Successful Biological Methods for Combating Desertification at Degraded Areas of China - Combating Desertification in Asia, Africa and the Middle East - page 54

4 Successful Biological Techniques for Protecting

Different Sites

Biological methods are the ultimate way for drift sand stabilization and a fundamen-
tal approach to the development and proper utilization of sandy land (Yaolin and Jihe
2005 ). The measures used to fix sands in China can be classified into two types: One
is to protect the existing vegetation on the sand or to plant trees, shrubs and grasses
where such vegetation has deteriorated or is absent. Biological methods may or may
not be used in conjunction with mechanical measures (Chap. 2 ) . Different methods
would be suitable for the various conditions and also for different purposes e.g.
protection of infrastructure.

4.1 General Biological Characteristics of Plant Species

Artificial plantations of trees, shrubs and grass are the most effective measures
to stabilize mobile dunes and fix shifting sands in arid, semi-arid regions for
protecting village and agricultural properties. The methods used in plantation for
fixing sands are:

- Plantations of trees, shrubs and grasses in the inter-dune and low-lying lands

(Fig. 3.2 ) Shrubs that have a high resistance to wind erosion are planted on the
front or middle part of the windward slopes of dunes (Fig. 3.3 )

- Cuttings of species that are drought-resistant in sandy soil, such Salix spp.,

Artemisia spp., Calligonum spp. are planted in the leeward slopes of sand dunes
to fix the sand surface of dunes. This plantation is characterized by non-irrigation,
quick growth with production of fodder for livestock and fuel wood (Yang et al.
2005 ).

- Cuttings of species that are drought-resistant in sandy soil, such Salix spp.,

Artemisia spp., Calligonum spp. are planted in the leeward slopes of sand dunes
to fix the sand surface of dunes. This plantation is characterized by non-irrigation,
quick growth with production of fodder for livestock and fuel wood (Yang et al.
2005 ).

4.1.1 Selection of Sand Binder Species

The region is characterized by a dry climate, strong wind-drift sands, and acute
changes in temperature, aridity and infertility of soil. Since 1956, scores of species
of trees, shrubs and semi-shrubs have been experimentally introduced and planted
on barchan dunes at several sites. The species include: Pinus tabuleaformis, Pinus
sylvestris var. mongolica, Ulmus pumil and Robinia pseudoacacia . These species
withered, but some of Populus simmonii, Populus nigra var. thevestina have
been tested and survived on the leeward slope. But they, even the native species