Chinese Bulletin of Botany ›› 2011, Vol. 46 ›› Issue (6): 675-687.DOI: 10.3724/SP.J.1259.2011.00675

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Carbon Isotope Composition of C3 Herbaceous Plants and Its Relation to Humidity Index in Arid and Humid Climate Zones in Northern China

Xianzhao Liu1,2,3*, Chaokui Li1, Shujian Xu3*, Wenwen Wang2, Guoan Wang4, Lili Zhao2   

  1. 1College of Architecture and Urban Planning, Hunan University of Science and Technology, Xiangtan 411201, China

    2College of Geography and Planning, Ludong University, Yantai 264025, China

    3Department of Geography, University of Linyi, Linyi 264000, China

    4College of Resources and Environmental Sciences, China Agricultural University, Beijing 100083, China
  • Received:2011-01-26 Revised:2011-04-28 Online:2011-11-01 Published:2011-11-18
  • Contact: Xianzhao Liu,Shujian Xu

Abstract: Data for geographic location, climatic conditions, and carbon isotope values of 325 C3 herbaceous plant samples 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 species 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 revealed 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 contrast, 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.