2 results
13 - The role of soils in the Kyoto Protocol
- Edited by Werner L. Kutsch, Max-Planck-Institut für Biogeochemie, Jena, Michael Bahn, Leopold-Franzens-Universität Innsbruck, Austria, Andreas Heinemeyer
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- Book:
- Soil Carbon Dynamics
- Published online:
- 11 May 2010
- Print publication:
- 07 January 2010, pp 245-256
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Summary
INTRODUCTION
The world's soils contain approximately 1500 Pg (1 Pg = 1 Gt = 1015 g) of organic carbon (Batjes, 1996), roughly three times the amount of carbon in vegetation and twice the amount in the atmosphere (IPCC, 2001; Denman et al., 2007). The annual fluxes of CO2 from atmosphere to land (global net primary productivity, NPP) and land to atmosphere (respiration and fire) are of the order of 60 Pg C y−1 (IPCC, 2000b). During the 1990s, fossil fuel combustion and cement production emitted 6.4 ± 1.3 Pg C y−1 to the atmosphere, while land-use change emitted 1.6 ± 0.8 Pg C y−1. Atmospheric carbon increased at a rate of 3.2 ± 0.1 Pg C y−1, the oceans absorbed 2.3 ± 0.8 Pg C y−1 and there was an estimated terrestrial sink of 2.6 ± 1.3 Pg C y−1 (Schimel et al., 2001; Denman et al., 2007). The amount of carbon stored in soils globally is therefore large compared to gross and net annual fluxes of carbon to and from the terrestrial biosphere, and the pools of carbon in the atmosphere and vegetation. Because of this, increasing the size of the global soil carbon pool by even a small proportion has the potential to sequester large amounts of carbon, and thus soils have an important role to play in mitigating climate change.
Human intervention, via cultivation and disturbance, has decreased and still is decreasing the soil carbon pools relative to the store typically achieved under native vegetation.
12 - Modelling soil carbon dynamics
- Edited by Werner L. Kutsch, Max-Planck-Institut für Biogeochemie, Jena, Michael Bahn, Leopold-Franzens-Universität Innsbruck, Austria, Andreas Heinemeyer
-
- Book:
- Soil Carbon Dynamics
- Published online:
- 11 May 2010
- Print publication:
- 07 January 2010, pp 221-244
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- Chapter
- Export citation
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Summary
INTRODUCTION
The need for models of soil organic matter (SOM) turnover is similar to the need for many models of environmental processes: they are used to better understand processes; extrapolate or interpolate experimental results in time, space and to different environmental conditions; and to investigate scenarios and hypotheses that are beyond the realm of experimental work. As a result of this, a wide variety of SOM models have been developed, differing in their formulation and purpose. There are a number of approaches to modelling SOM turnover including process-based multi-compartment models, models that consider each fresh addition of plant debris as a separate cohort that decays in a continuous way, and models that account for carbon and nitrogen transfers through various trophic levels in a soil food web. This chapter aims to give a broad overview of currently available SOM models, highlighting areas of model application, identifying strengths and weaknesses and future directions for model development. We focus on two of the most widely used SOM models, RothC and CENTURY, to provide detailed case studies of model formulation, development and application.
SOIL ORGANIC MATTER MODELS
There are several sources of metadata and information on SOM models. CAMASE (Plentinger and Penning de Vries, 1996) contains 98 agro-ecosystems models having soil components, and the Global Change and Terrestrial Ecosystems Soil Organic Matter Network (GCTE-SOMNET) database (Smith et al., 1996a, 1996b: online at http://saffron.rothamsted.bbsrc.ac.uk/cgi-bin/somnet/) contains metadata on over 30 current operational SOM models. Several authors have previously reviewed SOM models extensively.
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