A FALLACY IN THE THEORY OF GROWING STOCK

Abstract

It is generally accepted that the theories of growing stock of von Mantel, Oettelt, and Pressler which in themselves are not strictly applicable to yield management of even-aged normal forest are equally applicable to uneven-aged selection forest and irregular forestry. Attention is drawn to the marked differences demonstrated in Switzerland between selection and uniform growing stocks. Figures for British beechwoods are given which also demonstrate this difference. It is fallacious therefore to apply methods of yield regulation for uniform forests to selection or irregular areas. There is a far greater volume of timber per acre in normal selection forest than in normal uniform forest. The physiological reasons are outlined and the evolution of irregular silviculture from unsatisfactory uniform methods on the Continent is discussed. Mixed woods of several species in harmony with local ecology are considered most suitable components of irregular stands, sharing air, light, and soil more efficiently and providing more suitable regeneration conditions. Figures from successive enumerations in Chiltern beechwoods are given to show development from uniform to irregular stocking, and the economic as well as volumetric advantages are demonstrated.