Post-drought rewetting triggers substantial K release and shifts in leaf stoichiometry in managed and abandoned mountain grasslands.
Van Sundert, K., V. Brune, M. Bahn, M. Deutschmann, R. Hasibeder, I. Nijs and S. Vicca. 2020.
Abstract
Background and aim - When soil is rewetted after drought, typically a transient pulse of
mineralization and other microbial processes occur. This "Birch effect" translates into a
temporarily elevated soil carbon dioxide efflux (SCE) and may alter nutrient availability. While
rewetting effects on SCE have been frequently studied, effects on soil nutrient supply have rarely been considered despite potential relevance for plant nutrition during post-drought recovery.
Methods - We investigated the magnitude of the post-drought rewetting effect on SCE, ion
exchange membrane-derived soil nutrient supply rates and leaf stoichiometry in a drought
experiment in the Austrian Alps. We conducted the experiment on a managed grassland (MG) and
a nearby abandoned grassland (AG).35
Results - Under drought, soil moisture depleted faster at MG than at AG. Upon rewetting, the SCE
pulse was significantly larger at MG than at AG, whereas N, P and K supplies were more strongly
stimulated at AG. A large, transient rewetting effect on soil K supply (MG: 363 ± 132%; AG:
821 ± 195%) was reflected in elevated K in leaves of Leontodon hispidus.
Conclusions - Rewetting can alter post-drought nutrient availability in mountain grasslands, with40
particularly pronounced effects on soil K supply.
Key Words
Birch effect, drying-rewetting, soil respiration, potassium, nutrients, subalpine grassland
