Table of Content

10 February 2007, Volume 26 Issue 02

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Articles

Characters of vascular plant communities in natural wetlands of Nanjing Suburb

ZHANG Guang-fu;CHEN Hui-yan;CHEN Rui-bing;GAO Bang-quan

2007, 26(02):  145-150 . 

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By applying GPS orientation, field specimen collection and Braun-Blanquet Cover Abundance Scale Method, the plant species composition, community type, species diversity index, ecological dominance index, and community evenness index in two wetlands of Nanjing suburb were studied, and the results showed that there were 104 species of vascular plant, belonging to 93 genera and 45 families, among which, Ceratopteris thalictroides, Glycine soja, Trapa incisa and Nelumbo nucifera were the grade Ⅱ rare and endangered plants protected by national law. Geographic element analysis of both genera and species demonstrated that temperate elements took dominant position, and tropic elements occupied definite proportion. The vegetations were classified into 3 vegetation types, 3 sub-vegetation types and 16 formations. The species diversity in the natural wetlands of Nanjing suburb was relatively low, being higher in Qilihe wetland than in that at the mouth of Chuhe. Countermeasures were put forward for the biodiversity protection of vascular plant communities in the natural wetlands of Nanjing suburb, based on the analysis of the characters of the plant communities and the existing problems.

Ecological characteristics of typical plant communities in Kunyu Mountain

DU Ning¹; WANG Qi²; GUO Wei-hua¹; WANG Ren-qing¹

2007, 26(02):  151-158 . 

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The investigation on the ecological characteristics of natural and artificial plant communities in Kunyu Mountain showed that the species number, species dominance, and dominant species in both shrub and herbage layers differed with vegetation type. There was a strong correlation among the indices characterizing the community ecological characteristics, of which, Shannon-Wiener (H) index had the closest correlation to others. The comparison of the species diversity in different layers with H value as an indicator indicated that the relations between the species diversity of shrub and herbage layers varied with vegetation type, but the average H value tended to be stable, suggesting that there was an inter-complementary relationship between the shrub and herbage layers species diversity. Owing to the heterogeneity of the environment, different communities belonging to the same vegetation type always had different species diversity. The species diversity of shrub layer and herbage layer was in the order of shaw>P. densiflora forest>P. thunbergii forest>Quercus acutissima forest when the plant communities were natural or less managed, but P. thunbergii forest>P. densiflora forest>shaw>Q. acutissima forest after the P. densiflora and P. thunbergii forests were managed. The growth of arbor layer was inhibited in P. thunbergii and P. densiflora forests, which was in accordance with the theory of “moderate disturbance”. In general, the management of P. densiflora forest achieved moderate disturbance level, while that of P. thunbergii forest was excessive.

Age structure of Cinnamomum burmannii population on Karst hills of Guilin

ZHANG Zhong-hua¹; HU Gang¹; LIANG Shi-chu¹; WU Shu-jie^1,2; WANG Li-jun¹; LI Feng¹

2007, 26(02):  159-164 . 

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In this paper, age structure, the relationship between the age and the stem diameter of Cinnamomum burmannii populaion were studiedl survival curve and age structure pictures were given.This results showed that on the Karst hills of Guilin, there was a linear relationship between the age and the stem diameter of C. burmannii population. Young-aged individuals were more, while middle-aged and old individuals were less. The age structure was classified into two types, growing and stable, while the survival curve was of types Deevey Ⅲ and Ⅱ. Habitat condition and human disturbance were the main factors affecting the age structure and the dynamics of C. burmannii population, and thus, the protection and fostering of C. burmannii community should be reinforced, meanwhile the human disturbance should be reduced.

Succession and distribution pattern of vegetation communities on Jiuduansha Wetland

SHI Wen-yu; GE Zhen-ming; WANG Tian-hou; ZHOU Xiao; ZHOU Li-chen

2007, 26(02):  165-170 . 

