Management options

 

Forests and woodlands can be managed to mitigate greenhouse gas emissions, and a variety of approaches can be taken to adopting 'carbon conscious' management. For any particular woodland the choice between carbon management options will depend on many ecological and economic factors, such as the biodiversity value of the woodland, the levels of carbon already present in the soil and the suitability of the site for access to harvest timber. It is unlikely that any single woodland will ever be managed to achieve the 'optimal' carbon balance, because this is just one of many benefits we aim to deliver through woodland management. In each woodland the balance between carbon management and (for example) management for recreation, conservation and timber production will be different, so there is no 'one size fits all' solution. Despite this, three broad options for forest carbon management can be recognised:

Carbon reserve management

This option is characterised by minimal intervention, with a gradual long-term increase in carbon stocks. In addition to a climate change mitigation role, carbon reserve management may also have significant amenity and biodiversity benefits, particularly if native species are planted. Loss of carbon through fire, drought, floods or storm damage is minimised. For this reason it is necessary to take account of wind-hazard, flood risk and climate change predictions regarding the suitability of a particular site-species combination to achieve this objective. At the same time, the use of fossil fuel during woodland management operations should be minimised so as not to negate any enhancement of carbon stocks. Carbon reserve management is particularly well suited to forest stands with very low growth rates and poor stem quality, or in localities where there are limited opportunities for use of harvested wood. The most extreme example of carbon reserve management might involve conservation of existing forest carbon stocks through avoidance of deforestation.

Carbon substitution management

This is characterised by cyclical changes in carbon density in the forest ecosystem, with maintenance of on-site carbon stocks being of secondary importance. This form of carbon management and its objectives are not far removed from the production forestry practised across most of the UK. Woody biomass is harvested as good quality stemwood for use in product displacement and renewable woodfuel (in the case of thinnings and harvest residues). Soil disturbance following thinning or clearfell is minimised to limit carbon emissions. Because of the high nutrient content of a significant proportion of branchwood compared with timber, often only a carefully selected fraction of this material is harvested, primarily avoiding the removal of foliage. As with carbon reserve management, there may be benefits associated with the woodland in addition to its climate change mitigation role. Carbon substitution (or displacement) management is particularly well suited to even-aged forest stands with moderate to high growth rates in localities with obvious opportunities for use of harvested wood. Short rotation coppice managed for bioenergy production represents the ultimate expression of carbon substitution management. Stem quality may also require consideration when options are being evaluated, because it will have an impact on the potential to convert stemwood into different products.

Selective intervention carbon management

This option is similar to carbon reserve management but, in addition, there is low-level harvesting of certain trees to clearly defined specifications in order to supply high-value niche applications. It is well suited to stands containing trees of variable quality where risk of significant natural disturbance is low and which may be some distance from centres of population or industry. Examples of this type of management include occasional tree harvests in stands to meet a requirement for fuelwood in a small local community and selective felling in continuous cover forestry systems to satisfy specialist timber markets.