Optimal management of the Umbundu traditional land use system in the central Highlands of Angola

Abstract

The study reviews one publication on the traditional land use system in Angolan highlands, three publications on modelling the growth and yield of nine tropical pine and six eucalypt species, and one publication on optimising the land use in Angolan highlands. The sources of data for the land use system analysis were two years field research and a review of previous studies going back to colonial times. The growth models were based on 19,388 radial increments from 1,059 measured pine trees and 10,499 radial increment observations measured on cores taken from 803 eucalypts trees. Linear programming (LP) was used to optimize the combination of alternative production systems. LP problems were formulated and solved for a baseline land use, improved diet, and maximal timber production land uses. The first study has implications for land use management (e.g. regarding length of fallow) and conflict management in Angola and elsewhere. The developed growth and yield model set included dominant height, diameter increment, tree height and self-thinning models for all the studies pine and eucalypt species. The model set makes it possible to simulate stand development on an individual tree basis. They showed good accuracy when the simulated stand development was compared to the observed development. Therefore, they can be used as a management planning tool in tropical pine and eucalypt plantations in Angola. The developed models were used in the last study to calculate the timber production in shortand long-rotation forestry. The last study showed that among the alternative production systems, cash crops under forest fallow showed the highest land expectation value (LEV). Changing diet by diversifying carbohydrate and protein sources increased LEV and reduced the seasonal need for women labour. In the maximal timber production alternative under food sufficiency constraint the optimal share of tree plantations was around 57% of the total land area.