Deposição, acúmulo e decomposição de serapilheira em área de Caatinga preservada

Abstract

Em qualquer ecossistema florestal existe uma forte interação entre a vegetação e o solo, que se expressa no processo cíclico de entrada e saída de matéria orgânica do mesmo. A ciclagem de nutrientes via serapilheira é considerada o meio mais importante de transferência de elementos essenciais da vegetação para o solo. No presente estudo objetivou-se estimar a produção, acúmulo e a taxa de decomposição da serapilheira em Unidade de Conservação, no semiárido da Paraíba. Para avaliar a produção de serapilheira foram utilizados 20 coletores de 1,0 m x 1,0 m, com fundo de tela de náilon, sendo as coletas realizadas mensalmente. A serapilheira coletada foi separada nas frações folhas, galhos, material reprodutivo e miscelânea. Para a quantificação do estoque de serapilheira acumulada foi utilizada moldura metálica com dimensões de 0,5 m x 0,5 m, que era lançada de forma aleatória. A taxa de decomposição da serapilheira foi estimada através produção anual de serapilheira e média anual da serapilheira acumulada. Foi calculado, também, o tempo médio de renovação estimado por 1/K e os tempos necessários para que ocorra decomposição de 50% e 95% da serapilheira. O delineamento experimental utilizado para análise da deposição da serapilheira foi em blocos casualizados com 20 repetições, com os tratamentos em arranjo fatorial 15 x 3, e comparação de médias pelo teste de Tukey. A deposição total de serapilheira em durante os três períodos de estudo foi de 3.275,20 kg ha-1, a fração folha contribuindo com 72,9%, galho com 14,6%, material reprodutivo com 12,3% e miscelânea com 0,8%. O coeficiente de decomposição obtido foi de 0,58. Conclui-se, portanto, que em todos os períodos estudados, a fração folha foi a que constituiu com maior percentual na serapilheira. A deposição de serapilheira na caatinga obedeceu à sequência: folha > galho > material reprodutivo > miscelânea. A decomposição da serapilheira na caatinga é mais lenta de que em floresta tropical úmida.

In any forest ecosystem there is a strong interaction between vegetation and soil, which is expressed in the organic matter input and output cyclical process. The cycling of nutrients through litter is considered the most important means of transfer of essential elements of the vegetation to the ground. The present study aimed to estimate the production, accumulation and decomposition rate of litter in the Conservation Unit, in the semi-arid of Paraiba. To evaluate the litterfall we used 20 1.0m x 1.0 m, with bottom of nylon mesh, and the collections were done monthly. The litter was collected in separate fractions leaves, branches, reproductive material, and miscellaneous. To quantify the stock of accumulated litter we used metal frame with dimensions of 0.5m x 0.5 m, which was launched at random. The decomposition rate of litter was estimated by annual litterfall and annual average accumulated litter. We also calculated the average time of renovation estimated by 1 / K and the time required for decomposition of 50% and 95% of the litter. The experimental design used for analysis of the deposition of the litter was in randomized blocks with 20 repetitions with a factorial arrangement of treatments in 15 x 3, and comparison of means by Tukey test. The total deposition of litter in three periods during the study was 3275.20 kg ha-1, the fraction contributing 72.9% leaf, twig with 14.6%, 12.3% with reproductive material and Miscellaneous with 0 8%. The decomposition coefficient obtained was 0.58. We conclude, therefore, that in all periods studied, the leaf fraction formed the highest percentagIn any forest ecosystem there is a strong interaction between vegetation and soil, which is expressed in the organic matter input and output cyclical process. The cycling of nutrients through litter is considered the most important means of transfer of essential elements of the vegetation to the ground. The present study aimed to estimate the production, accumulation and decomposition rate of litter in the Conservation Unit, in the semi-arid of Paraiba. To evaluate the litterfall we used 20 1.0m x 1.0 m, with bottom of nylon mesh, and the collections were done monthly. The litter was collected in separate fractions leaves, branches, reproductive material, and miscellaneous. To quantify the stock of accumulated litter we used metal frame with dimensions of 0.5m x 0.5 m, which was launched at random. The decomposition rate of litter was estimated by annual litterfall and annual average accumulated litter. We also calculated the average time of renovation estimated by 1 / K and the time required for decomposition of 50% and 95% of the litter. The experimental design used for analysis of the deposition of the litter was in randomized blocks with 20 repetitions with a factorial arrangement of treatments in 15 x 3, and comparison of means by Tukey test. The total deposition of litter in three periods during the study was 3275.20 kg ha-1, the fraction contributing 72.9% leaf, twig with 14.6%, 12.3% with reproductive material and Miscellaneous with 0 8%. The decomposition coefficient obtained was 0.58. We conclude, therefore, that in all periods studied, the leaf fraction formed the highest percentage in the litter. Litterfall in the caatinga followed the order: leaf> branch> reproductive material> miscellaneous. The decomposition of litter in the caatinga is slower than in rainforest. e in the litter. Litterfall in the caatinga followed the order: leaf> branch> reproductive material> miscellaneous. The decomposition of litter in the caatinga is slower than in rainforest.