Define Conservation Priorities Research Articles

Combining extinction probability and functional or phylogenetic distinctiveness to define conservation priorities

Given the current accelerating extinction rates, an increasing number of species-based conservation strategies have emerged because of the public interest in helping save particular species by funding rescue actions. Although public interest has focused mainly on well-studied, charismatic species, conservation scientists have developed tools to help prioritize species conservation from a more objective perspective, preserving ecosystem functioning and human well-being for future generations. For that purpose, species-centered biodiversity indicators that account not only for the extinction risk of a species but also for its evolutionary and/or functional distinctiveness have been developed. A species is considered irreplaceable and distinctive if it is isolated on the phylogenetic tree and/or if it has distinct traits, especially functional traits that determine the species' effects on ecosystems. The quantitative values representing extinction risk and distinctiveness of species have often been multiplied to define a quantitative conservation priority score. However, there is a plethora of ways to combine several conservation criteria into a single quantitative priority score, and the product of this multiplication is one such possibility. Each possible way of combining extinction risk and distinctiveness provides a different point of view on which of these should prevail to set conservation priorities. We set up an axiomatic framework on how a species' distinctiveness could be combined with its extinction risk via a tool used to define conservation priorities. By doing so, we show that further work is still needed to better communicate biodiversity indicators to the public and ensure an informed choice of indicators.

Defining Conservation Priorities for Oak Forests in Central Mexico Based on Networks of Connectivity

Connectivity is a landscape property that promotes gene flow between organisms located in different patches of habitat and provides a way to reduce habitat loss by maintaining flux of organisms through the landscape; it is an important factor for conservation decisions. In this study, we evaluated the structural and functional connectivity among 510 oak forest remnants in a basin in central Mexico by modeling the potential distribution of seven oak species that inhabit in it. The structural and functional connectivity of oak forest remnants was estimated by graph theory. Distribution models for all the oak species had a good level of predictability, showing that 53.16% of the basin is suitable for oaks. The importance for connectivity varied between the remnant forests. Large forest fragments had the highest values of connectivity, and small forest fragments acted as steppingstones favoring the movement of organisms among fragments. In the southern region of the basin, connected remnant forests had conformed to a large network, but in the northern region, the remnant forests were mostly isolated. Conservation of oak forests in this basin requires protection for remaining patches by preserving both large and small ones and restoring biological corridors to reduce the isolation of forest fragments.

Understanding top-down and bottom-up processes in an ungulate community to define conservation priorities in a desert environment

Understanding top-down and bottom-up processes in an ungulate community to define conservation priorities in a desert environment

Spatial and Temporal Trends of Burnt Area in Angola: Implications for Natural Vegetation and Protected Area Management

Fire is a key driver of natural ecosystems in Africa. However, human activity and climate change have altered fire frequency and severity, with negative consequences for biodiversity conservation. Angola ranks among the countries with the highest fire activity in sub-Saharan Africa. In this study, we investigated the spatial and temporal trends of the annual burnt area in Angola, from 2001 to 2019, and their association with terrestrial ecoregions, land cover, and protected areas. Based on satellite imagery, we analyzed the presence of significant trends in burnt area, applying the contextual Mann–Kendall test and the Theil–Sen slope estimator. Data on burnt areas were obtained from the moderate-resolution imaging spectroradiometer (MODIS) burnt area product and the analyses were processed in TerrSet. Our results showed that ca. 30% of the country’s area burned every year. The highest percentage of annual burnt area was found in northeast and southeast Angola, which showed large clusters of decreasing trends of burnt area. The clusters of increasing trends were found mainly in central Angola, associated with savannas and grasslands of Angolan Miombo woodlands. The protected areas of Cameia, Luengue-Luiana, and Mavinga exhibited large areas of decreasing trends of burnt area. Conversely, 23% of the Bicuar National Park was included in clusters of increasing trends. Distinct patterns of land cover were found in areas of significant trends, where the clusters of increasing trends showed a higher fraction of forest cover (80%) than the clusters of decreasing trends (55%). The documentation of burnt area trends was very important in tropical regions, since it helped define conservation priorities and management strategies, allowing more effective management of forests and fires in countries with few human and financial resources.

