The current situation and future perspectives of Quercus ilex and Pinus halepensis afforestation on agricultural land in Spain under climate change scenarios

Abstract

Between 1994 and 2017, 137,455 ha of agricultural land were afforested in Andalusia (Spain), using a great diversity of tree species, under the Common Agricultural Policy scheme. Quercus ilex and Pinus halepensis were the most used species. In view of the need to know the spatial distribution of survival according to the potential species habitat, the current survival was assessed under current and foreseeable future climate change scenarios, using ensemble species distribution models (SDMs). Predicted potential distributions together with 2009 survival data were used to predict the distribution of the survival rate of the two species. The set modelling approach gave very accurate results for the current potential distribution of Q. ilex (AUCtrain = 0.908, TSS = 0.647, Kappa = 0.647) and P. halepensis (AUCtrain = 0.983, TSS = 0869, Kappa = 0.868) and moderately accurate estimates of the distribution of the survival rate of Q. ilex and P. halepensis (RMSE = 0.23). It was found that 25–38% of the Q. ilex and P. halepensis plantations planted between 1993 and 2000 were established in the optimal area of occurrence (probability of occurrence > 70%), but only 12.3% (Q. ilex) and 22.9% (P. halepensis) presented simultaneously an acceptable survival rate (> 50%). In addition, the volume of the environmental space defined by Q. ilex decreased, while that defined by P. halepensis remained constant in future projections under climate change. The potential of SDMs to predict the survival rate distribution of Q. ilex and P. halepensis and to assess the future stability for each of these species has been confirmed. In the worst case, ~ 5% of Q. ilex and ~ 33% of P. halepensis of planted surface would withstand climate change.