Table of Content

08 January 2012, Volume 31 Issue 01

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Articles

Phytoplankton’s community structure and its relationships with water body N and P concentrations in Lihu Bay of Taihu Lake in winter.

2012, 31(01):  1-7. 

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Based on the investigation of phytoplankton and water body nutrient concentrations in the Lihu Bay of Taihu Lake in January 2010 and by using GIS technique, this paper analyzed the species composition, dominant species, abundance, spatial distribution, and diversity of the phytoplankton in the Bay in winter. A total of 27 genera of 7 phylums were identified, among which, Chlorophyta (12 species), Bacillariophyta (7 species), and Cryptomonas (3 species) occupied 44.44%, 25.93%, and 11.11% of the total, respectively. The dominant species were Cryptomonas erosa, C. ovata, Chroomonas acuta,and Microcystis aeruginisa. The Shannon diversity index (H) was 1.1, and the Pielou evenness (J) was 0.34 on average. The phytoplankton had a density of 1099.6×10⁴ ind·L^-1, in which, Cryptomonas dominated the spatial distribution of the phytoplankton. The highest phytoplankton abundance was found in the zone covering from Baojie Bridge to Xidi Lake, and the lowest value was in the north of the Xidi Lake. As compared with the winter in 2007, the phytoplankton abundance in winter 2010 increased remarkably, and the dominant species shifted from Chlorophyta to Cryptomonas. Further analyses revealed that water body phosphorus was the limiting factor of phytoplankton growth, and the variation of water body nitrogen/phosphorus ratio was the main reason for the increase of the phytoplankton in winter.

Biomass distribution of phytoplankton and bacterioplankton in coastal areas of Leizhou Peninsula in summer and related affecting factors.

2012, 31(01):  8-15. 

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In July 2010, a survey was conducted on the biomass spatial distribution of phytoplankton and bacterioplankton in the coastal waters of Leizhou Peninsula, with the related affecting factors analyzed. The phytoplankton biomass in the coastal waters in summer was 15.66-1114.92 mg·m^-3, with an average of 192.49 mg·m^-3, and the bacterioplankton biomass was 3.36-50.12 mg C·m^-3, with an average of 18.43 mg C·m^-3. No significant difference was observed in the horizontal distribution of phytoplankton biomass among different regions, but the horizontal distribution of bacterioplankton biomass had significant difference,being the greatest in western region,followed by in eastern, and in southern region.The biomass distribution of phytoplankton and bacterioplankton in surface water and in the bottom had no definite pattern and no significant difference. The biomass of phytoplankton and bacterioplankton was the greatest in near-shore stations, followed by in intermediate stations, and the least in far-shore stations, namely, decreasing from landward to seaward. The bacterioplankton biomass was significantly positively correlated with water temperature, pH, and silicate, and significantly negatively correlated with water salinity, TOC, and phosphate, whereas the phytoplankton biomass was significantly positively correlated with water pH and DO, and significantly negatively correlated with water salinity and TOC. There was a significant positive correlation between phytoplankton biomass and bacterioplankton biomass, implying the interactive regulation between them.

Plant resources investigation and hyperaccumulator screening in Xiangtan manganese mine area of Hunan Province, central-south China.

2012, 31(01):  16-22. 

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A sampling plot investigation was conducted on the plant resources in the Xiangtan manganese mine area of Hunan Province. In the study area, the plant resources were abundant, with 53 species belonging to 28 families. Most of the plant species were wild, and a few were cultivated. The majority of the plants were perennial,and the fewer were annual. Most plants were shrub and grass,and a few were tree. These results indicated that the current local communities were dominated by perennial shrub and grass, which were at the primary stage of succession towards subtropical evergreen broadleaved forest after the original plants were completely damaged by digging exploitation. The analysis on the Mn enrichment by the plant species showed that there was a significant difference in the Mn concentration between roots and stems or leaves. Most plant species had higher Mn concentration in their underground parts than in their aboveground parts, and only a few was in adverse. Moreover, different plant species had significant differences in their capability of enriching Mn. The Mn concentrations in Cyperus rotundus aboveground and underground parts were higher than 10000 mg·kg^-1(the critical concentration for hyperaccumulators), and the biological concentration factor (BCF) and translocation factor (TF) were larger than 1 (the assessment criteria of hyperaccumulators), indicating that C. rotundus had a super capability in enriching Mn. It was also found that the biomass of C. rotundus in medium and high Mn mine areas was 507.06 g·m^-2, which met the requirement of hyperaccumulators, i.e., hyperaccumulator should have high biomass, and suggested that C. rotundus could be the first selection of hyperaccumulator for the ecological restoration of moderately and highly Mn-polluted areas.

