Fitossociologia,deposição e decomposição de serrapilheira de reflorestamentos em área de encosta, do Parque Estadual do Grajaú – RJ

Abstract

The present study had the objective of evaluate the deposit and decomposition of litter and characterize the phitossociology of two distinctive forestation: heterogeneous plantation and homogeneous plantation with Mimosa caesalpiniifolia(sabiá) specie. Both were implanted as conservacionists actions to recuperate and contain slopes at Grajaú State Park. The fallen material from the trees, were colleted monthly through 10 conics collectors installed in each study area. This material was separated in leaves, branches, seeds, flowers, shell, and others. After this separation, the material was dried and weighted. A part of the leaves fraction was put in litter bags, used to estimate the decomposition of the material. There were installed 9 litter bags in each area containing 10g of the vegetal material. There were taken from the ground in 30, 60 and 90 days, after the installation. The remnants material in each time was milled and sent to analysis of C, N and poliphenois. The analysis of soil fertility was also made and the phitossociology characterization, by the sampling method in parcels. There were identified 21 species, allocated in 19 generous and 10 families, in total of 97 individuals. Fab. Papilionoideae presented most species in total of 6. The species Anadenanthera macrocarpa (18,56%), Mimosa caesalpiniifolia (14,43%), Dalbergia nigra (10,31%), Joannesia princeps (9,28%) e Peltophorum dubium (8,25%) represented 60,83% of the total individuals, presenting higher relative density. The five species with higher relative frequencies were: Anadenanthera macrocarpa (14,55%), Dalbergia nigra (10,91%), Mimosa caesalpiniifolia (10,91%), Peltophorum dubium (10,91%) e Machaerium nyctitans (7,27%). Two of the five species of higher importance, are classified as not-pioneers: Joannesia princeps e Dalbergia nigra. The pattern of deposit apported 3,71 ton/ha and 4,01 ton/há on the homogeneous plantation and heterogeneous plantation, respectively. The leaves fraction presented higher values, 73 %, on the homogeneous plantation and 85 % on the heterogeneous plantation. The decomposition is happening in a faster way on the sabiá plantation. The result of soil fertility are similar to those found on forests soils. The forestation presented a vegetal structure capable of covering the soil and seems to offer protection against erosive process. But, on the homogeneous plantation, this function can be decreased by the higher number of trees on a senescence stage and the absent of a young tree nursery that will come to substitute these trees.