Climate change and the potential expansion of buffelgrass (Cenchrus ciliaris L., Poaceae) in biotic communities of Southwest United States and northern Mexico

In the last decades, more than six hundred exotic species have become established throughout the region of the southwestern United States and northwestern Mexico, including the African buffelgrass (Cenchrus ciliaris L.). Buffelgrass often causes negative impacts on natural ecosystems and it is considered a highly invasive species in many parts of the world. We used 18,550 records from 260 datasets and species distribution modeling (SDM) to provide support for the climatically based and topographic hypotheses, which claim that current climate and topography affect species distribution patterns of plants. We also investigated (1) the geographical distribution of habitat suitability across biotic communities of the Southwest United States and northern Mexico, (2) the association between habitat suitability, climate variables and topography, and (3) the potential effects of climate change on the future distribution of buffelgrass. We found that the geographic pattern of suitability in the southwest generally increases west- and southward, with some high suitability areas also occurring in southern areas of Arizona, USA, and across the state of Sonora, Mexico. We observed that mean temperature and annual precipitation explain spatial variation in suitability better than other climatic and non-climatic variables. Climate change models indicated significant opportunities for contraction across the buffelgrass’ range and fewer for range expansion. In all scenarios, SDMs predicted a high contraction of suitable habitat. Most of these contractions would occur in portions of the Sonoran Desert and the foothills of the Sierra Madre Occidental. We show, for the first time, the potential changes in buffelgrass habitat suitability across major biomes of the Southwest region, under future climate change scenarios.