Dinâmica de florestas manejadas e sob exploração convencional na Amazônia Oriental
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
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Descrição
Esta tese compara as dinâmicas de uma floresta explorada com exploração de impacto reduzido (EIR) com outra explorada convencionalmente (EC) numa propriedade denominada Fazenda Agrosete (3º S, 50º W), em Paragominas, no nordeste do Estado do Pará. Os estudos foram realizados numa área de 210 ha, dos quais 75 ha foram explorados convencionalmente, 105 ha foram explorados com exploração de impacto reduzido e 30 ha não explorados (testemunha). A área foi explorada em 1993 e monitorada até 2000. A avaliação da dinâmica das espécies madeireiras nesses três tratamentos foi feita em 10 clareiras selecionadas em cada tratamento. A análise dos efeitos dos tratamentos silviculturais sobre a regeneração de valor madeireiro foi feita em 60 clareiras selecionadas aleatoriamente em cada tratamento. A análise da diversidade de espécies arbóreas foi feita numa área de 5,25 ha delimitada em cada tipo de exploração. E, finalmente, para analisar a dinâmica de espécies arbóreas estabeleceram-se 49 parcelas de 0,5 ha em cada tratamento. Os resultados demonstraram que: i) considerando a regeneração abaixo de 10 cm de DAP não existiram diferenças significativas na dinâmica da regeneração entre as clareiras de exploração de impacto reduzido e as de exploração convencional; ii) os tratamentos silviculturais causaram efeitos positivos sobre o crescimento de espécies de valor comercial presente nas clareiras crescendo de 75% a 115% a mais do que as não tratadas; iii) considerando as espécies arbóreas acima de 10 cm de DAP, a diversidade de espécies reduziu com a colheita e tem apresentado uma boa recuperação, inclusive na área explorada de madeira convencional; iv) a mortalidade de árvores foi menor e o recrutamento foi maior no tratamento de exploração de impacto reduzido em comparação com os tratamentos de exploração convencional e com a testemunha; v) a taxa anual de mortalidade na área de exploração convencional foi 70% superior ao da área com exploração de impacto reduzido; e vi) o crescimento das árvores no tratamento exploração de impacto reduzido foi 5,5 vezes maior do que o crescimento no tratamento de exploração convencional. Esses resultados demonstram que a exploração de impacto reduzido reduz bastante os efeitos negativos sobre a diversidade de espécies, além de promover o crescimento das árvores. Dessa maneira, as florestas exploradas com técnicas de exploração de impacto reduzido se recuperarão num período relativamente menor do que as florestas exploradas convencionalmente, ao mesmo tempo em que estarão mantendo a conservação da biodiversidade florestal. Nossa conclusão é que a exploração de impacto reduzido pode ser uma alternativa ao modelo de exploração atualmente praticado na Amazônia.
This thesis compares the dynamics of forest harvested using reducing impact logging (RIL) and conventional logging forest (CL) at the property known as Fazenda Agrosete (3º S, 50º W), in Paragominas, in the north-east of the State of Pará. The studies were carried out in an area of 210 ha, of which 75 ha were conventional logging, 105 ha were logged using reducing impact logging (RIL) and 30 ha was an unlogged control. The area was harvested in 1993 and monitored until 2000. The evaluation of the dynamics of timber species in these three treatments was carried out in 10 gaps selected in each treatment. The analysis of the effect of silvicultural treatments on regeneration of timber value was done in 60 randomly selected gaps were for each species. The analysis of tree species diversity was done in an area of 5.25 ha delimited for each type of logging. And, finally, to analyse the dynamics of tree species 49 lots, each measuring 0.5 ha were established in each treatment. The results demonstrate that: i) considering regeneration below 10 cm DBH there were no significant differences in regeneration dynamics between the gaps in the reducing impact logging (RIL) area and those in the conventional logging area; ii) the silvicultural treatments caused positive effects on growth of commercially valuable species present in the gaps; grew 75% a 115% more than non-managed regeneration; iii) considering tree species above 10 cm DBH, species diversity was reduced with harvest and has shown good recovery, including in the conventional harvested area; iv) tree mortality was lower and recruitment was higher in the reducing impact logging (RIL) treatment in comparison with conventional logging and witness treatments; v) the annual mortality rate in the conventional logging area was 70% higher than that of the area under reducing impact logging (RIL); and vi) growth of trees in the management treatment was 5.5 times higher than growth under the conventional logging treatment. These results demonstrate that reducing impact logging (RIL) considerably reduces negative effects on species diversity, besides promoting tree growth. In this way, forests logged using reducing impact logging (RIL) techniques will recover in a relatively shorter period than forests that are conventional logging, while at the same time maintaining forest biodiversity. Our conclusion is that reducing impact logging (RIL) can be an alternative to the logging model currently practised in Amazon.
This thesis compares the dynamics of forest harvested using reducing impact logging (RIL) and conventional logging forest (CL) at the property known as Fazenda Agrosete (3º S, 50º W), in Paragominas, in the north-east of the State of Pará. The studies were carried out in an area of 210 ha, of which 75 ha were conventional logging, 105 ha were logged using reducing impact logging (RIL) and 30 ha was an unlogged control. The area was harvested in 1993 and monitored until 2000. The evaluation of the dynamics of timber species in these three treatments was carried out in 10 gaps selected in each treatment. The analysis of the effect of silvicultural treatments on regeneration of timber value was done in 60 randomly selected gaps were for each species. The analysis of tree species diversity was done in an area of 5.25 ha delimited for each type of logging. And, finally, to analyse the dynamics of tree species 49 lots, each measuring 0.5 ha were established in each treatment. The results demonstrate that: i) considering regeneration below 10 cm DBH there were no significant differences in regeneration dynamics between the gaps in the reducing impact logging (RIL) area and those in the conventional logging area; ii) the silvicultural treatments caused positive effects on growth of commercially valuable species present in the gaps; grew 75% a 115% more than non-managed regeneration; iii) considering tree species above 10 cm DBH, species diversity was reduced with harvest and has shown good recovery, including in the conventional harvested area; iv) tree mortality was lower and recruitment was higher in the reducing impact logging (RIL) treatment in comparison with conventional logging and witness treatments; v) the annual mortality rate in the conventional logging area was 70% higher than that of the area under reducing impact logging (RIL); and vi) growth of trees in the management treatment was 5.5 times higher than growth under the conventional logging treatment. These results demonstrate that reducing impact logging (RIL) considerably reduces negative effects on species diversity, besides promoting tree growth. In this way, forests logged using reducing impact logging (RIL) techniques will recover in a relatively shorter period than forests that are conventional logging, while at the same time maintaining forest biodiversity. Our conclusion is that reducing impact logging (RIL) can be an alternative to the logging model currently practised in Amazon.
Palavras-chave
Regeneração, Manejo florestal, Floresta tropical, Exploração de impacto reduzido, Exploração convencional, Tratamentos Silviculturais, Diversidade, Crescimento, Silvicultural treatments, Regeneration, Conventional logging, Reducing impact logging, Growth, Forest management, Diversity, Tropical forest