Table of Content

10 November 2008, Volume 27 Issue 11

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Articles

Gap characteristics and its effects on community regeneration of Quercus liaotungensis forest on Loess Plateau.

ZHANG Lü-zui; WANG Xiao-an; GUO Hua; LI Feng

2008, 27(11):  1835-1840 . 

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A quantitative study was made on the Quercus liaotungensis forest gaps in Malan area of Loess Plateau. The results showed that small gaps (20-40 m²) and middle gaps (40-60 m²) were the dominant, and the age structure of the gaps was mostly at metaphase and anaphase. The main manners of gap formation were standing death and stem breakage, which accounted for 70.31% of the total gaps, and the numbers of forest gap-makers were mostly 1-3, suggesting that the forest gaps were mainly formed by natural disturbance. Among the gap border trees, Q. liaotungensis was the dominant. In the gaps, the abundance of Q. liaotungensis with different life history stages had different responses to the environmental factors. The abundance of seedlings was highly correlated with gap size and the height of gap border trees (R²=0.429,P<0.01), that of saplings was highly correlated with the intensity of scattered light (R²=0.286,P<0.01), and that of adult trees was not significantly correlated with environmental factors but significantly correlated with sapling abundance (R²=0.175,P<0.05).

Ecological gradients of plant communities in South Lüliang Mountains of Shanxi.

LI Jin-peng^1,2; GUO Dong-gang²; ZHANG Qiu-hua²; SHANGGUAN Tie-liang^1,2

2008, 27(11):  1841-1846 . 

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South Lüliang Mountains of Shanxi is located in the ecotone between south and north warm temperate deciduous broad-leaved forest subzones, according to the China’s vegetation regionalization. By the methods of TWINSPAN and DCCA, this paper studied the ecological gradients of the plant communities in South Lüliang Mountains, in terms of the interactions between plant species and communities and environmental factors. Based on TWINSPAN, 74 quadrats were classified into 18 associations, in which, 4 associations were forest communities, and 14 associations were shrubs. These 18 associations, all in the criteria of secondary vegetation types in south warm temperate zone, represented the major plant communities in South Lüliang Mountains. Field survey also showed that the 18 associations had been subject to anthropogenic disturbances. DCCA ordination of the plots satisfactorily revealed the relationships between the distribution patterns of the plant communities and the environmental components (altitude, slop degree, soil layer depth, litter layer thickness, slope aspect, and human disturbance). The dominant factors controlling the distribution patterns of the plant communities were altitude and human activities, while slope aspect and soil layer depth also had effects on the community characteristics. There existed significant correlations among altitude, human disturbance, and litter layer thickness, which were identified as the dominant factors affecting the community distribution. The integration of the results from TWINSPAN and DCCA analyses clearly showed the vertical distribution of the plant communities in the study area. At the low hills and valleys with an elevation of 690-1 100 m, the dominant plants were Vitex negundo var. heterophylla and Zizinhus jujuba var. spinosa; at the southern and semi-southern slopes with an elevation of 1100-1300 m, mainly distributed Quercus baronii and less distributed Platycladus orientalis and Carpinus turczaniowii; and at the elevation of 1 300-1 570 m, the major communities were the forests dominated by Quercus wutaishanica. The distribution of Q. baronii was the main sign of the ecotone between south and north warm temperate deciduous broad-leaved forest subzones in this area.

Morphological differentiation of fruits and seeds of endangered plant Camellia nitidissima.

CHAI Sheng-feng; WEI Xiao; JIANG Yun-sheng; CHEN Zong-you; QI Xiao-xue; WANG Man-lian

2008, 27(11):  1847-1852 . 

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The fruits and seeds of endangered plant Camellia nitidissima were collected from five natural populations in Nazishan (NZSH1, NZSH2, and NZSH3), Dawangjiang (DWJ) and Gengmaoshan (GMSH), and one artificial population in Guangxi Institute of Botany (GIXB). Based on the 15 characters of fruits and seeds, the morphological differentiation of the six populations was studied. According to the size of fruits and seeds, the six populations were in the order of GIXB > NZSH2 > DWJ > GMSH > NZSH3 > NZHS1, and there existed differences among and within the populations of C. nitidissima. The average variation coefficient of different characters among populations ranged from 0.429 (seed mass per fruit, SMPF) to 0.069 (shape of fruit, FT/FD), and the FT/FD was a relatively stable character; while the average variation coefficient of different populations ranged from 0.287 (NZSH3) to 0.155 (GXIB). In the 15 characters, the variations of 3 characters (such as fruit diameter and mass) were significant (P<0.05), and those of 7 characters (such as seed length and width) were very significant (P<0.01). There was an evident morphological differentiation among most populations. Cluster analysis showed that the morphological differentiation was not correlated with the geographic distance among populations. The major factors affecting the morphological differentiation of fruits and feeds were altitude, soil organic matter, soil water, and light transmittance of canopy.

