Drought sensitivity of three co-occurring conifers within a dry inner Alpine environment.

We applied dendroclimatological techniques to determine long-term stationarity of climate-growth relationships and recent growth trends of three widespread coniferous tree species of the central Austrian Alps, which grow intermixed at dry-mesic sites within a dry inner Alpine environment (750 m asl). Time series of annual increments were developed from > 120 mature trees of and . Calculation of response functions for the period 1911 - 2009 revealed significant differences among species in response to climate variables. While precipitation in May - June favoured radial growth of and growth mainly depended on April - May precipitation. growth was most sensitive to May - June temperature (inverse relationship). Moving response function coefficients indicated increasing drought sensitivity of all species in recent decades, which is related to a decline in soil moisture availability due to increasing stand density and tree size and higher evapotranspiration rates in a warmer climate. While recent trend in basal area increment (BAI) of distinctly declined implying high vulnerability to drought stress, moderately shade-tolerant showed steadily increasing BAI and quite constant BAI was maintained in drought adapted , although at lowest level of all species. We conclude that synergistic effects of stand dynamics and climate warming increased drought sensitivity, which changed competitive strength of co-occurring conifers due to differences in inherent adaptive capacity.