Estimating potential C-sequestration rates under bioenergy crops

Project Contact

Robin Matthews, Macaulay Institute.
Shibu Ebrahim Muhammed, Macaulay Institute.

Project Summary

Bioenergy crop plantations are being established to mitigate net CO2 emissions in accordance with UK commitments to the UN Kyoto Protocol on Climate Change. In addition to the provision of a ‘carbon neutral’ fossil fuel replacement energy source, bioenergy plantations may also contribute to the mitigation of net CO2 emissions by enhancing sequestration of C in the underlying soils. In this project, we use modeling approaches o evaluate the potential for soil C sequestration in various bioenergy crops in the UK.

To do this, we are developing a simple model to account for the major flows of C in such crops. Inputs of C into the soil can arise from decomposition of canopy litter and structural roots, and from fine root turnover, all of which are influenced by the growth rate of the stand. Losses of C from the soil are due to microbial respiration as organic material is decomposed.

Initial work has shown that, in England, willow and Miscanthus bioenergy stands have substantial potential to sequester C, possibly more than that which would occur under regenerating natural woodland. For a soil with defined characteristics, the rate of C sequestration is directly proportional to the rate of input of C to the system. Thus, due to its high C input from senesced leaves, Miscanthus, in particular, could accumulate relatively high amounts of C in the soil.

The current work is evaluating these findings under Scottish conditions.

Publications

1. Grogan, P. & Matthews, R.B., 2002. A modelling analysis of the potential for soil carbon sequestration under short rotation coppice willow bioenergy plantations. Soil Use and Management 18:175-183.
2. Matthews, R.B. & Grogan, P., 2001. Potential C-sequestration rates under short-rotation coppiced willow and Miscanthus biomass crops: a modelling study. Aspects Appl. Biol. 65:303-312.