Ecological division of vegetations in Northeast China.

XUE Wen-duo¹; HE Xing-yuan¹; CHEN Wei¹; LIU Chang-fu²; ZHAO Gui-ling²; ZHOU Yuan²

2008, 27(11):  1853-1860 . 

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Ecological vegetation division is the basis of rational exploitation and ecological management of vegetation resources. Based on the analysis of the characteristics and distribution patterns of vegetations in Northeast China, the principles and index system of ecological vegetation division were discussed, and the division system was established. Four ecological vegetation regions, eleven ecological vegetation sub-regions, and thirty-four ecological vegetation districts were divided. The first division borderline of China vegetation division in the Northeast China ecological vegetation division was discussed.

Alien plants in limestone regions of Hainan Island, China.

QIN Xin-sheng^1,2; ZHANG Rong-jing^2,3; CHEN Hong-feng²; YAN Yue-hong⁴; ZHENG Xi-long²; XING Fu-wu²

2008, 27(11):  1861-1868 . 

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Based on the field survey and literature review, the species composition, distribution, origin, life form, invasion habitat, damage degree, and invasion track of alien plants in limestone regions of Hainan Island were studied, and compared with those in neighboring regions. The results showed that in the limestone regions of Hainan Island, there were 53 species of alien plants, belonging to 45 genera and 22 families. Most of the alien species (77.4%) were originated from tropical America, and many of them (77.4%) were herbs. These alien plants were introduced by intentional (47.2%) or unconscious (35.8%) human activities. They were mainly distributed in the hillsides, margins or gaps of forests, and croplands at low altitude, and a few of them were found in the forests at high altitude. Through the comparison with those in neighboring regions, it was found that the alien plants in the limestone regions in Hainan Island could more easily invade islands and littorals than invade inlands, and the total number of the alien plants and its proportion to the native plants were closely related to human activities such as frequent foreign trade.

Effects of enhanced UV-B radiation on the morphology, physiology, and chemical composition of Amaranthus retroflexus.

ZHANG Rui-huan; LIU Xiao; TIAN Xiang-jun; YUE Ming

2008, 27(11):  1869-1875 . 

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With field pot experiment, the effects of two dosages of enhanced UV-B radiation on the morphology, physiology, biomass allocation, and chemical composition of C₄ plant Amaranthus retroflexus were studied. The results indicated that under the effects of enhanced UV-B radiation, the branch number, leaf number, plant height, and stem diameter had less change, the plant CAT activity was significantly higher than that of the control (P<0.05), but the SOD activity was less affected. The POD activity was significantly higher than the control under low dosage UV-B radiation, but had less change under high dosage UV-B radiation. The MDA content increased with increasing UV-B radiation (P<0.05). Under low dosage UV-B radiation and at harvest, the biomass allocation in leaf increased significantly but that in root was in adverse; while under high dosage UV-B radiation, less change was observed in the allocation. UV-B radiation induced significant changes in the chemical composition of root, stem, and leaf. Under UV-B radiation, the soluble protein, lignin, and fat contents in leaf, lignin content in root, and cellulose and lignin contents in stem were increased, while the starch content in leaf and the soluble sugar, starch, and fat contents in stem were decreased significantly (P<0.05), compared with the control.

Distribution characteristics and seasonal dynamics of N, P and K in wetland plants in upper shoal of Jiuduansha, Shanghai.

LIU Chang-e¹; YANG Yong-xing¹; YANG Yang²

2008, 27(11):  1876-1882 . 

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From April to December 2005, the main wetland plant species Scirpus mariqueter, Spartina alterniflora, and Phragmites australis in the upper shoal of Jiuduansha at the estuary of Yangzi River were sampled monthly, and their N, P, and K contents were determined. The results showed that the test plant species had different distribution characteristics of N, P, and K. The nutrients contents in different species and in different organs of the same species differed with the rhythm of plant growth. Biomass was the main factor limiting the stocks of the nutrients in different plant species and organs. The N, P, and K stocks decreased in the order of Phragmites australis>Spartina alterniflora>Scirpus mariqueter, and their contents in different plant organs varied with time. In stalk, the K content decreased while the N content increased from April to May; in all kinds of organs, the P content decreased from May to June; and in leaf, the N content was higher than that in other organs from June to October.

Effects of water-saving agents on drought resistance of Davidia involucrate seedlings: Model construction, principal and mutual effect analysis, and optimization choice.

XUE Bo¹; LI Xian-wei¹; ZHANG Jian¹; FAN Chuan¹; LIU Shuo²

2008, 27(11):  1883-1894 . 

