Reconstructing the distribution of the paleobiome types in the Three-River Headwaters Region in China from the middle Holocene

This study examined the spatial and temporal patterns of the paleobiome types in the Three-River Headwaters Region (TRHR, Sanjiangyuan) in China from the middle Holocene (i.e. 6000 BP). Existing studies explored the patterns of paleobiome types by identifying the type of biomes in pollen sites, based on the taxonomical assemblage of pollen samples. This site-wise identification, however, is not suited for the analysis of the TRHR because pollen sites in the region-level are discrete and low-resolution. In this study – to solve the lack of the pollen sites – climate data, which are easy to interpolate, were extracted from the pollen data by pollen transfer functions. Next, the extracted climate data were calibrated and interpolated over the TRHR and study period. Then, a physiological biome model based on climate was used to produce the chronology of the distribution of the biome types. Consequently, the chronology was reconstructed with a time interval of 50 years and a spatial cell size of 0.5 ° × 0.5 °. From the results, the variations in the distribution of the paleobiome types were mainly dominated by 36 patterns over 10 biome types. In detail, tundra and semidesert were the main types, and the alternation of these two types was the main pattern. Further, the long-term evolution was from tundra to semi-desert, and the precipitation was the main driving force for changes in biomes, while temperature also had some influence.