Unravelling the past 1,000 years of history of human–climate–landscape interactions at the Lindu plain, Sulawesi, Indonesia

Abstract

The Lindu plain, located in the northern mountainous region of the Lore Lindu National Park in Sulawesi, Indonesia, provides many ecosystem services for the population inhabiting the area and harbours a unique biodiversity. Palynological, charcoal and diatom analyses of a lake sediment core from Lake Lindu (Danau Lindu) reveal that during the last 1,000 years the Lindu plain has been modified by human activities. Evidence of frequent burning and possible shifting cultivation from an earlier phase from ca. ad 1000 to 1200 might be related to the metal age population which erected the megaliths in the province of Central Sulawesi. From ca. ad 1200–1700 there followed 500 years of wetter climate conditions, corresponding to the southward movement of the Intertropical Convergence Zone. At the same time, decreases of macro-charcoal concentrations and pioneer vegetation indicators show that the use of the landscape of Lindu plain had become more permanent. Following a phase of forest recovery from ca. ad 1730 to 1910, the most recent part of the Lake Lindu record shows a trend towards deforestation that started in the late 20th century, lasting until now. The lake level started to fall at the beginning of the 20th century, as shown by the increase of sedimentation rate and supported by low pollen concentration and palaeomagnetic data. Such a change was unprecedented for the last 1,000 years covered by the record, and it has no link to the climate variability as reconstructed for the last hundred years. If deforestation increases and a larger amount of water is channelled away from the lake for irrigation purposes, the lake level will continue to fall. This suggests that there is a need for better management of the forests surrounding the plain and of the irrigation systems in the area open for cultivation.