Abstract. For central Europe in addition to rising temperatures an increasing
variability in precipitation is predicted. This will increase the probability
of drought periods in the Alps, where water supply has been sufficient in
most areas so far. For Alpine grasslands, community-specific imprints on
drought responses are poorly analyzed so far due to the sufficient natural
water supply. In a replicated mesocosm experiment we compared
evapotranspiration (ET) and biomass productivity of two differently
drought-adapted Alpine grassland communities during two artificial drought
periods divided by extreme precipitation events using high-precision small
lysimeters. The drought-adapted vegetation type showed a high potential to
utilize even scarce water resources. This is combined with a low potential to
translate atmospheric deficits into higher water conductance and a lower
biomass production as those measured for the non-drought-adapted type. The
non-drought-adapted type, in contrast, showed high water conductance
potential and a strong increase in ET rates when environmental conditions
became less constraining. With high rates even at dry conditions, this
community appears not to be optimized to save water and might experience
drought effects earlier and probably more strongly. As a result, the water
use efficiency of the drought-adapted plant community is with
2.6 gDW kg−1 of water much higher than that of the
non-drought-adapted plant community (0.16 gDW kg−1). In
summary, the vegetation's reaction to two covarying gradients of potential
evapotranspiration and soil water content revealed a clear difference in
vegetation development and between water-saving and water-spending strategies
regarding evapotranspiration.
Exploring the growth response of Norway spruce (Picea abies) along a small-scale gradient of soil water supply
