Avaliação da regeneração natural e do banco de sementes do solo de áreas à jusante da IHE de Camargos, Itutinga, MG

Abstract

Understanding successional processes in ecosystems is very important to the success of their management, whatever their purpose may be. Some of the required information are the knowledge of natural regeneration and the stock of viable seeds in the soil, i.e. the soil seed bank. Such information allow to infer about the succession stage of the fragments and their responses to anthropic or natural changes. Therefore, the objective of this study was to evaluate the natural regeneration and the soil seed bank, at three different times (Dec/2011, Apr/2012, Aug/2012), in areas downstream from the Hydroelectric Dam of Camargos, in the municipality of Itutinga, MG. Three areas were evaluated: one is a native fragment of the Semideciduous Forest used as a reference (RE); the others are environmental afforestation areas with different backgrounds, one classified as degraded (DE): it was used as a borrow area for the construction of the Hydroelectric Dam, with its vegetation totally destroyed and exposure of the C horizon of the soil; the other was classified as disturbed (PE): it was used as a material deposit at the time of the Hydroeletric Dam of Carmargos construction , had its vegetation removed, but no change was observed in the soil. Both have been under a restoration process for 19 years, which consisted of reshaping land and the execution of an enrichment planting. This study was divided into three chapters: in the second one are the studies related to natural regeneration and, in the third, the studies related to the soil seed bank. With the evaluations, it was observed that the areas DE and PE do not resemble RE on the floristic composition of natural regeneration while, among themselves, they are similar. The Shannon diversity index shows that their values are good, compared to other studies in similar conditions. The soil seed bank shows that, analyzing only tree-habit species, the floristic composition of DE and PE is similar to RE. Melinis minutiflora is a species that can compromise the advancement of succession in the DE area, since its significant presence in the three evaluations performed is observed. Studies like these are of great importance since, besides basing the understanding in relation to successional processes, provide essential information for decision-making related to the need for further interventions in areas that are under a recovery process.