Stand Density Management: Results from Research in Southern Pine

Introduction The relationship between stand density and volume growth in southern pine species is a topic of long standing interest. Early work includes that of McClay (1955) who studied the relationship between periodic annual growth per acre and residual stand density after thinning measured as basal area. Using linear regression analysis he found a trend of increasing growth with increasing residual stand density up to a point where growth is maximized. Whether the growth levels decline beyond this point could not be determined conclusively because of a lack of data from high density stands. Similar regression analysis was performed by Wenger et al. (1958) to study the effect of growing-space requirements for thinned and unthinned natural stands of loblolly pine for a 5-year period. In thinned stands the relationship between volume growth and density varied with site quality, but not with stand age. Alternatively, both variables were significant for unthinned stands.