Journal article
The response of dissolved organic carbon (DOC) and the ecosystem carbon balance to experimental drought in a temperate shrubland
Centre for Ecology and Hydrology1
Ecosystems, Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark2
Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark3
Risø National Laboratory for Sustainable Energy, Technical University of Denmark4
Climate change has been proposed as a driver of carbon (C) loss from the large pool of C held in soils. Aqueous (dissolved organic carbon, DOC) and gaseous (soil respiration or net ecosystem CO2 exchange) forms of C loss from soils have been considered. Under some climate change scenarios, gaseous emissions of C have been predicted to result in terrestrial ecosystems becoming a net source of C by 2050.
Indeed, both forms of C loss have been linked to climate-related changes, such as warming and/or changes in precipitation. In our field-based drought manipulation experiment on an upland moorland in northeast Wales, we have carried out an annual drought treatment for 8 years, reducing levels of annual rainfall by 23% on average (1999–2007) through the use of automated roofs, which prevent rain falling on experimental plots between June and September annually.
Following 5 years of repeated summer drought, there was a 26% increase in concentrations of DOC in soil water in the mineral soil in the drought plots and this further increased to 52% after 8 years. A similar pattern was not observed in the organic soil horizons. Despite higher DOC concentrations in the mineral soil horizon, decreased drainage of water from the drought-treated soils resulted in an overall decrease of 9% in total DOC export.
Calculating the carbon (C) balance for the below-ground component of the ecosystem reveals that DOC represents 3% of gross C export. Previous studies at the site have demonstrated large increases in soil respiration resulting from the repeated drought treatment. By including data presented here with other C fluxes and pool measurements from the site, we demonstrate that soil carbon is accumulating by 126 g C m−2 year−1 in the control plots, but decreasing by 18 g C m2 year−1 in the drought plots.
The repeated drought treatment has thus resulted in the ecosystem switching from a net sink for C into a net source.
| Language: | English |
|---|---|
| Year: | 2010 |
| Pages: | 697-709 |
| ISSN: | 13652389 and 13510754 |
| Types: | Journal article |
| DOI: | 10.1111/j.1365-2389.2010.01276.x |
