Distribution of coarse and fine root biomass in native ecosystems and planted pasture in the Cerrado of Central Brazil
Patricia
Rodin, UnB, prodin@unb.br
(Presenting)
Carlos
Augusto
Klink, UnB, klink@unb.br
Flavia
Pinto, INPA e PDBFF, flavia@inpa.gov.br
Thiago
Andre, INPA, thiago@inpa.gov.br
The depth and distribution of roots have important implications for ecosystems, as they define the input of carbon into the soil by senescent roots. Our objective was to estimate the coarse and fine root (< 2mm diameter) distribution in three native Cerrado ecosystems and one planted pasture in Brasilia. We dug 3 deep shafts (up to 8 m deep) in each ecosystem to determine coarse root distribution. The soil was collected at 0-10, 10-50, 50-100 cm intervals and then at 1m intervals. Fine roots were sampled with an auger up to 3m depth (N = 10 per ecosystem). The soil was collected at 10 cm intervals up to 50 cm depth and then at 50cm intervals. Roots were washed and oven dried at 70oC for 72 hours and weighed. We fitted the depth coefficient â to the data of coarse and fine root biomass of each ecosystem. â is a numeric index of rooting distribution based on an asymptotic equation Y=1-âd, where Y = the cumulative root fraction from the soil surface to depth d (cm). In all ecosystems root biomass declined sharply with depth. All ecosystems showed deeper rooting profiles, for coarse and fine root, and a positive increase of coefficient â with density of woody vegetation. â for coarse root biomass varied between 0.970 in pasture to 0.985 in cerrado stricto sensu; for fine roots, â varied between 0.964 in pasture to 0.985 in cerrado denso. Conversion of native ecosystems into pasture affects distribution of root biomass, which may affect net carbon storage in the soil, and carbon recycling in the Cerrado.
Submetido por Patricia Rodin em 10-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)