Abstract
Background Defra require a literature review to collate published evidence on a) the causes of C loss from soils and b) the fate of the lost C. The purpose of this review is to inform a policy workshop which will be: i) assessing the significance of the work to date in policy terms; and ii) defining the next steps for evidence gathering, policy development and stakeholder engagement (both input and potential funding). Objectives This report will be set out in 3 parts to provide a description of the scientific data available, remaining evidence gaps and significant questions still to be answered: 1. Technical review of the literature 2. Non-technical summary 3. List of questions to aid discussion in a policy workshop Proposal The first part of the report will collate the current scientific literature with regard to a) the causes of carbon losses from soils and b) the fate of the carbon once it has been lost from the soil pool. Part a) will concentrate initially on global carbon sinks, including a description of the various forms and concentrations of carbon present and the flux between sinks, in particular losses of carbon from soils. The main causes of a net release of carbon from soils will be reviewed: climate change (e.g. temperature, precipitation, seasonality) and changes in land practices, (e.g. clearing and cultivation, grazing and harvesting of forests). Part b) will concentrate on the fate of carbon once it is lost from the soil in its various forms. The most accurate estimates of global terrestrial carbon fate consider both the processes involved and the spatial distribution of soils and vegetation. The second part will be an easily understandable, non-technical summary of the technical review from part one. This 5 page document will be written for a non-expert end-user audience for use at a Defra workshop following submission of the technical review. The third part will list a number of questions that have been raised by the technical review, which will aid discussion in the policy workshop and facilitate the design of the programme. These will consider the relevance of options for control of soil C loss (both through management, policy and other); and the certainty of data collated to date.
United Kingdom