Forest soil respiration under climate changing

Soil respiration is a process of prime relevance for understanding the carbon cycle in forest ecosystems and for properly comprehending the role of forests in climate change mitigation. The process is divided into two components: (i) autotrophic soil respiration, i.e. the efflux of CO2 from the respiration of tree roots, and (ii) heterotrophic soil respiration, i.e. the efflux of CO2 due to respiration of soil microorganisms. A third component, the respiration of mycorrhizae, is still debated and it is not yet clear whether it should be accounted for in autotrophic or heterotrophic soil respiration, respectively, or whether it should be treated as a third component. The rate of soil respiration is controlled by environmental factors. Expectedly, the strongest driver is soil temperature, followed by soil moisture. The relevance of either factor depends on site properties. Two papers are reinforcing this view. An asset of the paper compilation is the collection of case studies where other factors besides temperature and soil moisture are evidently greatly affecting the rate of soil respiration. The characteristics of the forest stand such as tree density, stand age, and tree species and additional soil properties such as aggregate stability are influencing soil respiration. The book gives guidance on the current state of knowledge and helps identifying knowledge gaps for future research endeavours