Development of a prioritised checklist of crop wild relatives for conservation in Malawi

The national increase in human population in Sub-Saharan Africa (SSA) demands for more food; while increase in the impact of climate change, demands for resilient agricultural production systems, and both call for improved agricultural productivity. Plant breeders will need adaptive traits to improve crop productivity and resilience. Crop wild relatives (CWR) have the potential to offer the much needed diversity for crop improvement, but their diversity is inadequately conserved. Lack of knowledge about their occurrence in Malawi, limits their systematic conservation and utilisation. Developing a CWR national inventory helps to define conservation priorities and actions. The objective of this study was to match checklists of crop genera and national flora, using their taxonomic and genetic relatedness information. This resulted into the first comprehensive annotated checklist of 446 CWR taxa in Malawi, which was prioritised by a set of criteria previously agreed with national stakeholders based on socio-economic importance of the related crop, potential use of the wild relative in crop improvement and threat status. The inventory comprises of 277 CWR taxa, identified as priority for conservation in Malawi; of which 78% were native. These belong to 56 genera and are related to 54 food, fodder, spices and beverage crops; and include taxa related to crops of regional and global importance. Eighty-seven taxa of highest priority for conservation were further identified, 12.6% of which have confirmed uses in crop improvement on pests and disease resistance, drought tolerance and yielding ability. The inventory will facilitate effective conservation and availability of these taxa for their use in crop improvement.
 Key words: Annotated checklist, national inventory, systematic conservation

Over-winter ecology and relative density of Canada Warbler Cardellina canadensis in Colombia: the basis for defining conservation priorities for a sharply declining long-distance migrant – CORRIGENDUM

Over-winter ecology and relative density of Canada Warbler Cardellina canadensis in Colombia: the basis for defining conservation priorities for a sharply declining long-distance migrant – CORRIGENDUM - Volume 31 Issue 1

<p><strong>The endemic and range restricted vascular plants of Croatia: diversity, distribution patterns and their conservation status</strong></p>

The Balkan Peninsula is recognized as an important centre of native and endemic plant species diversity as well as an important wildlife refuge area. However, although Croatia hosts more than half of plant species found on the Balkan Peninsula, the endemic taxa have never been evaluated or used to define conservation priorities. We analyzed the qualitative composition of the endemic and range restricted species, their spatial distribution, centres of endemism, and conservation status (non-IUCN). We generated an updated and annotated checklist of 349 endemic or range-restricted plant taxa (6.9% of the entire native flora), subdivided in 231 species, 103 subspecies and 15 hybrids and belonging to 149 genera and 43 families. Among the 231 species, 69 are considered endemic to Croatia and confined to a small area (< 4,500 km2), while 162 are considered range restricted species, which have larger ranges and/or are shared with neighbouring countries. The genera Centaurea and Hieracium have the highest number of endemic and range restricted taxa. Spatial analyses indicated two notable centres of species richness—the mountainous Dinaric Alps and the SE Adriatic coast, including the islands. Regions with a high richness of range-restricted taxa did not coincide with areas of high richness of endemic species. Taxa exhibited modest bimodality with respect to altitudinal distribution. In addition, the greatest diversity of taxa is concentrated in northwest of Croatia and could be related to differences in mean annual air temperatures and the duration of insolation. As regards their conservation status, 13 of the 349 taxa are endangered, and 62 are near threatened or vulnerable. Despite relatively strong legal protection of endemic and range restricted species, 37 taxa remain unprotected. Changes in conservation practice are therefore proposed.

Climate Change and Sustaining Heritage Resources: A Framework for Boosting Cultural and Natural Heritage Conservation in Central Italy

Climate change has dramatically affected the rainfall patterns and water systems in Central Italy. The vulnerability of this area to climate change and natural hazards necessitates that appropriate adaptation policies be put in place to protect heritage sites. This study aims to develop a cultural and natural heritage conservation framework for Central Italy that enhances the capacity of climate change adaptation for heritage resources. For this purpose, a comparison was made between the UNESCO (United National Educational, Scientific and Cultural Organization) Convention of 1972 and the European Landscape Convention of the Council of Europe to achieve a coherent vision for the protection of heritage resources in Europe. After describing the impacts of climate change on heritage resources in Central Italy, we analyze and suggest improvements to the conservation framework for wisely protecting heritage resources in a changing climate. The findings reveal that conservation sectors require assessments of the value of heritage resources at the territorial scale to effectively define conservation priorities, assess the vulnerabilities, and more precisely direct funding. In this respect, the integration of the European Landscape Convention with territorial planning may boost the unity of a conservation framework in terms of climate change while providing new opportunities for conservation authorities to develop adaptation policies.