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Jiuduansha Wetland is a newly formed intertidal wetland, which consists of three parts, i . e ., Shangsha, Zhongsha and Xiasha. The study on the succession and distribution pattern of vegetation communities on this wetland in 2004 showed that the dominant species were Phragmites australis, Spartina alterniflora, Scirpus mariqueter, and Scirpus triqueter. P. australis and S. alterniflora dominated the areas in high tidal flat, while S. mariquete and S.triqueter occupied the inter-middle tidal flat. The area covered by the vegetations was increased by an average of 17%, 22% and 38%-39% per year in Shangsha, Zhongsha and Xiasha, respectively, and the vegetation communities were in accelerated succession, which might be correlated with the development of the wetland. Due to artificial planting, the area covered by S. alterniflora community in Zhongsha and Xiasha increased from less than 1% in 1998 up to 22% of the whole vegetation area in 2004, and the annual increase of the total aboveground biomass of S. alterniflora was 79.79%. The competition pressure of S. alterniflora on S. mariqueter and S. triqueter was heavy. Some elementary measures on the management of the vegetation communities on Jiuduansha wetland were brought forward.

RAPD analysis on the genetic differentiation of Dicranopteris pedata population exposed to heavy metals pollution

LI Jun-min¹; JIN Ze-xin¹; ZHU Hui-ci²; KE Shi-sheng¹

2007, 26(02):  171-176 . 

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By using random amplified polymorphic DNA (RAPD) technique, this paper analyzed the genetic diversity and differentiation of Dicranopteris pedata populations in the habitats with and without mine tailings Pb-Zn pollution. A total of 102 polymorphic loci were detected from 170 loci, and two RAPD-marked loci of the D. pedata population exposed to 20 years mine tailings Pb-Zn pollution were lost, which were presumed to be the gene segments sensitive to heavy metals. The population under mine tailings Pb-Zn pollution had slightly lower percentage of polymorphic loci, Shannon’s information index, and Nei gene diversity than un-polluted one (52.94%, 0.3059 and 0.2084；53.53%, 0.3196 and 0.2198, respectively), but its total genetic diversity was relatively high (70.59%, 0.3723 and 0.2472, respectively). There was a definite genetic differentiation between these two populations (Φ_st=0.1900, and G_st=0.1339), but the variation degree between the populations was far less than that within the populations, and the gene flow between the populations was high. Pb-Zn pollution had a deeper influence on the genetic differentiation of D. pedata, suggesting that this pollution might be a main driving force in the differentiation and micro-evolution of D. pedata in the process of adapting heavy metals pollution.

Blossom character and insect pollination of Prunus mongolica Maxim

FANG Hai-tao¹;Seqinbate²

2007, 26(02):  177-181 . 

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A two-year investigation on the blossom character and insect pollination of endangered plant Prunus mongolica Maxim showed that the role of wind-pollination could be neglected because the wind-diffused pollen of P. mongolica decreased rapidly with increasing distance. The nectar and the smell of P. mongolica blossom played a main role in inducing insect pollination. A total of seventeen kinds of insects including bees, flies and butterflies were observed as the pollinators, whose visiting frequency had a close relation to the characters of blooming. These insect pollinators preferred to visit the blossom in its flourishing anthesis. P. mongolica tended to be cross-pollinated by insects, but lacked of faithful pollinators.

Plant species diversity of alpine grasslands on southern slope of Tianshan Mountain along altitude gradient

HU Yu-kun¹; LI Kai-hui^1,2; Adeli Maidy¹; LIU Yan-yan^1,2; FAN Yong-gang^1,2; WANG Xin^1,2; GAO Guo-gang^1,2

2007, 26(02):  182-186 . 

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Climate alteration due to altitude gradient makes mountain biota a hotspot of biological richness research. The study on the plant species diversity of Bayanbulak alpine grasslands on the southern slope of Tianshan Mountain showed that at 9 sampling sites along altitude gradient, a total of 34 species was recorded, belonging to 29 genera and 17 families. The species richness along altitude gradient presented partially unimodal pattern, being the maximal on the Alchemilla tianschanica grassland at 3 060 m, with 17 species belonging to 12 families and 17 genera. The Shannon-Wiener index also showed a partially unimodal pattern. Its variation range was 2.02-2.40, with the maximum on the A. tianschanica grassland at 3 060 m and the minimum on the Stipa purpurea grassland at 2 760 m. The Cody index along altitude gradient presented unimodal pattern. Shannon-Wiener index was negatively correlated with the temperature, while positively correlated with the relative humidity and soil moisture content in growing season.

