4Cowan I R. Regulation of water use in relation to carbon gain in higher plants. In: Lange O L, Nobel P S, Osmond C B, et al. Physiological plant ecology Ⅱ. Water relations and carbon assimilation. Springer, Berlin Heidelberg New York, 1982, 589 - 613
5Larcher W. Physiological plant ecology: ecophysiology and stress physiology of functional groups. Springer: Berlin Heidelberg New York, 1995
6Scheidegger Y, Saurer M, Bahn M, Siegwolf R. Linking stable oxygen and carbon isotopes with stomatal conductance and photosynthetic capacity: a conceptual model. Oecologia, 2000, 125:350 - 357
7Kumar N, Kumar S, Ahuja P S. Photosynthetic characteristics of Hordeum, Triticum, Rumex, and Trifolium species at contrasting altitudes. Photosynthetica, 2005,43(2) : 195 - 201
8Farquhar G D, Hubick K T, Condon A G. Carbon isotope fractionation and plant water-use efficiency. In: Rundel P W, Ehleringer J R, Nagy K A. Stable Isotope in Ecological Research. New York: Springer- Verlag, 1989, 21-40
9Robinson David.δ^15 N as an integrator of the nitrogen cycle. Trends Ecol Evol, 2001, 16:153-162
10Smedley M P, Dawson T E, Comstock, et al. Seasonal carbon isotope discrimination in a grassland community. Oecologia, 1991, 85:314 - 320