The annual average temperature in northern China

Abstract: Four common C3 plant species-Chenpodium album, Lepidium apetalum, Cirsium leo and Plantago depressa-were sampled and their δ13C values ??were measured. The δ13C values ??of all the four plant species decrease with increasing annual average temperature, and the responses of the carbon isotopic compositions of Chenpodium album and Lepidium apetalum to temperature change are much more intense than those of Cirsium leo and Plantago depressa. Highly significant linear relationships between carbon isotopic compositions of Chenpodium album, Lepidium apetalum and Cirsium leo, but Plantago depressa, with annual temperature are observed. These results suggest that the δ13C values ??of Chenpodium album, Lepidium apetalum and Cirsium leo, but Plantago depressa, can be used as annual temperature proxies, and that Chenpodium album and Lepidium apetalum may be more suitable than Cirsium leo.