Advances in modelling and decision support systems for vegetation management in young forest plantations

The two most common forest vegetation management objectivesare to (1) minimize resource competition, and (2) to developmethods for managing specific weed species. This paper reviewsrelevant models and decision support systems for assisting inachieving these objectives. The aim of reducing resource competitionis to increase crop-tree growth and survival. Several modellingapproaches have been applied to this problem and these generallyestimate crop survival and growth benefits following some formof generalized weed control. Linkages with models of older treecrops are needed for comparing vegetation management strategiesin the context of complete silvicultural regimes. More refinedindividual tree models use competition indices to estimate thequantity of weed vegetation within the growing space aroundeach tree. The indices reflect resource use by the weeds andare sensitive to changes in weed growth over time and to theapplication of specific vegetation management treatments. Hybridand process-based models have the potential to provide moregeneralized models of inter-specific competition, but theirusefulness for forest practitioners has yet to be proven. Someforest vegetation management problems require a more detailedunderstanding of the biology and ecology of a specific species.In this case, different modelling approaches that consider overallweed population dynamics, distribution or spread may be appropriate.