Aboveground Biomass Partitioning Due To Thinning in Naturally Regenerated Evenaged Shortleaf Pine (Pinus Echinata Mill.) Stands in Southeast Oklahoma

Abstract

The effects of thinning on tree biomass components of approximately 40-50 year-old shortleaf pine (Pinus echinata Mills.) stands on two sites in southeast Oklahoma were analyzed. These naturally regenerated stands were thinned during 1989-1990. Thinning treatments included unthinned control plots and plots thinned to 70%, 50%, and 30% of full stocking. Total tree and bole wood biomass in thinned plots were found to be converging towards their unthinned counterparts. For example, the thinning to 70% of full stocking treatment has already exceeded the biomass contained in its unthinned counterpart on site one in 16 years. However, heavily thinned stands may take much longer to converge. Foliage and bark biomass reduced with an increase of thinning intensity. The proportion of biomass partitioned to branches and bark was significantly affected by thinning. Unless heavily thinned, thinning treatments did not significantly affect the proportion of biomass allocation to bole. Although thinning seemed to reduce the total foliage biomass, it seemed that heavily thinned stands increase in terms of proportion of foliage to total biomass; however it was not statistically significant. Better site quality was associated with allocation of more biomass to bole wood and less to foliage.