Table of Content

10 August 2006, Volume 25 Issue 08

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Articles

Effects of alpine meadow degradation on clonal growth characteristics of Lagotis brachystachya

ZHOU Huakun; HAN Fa;ZHOU Li;ZHAO Xinquan;LIU Wei

2006, 25(08):  873-879 . 

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This paper studied the effects of alpine meadow degradation in the source region of Yangtze and Yellow Rivers on the clonal growth characteristics of typical stolon plant Lagotis brachystachya. The results showed that on degraded alpine meadow, the stolon number and branching intensity of L. brachystachya increased, and the genet and ramet were lower but their roots were longer than those on the non-degraded alpine meadow. No significant difference was observed in genet leaf number, but the ramet leaf number on degraded alpine meadow was significantly more than that on non-degraded alpine meadow. The stolon length, diameter, and leaf number of L. brachystachya were larger on non-degraded than on degraded alpine meadow, and the energy allocatgion of L. brachystachya for clonal reproduction was more on non-degraded than on degraded alpine meadow. The dry mass proportion of genet was less on non-degraded alpine meadow than on degraded alpine meadow, while that of ramet and stolon was in adverse. All of these were the responses of L. brachystachya to the variations of habitat caused by alpine meadow degradation, and the most reasonable status of this plant for its resources utilization and habitat adaptation.

Analysis and assessment of climatic dry and wet conditions in Shiyang River Basin

LIU Mingchun^1,2

2006, 25(08):  880-884 . 

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In this paper, the spatial-temporal distribution and evolution trend of precipitation in the water-use area of Shiyang River Basin in Hexi Corridor was studied, and the water balance in different reaches of the Basin was calculated by using potential transpiration, arid index, and difference of transpiration and precipitation. The results showed that during the period of 1980s-1990s, the total precipitation in the Basin had a gradual but slight increase. The recipitation increased in spring and summer but decreased in autumn and winter, while the annual mean potential transpiration was 1 026.1 mm, with a gradual increase from upper to lower reaches. In 1970s-1990s, the potential transpiration had an increasing trend, with an annual average of 4.1-43.6 mm, but decreased in the order of summer> spring>autumn >winter, with an average ranging from 403.5 to 521.6 mm. The average arid index was 0.002, with a maximum of 0.581 in the lower Minqin region. During the past 30 years, the climatic arid index of this Basin increased, indicating a dryer and dryer climate, and the average annual lack of water was 810.7 mm, suggesting a severe deficit of water resources. A reasonable water resources deployment proposal was suggested to response this climatic change and to promote a sustainable regional economic development.

Soil microbial quantity and its relations with ecological factors in northern alp region of Hengduan Mountains

SHAO Baolin¹;GONG Guoshu¹;ZHANG Shirong²;YU Xia¹;YANG Danling¹, ZHANG Hong¹; LIU Xiaolu¹

2006, 25(08):  885-890 . 

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With the help of GPS (Global Position System), thirtyfive surface soil samples were collected from the northern alp region of Hengduan Mountains in Qinghai Xizang Plateau. The quantities of soil fungi, bacteria and actinomycetes were determined by dilution plate technique, and their correlations with soil fertility, soil humidity, landuse type, and soil pH were analyzed. The results showed that in this region, soil microbial quantity was decreased in the order of bacteria >actinomyces >fungi, and Songlinkou>Que’er Mountain>Zheduo Mountain. Forestland was richer in microbes than grassland, but the proportion of various microbes in forestland was lower than that in grassland. A significant positive correlation was observed between soil actinomycetes quantity and soil pH value, and between soil fungal quantity and soil total potassium content. .

Fractal characteristics of soil particles under subalpine coniferous forests in Western Sichuan

ZHOU Xianrong^{1 _;}CHEN Jinsong²

2006, 25(08):  891-894 . 

