Banco de sementes do solo em uma toposequência no Parque Nacional da Serra da Bodoquena - Bonito/MS

Abstract

This work has the objective of evaluating the effects of altitudinal dimensions and different light intensities under the composition, abundance and density of seeds from the seed bank of the soil of a fragment of deciduous seasonal forests of the Serra da Bodoquena PARNA. The study was carried out in the southern portion of the Serra da Bodoquena National Park under authorization number 56258-3 at the Chico Mendes Institute for Biodiversity Conservation (ICMBIO) in a toposequence defined by three altitude quotas: 1. Upper Quota - the highest part of the terrain (14º 57 '42,4 "S and 40º 33' 07,5" W), at 560 m altitude; 2. Average (Medium) - corresponds to the intermediate level (21º 07 '26,87 "S and 56º 43' 16.40" W), located at 540 m altitude; and 3. Lower Hill (Base) - lower, lower part of the terrain (21º 07 '20,48 "S and 56º 43' 16.30" W), at 515 m altitude. A total of 90 soil samples with 0.20 x 0.20 m and 5 cm depth measurements were collected, 30 of them for each altitudinal elevation. Samples were placed to germinate in Plena Sol (PS), 50% Shading (SB50%) and Shading (SB70%) trays, each with 10 replicates. Multidimensional non-metric scaling (NMDS) was used to order the observations of the abundance of the species sampled. In addition, multiple variance analysis (MANOVA) was used to test the hypothesis of variation of species abundance in relation to the altitudinal levels and the level of shading. The analysis of variance (ANOVA) was performed to compare the effect of the altitudinal elevation and different levels of shading on the density of the soil seed bank. In the floristic composition of the seed bank were found 26 families, distributed in 37 genera and 39 species. In the soil seed bank for all treatments together were sampled 594 individuals the equivalent to 206.25 plants / m2. The number of species found in the present study as well as seed density in the soil are within the range found for preserved tropical forests. The community structure of the soil seed bank in the PARNA of the Serra da Bodoquena can be explained by the level of shading and not by the altitudinal levels. Seed density was affected by both altitudinal and shade levels. The shade may favor the germination of the seed bank of the Serra da Bodoquena PARNA, a fact that may be related to a lower water loss and consequent humidity increase.