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Jaru Biological Reserve, Rondonia Brazil
Spatial Variation of Forest Structure and Aboveground Biomass
in the Southwestern Brazilian Amazon
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Spatial variation in tropical rain forest structure is an important factor in quantifying the aboveground biomass (AGB) and carbon stock and extrapolating plot measurements to regional or global scales. We collected forest structural data in five 5 hectare plots in the intact lowland forest around the flux tower at the Jaru Reserve in Rondonia, Brazil. The data were analyzed to address the spatial variability in stem density, basal area, canopy roughness, and the aboveground live biomass (AGLB). The plots were transects 1 km long and 50 meter wide and were designed prior to the field survey with the help of a one meter resolution IKONOS imagery over spectrally homogeneous regions away from disturbances. Five 50 m x 1000 m nested transects were installed and Live trees with diameter at breast height (DBH) ≥ 35 cm were collected within the 50 m wide transect with an addition of trees ≥ 5 cm in the narrower transect (5 m x 1000 m) in the middle of wider transect. Among the total of 3626 trees measured on all transects, trees with DBH ≥ 5 cm had average frequencies of 1015 ha-1, whereas the trees ≥ 35 cm had a frequency of 48 ha-1. Allomertic equations based on DBH were used to compute canopy height and above ground biomass for various segments of the transect to estimate the effect of spatial scales from 100 m to 1 km on forest structure and biomass estimation.
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