摘要
在中国东北样带沿线的内蒙古草原地区采集了一些常见植物的叶片样品,并测定其δ^(13)C和δ^(15)N值,分析了其统计学特征以及对环境因子(年平均降雨量和温度)的响应模式。发现东北样带草原区同时存在C_3和C_4两种不同光合途径的植物,但是C_3植物占主导地位,C_4植物数量有限。C_3植物叶片δ^(13)C随着年平均降雨量和年平均温度的升高而显著降低,反映了此区域C_3植物δ^(13)C受控于降水量和温度。C_4植物的叶片δ^(13)C值随着降雨量的增多而有轻微升高的趋势,但是C_4植物的叶片δ^(13)C值对年平均温度的响应不敏感。不论对C_3植物还是C_4植物而言,叶片δ^(15)N都随降雨量增加而显著降低,即干旱区的植物叶片δ^(15)N大于湿润地区,这说明降水是影响植物叶片δ^(15)N的一个重要因素。然而两者叶片δ^(15)N对温度的响应不敏感。
The determination of plant carbon （ C ） isotopic concentration is related to the C assimilation and diffusion of COs influenced by water stress. In addition, the determination of plant nitrogen （N） isotopic concentration is related to the availability of nutrients and water, and is indicative of N cycling on different spatial and temporal scales. The question arises as to whether a relationship exists in the processing of C and N by vegetation across various physical environments in temperate steppes as evidenced by the natural abundances of C and N in foliage （δ13C and δ15N ）. Given the strong precipitation and temperature variation, Inner Mongolia is an ideal region for this study. The regional patterns of foliar δ13C and 815N along the Northeast China Transect （NECT） in Inner Mongolia steppe, and their relationship with environmental factors, which are mean annual precipitation （MAP） and mean annual temperature （MAT）, have been studied. We collected 158 samples, which included 18 species of C3 plants and 5 species of C4 plants. The δ13C values of C3 plants in this region range from -28.87‰ to -22.53‰, while those in C4 vary from -14.06‰ to -11.64‰. The δ15N values of plants in this region range from -2.63‰ to 8.57‰ with a mean value of 2.13‰, and most values （80% of all data） are higher than 0%0. Our results show that δ13C values in C3 plants decrease significantly with increasing MAP （R2 = 0.549, P〈 0.001 ） , such that the coefficient of δ13C-MAP is -1.16‰/100 mm. However, a positive linear relationship exists between the 813C values of C4 plants and MAP （R2= 0.188, P〈0.05）. Foliar δ13C values of C3 plants also decrease significantlywith increasing MAT （R2= 0.549, P〈0.05）, such that the coefficient of δ13C-MAT is -0.14‰/1℃. However, MAT does not significantly affect the δI3C values of C4 plants （R2 = 0.032, P = 0.432）. The δ15 N values decrease significantly with increasing MAP, both for C3 plants （R2=0.373, P〈0.001） and C4
出处
《生态学报》
CAS
CSCD
北大核心
2016年第1期235-243,共9页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(40871032)
中国科学院知识创新工程重要方向项目(KZCX2-EW-QN604)
关键词
稳定性碳同位素
稳定性氮同位素
温带草原
样带
N循环
水分利用效率
carbon isotope ratios
nitrogen cycle
nitrogen isotope ratios
temperate steppe
transect
water use efficiency
