Vegetation fragments located in urban perimeters provide better environmental conditions for biological diversity and human well-being. The aim of this study was to evaluate the Vegetation Coverage Index (VCI) of the urban perimeter of Erechim, RS, between years 2010 and 2015. Mapping was carried out using World View 2 and Pleiades satellites images with spatial resolution of 0.5 m. Significant difference was found between VCI values of 2010 and 2015, as well as a decrease in the recommended rate in the range of 30% per neighborhood. Due to the influence of increased urbanization, there was reduction of 229.98 hectares in the vegetation coverage area of the urban perimeter during the study period. The expansion of urban areas reduced vegetation fragments and has contributed in an effective manner to the disordered occupation of the city, generating negative impacts to the environment and to the quality of life of the local population.

Changes in characteristics of landscape adjacent to forest fragments due to anthropic actions result in increased invasion of non-native species and biodiversity loss. The aim of this study was to evaluate the invasion process of Hovenia dulcis (Thunb.) in forest fragments with different size and shape in order to relate the behavior of the invasion with landscape metrics. As a result, shape and size of the forest fragments do not influence the abundance of H. dulcis. However, a greater number of H. dulcis individuals are concentrated in the edge areas. The canopy, declivity and land use were not associated with the abundance of H. dulcis. The high abundance at the edge of forest fragments highlights the dynamics of the landscape in the study area that are marked by the agricultural matrix. The invasion process occurs regardless of the size and shape of the forest fragments.

The dynamics of land use and cover at different spatial and temporal scales allows us to evaluate changes in landscapes, socioeconomic system and impacts on the natural environment. Land use and land cover changes and socioeconomic activities of the Northern Region of Rio Grande do Sul, Brazil were analyzed over a 20-year scale. Using images from the Landsat 5 sensor TM, land use and land cover maps were obtained for 1991, 2001 and 2011, in which agricultural uses, native vegetation and pasture presented a significant difference between the years. We identified two scenarios for the region: the northern portion presents a reduction in agricultural areas and an increase in pasture and native vegetation, while the southern portion presents a constancy of agricultural areas. The predominant agricultural uses and socioeconomic factors determined the major changes in landscape structure. The effects of these changes resulted in a reduction in the area of agricultural uses and expansion of native vegetation and pasture areas.