Forty years of silvicultural management in southern Nothofagus pumilio primary forests

To achieve sustainability of a forest system it is necessary to apply appropriate silvicultural management, including preservation measures. The characterization of the status and development of the harvested stands, as well as the timber potential of the unmanaged ones, is necessary to achieve a sustainable forest management. In southern Patagonia, Nothofagus forests are the basis for the sawmill industry. Since European colonization, different silvicultural management regimes have been applied in primary forests. Forestry policies and available sawmill technologies have also been involved. There is little knowledge about the consequences of the different silvicultural systems implemented, as well as about the regeneration status of the harvested stands and future possibilities of the managed forests. The objective of this work is to analyse the logged, affected from harvesting and current forest structures, as well as the regeneration development during the last 40 years and the consequences derived to forests of southern Patagonia. The harvesting was applied irregularly between the studied decades (30 (plus-minus) 15% of the original basal area was removed) creating an irregular forest structure. Large quantities of sawn logs were abandoned in the forest floor and a high percentage of the remaining forest structure was damaged during the harvesting. Negligent management and wind throw produced a huge amount of wasted timber, resulting in a scarce standing log volume of very low quality. Nevertheless, regeneration was successfully installed (222 (plus-minus) 185 thousands/ha) within the harvested stands. No differences in the harvesting intensity were found with the different theoretical silvicultural methods applied through the years (selective cuts, clear-cuts or shelterwood cuts). As a result, the forests present a low current and future economical potential. Hence, the status of the secondary forest must be improved and regulated in order to achieve sustainability. Otherwise, the local forest industry will suffer from negative consequences, and this valuable resource will not be profitable in the future.