Overview: Many European foresters are demanding for more data and description from the natural ecosystems, which are still remaining in Eastern countries. The better understanding of the tree growth and drought response of the trees in the natural forest will be supplied. We instaled dendrometer in 9 different locations in Mesocontinental scale in the primary spruce forest. The aim of the proposed study is to use dendrochronological approache to investigate how higher temperature / drought period affect the intra-annual tree growth of the trees from different social status in the natural spruce forest in central and eastern Europe. In particular we will investigate if between social status / age / sites there are differences in: i) timing and duration fo the growing season and quantifying its inpact on the tree ring formation; ii) tollerance to drought by evaluating the night refilling capacity in warm and dry period.This study will strongly complement the ongoing study on the tree life traits and disturbance dynamic of the natural forest, and will fill the missing gap of the studies on tree drought response from the eastern Europe (FPS COST Action FP1106, STReESS – Studying Tree Responses to extreme Events: a SynthesiS).