Table of Content

10 November 2006, Volume 25 Issue 11

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Articles

Ecological characters of Ctenophora in East China Sea

XU Zhaoli; ZHANG Fengying; LUO Minbo

2006, 25(11):  1301-1305 . 

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Based on the investigations in four seasons from 1997 to 2000, this paper studied the seasonal quantitative variation and geographical distribution characters of Ctenophora in East China Sea (23°30′～33°00′N、118°30′～128°00′E). The results showed that the abundance of Ctenophora peaked in autumn (6.3 ind·（100 m³）^-1), followed by in spring (1.6 ind·（100 m³）^-1), winter (1.4 ind·（100 m³）^-1), and summer (0.6 ind·（100 m³）^-1) . A total of six species were observed, among which, Pleurobrachia globosa was the most important species, Hormiphora palnata and Beroe cucumis were the common species, Cestum sp. was the subordinate species, while Ocyropsis crystalline and B. avata were the rare species. The Ctenophora in East China Sea was a kind of warm water species, because its quantitative variation had a close relation with the motion of warm water current, and the key factor affecting Ctenophora abundance was warm water current but not the seasonal change of temperature. In all species of Ctenophora,P. globosa had stronger adaptability to its environment, followed by Cestum sp. and B. cucumis, and H. palnata, Ocyropsis crystalline and B. avata.

Environmental gradient analysis and species group division of tree species distribution in eastern Zhongtiao Mountain

LIU Qiufeng^1,2,3;KANG Muyi^1,3; LIU Quanru^3,4

2006, 25(11):  1306-1311 . 

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In this paper, the relationships between tree species distribution and environmental gradient in eastern Zhongtiao Mountain were studied by TWINSPAN and CCA ordination, and the species group division was made according to the relative positions of the tree species on the ordination diagram and referring to the dendrological documents. The results indicated that altitude was the most important environmental factor affecting the distribution pattern of tree species, while soil fertility and soil moisture index TRMI also played important roles. The 72 tree species (varieties) in the mountain were divided into 6 species groups, i.e., low altitude + warm and moist, low-mid altitude + warm and dry, low-mid altitude+ lukewarm and humid, mid altitude + moist + fertile soil, mid-high altitude +cool and dry + infertile soil, and high altitude + cold and humid-moist. Based on the greater similarities in the ecological features and distribution characteristics of the tree species in each group, the habitat characters of each species group were introduced in brief. The TWINSPAN results tallied well with the species group division.

Effects of nitrogen fertilization on biomass partitioning and leaf physiological characteristics of Pinus sylvestris var. mongolica seedlings on sandy soil

DENG Bin^1,2; ZENG Dehui¹

2006, 25(11):  1312-1317 . 

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Five nitrogen (NH₄NO₃) fertilization levels (g·m^-2), i.e., 0 (CK), 10.0 (N₁), 20.0 (N₂), 40.0 (N₃) and 50.0 (N₄), were employed to evaluate the effects of nitrogen fertilization on the growth and leaf physiological characteristics of Pinus sylvestris var. mongolica seedlings on sandy soil. Indexes of growth and foliar physiology were measured in May, July, and September, respectively. Nitrogen addition significantly increased plant height, relative growth rate, and biomass per plant, but not for relative water content in leaves. Obvious proline accumulation was found for N₄ level. The highest values of biomass per leaf, plant height, basal diameter, leaf mass ratio, contents of chlorophyll (a+b), chlorophyll a and chlorophyll b were found for N₃ treatment. Nitrogen addition mainly promoted the growth of P. sylvestris var. mongolica seedlings during May to July, and the N₃ level was optimum among the five levels.

Seasonal changes of leaf anti-oxidative system in Sabina and their relations to freezing tolerance

CHEN Yinping^1,2; ZHANG Manxiao³; CHEN Tuo⁴; ZHANG Youfu⁴;AN Lizhe^2,4

2006, 25(11):  1318-1322 . 

