Estudos das alterações florísticas e estruturais em áreas de exploração florestal permitem avaliar os impactos e fornecem informações básicas para o manejo florestal racional. Nesse contexto, as dinâmicas florística e estrutural foram avaliadas em uma floresta tropical, dez anos após sua exploração madeireira. O experimento foi executado em 200 ha do Campo Experimental da Embrapa Amazônia Oriental, em Moju, PA, onde foi feita a exploração madeireira. No entorno de nove clareiras selecionadas foram instaladas faixas de 10 m x 50 m, divididas em parcelas quadradas de 10 m de lado (1 a 5), onde foram inventariadas as plantas com DAP > 5 cm. Nas parcelas 1, 3 e 5 e no centro da clareira foram instaladas subparcelas de 2 m x 2 m, onde foram medidos os indivíduos com altura < 10 cm e DAP < 5 cm. O monitoramento da floresta abrangeu um período de nove anos e meio, entre março de 1998 e outubro de 2007. A análise estrutural foi feita com base nos parâmetros de abundância, frequência, dominância, regeneração natural, posição sociológica e índice de valor de importância ampliado (IVIA), sendo comparadas as estruturas da floresta dos anos de 2007 e 1998. Dez anos após a exploração, a alta heterogeneidade foi mantida e aumentou no povoamento mais jovem, graças ao ingresso de espécies com forte demanda por luz. Entretanto, a composição florística e a estrutura da floresta manejada ainda mostram grande importância de espécies que, em florestas não perturbadas, não teriam grande expressão em termos de IVIA. Palavras Structure of a tropical rainforest 10 years after selective logging in Moju-ParáStudies of the floristic and structural dynamics in forest exploitation areas allow to assess the impacts and provide basic information for the rational forest management. In this context, the floristic and structural dynamics were evaluated in a rainforest, ten years after its logging. The experiment was performed in 200 ha of the Experimental Field of Embrapa Eastern Amazon, in Moju -PA, where logging was done. Around the nine gaps selected, 10 m x 50 m tracks were installed, divided into square plots of 10 m side (1-5), where the plants with DBH > 5 cm were inventoried. In plots 1, 3 and 5 and in the gap center subplots of 2 m x 2 m were installed where individuals with height < 10 cm and DBH < 5 cm were measured. The forest monitoring covered a period of 9.5 years, between March 1998 and October 2007. The structural analysis was based on the parameters of abundance, frequency, dominance, natural regeneration, sociological position and extended importance value index (EIVI) and compared the forest structures in 2007 and 1998. Ten years after logging, the high heterogeneity was maintained and increased in the younger population, due to the entry of species with strong demand for light. However, the floristic composition and structure of the managed forest still show great importance of species that, in undisturbed forests, would not have great expression in terms of EIVI.
Avaliou-se a sobrevivência e o crescimento de mudas de Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby (paricá) plantadas aleatoriamente em três tamanhos de clareiras causadas pela exploração florestal de impacto reduzido, na Fazenda Rio Capim, no município de Paragominas, Pará. As medições foram realizadas em cinco ocasiões (2005, 2006, 2008, 2010 e 2011). As clareiras foram classificadas em pequenas (200-400 m²), médias (401-600 m²) e grandes (> 600 m²). Com base na sobrevivência e no crescimento de mudas, nos seis primeiros anos após o plantio, sugere-se Schizolobium parahyba var amazonicum para plantios em clareiras, com áreas a partir de 200 m2 , causadas por exploração florestal de impacto reduzido.
RESUMOAvaliou-se a sobrevivência e o crescimento em altura de indivíduos da regeneração natural de Astronium gracile Engl., em diferentes tamanhos de clareiras ocasionadas pela exploração florestal no município de Paragominas, Pará. As mudas de Astronium gracile foram selecionadas aleatoriamente nas clareiras. As medições foram feitas nos anos de 2005, 2006, 2008 e 2010. As clareiras foram classificadas em pequenas (200 -400 m²), médias (401 -600 m²) e grandes (> 600 m²). As mudas de regeneração natural de Astronium gracile, espécie considerada tolerante à sombra, se beneficiaram da abertura de clareiras, principalmente das maiores, para crescer em altura e para sobreviver, demonstrando potencial para uso em sistemas silviculturais, visando aumentar o valor comercial da floresta para futuras colheitas de madeira. Palavras-chave: floresta de terra firme; tratamento silvicultural; manejo florestal. ABSTRACTThe survival and the height growth rates of individuals from the natural regeneration of Astronium gracile Engl. were evaluated in different gap sizes after logging in the municipality of Paragominas, Pará state. Seedlings of Astronium gracile were randomly chosen in the gaps. The measurements were performed in 2005, 2006, 2008 and 2010. The canopy gaps were classified as small gaps (200-400 m²), medium gaps (401-600 m²) and large gaps (> 600 m²). The seedlings from natural regeneration of Astronium gracile, considered as a shade-tolerant species, were favored by the open gaps, mainly large gaps, for growing up and surviving, showing potential for using in silvicultural systems to increase the commercial value of the forest and to allow future harvests.
Research is needed to subsidize foresters to manage the forest for better use of wood. To help in the research, analyzing the diameter distribution, the species can be grouped according to their characteristics concerning the diameter growth and projected their future growth, determining if they reached the expected diameter before the cutting cycle stipulated by law. The aim of the present research was to diametric distribution predict by a size class distribution method, by ecological groups. The study was carried out in Moju, PA. Nine clearings were selected, around which 4 sample plots of 10 x 50 m were installed, starting at the border of the clearing into the forest in the north, south, east and west directions. All individuals with DBH (diameter at breast height) ≥ 5 cm were measured. The species were grouped into tolerant, intermediate and intolerant regarding the demand for solar radiation. The methods tested were Transition Matrix and Moving Ratio, using data from 1998 and 2001 and making projections for 3 year periods (2007 and 2010). The efficiency of the projections was tested using the Kolgomorov-Smirnov adhesion test. The projections performed by the methods did not present a significant difference between the actual and projected values. Based on the results it is recommended to use the Transition Matrix for the prognosis of the diametrical distribution of individuals belonging to the group of tolerant and intermediate species and it is indicated to use both methods for intolerant species.
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