Tree growth responses to different environmental conditions

Increasing frequency and intensity of droughts affect forest ecosystems. There are already higher rates of tree mortality and forest drought-induced dieback. Since climate change affects the soil conditions, the precipitation rates and the growth seasons, it is expected that trees will develop acclimation and adaptation strategies in order to maintain vigor. Since the two most important reasons of mortality are carbon starvation and hydraulic failure, adjustments in physiological traits are expected to be related to the maintenance of the tree carbon and water balances. This thesis focused on understanding how trees respond under different environmental conditions (e.g. wet vs dry) both at the intraspecific and interspecific level. The conducted studies focused on biomass allocation, xylem and phloem anatomies of stem and branches, xylem anatomy of leaves, plant hydraulics, and wood density. Mostly, data from personal measurements were used, but also published data to compare the results. The aim was to understand which structural traits are linked to the acclimation and adaptation strategies of trees and how. The structure of the thesis is: (i) general introduction, (ii) five main chapters based on different studies, (iii) one main chapter describing in short three more studies, (iv) overall conclusion, (v) additional information for each of the main chapters (if applicable), (vi) acknowledgments, (vii) anatomical images for some chapters, (viii) literature cited listed per chapter.