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This paper studied the seasonal changes of leaf anti-oxidative system in evergreen woody plants Sabina przewalskii and S. chinensis during their adaptation process of freezing. The results showed that the freezing tolerance of Sabina was correlated with its leaf anti-oxidative system whichcould scavenge or detoxify reactive oxygen species (ROS), inhibit membrane lipid peroxidation, and maintain membrane integrality in time. The ROS accumulated in the process of cold acclimation might induce the leaf to acquire freezing tolerance through its anti-oxidative system. The better capability of anti-oxidative system in S. przewalskii might account for its greater freezing tolerance than S. chinensis.

Niche of main plant populations on a warm-seasonal pastureland of alpine Kobrecia parva meadow

DONG Quanmin^1,2;ZHAO Xinquan¹; MA Yushou²; LI Qingyun²; SHI Jianjun²; WANG Yanlong²; SHENG Li¹; YAN Mingyi²

2006, 25(11):  1323-1327 . 

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The study on the dominance, niche breadth and niche overlap of twenty main plant populations on a warm-seasonal pastureland of alpine Kobrecia parvameadow under four grazing intensities showed that after two years grazing,K. parva and Elymus natans were the dominated plants in the control, light grazing, and moderate grazing plots, while Potentilla anserine and Pedicularis alaschanica dominated in heavy grazing plot. Because of their high endurancein grazing, drought, and tramping, K. parva, K. humilis and K. capillifolia had awide niche breadth, with the values being 0.938, 0.824 and 0.815, respectively. The niche breadth of E. natans was relatively narrow (0.805) owing to its bad biological characters in enduring grazing, drought and tramping. The niche breadths of D. kokonorica, Stipa aliena, S. purpurea, Festuca rubra and Ptilagrostis dichotoma based on grazing gradients were all very narrow, with the values being 0.226, 0.448, 0.445, 0.608 and 0.605, respectively, indicating that grazing restricted the growth of high grasses and created a good environment for the growth of short sedges. The niche overlaps between S. aliena and S. purpurea, and P. kansuensis and P. alaschanica were relatively narrow (0.500, 0.572), which could be seen as the results of resource utilization differentiation between plant species. The species with grater niche breadth generally had greater niche overlap with other species, while the species distributed on the two extremeness of the grazing gradient had narrower niche overlap with each other, suggesting that the distribution of the species was both continuous and discontinuous.

Recent thirty years evolvement trend of Calamagrostis angustifolia community in Sanjiang Plain

JI Yuhe^1,2; LV Xianguo²; YANG Qing²;ZHAO Kuiyi²

2006, 25(11):  1328-1332 . 

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With the change of habitat, there was a notable change in the Calamagrostis angustifolia community, a typical plant community in swamp wetland of Sanjiang Plain. Based on the localized observation data and field survey in typical wetland, this paper analyzed the recent thirty years evolvement trend of C. angustifolia community in the Plain. The results showed that the species frequencies of C. angustifolia community accorded with Raunkiaer frequency law, which was in the order of A＞B＞C≥D＜E. The species in C. angustifoliacommunity altered obviously, among which, shrub plants increased gradually, resulting in a reduced diversity of plant species. The abundance, div-coverageand height of C. angustifolia all presented a descending trend.

Effects of exogenous spermidine on anti-oxidative enzyme activities in cucumber seedlings under salt stress

ZHANG Runhua;GUO Shirong;FAN Huaifu; LI Juan

2006, 25(11):  1333-1337 . 

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In a hydroponic experiment with the seedlings of cucumber varieties “Changchun Mici" (salt-tolerant) and “Jingchun No. 2" (salt-sensitive), this paper studied the effects of exogenous spermidine (Spd) on the O₂^-. producing rate and protective enzyme activities in roots and leaves under NaCl stress. The results showed that exogenous Spd had no significant effects on the O₂^-. producing rate and the activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT) in the control, but further increased the activities of SOD, POD and CAT while decreased the O₂^-. producing rate under salt stress, indicating that exogenous Spd could alleviate the salt stress damage on cucumber seedlings. Comparing with “Jingchun No. 2", the cucumber variety “Changchun Mici" was less affected by saltstress, and the alleviation effect of exogenous Spd on salt stress damage was less in “Changchun Mici" than that “in Jinchun No. 2".

