Authors: Margit von Lützow Ingrid KögelKnabner
Publish Date: 2009/10/30
Volume: 46, Issue: 1, Pages: 1-15
Abstract
Soil organic matter SOM represents one of the largest reservoirs of carbon on the global scale Thus the temperature sensitivity of bulk SOM and of different SOM fractions is a key factor determining the response of the terrestrial carbon balance to climatic warming We condense the available knowledge about the potential temperature sensitivity and the actual temperature sensitivity of decomposition in situ which ultimately depends on substrate availability We review and evaluate contradictory results of estimates of the temperature sensitivity of bulk SOM and of different SOM fractions The contradictory results demonstrate a need to focus research on biological and physicochemical controls of SOM stabilisation and destabilisation processes as a basis for understanding strictly causal relationships and kinetic properties of key processes that determine pool sizes and turnover rates of functional SOM pools The current understanding is that temperature sensitivity of SOM mineralisation is governed by the following factors 1 the stability of SOM 2 the substrate availability which is determined by the balance between input of organic matter stabilisation and mineralisation of SOM 3 the physiology of the soil microflora its efficiency in substrate utilisation and its temperature optima and 4 physicochemical controls of destabilisation and stabilisation processes like pH and limitation of water oxygen and nutrient supply As soil microflora is functionally omnipotent and most SOM is of high age and stability the temperature dependence of stable SOM pools is the central question that determines C stocks and stock changes under global warmingWe thank the two reviewers as well as the editor for their constructive and very helpful advice This study was financially supported by the Federal Ministry of Education and Research within the project ‘Potential analysis of modifications of land use systems and their biogeochemical cycles for the attainment of the greenhouse gas reduction goals’ FKZ 01LG0801A
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