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Fractal theory deals with the natural figures and images with self-similarity but without characteristic length, which offers an effective tool to quantitatively study complicated systems such as soil. Based on this theory, the fractal characteristics of soil particle size distribution under the 12 subalpine coniferous forests in Western Sichuan were studied, and the results showed that the fractal dimension of soil particles in surface layer ranged from 2.5209 to 2.7978. This fractal dimension only had a very significant correlation with the content of <0.001 mm soil particles. No significant correlations were observed between thisfractal dimension and the contents of soil organic matter, total nitrogen and pH, but there was a very significant correlation between the contents of soil organic matter and total nitrogen. The quantitative symbolization of the characteristics of subalpine coniferous forest soil by the fractal dimension of soil particle size distribution was discussed in the paper.

Dynamical changes of landscape pattern in Yulin region based on GIS

WANG Yongjun^1，2; LI tuansheng³

2006, 25(08):  895-899 . 

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By using 1∶500 000 land-use map of Yulin (1982-1998), geographic information system program ArcViewGIS 3.2 and ArcInfo 7.1, and landscape analysis program Fragstats, this paper analyzed the dynamic changes of landscape pattern in Yulin region. The results showed that in 1982-1998, the area of rassland and woodland in this region increased greatly, while that of sandy desert decreased greatly. The landscape had a higher fragmentation degree, its shape was getting more and more complex, and the Shannon’s diversity and landscape evenness indices decreased in a smaller degree. Irrigated paddy field, upland, garden land, woodland, waters, saline and alkaline land, and sandy land were mainly converted into grassland, while irrigable land and grassland were mainly converted into upland. The increment of residence area mainly came from upland, while that of industrial area mainly came from saline and alkaline land.

Multi-scale effect of topography on forest landscape pattern in Taishan Mountain.

GUO Luo¹;XIA Beicheng¹; LIU Wenqiu²

2006, 25(08):  900-904 . 

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Based on Landsat TM images and field survey data, and by the aids of 3S techniques, this paper studied the dynamic changes of forest landscape pattern in Taishan Mountain, and their relations with altitude variation. Eight topographical factors were adopted to define the topographical characteristics, and three radiant transects consisting of standard sequential sampling plots were applied to collect information on remote sensing images. The multi-scale pattern of forest landscape differentiation and its correlation with topographical parameters were analyzed by multivariate regression and main factor analyses. The results showed that topographical orientation (position), elevation, and mountain land type were the critical factors at landscape level, slope exposure and gradient were important factors, while slope shape and position were not the significant ones. In the analyses of forest landscape differentiation and gradient, the key elements were elevation exposure, slope shape and position, and elevation, with the consideration of topographical position. There were significant positive correlations among the main topographical factors, which could better explain the multi-scale pattern of forest landscape differentiation. The contribution rate was about 70% at any scale, and the explanatory percentage was increased with increasing scale while the explanatory ability was in adverse, which revealed that the effect of topographical factors on forest landscape pattern is prominent, and scale effect remains an important problem to be explored.

Soil nitrogen and phosphorus losses with surface runoff from typical vegetable field of Taihu Lake region and their control with grass buffer strip

LI Guodong^1,2; HU Zhengyi¹;YANG Linzhang¹; WANG Cairong^1,3; LIN Tian ¹; JIN Feng¹

2006, 25(08):  905-910 . 

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Agricultural nonpoint source nitrogen (N) and phosphorus (P) losses are one of the major factors resulting in surface waters eutrophication, while understanding the fluxes and chemical forms of N and P in runoff is critical to control the eutrophication of water bodies. Vegetable field is a main land use pattern in Taihu Lake region, but its N and P losses haven’t been reported. In this paper, a field monitoring study of N and P losses with surface runoff was conducted, and the effects of grass buffer strip on reducing the export of N and P from vegetable field was investigated. The results showed that the runoff export of N and P from vegetable fields during the period from October 24, 2004 to August 17, 2005 was 3 010.9 g·hm^-2 and 695.0 g·hm^-2, respectively. In the runoff, particle N and P were the predominant fractions, which accounted for 64% and 75%, and NH₄⁺-N and H₂PO₄^- were the major forms of soluble N and P, occupying 50% and 87%, respectively. The average filtering efficiency of N and P was 42%-91% and 30%-92%, respectively, and the removal efficiency of particle N and P was higher than that of soluble N and P. The present study indicated that grass buffer strip could effectively control the N and P losses with runoff from vegetable fields.

