Straits forest floor carbon dioxide measurements


This project measures the carbon dioxide (CO2) released from the forest floor at the Straits Inclosure in Alice Holt Forest. This work supports our research into understanding forest carbon balances and the effects of woodland management.

Here is a short video summarising this work.

Research objectives

  • Quantify the CO2 release from the forest floor of a temperate oak forest in southern England (including both the soil and leaf litter components).
  • Understand the effects of environmental change and weather on the CO2 release from the forest floor.
  • Provide data on forest floor CO2 release for woodland carbon balance modelling (for example, to assess the possible climate change impacts).

Results so far

FR straits li8100 soil co2 chamberTwo sets of measurements are collected in this project. At five points in the forest the soil CO2 release from the forest soil (without leaf litter) is measured. From a further five points the CO2 from the combined soil and leaf litter is measured. These measurements are taken weekly using a LI-COR Instruments LI-8100A analyser and 20 cm survey chamber.

The results from this long-term monitoring of forest soil CO2 fluxes have shown that there is a distinct annual cycle. Soil CO2 fluxes are larger in the summer and smaller in the winter, probably driven by the temperature and soil moisture, and by changes in root activity.

Previous studies at this site have also measured the CO2 released from the forest floor. Heinemeyer et al. (2012) found that the annual rate of CO2 released was 740 ± 43 g C m-2 yr-1 and Yamulki & Morison (2017) reported 894 g C m-2 yr-1.

The gross rate at which the forest in the Straits Inclosure took up CO2 (1999-2010) was 2034 ± 145 g C m-2 yr-1. In the same period, the rate of CO2 released by the Straits Inclosure  was 1548 g C m-2 yr-1(Wilkinson et al., 2012). The previous studies have therefore shown that the CO2 released from the soil is equivalent to 48-58% of the total CO2 leaving this forest.straits soil co2 flux

The graph above shows the mean CO2 released from the soil (blue) and the soil and litter combined (green), as measured by this project since 2013. Error bars are ± 1 standard error.

The current project is continuing to add measurements to our dataset. These measurements, in addition to those from the eddy covariance tower, will help improve our understanding of the amount of CO2 coming from the soil and what drives the processes that produce it.


Heinemeyer, A., Wilkinson, M., Vargas, R., Subke, J.-A., Casella, E., Morison, J.I.L. and Ineson, P. (2012). Exploring the "overflow tap" theory: linking forest soil CO2 fluxes and individual mycorrhizosphere components to photosynthesis. Biogeosciences 9: 79-95.

Wilkinson, M., Eaton, E.L., Broadmeadow, M.S.J. and Morison J.I.L. (2012). Inter-annual variation of carbon uptake by a plantation oak forest in southern England. Biogeosciences 9: 5373-5389.

Yamulki, S. and Morison, J.I.L. (2017). Annual greenhouse gas fluxes from a temperate deciduous oak forest floor. Forestry. doi:10.1093/forestry/cpx008.


This project started in 2013 and is ongoing.


Ed Eaton

Funding and Partners

This project is part of the Assessung Resilience research programme.

Forestry Commission Policy

The project supports FC policy by investigating how forests help us address climate change, and policies on sustainable forest management. This includes those addressing protecting forests and the ecosystem services they provide, such as carbon storage in the soils, carbon sequestration in growing trees, and wood provision for timber and biomass markets. The work addresses knowledge gaps about quantifying the carbon balance of forests and the effect of disturbance, and helps underpin the values used in the Woodland Carbon Code