Based on the strict and long-term grazing test and quadrate investigation, we revealed the dynamic succession of plant community and species diversity as well as mechanism of species losses under the grazing condition. The main results are (1) The community appearance characteristics and composition become dividing obviously under stable different grazing pressure. (2) The continued intensive grazing causes the species losses and decrease in a diversity, this provides partly basis for understanding the modern species disappearance and extinction. The species extinction was due to destruction of habitat by human being. Destruction of habitat leads to species disappearance in local istrict. Accumulation of the species losses in local district may lead to the species true extinction. (3) The grazing influence the species composition and (3 diversity in both the temporal and spatial dimensions.
The structure, function and benefits of the rice-duck agroecosystem were studied. The results showed that rice and ducks co-grew well all day during most of rice growing seasons with a density of 300-375 ducks per hectare paddy field and benefit each other. Rice ecosystem provided foods and habitat for ducks, on the other hand, ducks canght and fed on insects and weeds in the field, and their waste was also a kind of good organic fertilizer for the rice. The activities of ducks could help to decrease or control the harms of pests, diseases and weeds and improve rice-growing environment such as soil fertility, soil quality and so on. As a result, this kind of farming system could produce green food rice. The economic income of the rice-duck farming system was 808.5 yuan·hm-2 higher than that of rice mono-farming system conducted by most farmers in China now. So the popularization and application of rice-duck ecosystem may have good ecological, economical and social effects.
This paper analysed the absorption and the attenuation of photosynthetically active photon (PPFD) in different plant population in three agroforestry systems. Furthermore, the distributions of light intensity in spatial and temporal dimension were also analysed. The results were as follows: The model of Ginkgo biloba leaf and fruit utilization-leguminous crop can capture 92% of the incident PPFD, with high efficiency of light utilization, and the attenuation of PPFD through the canopy was appoximated by Beer's law. The relationships between photon absorption, leaf area and aboveground biomass were fitted the equation Y=axb. Meanwhile, the wood and fruit utilization Ginkgo biloba trees can be allocated in the toppest strata for their high light transmissivity and variation coefficient of light intensity, but their canopy structures needed to be regulated. The changes in light intensity with time were affected by the condition of canopy structure and solar movement.
Two coastal reservoirs (Chisha reservoir and Dashuiqiao reservoir) and one mountain reservoir (Chishijing reservoir) in Guangdong Province were sampled in flood and dry reasons of 2000 and their plankton communities were analyzed. The composition and abundance of plankton are different in the reservoirs. The main causing factors are nutrient input and temperature. The measurements show that N/P ratios in the three reservoirs were higher than 15, phytoplankton growth was limited by phosphorus concentration. In flood season, thermal stratification was not found in coastal reservoirs, but it was obvious in the mountain reservoir. More psychrophilic plankton appeared in Chishijing reservoir, such as Ochmmonas mutabilis, Daphnia hyalina. The cell abundance of Pyrrophyta in summer is higher than in winter. Thermophilic plankton more frequently presented in the coastal reservoirs, for examples, Euglena viridis, Phacus sp. Cryptomonas sp. Psammophilocyclops so. was only found in warm areas of Dashuiqiao reservoir.
The trophic state and plankton distribution were investigated in a newly constructed reservoir (Feilaixia reservoir) in 2000. Being a throwflowing reservoir with a retention time of 15 days, its trophic state was high after inundation but decreased rapidly. During investigation, it was mesotrophic with low abundance of phytoplankton (0.39×106 cells·L-1) and zooplankton (52 ind·L-1). 29 species of phytoplankton and 53 species of zooplankton were observed in the reservoir. Cyanophyta and Chlorophyta predominated numerically in flood season and then Bacillariophyta in dry season. The abundance of zooplankton was a little higher in flood season than in dry season and predominated numerically by rotifer and nauplii. Although the trophic level in Feilaixia reservoir is a little high, it has low abundance of plankton for it's a throughflowing reservoir with high water runoff.
