Soil organic matter dynamics and physico-chemical properties of intensively-managed Eucalyptus plantations compared to native forests in the Brazilian Amazon
Troy
Patrick
Beldini, NASA-LBA ECO project, Santarém, Brazil, beldini@lbaeco.com.br
(Presenting)
Kenneth
L.
McNabb, ,
B.
Graeme
Lockaby, ,
Felipe
G.
Sanchez, ,
Eucalyptus species have been promoted as an industrial plantation tree due to superior growth rates, biomass yield and pulp quality. Increasing forest management intensity has been forwarded as a strategy to slow deforestation in the Brazilian Amazon. However, the effects of intensive management and multiple rotations on soil structure and function are poorly understood. Assuming that long-term site productivity is controlled by soil organic matter maintenance, this research investigated soil organic matter dynamics as an indicator of sustainability.
The carbon cycling dynamics of Eucalyptus plantation soils were compared to identical, adjacent undisturbed primary forest soils on the Jarí Plantation in the Brazilian Amazon.
Forest types were compared on clay and sandy soils. Total soil carbon stocks to one-meter depth on each soil type were equal in native and plantation forests, indicating that successive rotations of Eucalyptus have not depleted carbon stocks. No differences in soil bulk density across one meter were found during several measurement seasons. Physical soil fractionation results have quantified a shift in carbon from labile soil particle-size fractions to less labile fractions in the plantation on the sandy soil, indicating a possible decline in soil quality. Litterfall and root biomass in each plantation were significantly lower than in the adjacent native forests, and air and soil temperatures were significantly greater in each plantation. These results indicate a reduction in carbon inputs into the plantation soils and a potential for increased rates of soil carbon decomposition processes due to a more extreme air and soil temperature regime.
Submetido por Lorena Cordeiro Brewster em 17-MAI-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)