Classification, ordination, and succession of secondary forests in Xiaolongshan National Nature Reserve in west Qinling.

2012, 31(01):  23-29. 

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Based on the field investigation data and by using two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA), a quantitative classification and ordination of the secondary forest communities in the Xiaolongshan National Nature Reserve was conducted, and the spatial distribution patterns of the vegetation communities were studied from the species composition and the ecological relationships of plant communities and environment, aimed to understand the succession of secondary forests in the Reserve, and give a rational environmental explanation. According to TWINSPAN, the forest communities in the Reserve were classified into 12 types. The DCA ordination graph distinctly reflected the ecological significances of the ordination axes. The horizontal axis basically reflected the variation of humidity, which increased gradually from left to right, and the vertical axis basically reflected the temperature gradient, which decreased from down to up. The succession pattern of the secondary forests was in the sequence of Populus davidiana forest → P. davidiana + Betula platyphylla forest → Quercus aliena var. acuteserrata pure forest or mixed forest, with Q. aliena var. acuteserrata forest as the climax community in the process of natural succession.

Effects of soil water regime on leaf photosynthetic characteristics of slash pine (Pinus elliottii Engelm.)seedlings.

2012, 31(01):  30-37. 

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Four treatments (normal soil water condition, CK; light drought condition,T₁; water saturation condition, T₂; and submersion condition, T₃) were installed to study the responses in leaf photosynthesis and chlorophyll fluorescence parameters of slash pine (Pinus elliottii Engelm.) seedlings to different soil water regimes. Differences were observed in the responses of the leaf gas exchange parameters, water use efficiency (WUE), photosynthetic pigment contents, and chlorophyll fluorescence parameters to the soil water regimes. The photosynthetic pigment contents were the lowest in treatment T₃, and the net photosynthetic rate (P_n), electron transport rate (ETR), and quantum yield of PSII photochemistry (Φ_PSII) were lower in treatments T₂ and T₃, as compared with CK. The slash pine seedlings in treatmentT₃ still had a higher P_n than the other plant species that have high tolerance to inundation, indicating that the slash pine seedlings had high tolerance to inundation. In treatment T₁, the seedlings kept high WUE, low stomatal conductance (G_s), and low transpiration rate (T_r) against the drought stresses, while decreased P_n, potential efficiency of primary conversion energy of PSII (F_v/F_m),ETR, and Φ_PSII, though these parameters were still maintained at relatively normal level. The above results suggested that slash pine seedlings could not only tolerate water-logging, but also endure a certain degree of drought, and that slash pine could be a candidate species in re-vegetation of the Three Gorges Reservoir region.

Effects of enhanced UV-B radiation on physiological characteristics of Bryum argenteum.

2012, 31(01):  38-43. 

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Taking the biological soil crust (Bryum argenteum) broadly existed in the Tengger Desert of China as test object, this paper studied the effects of UV-B radiation on the photosynthesis, cell membrane integrality, water-soluble protein content, and antioxidant enzymes activities of B. argenteum under laboratory condition. UV-B radiation decreased the chlorophyll content, chlorophyll fluorescence parameters, water-soluble protein content, and antioxidant enzymes activities of B. argenteum significantly, with the decrements positively proportional to the radiation intensity, while increased the malondiadehyde and carotenoid contents, with the increments increased with increasing radiation intensity. These results indicated that enhanced UV-B radiation intensity caused a significant reduction in the photosynthetic rate, cell membrane damage, and disorder of antioxidant enzyme system, but the increase of the carotenoid content with increasing radiation intensity could be one of the self-protection mechanisms of B. argenteum in resisting UV-B stress.

Responses of leaf functional traits and nitrogen and phosphorus stoichiometry in Abies fabiri seedlings in Gongga Mountain to simulated nitrogen deposition.

2012, 31(01):  44-50. 

