An agro-forestrial intercopping field experiment on Choerospondias axillaris cropped with Arachis hypogaea was undertaken in Subtropical China,to study the effect of agro-forestrial intercopping on photosynthetically active radiation(PAR) and yield of crop.The results showed that there was a significant decline in PAR and A. hypogaea yield in agro-forestrial systems.Compared to sole A. hypogaea , A. hypogaea yield in equivalent area was decreased by 35.9% and 44.6% in 5 year old and 9 year old Choerospondias axillaris agro-forestrial systems,respectively.In addition,there was a significant spatial variability of PAR and A. hypogaea yield in agro-forestrial systems,and they increased with distance from tree line.Moreover, A. hypogaea yield had a significant correlation to PAR,which indicated that competition for light is one of the key factors to decrease yield of A. hypogaea .
Problems in water-land resources and environmental quality increase with the fast economic development in the coastal region of southeastern China. This region has the highest density in population, industry and towns in China, and the large export-oriented economy makes itself a strategic importance while China enters into international markets. The problems facing to this region include arable land reduction, land degradation aggravation, high percentage of built-up land with high rate of expansion, expanded non-point pollution, deteriorated water quality, decreasing biodiversity, destroyed ecosystems, severe air pollution, frequently occurred acid rain, and multi-pollutants. The important research fields in the near future should include a) influence of high-intensity exploitation of resources on changes of environment quality and its feedback; b) interface processes, key mechanisms and adjustment principles for degradation of water-, land-, and air-resources and environmental quality; c) evolvement processes and nurturing theory of biodiversity and ecological resources; and d) spatio-temporal variation and human-induced effects on regional resources and environment quality. Strategies for sustainable development in the region are as follows: a) controlling to ensure basic cultivated land area; b) enforcing remediation of polluted water environment, and controlling non-point pollution; c) strengthening ecological construction and ecological security; and d) controlling multi-pollution and preventing trace toxic pollutants.
ZHAO QIGUO Institute of Soil Science, the Chinese Academy of Sciences, P. O. Box 821, Nanjing 210008 (China)