Effects of reclamation on soil organic carbon in Haibei alpine meadow

LI Yuemei^1,3; CAO Guangming¹;WANG Yuesi²

2006, 25(08):  911-915 . 

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With rapeseed fields having been reclaimed from alpine meadow for 0, 10, 20 and 30 years at the Haibei Research Station, Chinese Academy of Sciences as test objects, this paper studied the changes of soil organic carbon (SOC) and its fractions including light fraction organic carbon (LFOC) and heavy fraction organic carbon (HFOC) in 0～10, 10～20, 20～30 and 30～40 cm soil layers with reclamation duration. The results showed that after the alpine meadow reclaimed, the changes of SOC and its fractions mainly occurred in 0～10 cm soil layer, with LFOC decreased most rapidly and followed by HFOC and SOC. After the conversion from alpine meadow to cropland for 30 years, the SOC, LFOC and HFOC in 0～10 soil layer decreased by 37.64%, 48.63% and 43.97%, and their decrement in 0～40 cm soil layer was 785.77, 16.79 and 460.29 kg C·hm^-2·yr^-1, respectively. The storage of soil carbon pool was decreased from 143 516.94 to 114 298.34 kg C·hm^-2·yr^-1. Reclamation made alpine meadow as a carbon sink turn into a carbon source.

Land use change and related environmental status in Wushuihe River Basin of West Hunan Province

YANG Bosu¹;LIAO Zhongjian²;OUYANG Zhiyun³; HE Ping⁴

2006, 25(08):  916-920 . 

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With the help of remote sensing, this paper analyzed the land use change and related ecological environment in Wushui River Basin of Hunan Province. The results indicated that in 1986-2000, the forestland of this basin increased by 12.69%, uplands with a slope larger than 25° reduced by 1.13×10⁴ hm², and cultivated land and lawn increased by 16.31% and 98.10%, respectively. The annual increasing rate of water and soil erosion was 1.79%, with a moderately eroded area increased by 77.75%. Industrial wastewater discharge raised 2.5% annually, and industrial waste gas emission increased by 1.37 times. In light of these problems, more attention should be paid to the bush land protection and forest vegetation restoration, the control of water and air pollution with focus on the renovation of coal-smoke pollution enterprises, and the small scale integral management of non-point source contamination.

Leaf traits and their interrelationships of main plant species in southeast Horqin sandy land

LIU Jinhuan¹;ZENG Dehui¹; Don Koo LEE²

2006, 25(08):  921-925 . 

Asbtract ( 2097 )  

In this paper, 23 main plant species of herb, shrub and tree were sampled from southeast Horqin sandy land, and their leaf traits including fresh weight (FW), dry weight (DW), dry matter content (DMC), area (AR), specific leaf area (SLA) and thickness (TH) were measured. The results showed that the leaf traits of herb were more variable than those of shrub and tree. The average SLA was in the order of herb ≥ shrub≥ tree, DMC and DW was in reverse, while no apparent change was found in TH. A significant variation in leaf SLA and DMC was observed among herb, shrub and tree, and there was a significant correlation between these two indices, suggesting that SLA and DMC could be used to predict the plant species position along a resource use gradient. In case of leaf thickness, some variability could not be explained in this study, and thus, further studies should be focused on this leaf trait.

Phosphorus adsorption characteristics of sediments in Congming Dongtan wetland, the entrance of Yangtze River

WANG Aiping¹; YANG Shouye²;ZHOU Qi¹

2006, 25(08):  926-930 . 

