The effects of forest harvesting in the first stages of lenga leaf litter decomposition in Tierradel Fuego, Argentina

MANSILLA, ROMINA; PANCOTTO, VERÓNICA; MORETTO, ALICIA; VRSALOVIC, JAZMÍN; LENCINAS, VANESSA

Bariloche

Congreso; IV Souther Connection Congress; 2010

Nothofagus pumilio (lenga) forests of Tierra del Fuego are mainly managed by shelter-wood cut, but changes of its impacts on decomposition process remain unknown. Our objective is to evaluate lenga litter decomposition in forests of Tierra del Fuego, managed by shelter-wood cut, considering the main associated situations and recovery with time. We focus on three situations: 1) shelter-wood cut area, 2) stockpiled area, and 3) undisturbed forest (control); through the whole cycle management: at 1, 5-10, and 50 years after harvesting (YAH). We evaluated decomposition of organic matter using litter bag method. At three month of decomposition, mass loss was higher (F=11.2, P<0.05) in impacted sites (shelter-wood cut and stockpiled areas) (17%) comparing with control (14.5%). The time since harvesting did not show differences in mass loss (F=1.23, P<0.29), however phosphorous and potassium release were higher (F=8.5 and F=10.4 respectively, P<0.01) for recently harvested forests (1 and 5-10 YAH) than for the older sites (50 YAH). These preliminary results suggest that decomposition process in Tierra del Fuego lenga forests is affected by harvesting, and the recovery to preliminary conditions take more than 50 years.