Influência da mudança no uso do solo em ecossistemas na Amazônia Sul Ocidental

Abstract

The inadequate land management causes soil degradation, which, if reversible, will require time and resources for recovering. Evaluations of changes in soil properties using soil quality indicators contribute to avoid soils more susceptible to decrease their natural productive capacity. The aim of this study was to verify the influence of changes in land usage on soil properties, using soil quality indicators, and to evaluate the relationship between arbuscular mycorrhyzal fungi with these properties, in ecosystems in south occidental Amazon. The soil sampled was classified as Udult, located in Acre State. There were two sampling periods, one at the end of dry season (August 28th) and the other by the end of the rainy season, in areas with three different plant coverage s: dense primary forest, pasture, and secondary forest. Five soil samples were taken in two depths (0-5 and 5-10cm). In general, there were no differences between the areas for the soil physical properties, except for the aggregate stability. Differences in the chemical properties were correlated with soil organic matter, with highest values in the primary and secondary forest areas. The biological soil properties showed that the microbial biomass was not sensible to usage changes. The arbuscular mycorrhyzal fungi showed highest glomalina amounts in the secondary forest, although the root colonization rate was higher in the pasture. The Pearson correlation analysis allowed to distinguish the best indicators, associated to changes in land usage, since it showed correlation for all attributes. The mycorrhyzal (specially the glomalin indicator) was an efficient soil quality indicator. Multivariate data analysis showed effects of land usage change, where most of the studied attributes were associated with the forest and secondary forest areas. Thus, the most important variables to indicate differences due to changes in land usage were: total carbon, CEC, total nitrogen, glomalin, and free light fraction of soil organic matter. I was concluded that land usage cover change affected soil properties, although not all the studied attributes changed with the modifications in land use.