【摘要】 通过对中国北方C3草本植物稳定性碳同位素的测定以及有关该区植被碳同位素资料的收集,共获取了47个样点的地理位置、气候因子和325个植物样品的碳同位素数据;计算了中国北方不同气候分区的湿润指数,分析了C3草本植物δ13C值的空间特征以及与湿润指数等环境因子之间的关系。在所调查的范围内,中国北方地区C3草本植物δ13C值的分布区间为-29.9‰--25.4‰,平均值为-27.3‰。C3草本植物δ13C的平均值从半湿润地区到半干旱地区再到干旱地区显著变重;3个气候分区植物δ13C值的变化范围分别是-29.9‰--26.7‰(半湿润区)、-28.4‰--25.6‰(半干旱区)和-28.0‰--25.4‰(干旱区)。一元回归分析表明,各气候分区C3草本植物δ13C值与湿润指数的关系存在差异,在半干旱区、半湿润区和整个北方地区,C3草本植物δ13C值与湿润指数均呈显著线性负相关(P<0.05),随着湿润指数的增加,C3植物δ13C平均值均变轻,但下降幅度不同。而在北方干旱气候区内,C3草本植物δ13C与湿润指数呈显著正相关(P<0.05),湿润指数每升高0.1,植物δ13C平均值增加1.3‰。年均温度可能是决定该区内各样点湿润指数和C3植物对13C分馏能力差别的主要原因。更多还原

【Abstract】 Data for geographic location,climatic conditions,and carbon isotope values of 325 C3 herbaceous plant sam-ples were obtained at 47 sampling sites through systematic investigation of a wide variety of natural habitats and δ13C data from the published literature of C3 herb species in northern China.We calculated the humidity indices for different climatic areas in northern China and compared the spatial characteristics of δ13C composition and carbon isotope values for C3 herbaceous plants with climatic environment factors(especially humidity index).The δ13C values for C3 plant spe-cies in northern China as a whole ranged from-29.9‰ to-25.4‰,with a mean of-27.3‰.From the sub-humid to semi-arid and arid areas,the mean δ13C values of C3 plants increased with decreasing mean annual precipitation.The variation in δ13C values differed among the 3 climatic areas in northern China,namely-29.9‰ to-26.7‰(sub-humid area),-28.4‰ to-25.6‰(semi-arid area) and-28.0‰ to-25.4‰(arid area).Single-element regression analysis re-vealed a difference in relationship between δ13C values of C3 herbaceous plants and humidity index among climatic areas.The δ13C values of sampling sites in semi-arid area,semi-humid area and the whole northern China all were negatively related to humidity index(P<0.05),and the mean δ13C values of plants decreased with increasing humidity index.In con-trast,δ13C values in the northern arid area was positively related with humidity index(P<0.05).A 0.1 increase in humidity index in the arid area would produce a 1.3‰ increase in δ13C,and annual mean temperature has an important role in differences in humidity index and isotope fractionation among sampling points in the arid area.更多还原