An unconventional approach to timber yield regulation for multi-aged, multispecies forests. II. Application to a South African forest

Abstract

The development and implementation of the senility criteria yield regulation system to the multi-aged, multispecies forests of the southern Cape, South Africa, is described. The described yield regulation system aims to maximise the sustainable yield with minimised artificial impact on the ecology and minimised managerial input. The felling cycle is 10 years, which is still considered compatible with the prevailing natural disturbance regime. Harvestable trees are not defined by minimum harvestable diameters, but according to signs of senility or reduced remaining life expectancy (e.g. percentage crown dieback or base rot). These criteria are determined for canopy species in accordance with species-proportional turnover rates. The gross increment of the stand is thus realised as harvest through periodic mortality preemption by harvesting those trees which have reached a defined level of senility or reduced life expectancy. Advantageous characteristics of the senility criteria yield regulation system relate to guaranteed sustainability, compatibility with nature conservation aims, optimal productivity and managerial simplicity and flexibility. The potential of the system for wider application is discussed.