The oil shale dump in Maoming, Guangdong, formed by a process of oil shale excavation, separation, combustion and refining, is a huge man-made degraded ecosystem, up to 667 hm2. The soils in the oil shale dump, mainly composed of a mixture, including oil-refined shale and surface soil coming from the oil shale mine, is extremely dry, infertile, and somewhat toxic resulted from heavy metals. After an 20 years' natural succession, there have colonized only 66 species of vascular plants belonging to 24 families and 59 genera on the completely barren oil shale disposal soil. Among them, 67% of total species and 80% of total coverage are made up of Poaceae, Cyper-aceae, and Compositae. The community construction and the composition of species are very simple and still in the early stage of secondary succession. This dictates that the natural vegetation in the secondary bare land piled by oil shale residue was rather slow. So it is necessary to add up artificial measures to speed up the vegetation restoration for mitigating pollution and improving the environment.
Trees can effectively absorb and block poisonous gases, such as SO2 and NOx, when they are growing. But they can also in-crease the content of poisonous gases in forest and its near area owing to interception. The contents of SO2 and NOx in and near the forest were the highest during the growth period of leaf and branch, and were 5.2 and 6.7 times respectively the content during the growth of height and diameter. In the growth period of leaf and branch, the content of SO2 was higher in the morning and lower in the afternoon, and the content in the morning was 4 times higher as much as in the afternoon. It also showed charicteristic of being highest in the forest belt and lowest outside the forest belt, but the content of NOx was lowerest at noon. In the growth period of height and diameter, contents of SO2 and NO, in the atmosphere were high in the morning and were 3-5 times higher than that in the afternoon. In slowly growing period, the contents of SO2 and NOx changed little. The content of SO2 increased continuously from the morning both in and outside the forest belt, the content of NOx increased more rapidly outside the forest belt, and varied litde in forest belt and inside of forest belt. The peak period of growth of height and diameter was preferred for rest, tour and bodybuilding.
Mikania micrantha H.B.K is a sprawling vine of the family Compositae originated in South and Central America which has become a serious weed in Southeast Asia as well as in South China. Because of the potential pollution to the environment of chemical control, biological control seems promising. A great deal of work shows the possibility of using fungi and insects. The natural enemy Acanthopsyche sp. is firstly discovered and reported in China. Our discovery offers a new possible biological control agent of Mikania micrantha H.B.K.
Kandelia candel simulated wetland was set up in a greenhouse. The system consisted of three subsystems, one-year old K. candel seedlings, sediment and water. The synthetic oily wastewater with five various concentrations, i.e. 50 mg·L-1, 100 mg·L-1, 200 mg·L-1, 400 mg·L-1, 800 mg·L-1 and 15‰ artificial seawater (CL i.e. control) had been discharged into wetland twice a week for one year. The effects of oily wastewater on the growth of K. candel seedlings are as follows; Applied with oily wastewater at concentrations of 200 mg·L-1, 400 mg·L-1 and 800 mg·L-1, some seedlings expressed damage symptoms including curling of the leaves, chlorosis, with reddish pigmentation etc. To the 800 mg·L-1 group, seedlings expressed damage symptoms firstly and the number was the most. The survival percentages of seedlings applied with 200 mg·L-1, 400 mg·L-1 and 800 mg·L-1 oily wastewater were 95.92%、85.18% and 59.25% respectively. Discharge of oily wastewater at lower concentration could stimulate the seedling growth of K. candel. As to the 50 mg·L-1 group, yearly increment values of stem height, stem diameter and biomass were higher than CL with very significance level. Treated with 200 mg·L-1 oil wastewater, yearly increment values of stem height, stem diameter and biomass were close to CL. To the 100 mg·L-1 group, yearly increment value of stem height was higher than CL significantly. As to the 400 mg·L-1 and 800 mg·L-1 groups, plant growth was obviously inhibited. As a conclusion, K. candel had resistance and adaptability to oily wastewater, but oily wastewater at higher concentration would be harmful to K. candel.
Leaf anatomical characteristics of five dominant species, Pinus elliottii, Acacia mangium, Acacia auriculaeformis, Psychotria rubra, Albizia falcata of rehabilitation vegetation in Heshan, Guangdong, China,were studied. Results showed that there are variations in the thickness of adaxial and abaxial cuticles, the thickness and shape of cell wall, the differentiation of leaf spongy tissue and palisade tissue in mesophyll, the structure of leaf bundle of the endoderm. It provided an experimental data for further study of leaf anatomical characteristics during the restoration process of vegetation.
