Application and limitations of the Artemisia/Chenopodiaceae pollen ratio in arid and semi-arid China

• Published in: Holocene (Sevenoaks) Vol. 22; no. 12; pp. 1385 - 1392
• Main Authors: Zhao, Yan, Liu, Hongyan, Li, Furong, Huang, Xiaozhong, Sun, Jinghui, Zhao, Wenwei, Herzschuh, Ulrike, Tang, Yu
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.12.2012; Sage Publications Ltd
• Subjects: Arid zones; Artemisia; Chenopodiaceae; Moisture content; Paleoecology; Pollen; Vegetation; China; China, People's Rep; A/C ratio; dryland; climate variables; vegetation types
• ISSN: 0959-6836; 1477-0911
• DOI: 10.1177/0959683612449762

The Artemisia/Chenopodiaceae (A/C) ratio is assumed to be a useful index for reconstructing moisture changes in arid and semi-arid regions. Thorough modern pollen studies are still lacking to understand the reliability and limitation of A/C ratio as a moisture indicator, however. Here we review how well this ratio can be applied in arid and semi-arid China on the basis of new surface pollen data, previous data synthesis and other publications. Results indicate that variance in the A/C ratio can permit identification of modern vegetation types and that the A/C ratio generally has a positive relationship with annual precipitation. However, soil salinity, vegetation community composition, human activity and sample provenance (e.g. soil and lake sediments) will affect the values of the A/C ratio in different vegetation zones and therefore the A/C ratio is not comparable in different regions. We argue that the A/C ratio can only be used to reconstruct vegetation types and climate change in regions with precipitation <450–500 mm, and in steppe, steppe desert and desert areas. Careful studies should be undertaken to understand the modern pollen–vegetation–climate relationships in various regions before using the A/C ratio to interpret vegetation and climate.