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Davidia involucrate, a relic species of paleotropical kingdom in Tertiary period and belonging to Davidiaceae with a single genus, is one of the first-class protective plants in China. In this paper, a pot culture experiment with quadratic general rotation design was conducted to study the effects of CaCl₂,salicylic acid (SA), and a water-retention agent on the drought resistance of D. involucrate seedlings. The results showed that all test reagents had positive effects, and synergistic effect existed among them. CaCl₂ and SA improved the water utilization efficiency of D. involucrate at the initial stage of water stress, while water-retention agent maintained higher soil moisture content when the drought stress developed so as to improve the drought resistance of D. involucrate and alleviate the effects of water stress. The optimum combination of management practice in improving drought resistance of D. involucrate seedlings was 839.400-1256.520 mg·L^-1 CaCl₂, 44.015-69.306 mg·L^-1SA, and 618-700 ml·pot^-1 water-retention agent.

Effects of two bacillus strains on microbial community structure in rhizosphere soils of cucumber and tomato.

CHEN Xue-li^1,2;WANG Guang-hua¹;JIN Jian¹;WANG Yu-feng²

2008, 27(11):  1895-1900 . 

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In a pot experiment, the effects of bio-control bacterial strains Paenibacillus polymyxa and Bacillus subtilis on the microbial community structure in the rhizosphere soils of cucumber and tomato were examined by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Principal component analysis (PCA) of DGGE banding patterns indicated that the effects of the two bacillus strains varied with cropped plants. In the rhizosphere soil of cucumber, no significant effects were observed on the structures of bacterial and fungal communities, but that of fungal community changed obviously with sampling time; while in the rhizosphere soil of tomato, the structure of bacterial community was less affected but changed obviously with sampling time, and the structure of fungal community was significantly affected. It was suggested that vegetable species was the major factor determining the microbial community structure in rhizosphere soil. Inoculation with test two bio-control bacterial strains had little effects on the structure of bacterial community, but its effects on fungal community structure differed with vegetable species.

Mineralization rates of soil organic carbon along an elevation gradient in Wuyi Mountain of Southeast China.

ZHOU Yan¹; XU Xian-gen¹; RUAN Hong-hua¹; WANG Jia-she²; FANG Yan-hong²; WU Yan-yu²; XU Zi-kun²

2008, 27(11):  1901-1907 . 

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With incubation test, this paper studied the mineralization rate and mineralization ratio of soil organic carbon (SOC) along an elevation gradient in the Wuyishan National Nature Reserve of Fujian Province, Southeast China. Soil samples with a field water capacity of 60% were incubated at 25 ℃ over 110 days. The mineralization rate of SOC increased with increasing elevation, and that in 0-40 cm layer under alpine meadow (0.08 g CO₂-C·kg^-1·d^-1) was 14.3%, 60.0%, and 166.7% greater than that under dwarf forest, coniferous forest, and evergreen broadleaf forest, respectively, with the difference mainly existed in 0-10 cm layer. The mineralization ratio of SOC in 0-40 cm layer under coniferous forest (16.6%) was 37.0%, 67.6%, and 79.1% higher than that under dwarf forest, evergreen broadleaf forest, and alpine meadow, respectively. The mineralization rate and mineralization ratio of SOC decreased with soil depth, and the decrement differed significantly (P＜0.05) with the soils at different elevations. It was suggested that elevation gradient had significant effects on the mineralization rate and mineralization ratio of SOC.

Soil seed bank and its relations with vegetations on a grassland in Jinsha River dry-hot valley.

ZHANG Jian-li;ZHANG Wen;BI Yu-fen

2008, 27(11):  1908-1912 . 

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In 2005 and 2006, investigations were made on the soil seed bank, plant community composition, and vegetation density on a typical degraded grassland in Jinsha River dry-hot valley, which was enclosed in 2004, with the relations of soil seed bank with vegetations analyzed. The results showed that the density of soil seed bank was significantly positively correlated with the density of vegetations in the year of enclosure (P<0.01), and the regression equation could be well expressed by quadratic curve. The soil seed bank under Heteropogon contortus, Digitaria ciliaris, Bulbostylis densa, and Fimbristylis dichotoma populations had significant positive correlations with the vegetation density of the populations (P<0.01), while that under Pasdpalum paspalodes, Poa acroleuca, Arthraxon breviaristatus, Oxalis corniculata, Bidens pilosa, and Phyllanthus urinaria populations were not.

Secondary seed dispersal of Ficus benjamina: New evidence for ant-nonmyrmecochorous mutualism.

ZHANG Shuang^1,2; CHEN Jin¹

2008, 27(11):  1913-1919 . 

