Research articleConservation gaps and priorities in the Tropical Andes biodiversity hotspot: Implications for the expansion of protected areas
Introduction
Anthropogenically driven changes to natural ecosystems constitute the leading cause of global biodiversity loss (Pimm and Raven, 2000, Newbold et al., 2015), posing eminent threats to ecosystem services provisioning (Foley et al., 2005, Harrison et al., 2014) and human well-being (Haines-Young and Potschin, 2010, Bennett et al., 2015). According to conservative estimates, current rates of species extinction are believed to be a factor 100 times higher than natural extinction rates in the absence of humans (Ceballos et al., 2015). Major concerns exist regarding the rapid loss and degradation of tropical ecosystems, where most of the world's terrestrial biodiversity is found (Myers et al., 2000, Brook et al., 2003). Between 1990 and 2010, gross loss of tropical forest cover was about 1.6 million km2 (Achard et al., 2014), an area that almost equals the size of Alaska. While projections of land-use change across tropical regions vary widely in magnitude and accuracy, land-use change trajectories will certainly shape the survival and extinction rates of species in the future (Wright and Muller-Landau, 2006, Gibson et al., 2011).
In the effort to minimize the loss of species and their habitats, the extent of protected areas (PAs) has expanded rapidly over the last 20 years, covering now almost 15% of earth's terrestrial and inland water surface area (IUCN and UNEP-WCMC, 2016). Effective PAs must adequately represent biodiversity and secure its persistence in the future (Margules et al., 2002). However, it is important to identify and prioritize areas where the protection of biodiversity is most urgently needed, as resources to establish and manage PAs are limited (Waldron et al., 2013), especially in tropical regions (Lessmann et al., 2016).
Historically, PAs have been largely established without strategic or organized planning, which has resulted in severe shortcomings of current networks (Venter et al., 2014, Jenkins et al., 2015). Specifically, the concepts of “irreplaceability” and “vulnerability”, which are key principles in conservation planning theory (Margules and Pressey, 2000), are not well incorporated in the process of PA development (Rodrigues et al., 2004). The irreplaceability value of a potential conservation area reflects to what extent conservation targets (such as the number of species or populations) are compromised if the area were to be lost (Ferrier et al., 2000). In other words, highly irreplaceable areas have few or no alternatives to achieve a region's conservation targets, implying that maintaining their ecological features should be prioritized. Species endemism is often used as a measure of irreplaceability (Brooks et al., 2006), as endemic species are found in areas for which no spatial replacements exist elsewhere. On the other hand, vulnerability reflects the likelihood that a species will be lost in the future as a result of anthropogenic processes (Pressey and Taffs, 2001). Vulnerable areas are often identified based on spatial and environmental variables that indicate potential habitat loss (Brooks et al., 2006), such as population density and land-use change. Both irreplaceability and vulnerability must be considered simultaneously for the effective prioritization of PAs (Margules and Pressey, 2000). Certainly, areas with high irreplaceability contain important ecological features; however, the urgency of protecting these is low in the absence of land-use threats. Likewise, an area vulnerable to land-use change that is classified as low irreplaceability is not necessarily a conservation priority, since there are other options to conserve the same ecological features (Rodrigues et al., 2004).
Biodiversity is often concentrated in areas that are subjected to high rates of anthropogenic disturbance (Baillie et al., 2004). Accordingly, in the influential work by Myers et al. (2000), twenty-five areas known as the world's biodiversity hotspots were identified, where extraordinary richness of endemic plant and vertebrate species is confronted by dramatic habitat loss. In terms of endemic species, the Tropical Andes (TA) region has been identified as the leading hotspot, which makes it a key priority region for conservation planning and research efforts (Mittermeier et al., 2011). Nevertheless, the degree to which endemic species in the TA are covered by existing PAs is unknown, and it is currently not clearly understood where the expansion of PAs is most urgently required to further halt their irreversible losses. Several prior studies have identified conservation gaps across the TA. For instance, Lessmann et al. (2014) found that only 42% of the species in the Ecuadorian Andes achieve conservation goals, while existing PAs in the region need to be doubled to provide sufficient coverage for all species. Other studies have evaluated the protection of particular endangered species such as the Mountain Tapir (Tapirus pinchaque) (Lizcano et al., 2015, Ortega-Andrade et al., 2015). Yet, the focus of these studies was generally to evaluate PA networks at the country level. However, given that the geographical range of a species is not restricted by national borders, evidently other spatial prioritizations for conservation could be available if we consider the additional range of species' distribution across neighboring countries. This, consequently, changes how we classify sites in terms of irreplaceability, vulnerability and species representativeness scenarios (Pressey et al., 1994). Thus, only a region-wide assessment could generate a comprehensive understanding of the conservation gaps and priorities throughout the TA.
Here, we assess to what extent PAs in the TA provide coverage for 1743 endemic or nearly endemic vertebrate species (including mammals, birds, amphibians and reptiles), and identify priority areas for conservation. We use updated geographical range maps for each species, considering the information available about elevation and habitat requirements, and address the following research objectives: 1) to determine the number of endemic vertebrate species not adequately represented by existing PAs within the TA, and 2) to localize the areas where the expansion of PAs should be prioritized.
Section snippets
Study area
The Andean mountain range can be divided into three subregions, based on the variation in climate and topography (Perucca and Angillieri, 2009): (1) the Dry Andes located in northern Chile and Argentina, (2) the Wet Andes located in Southern Chile and Argentina, and (3) the Tropical Andes, running from the far north of Chile and Argentina, through Bolivia, Peru, Ecuador, Colombia and Venezuela. The TA extend over 1.5 million km2, between the latitudinal range of 11° N to 30° S, and the
Results
Out of the 1762 species considered, the geographical range of 19 species did not correspond to the elevational and habitat requirements as reported by the IUCN and BirdLife International, reducing the final database to a total of 1743 species. On average, the refinement by elevation and land-cover decreased the range size by 64% (SD ± 22). For 47 species, the range was reduced to less than 10 km2, while for an additional 217 species, the range was reduced to less than 100 km2. Range reductions
Discussion
This study provided a region-wide conservation assessment of endemic vertebrate species in the TA. It shows how current PA networks fail to capture the region's species diversity, with striking differences in the level of protection between taxa and countries. PAs in the Chilean, Peruvian and Colombian Andes show the worst performance, both in terms of the total proportion of species protected and the relative extent of land area covered. Peru and Colombia harbor a greater portion of
Conflicts of interest
None.
Acknowledgement
We thank five anonymous reviewers for their helpful comments on an earlier version of the manuscript. Financial support was provided by Universidad de Ciencias y Humanidades.
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