5 CONCLUSION
In the south-eastern sandy land in Horqin in northern China, enclosing
grasslands within a shelter belt of Populus × beijingensis(FG) or raising in them Pinus sylvestris var. mongolica orUlmus pumila in widely distributed but small pockets increased
the accumulation of C in the ecosystem (in plants and in soil)
significantly. Mainly because of the differences in the tree species,
the C pool was the largest in FG. Biomass C in all the three treatments
was also significantly higher than that in the control. The greatest
increase in soil C was in the upper layer of the soil profile (to a
depth of 50 cm). All the three approaches will contribute greatly to C
sequestration globally and are suitable for arresting desertification in
semi-arid areas that may be lacking in adequate levels of soil moisture
and available nutrients.