Design Difficulties in Stand Density Studies

Abstract

Designing unbiased stand density studies is difficult. An acceptable sample requires stratification of the plots of age, site, and density. When basal area, percent stocking, or Reineke's stand density index is used as the density measure, this stratification forces a high negative correlation between site and number of trees per acre. Mortality in trees per acre is correlated with real density (basal area, percent stocking). As a result, in a controlled study, mortality in trees per acre is about the same on aU sites. This, in turn, means mortality in cubic volume is strongly and positively correlated with site. The measured effect of site on growth is greatly reduced. When dealing with merchantable volumes, ingrowth is negatively correlated with site, and this also reduces the measured effect of site on growth. Although these problems cannot be eliminated, this paper offers suggestions for reducing their effect.

Citation

Bennett, Frank A. 1969. Design Difficulties in Stand Density Studies. Res. Note SE-111. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 5 p.