Response of Growth to Climate within Oaks of the World Heritage Site of Prussian Gardens

From a general point of view, it is worth to study the degree of species ability to adapt or resist to the changing environmental conditions.From a historical point of view, additional research on tree Abstract: Trees constitute the basis for structure and convey the particular impression of most historic gardens and parks.In the World Heritage property 'Palaces and Parks of Potsdam and Berlin' (Germany) oaks are among the most abundant tree species and can be seen as key species.Questions about exact age, extent and time of environmental influences and impact of extreme weather events still remain unanswered.Against this background, this study tries to get answers about the reaction of these oaks to climatic conditions at three sites, and about the link between vitality and tree-ring growth with a dendrochronological approach.A correlation analyzes and moving correlations gave insight in climate-growth relationships and their stability.Growth reactions were also evaluated in single years by pointer year analyses and superposed epoch analyses (SEA).The oak trees show declining growth trends which can be interpreted as typical sign of the old stage of trees and that are not necessarily linked to changing climatic conditions.However, our results highlight the significance of adequate precipitation sums in previous year's July and September and from current May to July for xylogenesis.This result is confirmed by the correlation analyzes to ground-water table and a drought index as well as by the pointer year analyses and the SEA.The climate-growth correlations show instability in many months of previous and current year over recent decades.The results of the present study show strong site-specific drought sensitivity for Quercusthat is strongly correlated with soil moisture conditions and precipitation.