Niche of epiphytic bryophytes on trees in Shanghai City

XU Shengchong;CAO Tong;YU Jing;CHEN Yi; SONG Guoyuan

2006, 25(11):  1338-1343 . 

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Niche theory is valuable in plant ecology, but not introduced in the research of epiphytic bryophytes on trees. In this paper, 18 sampling sites at the main parks, streets, and campuses in Shanghai City were selected, and the epiphytic bryophytes on ten trees in sixteen 20 cm×20 cm quadrats of each site were sampled at 4 heights above the base of tree trunk and 4 exposures. 43 species of epiphytic bryophytes including 39 mosses and 4 liverworts were recorded. The niche breadth of the 43 species calculated by Levin’s equation based on their coverage showed that the relationship between species number (N) and niche breadth (B) followed N=0.3423 e^-0.0369B, r=0.9347. Most epiphytic bryophytes had rather narrow niche breadth, and 67.44% of them had a niche breadth less than 0.1, suggesting that in the protection of bryophytes, more attention should be paid on the protection of epiphytic bryophytes on trees and of their special habitats. The niche overlaps of the 43 epiphytic bryophytes species were calculated by Wang’s equation, and the ordination plot of Principal Component Analysis (PCA) and the Minimal Spanning Tree (MST) were drawn. The results showed that these 43 epiphytic bryophytes species could be classified into three ecological groups,which had significant correlations with habitats.

Lead tolerance of different Fagopyrum esculentum cultivars

LIU Yonghai; YU Le; CHEN Yibin;LIU Xihui;WU Lei;HUANG Jingshang;HE Suping

2006, 25(11):  1344-1347 . 

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This paper studied the difference of three Fagopyrum esculentum cultivars in lead tolerance after treated their seedlings with different concentrations Pb²⁺ for seven days. The results showed that low concentration Pb²⁺ had definite stimulation effect on root growth, while high concentrations Pb²⁺ was in adverse.The inhibition of root growth under high concentrations Pb²⁺ was differed with cultivars,i.e., Xiqiao No.1 was most serious, followed by Jinqiao No.1, and Jiujiangkuqiao. Under 1 500 μmol Pb²⁺·L^-1, the relative cytoplasm membrane permeability of the three cultivars increased, but their chlorophyll and protein contents decreased to various degree. The increment or decrement was the largest in Xiqiao No.1 and the smallest in Jiujiangkuqiao. All of these suggested that among the three cultivars, Jiujiangkuqiao was the strongest in lead tolerance,while Xiqiao No.1 was the weakest.

Effects of transgenic cotton planting on soil hydrolase activity

ZHANG Lili¹; WU Zhijie¹; CHEN Lijun¹; SUN Caixia²

2006, 25(11):  1348-1351 . 

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With the increasing area of transgenic Bt and Bt+CpTI cottons planting, it's of significance to assess the environmental risk of their toxins release. In this paper, a pot experiment with transgenic Bt cotton"Zhong 30" and Bt+CpTI cottons “Zhong 41" and “Shuangkang 321" was conducted to study the persistence characteristics of their toxins in soil and the effects of these toxins on soil hydrolase activity. The results showed that Bt toxin was introduced into soil after 30 days of seedlings growth, and the introduced amount of CpTI toxin was differed with the cultivars. Compared with the relevant non-transgenic cottons, the planting of“Zhong 30" and “Zhong 41" had nosignificant effects on the activities of soil urease, proteinase and phosphomonoesterase, while that of “Shuangkang 321" decreased soil phosphomonoesterse activity significantly. From the viewpoints of toxin release and its effects on soil hydrolase activity, the planting of "Zhong 41"caused fewer disturbances on soil biological activities.

Effects of simulated acid rain on form transformation and environmental behaviors of heavy metals in amended sludge compost

HUANG You;CHEN Ling;LI Yuqing;ZHU Zhiliang;ZHAO Jianfu

2006, 25(11):  1352-1357 . 