Nitrogen metabolism of transgenic Bt cotton and transgenic Bt-CpTI cotton at seedling stage

SUN Cai-xia¹;ZHANG Li-li²;WU Qiong³;MIAO Lu¹;WANG Gou-wei¹;LI Shao-ji¹

2007, 26(02):  187-191 . 

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Nitrogen metabolism of Bt transgenic cotton and Bt-CpTI transgenic cotton at seedling stage was studied by pot experiment. The results showed that the characters of nitrogen metabolism in transgenic cotton leaves changed and differed in different transgenic events. In comparing with non-transgenic treatment,there were not significant differences in the activities of nitrate reductase and peptidase and in the content of free amino acid, but there was a significant increase in GTP activity and a significant decrease in free amino acid in transgenic Bt cotton leaves. Except for the soluble protein content, all the other characteristics of nitrogen metabolism of Bt-CpTI transgenic cotton Z41 changed significantly. Both the peptidase activity and the soluble protein content in Bt-CpTI transgenic cotton SK321 increased significantly, but the activities of nitrate reductase and GTP and the content of free amino acid in that treatment didn’t change obviously. The unantichipated effects of transgenic crops would be more uncertain and complex along with diversification of transgenic genes.

Effects of different soil moisture conditions on the growth and yield of Zizyphus mauritiana Lam. in dry and hot valley of Jinsha River

XUE Pei-pei¹; WANG Ke-qin¹; GUO Feng-chun²; LUO Gui-yun²

2007, 26(02):  192-196 . 

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This paper studied the height growth, basal diameter growth, new branch growth, branch diameter growth, leaf area, leaf area index, fruit setting rate, yield per plant, leaf water content, and root water content of 3 years old Zizyphus mauritiana Lam. in the dry and hot valley of Jinsha River under 4 levels of soil moisture content. Principal component analysis (PCA) and R-factor analysis were made to determine the optimal soil moisture condition for Z. mauritiana growth. The results showed that 70%-85% of field capacity was most appropriate, with a compositor value responding to soil moisture being 56.147, followed by 85%-100% and 40%-55% of field capacity, with the compositor value being 41.506 and 34.545, respectively. It was suggested that 70%-85% of field capacity was the most suitable soil moisture content for Z. mauritiana in the dry and hot valley of Jinsha River.

Spatial heterogeneity of soil properties in Jianfengling Nature Reserve

WEI Yan-chang^1,2; OUYANG Zhi-yun¹; MIAO Hong¹; WANG Xiao-ke¹; ZHEN Hua¹; JIANG Li-jun¹

2007, 26(02):  197-203 . 

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In this paper, horizontal and vertical strips including ten types of ecosystems in Jian-fengling Nature Reserve of Hainan Island were chosen to study the spatial heterogeneity of soil properties in this region. The results showed that on horizontal strip, the organic carbon, total ni-trogen and available nitrogen contents in 0-20 cm soil layer ranked in the order of tropical mountain rain forest＞natural secondary forest＞Caribbean pine, Chinese fir and tea-oil camellia plantations. On vertical strip, the contents of organic carbon, total nitrogen and total phosphorus in 0-20 cm soil layer were the highest in tropical mountain rain forest, and had a decreasing trend towards higher and lower altitudes, with significant difference between test ecosystems. Soil available nitrogen,available phosphorus, and cation exchange capacity had different variation se-quences with other soil properties, but significantly correlated with soil pH. The tropical mountain rain forest located at mid-high altitude with slight anthropogenic disturbance had the highest soil nutrient-holding capacity and integrated soil quality index. Among the disturbed forest types, natural secondary forest had the best integrated soil quality index. At altitude gradient, tropical evergreen monsoon forest was the most vulnerable and sensitive forest type. Soil quality mainte-nance would be of significance in protecting tropical original forest and promoting its natural resto-ration after destroyed.

Evaluation of waterlogging and drought tolerance of three Ilex species

LI Shu-qin¹; ZHANG Lu²; ZHANG Ji-lin¹； HAO Ri-ming²；JIAO Zhong-yi¹; DONG Yi-bo¹

2007, 26(02):  204-208 . 