Drilling Down Hotspots of Intraspecific Diversity to Bring Them Into On-Ground Conservation of Threatened Species

Unprecedented rates of biodiversity loss raise the urgency for preserving species ability to cope with ongoing global changes. An approach in this direction is to target intra-specific hotspots of genetic diversity as conservation priorities. However, these hotspots are often identified by sampling at a spatial resolution too coarse to be useful in practical management of threatened species, hindering the long-appealed dialog between conservation stakeholders and conservation genetic researchers. Here, we investigated the spatial and temporal variation in species presence, genetic diversity, as well as potential risk factors, within a previously identified hotspot of genetic diversity for the endangered Apennine yellow bellied toad Bombina pachypus. Our results show that this hotspot is neither a geographically homogeneous nor a temporally stable unit. Over a time-window spanning 10-40 years since previous assessments, B. pachypus populations declined in large portions of its hotspot, and their genetic diversity levels decreased. Considering the demographic trend, genetic and epidemiological data, and models of current and future climatic suitability, populations at the extreme south of the hotspot area still qualify for urgent in-situ conservation actions, whereas northern populations would be better managed through a mix of in-situ and ex-situ actions. Our results emphasize that identifying hotspot of genetic diversity, albeit an essential step, does not suffice to warrant on-ground conservation of threatened species. Hotspots should be analysed at finer geographic and temporal scales, to provide conservation stakeholders with key knowledge to best define conservation priorities, and to optimize resource allocation to alternative management practices.

Insights into the genetic diversity of indigenous goats and their conservation priorities

ObjectiveAn experiment was conducted to evaluate genetic diversity of 26 Chinese indigenous goats by 30 microsatellite markers, and then to define conservation priorities to set up the protection programs according to the weight given to within- and between-breed genetic diversity.MethodsTwenty-six representative populations of Chinese indigenous goats, 1,351 total, were sampled from different geographic regions of China. Within-breed genetic diversity and marker polymorphism were estimated calculating the mean number of alleles, observed heterozygosities, expected heterozygosities, fixation index, effective number of alleles and allelic richness. Conservation priorities were analyzed by statistical methods.ResultsA relatively high level of genetic diversity was found in twenty-four population; the exceptions were in the Daiyun and Fuqing goat populations. Within-breed kinship coefficient matrices identified seven highly inbred breeds which should be of concern. Of these, six breeds receive a negative contribution to heterozygosity when the method was based on proportional contribution to heterozygosity. Based on Weitzman or Piyasatian and Kinghorn methods, the breeds distant from others i.e. Inner Mongolia Cashmere goat, Chengdu Brown goat and Leizhou goat obtain a high ranking. Evidence from Caballero and Toro and Fabuel et al method prioritized Jining Gray goat, Liaoning Cashmere goat, and Inner Mongolia Cashmere goat, which agree with results from Kinship-based methods.ConclusionConservation priorities were determined according to multiple methods. Our results suggest Inner Mongolia Cashmere goat (most methods), Jining Gray goat and Liaoning Cashmere goat (high contribution to heterozygosity and total diversity) should be prioritized based on most methods. Furthermore, Daiyun goat and Shannan White goat also should be prioritized based on consideration of effective population size. However, if one breed can continually survive under changing conditions, the straightforward approach would be to increase its utilization and attraction for production via mining breed germplasm characteristics.

Overcoming the worst of both worlds: integrating climate change and habitat loss into spatial conservation planning of genetic diversity in the Brazilian Cerrado

Conservation strategies aiming to safeguard species genetic diversity in the Cerrado are urgent. The biome is an agriculture frontier and lost at least 50% of its natural capital since the early 1950s, with the highest rate of vegetation clearing among all Brazilian biomes. Here we match information on geographic range shifts in response to climate changes and habitat loss to define conservation priorities for species genetic diversity using Eugenia dysenterica, a widely distributed tree across the Brazilian Cerrado. We found a set of 27 optimal solutions in which a minimum of 12 out of 23 populations are necessary to represent all 208 alleles of the species. Environmental suitability predicted for 2050 was higher for populations in the southern region of the Cerrado, whereas the proportion of natural remnants around populations expected for 2030 was lower in this same region. Thus, it seems to be more conservative to adopt “in situ” strategies in the northwestern part of the species range to hold more genetic diversity in areas harboring high numbers of natural remnants, despite the likely reduction in climatic suitability. On the other hand, in the southern and southeastern region of the range, despite more stability from a climatic point of view, there was a serious constraint given the high levels of human occupation; in this case, “ex situ” strategies might be a better option for the species. Our results and proposed priorities enable different strategies for making an operational approach for conservation of genetic diversity. Adopting different prioritization strategies for stable and unstable regions (both in climatic suitability and natural remnants) in the future would allow, in principle, to avoid “the worst of both worlds” to achieve an efficient conservation program for the species.

