Summer drought influence on CO2 and water fluxes of extensively managed grassland in Germany
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Contributors
Abstract
Net ecosystem CO2 exchange (NEE) and water fluxes of extensively managed grassland in Germany were measured in a dry year, 2003 and a normal year, 2004 using eddy covariance. Empirical descriptions of canopy capacities (light utilization efficiency and canopy capacity for maximum carboxylation) and inherent water use efficiency (IWUE*) were computed to indicate the grassland's response to environmental and management conditions. Compared with 2004, 2003 was characterized by a 2.5°C rise in summer mean temperature and an annual precipitation deficit of 286mm, which was almost one-third below the average precipitation of the normal year 2004 and the long-term annual average (1959-2005). Annual net water balance (precipitation minus evapo-transpiration) in 2003 and 2004 were 85mm and 361mm, respectively. Slightly higher IWUE* in 2003 indicates the grassland's sensitivity to drought. The grassland provided an annual gross primary production (GPP) and ecosystem respiration (Reco) of 1022 and 728gCm-2 respectively in 2003, as compared to their corresponding values of 1233 and 973gCm-2 in 2004. Drought-induced biomass senescence caused GPP reduction in 2003, which in turn affected the ecosystem respiration. Light explained more than 80% of NEE variability during canopy development and as a result, annual NEE in 2003 and 2004 were -295 and -260gCm-2, respectively. Taking into account the exported carbon by biomass harvest, we calculated net biome productivity (NBP) of -113gCm-2yr-1. We conclude that this managed grassland acted as a moderate carbon sink, despite the difference in environmental and management conditions.
Details
Original language | English |
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Pages (from-to) | 67-76 |
Number of pages | 10 |
Journal | Agriculture, Ecosystems and Environment |
Volume | 141 |
Issue number | 1-2 |
Publication status | Published - Apr 2011 |
Peer-reviewed | Yes |
External IDs
Scopus | 79954631019 |
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ORCID | /0000-0003-2263-0073/work/163766013 |
Keywords
Keywords
- Ecosystem respiration, Evapo-transpiration, Gross primary production, Light response, Net CO exchange, VPD, Water deficit