Assessing the impact of climate change on threatened endemic vascular plants of Argentina

Abstract

Biodiversity loss due to climate change is one of the most critical current environmental problems. Global warming is causing substantial species-range shifts and local extirpations, especially for species with restricted distribution ranges. Studies of impact of the climate change on species ranges and environmental suitability have become a fundamental tool for evaluating conservation strategies. However, one important limitation of these approaches is that only species with an adequate number of spatially distinct occurrence records can be modelled, generally excluding threatened rare species from the analyses, a situation referred to as the ‘rare species modelling paradox’. To overcome this limitation, we analysed the effect of climate change on the richness of threatened endemic plants of Argentina employing a macroecological modelling approach, using three different modelling techniques (generalized linear mixed models – GLMM, generalized additive models – GAM, and boosted regression trees – BRT), four general circulation models, two representative CO2 concentration pathways (RCPs), and two time periods (2050 and 2070). We identified grid cells with the greatest decline in numbers of threatened endemics, determined species composition in these cells and characterized their vulnerability using three indices. A loss of species richness is observed in ca 83% of the cells, and both protected areas and hotspots of threatened species show significant decrease in future species richness. We identified 32 most affected cells under future climatic projections, including a total of 370 threatened endemic species and exhibiting high beta diversity values (high dissimilarity) among most of the cells. Cells with the highest vulnerability were located along the Central Andes of northwestern Argentina, along the Southern Andean Yungas, High Monte and Central Andean Puna ecoregions, and including a total of 118 threatened endemics (15% of those registered for Argentina) with greater representation of Asteraceae, Apocynaceae, Cactaceae and Iridaceae. However, coverage of protected area network is less than 5% for each of these cells. Our results highlight the urgent need for both in situ and ex situ conservation policies and strategies for the vascular flora of Argentina.