Changes projected in the climate will affect tree growth in most parts of the world. Warmer and wetter conditions in many temperate regions, at certain times of the year, will favour many trees. But if the trees grow faster will this be good for sequestering carbon and for producing more home-grown timber?
For conifers that produce softwood timber, their accelerated growth will lead to a fall in timber density and therefore strength. As a large part of the market for softwood is the construction industry then the consequences may be quite serious.
Broadleaved trees producing hardwood timber on the other hand are likely to be affected positively by a warming climate, as a longer growing season will lead to increased yields without loss of strength. Why?
Broadleaved trees can be split into two types in terms of their hardwood timber character.
1. Diffuse-porous wood type: timber quality is independent of growth rate. Species include beech, birch, wild cherry, maple and sycamore.
2. Ring-porous wood type: these act the opposite of softwoods, becoming denser, harder and stronger with increased growth rate. Species include ash, oak, sweet chestnut and walnut.
So what does this mean for carbon management in our woodlands? Simply, the better the quality of timber produced the greater the carbon sequestration; as the carbon is locked into solid wood products for longer. The long rotation time (time between planting, felling and restocking) and the high long-term yields are also factors in favour of hardwood forestry for carbon sequestration.
Riutta, T., Malhi, Y., Morecroft , M. and Savill, P. (2011). Temperate, broadleaved forests as carbon sinks; implications for forest
policy in the UK. To be made available later in March on the BIHIP website.