Consequences of intense drought on CO2 & CH4 fluxes and evapotranspiration rates of the reed ecosystem at Lake Neusiedl

Activity: Talks and presentationsPoster presentationScience to Science

Description

Wetlands with reeds (Phragmites australis) are widely recognized as strong carbon (C) sinks due to the high productivity of reed and its fixation in the soil. Lake Neusiedl is an internationally important wetland (Ramsar, UNESCO World Heritage Site) that had been affected by droughts since mid-2015. However, the impact of drought on reed-dominated wetlands and the contribution of Central European reed ecosystems as a source of greenhouse gases (GHG) are not well understood. The aim of this multi-year study (mid-2018 to 2022) was to investigate the drought-influenced C & water fluxes and their drivers in the reed ecosystem of this subsaline lake. We used eddy covariance technique to quantify GHG exchange between reed ecosystem & atmosphere and vegetation indices to account for reed growth.

The results showed a 76% decrease in CH4 emissions from 9.2 g C m-2 a-1 (2019) to 2.2 g C m-2 a-1 (2022), mainly due to the falling water level and the associated drying out of the reed belt. Initially, net CO2 emissions decreased by 85% from 181 g C m-2 a-1 (2019) to 27 g C m-2 a-1 (2021), as the reed grew into formerly water-covered areas within the reed belt. In 2022, however, net CO2 emissions increased to twice the 2019 level due to the consequence of the sharp drop in sediment water content from 65 to 32 Vol-% in mid-2022.

Overall, drought led to a decoupling of the reed belt from the lake and turned the wetland into a strong C source.
Period12 Sept 2024
Event titleICOS Science Conference 2024
Event typeConference
LocationVersailles, FranceShow on map
Degree of RecognitionInternational