Seminar: Alice Orme
- Date: Jul 7, 2022
- Time: 02:00 PM - 03:00 PM (Local Time Germany)
- Speaker: Alice Orme
- Abteilung Biogeochemische Prozesse
- Location: Max-Planck-Institut für Biogeochemie
- Room: Hörsaal (C0.001)
Drought is an ever-increasing threat; its negative effects on ecosystems and their functioning directly impact our food security. It is therefore critical to understand how ecosystems respond to drought. Many ecosystem functions depend on plant-soil interactions and are mediated by dissolved organic molecules, which are then recorded in the dissolved organic matter (DOM) that leaches from plants and soils. In particular, DOM properties during and after rewetting can reveal if and how ecosystems are affected by drought. We therefore investigated the concentration of DOM in four different plant communities on sandy soils in Germany over three years that differed in drought intensity, including the extreme 2018 drought. We also analysed the molecular composition of DOM using ultrahigh-resolution mass spectrometry to identify the matter sources during the rewetting period. Linear mixed effect models revealed that different years had significantly different DOM concentrations. DOM concentration in soil leachate was greatest during a normal year, but was significantly reduced during a drought year. This suggests that DOM release is stimulated during a normal year, however, drought reduces DOM release. In addition, the characteristic increase in DOM concentration that is usually observed following a rewetting event was suppressed during the drought year. Molecular composition analysis of the DOM present during the rewetting period revealed an initial release of plant-derived matter, and the degradation of this matter over time. Our findings indicate that the initial release of plant-derived matter into soil leachate might be crucial for the ability of ecosystems to quickly recover from drought. Drought may interrupt plant functioning to the point of preventing the accumulation and subsequent release of plant-derived matter during drought, and therefore hamper ecosystem recovery.
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