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This paper studied the eco-physiological responses of three Ilex species to waterlog-ging- and drought stress. Waterlogging tolerance experiment showed that the contents of proline and MDA in test species increased, while net photosynthetic rate decreased with increasing dura-tion of waterlogging. The responses came earlier by Ilex viridis, followed by I. chinensis, and I. cornata var. fortunei.I. viridis could endure waterlogging for one week, while I. cornata var. fortunei could endure this stress for two weeks or longer. All the three species could be planted in the south of Yangtze River without any limitation of waterlogging. Drought tolerance experiment showed that the proline content in test species increased with increasing duration of drought,and I. viridis had the peak value earlier than I. chinensis and I. cornata var. fortunei. I. viridis could endure drought for 15 days, while I. cornata var. fortunei could endure it for 25 days. All the test species could endure water stress to some degree, I. cornata var. fortunei being the strongest, followed by I. chinensis, and I. viridis.

Potential variability of trans-lysozyme gene rice under ecological conditions of Yunnan

YAO Chun-xin¹; XU Ming-hui¹; TIAN Wen-zhong²; TANG Zuo-shun²

2007, 26(02):  209-212 . 

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With trans-lysozyme gene rice line D2-1-2 and its restorer Zhonghua No.9 as test materials, this paper studied their agronomic characters and grain qualities under two ecological conditions of Yunnan. The results showed that there were no significant differences in the agronomic characters between D2-1-2 and Zhonghua No.9, but the seed setting rate and plant height of D2-1-2 were significantly lower, while the protein, amino acid, and mineral element (Ca, Fe and Zn in particular) contents in its crude grain were higher than those of Zhonghua No. 9. It was considered that there could be some potential genetic variances in transgenic plant, and the possibly induced environment risk should be evaluated in multiplots for several years.

Winter bed-site selection of Capreolus capreolus in low mountain areas of southern Xiaoxing’anling Mountains

TENG Li-wei¹; LIU Zhen-sheng^1,2; ZHANG En-di¹; MA Jian-zhang²

2007, 26(02):  213-218 . 

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This paper studied the selection of winter bed-sites by Capreolus capreolus in the low mountain areas of southern Xiaoxing’anling Mountains, Northeast China. Both Jocabs’ and resources selection functions revealed that C. capreolus preferred the coniferous and broad-leaved mixed forest on sunny slope, referring with shrub height, ground cover and snow depth in day-time, and the coniferous and broad-leaved mixed forest and broad-leaved mixed forest on shady slope, considering arbor crown breadth and ground cover in nighttime. There were significant differences in the vegetation type, slope direction, crown breadth, shrub height, ground covers of <1 m and 1-2.5 m, hiding degree, and length and width of the winter bed-sites in daytime and nighttime. Compared with nighttime, the winter bed-site in daytime preferred by C. capreolus had the characteristics of larger arbor crown breadth, lower shrub height, denser ground cover, more concealment, and less length and width.

Influence of male hierarchy on female choice of Lasiopodomys brandtii

ZHANG Jian-jun^1,2;SHI Da-zhao²

2007, 26(02):  219-222 . 

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By using monitor and special behaviors recording method, a laboratory study was made on the influence of male hierarchy on female choice of L. brandtii. The results showed that there was no significant difference in odor preference and individual preference, no matter the female vole was on estrous or not. The estrous female took on more self-grooming behavior than the non-estrous female in both the odor preference and the individual preference experiments. On the selection priority, estrous female would first select the odor or individual of dominant male and mate with it, while non-estrous female would first select the odor or individual of subordinate male. The female choice of L. bramdtii was not only influenced by male hierarchy, but also influenced by the physiological status of female vole.

Food consumption and feeding characters of Phodopus roborovskii on Hunshandake sandy land of Inner Mongolia

WAN Xin-rong; LIU Wei; WANG Guang-he; ZHONG Wen-qin

2007, 26(02):  223-227 . 

