The forest topsoil seed bank as a degraded area rehabilitation strategy / O uso do banco de sementes florestal contido no topsoil como estrategia de recuperação de areas degradadas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

After the nineties, the awareness of the society and enhancement of legal environmental requirements resulted in a greater number of initiatives on degraded lands rehabilitation. The use of topsoil, which contains the forest seed bank and high concentrations of organic matter, has been successfully used, but its application still restrict to flat or low-declivity areas. The local availability of topsoil together with the necessity to rehabilitate slopes with native species community inspired this experimental research. The purpose of this study was to evaluate the topsoil transposition technique to rehabilitate slopes, aiming to identify the main factors acting over the initial succession of these communities and its implications for the rehabilitation process. At an embankment slope with 30° declivity we spread the topsoil collected in a surrounding area just after forest clear cut. Four contention techniques were tested: wood fences forming terraces, horizontal rips, wood fences with green manure and horizontal rips with green manure. The experiment was designed in casualized blocks were each treatment has three 12 x 15m2 replicas, distributed in three blocks. We monitored the regenerating community for 14 months, measuring the individual?s density and the life forms richness. The percentage of exposed soil was measured on the last sampling. Afther 14 months, we registered 150 species including all life forms. In all treatments, the density of individuals was at least five times higher than in the control, ranging from 5,2 to 22,6 ind/m2. The density of individuals was not different among the four treatments, but the rips treatment showed the highest percentage of exposed soil (Chapter 1). The allochtonous soil characteristics, diferent among the experimental blocks, were the main determinants of the structure and floristic composition of regenerating communities. Differences of topsoil soil fertility and seed bank density determined different initial colonization patterns, as well as the community final structure and recovery speed (Chapter 2). Analyzing the whole experimental area, the growth of distinct communities at the same rehabilitated area resulted in a community with heterogeneous structure and floristic composition, which may be interesting for regenerating areas. The results showed that, together with contention techniques, the topsoil use as a source of propagules and organic matter can be efficient on slopes? rehabilitation. The proposed method expands the possibilities of topsoil use, allowing the rehabilitation of slopes and embankments with native species

ASSUNTO(S)

ecological succession solos - degradação sucessão ecologica soil degradation taludes (geografia fisica) solos - recuperação soil remediation slopes (physical geography)

ACESSO AO ARTIGO

Documentos Relacionados