1. Johnson J.-D., Tognetti R. and Paris P., Water relations and gas exchange in poplar and willow under water stress and elevated atmospheric CO2, Physiol. Plant., 2002, 1: 93–100
2. Zhai H.-B., Li J.-Y. and Huang W.-D., Water characteristics and gas exchange of Pinus tabulaeformis and Quercus variabilis mixed stand, J. Beijing For. Univ., 2004, 1: 30–34 (in Chinese)
3. Li J.-Y. and Terence J.-B., Effects of repeated cycles of rehydration on gas exchange and water use efficiency of seedlings, J. Beijing For. Univ., 1999, 3: 1–8 (in Chinese)
4. Huang Z.-B. and Shan L., A study on WUE and Pn diurnal change features and its mechanism in crops under different water conditions, Acta Agric. Boreal-Sin., 1999, 1: 47–52 (in Chinese)
5. He K.-N., Tian Y. and Zhang G.-C., The suitable soil moisture condition for forest growth in catchment afforestation in semi-arid region on Loess Plateau, Scientia Silvae Sin., 2003, 1: 10–16 (in Chinese)