Nutrient cycling aspects as possible ecosystem functional indicators of successional stage in Semideciduous seasonal forest, Rio de Janeiro state, Brazil

Semideciduous Seasonal Forest is a phytophysiognomy of Atlantic Forest with high plant richness but low representativeness in few remnants areas in different successional stages. The assessment of the degree of conservation of those areas helps to indicate whether there is a need for taking strategies to favor forest succession. Thus, the aim of this study was to identify litterfall and its nutrient content, accumulated litter biomass on topsoil, leaf litter decomposition, and topsoil (0-10 cm) chemical attributes as possible indicators of successional stages in areas of Seasonally Semideciduous Forest. We collected available information in literature on CAPES Portal and Google Scholar (May/2021 to February/2022) for Pinheiral municipality, State of Rio de Janeiro, Brazil, which were evaluated by multivariate analysis. Accumulated litter biomass, nutrient content (N, P, K) in total litterfall, pH and P availability in topsoil, leaf litter decomposition constant, and half-life time of leaf litter were the most sensitive attributes to indicate the successional stage in the study area, according to Principal Component Analysis. This multivariate analysis indicated that areas in early successional stage were associated with higher values of leaves contribution, half-life of leaf litterfall, contents of Ca and K in total litterfall, whereas areas in middle successional stage were associated with higher values of pH, total organic carbon, exchangeable Ca2+, K+, and Mg+, sum of bases and cation exchange capacity, and lower values of extractable acidity and exchangeable Al3+ in the topsoil. Areas in advanced stages of succession were associated to higher values of total litterfall and its nutrient content (N, K, Mg), accumulated litter biomass, available P in topsoil, and leaf litter decomposition constant. The Cluster multivariate analysis revealed that the areas in advanced successional stage presented high dissimilarity in relation to the areas in early and middle successional stage.