Natural regeneration of pine plantations in South Africa as a cost-effective way of stand re-establishment.

摘要

For about 100 years, South African forestry developed a paradigm of highly intensive and expensive silvicultural technology practiced predominantly by large corporations. A broad scientific perspective on diverse silvicultural options for a wide variety of users has received little attention. As costs of intensive silviculture grow with increasing costs of energy, machinery and chemicals, large plantation areas are likely to be deforested with detrimental impacts on jobs, existing infrastructure and rural economy. This study shows an example of how timber production and profitability of pine plantations can be improved with the use of cheaper natural stand regeneration. Large-scale compartment data from the Cape plantations showed a significant trend for improved timber yields in naturally regenerated stands of Pinus radiata D. Don but not in P. pinaster Aiton. The Equivalent Annual Income (EAI) for P. radiata was improved on a hectare basis by up to US$14.8 due to (1) a saving of up to US$208.6 on tree establishment and (2) higher timber volume in naturally regenerated stands. The EAI is improved even where timber yields are significantly less, as is the case with P. pinaster, because of lower establishment costs. Assuming that natural regeneration can be successfully implemented in other parts of the country, the extrapolation of these results to two-thirds of the total area under pines, produced an impressive prospective saving of US$5 million per year or additional profit of over US$11.2 million based on a modest 4 per cent real interest rate and a 22-year average rotation cycle. Therefore, the unqualified exclusion of natural regeneration of pines may be a serious economic and social mistake made by large and small timber growers alike to the detriment of forestry-based rural development in South Africa.