Fjölrit RALA - 05.12.1999, Blaðsíða 102

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Transformation of desertified land in Northern China
desertification. Therefore, the theoretic approach to the eco-balance between anthro-
pogenic pressure and resource capacity in this zone should include dividing, transfer-
ring and reducing the anthropogenic pressure on the whole region. That is to say, the
grazing pressure on the large area of sandy rangeland should be decreased and at the
same time the cropping pressure should be increased on the wet land in the inter-dune
depressions. For realizing this theoretic approach, some new pattems of pasture-
agriculture interlacing system with higher production and higher population support-
ing capacity must be created.
New patterns of pasturage-agriculture interlacing modelsfor
transformation of desertified land
Desertification reversion process must be realized by a series of land use readjusting
measures and new pattems of pasturage-agriculture interlacing models. In this range-
land-farmland interlaced belt, there are generally three major types of severely deserti-
fíed land. Each different type has its own cause of desertification and characteristic
fragilities, and needs a specifíc model for transformation.
In the regions where sand dunes are densely distributed, desertifícation reversion is
very difficult to achieve. Through several years of experiments and demonstration
services, the Naiman Experiment Station of Desertifícation Research, Chinese Acad-
emy of Sciences, jointly with the people in the demonstration village, has developed
an eco-model named ‘small biosphere’, which can promote the above mentioned theo-
retic approach to be realized (Liu Xinmin et al. 1995).
This small biosphere model basically consists of three small circular zones. The
‘core zone’ is arranged in the center part, occupying about 1 to 4 ha of wet land,
equipped with one or two wells and pumps for irrigation in drought season and culti-
vated with productive crops such as wheat, maize, rice and fodder crops. It is used for
food and fodder production. The out-fringe of the core zone is a ‘protective zone’,
covering abbut 10 to 20 ha of sandy land or sand dunes, where shelterbelts and wind-
breaks are planted, and some psammophytic shmbs planted for íuel materials as well
as for sand control. The houses and the animal yard are also arranged in the protective
zone. Outside of it is a circular shaped ‘buffer zone’, occupying about 100 to 200 ha
of sandy land or dunes. As a transitional belt between the protected zone and the bare
drifting dunes, this buffer zone is used for light grazing, allowing 0.2 to 0.3 sheep
units in one ha, or even forbidding grazing in the beginning of the small biosphere
construction for vegetation establishment and to reduce the movement of sand. With
the increase in crop and fodder production in the core zone the stocking rate on the
surrounding sandy rangeland can be decreased gradually. This model can both reduce
poverty and protect vegetation. Each small biosphere is managed by one family,
which consists of 4 to 6 people. This way the income of the family has increased from
less than 5,000 RMB yuan to more than 40,000 yuan in 5 years; the rangeland re-
source has been restored and the environment improved.
In the regions with larger areas of rain-fed cropland, which has intruded in the
rangeland area, the heavy population is generally concentrated in big villages sur-
rounded by larger areas of rain-fed farmland with lower production and severe soil
erosion. An inappropriate, even erroneous strategy, which the local farmers adopted
for dealing with the ffagile conditions, was the over-expansion of cropland area. The