Quantificação e monitoramento da erosão e sobrevivência de espécies florestais em microbacia do Rio Pandeiros

Abstract

Soil and water losses due to water erosion represent a risk of environmental damage and reduction of soil productivity, being one of the main forms of degradation with economic, social and environmental consequences. In this aspect, the survey and mapping of the physical attributes of soil and relief is paramount for the monitoring of the environmental modifications resulting from the anthropic actions occurring in the environment. In addition, it is necessary to adopt simple control strategies that are preferably low cost and easily adopted by rural landowners, such as liming. The objective of this study was to characterize soil physical attributes and soil loss in a Pandeiros river watershed, Januária-MG, determining the spatial variability of these losses and the soil physical attributes, determining in a multivariate manner which attributes most expressively reflect the variance in area, as well as to establish a mathematical model that explains this interrelationship. The objective of this study was to evaluate the survival rate of pioneer and non-pioneer native species as a function of liming in the planting pit upstream of terraces built in the microbasin. The results indicated high soil loss in all areas of the studied microbasin, with higher losses in areas with higher slope, predominance of silt and very fine sand granulometric fractions in detriment to medium sand contents, higher soil electrical conductivity, lower hydraulic conductivity soil saturated and less vegetation cover. The soil mapping in the studied microbasin indicated spatial dependence for most of the soil physical attributes, except for the saturated soil hydraulic conductivity. The multivariate analysis of the soil physical attributes based on the main components explained 95.72% of the variability of the data in the microbasin, providing interpretable components, making it possible to delimit more sensitive attributes in the monitoring of the changes occurred in the soil, being able to be used as parameters to define the strategies of environmental conservation. The levels of medium sand, fine sand and very fine sand are the attributes that most reflect the changes occurring in the soil. In general, there was no effect of liming on plant survival. The species with the highest survival rate were Pau Ferro (Caesalpinia ferrea), Aroeira (Lithraea molleoides) and Gonçalo Alves (Astronium fraxinifolium). However, it is evident the need to find more efficient strategies that can be used in recovery projects of the watershed.