Successful Biological Methods for Combating Desertification at Degraded Areas of China - Combating Desertification in Asia, Africa and the Middle East - page 56

Fig. 3.3 Shrubs that have a high resistance to wind erosion are planted on the front or middle part
of the windward slopes of dunes and trees such as Populus can be planted on the downwind side
species with different growth forms demonstrate different biological features and
different effectiveness to fix sand. The right choice of proper arrangement should
be done in light of the specific local site condition when establishing sand breaks,
so that all species of the plantation can bring about their desired effect. No single
species can play a good role in sand fixing by itself but may be good in combination
with others. Other practical considerations go against mono-specific plantations e.g.
susceptibility to disease and insects.
Annual and biennial plants are short-lived and only play a limited role in the
sand-fixing process. Perennial herbs grow well in the wet years. They have shallow
root systems and can obtain moisture at the upper layer of the sand land. So when
trees or shrubs are planted, a certain number of perennial herbs should be inter-
planted in the same site. By doing so, the competition of moisture and organic
matter in the sandy lands can be minimized and vegetation coverage increased.
Consequently, the sand-fixing process can be accelerated.