The carbon consequences of thinning techniques: Stand structure makes a difference

Using results from a 25-year study of thinning in a northwestern Pennsylvania Allegheny hardwood stand, we assess whether and how thinning method affected carbon sequestration and merchantable volume production. Plots were thinned to similar residual relative density by removing trees from different portions of the diameter distribution. Plots that were thinned from below had greater volume production and carbon sequestration rates than plots that were thinned from the middle or thinned from above. Control plots, which were not thinned, also had higher carbon sequestration rates than plots thinned from the middle and higher merchantable volume production and carbon sequestration rates than plots thinned from above. In this forest type, changing stand structure by thinning can affect carbon sequestration and stand growth either positively or negatively. Those effects can be significant, with long-term implications for the growth of the stand. In general, structures that favored volume production also favor carbon sequestration.