Zhelin Bay and its adjacent seawater were surveyed from July, 2000 to July, 2001. 57 species of planktonic copepod were found, among which Paracalanus crassirostris and Oithona brevicornis were the most dominant species, accounting for 66.7 percents of total copepod individuals. With annual average of total copepod individuals up to 5.4×103 ind.·m-3, copepods were abundant in Zhelin Bay. The horizontal distributions of species numbers and total individuals of planktonic copepods in the investigated area showed a general increase from inner bay to the outside of it. During the investigation, annual variations of them appeared in a single-peak, accompanied by the peak period from May to October and the minimum in January.
Nannochloropsis oculata is a kind of important economic algae. A series of ecological factors of N. oculata were studied, including temperature, illuminations, salinities and carbon dioxide concentration.The orthogonal designing method was used to study the effects of N, P, Fe on the growth of N. oculata. It was shown that the suitable environmental conditions for N. oculata are as follows: The species grows at the temperature of 0-30℃, and the highest growth occurred at about 20℃. The best illumination intensity may be from 5 000 lx to 7 000 lx. And the higher illumination intensity was better. The algae has a normal growth in medium with salinity ranging from 13.7-33.4, the best salinity was 26.9. And it prefers NaHCO3 to free carbonic dioxide. When the nitrogen concentration is 10 μmol·L-1, the phosphorus concentration is 2 μmol·L-1 and the ferrous concentration is 0.2 μmol·L-1, the N. oculata has its highest growth rate.
Overcompensation in Chlorella pyrenoidosa (Chlorococaceae) was studied. Cells cultured subsequent to 10 days dim light can produce more density and exhibit higher growth rate than control during a certain period after transferred with same initial density. The re-latinnshin between overcompensation and aleae bloom in natural environment was discussed also.
Effects of heavy metal ions Hg2+, Pb2+, Cd2+ and Cu2+ on the growth and PO4-P and NH4-N purification capacity of photo-synthetic bacterium Rhodopseumonas palustris were studied. When the concentration of Hg2+ at medium was 2×10-6mol·L-1, the growth rate of this strain became slow, and its growth was inhibited completely at concentration of Hg2+ of 4×10-6 mol·L-1. At the concentration of Cu2+ of 1×10-6 mol·L-1, its growth rate became slow. Its growth was inhibited entirely while concentration of Cu2+ was high up to 8×10-6mol·L-1 too. while the concentration of Cd2+ at medium was 4×10-5 mol·L-1, the lag phase of this strain was delayed, and the growth of this strain was inhibited completely while concentration of Cd2+ was 16×10-5 mol·L-1. But the growth rate of this strain was hardly influenced when the concentration of Pb2+ at medium was 8×10-4 mol·L-1. While the heavy metal ion at medium was below the concentration inhibiting the growth of this strain entirely, PO4-P and NH4-N purification capacity of this strain was hardly influenced.
Shenzhen Bay is one of the most important wintering ground of the endangered Black-faced Spoonbill. In the winter of 1999-2000, 178 Black-faced Spoonbill (25% of the world population of the species) wintered in Shenzhen Bay. Over the years, the number of wintering Black-faced Spoonbill of Shenzhen Bay has gradually increased. One possible factor for such an increase is the deterioration of surrounding wetland habitats, which forces the Black-faced Spoonbill to aggregate at Shenzhen Bay. The rapid shrinking of its essential living environment will jeopardize the long-term survival of the species. In view of the threats and problems facing the Shenzhen Bay ecosystem, the authors provide suggestions for the protection of the wetland environment.
To enhance the biochemical degradability of the wastewaters from the medicine manufacturer, especially those of high containing COD discharged from the production of anti-bacterium and anti-virus medicine, improving their biochemical degradability is one of the factors to better the treatment of wastewaters of this kind. In this paper we present the iron electrical chemical method adopted for pretreatment of the wastewater mentioned above. The results showed; the wastewater from medicine production can be properly treated, with its biochemical degradability (BOD5/COD) improved by 50%.
Waste water discharged from Guangzhou Branch of China Petrochemical Corporation Limited has high concentration of ammonium and low COD/NH4-N ratio.The waste water is treated by oxidation ditches and the removal efficiency of ammonium nitrogen is unstable. A zeolite percolator bed (ZPB) was developed and used to uptake and remove the ammonium nitrogen, organic compound, turbidity, etc. The oil refinery wastewater after treated by an oxidation ditch system and settlement process was fed to the ZPB continuously. The filtering velocity was 1 m·s-1. The results showed that the ammonium nitrogen removal efficiency by ZPB was greater than 99% within the high effective period, and the averaged COD removal efficiency was about 24.8% by ZPB system. The removal of ammonium nitrogen and COD by using ZPB system was much better than those of activated charcoal bed (ACB) system and ceramisite particle bed (CPB) system.
