Ecological and mathematical considerations on self-thinning in even-aged pure stands

Abstract

A new model is proposed to unite the logistic theory of plant growth and the 3/2 power law of self-thinning, which so far have been applied independently to growth analysis. To construct the model the following assumptions are made: a general logistic curve of mean plant weight, a modified form of the formula to show the rule of constancy of the final yield, which is generalized to cover the conditions of different combinantions of density and linear factor supply in a nonself-thinning population and a special population with a specific initial density which follows thew-ρ trajectory of the 3/2 power law type and has an exponential decrease in its density with biological time. Model calculations show that the Sukatschew effect is successfully formulated, that there should be a minimum factor supply below which self-thinning does not occur and that thew-ρ trajectory should be segregated acoording to the level of the linear factor supply.