Soil biochemical characteristics under second growth forests of distinct ages and former land use in central Amazonia
Fabiane
Lima de
Oliveira, INPA, fabiane@inpa.gov.br
(Presenting)
Regina
C.C.
Luizão, INPA, rccl@inpa.gov.br
Flavio
J.
Luizão, INPA, fluizao@inpa.gov.br
In central Amazon, soil preparation for pastures and croplands in upland forest soils involves biomass burning after deforestation, which adds ashes to the soil, changing its nutrient status, organic matter content, and physical properties. These practices affect both crop yields and the subsequent secondary vegetation after land abandonment. This study aims to evaluate the quality of the litter layer produced by second growth of different ages and origins, and to determine its relationship with soil nutrient availability. The study is carried out at the Biological Dynamics of Forest Fragments Project (BDFFP), 80 km north of Manaus, using 20 second growth transects for sampling the litter layer and the upper soil layer (0-10 cm). No direct relationship between soil properties and the litter layer mass or quality were detected in the first sampling. However, the litter layer mass varied significantly with the age of second growth (p<0.001), and with the kind of former land use (p<0.001). Soil pH (3.42-4.79) did not vary significantly with the age of second growth, but it was greater in second growth installed on abandoned pastures. Soil moisture (11.1-30.5 %) and field capacity (22.6-52.5 %) did not show significant differences among ages or among distinct previous land uses. The decrease of the litter layer mass with the age of second growth is likely a result of a more efficient decomposition process in older second growth, which may produce litter of better quality.
Submetido por Fabiane Lima de Oliveira em 25-MAR-2004
Tema Científico do LBA: LC (Mudanças dos Usos da Terra e da Vegetação)