Pollen analysis and paleoecology from the Bortala River National Wetland Park, located in the Wenquan County, Xinjiang Province, Northwest China

Grasslands cover 41.7% of China's land surface and distribute mainly in NW China. To project future change of grassland fires, it is essential to explore paleofire dynamics. However, comparatively little is known about the patterns and driving forces of grassland fires in NW China due to the scarcity of paleorecords. Here, we present Holocene sedimentary records of grassland fire and vegetation in westerly-dominated Xinjiang (NW China) to examine fire-fuel-climate interactions. We find that grassland fire-regime is fuel-limited, consistent with other grasslands worldwide. We reveal that burning increased throughout the Holocene, due to increasing moisture, grass cover, fuel load and temperature of spring fire season. The Holocene pattern of burning coincides with several other records nearby and a global-scale grassland fire record. Our results are different from monsoonal China where fuel load is not a constraining factor and more (less) fires occurred during colder/drier (warmer/moister) periods in the Holocene.