中国西北C-3植物的碳同位素组成与年降雨量关系初探

本文对不同年降雨量环境下生长的藜、独行菜、魁蓟和平车前这4种常见C-3植物的δ¹³C进行了分析,发现这4种C-3植物的δ¹³C组成都表现出随年降雨量减少而变重的趋势,其中藜和独行菜的碳同位素组成对降水变化的响应相对要较其它2种植物强烈得多。藜、独行菜和魁蓟的δ¹³C组成与年降雨量有显著的线性关系,平车前碳同位素组成与年降雨量没有显著的相关性,表明藜、独行菜和魁蓟的δ¹³C组成可作为年降雨量的替代性指标,平车前的δ¹³C组成不能作为年降水的替代性指标。

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There is a tendency for precipitation in China that annual precipitation amount gradually decreases from the southeast to the northwest,and there is a obvious precipitation gradient zone in the middle latitude area in east Asia.Four C-3 plant species —Chenpodium album,Lepidium apetalum,Cirsium leo and Plantago depressa along the gradient zone were sampled,and their δ¹³C values were measured.δ¹³C values of all four plant species decrease with increasing the mean annual precipitation,and the responses of carbon isotopic compositions of Chenpodium album and Lepidium apetalum to precipitation change are much more intensive than that of Cirsium leo and Plantago depressa.Highly significant relations between carbon isotopic compositions of Chenpodium album,Lepidium apetalum and Cirsium leo,but Plantago depressa,and the mean annual precipitation are observed.These results suggest that δ¹³C values of Chenpodium album,Lepidium apetalum and Cirsium leo,but Plantago depressa,can be used as annual precipitation proxies,and that Chenpodium album,Lepidium apetalum may be more suitable than Cirsium leo.