Enriquecimento de serapilheira com espécies arbóreas aptas para recuperação de áreas degradadas

Abstract

The principal objective of this study was to examine the behavior of an organic soil-litter complex seeded with native tree species, with the intention of optimizing propagation potential, which should accelerate plant succession in degraded land revegetation. The experiment was done in a greenhouse and on benches exposed to open sunlight at the Research Nursery of the Department of Forestry Engineering, Federal University of Viçosa (UFV). For the proposed study, litter samples were collected from the "Mata da Garagem" woods, also located on the UFV campus. A total of 20 samples were collected at randomly distributed points, each sample being composed of 4 subsamples. This was done by placing square wooden frames of 0.25 x 0.25 m (0.0625 m2) on the forest floor and collecting material from within the frame including 5 cm depth of soil. To install the experiment in the nursery, 40 wooden boxes (50 x 50 x 15 cm) were used, 20 of these receiving a layer of 3 cm of substrate which was then covered by organic soil from the woods, and the 20 remaining boxes were filled only with the same substrate. Ten of the 20 boxes that contained the substrate and 10 that contained organic soil were fertilized. Then 20 seeds each of Caesalpinia peltophoroides, Dalbergia nigra, Tabebuia serratifolia and Zeyheria tuberculosa were planted in each box. Half of the 40 boxes were distributed on benches in the greenhouse under 60% shade, and the others were distributed on benches exposed to open sunlight. The experimental design used randomized blocks with subdivided plots with 8 treatments and 5 replications. Plants were irrigated as needed to avoid water stress. The seed bank inventory identified 508 individuals consisting of 38 identified species, 34 genera, and 22 families. Of these, 291 individuals were tree seedlings belong to 20 species, 17 genera and 13 families. The diversity index (H´) value of 2.11 for this experiment is similar to diversity values found in other seed bank studies, whereas the value for equability (J) is higher than for other seed banks. Importance Values (IV) were highest for Cecropia hololeuca (28.9%) and Solamam erianthum (18.7%), the first due to the large number of individuals and the second in consideration of plant size. Evaluation of seed germination for both introduced seeds and seed bank did not show any differences for the environments tested. The non-fertilized soils had a higher percentage of germinated seeds in comparison to other soils. In general, all the plants, both from seed bank or introduced seeds, were more developed in the shaded environment. Despite inhibiting germination of introduced species, fertilization was fundamentally important for the development of all species. Results show the efficiency of enriching seed banks and confirm the potential of this technique for revegetating degraded areas.