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The secondary dispersal of small seeds in tropical forest mediated by ants often determines the final arrival site of the seeds and their fate. With Ficus benjamina, a bird-dispersed nonmyrmecochorous fig species, as test object, this paper investigated how ants respond to its seeds with different treatments (seeds from fruit with pericarp, seeds from fruit with pericarp removed, seeds from bird’s feces with pericarp, and seeds from bird’s feces with pericarp removed). Four ant species, i.e., Pheidole rhombinoda, Monomorium pharaonis, Odontoponera transversa and Paratrechina bourbonica, were recorded in the seed dispersal. The visiting frequency of the four ants was 71.7%, 23.3%, 2.5% and 2.5%, respectively, and the mean dispersal distance was 179 cm±13 cm (n=159). The major dispersal ant Ph. rhombinoda discarded 58.6% of the carried seeds in the refuse piles after consuming the pericarp. The seeds collected from ant’s refuse piles had a significantly enhanced seed germination rate (from 49.3% to 93.3%). Seed removal rate decreased significantly after the pericarp was removed (from 75.0% to 29.5%). Seed pericarp enhanced the attraction to ants, and the seeds treated by ants gained significant higher germination rate. Therefore, a significant mutualism relationship existed between F. benjamina and its dispersal ants.

Stability in protein and amylose contents of rice cultivars and relationships between genotype-environment interaction and climate factors.

HUANG Yuan-cai¹; JIA Yan²; LIU Jiang¹; JIANG Xiu-ying³; SHEN Feng³; LI Xiu-fen¹

2008, 27(11):  1920-1925 . 

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Based on AMMI model, the stability in protein and amylose contents of 25 rice cultivars in Liaoning Province was analyzed, with the relationships between genotype-environment (G×E) interaction and climate factors as well as the eco-climatic adaptability of the rice cultivars discussed. The results showed that the cultivars V3 (Liaojing 294), V15 (Shennong 9810) and V11 (0157) had higher stability in protein content, while V2 (Liaonong 49), V13 (Shennong 693) and V1 (Xian S38) had higher stability in amylose content. Temperature and sunlight were the main climatic factors affecting G×E interaction. For protein content, V12 (Huajing 49) and V9 (Shennong 9819) performed significant adaptability to relatively low temperature and scant sunlight; while for amylose content, V20 (Xing 3), V21 (Dongya 03-51) and V6 (Maoyang 1) had specific adaptability to low temperature and scant sunlight, low temperature and more sunlight, and high temperature and more sunlight, respectively.

Influence of different preceding crops on nitrogen fertilizer effect of flue-cured tobacco.

XU Zhao-li; YANG Yu-hong

2008, 27(11):  1926-1931 . 

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In order to rationally choose the preceding crops of rotated flue-cured tobacco, the influence of different preceding crops on the availability of nitrogen fertilizer to flue-cured tobacco was studied by isotope ¹⁵N trace technique in a field plot and micro-plot experiment. The results showed that applying nitrogen fertilizer decreased the total sugar content but increased the nicotine content in the leaves at the middle and lower parts of tobacco plant, showing a harmonizing role on the sugar/nicotine ratio. The residual fertilizer nitrogen in soil varied with preceding crops, resulting in different biomass of flue-cured tobacco. Under the conditions of no nitrogen fertilizer application, the effects of preceding crops on the biomass of flue-cured tobacco were in the order of Hordeum vulgare<Allium cepa<Pisum sativum<Brassica napus. Preceding crop, nitrogen application rate, and their interaction significantly affected nitrogen fertilizer utilization efficiency (P<0.01), and affected the economic traits of tobacco, such as the proportion of upper grade leaves, yield, and production value. It was indicated that Hordeum vulgare and Pisum sativum were the better preceding crops of rotated flue-cured tobacco.

Seasonal variation of microclimate’s edge influence depth at the interface of farmland and forest ecotone.

LIN Chang-cun; WANG De-li; CAO Yong-hong; YANG Yun-fei; ZHU Ting-cheng

2008, 27(11):  1932-1936 . 

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By using moving split-window techniques (MSWT) and based on the estimation of microclimate in dry and rainy seasons, this paper analyzed the seasonal variation of microclimate’s edge influence depth at the interface of farmland and forest ecotone in west Jilin Province, aimed to provide information for improving current management practice and production in the study area. The results showed that in forestland, the squared Euclidean distance (SED) curve on the moving split-window graph had a stable variation, with a peak at 40 m in dry season and at 20 m in rainy season; while in farmland, the microclimate’s edge influence depth had no obvious spatiotemporal change, with the peak of SED curve at 60 m in both dry and rainy seasons. The edge influence depth was more far in farmland than in forestland, and there was a seasonal variation in forestland. It was suggested that the microclimate’s edge influence depth at the interface of farmland and forest ecotone in west Jilin varied with time and space, and depended on the vegetation’s aspection at the two sides of the interface and the intensity of human disturbance.

