecific variation. Moreover, our results highlight the importance of considering life-history constraints in modelling intraspecific space-use and HRS.
Bridging the Gap between Global Commitment and Local Action, 2013
Wiley-Blackwell and the Zoological Society of London are proud to present our Conservation Scienc... more Wiley-Blackwell and the Zoological Society of London are proud to present our Conservation Science and Practice series. Each book in the series reviews a key issue in conservation today from a multidisciplinary viewpoint.
International Journal of Ecology, 2009
Understanding what drives variation in the abundance of organisms is fundamental to evolutionary ... more Understanding what drives variation in the abundance of organisms is fundamental to evolutionary ecology and wildlife management. Yet despite its importance, there is still great uncertainty about the main factors influencing variation in vertebrate abundance across taxa. We believe valuable knowledge and increased predictive power could be gained by taking into account both the intrinsic factors of species and the extrinsic factors related to environmental surroundings in the commonly citedRQmodel, which provides a simple conceptual framework valid at both the interspecific and the intraspecific scales. Approaches comparing studies undertaken at different spatial and taxonomic scales could be key to our ability to better predict abundance, and thanks to the increased availability of population size data, global geographic datasets, and improved comparative methods, there might be unprecedented opportunities to (1) gain a greater understanding of vertebrate abundance patterns and (2...
Journal of Applied Ecology, 2015
This article may be used for non-commercial purposes in accordance With Wiley Terms and Condition... more This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving. Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
Remote Sensing in Ecology and Conservation, 2014
PLOS ONE, 2015
Deserts are particularly vulnerable to human impacts and have already suffered a substantial loss... more Deserts are particularly vulnerable to human impacts and have already suffered a substantial loss of biodiversity. In harsh and variable desert environments, large herbivores typically occur at low densities, and their large carnivore predators occur at even lower densities. The continued survival of large carnivores is key to healthy functioning desert ecosystems, and the ability to gather reliable information on these rare low density species, including presence, abundance and density, is critical to their monitoring and management. Here we test camera trap methodologies as a monitoring tool for an extremely rare wide-ranging large felid, the critically endangered Saharan cheetah (Acinonyx jubatus hecki). Two camera trapping surveys were carried out over 2-3 months across a 2,551km 2 grid in the Ti-nhağğen region in the Ahaggar Cultural Park, south central Algeria. A total of 32 records of Saharan cheetah were obtained. We show the behaviour and ecology of the Saharan cheetah is severely constrained by the harsh desert environment, leading them to be more nocturnal, be more wide-ranging, and occur at lower densities relative to cheetah in savannah environments. Density estimates ranged from 0.21-0.55/1,000km 2 , some of the lowest large carnivore densities ever recorded in Africa, and average home range size over 2-3 months was estimated at 1,583km 2. We use our results to predict that, in order to detect presence of cheetah with p>0.95 a survey effort of at least 1,000 camera trap days is required. Our study identifies the Ahaggar Cultural Park as a key area for the conservation of the Saharan cheetah. The Saharan cheetah meets the requirements for a charismatic flagship species that can be used to "market" the Saharan landscape at a sufficiently large scale to help reverse the historical neglect of threatened Saharan ecosystems.
Trends in Ecology & Evolution, 2005
Science, 2013
A global system of harmonized observations is needed to inform scientists and policy-makers.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2014
Deserts are among the most poorly monitored and understood biomes in the world, with evidence sug... more Deserts are among the most poorly monitored and understood biomes in the world, with evidence suggesting that their biodiversity is declining fast. Oil exploration and exploitation can constitute an important threat to fragmented and remnant desert biodiversity, yet little is known about where and how intensively such developments are taking place. This lack of information hinders local efforts to adequately buffer and protect desert wildlife against encroachment from anthropogenic activity. Here, we investigate the use of freely available satellite imagery for the detection of features associated with oil exploration in the African Sahelo-Saharan region. We demonstrate how texture analyses combined with Landsat data can be employed to detect ground-validated exploration sites in Algeria and Niger. Our results show that site detection via supervised image classification and prediction is generally accurate. One surprising outcome of our analyses is the relatively high level of site ...