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Abies fabiri is one of the dominant conifers in the subalpine area of western Sichuan Province, Southwest China. Taking A. fabiri seedlings as test materials, this paper studied their leaf functional traits and N and P stoichiometry under effects of simulated nitrogen deposition. To simulate nitrogen deposition, ammonium nitrate solution (50 kg N·hm^-2·a^-1) was weekly sprayed over the growth season (from May to October) of 2009 and 2010. After the two growth seasons, the total biomass, leaf dry weigh, leaf mass ratio, leaf N and P concentrations, and leaf N:P ratio of the seedlings under ammonium nitrate spraying increased by 11.29%, 46.70%, 41.40%, 37.30%, 22.33% and 6.43%, respectively, while specific leaf area (SLA) decreased by 6.61%, as compared with the control. There existed significant differences in the leaf dry weigh, leaf mass ratio, leaf N concentration, and leaf N∶P ratio between ammonium nitrate spraying and the control, and the leaf dry weight had a strong linear correlation with leaf N concentration. The total biomass, leaf dry weight, leaf N and P concentrations, and leaf N∶P ratio of seedlings under ammonium nitrate spraying were higher in the second growth season than in the first growth season. This study demonstrated that nitrogen deposition promoted the leaf growth of A. fabiri seedlings significantly, and increased the leaf N and P concentrations and leaf N∶P ratio. However, the variation of leaf N∶P ratio under nitrogen supply suggested that the seedling growth was still limited by the shortage of N supply. It was suggested that A. fabiri seedlings had cumulative effect for N.

Characteristics of soil labile organic carbon in poplar plantations of different ages in coastal area of North Jiangsu.

2012, 31(01):  51-58. 

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To understand the characteristics of soil labile organic carbon and its correlations with soil physical and chemical properties in the poplar (Populus euramericana cv. San Martino) plantations of different ages in coastal area of North Jiangsu, five poplar plantations of 4-, 8-, 12-, 15-, and 20 years old were selected, with the total organic carbon (TOC), water-soluble organic carbon (WSOC), microbial biomass carbon (MBC), and physical and chemical properties in 0-10, 10-25, and 25-40 cm soil layers analyzed. In the five plantations, the contents of soil TOC, WSOC, and MBC all decreased with soil depth, and the soil TOC content had a trend of decreased after an initial increase with increasing plantation age, being the maximum in the 15 years old plantation and the minimum in the 4 years old plantation. Overall, the contents of soil WSOC and MBC had the same variation trend as soil TOC content, and the soil WSOC/TOC and MBC/TOC ratios increased with increasing plantation age. There was a significant correlation between soil WSOC and MBC, and the soil WSOC and MBC were significantly correlated with soil TOC, TN, C/N, pH, and bulk density but not correlated with soil total S and soil moisture. This study indicated that with the increasing age of the poplar plantations in the coastal area of North Jiangsu, soil labile organic carbon content had no definite variation pattern, which affected the plantations acting as a carbon sink to a certain extent.

Evaluation of ecosystem services function value of farmland shelterbelts in Shandong Province. 

2012, 31(01):  59-65. 

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Evaluation of farmland shelterbelt ecosystem services is of vital importance due to its practical application in regional economical development and ecological environment protection. In this study, the farmland eco-service function value of Shandong Province in 2001-2005 was evaluated by the methods of market price, opportunity cost, and shadow price. In 2001 and 2005, the total ecological service function value of the farmland ecosystem in the Province was 95.83×10⁸ and 124.97×10⁸ Yuan, respectively, and the ecological service function index value was in the order of soil conservation > crop yield increment > biodiversity protection > CO₂ fixation and O₂ release > air purification. The increment of the total ecological service was 7.29×10⁸ billion per year, among which, the increment value of soil conservation service was the largest (3.23×10⁸ Yuan), followed by that of soil protection (2.19×10⁸ Yuan), crop yield increment (1.25×10⁸ Yuan), biodiversity protection (5.60×10⁷ Yuan), CO₂ fixation and O₂ release (5.00×10⁶ Yuan), and air purification (1.00×10⁶ Yuan). Due to the tremendous ecological service function value of formlanl shelterbelt, the ecological service market compensation mechanism and the perfect ecological service function evaluation method should be established as early as possible, so as to transform farmland from an ecological type into an ecological and economical type.

