Serapilheira e aporte de nutrientes em cronossequência de áreas em restauração ecológica

Abstract

The restoration process of degraded areas must be monitored over the years by means of indicators, among which are litter production and nutrient cycling, to ensure the occurrence of successional advancement. Therefore, the objective of this work was to evaluate the efficiency of ecological restoration over a chronosequence in areas under the Atlantic Forest domain, through the litter contribution and nutrient content and its relationship with environmental variables. The study was carried out in the Private Natural Heritage Reserve - RPPN Fazenda Bulcão, located in the municipality of Aimorés, Minas Gerais. Four areas of the property were considered, three in different periods of the restoration process (Area 1: 20-years; Area 2: 10-years and Area 3: 5-years) and a reference area. To evaluate the biomass and nutrient content, litter input was collected in 10 suspended collectors in each area, monthly, between April 2017 and January 2019, and separated into fractions F1: leaves; and F2: in wood and miscellaneous (W+M), subsequently dried and weighed. For the chemical analysis of macronutrients and organic carbon of this litter, the monthly samples of each fraction were grouped into two seasons: summer (October to March) and winter (April to September). To assess the effects of time on litter input, generalized linear models (GLM) were used and the litter content was evaluated using non-metric multidimensional scaling (NMDS). The relationship between the total content of each litter nutrient, edaphic variables and leaf area index (LAI) was evaluated by multiple regression analyzes using generalized linear models (GLM). The total annual litterfall production was 10,503.38 kg ha-1 yr-1 for the 5- year-old area under restoration, 5,806.49 kg ha-1 yr-1 for the 10-year-old area, 22,710.76 ha-1 year-1 in the 20-year area and 24,879.73 kg ha-1 year-1 reference, for the first year of evaluation. Considering the production of seasonal litter and the content of nutrients and organic carbon, an increase was observed along the chronosequence under study, bringing the area of 20 years closer to the reference area and differing from younger areas (5 and 10 years). The variables that best explained the behavior of the litter content of nutrients were pH, cation exchange capacity (T), soil moisture and LAI. The results presented in this study indicated an advance in the ecological restoration process over the years in areas of the Atlantic Forest, based on the analysis of litterfall. However, it is suggested that complementary studies of species composition and litter dynamics be carried out in order to have a more comprehensive monitoring of the areas and their processes.