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The Teabag Index (TBI)


This project aims to create a world soil map of carbon decomposition to compare the effects of climate and climate changes on soil carbon decomposition rates. An innovative and cost-effective method to gather data on soil carbon decomposition is to bury two types of teabag (green and rooibos) in the soil and measure their mass loss over time. As they are composed of different material, the two types of tea have contrasting decomposition rates.

Research objectives

The results will allow us to construct a carbon decomposition curve and determine what is known as the ‘Teabag Index’ (TBI). Forest Research aim to provide soil decomposition data for more than 150 forest sites in the UK. Not only will Forest Research be able to contribute to the results of this global study, but the UK data will inform our own investigations into soil carbon decomposition related to soil type, forest type, management, climate and pollution deposition.


Teabags have been collected from more than 200 forest sites across the UK. Samples analysed and data has been prepared to be submitted to Swedish partners for inclusion into the World map of decomposition.


Dr Elena Vanguelova

Funders and partners

UK research is being undertaken by Forest Research’s Soil Sustainability Group as part of a global study led by Umea University and Utrecht University.

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.


What's of interest

Teatime4science Project Website

The Tea Bag Index – UK Blog

Soil changes under long-term woodland establishment
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Soil changes under long-term woodland establishment
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