Spatio-temporal modelling of stable isotopes in tree mediterranean species (quercus ilex l. And pinus halepensis mill.)a climatic and ecophysiological view

Abstract

Abstract Trees hold important secrets that may be essential in order to face the unprecedented current environmental challenges. The basis of this thesis is to use a combination of modern tools such as stable isotopes, Geographical Information Systems (GIS), Point Process statistics to retrieve climatic and ecophysiological information from forests at different spatial and temporal scales. We focus on two typical coexisting Mediterranean species: holm oak (Quercus ilex L.) and Aleppo pine (Pinus halepensis Mill.). At the regional scale: we generated carbon isotope (D13C) landscapes (isoscapes) of each species, later converted to annual precipitation maps: and we also showed that in Aleppo pine, annual precipitation drives D13C, RG and NDVI, but the three variables hold complementary information. At the local scale, we focus on a mixed forest stand in which both species coexist. By combining water isotopes and point process statistics, we could interpret tree-to-tree interactions in terms of water use (including seasonal variation).We found evidences of a dynamic niche segregation.