Table of Content

10 December 1998, Volume 17 Issue 06

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Effects of Doubled CO₂ Concentration on Leymus chinensis in Grasslands

Lin Shunhua, Gao Leiming, Huang Yinxiao

1998, (6):  1-6. 

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The ecophysiological effects of doubled CO₂ concentration on Legmus chinensis which is a good herbagae in grasslands were studied.The results showed that doubled CO₂ concentration could promote the physiological process of Leymus chinensis,such as:increassing net-photosynthesis rate and water use ratio and reducing water loss of leaf. It specifically showed that the stomatal resistance increased 4% to 13%, the transpiration rate reduced 6% to 13%, the Net-photosynthesis rate increased 49% to 87%,and the water use efficiency increased 65% to 101%. This kind of increase trend could continuously appear in every phenological period. This indicated that the Net-photosynthesis rate of the Leymus chinens is did not produce downward“acclimation”under high concentration of CO₂ within a vegetative season. Doubled CO₂ concentration made the physiological process active and accelerated its phenological couse as well. The changes of physiological and biological characteristics mentioned above were mutually affected and promoted. Doubled CO₂ concentration increased the biomass of the Leymus chinensis. Dry matter weight above ground increased 10.4% to 23.2%, the root increased 48.4%. Root/shoot ratio is obviously increased. In general, the physiological effect of doubled CO₂ concentration on the Leymus chinensis was positive and could increase bioproductivity.

Studies of Distribution Pattern of Flora of Ecological and Economic Type of Protecting Forest Stands in the Huangtang Small Watershed

Yuan Zhengke, Zhou Gang

1998, (6):  7-13. 

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Quality background data of 98 subcompartments were obtained by investigation in the Huangtang small watershed in the hilly areas of the centre of Hunan. The main factors affecting water and soil loss in the subcompartments were defined with the Quantized Theory(I).According to these factors, five ecological environment types were gained by means of the blugred assemblement.The distribution pattern of flora of the ecological and economic type of protecting forest stand was analysed on the basis of the ecological background values of each type.

The Study on Comparing the Biodiversity of the Main Forest Types in South Province

Yang Xuejun, Jiang Zhilin, Dai Guoqin, Jiang Rusheng

1998, (6):  14-17,77. 

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Based on the biodiversity investigation of the main forest types in south Jiangsu province,a comparatire analysis of biodiversity has been done among different forest types in tree layer,shrub layer and glass layer, respectively.A synthetic evaluation has been carried out.In the process,a new method, the weighted sum method of time-stability coefficient was put forword.

Influence of Reclamation of Forest Land on Nutrients and Enzymatic Activities in Soil

Zhang Chenge, Chen Xiaoli

1998, (6):  18-21. 

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The soil samples were collected from bare and fallow land, slash land and farm land along valleys in the forest areas of Ziwuling Mountains. The soil surcease, neutral phosphatase and urease as well as soil organic matter, total N and available N were analyzed. The results showed that nutrients and enzymatic activities in the soil were changed in different erosion areas of the slope land after the reclamation of the forest land. However, distribution of the nutrients and enzymatic activities in the soil profile was same. The nutriens and enzymatic activities in the soil were higher in surface layer than those in the other layers and gradually declined with increase of soil depth. The soil enzymatic activities, organic matter, total N and available N in the slash land were obviously higher than those in the forest land,bare and fallow land. This also showed that forest renewal had no negative effects on nutrients and microorganism in the soil and sometimes had positive effects. Correlation analysis showed that there were significant correlation between the activities of three enzymes and soil organic matter, total N and available N.

Effects of Aquatic Macrophytes of Various Life Form on Phytoplankton

Qiu Dongru, Wu Zhenbin, Kuang Qijun, Deng Jiaqi

1998, (6):  22-27. 

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The Effects of aquatic macrophytes of various life form on phytoplankt on were studied in the large-scale enclosures established in sublake Shuiguohu of Lake Donghu, Wuhan during June-October, 1994. The results is showed that both floating and submerged macrophytes could decrease the standing crops of phytoplankton and resulted in the changes in species composition. The coefficients of productivity vs. biomass of waters in the enclosures with macrophytes were lower than those in the control enclosure and lake water. It is also demonstrated that water hyacinth(Eichhornia crassipes)could effectively suppress the Microcystis bloom and then facilitate the proliferation of submerged macrophytes. The water blooms and physico-chemical parameters were monitored for four months. It is indicated that the competition from small-sized algae such as Cytromonas, Merispodia and Cyclotella might have principally resulted in the dissappearance of blooms of large-sized cyanophytes based on the analyses of the succession of phytoplankton communities and nutrient level among the various enclosures and lake water.

The Structure of Wetland Landscape and Models of Ecological Engineering in Dongting Lake Region

Wang Kelin

1998, (6):  28-32. 

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Dongting lake region is located in the middle reaches of the Yangtze Valley. The wetland in Dongting lake region is the largest lacustrine in China, which is 8.77?10⁵ha.It can be divided into three types: the shallow waters, thelake and river shore,and the Paddy fields.Akong with the frequent redaimation on wetlands,it has made some harmful influence on the environment, i.e., the severe flooding, inundation, and water-logging,neduced wetland areas,and degraded ecological functions.In order to utilize and protect the wetland rationally, the following measures must be taken: 1)controlling the scale of wetlands reclaimation and making great efforts to construct high-efficient ecosystems; 2)stabilizing the area of wetland; 3)strengthening comprehensive management of wetland. According to the principles of ecological engineering and previous practices, comprehensive utilization models which are suitable to the shallow waters, lake and river shore,and Paddy fields were constructed.

