Organic matter composition and paleoclimatic changes in tropical mountain peatlands currently under grasslands and forest clusters

摘要

Tropical peatlands are important ecosystems for Planet Earth, as they store large amounts of carbon and water. A better understanding of the impact of vegetation type and altitude in content, composition, and rate of accumulation of organic matter is key for assessing the current role of such environments. This study evaluated fibric and soluble fractions as well as the lignocellulosic and the isotopic compositions of the peat organic matter from four tropical mountain peatlands located at different altitudes of the Serra do Espinhaco Meridional, state of Minas Gerais, Brazil. The peatlands are currently under grasslands and forest clusters. Samples of peat under both vegetation types were collected and analyzed for organic matter fractions, cellulose, and lignin (van Soest method), as well as carbon and nitrogen isotopes. Different depths were chosen for radiocarbon dating of selected samples. The organic matter of peatlands currently under grasslands and forest clusters presented differences in soluble fractions, lignocellulosic composition, and delta C-53 values. Multivariate analyses allowed grouping the peatlands by altitude and vegetation type, The chronological succession of grassland and forest clusters in tropical mountain peatlands was influenced by altitude and was related to paleoclimatic changes.