Sources: UK Forests and Climate Change
Forests can help address climate change by reducing the amount of greenhouse gases in the atmosphere. They do this by absorbing carbon dioxide, using the carbon to produce sugars for tree growth and releasing the oxygen back into the air. As trees grow, they store carbon in their leaves, twigs and trunk, and in the soil around them.
Globally, deforestation caused by the unsustainable harvesting of timber and the conversion of forests to other land uses accounts for almost 20 per cent of global carbon dioxide emissions. The amount of carbon stored can be increased by actions to reduce the amount of deforestation and to convert non-forested areas to forest.
Although they cover a small part of the global area, the forests and woodlands in Britain have a role to play too. They can be managed as a sustainable source of wood – an alternative energy source to fossil fuels, and a low-energy construction material.
Woodlands can also help society adapt to a changing climate. The right trees planted in the right places can reduce the risk of flooding, provide shade for wildlife, reduce soil erosion and help to cool down towns and cities.
The diagram showing the carbon cycle is adapted from Figure 3 of the Forestry Commission Information Note on Forests, Carbon and Climate Change: the UK Contribution (M Broadmeadow and R Matthews, 2003).
Forest carbon stock
Table 4.1 is a slightly reduced version of Table T8 in the final draft UK report for Global Forest Resources Assessment 2010. Sources and methodology are described in more detail in that report.
Figures for growing stock were from models based on the 1995-99 National Inventory of Woodland and Trees and data for the FC estate, converted to estimates of above-ground and below-ground biomass using standard factors, then converted to carbon assuming 50% carbon in biomass.
Figures for deadwood were based on the 1995-99 National Inventory of Woodland and Trees. Figures for litter were based on data from the Centre for Ecology & Hydrology (CEH). Figures for soil carbon were based on data from CEH, adjusted to take account of the changing forest area.
The information in Table 4.2 is taken from inventory and projections of UK emissions by sources and removal by sinks due to land use, land use change and forestry (CEH, 2009). They exclude the pool of carbon in timber products.
Figure 4.2 shows annual estimates of carbon sequestration by country, taken from the same source but shows carbon in living forest biomass only; it excludes carbon in litter, soils and forest products. Future predictions of carbon uptake assume that commercial conifer plantations will be replanted when felled, and that planting of new woodland will continue at the same rate as in 2007 (mid projection).
Emissions and sequestration can be presented as tonnes carbon or tonnes carbon dioxide (CO2). To convert from tonnes CO2 to tonnes carbon multiply by 12/44.