Community structure and diversity of spider in Zhangshiyan scenic area of Hebei Province, China.

ZHANG Feng; ZHU Li-min

2008, 27(11):  1937-1940 . 

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The community structure of spider in Zhangshiyan scenic area of Zanhuang County, Hebei Province, China was studied in July 2007. With sampling and sweep-netting together, 1 226 spider individuals were collected, which belonged to 24 families, 61 genera and 81 species. The species richness of the spider was abundant, and Agelenidae, Thomisidae, Linyphiidae, and Lycosidae were the dominant groups. Both the species number and the individual density in different habitats were different. Shrubs had the most species (54), highest density (20.9 ind·m^-2) and Shannon diversity index (3.264), forest floors had the highest concentration index (0.116) but the lowest evenness index (0.749), while bottomlands had the highest evenness index (0.853), which was related to the fact that most of the species were wandering spiders. The community structure of the spider was coincident with Fisher’s logarithm series distribution.

Quantitative distribution of earthworms and its relationships with environmental factors in tropical secondary forest and rubber plantation in Xishuangbanna.

DU Jie^1,2; YANG Xiao-dong¹; ZHANG Hua^1,2; YU Guang-bin^1,2

2008, 27(11):  1941-1947 . 

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To understand the influence of land use change on earthworm communities, the quantitative distribution of earthworms and its relationships with environmental factors in the tropical secondary forest and rubber plantation in Xishuangbanna, Southwest China were studied in January 2006. The results showed that after the secondary forest converted into rubber plantation, soil nutrients and organic C input from plants reduced significantly, and earthworm communities altered. In rubber plantation, the density of tropical exotic earthworm (Pontoscolex corethrurus) (52.27 ind·m^-2) was significantly higher than that of native earthworm (Amynthas sp.) (0.53 ind·m^-2); while in secondary forest, no significant differences were observed in the density and biomass of the two earthworm species. The density (0.53 ind·m^-2) and biomass (0.32 g·m^-2) of Amynthas sp. in rubber plantation showed a decrease trend compared with those in secondary forest (6.93 ind·m^-2, 7.76 g·m^-2). An increasing population of P. corethrurus was accounted by the larger proportion of its juvenile’s density and biomass, while Amynthas sp. was mainly composed of adults. The fine-root biomass of rubber plantation was positively correlated with the density of P. corethrurus. It was suggested that the vegetation change and soil nutrient decrease due to the conversion of secondary forest into rubber plantation had promoted the reproduction of exotic earthworm, and the adaptive strategies of exotic and native earthworms could not be ignored.

Comparison of planktonic crustaceans in north and south branches at Yangtze River estuary and impact prediction of South-to-North Water Transfer Project.

PENG Jian-hua¹; ZHENG Jin-xiu¹; MA Pei-ming¹; WU Sheng-gui¹; PENG Qi²; WAN Cheng-yan¹

2008, 27(11):  1948-1954 . 

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The implementation of South-to-North Water Transfer Project will bring about some impacts on the ecological environment of aquatic organisms at Yangtze River estuary. Planktonic crustaceans are the one of important components of aquatic organisms. In this study, the planktonic crustaceans in the north and south branches at Yangtze River Estuary were surveyed in autumn 2005 and spring 2006, with the region from Xuliujing to lighthouse 50 on the estuary, a total length of 181.8 km, and a broad expansion from west to east about 5.7 km to about 90 km with a fan-shape. Three cross-sections and 14 survey points were established. A total of 54 planktonic crustacean species, which belonged to 37 genera under 23 families, were recorded. There were 15 species of cladocerans belonging to 8 genera under 6 families, and 39 species of copepods belonging to 29 genera under 17 families. More planktonic crustacean species were observed in autumn than in spring, and more copepod species were found in north branch than in south branch. Planktonic crustaceans had an average density of 9.10 ind·L^-1, and their total biomass, mainly composed of copepods, was 0.1179 mg·L^-1. The standing crop at cross-section III in the north branch was far higher than that at other sections. Bosmina longirostris and Bosmina coregoni were the dominant species of cladocerans, and Sinocalanus sinensis, S. dorrii, Schmackeria forbesi and Mesocyclops pehpeiensis were the dominant species of copepods. The overall level and spatiotemporal distribution of planktonic crustaceans in the north and south branches of Yangtze River estuary and the impacts of the Water Transfer Project on the planktonic crustaceans were also analyzed.

Analysis of haplotypes of mtDNA 16S rRNA genes of wild tiger prawn (Penaeus monodon) in coastal waters of South China.

ZHOU Fa-lin^1,2; JIANG Shi-gui¹; JIANG Yong-jie¹; HUANG Jian-hua¹

2008, 27(11):  1955-1959 . 