Ecosphere, 2018
Although ephemeral rivers act as linear oases and play a fundamental role in sustaining regional ... more Although ephemeral rivers act as linear oases and play a fundamental role in sustaining regional biodiversity in dryland regions, little is known about these systems or their sensitivity to human impacts. Without such knowledge, it is difficult to manage or conserve them. Here, we conduct the first systematic investigation into the determinants of riparian tree distributions along a large ephemeral river. Adopting a macroecological approach, we test four hypotheses relating to the effects of topography, river flow, climate, and land tenure on three indices of tree distribution: species richness, occupancy, and recruitment. We also consider the effect of upstream damming. Our study site is the Swakop River in Namibia. The most common trees along the river were the invasive Prosopis spp., followed by native Faidherbia albida, Vachellia erioloba, Euclea pseudebenus, and Vachellia tortilis. We found a gradient in tree distributions along the river, with a drier climate westward associat...
The Science of the total environment, Jan 14, 2017
The current set of global conservation targets requires methods for monitoring the changing statu... more The current set of global conservation targets requires methods for monitoring the changing status of ecosystems. Protocols for ecosystem risk assessment are uniquely suited to this task, providing objective syntheses of a wide range of data to estimate the likelihood of ecosystem collapse. Satellite remote sensing can deliver ecologically relevant, long-term datasets suitable for analysing changes in ecosystem area, structure and function at temporal and spatial scales relevant to risk assessment protocols. However, there is considerable uncertainty about how to select and effectively utilise remotely sensed variables for risk assessment. Here, we review the use of satellite remote sensing for assessing spatial and functional changes of ecosystems, with the aim of providing guidance on the use of these data in ecosystem risk assessment. We suggest that decisions on the use of satellite remote sensing should be made a priori and deductively with the assistance of conceptual ecosyste...
Remote Sensing in Ecology and Conservation, 2017
Under the snow: a new camera trap opens the white box of subnivean ecology Research 2068 41 2016 ... more Under the snow: a new camera trap opens the white box of subnivean ecology Research 2068 41 2016 From imagery to ecology: leveraging time series of all available Landsat observations to map and monitor ecosystem state and dynamics Research 1763 23 2016 Patterns of twenty-first century forest loss across a global network of important sites for biodiversity Research 1712 104 2015 Testing the water: detecting artificial water points using freely available satellite data and open source software Research 1586 30 2016 Is waveform worth it? A comparison of LiDAR approaches for vegetation and landscape characterization Interdisciplinary perspectives 1563 19 2015 Life-history attributes and resource dynamics determine intraspecific home-range sizes in Carnivora Research 1532 33 2015 High-resolution forest canopy height estimation in an African blue carbon ecosystem Research 1502 46 2016 Wildlife speed cameras: measuring animal travel speed and day range using camera traps Research 1287 27 2016 An invasive-native mammalian species replacement process captured by camera trap survey random encounter models Research 1135 28 2016 Sea turtle nesting patterns in Florida visa -vis satellite-derived measures of artificial lighting Research 1057 84 2016 Remote sensing of species dominance and the value for quantifying ecosystem services Interdisciplinary perspectives 1017 12 2016 Integrating LiDAR-derived tree height and Landsat satellite reflectance to estimate forest regrowth in a tropical agricultural landscape Research 988 48 2016 How do passive infrared triggered camera traps operate and why does it matter? Breaking down common misconceptions Interdisciplinary perspectives 966 14 2016 The higher you go the less you will know: placing camera traps high to avoid theft will affect detection Research 858 33 2016 The role of space agencies in remotely sensed essential biodiversity variables Policy forum 843 18 2016 Observing ecosystems with lightweight, rapid-scanning terrestrial lidar scanners Research 747 11 2016 A simple remote sensing based information system for monitoring sites of conservation importance Interdisciplinary perspectives 616 1 2016 Upland vegetation mapping using Random Forests with optical and radar satellite data Research 449 13 2016 Ultrasonic monitoring to assess the impacts of forest conversion on Solomon Island bats Research 420 19 2016 Earth observation archives for plant conservation: 50 years monitoring of Itigi-Sumbu thicket Research 377 12 54
Science (New York, N.Y.), Mar 31, 2017
Distributions of Earth's species are changing at accelerating rates, increasingly driven by h... more Distributions of Earth's species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation's Sustainable Development Goals.
