Predicting Climate Change Impacts on Candelilla (Euphorbia antisyphilitica Zucc.) for Mexico: An Approach for Mexico’s Primary Harvest Area

Candelilla (Euphorbia antisyphilitica Zucc.) is a non-timber forest resource of ecological and economic importance in the arid zones of Mexico due to the commercialization of its wax for industrial purposes. The objectives of this study were (i) to delimit areas of current and projected future candelilla habitat suitability in Mexico and in the state of Coahuila, (ii) to determine the most important variables that define candelilla habitat, and (iii) to propose areas for candelilla conservation under climate change conditions in Coahuila. Records of candelilla presence, current and future bioclimatic layers from the MPIESM-LR and HadGEM2-ES models with two scenarios RCP 4.5 and 8.5, were used to create species distribution models with soil and topographical variables. MaxEnt software was used to project current habitat suitability zones under climate change. We estimated the current surface area of candelilla in Mexico to be 79,336.87 km2, and for Coahuila 25,620.75 km2. In Coahuila, using the MPIESM-LR model for 2050, the estimate was 20,177.67 km2 and 17,079.61 km2 for RCP scenarios 4.5 and 8.5; while for 2070, the estimate was 12,487.18 km2 and 9812.94 km2 for RCP scenarios 4.5 and 8.5. For the HadGEM2-ES model for 2050, the estimate was 20,066.40 km2 and 17,079.61 km2; for 2070 it was 17,156.02 km2 and 16,073.70 km2. As proposed areas for conservation of candelilla in the face of climate change, we estimated 5435.06 km2 and 3636.96 km2. The study area was located in the northwest and center of the state of Coahuila, near the natural protected areas of Ocampo and Bajo Rio San Juan, areas that are resilient to climate change. The results obtained provide information on the environmental and site conditions for the establishment of candelilla in Mexico, as well as the geographical areas, such as Sierra y Cañon de Jimulco, Tomás Garrido, 026 Bajo Río San Juan, Zapalinamé, Zapalinamé, and Cumbres de Monterrey Restoration Zones for the conservation of the species under local climate change scenarios. In addition, new areas in the northwest and center of Coahuila could be used to establish new protected areas for this economically important species.