|Brumme, R; Borken, W; Prenzel, J: Soil respiration in Brumme, R. and Khanna, P.: Ecological Studies, Functioning and Management of European Beech Ecosystems, Springer, 208, 337-352 (2009)|
The recent discussion about global climate change has intensified the role of soils which may act as a sink or a source of carbon under changing environmental conditions (Schulze 2000; Valentini 2003). A decrease of organic carbon by 10% in the whole world soils would be equivalent to all the anthropogenic CO2 emitted over 30 years (Kirschbaum 2000). It is generally argued that with an increase in global warming both net primary production (NPP) and decomposition of soil organic carbon (SOC) will increase (Kirschbaum 1995, 2000). The issue is which of these processes are stimulated by increasing temperature. Soil respiration includes heterotrophic respiration and autotrophic respiration, and their temperature sensitivities will largely determine the effect of a warmer world on net carbon flux between soils and atmosphere (Boone et al. 1998). However, there is increasing evidence that soil respiration is determined more by carbohydrate supply than by temperature (Ho¨gberg et al. 2001). A reliable technique of measuring respiration that provides temporal and spatial variations in the soil and autotrophic respiration is required for assessing ecosystem levels effects. Another issue is whether forest soils, which have been affected by acid and nitrogen deposition or liming, will react differently to changing climate. We will therefore consider: (1) methodological aspects of assessing soil respiration by using chambers, (2) ways to obtain reliable flux estimates with consideration of temporal and spatial variations, (3) evaluation of annual CO2 fluxes from three beech forest soils, (4) the contribution of autotrophic and heterotrophic respiration to soil respiration, (5) the temperature sensitivity of autotrophic respiration and heterotrophic respiration, and (6) the effect of liming and N-fertilisation and stand harvesting by the formation of small gaps on soil respiration.