RESUMO Structure and Conservation of a Stretch of Seasonal Forest in Pirai-RJ ABSTRACTThis study aimed the floristic and structural characterization of a stretch of seasonal forest in the Municipality of Pirai, State of Rio de Janeiro, in order to determine its successional stage. The Parque Municipal da Mata do Amador has an area of 16.4 ha (22º37'S and 43º53'W), where 15 plots of 10 × 10 meters were installed. Plants with DAP ≥ 5cm were measured, which totalized 176 specimens, encompassing 24 families, 46 genera and 51 species. The richest family was Fabaceae. The most abundant genera were Cupania L., Casearia Jacq and Eugenia L. The species with the highest importance value was Sorocea bonplandii. It was demonstrated tha the Mata do Amador has considerable species diversity (H '= 3.517 natsind-1 ) and high equability (J' = 0.884), classified as a secondary forest stretch in a intermediate stage of regeneration.

In the Rio de Janeiro State, the Atlantic Forest is restricted to small fragments, responsible for the maintenance of environmental services. These fragments occur on steep slopes dominated by concave and convex pedoforms, capable of changing the local microclimate conditions. To preserve these communities, it is necessary to determine the level of influence of these pedoforms on forests structure and species distribution. Thus, we performed a phytosociological study and installed a set of four sensors to determine the monthly mean of air temperature and relative humidity in concave and concave pedoforms. The forest structure and the microclimate averages are compared by the Levene's T-test. We observed differences between microclimatic average, importance value indexes (IVIs) and total height, indicating that microclime variations can influence the structure and composition of the tree community. However, these structure differences are punctual and insufficient to determine specific communities.

Water erosion acts as the main form of soil degradation, promoting the release of particles that associated with factors such as climate, relief, soil vegetation and use and occupation favor this process. This study aimed to evaluate whether gullies are more likely to be present in a specific type of landform and how physical and chemical soil characteristics vary between the internal and external environments of concave and convex gullies. The study was performed in the Cachimbal River sub-basin, Pinheiral (RJ). Gullies were mapped and the quantitative and qualitative evaluations (occurrence in concave or convex surface). For each type of landform, one gully was selected. Soil samples (disturbed and undisturbed) were collected from the internal and external surfaces of each gully at a depth of 0-10 cm and soil chemical and physical characteristics were determined. More gullies were present in convex landforms and differences in soil characteristics were observed between the internal and external gully surfaces, but not between different landforms. Ca+2, S value, H+Al, T value, Mg+2, TOC and K+ were associated with the external surface, and P, Al+3, aluminum saturation, V%, and pH with the internal surface. Natural and total clay content, and soil and particle density were the physical characteristics associated with the external surface, and total and fine sand content, porosity, degree of flocculation, and silt content with the internal surface.