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To better understand the phosphorus cycle in wetland, an experimental study was made on the phosphorus adsorption characteristics of sediments S₁, S₂ and S₃ sampled from the Congming Dongtan wetland at the Changjiang Estuary. The results showed that phosphorus adsorption process mainly happened within the first 24 h, and then arrived at a balance. The average quick adsorption rate increased with increasing percentages of fine fraction in the sediments, and the adsorption isotherm could be expressed by the Langmuir equation. According to the equation, the phosphorus adsorption capacity of the sediments was estimated to be more than 200 mg·kg^-1, and decreased in the sequence of S₁>S₃>S₂, which was possibly because of the higher percentages of fine fraction and the higher contents of TOC, Al, Fe, Ca and Mg in S₁ than in S₂. Soil temperature and pH also affected the phosphorus adsorption of sediments.

Characteristics of ammonia (NH₃) volatilization and its affecting factors of typical Calamagrostis angustifolia wetland soils in Sanjiang Plain

SUN Zhigao^1,2;LIU Jingshuang¹; WANG Jinda¹; QIN Shengjin^1,2

2006, 25(08):  931-937 . 

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With venting method, this paper determined in situ the ammonia (NH3) volatilization from the soils of typical meadow Calamagrostis angustifolia wetland and marsh meadow C. angustifolia wetland in Sanjiang Plain, and analyzed its main affecting factors. The results showed that the change trends of the NH₃ volatilization rates of these two typical C. angustifolia wetland soils were basically the same, with two peaks and a valley before the middle ten days of July, and as a whole, strictly monotony downtrend afterwards. The NH₃ volatilization rate of marsh meadow C. angustifolia wetland was relatively high, with an average value being 1.35±0.53 folds of typical meadow C. angustifolia wetland. The change trends of cumulative NH₃ volatilization amounts were also basically the same, i.e., before the middle ten days of July, they increased rapidly and the values were relative proximity, but afterwards, the values increased slowly and marsh meadow C. angustifolia wetland had a much higher value. In growing season, the total NH₃ volatilization amount of typical meadow C. angustifolia wetland and marsh meadow C. angustifolia wetland soils was 6.35 and 6.87 kg N·hm^-2, respectively. The analysis of affecting factors indicated that the storage of soil nitrogenous compounds was not the limiting factor affecting the process of NH3 volatilization, while atmospheric temperature and its caused temperature fluctuation were the important factors affecting the changes of NH₃ volatilization rate. Precipitation and the fluctuation and evaporation of soil moisture were the important inducers of the partial fluctuation of NH₃ volatilization rate, soil pH and texture were the main factors inducing lower NH₃ volatilization rate, and the integrative action of all the factors induced the changes and differences of NH₃ volatilization　rates and NH₃ volatilization amounts of the two typical C. angustifolia wetland soils.

Characteristics of light condition under viaduct and suitable greening distribution in city

WANG Xueying¹;XIN Yafen²;SONG Kun¹;DA Liangjun¹

2006, 25(08):  938-943 . 

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In this study, three sites of each E-W and S-N oriented viaducts in hanghai were selected, and the light condition and its diurnal variation under the viaducts were measured in the four seasons of a year. The special characteristics of light condition were analyzed by combining the indexes of photosynthetic photon flux, light compensation point, and light requirement level, and the results showed that the light condition and its diurnal variation changed with different viaducts, and even, under the same viaduct. The main affecting factors are the quantity of viaduct, viaduct height, width between viaduct deck and green belt, and weather condition. The heterogeneity of light condition under viaduct brought out the “dead position” and “excessive light’s damaging position” of plant grow th. It was suggested that suitable greening distribution could be effective in i mproving the growth condition of the plants under viaduct

Joint toxicity of Pb²⁺ and PDB on seed germination and seedling growth of Triticum aestiuce and Brassica Pekimensis

CHAO Lei^1,2;ZHOU Qixing¹;CUI Shuang^1,2; CHEN Su^1,2;SUN Tieheng¹

2006, 25(08):  944-949 . 