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The Phodopus roborovskii individuals on Hunshandake sandy land of Inner Mongolia were trapped monthly, and the contents in their cheek pouch and stomach were analyzed to study the food consumption and feeding characters of P. roborovskii on the sandy land. The results showed that plant seeds were the main food of P. roborovskii, contributing more than 85% of the food consumption. P. roborovskii also took insects, plant leaves and stems as its food. The daily food consumption of P. roborovskii was highly correlated with its body weight, and the per unit body weight of juvenile P. roborovskii consumed more food than that of the adult. The functional relationship of daily food consumption (D) and body mass (M) could be expressed by D=1.422×lnM-1.780. Based on the population structure of P. roborovskii, its daily food consumption was calculated as about 2 g of plant seeds.

Morphological biology and fecundity of Odontobutis obscura in Huaihe River water system

QIAO De-liang;HONG Lei

2007, 26(02):  228-232 . 

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This paper investigated the morphological character, framework, and fecundity of Odontobutis obscura in Huaihe River water system, aimed to provide references for the morpholog-ical germplasm criteria and phylogenesis study of the fish. The results showed that in countable characters, the O. obscura in the water system had dorsal fin (D) Ⅶ, Ⅰ-9-10, caudal fin (C) 14-15, anal fin (A)Ⅰ-7-8, ventral fin (V) Ⅰ-5, pectoral fin (P) 14-15 rays, longitudinal scales 36-41, transversal scales 14-18, scales on lateral sensory papillae line 28-30, gill rakes on first gill arch 9-11, and vertebras 2829. In measurable characters, the total length was 1,23 times of body width, and body length was 3.82 times of body width, 3.08 times of head length, 5.19 times of caudal peduncle length, 1.86 times of alimentary canal length, and 6.99 times of intestine length. The head length was 2.94 times of snout length, 6.09 times of eye diameter,3.86 times of interorbital distance, and 1.94 times of mouth breadth. Body length was 0.96 times of body breadth, and caudal peduncle length was 1.66 times of caudle peduncle width. The fatness index was 2.90. On average, the absolute fecundity, relative fecundity to body length, and relative fecundity to body mass were 3 288 eggs, 308.7 eggs·cm^-1, and 102.3 eggs·g^-1, and the maturity indices for female and male were 12.87% and 1.13%, respectively.

Arthropod community diversity in jujube orchards with integrated and conventional pest management

SHI Guang-lu^1,2; WANG You-nian¹; ZHANG Tie-qiang¹; DU Yan-li¹; LIU Su-qi¹; MIAO Zhen-wang³; LI Deng-ke⁴; YU Tong-quan¹

2007, 26(02):  233-238 . 

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An investigation was made on the diversities of arthropod community, pest sub-community, and natural enemy sub-community in the mono-cultured and wheat-intercropped jujube orchards with integrated pest management (IPM) and conventional management (CM) in Taigu area of Shanxi Province. The results indicated that there were significant differences (P<0.05) in the diversity indices of the community and sub-communities among these four treatments at different stages of jujube tree growth. The F-test indicated that wheat-jujube intercropping combined with IPM was the main factor affecting the diversity indices of arthropod community, pest sub-community and natural enemy sub-community in jujube orchard ecosystem.

Comprehensive evaluation of ecological economic system in Funing County of Jiangsu Province

WANG Shu-yu^1,2;BIAN Xin-min¹

2007, 26(02):  239-244 . 

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Based on the theory of ecological footprint, the ecological economic system in Funing County of Jiangsu Province was analyzed in view of the demand and supply of natural resources by economic system. The concept of ecological deficit (ecological remainder) per ten thousand yuan GDP was proposed to evaluate the development of ecological economic system, and the society, economy, and ecological environment were considered as a whole. By using entire-array-polygon method and combining with calculated ecological deficit (ecological remainder) per ten thousand yuan GDP and Ulanowicz development capacity, the ecological economic system in Funing Coun-ty was evaluated. The results showed that in 1995—2003, the ecological deficit per ten thousandyuan GDP of Funing County decreased from 4.2278 hm² to 3.4704 hm², development capacity increased from 1.5751 to 3.5431, and comprehensive development index increased from 0 to 0.5051, illustrating that the ecological economic system in Funing County had a sustainable de-velopment, and the comprehensive index could properly reflect the development capacity of the region.

