Fjölrit RALA - 05.12.1999, Blaðsíða 99

RALA Reportno. 200
Transformation of desertified land in the Grazing-farming
interlaced belt of Northern China
Liu Xinmin and Zhao Xyue-yong
/nstitute of Desert Research, Chinese Academy ofSciences, Lanzhou City, 730000 China
Tel: 0931-8839197/8847614: Fax: 0931-8883209/8889950: E-mail: cibidr@ns.tb.ac.cn
ABSTRACT
This rangeland-farmland interlaced belt with a fragile eco-system is mainly distributed along the
Great Wall and the Xiliaohe River, occupying an estimated area of 200,000 km2. Over-grazing and
over expansion of dry farming, in conjunction with highly erodible sandy soils and a harsh windy and
dry climate, have combined to cause extensive vegetation degradation and soil erosion. Since about
200 B.C., rain-fed agriculture has crept several times into dry areas and cropping has now taken place
even in some regions of this belt receiving as little as 150 mm of mean annual precipitation, which is
important historical reason for the fragility of the whole belt. The core of the fragility is thought to be
the imbalance between the anthropogenic pressure and the limited renewable resource supporting ca-
pacity. Inappropriate strategies of desertification control have also delayed the transformation process
of desertified land and resulted in large areas of dwarf trees, less palatable range vegetation and se-
verely eroded farmland.
Heavy population pressure prevents light grazing levels and the restoration of the zonal steppe
vegetation. By traditional plantation methods only, the theoretic approach to the eco-balance between
anthropogenic pressure and resource capacity has to be to create a new pattem of pasture-agriculture
combination with higher production and sustainable land use. In the regions with densely distributed
sand dunes, an eco-model named “small biosphere” can increase the production in the inter-dune de-
pressions so as to initiate the vegetation restoration on the surrounding sand dunes. Inserting the tech-
nique of water-saving rice cultivation which was plastic film for water seepage prevention in the core
zone of the “small biosphere” has further perfected the eco-model. In the regions with larger area of
rain-fed cropland intruded in the rangeland area, readjustment of land use structure is needed, by
which a small part of the rain-fed cropland can be transformed into irrigated cropland. The rest of the
land must then be reversed to rangeland in order to control soil erosion. In the regions with gently
sloping sandy rangeland the combination of grazing controlling measures with establishment of shel-
terbelt networks can promote the vegetation restoration.
Key words: desertification reversion, land use readjustment, rangeland-cropland-interlaced belt,
shelterbelts, “small biosphere”.
ÍNTRODUCTION
China is suffering from large scale and severe desertification. There are 593,000 km2
of sandy deserts, 569,000 km2 of Gobi deserts and 371,000 km2 of apparently deserti-
fied land in China (Zhu Zhenda et al. 1994). More than 60% of the desertified land is
located in the regions known as the rangeland-cropland-belt. China has a long history
of combating desertifícation. Since the foundation of the People’s Republic of China
in 1949, particularly since 1978, much more attention has been paid to desertifícation
control. Great achievements and progress in the aspects of revegetation, rangeland
improvement and soil conservation have been made in the affected areas. Some ac-
ceptable and practical techniques, successful demonstrations, as well as extention
models for combating desertification have been developed at grassroot, community,
local and national levels. About 42,870 km2 of land affected by desertification has
been rehabilitated in the recent 5 years, out of that 29,500 km2 have been re-afforested
and revegetated. However, desertification has not been held back. Under the pressure
of rapid population growth and the less developed economy, the general tendency of
desertification in the whole countn is still accelerating. More than 2,100 km2 of pro-