Effects of exclosure and uncontrolled grazing on spatial heterogeneity of Stipa krylovii steppe vegetation.

2012, 31(01):  66-73. 

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The heterogeneity of plant community species composition is the main attribute of plant community dynamics. By using line transect and quadrat methods, and based on species frequency and power law, this paper analyzed the variations of plant community species composition and spatial heterogeneity in an Inner Mongolian Stipa krylovii steppe under exclosure and uncontrolled grazing conditions. Inside and outside of the exclosure, the plant species all presented a centralized distribution. In terms of functional groups, xerophytes and mesoxerophytes were widely distributed inside and outside of the enclosure. Perennial herbaceous species dominated in life form. More than 60% of the species spread their seeds by gravity. Gramineae, Liliaceae, Compositae, and Leguminosae had a comparative advantage. Under exclosure, species diversity increased while community heterogeneity decreased, suggesting that the degraded grassland due to grazing was changing better.

Effects of soil moisture on leaf gas exchange and chlorophyll fluorescence parameters of winter wheat during its late growth stage.

2012, 31(01):  74-80. 

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A plot experiment with rainproof installation was conducted to study the effects of different soil moisture regimes on the leaf gas exchange and chlorophyll fluorescence parameters of winter wheat during its late growth stage. Five treatments were installed, i.e., natural soil moisture regime (CK), soil water supply coefficient (K_w) of 0.8, 0.6, 0.4 and 0.2, respectively. The leaf chlorophyll content in K_w=0.6  was close to that in K_w=0.8, and significantly higher than that in other treatments (p<0.05). In K_w=0.6, the leaf stomatal conductance and transpiration rate were mildly inhibited, while the photosynthetic rate was higher than that in K_w=0.8. In K_w=0.2, the photosynthetic rate, stomatal conductance, and transpiration rate were the lowest. The stomatal limitation was the highest in K_w=0.4, followed by in K_w=0.2, and smallest in K_w=0.8. Treatment of K_w=0.4 had the highest apparent quantum efficiency. Overall, the light compensation point decreased with decreasing soil moisture content, but the light saturation point and the maximum photosynthetic rate were the highest in K_w=0.6, followed by in K_w=0.8, and lowest in K_w=0.2. The antenna transfer efficiency (F_v′/F_m′), electron transfer rate (ETR), actual quantum efficiency of PSII (Ф_PSII), and photochemical quenching (q_P) were the highest in K_w=0.6, followed by in K_w=0.8, and lowest in K_w=0.2. It was inferred that in K_w=0.2, the photosynthetic rate of winter wheat was mainly limited by non-stomatal limitation factors,whereas in K_w=0.4, the photosynthetic rate was mainly controlled by stomatal limitation factors.

Avoidance distances of four ungulates from roads in Kekexili and related protection suggestions.

2012, 31(01):  81-86. 

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The avoidance distance from road is the trade-off between resources availability and predation risk of wildlife. To provide protection strategies for wild ungulates, an investigation was conducted in June and August 2010 to study the avoidance distances of the ungulates Tibetan gazelle(Procapra picticaudata), Tibetan antelope (Pantholops hodgsonii), Kiang (Equus kiang), and wild yak (Bos grunniens) from Qinghai-Tibet Highway in Kekexili, and the effects of traffic flow on the avoidance distances of Tibetan gazelle and Tibetan antelope. The avoidance distances of the four ungulates decreased in the order of wild yak (999.00 m±304.17 m), Kiang (568.39 m±8323 m), Tibetan antelope (286.31 m±26.73 m), and Tibetan gazelle (176.97 m±14.47 m), and there existed significant differences among the four avoidance distances. Traffic flow had no effects on the avoidance distances of Tibetan gazelle and Tibetan antelope, which might be related to the low sensitivities of the two ungulates to the regular disturbance. It was suggested that the establishment of wildlife channels, limited human activities, and adjustment of the distances between roads would be the efficient ways to decrease the negative effects of road on wildlife.

Community structure and functional groups of soil macrofauna in urban green spaces of Yancheng City, Jiangsu Province in spring.

2012, 31(01):  87-92. 