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In a simulation experiment with saline soil column, this paper studied the effects of acid rain (pH=5.0 and 2.9) on the mobility and form transformation of Zn, Cu and Ni in amended sludge compost. The leachate was collected every other day over 42-day experiment, and the heavy metals in soil were fractionated by using sequential extraction method. The results showed that under the same acid rain intensity, the heavy metals content in leachate and their migration in soil followed the sequence of Zn>Cu>Ni, and the heavy metals content in the same soil depths was in the order of Zn> Ni > Cu. The decrease of acid rain pH and the increase of sludge compost dosage increased the heavy metals content in leachate and soil, but had no effect on their migration. Soil acidification promoted the transformation of heavy metals to activated forms and their migration to deeper soil.

Dynamics of patch size structure in landscape fragmentation process in Nanjing urban district

ZHANG Mingjuan¹; LIU Maosong²; XU Chi²; WANG Lei³

2006, 25(11):  1358-1363 . 

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Based on three scenes of TM imagery in 1988, 1998 and 2003, the patch size area of the farmland, forestland, resident area, and constructing area in Nanjing urban district was classified into sixteen levels, and the quantitative variation of different level patches in the process of landscape fragmentation was studied. The results showed that farmland displayed diminished area and increased fragmentation degree, with the number of small-to-medium sized patches increased steadily. Forestland had a little fluctuation in its total area, with a stable amount of medium-to-large sized patches but a greatly variednumber of small-to-medium sized patches. Resident area expanded muchbased on the existed patches from 1988 to 1998, but new patches mushroomed from 1998 to 2003. Constructing area developed rapidly, and its land use scale enlarged. All of these indicated that both the type and size of patch had definite effects on the patch stability and its change trend.

Population characteristics in upper reaches of Minjiang River

HU Zhibin¹; HE Xingyuan¹; LI Yuehui¹; BU Rencang¹;WANG Anpeng^1,2

2006, 25(11):  1364-1369 . 

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By using the population and economic data extracted from the statistical yearbook of 1986-2003 and the data from national GIS database (1∶250 000), an ArcGIS-based spatial population database of five counties in theupper reaches of Min River was built, and the spatial population distributionand its affecting factors were studied by the combination of traditional statistics and GIS analysis. The results showed that the dominant minorities in the study area were Tibetan, Qiang and Han, with Smau Paewation size and thin density of population (0.38 4 million and 16.94 people·km^-2 in 2003, respectively) and low growth rate. The spatial distribution of population tended to imbalance, and the redistribution index declined obviously. In the past 50 years, the center of papulation moved 6.30 km from north to south, indicating that the economy in the south area developed in good status. The spatial distribution of population was mainly affected by the distribution of rivers and roads, elevation, types of LUCC, and economic attraction.

Microbial quantity and enzyme activity in Fargesia denudata rhizosphere soil of western Sichuan

QI Zemin¹; YANG Wanqin²

2006, 25(11):  1370-1374 . 

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The study showed that in the Fargesia denudata rhizosphere soil of western Sichuan, the quantity of bacteria and fungi was obviously higher than that in non-rhizosphere soil, while no significant difference was observed for actinomyces, with the average R/S values being 2.36, 2.08 and 1.08, respectively. The activities of acid phosphatases, proteinase, urease, invertase, catalase and polyphenol oxidase in rhizosphere soil were significantly higher than those in non-rhizosphere soil, and their average R/Svalues were respectively 1.48, 1.57, 2.14, 1.37, 1.98 and 1.67. For the F. denudata stands with different ages, the quantity of bacteria and fungi and the activities of test enzymes in rhizosphere soil were in the order of 3-, 5-and 7-year-old stand > 9-, 11-and 13-year-old stand > 1-year-old stand, butno distinct difference was found in the quantity of actinomyces.

Grassland insect community diversity in Tibetan region of northwestern Yunnan under different management patterns

LI Qing^1,2; WU Zhaolu¹;LIU Lingling^1,2; XU Ning^1,2; YANG Xiaodong¹

2006, 25(11):  1375-1379 . 

