Acceso usuarios
J. P. Carvalho
A mechanical technique for forest vegetation treatment is presented and analysed. A brush-cutting machine was used with Mediterranean-type vegetation in a forest vegetation management program to enhance wildlife habitat by promoting vegetation resprouting and grass reestablishment in mature shrublands. The performance of working time components was evaluated. Equipment components are described as well as benefits and applications of the technique. Two sites were compared in terms of vegetation composition and biomass, mechanical working performance, and litter decomposition rates. Litter decomposition was followed over a 2-year period. Changes in litter mass and nutrient content through time are evaluated and discussed. A working productivity between 3 and 4 h.ha-1 was obtained for different site and vegetation conditions. A major reduction of litter dry mass happens in the first 6 month after vegetation cutting. Litter decomposition rates range from -0.32 to -0.14 year-1 and the time for total decomposition ranges between 4 to 6 years. Litter nutrient composition presents the following order N>Ca>K>Mg>P. The relative mobility of these nutrients follows the order N>K>Ca>Mg>P. The estimated annual nutrient net release is about 91.8 kg N.ha-1, 4.5 kg P.ha-1, 52.8 kg K.ha-1, 39.5 kg Ca.ha-1 and 13.7 kg Mg.ha-1.
Different litter decomposition rates and nutrient release on both sites and are discussed.