Inbreeding depression: Have we observed them?

WANG Zheng-feng¹; FU Sheng-lei¹; REN Hai¹; PENG Shao-lin²

2007, 26(02):  245-252 . 

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Inbreeding may reduce population fitness through the expression of recessive and dele-terious alleles in homozygous form. Small populations are more vulnerable for inbreeding depre-ssion, but their responses to the depression may not be observed due to the genetic load purged in studied species, benign environment investigated, differences in studied traits, different deve-lopment stages of studied species, and different family lines, populations, and individuals used. All of these imply that the levels of inbreeding depression are affected ecologically and genetically. The genetic bases of different traits are associated with different ecological factors, causing the expression of inbreeding depression differed in phenotypic traits.

Minirhizotron, a new technique for plant root system research: its invention, development and application

ZHOU Ben-zhi¹;ZHANG Shou-gong²;FU Mao-yi¹

2007, 26(02):  253-260 . 

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Root system is the dynamic interface of plant and soil, and of great significance to both of them. However, owing to the fact that it hides deep in the soil, the research on the root system is quite inconvenient, and lags behind that on plant aboveground part extensively and intensively. With the recognition of the significance of root in ecosystem and globe carbon bal-ance, root research has become one of the hotspots internationally. With the invention and development of minirhizotron technique, root research technique has made a great progress. Minirhizotron has been a milestone in the development of root research techniques. Minirhizotron system is composed of transparent observation tube, viewing equipment and recording equipment. Mirror, scope and camera have been used as the viewing equipment successively, while recording equipment experiences the history of hand-drawing, traditional photo or tape and digital camera picture. With the development of the root image analysis systems, this technique has been greatly improved. It allows us to observe nondestructively the initiation, elongation and death of the root at an interval, obtain the information on root length, rooting density and depth, lateral root spread, branching characteristic, mycorhiza characteristic, fine root dynamics, root system lifecycle and root catabolism, etc., and understand the responses of root system to various stress. This technique would certainly find a wider use in agricultural, forestry and environmental sciences.

Material flow analysis for economic-environmental system

XING Fang-fang; OUYANG Zhi-yun; YANG Jian-xin; ZHENG Hua; LUO Ting-wen

2007, 26(02):  261-268 . 

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Economy and environment are linked by material and energy flow, while the imbal-ance of the flow is the key cause inducing environmental problems. Through tracing and est-imating the material input, output and stock within economicenvironmental system, material flow analysis can provide a scientific guide to dematerialization and sustainable development. Substance flow analysis (SFA), and material flow accounting and analysis (MFA) are the main types of material flow analysis. SFA tracks the flows of specific substances (e . g ., elements or compounds), often with the intent of identifying environmental problems and seeking for pot-ential solutions, while MFA usually regards economic system as a “black box” and analyzes its material throughput. In this review, a detailed description was made on SFA and MFA, and their similarities and differences in methodology and application were analyzed, with the future res-earch directions of material flow analysis discussed.

Flood pulse concept and its application in river-floodplain system

LU Xiao-ning^1,3;DENG Wei^1,2; ZHANG Shu-qing^1,3

2007, 26(02):  269-277 . 

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As the fourth river-ecological theory after river continuum concept, flood pulse concept mainly states the ecological significance of lateral hydrological connectivity between river and its floodplains in the processes of river-floodplain system, with emphasis on the importance of flood pulse and the integrity of river-floodplain system. This paper mainly introduced the conceptual model of flood pulse, its main viewpoints, and application advances in river-floodplain system. Three aspects of flood pulse concept were applied. On the aspect of physiognomic processes, the‘dominant’ discharge of channel form was particularly emphasized. On the biogeochemical cycle, nitrogen study took the first place,and flood pulse was considered as the principal driving force for the metabolism and biogeochemical cycle of river-floodplain system. As for the biological processes in river-floodplain system, most studies were focused on macrophytes and the animals represented by water birds and fish. It was indicated that intentional flood pulse should be advo-cated as a restorative management strategy for the improvement of plant productivity, management of exotic species, and restoration of overall biodiversity. In arid regions, the main issues for water birds conservation were the frequency and extent of flooding effects on the distribution of breeding habitat and/or refuge, and the water use across the landscape, which were of vital significance to the wetland water birds conservation in arid/semiarid areas of west Songhuajiang-Nenjiang Plain. The flood pulse concept was developed on the basis of the observations on neotropical Amazon river. With its application in other types of areas, the functions of other environmental factors excluding flood pulse sticked out, and the ecological effects of human disturbanceson flood pulse were more and more visualized. Therefore, the study on the variations of floodplain processes under the coupling effects of flood pulse and other environmental factors with the disturbance of human activities should be strengthened, and accordingly, a universal model of relatively stronger appli-cability could be brought forward.

