A review of site-growth studies in South Africa

Abstract

The intensive nature of the South African forest industry requires reliable decision support systems to enhance site-specific silviculture. Furthermore, the principle of ecologically sustainable forest management requires a profound improvement in the understanding of the factors controlling tree growth and the limitations of the sites on which they are planted. The lack of quantitative evaluation systems for accurate site-species matching necessitated South African forest researchers to develop site-growth models to initiate the development of plantation decision support systems. The objectives, principles and procedures for developing site-growth models are discussed, together with the main advantages and disadvantages of implementing such models on operational forest management levels. Recommendations for a future strategy in site-growth studies are provided. The simulation of ecological processes influencing tree growth will, in future, receive preference over the use of discrete site variables to predict the growth of trees.

Die intensiewe aard van die Suid-Afrikaanse bosbou-industrie vereis betroubare besluitnemings-ondersteuningstelsels om presisie boskultuur te bespoedig. Die beginsel van ekologiese volhoubare bosbestuur vereis verder 'n beter begrip van die faktore wat boomgroei beheer en die beperkings van die groeiplekke waar plantasies gevestig word. Die tekort aan beskikbare kwantitatiewe evaluasie stelsels vir die akkurate toewysing van spesies aan groeiplekke, het Suid-Afrikaanse bosbou navors-ers genoodsaak om 'n benadering van groeiplek-groeimodellering te volg. Dit kan die ontwikkeling van meer holistiese plantasie-besluitnemingstelsels inisieer. Die doelwitte, beginsels en prosedure vir die ontwikkeling van groeiplek-groeimodelle word bespreek, tesame met die hoof voordele en nadele van die implimentering van sodanige modelle op operasionele bosbestuur vlakke. Aanbev-elings vir toekomstige strategiese studies van die aard word verskaf. Die simulering van ekologiese prosesse wat boomgroei bernvloed sal in die toekoms voorkeur geniet bo die gebruik van diskrete groeiplek veranderlikes vir die voorspelling van boomgroei.

Key words:

• site classification
• site-growth models
• sustainability
• decision support systems
• Pinus spp.
• Eucalyptus spp.

Sleutelwordes:

• groeiplek-klassifikasie
• groeiplek-groeimodelle
• volhoubaarheid
• besluitneming-ondersteuningstelsels
• Pinus spp.
• Eucalyptus spp.