Holocene Grassland Fire Dynamics and Forcing Factors in Continental Interior of China

• Published in: Geophysical research letters Vol. 47; no. 13
• Main Authors: Li, Jianyong, Wang, Ninglian
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.07.2020
• Subjects: Biofuels; Burning; charcoal; Climate; Climate change; Climate effects; Climatic conditions; Dynamics; fire regime; Fires; Flammability; Fuels; Global warming; Grasslands; Holocene; Moisture; Moisture availability; Natural resources; NW China; Records; Seasons; Socioeconomic factors; Spring; Spring (season); Vegetation; China
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2020GL088049

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. Plain Language Summary Recently, catastrophic fires occurred frequently, such as California (2018), Amazon (2019), and Australia (2020), causing tremendous losses to natural resources, human/animal lives, and socioeconomic assets. The fire risks with considerable costs are projected to increase under global warming. To estimate the effects of forthcoming climatic fluctuations on fire activity for large‐scale fire‐prone ecosystems, we need sufficient long‐term information regarding the fire‐fuel‐climate interactions on various spatial‐temporal scales. Notably, widespread grasslands make up roughly 40.5% and 41.7% of the Earth's and China's land surface, respectively. However, Holocene fire dynamics across extensive grassland areas of NW China are not well understood, owing to the scarcity of paleofire records. Here, we provide Holocene sedimentary records of grassland fire and vegetation in Xinjiang of NW China to explore the linkages among fire, fuel, and climate during the Holocene. We suggest that climatic conditions of spring fire‐season and moisture availability are essential for driving the fire‐regime evolution. We find that intensified fire activity has been caused by increased flammability (fire‐season) and enhanced cumulative biomass (fuel‐load) along with increased humidity throughout the Holocene. More importantly, we critically need more grassland paleofire records to understand long‐perspective fire dynamics of interior China. Key Points The study examines Holocene fire and vegetation records to explore fire‐fuel‐climate interactions in Bortala Basin of Xinjiang in NW China Grassland fire regime is fuel‐limited and burning shows a gradually increasing trend over the last ca. 10,000 years Relative humidity and temperature of the spring fire season are the primary drivers of fire‐regime dynamics during the Holocene