Proceedings of the National Academy of Sciences of the United States of America, Jan 27, 2016
Establishing and maintaining protected areas (PAs) are key tools for biodiversity conservation. H... more Establishing and maintaining protected areas (PAs) are key tools for biodiversity conservation. However, this approach is insufficient for many species, particularly those that are wide-ranging and sparse. The cheetah Acinonyx jubatus exemplifies such a species and faces extreme challenges to its survival. Here, we show that the global population is estimated at ∼7,100 individuals and confined to 9% of its historical distributional range. However, the majority of current range (77%) occurs outside of PAs, where the species faces multiple threats. Scenario modeling shows that, where growth rates are suppressed outside PAs, extinction rates increase rapidly as the proportion of population protected declines. Sensitivity analysis shows that growth rates within PAs have to be high if they are to compensate for declines outside. Susceptibility of cheetah to rapid decline is evidenced by recent rapid contraction in range, supporting an uplisting of the International Union for the Conserva...
PeerJ, 2016
Ephemeral rivers act as linear oases in drylands providing key resources to people and wildlife. ... more Ephemeral rivers act as linear oases in drylands providing key resources to people and wildlife. However, not much is known about these rivers’ sensitivities to human activities. We investigated the landscape-level determinants of riparian tree dieback along the Swakop River, a dammed ephemeral river in Namibia, focusing on the native ana tree (Faidherbia albida) and the invasive mesquite (Prosopisspp.). We surveyed over 1,900 individual trees distributed across 24 sites along a 250 km stretch of the river. General linear mixed models were used to test five hypotheses relating to three anthropogenic threats: river flow disruption from damming, human settlement and invasive species. We found widespread dieback in both tree populations: 51% mortality in ana tree, with surviving trees exhibiting 18% canopy death (median); and 26% mortality in mesquite, with surviving trees exhibiting 10% canopy death. Dieback in the ana tree was most severe where trees grew on drier stretches of the ri...
Parasites & vectors, Jul 1, 2016
The host represents a heterogeneous ecosystem where multiple parasite species co-occur and intera... more The host represents a heterogeneous ecosystem where multiple parasite species co-occur and interact with each other for space and resources. Although these interactions may rule the features of an infracommunity and may shape the infracommunity response to external perturbations, the resilience of ectoparasite communities to new infestations remains poorly explored. We analysed the composition of the ectoparasite communities found on 214 individual Iberian ibexes (Capra pyrenaica) inhabiting the Sierra Nevada Natural Space, southern Spain. Using classification and regression trees, we explored how the presence of Sarcoptes scabiei (a highly contagious mite), the off-host environment and the host sex govern the prevalence and abundance of lice and ticks. Null model analysis was applied to assess the impact of S. scabiei on the structure of the ectoparasite communities. Our results suggest that S. scabiei infestation acts in tandem with off-host environment and host sex to define the ...
Remote Sensing in Ecology and Conservation, 2016
Although satellite-based variables have for long been expected to be key components to a unified ... more Although satellite-based variables have for long been expected to be key components to a unified and global biodiversity monitoring strategy, a definitive and agreed list of these variables still remains elusive. The growth of interest in biodiversity variables observable from space has been partly underpinned by the development of the essential biodiversity variable (EBV) framework by the Group on Earth Observations-Biodiversity Observation Network, which itself was guided by the process of identifying essential climate variables. This contribution aims to advance the development of a global biodiversity monitoring strategy by updating the previously published definition of EBV, providing a definition of satellite remote sensing (SRS) EBVs and introducing a set of principles that are believed to be necessary if ecologists and space agencies are to agree on a list of EBVs that can be routinely monitored from space. Progress toward the identification of SRS-EBVs will require a clear understanding of what makes a biodiversity variable essential, as well as agreement on who the users of the SRS-EBVs are. Technological and algorithmic developments are rapidly expanding the set of opportunities for SRS in monitoring biodiversity, and so the list of SRS-EBVs is likely to evolve over time. This means that a clear and common platform for data providers, ecologists, environmental managers, policy makers and remote sensing experts to interact and share ideas needs to be identified to support long-term coordinated actions.