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The study with field sampling method showed that in the Tibetan region of North westeon yunnan Province, the dominant groups of grassland insect community were Cicadelloidea, Miridae, Muscidae and Cecidomyiidae. The number of insect families on forage grassland, cultivated grassland, grazing grassland and shrub grassland were 40, 44, 35 and 36, and that of insect individuals were 1869, 1510, 997 and 848, respectively, indicating the higher richness and abundance of insect community on forage-and cultivatedgrasslands. The biodiversity index of cultivated grassland was also the highest. Based on the criterion of Jaccard’s ISJ, a medium similarity of insectcommunity was observed on the four grasslands. Different management patterns of grassland had definite effects on grassland insect community diversity, and traditionally managed forage grassland was benefited to the maintenance of this diversity.

Effects of Aphis fabae instars on Lysiphlebus ambiguus parasitism and its offspring fitness

CAO Lin;LI Baoping

2006, 25(11):  1380-1383 . 

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Host size models assumed that the host quality for parasitoid growth and development is a linear function of host size. To test this assumption, a single-coice experiment was conducted to study the parasitism and offspring fitness performances of Lysiphlebus ambiguus developed on different nymphal instars of black bean aphis Aphis fabae. The results showed that all host instars and adults were susceptible to parasitism, but L₂ was most favored (35.25%) while adults were least attacked (14.75%). The eclosion rate of offspring wasps was significantly higher in young nymphs than in older hosts. The development duration of offspring was the shortest in L₂ (8.4 d) and the longest in adults (9.3 d), while the body size of offspring was greater in L₂-L₄ than in L₁ and adult. The female proportion in offspring wasps was significantly greater in L₄ (75.74%) than in L₁ (62.89%) and adult (65.19%), but not statistically different from that in L₂ and L₃ hosts. Based on the fitness returns to the females of parasitoid, the quality of the host aphid varied in the order of L₂>L₃=L₄>adult>L₁, indicating that host quality was not a linear function of host size for the parasitization in L. ambiguus-A. fabae system.

Coral reef ecosystem service and its value evaluation

WANG Lirong^1,2; ZHAO Huanting^1,2

2006, 25(11):  1384-1389 . 

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Coral reef ecosystem is overused for its high biodiversity and beautiful underwater landscape. To evaluate its service value is very important in the effective management and sustainable use of the ecosystem. This paper reviewed the research advances in coral reef ecosystem service and its value as well as relevant evaluation methods. The value types associated with coral reef ecosystem service and the 5 commonly used evaluation methods were introduced, and the distribution and characteristics of coral reef in China were summarized. According to the present situation of the coral reef ecosystem in China, the significance of developing the researches on coral reef ecosystem service and its value evaluation was discussed.

Research advances in affecting factors and prevention techniques of soil wind erosion

MA Yuecun;CHEN Yuanquan;SUI Peng; YIN Chunmei

2006, 25(11):  1390-1394 . 

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Soil wind erosion is an important factor which limits the world agricultural sustainable development and environmental quality. This paper introduced the main affecting factors of soil wind erosion, and its main prevention techniques commonly used nowadays. Through the comparison of the advantages and disadvantages of these techniques, it was considered that the most feasible approach is to implement conservation tillage, with other techniques as supplement. By the end of this paper, the reasons of the slow evolvement in preventing soil wind erosion were analyzed, and some constructive suggestions were put forward.

Nutrient internal cycling in tree fine root: A review

HUANG Shizhu; ZHANG Yandong;WANG Zhengquan

2006, 25(11):  1395-1399 . 

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Nutrient internal cycling plays an important role in reducing the nutrient loss while enhancing its use efficiency by trees. The fine root of trees is short in life but fast in turnover, and thus, the research of nutrient internal cycling in tree fine root has being recognized in recent two decades. This paper discussed the significance of nutrient internal cycling in tree fine root, introduced the current situations of its research at home and abroad, and prospected its research trend in the future.

Myxospermy and its ecological function

MA Junling^1,2;LIU Zhimin¹

2006, 25(11):  1400-1404 . 

