Mudanças espaciais dos pequenos elementos da paisagem da Mata Atlântica mineira ao longo de quatro anos

Abstract

Habitat fragmentation has been shown as a key issue for biodiversity conservation. Most studies are focused on the importance of large fragments. However, increasing of fragmentation implies in a greater partitioning of the landscape, and consequently a rising in the small landscape’s elements. Nowadays, there are only a few studies on small elements. In our study, small landscape elements (SLEs) are classified as: small fragments (areas < 10 hectares), linear elements (trees lines, fences, hedgerows) and scattered trees. The study aims to evaluate the dynamics and its drivers of each small landscape elements in the Atlantic Forest of Minas Gerais. The thesis content was divided into four chapters: (I) a review of the main topics studied; (II) small fragments; (III) trees lines; (IV) scattered trees. The study was carried out from 26 images collection of the Rapideye sensor considering the years of 2011 and 2015. The images dimensions are of 12 x 12 km, corresponding to Atlantic Forest areas situated in Minas Gerais state. We performed a supervised classification considered six classes. For the vegetation class, elements with a width of less than 15 meters were classify as linear elements. The remaining elements of the vegetation class with width greater than 15 meters were classified as small fragments (areas between 0.04 and 10 hectares), areas larger than 10 hectares of vegetation, and areas smaller than 0.04 hectares. In addition, we manually classified the scattered trees delimiting four quadrants in each image. We used variables of climate, landscape, terrain, and soil to model the dynamic variables of each SLE. We found a greater gain than loss in area of small fragments, being the major rates of gain found in Vale do Rio Doce region. The main drivers for small fragments are landscape characteristics. We found loss of the trees lines, mainly in the southern regions of the Minas Gerais state. Meanwhile, the largest increments in tree line length were in the north region of the state. The main predictors for changes in the tree line were annual precipitation, urbanization, region, small fragments, and number of corridors. We identified that there was an increase of the scattered trees in the whole Atlantic Forest in Minas Gerais state. The greatest gains were found in border regions to Atlantic Forest areas, and the smallest gains in bordering areas to the Brazilian Savanna. The scattered trees change was predicted by climatic characteristics and increase in areas smaller than 0.04 hectares. Overall, we found an increase in small fragments and isolated trees, however, there was a loss of trees lines. The biggest gains of SLEs are concentrated in the north and center of Minas Gerais state, while greater losses are found at south region. Our study provides great insights to the science improvement since the study brings facts and knowledge not reported yet. In addition, the study findings lead to the application of public policies for the restoration and conservation of SLEs in the Atlantic Forest.