C7 - Stability of rainforest margins in space and time: Holocene rainforest, climate, fire, human impact and land use dynamics in Sulawesi, Indonesia
For understanding the stability of rainforest margins and for future sustainable land use management an integrated study including changes on past vegetation, biodiversity, climate, fire, human impact and land use dynamics is needed. Special attention will be given to Holocene human impacts on vegetation, land use changes, history of rattan use, adaptation to environmental changes, and ENSO droughts frequency that have caused fires with strong effects on nature and society. Results will contribute to predict future changes in rainforest margins and to facilitate conservative action in the perspective of sustainability.
For understanding the stability of rainforest margins and for future sustainable land use management an integrated study which comprises changes in past vegetation, biodiversity, climate, fire, human impact and land use dynamics is needed. In the framework of STORMA we will analyse the Holocene vegetation and biodiversity, the history of fire and the climate variability in Central Sulawesi during the Holocene. The investigaton will focus on the stability of rainforests and dynamics of plant diversity in the past. In this context the diversity of palm trees (Calamoidae in particular) is of special concern.
Attention will be given to the frequency and intensity of ENSO droughts which cause fires with strong effects on nature and society in Indonesia. In addition the duration of intervals between the recurrent El Niño events during the Holocene will be observed. If we can detect traces of similar devastations as occurred during the 1997/98 ENSO event in earlier times, these will provide data about the history of climate and vegetation in an overall perspective.
Nowadays the heavy fires which occur during ENSO droughts in Indonesia are mainly human-induced. Often these fires were caused by slash-and-burn cultivation, when fires got out of control. The connection of the fires during ENSO events to human impact is obvious. This raises the question of human influence on vegetation in prehistoric and historical times. For this reason human impact on vegetation and biodiversity since the beginning of agricultural activity on Sulawesi at about 6000 years ago will be studied as well. Human impact includes changes in land use techniques, e.g. slash-and-burn agriculture, shifting cultivation, gradation of forest use intensities concerning logging and the use of non-wood-forest-products such as rattan, the introduction of agroforestry and crop plantation and, last but not least, deforestation. Regarding the long timescale of the Holocene, our project will be able to compare the early Holocene period with no or low human activity, the mid Holocene period with possible little or moderate activity and the late Holocene with strong human activities. Furthermore we will investigate different catchment areas characterised by either little (Lake Kalimpua) and strong human impact (Lake Lindu).
Methodically, our approach is linked to innovative temporal high resolution pollen, spores, charcoal, stratigraphical and geochemical analysis on sediment cores primarily collected from three different lake and peat deposits. The cores will be radiocarbon dated and studied with XRF-scanners on a high resolution scale (mm) or if necessary a super high resolution scale (μm). Especially the combination of different environmental proxies (pollen, spores, charcoal and sediments) will allow us to identify and to reconstruct past environmental changes in detail. This multiproxy analysis will serve as a powerful tool to interpret past environmental changes so as to understand modern and predict future environmental changes in rainforest margins. The results will contribute to conservative action in the perspective of sustainability.