What do we know about treelines of the Anthropocene in High Asia?

Abstract

The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment. The Qinghai-Tibet Plateau (QTP), which has both forest drought-lines and alpine treelines with specific ecotone structures, including isolated trees in treeless plant-covers that represent ever existed forest cover according to 'Lonely Tooth Hypothesis', offers an excellent model in which to examine the extent and timing of human activity on the conversion of forest to pasture. The objectives of this paper are to review (1) palaeo-environmental records of the Early Holocene that indicate when forests were first converted to 'alpine meadows', and (2) current records of the changing treeline ecotone in the region. 'Alpine meadows' of the QTP are part of the largest conversion of mountain forests into pastures worldwide. This change in forest cover is possibly a consequence of the agro-pastoral transition and the dawn of the Anthropocene on the QTP. To date, however, there is an interdisciplinary gap in knowledge of 5000 years between the palaeo-ecological and the archaeolocical and zoo-archaeological records. Rapid changes of the rural economy and the exodus from remote highland villages to down-country cities have diminished the age-old impacts of summer grazing and pasture management by fire; reforestation is obvious, but often seen exclusively as an effect of Anthropocene global warming. We believe that more interdisciplinary collaborations on the QTP are necessary to increase our understanding of the treelines of the Anthropocene in High Asia.