Influência da cobertura vegetal sobre a lâmina escoada e a produção de sedimentos em parcelas de erosão no semiárido.

Abstract

The occupation of the Brazilian semiarid region occurred in a overfishing perspective. Population pressure in this region on natural resources leads to environmental degradation, creating a cycle of poverty and misery becoming increasingly vulnerable region in terms of social aspects, economic and environmental. The hypothesis that guides the work is that the vegetation plays a key role on soil conservation and traditional production practices in this region potentiate the degradation of the environment. This work has as objective qualitatively evaluate the influence of vegetation on hydrosedimentological processes, emphasizing the importance of vegetation as soil protective agent in 100,0 m² plot and identifying which type of culture and traditional production practice that offers greater reduction of soil loss. In Sumé Experimental Basin were identified in the period 1982 to 1991, the greatest variation of annual sediment yield when compared to areas without vegetation and land cover of native caatinga, parts 4 and 5, respectively, and 24.95 11399.3 times higher in the plot 4 than in the plot 5. The results obtained in São João do Cariri Experimental Basin of the ray tracing have identified that the vegetation with predominance of Poaceae, plot 2, plays a key role for soil protection, where the annual sediment yield of the parcel 1, deforested, was 3.69 to 42.68 times higher than on plot 2, from 1999 to 2001, a period in which was kept the set-aside scheme in the latter. According to the data obtained in the experimental basins, São João do Cariri and Sumé, the ray tracing was possible to conclude that the vegetation has a significant influence in reducing sediment yield at 100.0 m² plot and that there isn’t a direct relationship between the total annual precipitates, the annual runoff and the annual sediment yield. Among the traditional short-cycle crops, such as corn and bean, increased production of sludge was observed during the cultivation of corn. In the plots with mulch and ground cover, plots 2 and 3, whose slopes are 3.9% and 7.2% respectively, we observed that the annual sediment yield can be up to 83.5 times in the plot than 3 in plot 2. These results show the influence of slope on runoff generation and consequently the production of sediment when the areas are undergoing the same type of vegetation cover and have the same soil type.