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In the last ten-day of April 2011, an investigation was conducted on the soil macrofauna in five different urban green spaces (poplar plantation, park green space, nursery, lawn, and rapeseed field) in Yancheng City of Jiangsu Province, aimed to understand the community structure and functional groups of soil macrofauna in the City in spring. There existed significant differences in the macrofauna group number and abundance among different green spaces. The number and abundance of the functional groups followed as phytophage > saprozoic > camivorous. An obvious surface assembly phenomenon of soil macrofauna was observed. Green space type,soil layer, and their interaction had significant effects on the group number and abundance of soil macrofauna. Among the green spaces except lawn vs. rapeseed field and nursery vs. park green space, there were significant differences in the abundance frequency distribution of phytophage and non-phytophage. Hierarchical clustering and non-metric two-dimensional scaling ordination showed that the soil macrofauna communities were similar between lawn and rapeseed field, but differed between other green spaces.

Influence of microclimate on the growth, development, and reproduction of brown frog (Rana dybowskii).

2012, 31(01):  93-99. 

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From May 2009 to May 2010, an experiment with random group design was conducted to study the growth and development of brown frog (Rana dybowskii) under simulated enclosure understory environmental condition and under greenhouse increasing temperature condition. As compared with the condition in enclosure, the average air temperature, ground temperature, humidity, and effective accumulated temperature in greenhouse increased significantly. The brown frogs in greenhouse had a shortened development period, advanced sexual maturity, and increased proportion of 2-year-old sexually matured females. The breeding rates of female frogs in greenhouse and in enclosure were 93.1% and 76.0%, respectively. In greenhouse, the growth of brown frogs accelerated, and the body weight of 1- and 2-year-old frogs was (6.30 ± 2.62) g and (36.55 ± 11.79) g, being 85.5% and 56.6% higher than that in enclosure, respectively. The brown frogs in greenhouse ended their hibernation and began their foraging in advance, and stopped foraging and began hibernation in delay, with an extending growth period. Likewise, their average fecundity per nest increased. There was a significant positive correlation between the body weight and fecundity of brown frog (r=0.921, P<0.01).

Effects of di-(2-ethylhexyl) phthalate on the biochemical indices of green mussel (Perna viridis).

2012, 31(01):  100-105. 

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A laboratory experiment was carried out to study the variations of superoxide dismutase (SOD) and catalase (CAT) activities and malondialdehyde (MDA) content in the visceral mass and mantle of green mussel (Perna viridis) exposed to different concentrations (0, 0.38, 1.92, 9.60, and 48.00 mg·L^-1) of di-(2-ethylhexyl) phthalate (DEHP) for a long term, and the recovery of these indices after the stress released. During the exposure period, the SOD activity in the visceral mass had an initial significant increase (P<0.05) and followed by a gradual decrease, while the CAT activity was inhibited first but induced then, recovering to the level of the control after 15 days of exposure. The MDA content in the visceral mass increased significantly with increasing exposure time (P<0.05). In the early period of exposure, the SOD activity in the mantle of the P. viridis groups exposed to lower concentrations DEHP was inhibited but that of the groups exposed to higher concentrations DEHP was induced (P<0.05), while after 4 days of exposure, the SOD activity of all the groups recovered to the normal level. The MDA content in the mantle of all the groups increased significantly (P<0.05). During the releasing period, the SOD and CAT activities in the visceral mass of P. viridis exposed to 0.38 mg·L^-1 of DEHP recovered gradually to the normal level, but the MDA content increased. After 7 days of releasing, the SOD activity in the mantle of P. viridis exposed to all test concentrations (except 48.00 mg·L^-1) of DEHP recovered to the normal level, while the MDA content maintained at a stable level. The above results indicated that DEHP had no obvious effects on the enzymes of antioxidant defense systems in the visceral mass and mantle of P. viridis but could induce the lipid peroxidation damage in the 2 tissues, and this damage could not recover in a short term.

Effects of Pseudostellariae heterophylla continuous cropping on rhizosphere soil microorganisms. 

2012, 31(01):  106-111. 