Over-winter ecology and relative density of Canada Warbler Cardellina canadensis in Colombia: the basis for defining conservation priorities for a sharply declining long-distance migrant

SummaryThe Canada Warbler Cardellina canadensis is a steeply declining Neotropical migratory bird and > 50% of its non-breeding range is within the Colombian Andes. Despite being an abundant migrant in Andean forests, the species’ elevational distribution and non-breeding ecology have yet to be studied, thereby precluding the design of effective conservation actions. During four non-breeding periods (2012–2016), we surveyed Colombia’s three Andean ranges, carrying out passive 5-minute point counts between 700 and 3,150 m asl in five habitats (mature forest, secondary growth, forest edges/riparian forest, shade coffee, sun coffee), recording the perpendicular distance, sex, foraging height, and association with mixed species flocks of Canada Warbler. Habitat variables were recorded at each point. Based on 819 passive point counts, Canada Warblers occupied elevations between 750 and 2,300 m, being more abundant between 1,000 and 2,200 m. Relative densities were higher in mature forest compared to shade coffee and secondary forest, and accordingly abundance increased with canopy height. There was no evidence for a difference in elevation or habitat use by males and females. Within forests, birds foraged at mid-levels, 5–15 m above the ground, and the probability of Canada Warblers occurring in mixed species flocks increased with elevation. Models of variation in relative density throughout the Eastern Andes showed a positive relation with cloud cover and above-ground forest biomass, implying a preference for humid, forested regions. Of the areas in the Eastern Andes with high predicted relative density, ∼ 14% overlapped with protected areas and we identify priority areas where protective measures could benefit the conservation status of the species. For maximum effectiveness, conservation actions should focus on protecting forest fragments and initiating reforestation projects at mid-elevations (1,000–2,200 m), as well as supporting agroforestry practices in humid regions of the Colombian Andes.

Aplicación de índices filogenéticos para la definición de prioridades de conservación en los páramos del noroeste de los Andes

Paramos are High Andean ecosystems that harbor a diverse biota and have high endemicity, as a result of their extreme environmental conditions. We used different phylogenetic indices to define conservation priorities in the paramos of the department of Antioquia, Colombia, based on measures of their evolutionary individuality and richness complimentary. To perform the analyses, we generated a data base including 416 angiosperm taxa and 1 951 localities for a total of 12 897 distributional records compiled from surveys and reviews. Additionally, the available information in the Global Biodiversity Information Facility and the Colombian Biodiversity Information System were included. From these data, priority areas for the conservation of the paramos located in the state of Antioquia were identified, using measures of evolutionary individuality based on nodes and biotic complementarity. Taking into account only the individual phylogenetic indices, the most important paramo for conservation was Frontino-Urrao, followed by Farallones de Citará. If biotic complementarity is considered, the second most important paramo is Sonsón. Priority classifications of areas based on individuality are congruent with areas of greatest species richness. We conclude that it is necessary and urgent to preserve the paramos given their vulnerability and the subsequent loss of the ecosystem services that they provide, if they are exposed to degradation or disappearance.

Conservation priorities to protect vertebrate endemics from global urban expansion

Earth is undergoing unprecedented urban growth, with urban areas forecasted to increase by 120 million ha from 2000 to 2030, impacting natural habitat. However, to date it is unclear where conservation investments can best mitigate biodiversity loss due to urban expansion into natural habitat. Here we combine spatially-explicit global forecasts of urban expansion, information on terrestrial vertebrate endemism, and data on current land cover and protected areas to define conservation priorities. Globally, 13% of endemics are in ecoregions under high threat from urban expansion. Biodiversity losses are highly spatially concentrated, with 78% of endemics threatened by urban growth occurring in just 30 priority ecoregions (4% of all ecoregions). Natural habitat protection of 4.1–8.0 million ha, <7% of total forecasted urban expansion, would be needed in these priority ecoregions. As an added benefit, such protection would also reduce GHG emissions by an amount worth up to 87.6 billion USD.

Ranked Tree Shapes, Nonrandom Extinctions, and the Loss of Phylogenetic Diversity.

