Throughout the world, plantations of tree species (native and exotic) for production purposes make up an important part of tree cover, often at the expense of natural forests. Monocultures of exotic and native species generally show a very distinct vegetation physiognomy when compared to natural forests. In the case of abandoned plantations, existing tree regeneration may provide a high potential for restoration of these areas. In this study, we evaluated composition and structure of the adult (upper layer) and regenerative (lower layer) tree component of natural Araucaria forest and of monoculture plantations of Araucaria angustifolia (Bertol.) Kuntze and Pinus sp., and their relationship with edaphic variables and sunshade discontinuity. We aimed to answer the following questions: To which extent do regeneration patterns of native species in the plantations resemble those in natural forests? Does natural regeneration provide a potential for transformation of plantations into natural forests? Does the exotic species regenerate in high abundances, and do other exotic/invasive species establish? Which environmental factors influence regeneration of native species? We expected to find differences in the species composition of the planted areas in relation to the native forest, and more pronounced in the regenerative component. Therefore, the soil parameters and the canopy discontinuity should also be distinct in the distinct vegetation formations. Density of species and tree individuals of the regenerative layer was significantly lower in the plantations, especially in the pine plantation, at the plot level. However, overall species richness was quite similar between vegetation types, with a total of 98 species distributed into 38 families. While light availability did not differ significantly, the soil parameters organic matter, pH, phosphorus and potassium showed significant differences among the vegetation types (in general, lower fertility in plantations). These variables were related to the specific composition of areas, indicating influence of the vegetation on soil conditions and regeneration patterns. Overall, we conclude that restoration of plantations into natural forest based on the existing forest regeneration seems possible, but should be done with caution and under monitoring.

A functional perspective of tree communities is helpful for understanding forest dynamics, especially vegetation recovery after other land uses. Knowledge about ecological filters and survival strategies of trees are also important for the restoration of degraded areas. This study aimed to evaluate the functional composition and structure of adult and regenerative components of natural Araucaria forests, Araucaria plantations and plantations of exotic Pinus in subtropical southern Brazil. Differences in functional diversity and functional richness, and in community weighted mean trait values, including leaf traits and reproductive traits, were analyzed. RLQ analysis was used to assess the association between community structure, plant traits and environmental variables. Clear differences were found for most traits and for functional richness for the regenerative component, while the adult component was more similar among forest types. A clear separation in RLQ ordination associated with trait variation, for the adult component but not for regenerative trees, also indicates that communities are becoming functionally more similar with time. Plantations were shown to function as environmental filters by directly influencing species recruitment, richness and functional diversity. We conclude that passive restoration may be the best strategy for restoration of Araucaria forests.

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.

No abstract

No abstract