ESTOQUE E DINÂMICA DE BIOMASSA ARBÓREA EM FLORESTA OMBRÓFILA DENSA NA FLONA TAPAJÓS: AMAZÔNIA ORIENTAL

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Abstract

RESUMO A análise das oscilações dos estoques de biomassa em florestas tropicais permite descrever o comportamento desses ecossistemas diante de alterações naturais ou antropogênicas. O objetivo deste trabalho foi avaliar o estoque e a dinâmica de biomassa no período (2007-2010) em Floresta Ombrófila Densa de duas áreas de pesquisa na FLONA - Tapajós: Amazônia oriental, denominadas Área 1 e Área 2, distantes aproximadamente 45 km uma da outra. A biomassa foi estimada através de equação alométrica e medidas de DAP, proveniente de 12 parcelas permanentes, sendo 6 em cada área. Os resultados mostraram que houve diferença significativa no estoque médio anual de biomassa entre a Área 1 (293,19 ± 27,74; 298,21 ± 31,73; 299,60 ± 29,46; 298,11 ± 29,40 Mg.ha-1) e a Área 2 (254,35 ± 69,61; 259,10 ± 70,05; 261,00 ± 69,43; 248,92 ± 61,78 Mg.ha-1). Notou-se variação anual no estoque de biomassa em intervalos de medições superiores a um ano, devido às oscilações na taxa de mortalidade, recrutamento e incremento, além da área basal e abundância dos indivíduos em cada área. A maior concentração de indivíduos ocorreu nas classes diamétricas 10 ≤ DAP ≤ 30 cm, porém, verificou-se que os indivíduos com DAP ≥ 60 cm em concentração menor estocam biomassa equivalente à da classe diamétrica 10 ≤ DAP ≤ 30 cm. Concluiu-se que as oscilações na taxa de mortalidade, recrutamento e incremento, além da abundância e área basal nestes locais afetaram os estoques de biomassa.

Translated abstract

ABSTRACT The analysis of the oscillations of biomass stocks in tropical forests allows us to describe the behavior of these ecosystems in the face of natural or anthropogenic changes. The objective of this study was to evaluate the inventory and dynamics of biomass in the period (2007-2010) in dense rain forest in two areas of research in the National Forest - Tapajos, eastern Amazonia, called Area 1 and Area 2, 45 km distant from each other. The biomass was estimated using allometric equation and DAP, from 12 permanent plots, with six in each area. The results showed a significant difference in annual average stock biomass between Area 1 (293.19 ± 27.74, 298.21 ± 31.73, 299.60 ± 29.46, 298.11 ± 29.40 Mg. ha-1) and Area 2 (254.35 ± 69.61, 259.10 ± 70.05, 261.00 ± 69.43, 248.92 ± 61.78 Mg.ha-1). Besides that, it was noted annual change in stock biomass measurements at intervals of greater than one year due to fluctuations in mortality, recruitment and growth, besides the basal area and abundance of individuals in each area. The highest concentration of individuals occurred in diametric classes DAP 10 ≤ DAP ≤ 30 cm, however, it was verified that individuals with DAP ≥ 60 cm in lower concentration stored biomass equivalent to diametric classes 10 ≤ DAP ≤ 30 cm. We conclude that fluctuations in mortality, recruitment and growth, and abundance and basal area of these sites affected the stock biomass.

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Most cited references 31

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Increasing biomass in Amazonian forest plots.

Andrew Phillips, Norma A S Almeida, Yadvinder Malhi … (2004)

A previous study by Phillips et al. of changes in the biomass of permanent sample plots in Amazonian forests was used to infer the presence of a regional carbon sink. However, these results generated a vigorous debate about sampling and methodological issues. Therefore we present a new analysis of biomass change in old-growth Amazonian forest plots using updated inventory data. We find that across 59 sites, the above-ground dry biomass in trees that are more than 10 cm in diameter (AGB) has increased since plot establishment by 1.22 +/- 0.43 Mg per hectare per year (ha(-1) yr(-1), where 1 ha = 10(4) m2), or 0.98 +/- 0.38 Mg ha(-1) yr(-1) if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is neither confounded by spatial or temporal variation in wood specific gravity, nor dependent on the allometric equation used to estimate AGB. The conclusion is also robust to uncertainty about diameter measurements for problematic trees: for 34 plots in western Amazon forests a significant increase in AGB is found even with a conservative assumption of zero growth for all trees where diameter measurements were made using optical methods and/or growth rates needed to be estimated following fieldwork. Overall, our results suggest a slightly greater rate of net stand-level change than was reported by Phillips et al. Considering the spatial and temporal scale of sampling and associated studies showing increases in forest growth and stem turnover, the results presented here suggest that the total biomass of these plots has on average increased and that there has been a regional-scale carbon sink in old-growth Amazonian forests during the previous two decades.