Modeling current distribution of Spanish Quercus pyrenaica forests using climatic parameters

The geographical distribution of Quercus pyrenaica forests in the Iberian Peninsula is analysed from a climatic point of view. 438 phytosociological releves were collected and 28 climatic parameters were derived from their geographical features using the EST-CLIM model. The objectives of our work were to define the main climatic characteristics that explain the particular distribution pattern of Quercus pyrenaica forests in Spain and to obtain the climatic envelopes that best define these vegetation types. For this purpose, four floristic and their corresponding climatic matrices were analysed by means of Canonical Correspondence Analysis (CCA). Results show the importance of some climatic features that define the Mediterranean climate: summer dryness and winter precipitation, both of which serve to separate some types of forest. It is the case of Adenocarpo-Quercetum pyrenaicae and Berberido-Quercetum in southern Spain or Festuco-Quercetum and Luzulo-Quercetum, in the center of the Iberian Peninsula, which are separated in terms of summer dryness. Luzulo baeticae-Quercetum is well separated from the other two associations it was compared with (Arbuto-Querceturn and Sorbo-Quercetum) by winter precipitation. Exposure also plays an important role in some ranges such as the Sierra Madrona where a different type of forest appear in warmer or cooler exposures. Finally, other phytosociological adscriptions of releves to a type of association presented problems due to a very similar floristic composition, as is the case of Genisto falcatae-Quercetum and Holco-Quercetum. Regarding the differences between Eurosiberian forests and northern Mediterranean ones, separation resulted difficult since some of them (Melampyro-Quercetum) showed a not very clear separation from those Mediterranean forest they were compared (Genisto falcatae-Quercetum, Holco-Quercetum and Linario triornithophorae-Quercetum), in terms of the climatic variables analysed, however they showed a very different floristic composition.