Soil organic carbon pool and its affecting factors in farmland ecosystem

JIANG Yong¹;ZHUANG Qiu-li^1,2;LIANG Wen-ju¹

2007, 26(02):  278-285 . 

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The maintenance and improvement of soil fertility greatly rest with the quantity and quality of soil organic carbon (SOC), while the study of SOC pool in farmland ecosystem is a main research direction of agricultural, ecological,and environmental sciences. Land use, cul-tivation, crop selection, planting density, irrigation, fertilization, and other anthropogenic act-ivities all affect the dynamics of SOC pool. This paper summarized the research advances on the SOC pool and its affecting factors in farmland ecosystem, soil C sequestration potential, measures for maintaining and improving SOC pool, and potential roles of farmland soil C sequestration in mitigating greenhouse gases emission and climate change. The future research directions of SOC pool in farmland ecosystem were also put forward.

Dynamics of soil animals during decomposition of Korean pine stump

TIAN Zi-hang;ZHANG Chun-yu;ZHAO Xiu-hai

2007, 26(02):  286-290 . 

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To study the dynamics of soil animals during the decomposition of Korea pine stump, a broadleavedKorean pine mixed forest after selective cutting was selected , and soil samples were collected in a 14-year span, with different size soil animals identified and counted. The results showed that the groups and numbers of soil animals increased with increasing decomp-osition duration, being the maximum in the 10th year, but decreased with increasing depth of the stump in soil, few of them being found at the bottom of the stump.

Evaluation of eco-environmental frangibility in West Jilin Province based on matter-element model

WANG Ming-quan^1,2; WANG Jin-da¹; LIU Jing-shuang¹; DOU Jing-xin¹

2007, 26(02):  291-295 . 

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West Jilin Province is a typical area of the ecotone between agriculture and animal husbandry with frangible eco-environment. From the aspects of water resources, natural disasters and land degradation, 10 indices were selected to establish matter-element model for the assess-ment of eco-environmental frangibility in West Jilin Province. The results indicated that in 1985—2000, Qianan, Fuyu and Changling Counties had the least frangibility (level Ⅰ), Daan and Qianguo were in the second place (level Ⅱ), and Taobei, Zhenlai, Taonan, and Tongyu had the highest frangibility (level Ⅲ). As a whole, the counties in Songyuan City were less frangible than those in Baicheng City. Different counties had different sensibility to the environmental factors, e . g ., Daan and Tongyu were most frangible in water resources condition, and Taobei, Zhenlai, Taonan, Tongyu and Qianan suffered most from natural disasters, while Taobei, Taonan, Qianguo were threatened by severe land degradation.

Health assessment of Shahu Lake aquatic ecosystem in Ningxia

MI Wen-bao^1,2; FAN Xin-gang³; LIU Ming-li⁴

2007, 26(02):  296-300 . 

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In this paper, seven indices including pH, SS, DO, COD, BOD, TP and NH₄⁺-N were measured to calculate the integrative pollution index of Shahu Lake in Ninxia and to evaluate the exterior stress on the aquatic ecosystem of the Lake. The exergy, structural exergy, and plankton’s biomass and productivity of the aquatic ecosystem were also investigated in macro-scale. The results showed that the Shahu Lake aquatic ecosystem had a decreased vigor. Its bio-logical turnover slowed down, utilization of environmental resources weakened, population in-crease was interfered by human activities, biodiversity decreased, and eutrophication tended to be severe and further deteriorated. The aquatic ecosystem of Shahu Lake was in non- or sub-healthy state.