ESTIMATING THE SELF-THINNING BOUNDARY LINE AS A DENSITY-DEPENDENT STOCHASTIC BIOMASS FRONTIER

Abstract

The self-thinning rule describes a density-dependent upper boundary of stand biomass for even-aged pure plant stands in a given environment. The econometric approach of stochastic frontier production functions is adopted to estimate the self-thinning boundary line as a density-dependent stochastic biomass frontier using data from even-aged Pinus radiata stands. This method uses all the data points, but recognizes the differences in site occupancy among them. Since no subjective data selection is involved and no information contained in the data is lost, the line can be estimated without subjectivity and more efficiently than the common methods of subjective data selection. As a result, statistical inferences about the estimated self-thinning boundary line can be made objectively and more precisely. In addition, the estimates of site occupancy provide further insight into the dynamics of self-thinning stands.