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Myxospermy is commonly existed in the plant families Brassicaceae, Acanthaceae and Asteraceae in arid regions. This paper summarized the concept of myxospermy, characters of mucilage, and present situation and issues in myxospermy research. At present, the studies of myxospermy are focused on the identification of mucilaginous species, the structure and component of mucilage, the mechanisms and processes of mucilage production, and the functions of myxospermy. In the future,the ecological functions of myxospermy should be more concerned, especially from the aspect of identifying the mucilaginous species in different flora. New methodologies should be introduced, and the significance of myxospermy in vegetation restoration should be further explored.

Factors affecting litter decomposition of wetland herbaceous macrophytes

WU Haitao^1,2;Lü Xianguo^1,2; YANG Qing¹

2006, 25(11):  1405-1411 . 

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Herbaceous macrophyte is a main vegetation type on wetland. Its litter decomposition is one of the key processes in the material cycling and energy flow of wetland ecosystem, and plays an important role in maintaining the functions of the ecosystem. This paper reviewed the research progress on the main factors affecting the litter decomposition of wetland herbaceous macrophytes, including the quality of litter itself, biotic and abiotic factors, and human activities, etc., and discussed the issues to be further studied. More attention should be paid on the mechanisms of litter decomposition, the effects of global climate change on the decomposition, and the approaches of related integrative and multi-scale research.

A research review on soil active organic carbon

LIU Min;YU Wantai;JIANG Zishao;MA Qiang

2006, 25(11):  1412-1417 . 

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Soil active organic carbon is the most important carbon pool in soil, due to its active characters and fast turnover. It has great significance in the study of soil carbon cycling and carbon interception, and is a good indicator in ecosystem management. Generally, it originates from litter decomposition, plant root secretion, soil organic matter hydrolysis, microbes themselves and their metabolic products, and is affected by season, humidity, land use/ land management pattern , and soil pH, etc. It greatly affects the solution, adsorption, desorption, translocation, and biotoxicity of soil chemical substances, and thus, has strong influences on soil nutrients flux, heavy metals mobility, metal complexes formation, and inherent productivity. In addition, the content of this carbon directly affects the quantity and activity of soil microbes, and accordingly, affects the greenhouse gases emission and its regulation, the quality of aquatic ecosystem, and the erosion process of lithosphere. To further study the dynamics of soil active organic carbon is of significance for environmental protection and nutrients cycling.

Global climate change and mangrove

LIU Xiaowei; ZHENG Wenjiao; SUN Juan

2006, 25(11):  1418-1420 . 

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Mangrove locates at the interface between land and sea, and is likely to be one of the first ecosystems to be affected by global climate change. Its distribution area would be enlarged with raising temperature. The most important effects of global climate change on it would be the rising sea levels. Most mangroves will benefit from increased CO₂ via higher photosynthetic rate, water use efficiency, and growth rate. At relatively low light level, the photosynthetic rate of mangroves tends to increase. The strategies to deal with these changes were put forward.

Deoxyschizandrin and schisandrin B contents of Schisandra chinesis fruit from different origins

LIU Guifeng; NIU Yuda;YANG Chuanping; YU Ying;HOU Yingjie;WANG Yang

2006, 25(11):  1421-1424 . 

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To provide valuable reference for selecting optimal origin of Chinese herbal medicine, Schisandra chinensis fruits were collected from 16 origins, and theirdeoxyschizandrin and schisandrin B contents were analyzed by HPLC. The results indicated that there exited significant differences in deoxyschizandrin and schisandrin B contents among different origins, with the highest contents being 2.14 and 3.3 times as high as those of the lowest, respectively. The deoxyschizandrin content had a significant positive correlation with temperature and humidity, while schisandrin B content didn't. The Weihe County in Heilongjiang Province and Liuhe County in Jilin Province were tentatively selected as the optimal origins of S. chinensis fruit based on thecontents of main medicaments.

