Mudanças nos padrões espaciais de fragmentos remanescentes em uma zona de ecótono

Abstract

Forest fragmentation caused by the substitution of native vegetation for activities such as agriculture and urban expansion has as consequence fragmentation and loss of habitats. The Mourão river watershed houses two important biomes considered as hotspots of biodiversity and that reflect the intensive process of forest fragmentation. Studies about multitemporal scales analysis are relevant to understand the changes in forest patterns and are fundamental for trend predicting in landscape dynamics caused by anthropic activities. The use of GIS and landscape ecology metrics as monitoring tools of landscape dynamics can make it possible to diagnose the current situation of forest remnants and Conservation Units. Thus, the present study aimed to verify the effects of fragmentation in the Mourão River watershed, Paraná, from 1991 to 2016, by using Landsat satellite images and of landscape ecology metrics analysis. The satellite images treatment and classification were performed based on the calculation of the mean NDVI index by the SPRING® software; then, it was identified the index range that represented the watershed forest cover between 1991 and 2016. For the calculation of the landscape metrics, it was performed using FRAGSTATS® software. In general, although the watershed has presented 97% of forest fragments smaller than 50 ha, these had the mean size area increased in 72.9%, a reduction in number and an increase in the mean shape index of 1.3 in 1991 to 1, 5 in 2016. The watershed presented a 64.7% increase in edge density and a reduction of 35.6 meters for the nearest neighbor. Also, it was observed that the core area decreases according to the increasing edge effect depth assumption. The use of remote sensing and landscape ecology metrics enabled the rapid and efficient mapping of the current situation of fragmentation process in the watershed, suggesting that the fragments undergo a expansion process and reduction of the isolation degree, if compared to 1991.