Climate change affects the distribution of cacti species of the genus Melocactus in the Brazilian Caatinga

Abstract Predicted climate change will cause higher temperatures, less rainfall, and aridification of the most extensive tropical dry forest region in South America (Caatinga) as this century progresses. Climate change has significantly impacted the distribution of plant species, especially in arid lands. This study combined broad-scale mechanisms to investigate if climate change affects the expansion and contraction of the geographical range of cacti species in the Caatinga, Brazil. The specific objectives of this study were to (1) assess the contribution of environmental variables in explaining the distribution of cactus species of the genus Melocactus ; (2) Identify the effect of climate change on three endemic cacti species’ range-shift forecasts; and (3) evaluate the impacts of climate change on the definition of potential suitable areas of expansion and contraction. The range changes of these species were evaluated under two Shared Socioeconomic Pathways (SSP), SSP2 and SSP5, for two time periods centered on 2050 and 2070. Results showed that the maximum temperature of warmest month variable had the most significant importance for Melocactus bahiensis and Melocactus ernestii and the annual precipitation variable for Melocactus zehntneri . Results also showed that significant changes will occur in the baseline suitable area in the SSP5 scenario in 2070, driven by the contraction. Additionally, results indicated that Melocactus ernestii might lose 97%, whereas M. bahiensis and M. zehntneri may lose 91% and 50% of their baseline ranges, respectively. They also show that species mainly influenced by temperature are expected to be the biggest losers of climate change. Our findings can help conserve areas projected to stay or become suitable and protect species in their current and future ranges.