Controls of spatio-temporal patterns of soil respiration in a mixed forest

Introduction Patterns of soil respiration (R s ) are heterogeneous on temporal and spatial scale. The most important controlling factors of soil respiration are microclimatic conditions such as soil temperature and moisture. However, a strong pronounced seasonality shifts R s patterns from temperature to moisture-controlled regimes. Rarely investigated patterns are time-lagged effects prior to R s measurements and influences of trees in mixed forests on large spatio-temporal scales. Material and Methods We investigated R s over two years on a weekly to fortnightly measurement rhythm at an approximately 1 ha area in a mixed forest on 35 predefined locations using the common chamber technique. Analysis was derived using meteorological data and a tree species map. Results By tendency, R s decreased with increasing distance to the tree and we observed significantly higher R s in broadleaf patches compared to coniferous and mixed patches during the summer season (+27 %, +18 %, respective). Our data confirmed soil temperature and moisture as important controlling variables. Yet, our results highlight an additional predictor explaining a higher proportion in variability: the vapour pressure in the atmosphere. In contrast to soil temperature and moisture this predictor was able to track a collapse in R s due to drought and increases following rewetting. Conclusion We conclude that meteorological conditions might be valuable indicators for CO 2 emissions from forest soils. Tree species distribution explained partly the spatial patterns and hot spots of R s yet additional analysis of local soil properties will enhance our understanding of the soil plant interactions and the resulting R s .