Roques K G, O’Connor T G, Watkinson A R. Dynamics of shrub encroachment in an African Savanna: relative influences of fire, herbivory, rainfall and density dependence. Journal of Applied Ecology, 2001, 38(2): 268-280.
[6]
Whitford W G. The Ecology of Desert Ecosystems. New York: Academic Press, 2002.
[7]
Robins J G, Hansen J L, Viands D R, et al. Genetic mapping of persistence in tetraploid alfalfa. Crop Science, 2008, 48: 1780-1786.
[8]
Fu S L, Zou X M, Coleman D. High lights and perspectives of soil biology and ecology research in China. Soil Biology and Biochemistry, 2009, 41(5): 868-876.
Okin G S, Gillette D A, Herrick J E. Multi-scale controls on and consequences of aeolian processes in landscape change in arid and semi-arid environments. Journal of Arid Environment, 2006, 65: 253-275.
Belanger G, Richards E J, McQueen R E. Effects of harvesting systems on yield, persistence, and nutritive value of alfalfa. Canadian Journal of Plant Science, 1992, 72: 793-799.
[14]
Grover H D, Musick H B. Shrubland encroachment in souththern New Mexico, U.S.A.: an analysis of desertification processes in the American southwest. Climate Change, 2000, 17: 305-330.
[15]
Su Y Z, Zhao H L. Soil properties and plant species in an age sequence of Caragana microphylla plantations in the Horqin Sandy Land, north China. Ecological Engineering, 2003, 20: 223-235.
[16]
Riday H, Brummer E C. Persistence and yield stability of intersubspecific alfalfa hybrids. Crop Science, 2006, 46: 1058-1063.
