Índices de vegetação e valores de proporção na caracterização de floresta tropical primária e estádios sucessionais na área de influência da Floresta Nacional do Tapajós-Estado do Pará / Vegetation indices and fraction values to characterize primary rainforest and sucessional stages in the area of influence of Tapajos National forest - Para State

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

In May 1995, a field campaign was carried out in the innerside and proximities of Tapajós National Forest - Pará State, aiming to measure dendrometric variables and leaf area index (LAI) in vegetation communities of tropical rainforest and regrowth, represented by three stages, c1assified in function of age: less than 5 years; 5 to 10 years and more than 10 years. The vegetation communities were described according to the parameters: floristic composition, density, basal area, biomass (estimated by alometric equations) and LAI. The study, involving Remote Sensing techniques used a times series of rectified imagery from Landsat-TM 5 satellite, refered to the years of 1984, 1986 to 1989, 1991, 1992 and 1995. The image processing involved the calculation of digital values of vegetation indices (NDVI and SAVI) and fractions of vegetation (PVEG), soil (PSOL) and shade (PSOM), generated by a mixing model analysis. The digital data analysis was implemented by means of two approaches. The first one utilized samples of the digital values taken from the time series and analysing the evolution of the secondary sucession process. It was observed that the calculated NDVI values didn t allow to distinguish the sucessional stages, excepting "younger". The SA VI and PVEG values showed similar behaviors and reduction was verified in PSOM detriment, as sucessional process evolves. The second approach involved the jointed analysis of biophysical parameters and digital values, taken from representative segments of the studied sample units, from 1995 imagery. The analysis of these results indicated the existence of high correlation between biophysical parameters biomass and basal area and calculated digital values, excepting NDVI and PSOL.

ASSUNTO(S)

floresta nacional do tapajos (pa) image processing vegetacao florestas vegetation index satelite landsat processamento de imagens indice de area foliar landsat satellites mapeador tematico (landsat) landsat-5 forest leaf area index indice de vegetacao floresta tropical

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