Phylogenetic diversity (PD) is a measure of the evolutionary legacy of a group of species, which can be used to define conservation priorities. It has been shown that an important loss of species diversity can sometimes lead to a much less important loss of PD, depending on the topology of the species tree and on the distribution of its branch lengths. However, the rate of decrease of PD strongly depends on the relative depths of the nodes in the tree and on the order in which species become extinct. We introduce a new, sampling-consistent, three-parameter model generating random trees with covarying topology, clades relative depths, and clades relative extinction risks. This model can be seen as an extension to Aldous' one parameter splitting model ($\beta$, which controls for tree balance) with two additional parameters: a new parameter $\alpha$ quantifying the relation between age and richness of subclades, and a parameter $\eta$ quantifying the relation between relative abundance and richness of subclades, taken herein as a proxy for overall extinction risk. We show on simulated phylogenies that loss of PD depends on the combined effect of all three parameters, $\beta$, $\alpha,$ and $\eta$. In particular, PD may decrease as fast as species diversity when high extinction risks are clustered within small, old clades, corresponding to a parameter range that we term the "danger zone" ($\beta<-1$ or $\alpha<0$; $\eta>1$). Besides, when high extinction risks are clustered within large clades, the loss of PD can be higher in trees that are more balanced ($\beta>0$), in contrast to the predictions of earlier studies based on simpler models. We propose a Monte-Carlo algorithm, tested on simulated data, to infer all three parameters. Applying it to a real data set comprising 120 bird clades (class Aves) with known range sizes, we show that parameter estimates precisely fall close to the danger zone: the combination of their ranking tree shape and nonrandom extinctions risks makes them prone to a sudden collapse of PD.

Diversity, distribution and conservation of the terrestrial reptiles of Oman (Sauropsida, Squamata).

In the present work, we use an exceptional database including 5,359 records of 101 species of Oman’s terrestrial reptiles together with spatial tools to infer the spatial patterns of species richness and endemicity, to infer the habitat preference of each species and to better define conservation priorities, with especial focus on the effectiveness of the protected areas in preserving this unique arid fauna. Our results indicate that the sampling effort is not only remarkable from a taxonomic point of view, with multiple observations for most species, but also for the spatial coverage achieved. The observations are distributed almost continuously across the two-dimensional climatic space of Oman defined by the mean annual temperature and the total annual precipitation and across the Principal Component Analysis (PCA) of the multivariate climatic space and are well represented within 17 out of the 20 climatic clusters grouping 10% of the explained climatic variance defined by PC1 and PC2. Species richness is highest in the Hajar and Dhofar Mountains, two of the most biodiverse areas of the Arabian Peninsula, and endemic species richness is greatest in the Jebel Akhdar, the highest part of the Hajar Mountains. Oman’s 22 protected areas cover only 3.91% of the country, including within their limits 63.37% of terrestrial reptiles and 50% of all endemics. Our analyses show that large areas of the climatic space of Oman lie outside protected areas and that seven of the 20 climatic clusters are not protected at all. The results of the gap analysis indicate that most of the species are below the conservation target of 17% or even the less restrictive 12% of their total area within a protected area in order to be considered adequately protected. Therefore, an evaluation of the coverage of the current network of protected areas and the identification of priority protected areas for reptiles using reserve design algorithms are urgently needed. Our study also shows that more than half of the species are still pending of a definitive evaluation by the International Union for Conservation of Nature (IUCN).

Conservation Below the Species Level: Suitable Evolutionarily Significant Units among Mountain Vipers (the Montivipera raddei complex) in Iran.

Northern and western mountains of Iran are among the most important biodiversity and endemism hot spots for reptiles in the Middle East. Among herpetofauna, the montivipers represent an emblematic and fragmented endemic group for which estimating their level of genetic differentiation and defining conservation priorities is urgently needed. Here, we present the most comprehensive phylogenetic study on the Montivipera raddei species group comprising all 5 known taxa, among which 3 are endemic to Iran. Based on 2 mitochondrial genes, phylogenetic and phylogeographic analyses revealed 3 major lineages each presenting very contrasting distribution areas. The Iranian montivipers are highly structured in clades showing low genetic diversity and corresponding to high altitude summits. Molecular dating revealed the role of Quaternary paleo-climatic oscillations and altitudinal movements of montivipers in shaping genetic diversity and differentiation of these sky-island taxa. In addition, the best scenario of historical biogeography allowed identifying 3 possible refugial areas in Iran most likely arising by vicariance. Based on our mitochondrial results and pending additional data, we recognize 3 candidate species among the M. raddei complex: M. raddei, Montivipera latifii, and Montivipera kuhrangica that are coherent with their geographical distribution. We propose that the most appropriate evolutionary significant units for conservation of the montivipers are represented by 13 units among which 6 are recognized as high priority. Finally, we suggest some recommendations to the IUCN as well as to the Iranian conservation policies with respect to conservation prioritization.