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A total of 100 Penaeus monodon samples were collected from five locations (Sanya, Shenzhen, Yangjiang, Zhanjiang, and Beihai) in the coastal waters of South China, and PCR technique was used to amplify the mtDNA 16S rRNA of the 100 individuals. The PCR products were purified and sequenced. 440 bp nucleotide sequences of partial 16S rRNA were obtained (some of the marginal sequences were excluded), and 19 haplotypes and 28 variable sites were detected. A high percentage (69.0%) of A+T base composition in the 19 haplotypes was observed. The pairwise distances among the 19 haplotypes ranged 0.002-0.033. The median-joining network of the 19 haplotypes did not distinguish distinctly into five-location groupings of haplotypes. All the haplotypes were scattered throughout the network. Among the 19 haplotypes, the haplotype 7 was ancestral haplotype, and the other 18 haplotypes were originated from haplotype 7, according to the distribution of haplotypes in five locations and median-joining network of 19 haplotypes.

Eutrophication characteristics of pumped- and non-pumped type reservoirs in South China.

LIU Lei; HU Ren; GU Ji-guang; HAN Bo-ping

2008, 27(11):  1960-1965 . 

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In coastal areas short of fresh water resources, pumped- and non-pumped type reservoirs play an important role in both urban and rural drinking water supply. In order to understand the eutrophication characteristics of these reservoirs, three pumped type reservoirs and three non-pumped type reservoirs were investigated in April, August, and December 2006. In pumped type reservoirs, the mean concentrations of total nitrogen, total phosphorus, and chlorophyll a were higher than those in non-pumped type reservoirs, but the mean Secchi disk depth was lower than that in non-pumped type reservoirs. In pumped type reservoirs, the concentrations of total nitrogen, total phosphorus, and chlorophyll a were higher in winter and spring than summer; while in non-pumped type reservoirs, they were in adverse. The phytoplankton biomass was slightly higher in pumped than in non-pumped type reservoirs. The seasonal dynamics of the dominant phytoplankton species were different in the two types of reservoirs. Pseudanabaene sp., Microcystis aeruginosa, and Aulacoseira granulate were dominant in pumped type reservoirs, while Peridinium sp. dominated in non-pumped type reservoirs. The eutrophication index of pumped type reservoirs was higher than that of non-pumped type reservoirs. PCA showed that nutrient was the dominating factor affecting the eutrophication in pumped type reservoirs, while temperature was the dominating factor in non-pumped type reservoirs. Pumping water into reservoirs modified the nutrients concentration and hydrologic process in pumped type reservoirs, leading to a significant difference in the eutrophication degree between pumped and non-pumped type reservoirs, and also, different seasonal patterns of eutrophication.

Chemical forms and pollution characteristics of heavy metals in Yellow River sediments.

YUAN Hao^1,2; WANG Yu-chun¹; GU Shang-yi²; LU Jin¹; ZHOU Huai-dong¹; WAN Xiao-hong¹

2008, 27(11):  1966-1971 . 

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The sediments from Yellow River were collected in 2004. Their heavy metals (Cu, Zn, Pb, Cd, Cr, As, and Hg) concentrations were determined, chemical forms were analyzed with BCR sequential extraction method, and pollution level and ecological risk were evaluated by the methods of geological index (I_geo) and ratio of secondary to protogenic (RSP). The results showed that the overall characteristics of the heavy metals concentrations in the sediments basically accorded with the abundance trend of the heavy metals in the shale at global scale. However, in parts of heavier polluted regions, there existed definite geographical diversity. From the viewpoint of concentration level, the contamination status of the heavy metals was not very serious. The Cu, Zn, Cr and As in the sediments were mainly in residual form, suggesting that they had better environmental stability; while Pb, Hg and Cd were more in highly active form, suggesting that they had greater environmental effects. Pb, Hg and Cd had high ecological risk index, and especially, the potential risk of Pb should be attached more importance to.

Temperature and humidity effect of urban green spaces in Beijing in summer.

LIU Jiao-mei¹; LI Shu-hua²; YANG Zhi-feng¹

2008, 27(11):  1972-1978 . 

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In order to testify the environmental effect of urban green spaces with different coverage and multiple layer structure, three typical urban green spaces, i.e., tree-shrub-herbage mixture, tree-herbage mixture, and lawn (treated as a control), in Yuan Da-Du Park in Beijing were selected to measure their microclimate in summer. The air temperature and relative humidity above the green spaces were measured continuously in horizontal and vertical directions. The results showed that during the high temperature period in summer, the air temperature above the green spaces decreased with increasing coverage, but the significant ecological effects of the lowering temperature and increasing relative humidity were not observed until the coverage of the spaces was higher than 60%. The tree-shrub-herbage mixture with higher coverage brought about a wider range of temperature and humidity effect, and had a greater effect on lowering temperature and increasing humidity, compared with the lawn. Reasonable structure and composition of plant community could make the urban green spaces better exert their effects in decreasing temperature and increasing humidity in summer, and thus, be beneficial to the improvement of urban environment and the mitigation of urban heat island effect.