Remote Sensing in Ecology and Conservation, 2015
Assessing the level of diversity in plant communities from field-based data is difficult for a nu... more Assessing the level of diversity in plant communities from field-based data is difficult for a number of practical reasons: (1) establishing the number of sampling units to be investigated can be difficult; (2) the choice of sample design can impact on results; and (3) defining the population of concern can be challenging. Satellite remote sensing (SRS) is one of the most cost-effective approaches to identify biodiversity hotspots and predict changes in species composition. This is because, in contrast to field-based methods, it allows for complete spatial coverages of the Earth's surface under study over a short period of time. Furthermore, SRS provides repeated measures, thus making it possible to study temporal changes in biodiversity. Here, we provide a concise review of the potential of satellites to help track changes in plant species diversity, and provide, for the first time, an overview of the potential pitfalls associated with the misuse of satellite imagery to predict species diversity. Our work shows that, while the assessment of alpha-diversity is relatively straightforward, calculation of beta-diversity (variation in species composition between adjacent locations) is challenging, making it difficult to reliably estimate gamma-diversity (total diversity at the landscape or regional level). We conclude that an increased collaboration between the remote sensing and biodiversity communities is needed in order to properly address future challenges and developments.
Remote Sensing in Ecology and Conservation, 2015
Two prominent limitations of species distribution models (SDMs) are spatial biases in existing oc... more Two prominent limitations of species distribution models (SDMs) are spatial biases in existing occurrence data and a lack of spatially explicit predictor variables to fully capture habitat characteristics of species. Can existing and emerging remote sensing technologies meet these challenges and improve future SDMs? We believe so. Novel products derived from multispectral and hyperspectral sensors, as well as future Light Detection and Ranging (LiDAR) and RADAR missions, may play a key role in improving model performance. In this perspective piece, we demonstrate how modern sensors onboard satellites, planes and unmanned aerial vehicles are revolutionizing the way we can detect and monitor both plant and animal species in terrestrial and aquatic ecosystems as well as allowing the emergence of novel predictor variables appropriate for species distribution modeling. We hope this interdisciplinary perspective will motivate ecologists, remote sensing experts and modelers to work togethe...
Remote Sensing in Ecology and Conservation, 2015
Home ranges capture a fundamental aspect of animal ecology, resulting from interactions between m... more Home ranges capture a fundamental aspect of animal ecology, resulting from interactions between metabolic demands and resource availability. Yet, the understanding of their emergence is currently limited by lack of consideration of the covariation between intrinsic and extrinsic drivers. We analysed intraspecific home-range size (HRS) variation with respect to life histories and remotely sensed proxies of resource dynamics for 21 Carnivora species. Our best model explained over half of the observed variability in intraspecific HRS across populations of multiple species. At the species level, median HRS was smaller for omnivorous species and increased with increasing body mass (model R 2 = 0.66). Here, HRS scaled with body mass at 0.80, a value much closer to the expected allometric scaling of 0.75 than previously reported. At the intraspecific level, while much variation was driven by intrinsic factors (body mass, diet, social organization and sex; R 2 = 0.39), inclusion of spatiotemporal variation in extrinsic factors (average resource availability and seasonality) enabled explanation of a further 13% of observed variability in HRS. We found no evidence for interactions between intrinsic and extrinsic HRS drivers, suggesting a generally ubiquitous influence of resource availability on space-use. Our findings illustrate how spatial and temporal information on resource dynamics as derived by satellite data can significantly improve our understanding of HRS variation at the interspecific and intraspecific levels, and urge caution in interpreting HRS allometry in the face of large intraspecific variation. Moreover, our results highlight the importance of considering life-history constraints in modelling intraspecific space-use and HRS.
