Competição entre árvores em florestas tropicais
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Data
2014-02-27
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Universidade Federal de Viçosa
Resumo
A competição é uma interação entre indivíduos, provocada por uma exigência compartilhada para um recurso de provisão limitada, conduzindo a uma redução no crescimento e sobrevivência do indivíduo menos adaptado. A competição é um importante fator que estrutura comunidades vegetais, porém mensurar competição em florestas tropicais é uma tarefa que tem se demonstrado árdua e pouco efetiva pelos métodos usuais embasados em distâncias e abundâncias inerentes ao ambiente e a alta densidade e diversidade encontradas nestas florestas. Pelas dificuldades inerentes à mensuração de competição em florestas naturais, este estudo teve o objetivo de avaliar a competição por meio de diferentes metodologias para verificar a ocorrência de competição em uma floresta tropical por intermédio do vigor competitivo e da densidade de indivíduos. As hipóteses de trabalho foram que a alometria é mais efetiva na mensuração de competição entre árvores de florestas tropicais que o número de indivíduos e que as maiores árvores da comunidade dirigem o processo competitivo nas florestas tropicais. Para isso foram selecionadas três áreas de estudos: I) Floresta do Seu Nico (FSN, localizada no município de Viçosa, Minas Gerais. II) Mata da Biologia (MDB), localizada no município de Viçosa, Minas Gerais III) Floresta de Tabuleiro de Caravelas (FTC), localizada no município de Caravelas, Bahia. Para a área da FSN e MDB, foram alocadas 100 parcelas contínuas (grid) de 10 x 10 metros (100 m2), totalizando 1 ha. Para a área da FTC, foram alocadas 50 parcelas de 10x10m2 totalizando 0,5 ha. Foram amostrados todos os indivíduos nas parcelas e que apresentaram circunferência a altura do peito (CAP) a 1,30 metros do solo com circunferência do tronco superior ou igual a 10 cm para a FSN e superior ou igual 15 cm para MDB e FTC, o que vale respectivamente a um diâmetro a altura do peito (DAP) igual ou superior a 3,2cm e 4,8 cm. Para inferir a competição entre as árvores, foram feito os seguintes estudos: O vizinho mais próximo; CAP, DAP ou Área Basal como medida do vigor Competitivo; Verificação da competição através do vigor competitivo; A influência do vigor competitivo na competição; As relações do aumento do CAP e a influência do indivíduo mais vigoroso; A regressão do método do vizinho mais próximo não foi significativa; O CAP se mostrou a melhor medida para se usar como vigor competitivo. A correlação para verificar a competição através do vigor competitivo foi significativa para as três áreas de estudo. As correlações para verificar a competição pela influência do vigor competitivo na competição não foi significativa para nenhuma área. Todas as correlações de incremento demonstrando o aumento do CAP foram significativas. As correlações mostrando a influência do indivíduo mais vigoroso foram significativas. Os resultados encontrados demonstraram que o método do vizinho mais próximo foi inadequado para Florestas Tropicais, que a mensuração do vigor competitivo por meio do CAP, demonstrou significativo efeito dos indivíduos de maior vigor competitivo sobre as demais árvores das parcelas. Encontramos, também, significativo efeito do CAP médio das árvores das parcelas na exclusão competitiva, sendo que quanto maior o CAP médio, menor o número de indivíduos nas parcelas. Além de demonstrar uma influência significativa das grandes árvores e do CAP médio no processo competitivo da comunidade, o método mostrou que a CAP é uma medida adequada para mensuração do vigor competitivo e para avaliação da competição. Outra resposta foi que embora o efeito das árvores dominantes seja importante na competição da comunidade, não houve significância na relação entre o CAP do maior indivíduo sobrevivente nas parcelas e o número de indivíduos nas parcelas. Contudo, houve significância na relação negativa entre o número de indivíduos nas parcelas e o CAP médio nas parcelas.Pela relação ser negativa, o maior vigor competitivo médio sugere uma forte exclusão competitiva como efeito do conjunto de indivíduos mais competitivos e não pelo efeito de um único competidor dominante.
