Mitigation of biodiversity loss in Nothofagus pumilio managed forests of south Patagonia.

LENCINAS MV; MARTÍNEZ PASTUR G; GALLO E; MORETTO, A; BUSSO C; PERI, P

Bariloche, 26-30 Junio

Workshop; Workshop on Forest Fragmentation in South America.; 2006

CEMAGREF - UNCOMA

Since their beginnings, forest management in South Patagonia was mainly based on economical and forest structure variables. To develop new silvicultural systems it is necessary to know the impact of these traditional methods over biotic and abiotic components, as well as biodiversity of the original ecosystem. A project with three stages was done. First two stages evaluate diversity changes due to forest management (understory plants, birds, insects and Lama guanicoe), and diversity in timber and non-timber forest environments. Forest management modifies birds communities, but they reach the original values when the cycle ended; understory plants have similar changes, but allow to alien species establishment; Lama guanicoe populations change according to forest structure; and insect diversity abruptly diminish along the cycle. On the other hand, understory plants and birds (except big predators as Accipiter bicolor) are well represented in non-timber forests, while most of the insect species are only found in timber stands. Due to the adverse results in biodiversity loss, mainly over insect communities, the feasibility of new silvicultural system was analyzed. The last stage of the project evaluates a new regeneration system based on dispersed and aggregated retention. This system maintained 80% of the insect diversity during the first years after the harvesting, and most of the studied abiotic factors inside the aggregates (microclimatic variables, soil properties, nutrient cycles, mineralization and decomposition). Actually, this new silvicultural system was the mainly applied on the private forests in the argentine sector of Tierra del Fuego.