Holocene vegetation changes in the transition zone between subtropical and temperate ecosystems in Eastern Central China

Abstract

The Qinling Mountain Range represents the current transition zone between the temperate and subtropical ecosystems of Eastern Central China. Climate changes have certainly affected the vegetation composition to the north and south of this mountain range in different ways. Here, we reconstruct past regional land-cover changes by applying the REVEALS model to pollen records from the temperate, temperate–subtropical transition, and subtropical vegetation zones (Tianchi Lake, Daye Lake, and the Dajiuhu wetland, respectively). The location of sites in the mountains can complicate the interpretation of pollen results owing to the complexity of the landscape. Herein, we have therefore tested the effect of using different model inputs for land-cover reconstructions. Based on the best options, we found that regional vegetation changes were mainly controlled by the general climate trend. Both temperate and subtropical trees developed when the climate conditions were warm and moist during the mid-Holocene. The later period is characterised by cooler and drier climate conditions that result in an increase in open land, specifically from 2200 calendar years before present (cal yr BP). This landscape openness tendency has been amplified by the spread and intensification of land use (e.g., deforestation to develop farming) over the last few millennia and centuries. The vegetation at the current transition between the temperate and subtropical ecosystems of Eastern Central China has been mainly influenced by, and is still dependent on the climate; however, the impact of land use on vegetation seems to have been greater and more intense earlier in the temperate zone than in the subtropical zone.