Integrated Farming Systems at Different Scales 465are suitable for growing economic or cash forest. Accelerated development of cash
forest plantations is absolutely necessary in order to mobilize participation to over-
come difficulties due to shortage of funds for long-term silvicultural programmes
in mountain areas. Economic forests are a special category which are mainly used
for non-wood products such as fruits, edible oils, fibres, pharmaceuticals, resins,
gums, waxes and many other raw materials for industrial and commercial pur-
poses. In the subtropical area of the lower reaches of the Yangtze River the most
widespread species with economic potential are tea oil trees (Camellia oliefera),
tung tree (Aleurites fordii, A. montana, Sapium sebiferum), Chinese walnut (Juglans
regia), Chinese chestnut (Castanea mollissima), lacquer tree (Rhus verniciflorum),
star anise (Illcium verum), eucomia (Eucomia umoides), and citrus fruit groves (Cit-
rus reticulata), Litchi chinenses and Euphorbia longgan. Slopes of more than 20°
gradient and hills need tree or scrub species to conserve water and soil. The com-
mon species of timber used for soil protection are Pinus massoniana, Pinus elliottii,
Cunninghamia lanceolata, Quercus accutissima, Eucalyptus robusta, Sassafras tsumu,
Robinia pseudoacacia, Ailanthus altissima, Albizzia julibrin and Paulownia fortunei.
In recent years, after overall planning and comprehensive improvement, a number
of red earth areas that were low yielding in the past have changed dramatically.
In the Yangtze River Basin there are about 60 tree species, 20 shrub species and
more than 30 herb species (not including those existing in silviculture environ-
ments) used for protective forest construction. Most of these species are indige-
nous, a few exotics suitable for these areas were also introduced, based on experience
and observation in small-scale plots. Community structure and stand density
determine forest function. They also affect ecological and economic benefits of the
protective forest. Table 18.19 shows the major tree species for reforestation and
their planting density in the Yangtze River Basin.
Effects of afforestation for environmental protection and regional
development
- Improving the environment
Seven years after the implementation of the Yangtze River Protective Forest Project,
the environment of the Yangtze River Basin has been improved significantly. It is
estimated that 2,707,500ha of multifunctional protective forest have been refor-
ested during the Eighth Five Year Plan period in the upper reaches of the Yangtze
River (Lu, 1996). The vegetation cover of the whole Yangtze River Basin has
increased over 5 per cent. The proportion of protective forest and mixed forest has
increased nearly 100 per cent. Most of the reforested woodland stands have closed
and grown well. Shrub and herb layers of stands have developed rapidly. As a con-
sequence, loss of water and soil has been primarily controlled and the area of soil
degradation has been greatly reduced (Yang, 1993). In Xingguo County of Jiangxi
Province, for example, the area of soil erosion was reduced from 160,000ha to
50,000ha and forest cover has increased 20.8 per cent, as compared with the 1980s.
This previously well-known ‘desert area of the southern Yangtze River’ for water