The major ecological site factors controlling the sensitivity of sub-tropical ecosystems to acidic deposition have been discussed.The index system of the relative sensitivity class has been put forward.The relative sensitivity class of ecosystems in East China has been mapped,based on a lot of information.The results indicated that the sensitivity of ecosystems in the studied regions has a significant difference,the most sensitive and sensitive areas account for more than 1/3 of the total areas in the region,mainly distributed in Fujian province,Zejiang province and Jiangxi province. 

This paper deals with the impact of the stocking density of silver carp(Hypophtyalmichthys moltrix) and big head carp(Aristichthys nobilis) on community structure of plankton in different fish ponds.The results indicate that the eutrophication of ponds is progressing after stocking silver carp and big head carp in shallow ponds(average depth 1.5～2.0 m).Accompanied with the increase of silver carp and big head carp,the utilization ratio of the primary production has been impmved and the standing crop of phytoplankton had not been decreased.On the contrary,the density of phytoplankton had increased.The individual size of phytoplankton and zooplankton had become smaller with the increase of stocking density of silver carp and big head carp. Meanwhile,the community structure of organism in water became more steady.Within suitable rang,the stocking density of silver carp and big head carp did not have significant inference on the diversity index of phytoplankton and zooplankton in intensive fish ponds. 

The results of energy flow comparative analyses of slop agroforestry systems and farmland systems in hilly area of Sichuan Basin showed that the energy accumulation rate,the solar energy utilization efficiency and the auxiliary energy conversion efficiency of agroforestry systems were higher than those of the farmland systems. 

The desert vegetation of the middle part of Hexi Corridor was classified and ecologically described on the basis of desert vegetation investigation.The important role of desert vegetation in the improvement of rural eco-environment in this area has been discussed,and the approaches of protecting and utilizing desert vegetation and the ways of improving the environment have been pointed out. 

The effects of acid rain,dust fall and their complex pollution on the growth and feeding behavior of cabbage caterpillar have been studied by indoor simulation experiment.The results show that the direct treatment had an obvious inhibiting effect and indirect treatment had an accelerating effect on growth and feeding of cabbage caterpillar.It has been noticed that soluble sugar and protein were accumulated in polluted plants and that is one of the main causes accounting for severer insect pest problem. 

This paper introduced the developing situation of forest ecotourism in China,analysized the impacts of forest ecotourism upon ecological environment,and the relationship between social carrying capacity and ecological carrying capacity.Besides,the paper stressed the importance of abiding the ecological economic principle while exploiting and utilizing the tourist resources.The authors in this paper.for the first time in China,put forward an idea of establishing forest ecotourism orientation station,and discussed the establishing conditions,study contents and study meanings.The stations will play an important role in the sustainable development of Chinese’s ecotourism. 

The toxicity,the avoidance ability and the real hazard of deltamethrin on fish and shrimp have been studied by indoor and outdoor experiment.The results show that the LC50-24h of deltamethrin to carp is 1.0μg/L,the LC50 -3h of deltamethrin to Japanese shrimp is 0.41μg/KL.If deltamethrin be used with prescript dose in paddyfield,it will have no harmful effect on fish breeding in paddy field and nearby fish pond,but will be more harmful to shrimp.Since shrimp has an obvious ability to avoid deltamethrin,so that the real harmness of deltamethrin to shrimp in natural water may by less than in the indoor experimental condition.

The effects of clipping on production of grassland dry matter in Hong Kong has been studied using different clipping frequency.The results show that:(1)Production of dry matter declined significantly with clipping,and the more frequent the clipping,the more the production dropping.(2)The grasses were more effected than woody plants and other herbs by clipping.(3)Repeated clipping for long term had a severe effect on production of dry matter.Once the net primary productivity of grassland be depressed,it should take a long time to be restored. Low clipping frequency is suggested in order to keep the productivity of dry matter in grassland of southern China.

The conception and connotation of agroforestry,the historical certainty of the abrupt rise of modern agroforestry,and the unity of economic,social and ecological benefits resulted from agroforestry in mutual promotion and coordinate development of agriculture,forestry and animal husbandry are described,which fully disclosed the important position and roles of agroforestry in rural sustainable development.

Long known as a toxicant to the physiological and biochemical processes of many plants,fluoride disturbs photosynthesis,respiration,biomembrane and metabolism of some organic compounds,accelerates the abnormal senescence and increases the possibility of genetic aberration in plants.Although all these effects are invisible injury,they play a key role in the level of visible injury.In this paper,the impacts of fluoride on these activities are reviewed,and some subjects for future research are put forward based on the conclusions. 

This paper introduces in detail the main types and characteristics of alternative agriculture in the world.The differences between ecological agriculture in China and alternative agriculture in developed countries,and the major existing problems of alternative agriculture in the world are discussed.The world trend of alternative agriculture development is also predicted.

The principles and technologies of disease,pest and weed control for organic agriculture in other contries have been introduced.The control measures include quality varieties adopting,diversified planting,rational crop rotation,microbial pesticide and inorganic fungicide applying,and other physical and biological control approaches.All the control measures are quite valuable as references to organic agriculture and organic food production in China. 

The research on the persistent of 14C-chlorsulfuron and its effect on the after reap rice through technique of nuclear trace shows that one wheat season after its application,about 25% of the chlorsulfuron remained in the soil.The residue raised with the increment of the application amount of chlorsulfuron. After one rice season and one wheat season(326 days),the residue of chlorsulfuron accounted for about 15% of the privitive dose.The residue of springapplied chlorsulfuron was higher than the residue of autumn-applied chlorsulfuron.The residue of chlorsulfuron in wheat stubble soil had a marked effect on the growth of after reap rice.The residue in root is much higher than in the other parts of the plant,which explains clearly that the negative effect of chlorsulfuron on the growth of root is related to the high accumalation of chlorsulfuron in root. 

This study was carried out with apple trees aged 15～20 years.in two apple orchards where asomate had been used as a fungicide for 7～10 years.Arsenic contents in soil and in tree tissues such as roots,cortices,shoots,leaves and fruits were investigated.The results show that the arsenic accumulated in fruits did not exceed food hygienic standard;the arsenic contents in cortices,shoots and leaves were several to more than ten times higher than those in uncontaminated orchards;The highest arsenic contents were found in cortices and spur leaves;Arsenic contents in shoots and leaves were closely related to those in cortices;Arsenic was slightly accumulated in top soil,but will have no significant effect on soil eco-environment. 

The degradation of photo-biodegradable polyethylene film and normal polyethylene film treated by natural sunlight,simulated sunlight and microorganisms have been studies.The results showed that the photo-biodegradable polythylene film splited easily into fragments after treated by natural and simulated sunlight,and many small holes accrued in the film after treated by compost.