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With meadow brown soil as test soil, this paper studied the effects of single and combined pollution of Pb²⁺ and 1,4-dichlorobenzene (PDB) on the germination rate, biomass production, and shoot and root elongation of wheat (Triticum aestivum) and Chinese cabbage (Brassica pekimensis). The seeds of wheat and Chinese cabbage were exposed to various concentrations of PDB with or without lead addition. The sensitivity of test crops to the toxicity of the pollutants was in the sequence of root elongation>shoot elongation > biomass fresh weight > biomass dry weight and germination rate. When the concentration of added Pb²⁺ was 500 mg·kg^-1, lead and PDB had a synergistic effect of inhibiting shoot and root elongation. When the concentration of added Pb²⁺ was 2 000 mg·kg^-1, the pollutants had a synergistic effect of inhibiting shoot elongation but an antagonistic effect of inhibiting root elongation. For both wheat and Chinese cabbage, the joint toxicity of lead and PDB was more dependent on PDB’s concentration.

Spermarian development of six dominant locust species in Siping area of Jilin Province, China

HAO Xilian¹;ZHAO Zhuo¹;ZHOU Ge¹;REN Bingzhong²

2006, 25(08):  950-953 . 

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In the Siping area of Jilin Province, six dominant locust species were bred under natural condition, and their spermarian development was studied. The results showed that at the beginning of adulthood, spermary had a ignificant increase of its length growth but no significant increase in its width growth. Thereafter, the spermarian volume got its peak, and then declined. The spermarian development of the locusts had an obvious species difference, with the development level at adulthood decreased in the order of Shirakiacris shirakii > Oedaleus infernalis > Omocestus viridulus > Euchorthippus unicolor > E. viisttatus > Atractomorpha heteroptera, and with the spermarian volume differed, indicating the differentia of the physiological functions of spermary among locust species. According to the histological observation, different types of cells were appeared in spermary at its different development stages. The growth of spermatocyte and the accumulation of matured sperm led to the increase of spermarian volume, while mating and physiological enervation resulted in the decrease of spermarian volume.

Habitat selection of redcrowned crane in Yellow River Delta

SHU Ying^1,2;HU Yuanman¹;LENG Wenfang¹;ZHU Shuyu³;SHAN Kai³

2006, 25(08):  954-958 . 

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In this paper, the main factors affecting the habitat selection of red-crowned crane were grouped into water body, food, shelter, and disturbance, which were classified into several classes to determine the habitat type. The survey was conducted in two seasons, i.e., migration (from mid October to late November) and wintering (from first December to late January). The sampling sites were chosen based on red-crowned crane’s living behavior, and their location was designated by GPS to ensure the uniformity of their distribution. The results showed that in migration season, the main factor affecting habitat selection was disturbance, and the optimal habitat of red-crown crane had the characters of non-disturbance, shallow water body, and low vegetation cover. In wintering season, the main factor affecting habitat selection was food, and the optimal habitat of red-crown crane had the characters of non-, light- or mid-disturbance, shallow water body, abundance of flesh-food, and low vegetation cover.

Echolocation calls of Rhinolophus ferrumequinum at its different states

SUN Keping¹; FENG Jiang¹; JIN Longru^2,3;LIU Ying¹; WU Lei¹;LI Zhenxin¹

2006, 25(08):  959-962 . 

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In this study, Rhinolophus ferrumequinum was trained in a 9 m × 4 m × 4 m net room, an Ultrasound Detector Advice was used to record its echolocation calls, and the video-recordings were synchronized with acoustic recordings. The results showed that the echolocation calls of R. ferrumequinum were of (FM/) CF/FM type. The pulse duration and interpulse interval decreased abruptly when the bat approached prey items, and the terminal FM component became more dominant. Foraging buzz was emitted at the moment of capture. There were significant differences in pulse repetition rate, dominant frequency, pulse duration, interpulse interval, and duty cycle during the bat was at flying and hanging.

Spatial pattern of tourism resources in Liaoning Province based on roads network

LI Yuehui¹;FENG Xiu²;ZHOU Rui^1,3;HU Zhibin^1,3

2006, 25(08):  963-968 . 

