Potential of soil phytoliths, organic matter and carbon isotopes for small-scale differentiation of tropical rainforest vegetation: A pilot study from the campos nativos of the Atlantic Forest in Espirito Santo State (Brazil)

摘要

A truthful vegetation reconstruction is essential for understanding the historical trajectory of climate change and as well as the nature and extent of human impact on ecosystems. A classical approach to these studies is the use of pollen to identify flora composition and variability over time. However, the use of pollen is not always viable due to lack of depositional environments and general taphonomic processes, such as edaphic conditions. The most durable plant fossils, with widespread presence in diverse depositional realities, are phytoltihs. These proxies are common, well preserved in soils and with great potential for the detection of vegetation signals at micro and meso-level. Therefore, phytoliths are an important tool for recognising variability in major biomes such as tropical forests. In this study we illustrate the results of a pilot project in the Atlantic Forest (Mata Atlantica) of Brazil. The Atlantic Forest is a very diverse ecosystem and its environmental history is still poorly known, especially in relation to the origin and development of non-forested islands (campos nativos) within the forest. Campos nativos create a mosaic with the Mata Atrantica and their current persistence is due to a combination of topographic effects, hydrology and soil. Our work evaluated the potential of soil phytolith, total organic content (TOC) and delta C-13 of two grassland/savannah campos nativos in the Vale Nature Reserve in Linhares (state of Espirito Santo). The results from isotopic analysis show the relevance of C3 plants since the beginning, and for all the sedimentary history, in both campos nativos. The soils of the nativos are spodosols and, surprisingly, the phytolith composition has been drastically affected by the edaphic conditions. The phytolith assemblages are often impoverished, especially in the soil sandy layer. However, the assemblages still show an important local floristic component (micro scale) with an input from the surrounding vegetation (meso-scale). (C) 2016 Published by Elsevier Ltd.