Do large-seeded herbs have a small range size? The seed mass-distribution range trade-off hypothesis.

We aimed to introduce and test the “seed mass–distribution range trade‐off” hypothesis, that is, that range size is negatively related to seed mass due to the generally better dispersal ability of smaller seeds. Studying the effects of environmental factors on the seed mass and range size of species, we also aimed to identify habitats where species may be at risk and need extra conservation effort to avoid local extinctions. We collected data for seed mass, global range size, and indicators for environmental factors of the habitat for 1,600 species of the Pannonian Ecoregion (Central Europe) from the literature. We tested the relationship between species’ seed mass, range size, and indicator values for soil moisture, light intensity, and nutrient supply. We found that seed mass is negatively correlated with range size; thus, a seed mass–distribution range trade‐off was validated based on the studied large species pool. We found increasing seed mass with decreasing light intensity and increasing nutrient availability, but decreasing seed mass with increasing soil moisture. Range size increased with increasing soil moisture and nutrient supply, but decreased with increasing light intensity. Our results supported the hypothesis that there is a trade‐off between seed mass and distribution range. We found that species of habitats characterized by low soil moisture and nutrient values but high light intensity values have small range size. This emphasizes that species of dry, infertile habitats, such as dry grasslands, could be more vulnerable to habitat fragmentation or degradation than species of wet and fertile habitats. The remarkably high number of species and the use of global distribution range in our study support our understanding of global biogeographic processes and patterns that are essential in defining conservation priorities.

A multi-stakeholder strategy to identify conservation priorities in Peninsular Malaysia

Malaysia, with its rapidly growing economy, exemplifies the tensions between conservation and development faced by many tropical nations. Here we present the results of a multi-stakeholder engagement exercise conducted to (1) define conservation priorities in Peninsular Malaysia and (2) explore differences in perceptions among and within stakeholder groups (i.e. government, academia, NGOs and the private sector). Our data collection involved two workshops and two online surveys where participants identified seven general conservation themes and ranked the top five priority issues within each theme. The themes were: (1) policy and management, (2) legislation and enforcement, (3) finance and resource allocation, (4) knowledge, research and development, (5) socio-economic issues, (6) public awareness and participation and (7) rights of nature. In spite of their very different backgrounds and agendas, the four stakeholder groups showed general agreement in their priority preferences except for two issues. Respondents from government and private sector differed the most from each other in their priority choices while academia and NGO showed the highest degree of similarity. This ranked list of 35 conservation priorities is expected to influence the work of policy-makers and others in Peninsular Malaysia and can be used as a model to identify conservation priorities elsewhere.

On the importance of taking into account agricultural practices when defining conservation priorities for regional planning

Conserving biodiversity in managed landscapes requires the definition of spatial conservation priorities. The systematic conservation planning tools which are used to define these conservation priorities, assess the vulnerability of different locations by combining two different elements: some measurement of the biological assets in question, and some measurement of the key processes which threaten these biological assets. For instance, in cumulative impact mapping, maps of individual human activities that impact ecosystems (hereafter referred to as ‘stressor’ for individual maps and ‘cumulative stressor’ for combined maps) are overlaid with maps of ecosystem vulnerability, in order to estimate the overall ecological impact of human activities on natural ecosystems. These tools are appealing because they are easy to use and inform regional land planning. However, given that once these spatial conservation priorities are defined they potentially have far-reaching consequences, there is a need to test their robustness and reliability. Here we propose to investigate how the uncertainties related to the estimation of a cumulative stressor layer affect the definition of spatial conservation priorities. We conduct a sensitivity analysis of the different ways of estimating major stressors related to human activities (transport, urbanization and population) with a specific focus on agriculture. We show that spatial conservation priorities are little sensitive to most of the parameters and input data used to estimate the cumulative stressor map. In particular, they are not very sensitive to changes in spatially overlapping stressors, i.e. those which overlap spatially with other stressors. However, our analyses also reveal that spatial conservation priorities are highly sensitive to how the agriculture stressor is defined. These results highlight the importance of better understanding how agricultural activities impact biodiversity and establishing how more accurate information on agricultural practices can be used to define spatial conservation priorities.