Dynamic analysis on settlement percentage coverage in urbanization.

SHI Qin¹; LIU Mao-song¹; SONG Jin-qi²; XU Chi¹; CHEN Hong¹

2008, 27(11):  1979-1984 . 

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To reveal the relationships between the dynamics of settlement and its original status in urbanization, the changes of settlement percentage coverage (SPC) from 1988 to 2006 were studied with a method of neighborhood analysis based on the 1988, 1998 and 2006 Landsat TM images of Nanjing. The results showed that in 1988-2006, the total settlement area increased continuously and the landscape units with increased SPC dominated all the time, but lots of the landscape units with decreased SPC appeared from 1998 to 2006. With the rising original SPC value, the mean amplitude of the SPC of relevant landscape units mounted up and peaked at approximately 30%, and then descended gradually to negative value. In 1988, 1998 and 2006, the frequencies of the landscape units with lower SPC were higher than those with higher SPC, but the gap between the frequencies of the landscape units at lower SPC intervals (0 to 3%) and those at higher SPC intervals (>3%) narrowed in urbanization. In the time periods of 1988-1998 and 1998-2006, there were apparent differences between the curves of total settlement areas at relevant SPC intervals, but the curves of both increased and decreased areas were similar in shape.

Effects of land use change on the habitat of wild animals in Wenchuan County of Sichuan.

ZHANG Wen-guang^1,2,3; HU Yuan-man¹; HU Jin-chu²; LIU Miao^1,3; ZHU Jiao-jun¹; HU Zhi-bin¹

2008, 27(11):  1985-1989 . 

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Based on field investigation and geographic information system technology, the land use change in Wenchuan County of Sichuan Province from 1974 to 2000 was analyzed, and the habitat suitability for wild animals was evaluated by using habitat suitability model, with the change causes of suitable habitat analyzed. The results showed that from 1974 to 2000, the study area had an obvious land use change, with forest area decreased dramatically while the areas of grassland, shrub land, and farmland increased. The suitable habitat and its core area for wild animals decreased, and the distance between the core areas increased, which was not beneficial to the protection of wild animals. The increasing population and economy were the main causes for this change, and hence, the protection of wild animal habitat should be strengthened with the development of economy.

Ecological security assessment of heavy debris flow regions: A case study in Wenchuan County.

WANG Xi-lin; XIE Bao-yuan; GUAN Wen-bin

2008, 27(11):  1990-1996 . 

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In this paper, an index system based on topography, vegetation, climate, and social-economic data was built to assess the ecological security of Wenchuan County in Sichuan Province, and Geographical Information System technology and Principal Component Analysis method were used for the ecological security assessment of 119 catchments in the County. The results showed that (1) the ecological security in the heavy debris flow regions was closely related to topography, and unreasonable human disturbance greatly affected the ecological security and ecosystem stability, (2) the areas of insecurity, relative insecurity, and critical security made up about 41.17% of the total area, and most of them were along Minjiang River, (3) the grading of ecological security index was consistent with the actual status by validation.

Emergy analysis of eco-economic system in Wenchuan County of Sichuan Province.

LIU Miao; HU Yuan-man; CHANG Yu; BU Ren-cang

2008, 27(11):  1997-2001 . 

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Based on emergy theory and its analysis approach, and by using statistical and field survey data, the eco-economic system in Wenchuan County of Sichuan Province in 1982-2002 was analyzed. The results showed that this County had a poorer economic level and a smaller economic size. The input of emergy mainly came from renewable resources; while the output of emergy mainly came from un-renewable resources, and fossil and cement products took the main parts. Wenchuan exported huge amount of emergy, with the items including fossil and wood resources. The export of emergy, especially of wood emergy, had brought ecological problems due to vulnerable ecosystem. In the County, the emergy consumption per capita was small and the living standard was low, and thus, much attention should be paid to the harmonious development of economy and ecology.

Spatiotemporal pattern of ecological cropland conversion and vegetation succession: A review.

QIU Yang¹; ZHANG Ying¹; HAN Jing¹; WANG Jun²; MENG Qing-hua³

2008, 27(11):  2002-2009 . 

