期刊
BIOGEOCHEMISTRY
卷 97, 期 1, 页码 7-19出版社
SPRINGER
DOI: 10.1007/s10533-009-9297-9
关键词
Carbon; Climate change; Dissolved organic carbon; Soil organic matter; Soil respiration; Stable isotopes; Temperature; Treeline
资金
- Velux foundation and a French ANR-biodiversite''
- Swiss National Science Foundation (SNF) [315200-116861]
Climatic warming will probably have particularly large impacts on carbon fluxes in high altitude and latitude ecosystems due to their great stocks of labile soil C and high temperature sensitivity. At the alpine treeline, we experimentally warmed undisturbed soils by 4 K for one growing season with heating cables at the soil surface and measured the response of net C uptake by plants, of soil respiration, and of leaching of dissolved organic carbon (DOC). Soil warming increased soil CO2 effluxes instantaneously and throughout the whole vegetation period (+45%; +120 g C m y(-1)). In contrast, DOC leaching showed a negligible response of a 5% increase (NS). Annual C uptake of new shoots was not significantly affected by elevated soil temperatures, with a 17, 12, and 14% increase for larch, pine, and dwarf shrubs, respectively, resulting in an overall increase in net C uptake by plants of 20-40 g C m(-2)y(-1). The Q (10) of 3.0 measured for soil respiration did not change compared to a 3-year period before the warming treatment started, suggesting little impact of warming-induced lower soil moisture (-15% relative decrease) or increased soil C losses. The fraction of recent plant-derived C in soil respired CO2 from warmed soils was smaller than that from control soils (25 vs. 40% of total C respired), which implies that the warming-induced increase in soil CO2 efflux resulted mainly from mineralization of older SOM rather than from stimulated root respiration. In summary, one season of 4 K soil warming, representative of hot years, led to C losses from the studied alpine treeline ecosystem by increasing SOM decomposition more than C gains through plant growth.
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