Bridging the Gap between Global Commitment and Local Action, 2013
Wiley-Blackwell and the Zoological Society of London are proud to present our Conservation Scienc... more Wiley-Blackwell and the Zoological Society of London are proud to present our Conservation Science and Practice series. Each book in the series reviews a key issue in conservation today from a multidisciplinary viewpoint.
International Journal of Ecology, 2009
Understanding what drives variation in the abundance of organisms is fundamental to evolutionary ... more Understanding what drives variation in the abundance of organisms is fundamental to evolutionary ecology and wildlife management. Yet despite its importance, there is still great uncertainty about the main factors influencing variation in vertebrate abundance across taxa. We believe valuable knowledge and increased predictive power could be gained by taking into account both the intrinsic factors of species and the extrinsic factors related to environmental surroundings in the commonly citedRQmodel, which provides a simple conceptual framework valid at both the interspecific and the intraspecific scales. Approaches comparing studies undertaken at different spatial and taxonomic scales could be key to our ability to better predict abundance, and thanks to the increased availability of population size data, global geographic datasets, and improved comparative methods, there might be unprecedented opportunities to (1) gain a greater understanding of vertebrate abundance patterns and (2...
Journal of Applied Ecology, 2015
This article may be used for non-commercial purposes in accordance With Wiley Terms and Condition... more This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving. Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.
Remote Sensing in Ecology and Conservation, 2014
PLOS ONE, 2015
Deserts are particularly vulnerable to human impacts and have already suffered a substantial loss... more Deserts are particularly vulnerable to human impacts and have already suffered a substantial loss of biodiversity. In harsh and variable desert environments, large herbivores typically occur at low densities, and their large carnivore predators occur at even lower densities. The continued survival of large carnivores is key to healthy functioning desert ecosystems, and the ability to gather reliable information on these rare low density species, including presence, abundance and density, is critical to their monitoring and management. Here we test camera trap methodologies as a monitoring tool for an extremely rare wide-ranging large felid, the critically endangered Saharan cheetah (Acinonyx jubatus hecki). Two camera trapping surveys were carried out over 2-3 months across a 2,551km 2 grid in the Ti-nhağğen region in the Ahaggar Cultural Park, south central Algeria. A total of 32 records of Saharan cheetah were obtained. We show the behaviour and ecology of the Saharan cheetah is severely constrained by the harsh desert environment, leading them to be more nocturnal, be more wide-ranging, and occur at lower densities relative to cheetah in savannah environments. Density estimates ranged from 0.21-0.55/1,000km 2 , some of the lowest large carnivore densities ever recorded in Africa, and average home range size over 2-3 months was estimated at 1,583km 2. We use our results to predict that, in order to detect presence of cheetah with p>0.95 a survey effort of at least 1,000 camera trap days is required. Our study identifies the Ahaggar Cultural Park as a key area for the conservation of the Saharan cheetah. The Saharan cheetah meets the requirements for a charismatic flagship species that can be used to "market" the Saharan landscape at a sufficiently large scale to help reverse the historical neglect of threatened Saharan ecosystems.
Trends in Ecology & Evolution, 2005
Science, 2013
A global system of harmonized observations is needed to inform scientists and policy-makers.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2014
Deserts are among the most poorly monitored and understood biomes in the world, with evidence sug... more Deserts are among the most poorly monitored and understood biomes in the world, with evidence suggesting that their biodiversity is declining fast. Oil exploration and exploitation can constitute an important threat to fragmented and remnant desert biodiversity, yet little is known about where and how intensively such developments are taking place. This lack of information hinders local efforts to adequately buffer and protect desert wildlife against encroachment from anthropogenic activity. Here, we investigate the use of freely available satellite imagery for the detection of features associated with oil exploration in the African Sahelo-Saharan region. We demonstrate how texture analyses combined with Landsat data can be employed to detect ground-validated exploration sites in Algeria and Niger. Our results show that site detection via supervised image classification and prediction is generally accurate. One surprising outcome of our analyses is the relatively high level of site ...