Strict-sense local seed-sourcing strategy (SSL) was defined for each deployment zone as the use of autochthonous populations pertaining to the same region of provenance for each species. Wide-sense local seed-sourcing strategy (WSL) was defined as the use of the pool of regions of provenance with a suitable climatic niche in each zone. Niche modelling was used to obtain the climate-predicted distribution of the species based on the actual presence and the climate (assuming no restrictions to dispersal and no human influence). Nine climatic variables were considered: mean annual (P), winter (WP), and summer (SP) precipitation, mean annual temperature (T), minimum temperature of the coldest month (MTC), maximum temperature of the warmest month (MTW), growing degree days (t>5°) (DD), total number of months under frost (t<0º) (F), duration of the drought period in months (P<2T) (DP). These variables have been used for modelling niche distribution of different forest species in Spain. A similarity index was obtained based on the Mahalanobis climatic distance (using the same set of climatic variables that in the niche modelling estimation, among the points with presence of the region of provenances and the points of each deployment zone. Based on this similarity the regions of provenance were classified as suitable or not for each deployment zone.

This research was supported by the Project AEG 17-048 established in the frame of the measure 15.2 "support to the conservation and use of forest genetic resources" and under Regulation (EU) No 1305/2013 of the European Parliament and of the Council of 17 December 2013 on support for rural development by the European Agricultural Fund for Rural Development (EAFRD) with 75% co-financing. This study was funded by the European Union Horizon 2020 research and innovation programme under grant agreement No 773383 (B4EST project), and the Ministry of Science (RTI2018-094691-B-C32)