Cadmium absorption characteristics of Zea mays under combined stress of lead and cadmium

CAO Ying;HUANG Ruidong;LI Jiandong; ZHAO Tianhong;GUO Wei;WANG Guojiao

2006, 25(11):  1425-1427 . 

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A pot experiment with maize variety Fuyou 1 showed that under the combined stress of lead and cadmium, the accumulation of cadmium in different parts of plant and at different development stages was in the order of root>down-leaf>stem>up-leaf>grain and of jointing stage>flowering stage>ripening stage. The cadmium content in plant was generally higher under combined stress than under single cadmium stress, but increased first while decreased when the lead content in soil increased from 0 to 540 mg·kg^-1.

Pasture production and its spatio-temporal distribution pattern in Qinghai Province: An estimation with remote sensing

HOU Yingyu^1，2;MAO Liuxi²; QIAN Shuan²; FU Yang³

2006, 25(11):  1428-1434 . 

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Based on the Normalized Difference Vegetation Index (NDVI) and the actual observation data, the pasture production estimation models for different types of grassland in Qinghai Province were established and validated. The results showed that all the models had high precision, and the correlation coefficients (R²) obtained from all regression equations were higher than 0.67, indicating that the models could be used to estimate the pasture production in a large area at a near-real time. By using the established models, the monthly pasture production on a cell scale in the province from May to August 2004 was retrieved. Based on the images of pasture production distribution retrieved in different periods, the temporal-spatial distribution pattern of pasture production was analyzed, and the results indicated that in Qinghai Province, the temporal distribution of pasture production was mainly determined by the pasture growth cycle and climate change, while the spatial distribution was related to the grassland type and its climatic attributes.

Evaluation of regional ecotourism suitability based on GIS and artificial neural network model: A case study of Zhejiang Province, China

ZHENG Xiaoxing;SUN Ming;CHEN Ying;WANG Xiangrong

2006, 25(11):  1435-1441 . 

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As the link point of regional resource theory and tourism exploitation activity,the evaluation of regional ecotourism suitability plays a significant role in the regional industrial allocation and macroscopic control, but few researches have been done in this field. Based on the concept of regional ecotourism suitability, the evaluation indices system of regional ecotourism suitability was compos ed from the aspects of tourism resources, eco-environmental quality, and social-economical conditions, and by means of the spatial analysis of GIS and the self organization feature map in artificial neural network model, a cluster analysis was performed to assess the regional differentiation of ecotourism suitability in the 72 counties of Zhejiang Province. According to the results of cluster analysis, the study areas were divided into five types of regions,i.e, most suitable, highly suitable, medially suitable, generally suitable, and key construction regions. The ecotourism suitability of these regions was evaluated, and the countermeasures for regional sustainable development were put forward, which had consultation meaning to probe into the orientation and development strategy for regional tourism industry.

Three methods of niche analysis on mollusk in mangrove area

TANG Yijie^1,2; YU Shixiao¹; KE Zhijun²

2006, 25(11):  1442-1448 . 

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Based on the mollusk density data from quantitative sampling, and choosing tidal flat and season (method 1), mangrove and season (method 2), and mangrove and tidal flat (method 3) as the combinations of environmental factors to decide the spot number of environmental resources, this paper calculated the niche breadth and niche overlap of mollusk species in Zhanjiang Mangrove Nature Reserve by using Shannon-Wiener and Pianka formula. The results showed that the niche breadth of the mollusk species calculated by the methods 1, 2 and 3 was 0-1.96, 0-2.16 and 0-1.64, and the niche overlap at 0-0.1, 0.1-0.5 and > 0.5 among the species accounted for 25.1%, 32.8% and 21.6%, 31.6%, 362% and 223%, and 43.3%, 31% and 56.1%, respectively, suggesting that the niche overlap calculated by method 3 was bigger than that by other two methods. The hierarchical cluster dendrogram and MDS ordinal configuration of mollusk species also verified the difference of the three methods. Comparing the calculated results with actual quantitative sampling data, the analysis method of using mangrove and season to decide the spot number of environmental resources was in accordance with the reality, which was feasible for the niche study of mollusk in mangrove area.