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This paper reviewed the studies about the spatiotemporal pattern of ecological cropland conversion and its effects on the spatiotemporal variation of vegetation succession, with the focus on the Loess Plateau of China. Recently, ecological cropland conversion is very popular all over the world due to the driving of both natural and human factors, and is dominated by abandonment rather than rehabilitation. Most of the studies focused on the spatiotemporal pattern of ecological cropland conversion in relation to the affecting factors at different scales, and a few integrated studies were made about the spatiotemporal variation in ecological cropland conversion at multiple scales. After cropland conversion, the vegetation succession showed a complicated spatiotemporal pattern due to comprehensive effects of many factors. The study focus of vegetation succession after cropland conversion showed the trends of: from structure analysis to function analysis of plant community, and from pattern analysis of succession processes to analysis of spatiotemporal variation of vegetation succession. However, it is lack in the study about the spatiotemporal variation, affecting factors, and mechanisms of vegetation succession after cropland conversion. Therefore, in the future, more attention should be paid on the multiple scale spatiotemporal variation of ecological cropland conversion and vegetation succession.

Relationships between species diversity and ecosystem functioning: A review.

LI Lu-jun^1,2; ZENG De-hui¹

2008, 27(11):  2010-2017 . 

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The unprecedented loss of species has motivated people to conduct considerable researches to describe the relationships between species diversity and ecosystem functioning and to reveal the mechanisms underlying. Based on the recent advances, some key issues on the relationships between species diversity and ecosystem functioning (such as productivity, stability, and invasion-resistance) in several representative experimental studies, including microcosm, Ecotron, Cedar Creek grassland experiment, and European BIODEPTH, as well as the applications of removal experiment in the studies of species diversity and ecosystem functioning, were summarized, and, based on the current understanding of the relationships between species diversity and ecosystem functioning, future challenges and trends were prospected, including the extension of experimental results from small temporal and spatial scales to larger temporal and spatial scales, the comprehensive consideration on the interactions of biotic and abiotic factors on species diversity and ecosystem functioning, and the effects of trophic levels and species coexistence mechanisms on the relationships between species diversity and ecosystem functioning.

Impacts of urbanization on distribution of birds: A review.

ZHANG Shu-ping

2008, 27(11):  2018-2023 . 

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With the rapid development of world economy, urbanization is being advanced with an unprecedented speed. Some characteristics of urban ecosystem, such as fragmentation and serious human disturbance, can impact the distribution of wild animals, and thus, the studies on urban biodiversity and the applications of ecological theories in urban planning are of significance in preserving urban ecosystem equilibrium. In this paper, the impacts of urbanization on the distribution of birds were reviewed from the perspectives of urbanization extent, patch characters of urban green space, and urban type. It was suggested that to study the effects of urban structural characters on the distribution of birds from local and landscape scales, and to strengthen the study at population level, would more benefit the establishment of reasonable plan for urban bird conservation.

Distribution pattern of winter wheat root system.

LIU Rong-hua¹; ZHU Zi-xi¹; FANG Wen-song¹; DENG Tian-hong²; ZHAO Guo-qiang²

2008, 27(11):  2024-2027 . 

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Based on the measured data from the winter wheat fields in Zhengzhou of Henan Province, the vertical distribution of root length density (RLD) and root mass density (RMD) were analyzed. The results showed that the roots of winter wheat were centralized in upper soil layer. At the depth of 0-50 cm, the RLD and RMD occupied 57.% and 66.% of the total; while at 50-100 cm, they were 23.4% and 18.7%, respectively. The variation of RLD and RMD with soil depth accorded with exponential function. Considering of the root distribution and its water absorption, the feasible depth of soil available water at planting for winter wheat in Zhengzhou was 100 cm.

Comparison of grassland biomass estimation models based on MODIS data.

QU Cui-ping^1,2; GUAN De-xin¹; WANG An-zhi¹; JIN Chang-jie¹; NI Pan^1,2; YUAN Feng-hui^1,2; ZHANG Xiao-jing^1,2

2008, 27(11):  2028-2032 . 

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To accurately estimate grassland biomass is of significance for the reasonable management of regional stock-raising and the evaluation of ecological benefit. Various vegetation indices and regression functions have been used in estimating grassland biomass by remote sensing data. Based on the field survey and MODIS data, and adopting the significant remote sensing-based vegetation indices including Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Modified Soil Adjusted Vegetation Index (MSAVI), three regression models (linear, power, and exponential functions) for each paired grassland biomass and vegetation index in Keerqinzuoyihou County, Inner Mongolia were established and compared. The results showed that grassland biomass could be well simulated by linear, power, and exponential functions, and exponential function performed best. Three vegetation indices (NDVI, EVI and MSAVI) had significant positive correlation with grassland biomass, and were suitable for the successful quantification of grassland biomass based on MODIS. MSAVI functioned most efficient with above-ground biomass (R²＝0.900), and the simulation of total biomass was more effective than that of above-ground grassland biomass by using linear function with NDVI and EVI.