Patterns of species richness hotspots and estimates of their protection are sensitive to spatial resolution

Increasing taxonomic diversity and spatial resolution clarifies opportunities for protecting US imperiled species

Continental- and regional-scale assessments of gaps in protected area networks typically use relatively coarse range maps for well documented species groups, creating uncertainty about the fate of unexamined biodiversity and providing insufficient guidance for land managers. By building habitat suitability models for a taxonomically diverse group of 2216 imperiled plants and animals, we revealed comprehensive and detailed protection opportunities in the conterminous United States. Summing protection-weighted range-size rarity (PWRSR, the product of the percent of modeled habitat outside of protected areas and the inverse of modeled habitat extent) uncovered novel patterns of biodiversity importance. Concentrations of unprotected imperiled species in places such as the northern Sierra Nevada, central and northern Arizona, the Rocky Mountains of Utah and Colorado, southeastern Texas, southwestern Arkansas, and Florida's Lake Wales Ridge have rarely if ever been featured in continental- and regional-scale analyses. Inclusion of diverse taxa (vertebrates, freshwater mussels, crayfishes, bumble bees, butterflies, skippers, and vascular plants) partially drove these new patterns. When analyses were restricted to groups typically included in previous studies (birds, mammals, and amphibians), up to 53% of imperiled species in other groups were left out. The finer resolution of modeled inputs (990 m) also resulted in a more geographically dispersed pattern. For example, 90% of the human population of the conterminous United States lives within 50 km of modeled habitat for one or more species with high PWRSR scores. Over one-half of the habitat for 818 species occurs within federally lands managed for biodiversity protection; an additional 360 species have over one-half of their modeled habitat on federal multiple use land. Freshwater animals occur in places with poorer landscape condition but with less exposure to climate change than other groups, suggesting that habitat restoration is an important conservation strategy for these species. The results provide fine-scale, taxonomically diverse inputs for local and regional priority-setting and show that although protection efforts are still widely needed on private lands, notable gains can be achieved by increasing protection status on selected federal lands.

The Value of Trail Corridors for Bold Conservation Planning

Conservationists are calling for bold strategies to connect wildlands and halt extinctions. A growing number of scientists recommend that 50% of all land must be held in a protected area network to maintain biodiversity. We assessed lands adjacent to the Pacific Crest Trail (PCT) and Continental Divide Trail (CDT) as possible wildlife corridors connecting protected areas in the American West. We evaluated the connectivity, wildness, and biodiversity values of the lands of each corridor and determined the conservation and land management status. We found that our corridors connect 95 protected areas creating two linear protected area chains from Mexico to Canada. Both the PCT and CDT corridors follow many of the best corridor routes previously found in the literature and hold high wildland conservation values. The American public already owns the majority of land units around the modeled PCT (88%) and CDT (90%) corridor. Therefore, we recommend further analysis of the lands adjacent to recreational trails as wildlife corridors. Employing our methodology on multiple scales could reveal that other recreational trails should be buffered and conserved for wildlife movement.

Setting the priorities straight - Species distribution models assist to prioritize conservation targets for the mangroves

Mangrove forests provide a wide range of ecosystem services, yet they are declining rapidly due to climate change and human activities. Identification of conservation priority targets across spatial and temporal scales may assist in planning and decision making, especially in areas having rich mangrove diversity but with limited response capacity. In this study, we aimed to identify the species and areas which should be prioritized for conservation in the Indo-West Pacific (IWP) region, one of the two global hotspots of mangroves. We used an ensemble species distribution modelling framework to map the potential distribution of ten species, including true mangroves and mangrove associates, in current, past, and future environmental conditions. The priority targets were then identified through a weighted-scoring approach with the current distribution and the modelled outputs. Our study revealed that precipitation and surface elevation could influence the distribution of the true mangroves, while the temperature was the important variable for the mangrove associates. Although suitable habitat for the mangroves is predicted to increase in future, primarily due to the northward range expansion of six species, areas with high species richness would decrease. We found 7.09% and 4.16% areas of the IWP should be prioritized for conservation of the true mangroves and mangrove associates, respectively. The characteristics of these priority sites indicated that the inclusion of the anthropogenic component in the conservation framework and species-targeted management plans in the protected areas are required for the effective implementation of conservation actions. Five of the studied species, namely Acanthus ilicifolius, Dolichandrone spathacea, Heritiera littoralis, Pemphis acidula and Xylocarpus granatum, were found to have the highest priority score for conservation. The glacial refugia of the species, mostly distributed in the Philippines, New Guinea, southern India and Madagascar, should be explored further for species-specific conservation actions.

Applying Biodiversity Metrics as Surrogates to a Habitat Conservation Plan

Unabated urbanization has led to environmental degradation and subsequent biodiversity loss across the globe. As an outcome of unmitigated land use, multi-jurisdictional agencies have developed land use plans that attempt to protect threatened or endangered species across selected areas by which some trade-offs between harm to species and additional conservation approaches are allowed among the partnering organizations. Typical conservation plans can be created to focus on single or multiple species, and although they may protect a species or groups of species, they may not account for biodiversity or its protection across the given area. We applied an approach that clustered deductive habitat models for terrestrial vertebrates into metrics that serve as surrogates for biodiversity and relate to ecosystem services. In order to evaluate this process, we collaborated with the partnering agencies who are creating a Multi-Species Habitat Conservation Plan in southern California and compared it to the entire Mojave Desert Ecoregion. We focused on total terrestrial vertebrate species richness and taxon groupings representing amphibians, birds, mammals, and reptiles, and two special status species using the Normalized Index of Biodiversity (NIB). The conservation planning area had a lower NIB and was less species rich than the Mojave Desert Ecoregion, but the Mojave River riparian corridor had a higher NIB and was more species-rich, and while taxon analysis varied across the geographies, this pattern generally held. Additionally, we analyzed desert tortoise (Gopherus agassizii) and desert kit fox (Vulpes macrotis arsipus) as umbrella species and determined that both species are associated with increased NIB and large numbers of species for the conservation area. Our process provided the ability to incorporate value-added surrogate information into a formal land use planning process and used a metric, NIB, which allowed comparison of the various planning areas and geographic units. Although this process has been applied to Apple Valley, CA, and other geographies within the U.S., the approach has practical application for other global biodiversity initiatives.

Benthic diversity patterns and predictors: A study case with inferences for conservation

Understanding which drivers cause diversity patterns is a key issue in conservation. Here we applied a spatially explicit model to predict marine benthic diversity patterns according to environmental factors in the NW Mediterranean Sea. While most conservation-oriented diversity studies consider species richness only and neglect equitability, we measured separately species richness, equitability, and 'overall' diversity (i.e., the Shannon-Wiener H' function) on a dataset of 890 benthic species × 209 samples. Diversity values were predicted by means of Random Forest regression, on the basis of 10 factors: depth, distance from the coast, distance from the shelf break, latitude, sea-floor slope, sediment grain size, sediment sorting, distance from harbours and marinas, distance from rivers, and sampling gear. Predictions by Random Forests were accurate, the main predictors being latitude, sediment grain size, depth and distance from the coast. Based on predicted values, diversity hotspots were identified as those localities where indices were in the 15% top segment of ranked values. Only a minority of the diversity hotspots was included within the boundaries of the protection institutes established in the region. Marine protected areas are often created in sites harbouring important coastal habitats, which risks neglecting the diversity hidden in the sedimentary seafloor. We suggest that marine protected areas should accommodate portions of sedimentary habitat within their boundaries to improve diversity conservation.