Competition is an interaction between individuals, brought about by a shared requirement for a resource in limited supply, leading to a reduction in the growth and survival of less adapted individual. Competition is an important factor structuring plant communities, however measuring competition in tropical forests is a task that has proved difficult and less effective by the usual methods grounded in abundances and distances inherent to the environment and the high density and diversity found in these forests. The difficulties inherent in measuring competition in natural forests, this study aimed to evaluate the competition by using different methods to verify the occurrence of competition in a tropical forest through the competitive vigor and density of individuals. The working hypothesis was that the allometry is more effective in measuring competition among tropical forests that the number of individuals and that the largest trees in the community drive the competitive process in tropical forest trees. For this three study areas were selected: I) Floresta do Seu Nico (FSN), located in Viçosa, Minas Gerais. II) Forest Biology (MDB), located in Viçosa, Minas Gerais. III) Forest Tabuleiro de Caravelas (FTC), located in the municipality of Caravelas, Bahia. For the area of FSN and MDB, 100 continuous parcels (grid) of 10 x 10 meters (100 m2) were placed, totaling 1 ha. For the area of FTC, 50 plots of 10x10m 2 totaling 0.5 ha were allocated. All individuals were sampled in plots and presented circumference at breast height ( CBH) to 1.30 meters from the ground to the upper trunk circumference ≥ 10 cm for FSN and greater than or equal to 15 cm MDB and FTC , the worth respectively a diameter at breast height ( DBH ) greater than or equal to 3.2 cm and 4.8 cm . To infer the competition between trees, the following studies were done: The nearest neighbor; CAP, DAP or basal area as a measure of competitive force; Checking the competition through competitive force; The influence of competitive force in competition; The relationship of increased CAP and the influence of stronger individual; Regression of nearest neighbor method was not significant; The CAP proved the best measure to use as a competitive force. The correlation to verify the competition through competitive effect was significant for the three study areas. The correlations to verify the influence of competition competitive force in competition was not significant for any area. All correlations demonstrating the incremental increase in the CAP were significant. Correlations showing the influence of the stronger individual were significant. The results showed that the method of the nearest neighbor was inappropriate for Tropical Forests, the measurement of the competitive force through the CAP, significant effect of individuals of greater competitive effect on other portions of the trees. We also found a significant effect of CAP medium trees in the plots of competitive exclusion, and the higher the average CAP, the smaller the number of individuals in the plots. Besides demonstrating a significant influence of the large trees and the average CAP in the competitive process of the community , the method showed that the CAP is an appropriate measure to measure the competitive effect and to evaluate the competition. Another response was that although the effects of the dominant trees are important in the community competition, there was no significant relationship between the CAP of the largest surviving individual in the plots and the number of individuals in the plots. However, there was a significant negative relationship between the number of individuals in the plots and the average CAP in installments. The relationship is negative, the highest average competitive effect suggests a strong competitive exclusion as an effect of all the most competitive individuals and not by the effect of a single dominant competitor.
Competition is an interaction between individuals, brought about by a shared requirement for a resource in limited supply, leading to a reduction in the growth and survival of less adapted individual. Competition is an important factor structuring plant communities, however measuring competition in tropical forests is a task that has proved difficult and less effective by the usual methods grounded in abundances and distances inherent to the environment and the high density and diversity found in these forests. The difficulties inherent in measuring competition in natural forests, this study aimed to evaluate the competition by using different methods to verify the occurrence of competition in a tropical forest through the competitive vigor and density of individuals. The working hypothesis was that the allometry is more effective in measuring competition among tropical forests that the number of individuals and that the largest trees in the community drive the competitive process in tropical forest trees. For this three study areas were selected: I) Floresta do Seu Nico (FSN), located in Viçosa, Minas Gerais. II) Forest Biology (MDB), located in Viçosa, Minas Gerais. III) Forest Tabuleiro de Caravelas (FTC), located in the municipality of Caravelas, Bahia. For the area of FSN and MDB, 100 continuous parcels (grid) of 10 x 10 meters (100 m2) were placed, totaling 1 ha. For the area of FTC, 50 plots of 10x10m 2 totaling 0.5 ha were allocated. All individuals were sampled in plots and presented circumference at breast height ( CBH) to 1.30 meters from the ground to the upper trunk circumference ≥ 10 cm for FSN and greater than or equal to 15 cm MDB and FTC , the worth respectively a diameter at breast height ( DBH ) greater than or equal to 3.2 cm and 4.8 cm . To infer the competition between trees, the following studies were done: The nearest neighbor; CAP, DAP or basal area as a measure of competitive force; Checking the competition through competitive force; The influence of competitive force in competition; The relationship of increased CAP and the influence of stronger individual; Regression of nearest neighbor method was not significant; The CAP proved the best measure to use as a competitive force. The correlation to verify the competition through competitive effect was significant for the three study areas. The correlations to verify the influence of competition competitive force in competition was not significant for any area. All correlations demonstrating the incremental increase in the CAP were significant. Correlations showing the influence of the stronger individual were significant. The results showed that the method of the nearest neighbor was inappropriate for Tropical Forests, the measurement of the competitive force through the CAP, significant effect of individuals of greater competitive effect on other portions of the trees. We also found a significant effect of CAP medium trees in the plots of competitive exclusion, and the higher the average CAP, the smaller the number of individuals in the plots. Besides demonstrating a significant influence of the large trees and the average CAP in the competitive process of the community , the method showed that the CAP is an appropriate measure to measure the competitive effect and to evaluate the competition. Another response was that although the effects of the dominant trees are important in the community competition, there was no significant relationship between the CAP of the largest surviving individual in the plots and the number of individuals in the plots. However, there was a significant negative relationship between the number of individuals in the plots and the average CAP in installments. The relationship is negative, the highest average competitive effect suggests a strong competitive exclusion as an effect of all the most competitive individuals and not by the effect of a single dominant competitor.
Descrição
Palavras-chave
Florestas tropicais, Árvores - Competição (Biologia), Ecologia
Citação
MOREIRA, Luís Cláudio Benevides. Competição entre árvores em florestas tropicais. 2014. 20f. Dissertação (Mestrado em Ecologia) - Universidade Federal de Viçosa, Viçosa. 2014.