Grass habitat analysis and phytolith-based quantitative reconstruction of Asian monsoon climate change in the sand-loess transitional zone, northern China

摘要

We investigated climate niches of grasses at regional scales and quantitatively reconstruct Asian monsoon precipitation at the sand-loess transitional zone in northern China. Our results provide direct evidence that certain grass lineages have been specialized in specific habitats: Pooideae grasses stand out and occupy a much cooler environment than all other subfamilies; Pooideae, Aristidoideae, and Chloridoieae occupy dry environments. Pooideae grasses occupy the coldest and driest environments compared to all other subfamilies, with a mean annual temperature (MAT) and precipitation (MAP) of similar to 13.6 to similar to 15.3 degrees C and 224 to similar to 1674 mm, respectively, at a regional scale. We built a database for grasses and their corresponding climate parameters. Based on this database, past climate parameters at the margin of the Asian summer monsoon since similar to 70 ka were quantitatively reconstructed by phytolith assemblages. They show that this area was dominated by cold- and dry-adapted grasses since similar to 70 ka with a MAT and MAP of similar to 3.3 to similar to 11.0 degrees C and similar to 442 to similar to 900 mm, respectively, generally consistent with the results of phytolith-based transfer function reconstructions and with the results of previous nearby pollen-based quantitative reconstructions. With the improvement of the species-climate and ecosystem dataset, our database-based method is a promising quantitative reconstruction approach to past climatic change in the monsoon region.