Simulation test of the acid sulfate soil (ASS) included 5 treatments. They were 30% of field capacity (FHl), 70% of field capacity(FH2), inundated (INU), air-dried (DRY), and naturally air-dried (NAD). The test indicated that water was an important factor on the transformation between the forms of sulfur of ASS such as water soluble S, exchangeable S, and pyrite S.The test showed that wet but not inundated or over dried was benefit to the oxidation of pyrite and the formation of water soluble S and exchangeable S in ASS. During the whole simulation period, the increases of water soluble S content of the ASS from big to small were: FH2 > FH1 > INU; the increases of exchangeable S content of the ASS from big to small were: FHl > FH2 > INU; the decreases of pyrite S content of the ASS from big to small were: FH2 > FHl > INU.Significant transformation of S forms happened during the air-drying process of the NAD treatment. The dynamic of Jarosite-S, organic S and element S in all treatments are also discussed here.
In this paper, the market valuation method, shadow engineering method, opportunity cost method and substitute expense method are used to value the functions of the forest ecosystem in Baiyun Mountain. The valuation results reveal that the total ecological value is estimated up to 145.80 million yuan per annum, of which, about 14.24 million yuan is of the output of standing trees, about 4.61 million yuan of water conservancy and soil conservation, about 36.24 million yuan of carbon fixation and oxygen production, about 6.32 million yuan of the animals' habitat and biodiversity protection, 17.37 million yuan of hygiene, about 1.34 million yuan of nutrient retention for N, P and K, about 0.17 million yuan of SO2 degradation and control of diseases and pests, about 23.39 million yuan of the increase of grain output, and about 42.14 million yuan of tourism.
In order to design a reasonable and scientific layout for ecological construction of Lianping County, Guangdong Province, a comprehensive analysis was conducted with special reference to: 1) its natural resources of climate, soil and land, water, forest, biology, minerals, tourism; 2) its social-economic system, including regional advantages, economic status, and manpower resource; and 3) the advantageous and disadvantageous conditions for construction of ecological county. According to the above analysis, the strategic orientation and development objectives for this purpose were put forward, and then the detailed contents for ecological construction, including ecological forestry, agriculture, industry, city, tourism, culture, and environment, were elucidated. Especially in the aspect of ecological regionalization, 4 eco-economic overall distribution areas were constructively brought forward, they are; 1) the production and life corridor along the National Highway No. 105; 2) the east water-resource protecting ecological forest cum water power development area; 3) the west reserve and eco-tourism area network; and 4) the southeast complex eco-agricultural and eco-city construction area. Some important projects that should be preferentially conducted, and their key techniques and strategic security measures were also put forward in the end of this paper.
With the rapid development of national economy, requirement of people for natural resources and the environment has been increasingly expanded. Thus, timely, exact and dynamic information of resource state and its dynamics is vital to the conservation of resources, protection of the environment and sustainable development. This paper gives an overview of the concepts, characteristics of 3S technologies, i.e., remote sensing (RS), Geographic Information System (GIS) and Global Positioning System (GPS); application of 3S technologies in landscape ecology, landscape heterogeneity research and spatial pattern analysis and simulation. Future advance of the application of 3S technologies in community ecology, vegetation survey, biodiversity research, vegetation mapping and many other ecological fields are also discusses in this paper.
Volatile organic compounds (VOCs) that are produced by and emitted from plants play key roles in several aspects of tropo-spheric chemistry, including ozone dynamics, carbon monoxide production, and methane oxidation. Isoprene and monoterpene, the two most abundant and best studied VOCs, are introduced in this article. Isoprene emission is strongly dependent on light and temperature and has large variations in different species, while monoterpene emission is usually independent of light. Methanol and other compounds are also simply mentioned. We also analyze the relationship between the emission of VOCs and global change.
Photosynthetic bacteria was applied abroad in environmental protection and humans lives. Many scientists in microbiology, aquaculture and environmental science paid great attention to it for its particular character. This paper summarized the current application of photosynthetic bacteria in aquaculture and organic waste water disposal.