Synomone Induced by Herbivore Feeding

Yang guang, You Minsheng

1998, (6):  33-39,27. 

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Plants emit synomone by herbivore feeding to attract natural enemies to protect themselves. Herbivore-induced synomone indicates the presence of host clearly and specifically and plays an important role to the location of natural enemies in the search of long distance. Different plants and herbivores can induce different chemicals, so the production of synomone has the specificity of species. In addition, spatial and temporal factors regulate the production of synomone. Research on chemical ecology of synomone shows that the main components of synomone are “green leaf odor”, terpene and indole.β-Glucosidase in caterpillars' oral secretion is an elicitor of synomone. But some plants release synomone systemically and elicitor of which has not been known yet. There are three possible pathways for plants to synthesize synomone, namely isoprenoid pathway, fatty acid/lipoxygenase pathway and shikimic acid/tryptophan pathway.

Circadian Generator of Rodents and its Photoperiod Regulation

Cai Liquan, Li Qingfen

1998, (6):  40-43. 

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Circadian rhythm is a general phenomenon in rodents, and it is a evolutionary result from animals' environmental adaptation.The SCN(suprachiasmatic neucleus)is believed to be an oscillator in mammals. It has the ability of both generating endogenerous periodicity and synchronising the environmental factors. Gene experession of some IEGs(Immeadiate early qenes)in the SCN, e.g. c-fos, jun-B, is effected by photoperiod. Their experssion product, Fos-Jun, can regulate some clock genes' expression. Thus, photoperiod can influent on circadian rhythm by speficially regulating genes' expression.

The Vetiver Eco-EngineeringA Biological Technique for Realizing Sustainable Development

Xia Hanping, Ao Huixiu, Liu Shizhong

1998, (6):  44-50. 

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The vetiver eco-engineering, difined as planting vetiver grass(Vetiveria zizanioides)with local species of trees, shrubs, herbs and lianas by simple necessary engineering structures, is used to control soil erosion and rehabilitate degraded environments. All experiments and applications indicated that the vetiver eco-engineering provided better slope stabilization, environment mitigation and beautification than just vetiver was planted alone. For dozens of years, almost all studies and observations on vetiver grass(Vetiveria zizanioides)have indicated that the perennial had wide adaptation to the environment and strong resistance to adversity. Apart from its great success as a biological measure of soil and moisture conservation, the vetiver eco-engineering also has a multitude of other excellent functions. It can increase nutrients and moisture in soil,improve agricultural micro-climates, recover deteriorated eco-systems, and ameliorate polluted lands. Therefore, extending the vetiver eco-engineering, particularly in mountain villages, is an efficient measure for realizing the rural sustainable development. It has been testified that agricultural ecosystems, in which vetiver is acted as a pivot, may produce tangibly ecological, economic and social benefits. Obviously, the vetiver eco-engineering has wide application prospect for soil and moisture conservation and for establishing complex eco-agriculture in the tropics and subtropics as well as in mountainous areas of southern China. However, in order to popularize,develop and utilize this measure, it is necessary to ensure the newly biological technique.

Current Situation and Development Tendency of Researches of Non-Point Source Pollution in Agriculture

Zhang Shuilong, Zhuang Jiping

1998, (6):  51-55. 

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Four research aspects of agricultural non-point source pollution at home and abroad,i.e., mechanism of occurence, expansion and transformation; impact on water environment; modelling;and control and management are reviewed.Their development tendency is also discussed. Based on analysis of the current situation the ways of research suitable to actual condition in China are proposed.

Aeroanion Researches in Evaluation of Forest Recreation Resources

Zhong Linsheng, Wu Chucai, Xiao Duning

1998, (6):  56-60. 

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Aeroanion is of benefit to human health and the concentration of aeroanion has been used as an index for evaluating quality of forest recreation resources. The recent development of studying aeroanion as the forest resources was generally introduced and discussed in detail in the paper.

Food Hoarding Habit of Meriones unguiculatus

Li Zhonglai, Zhang Wanrong, Qi Mingyi, Fan Xiongying, Du Zhixue

1998, (6):  61-63. 

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The food hoarded by Meriones unguiculatus in the barns with three kinds of habitats in Erdosi desert-grasslands were investigated in the period of Nov. 1～10th, 1989. The results showed:(1)96% of the food composition in their barns were Corispermum seeds, Tribulus terrestris seeds and Bassia dasyphylla ;(2)The annual seed plants of Chenopodiacase was favorite food of M. uniguiculatus. There were dense population of M. uniguiculatus and more barns and food stocked in habitat Ⅰ.(3)The correlation between the population of M. uniguiculatus and its barn numbers was positive(P<0.001), the regression equation was(barn number)=0.3443+0.1228(density of M. uniguiculatus);and(4)There were no significant difference of the barn volumns among three kind habitats(P>0.10).

A Preliminary Investigation of Ecological Issues Arising in the Man-made Forest of Eucalyptus in China

Wang Zhenhong, Duan Changqun, Qi Lianchun, Zhang Shibiao, Xu Yihong

1998, (6):  64-68,55. 

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The findings about the man-made forest of Eucalyptus in China and other countries in recent years are reviewed related ecological problems,such as the decrease of soil fertility,the loss of biodiversity and the simptified structure the man-made forest are pointed out in development of Eucalyptus plantations in China. For making use of Eucalyptus advantages, some suggestions are put forward in the paper.