Michael Gross on how the Wytham Woods field station is helping monitor the threats to the world's forests from climate change.

Very early on a wintry November morning, I join a group of 12 bank employees at the University field station at Wytham going out into the woods. After a short walk, we come to the research plot, a 100 x 100-metre area where the volunteers from HSBC offices in the UK, Ireland, France, Poland and Malta investigate tree growth and the lives of the mammals inhabiting the forest.

This morning, there are 25 live traps to be emptied. Most of them contain wood mice who don't seem all that upset, having spent a cold night in the relative comfort of an insulated container with plenty of food. Jokes make the rounds that, after decades of research in this location the mice have probably learned to seek out the traps for easy food and shelter.

The volunteers measure the length of each animal they find in the traps, determine its species and sex, and weigh it with the help of a Pringles tube. They also check for signs of previous capture and mark any firsttime guests by clipping a few hairs from their fur. Finally, they release the animals close to the location where they were caught, so as not to upset their social lives.

The bankers work in three teams of two or three people, with one of the volunteers keeping records of all observations, and Dr Eleanor Slade of the University's Wildlife Conservation Research Unit (WildCRU) supervising the procedures and helping out here and there. By 10.30 am, they have emptied and reset all 25 traps, and liberated 20 wood mice and 1 common shrew. With frozen limbs, we return to the field station to warm up with tea and toast. Later in the day, the volunteers will turn their attention to measuring the diameters of the trees in the area, determining the tree species present, and collecting leaves from 1 x 1-metre nets set out to collect all litter.

But how and why did all these bankers from across Europe get to go to the woods to study the mice and the trees? Their work is part of a global network of Regional Climate Centres, set up by the international environmental charity Earthwatch (whose European HQ is located in Summertown), the bank HSBC, and the Smithsonian Tropical Research Institute, as part of the HSBC Climate Partnership.

Dr Dan Bebber, who holds a junior research fellowship at St Peter's College, oversees climate change research for Earthwatch. The idea, he explains, is to investigate the connection of forests to climate change around the world, including, in particular, the tropical regions, where too little data is available so far. Other Regional Climate Centres are being set up in China, India, Brazil and the US. They are all based in forests that are affected by human activities in ways that are typical of the regional conditions.

For instance, the Indian site in the Western Ghats, which opens this February, is heavily affected by a large human population using the woodlands for their livelihoods. The Atlantic forest in Brazil has suffered massive losses in large-scale clearing, while the US site in the District of Columbia is reverting to woodland after a period of agricultural use. The main feature of woodlands in Britain is fragmentation: many wooded areas are so small that they mainly consist of edge, and there is virtually no 'deep forest'. Wytham is relatively unusual in providing this as a contrast to the edge and fragments in the surrounding area.

In all five centres, scientists and volunteers recruited from the regional HSBC operations will explore how human activities relating to the forests affect their function in the carbon cycle and as a habitat for wildlife. 'A lot of recent work has been done in pristine forests,' Bebber says, 'but it is not known how human impact on the forests affects the carbon balance.' He hopes that the HSBC Climate Partnership, initially funded for five years, will contribute valuable scientific data on how forests respond to climate change, and what kind of forest management is required to help mitigate this change and adapt to its consequences.

Mike Morecroft, an ecologist with the Centre for Ecology and Hydrology (CEH) at Wallingford and a senior research associate at the University's School of Geography and the Environment, is involved with the tree studies at Wytham. 'The key questions are,' he says, 'where does the CO2 go? How much goes into the leaves, into the stems and into the roots? And for how long is it removed from the atmosphere?' The answers cannot be predicted by current models. Subtle changes in the relative speed of vegetation growth and the decomposition of plant material on the forest floor may lead to either a net removal or a net emission of CO2. Depending on how these unknown quantities change with the changing climate, forests may make things either better, or worse.

This is why the volunteers measure the tree trunks regularly and why they collect and categorise the fallen leaves. Monitoring the root growth is somewhat more difficult and is left to the experts, as is the more technical work in the forest canopy involving cherry-pickers (mobile elevated platforms). Within the limits of what volunteers can be trained to do in a short time, however, Morecroft says he is 'pleasantly surprised' by the quality of the work that they have delivered. All checks have shown that the results are consistent between different teams and can be reproduced by the professional scientists involved, including postdoctoral researcher Terhi Riutta, who is the principal investigatoron the trees project and works with Professor Yadvinder Malhi at the Environmental Change Institute.

Using large numbers of volunteers in conservation research is a relatively new approach pioneered by Earthwatch. The most obvious advantage is that it makes available large amounts of manpower that would otherwise not be affordable. At Wytham Woods, the volunteer teams will deliver a grand total of 40,000 hours of fieldwork, the equivalent of a single person working for 21 years.

The other important aspect of volunteer work is that the lay people who participate in the research projects learn a lot about the issues that are at stake, such as conservation and climate change, and can on their return to their everyday activities help to spread the general knowledge of these issues. This aspect has been of particular interest to HSBC, where the learning experience that staff members go through during the projects is valued, and they are encouraged to share their experience as 'climate champions' after their return.

Su Henton, a business marketing manager based at Canary Wharf, London, was a member of the second team of HSBC climate champions, and spent two weeks at Wytham Woods in May. Since her return, she has given a presentation to some of her colleagues explaining what the HSBC Climate Partnership is and how she became involved in it. She talked about what she and her 11 team-mates had achieved during their two weeks working alongside Earthwatch scientists. She also spoke about the work she has been doing to address sustainability issues within the business.

Another thing that Henton has done since her return is preside over a Carbon Footprint Challenge. She is involving her colleagues in calculating their current departmental carbon footprint, and is looking at ways in which it can be reduced. She is also heading up a 'Green Team' of HSBC employees who are keen to get involved in the Climate Partnership, but who are not yet ready to go out to the woods. The team is investigating a number of ways of improving their department's eco-credentials. One of the first initiatives is to look into the sustainability policies of their suppliers - printers, design agencies, etc. - and identify where there is room for improvement.

Similarly, the researchers and the people in charge of the actual woodlands in question will hope to learn how forest management can become greener. For instance, Dan Bebber explains: 'There is a lot of discussion about what to do with the dead wood on the forest floor. Is it better to leave it to rot and benefit biodiversity, or should it be collected to be turned into biofuel?' Only a detailed understanding of the carbon economy of forests can enable researchers to answer such questions.

Morecroft points out a similar dilemma. When creating additional woodland in the UK, should the aim be to increase the sizes of existing patches, or favour a looser, wider network of interconnected small wooded areas? At the moment, it appears that the trees would benefit from larger forest size, as the edges of forests are more vulnerable to droughts. Certain animals, however, might benefit more from a network of small areas, as they could more easily move in response to climate change.

At the moment, the overwhelming impression is that we know far too little about what's really going on in the woods, and we don't know what would be the greenest way to manage the unavoidable impact of human activities on our forests and their inhabitants. But thanks to the groundbreaking collaboration between the University, Earthwatch, HSBC and other institutions, and the enthusiastic help of their volunteers, we may have a much better understanding in about five years' time.