期刊
BIOGEOSCIENCES
卷 8, 期 9, 页码 2729-2739出版社
COPERNICUS GESELLSCHAFT MBH
DOI: 10.5194/bg-8-2729-2011
关键词
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资金
- CARBOITALY (FISR, Italian Ministry of Research and Education)
- MIND [EVK2-CT-2002-00158]
- IMECC Integrated Infrastructure Initiative [026188]
- EU [017841, 226701]
Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20% reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10% v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130%, 26%, 58% and 220 %, respectively, as compared to the control. In contrast, the 20% reduction in throughfall (equivalent to 10% reduction in precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10% reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.
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