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The spatial relationship between tour destination and visitor source region based on roads network is an important issue in tourism geography. Employing GIS spatial analysis, this paper analyzed the spatial pattern of tourism resources and population in Liaoning Province. Based on roads network, the tourism area around big city and the service area around tourism spot, as well as the relationship between tourism resources and population were investigated. The results showed that the golden triangle and west tourism line were the hot tourism area and hot line in Liaoning Province. The former consisted of 3 main cities and three lines linking other 9 cities, and the latter mainly consisted of Panjin City and Huludao City. The central city group containing 5 cities was the main region. Both the population and the tourism had the same distribution center. The service areas containing 9 scenic resorts accounted for 92.5% of the whole Liaoning Province. The scenic resorts varied from 10 000 km² to 70 000 km², and four of them could serve more than 10 000 000 people. The numbers of the cities, total population, and population of each city in the service areas had reached certain scale, and closely related to both the city location in the roads network and the relative location to other cities.

River ecosystem service function and dam-construction

XIAO Jianhong, SHI Guoqing, MAO Chunmei, XING Zhenxiang

2006, 25(08):  969-973 . 

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River ecosystem service function implies the natural environmental conditions and their effectiveness formed and sustained by the ecological processes of river ecosystem, and includes the two aspects of products and services. In this paper, 15 kinds of river ecosystem service function, including 6 kinds of products (water supply, fish resources, inland navigation, hydro-power, recreation, and culture and aesthetics) and 9 kinds of services (flooding control, soil and sand transporting, water resources storage, soil conservancy, environmental purification, CO₂ fixation, nutrient cycling, wildlife habitat supply, and biodiversity), were introduced, and the effects of dam-construction on them were analyzed. It was suggested that keeping well-balanced river ecosystem service function would be one of the essential factors in dam-construction decision.

Affecting factors of ecosystem degradation in Xiamen Bay and significance of ecological remediation

YU Xingguang^1,2, ZHENG Senlin^2,3, LU Changyi¹

2006, 25(08):  974-977 . 

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This paper analyzed the degradation in ecological service function of Xiamen Bay, and illustrated the key affecting factors, including unreasonable sea reclamation and sea-bank construction, unsuitable coastal resources exploitation, and lagged pollution treatment works in intensively exploited coastal area. The great expenditure and difficulty of damaged ecological service function restoration suggested the great ecological function value of undamaged ecosystem, and the great economic value of harmonious development of economy with environment protection.

Research advances in microbial metabolic pathway of benzo［a］pyrene in contaminated soils

ZANG Shuyan^1,2,3;LI Peijun¹; ZHANG Ying²;WANG Juan²; XU Huaxia¹

2006, 25(08):  978-982 . 

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Benzo［a］pyrene (BaP) is one of the polycyclic aromatic hydrocarbons (PAHs) with carcinogenesis, aberrance and mutagenesis. To remedy BaPcontaminated soil, it is of significance to study the microbial metabolic pathway of BaP-degradation. In this paper, several factors affecting the process of BaP-biodegradation were introduced, including the degradation ability of different bacterium and fungus, metabolic pathway, substrates of co-metabolism, and environmental parameters. It was suggested that the accumulation and toxicity of BaP’s intermediate metabolites in contaminated soils would be an important aspect in the study of BaP-contaminated soil remediation.

Exotic plant invasion and its ecological risk assessment

MA Ye;SHEN Zhenyao

2006, 25(08):  983-988 . 

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Exotic plant invasion is an urgent global issue that threatens the sustainable development of ecosystem health. Its prevention is more effectual than treatment, and thus, the study of its ecological risk assessment could help us to prevent and reduce the invasion risk more effectively. Based on the theory of ecological risk assessment, and through the analyses of the characteristics and processes of exotic plant invasion, this paper discussed the methodologies of the ecological risk assessment of exotic plant invasion. The assessment procedure was consisted of risk source analysis, receptor analysis, exposure and hazard assessment, integral assessment, and working out of management measures. The indicator system of risk source assessment as well as the indices and formulas applied to measure the ecological loss and risk were established, and the method for comprehensively assessing the ecological risk of exotic plant invasion was worked out.

