Controls of spatio-temporal patterns of soil respiration in a mixed forest
IntroductionPatterns of soil respiration (Rs) are heterogeneous on spatio-temporal scales. The best studied controlling factors of Rs are microclimatic conditions such as soil temperature and moisture. However, a strong pronounced seasonality shifts Rs patterns from temperature to moisture-controlled regimes. Hereby, lag effects and influences of trees in mixed forests on large spatio-temporal scales are rarely investigated. Material and MethodsWe investigated Rs over two years on a weekly to fortnightly measurement frequency at a 1 ha area in a mixed forest on 35 predefined locations using open bottom chambers. Analysis was derived using downscaled meteorological data and a tree species map. ResultsOur data confirmed soil temperature and moisture as important variables which explained up to 72% in variability. Yet, our results revealed an additional predictor: the atmospheric vapour pressure. Together with seasonality and the vapour pressure deficit, 84% in variability could be explained. Additionally, the predictors traced a decrease in Rs due to drought and an increase due to rewetting. By tendency, Rs correlated negatively with distance to the tree and Rs was significantly higher in broadleaf patches compared to coniferous and mixed patches during the summer seasons. ConclusionWe conclude that meteorological conditions might serve as valuable predictors for CO2 emissions from forest soil. This enables upscaling of Rs given the dense availability of meteorological data. Tree species distribution partly explained the spatial patterns of Rs. However, a detailed analysis of local soil properties would enhance our understanding of the interactions between soils, plants and the atmosphere.