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tion coverage, the alfalfa plantation gained the significant advantage in ecological
vegetation restoration compare to vegetation restoration in abandoned land and
sweet clover plantation land.
5 Sustainability of Dryland Agriculture Ecosystem
To control soil erosion, accumulate rainwater and improve water use efficiency via
large-scale land leveling is the fundamental of rapid development of dryland agri-
culture over the last 20 years in China (Li et al. 1999a, 2003 ; Li and Xu 2002 ). Land
leveling and rainwater accumulation programs have been basically accomplished
through the establishment of various terraces across different periods of past few
decades. In addition to ridge-furrow plastic-mulching system used for improving
water use efficiency as mentioned above, another key technology is the construction
of underground rainwater storage cellar, with the aim to provide the necessary sup-
plementary irrigation water for the plants with high economic value. The rainwater-
harvesting cellar can provide a variety of combinations with water, fertilization, and
soil thermal supply, which offered the conditions for the introduction of high-value
economic plants. Greater diurnal temperature difference and better lighting resource
were conducive to the accumulation of photosynthetic products in semi-arid areas.
This help creates the most favorable conditions to increase crop quality and yield.
Therefore, with the development of high-value economic plants, the economic effi-
ciency of agricultural production process was increased. The new dryland agricul-
ture system was expected to alter the hopeless situation of traditional dryland
agriculture, and to become a promising agriculture development system. The efforts
have injected new power into the entire agriculture and rural development (Cui and
Wang 2002 ; Wang et al. 2001 ; Cui et al. 2005 ).
Livestock industry in the semi-arid region is endowed with a certain advantage.
A large number of studies suggested that this advantage should play more important
roles (Ren 2007 ; Ren and Lin 2009 ; Shan and Xu 2009 ; Zhang 2010 ). However, as
the population is increasing with time, the contradiction between food production
and livestock production has become increasingly prominent. For the past 20 years,
under the support of rain-harvesting farming techniques, grain yields per unit area
were substantially increased, and the area of farmland used for self-consumption
crops was gradually reduced. Moreover, due to the introduction and cultivation of
cash crops, economic benefits have been improved, which has provided a more flex-
ible preconditions to return farmland to grassland for feeding livestock, adjust and
optimize industrial structure. Furthermore, farmers could optimize the production
structure interactively with the market (Li and Xu 2002 ; Li et al. 2003 ).
Based on the previous analysis, combined with characteristics of the hilly land-
scape in dryland agriculture region, we proposed a management model of dryland
agricultural landscape system (Fig. 7 ). The resource conditions gradients tended to
be worse from the foot to the top of low hill. This can also be seen as an ecological
band spectrum (Li et al. 2003 ).
F.-M. Li et al.