North American Waterfowl Management Plan and its enlightenment to China wetland construction

ZHANG Danju;GONG Yuanbo;LI Xianwei

2006, 25(08):  989-993 . 

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The protection of waterfowl habitat is a hotspot of wetland ecosystem research. This paper introduced the background of the North American Waterfowl Management Plan, its principles and notions, international partnerships, cost-sharing principle, and achievements made from joint venture, and analyzed the existing problems in the protection of waterfowls and their habitats in China. Some suggestions were made on taking reference of the notions of NAWMP, and on strengthening the management of our wetland reserves in light of our present situations.

Human development and environmental challenge in Zambia

Enock Sakala¹;Rodgers Mwanza²;LU Zhibo³

2006, 25(08):  994-997 . 

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With the increasing poverty of social economy and daily life, people in Zambia have to interfere with natural ecosystems for their survival. More than 60% of the population is rurally based and depends directly on natural environment, and in turn, induces environmental degradation in a large extent. Such environmental pressures include forest degradation, increasing soil cover loss and soil erosion, and large-scale climate variability with recurrent droughts. The rapid population growth and the rising consumption trend at the back drop of poor economic performance are leading to the over-harvesting of natural resources and the pollution of air, water and land. Due to the lack of data on Zambia’s ecosystems, parts of the research findings were not quantified, but the controversy between social development and environmental protection in Zambia was objectively existed.

Effects of weather condition in spring on particulates density on conifers leaves in Beijing

WANG Lei^1,2;HASI Eerdun¹; LIU Lianyou¹; GAO Shangyu¹

2006, 25(08):  998-1002 . 

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In this paper, the particulates density on the leaves of washed- and unwashed Platycladus orientalis, Sabina chinensis, Pinus tabulaeformis and Picea koraiensis in Beijing was measured within a month of spring, and was compared day by day with the weather data and the microconfiguration of test species’ leaf epidermis. The results showed that the particulates density on conifers leaves changed with the alternative appearance of rainy, windy and dusty weather in spring, and in most cases, had a lower value than in wintertime. Parts of the particulates were firmly adhered to the leaf epidermis, and could not be removed by medium intensity (15 mm) precipitation. Five or six class strong wind could not reduce the particulates density. Compared with the local dust, extraneous dust made the particulates density on leaves increased greatly. The grooves between vertebral heaves on the leaf epidermis of P. orientalis and S. chinensis could hold many small particulates deeply and firmly, making them hard to be removed by precipitation and wind. The leaf epidermis of P. tabulaeformis was smooth and sticky, and thus, had a small and easily saturated capacity of holding particulates. The particulates loosely adhered to its leaf surface were prone to be removed. The wider grooves around the stomas of P. koraiensis leaf epidermis were in favor of retaining larger size particulates, and hence, could effectively capture larger size extraneous dust.

Ecological safety assessment of grassland based on entropy－right method: A case study of Gansu pastoral area

JIA Yanhong¹; ZHAO Jun²;NAN Zhongren¹;ZHAO Chuanyan³;WANG Shengli¹

2006, 25(08):  1003-1008 . 

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Under the guidance of “pressure-state-response” model, a conceptive model of ecological safety assessment, and by the combination of entropyright and comprehensive appraisal methods, this paper made an assessment on the grassland ecological safety of Gansu pastoral area. The results of this assessment were in good correspondence to the regional actual situations, indicating that entropy-right method was applicable in this field. Using entropy-right method to determine the weights of assessment indices could resolve the problem of many indices not having unique standard, reduce the disturbance of subjectivity in the course of assessment, and reflect the contribution of each index to regional ecological safety more objectively. This method offered a new research means and idea to quantitatively assess regional ecological safety, and had certain practical value and popularization meaning in the related research fields.