Assessment of soil carbon stocks after afforestation in England and Wales

Summary

This project was commissioned by the Forestry Commission to provide more robust evidence of soil carbon change and sequestration potential after afforestation. A soil resurvey was carried out by Cranfield University on selected sites from the Soil survey of England and Wales which have changed land use to forestry in the past 30-40 years. Results, bringing together soil and forestry information in order to calculate the change and rates of changes of soil carbon and other soil properties due to forest creation, will contribute to the evaluations of overall GHG mitigation potential of forestry and the Woodland Carbon Code.

Research objectives

Cranfield University has an inventory of sites where soil samples were taken from each soil horizon down to the parent material and analysis of basic soil properties was conducted as part of the National Soil Survey of England and Wales between the 1960s and 1980s. The aims of the present study were to:

  • Select suitable sites for re-sampling, based on afforestation since previous sampling (a total of 20 sites),
  • re-visit sites and sample all soil profiles, to determine soil pH, carbon and nitrogen stocks of each horizon and of archived samples.

Results

This research provided valuable information guiding the likely direction and rate of change of soil C stocks due to afforestation. Trends indicated that afforestation was neutral or slightly positive for soil C sequestration when sandy soils like podzols are converted to conifer forestry. Increasing surface organic layers under afforestation provided the highest C stock increase under all forest types, on all soil types and from all previous land uses, compared to mineral soils (where the main C losses were observed).

Full details and results of this project will be available soon.

Status

A new feasibility study has been commissioned to create a database of all data available from experiments and soil surveys and resurveys aiming at afforestation impacts on soil carbon stocks.

Contact

Dr Elena Vanguelova

Funders and partners

The research was undertaken in collaboration with NSRI, Cranfield University and Forestry Commission.

Forestry Commission policy

At the core of the Government's policy on sustainable forest management is the need to safeguard soil and water resources. Human actions, from local scale forest operations to international scale climate change and air pollution may compromise forest soil sustainability with consequential impacts on the freshwater environment. Poorly planned and managed forests can severely degrade soil and water resources, making forests more vulnerable to climate change. Good management, in contrast, seeks to maintain and enhance the natural protective functions of forests and the benefits they provide for society, including carbon sequestration, clean water and reduced flood risk. The overall objective of this programme is to evaluate through measuring, modelling and mapping the impacts of forests, woodlands and management practices on soil and water resources under a changing climate and changing pollutant emissions. It also aims to quantify the benefits of woodland creation for soil, water and flood management and evaluate the role of woodland in integrated catchment management. The findings will improve our understanding of the nature of these impacts and be used to help develop practices and guide future policy to secure the soil and water services that underpin the multiple benefits provided by forests.