Dinámica hidrogeomorfológica y pérdidas de suelo en laderas sometidas a distintos manejos forestales

Resumo

The purpose o f this study is to evaluate the effect of 3 post harvesting management systemsusually used in a mountains region of Northern Spain on hidrogeomorphologic dynamic. The techniques evaluated were a) conventional stem-only only harvesting (T), b) whole tree harvestingand humus layer removal (TE) and c) whole tree harvesting and humus layer removal followed by down-slope deep ploughing (TES). Soil erosion and hidrogeomorphologic characteristics were measured in 58 recently clearfelled radiata pine plantations over the period between the stand harvesting and establishment o f understorey vegetation. They were located on slopes with gradients of between 40-50%. For every treatment the associated runoff-rainfall ratios were high, indicating inherent low permeability of the soil. Intense site preparation (TES) resulted inconsiderable decreases in soil organic matter and increases in bulk density, which decreased the hydraulic conductivity and subsequently produced higher run-off. The results indicate that, inorder to maintain the soil productivity and for conservation purposes, harvesting management should minimise the soil disturbances and maintain the slash and vegetative cover.