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By adopting microbiological culture method and terminal restriction fragment length polymorphism (T-RFLP) technique, this paper analyzed the effects of Pseudostellariae heterophylla continuous cropping on the microbial community structure in the rhizosphere soil. Compared with the rotation system of P. heterophylla-rice-P. heterophylla, the P.heterophylla continuous cropping led to a significant decrease of the amounts of bacteria and aerobic nitrogen-fixing bacteria in rhizospheric soil, but increased the amounts of fungi, actinomycetes, and anaerobic cellulose-decomposing bacteria significantly. No significant change was observed in the amount of nitrifying bacteria. Under P.heterophylla continuous cropping, soil bacterial species (genus) had a slight decrease, in which, the pathogenic and nosogenetic bacteria species (genus) increased, and some Streptomyces genus (species) with antagonistic function were found. The fungi species (genus) had an increasing trend, but none of the plant pathogenic fungi species (genus) was observed.

ARDRA analysis of genetic diversity of rhizobia isolated from the nodules of leguminous plants in Lanping lead-zinc mine tailings of Yunnan Province, Southwest China. 

2012, 31(01):  112-118. 

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By the methods of 16S rDNA cloning, amplified ribosomal DNA restriction analysis (ARDRA), and sequence homology comparison, this paper studied the genetic diversity of rhizobia isolated from the nodules of leguminous plants in Lanping lead-zinc mining tailings of Yunnan. Sequence analysis revealed that among the 49 positive clones in the 16S rDNA library, 3 operational taxonomic units (OTUs) were identified, based on the similarity of 40% ARDRA banding profiles at the sampling sites where the nitrogen, Pb²⁺, Zn²⁺ contents were different, suggesting that the genetic diversity and distribution of rhizobia could be related to the soil nitrogen, Pb²⁺,and Zn²⁺ contents. Diverse phyla of the representative strains in the 16S rDNA library were belonged to the three phylogenetic branches of Rhizobium sp., Sinorhizobium sp., and Bradyrhizobium sp. The results suggested that there was a higher genetic diversity of rhizobia isolated from the nodules of leguminous plants in the Lanping lead-zinc mine tailings of Yunna.

Degradation of microcystin by Rhodopseudomonas palustras.

2012, 31(01):  119-123. 

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Taking Microcystis aeruginosa as test material, SPE-HPLC was adopted to study the degradation of microcystin-LR by Rhodopseudomonas palustras. Under the conditions of anaerobic, light intensity 2000 lx, 35 ℃, pH 7.0, carbon source sodium acetate, and initial concentration OD₆₈₀ of the bacilli being 0.325, R. palustras could degrade 36.5% and 78.7% of the microcystin-LR with an initial concentration 3 mg·L^-1 in 6 d and 12 d, respectively. These degradation conditions were basically the same environmental conditions of algal blooms, and hence, R. palustras could have practical value for removing microcystin-LR from the water body during algal blooms.

Effects of Scenedesmus obliquus density on the population dynamics of Brachionus calyciflorus from Xin’an River.

2012, 31(01):  124-130. 

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With 1.0×10⁶, 2.0×10⁶,4.0×10⁶, and 8.0×10⁶ cells·mL^-1 of Scenedesmus obliquus as the food of Brachionus calyciflorus, and by using population accumulative culture method and life table demographic approach, this paper studied the effects of S. obliquus density on the population dynamics of B. calyciflorus collected from the Tunxi section of Xin’an River at 25 ℃. The results showed that food concentration had significant effects on the population growth rate and resting egg production of B. calyciflorus. At lower food concentrations (≤4.0×10⁶ cells·mL^-1), the population growth rate and resting egg production of B. calyciflorus were lower and had no differences, while at high food concentration (8.0×10⁶ cells·mL^-1), both the population growth rate and the resting egg production were larger. Food concentration had no significant effects on the mixture rate and fertilization rate of B. calyciflorus. At food concentration 4.0×10⁶ cells·mL^-1, the net reproductive rate and generation time of B. calyciflorus were the highest and longest, respectively. The intrinsic rate of population increase of B. calyciflorus at food concentration 1.0×10⁶ cells·mL^-1 was the smallest, and the average lifespan and life expectancy at food concentration 8.0×10⁶ cells·mL^-1 were the longest.

Allelopathic effect of Microcystis aeruginosa on Microcystis wesenbergii.

2012, 31(01):  131-137. 

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By the methods of co-culture and cell-free filtrate addition, this paper studied the growth curves of Microcystis aeruginosa and Microcystis wesenbergii, and approached the allelopathy between them. The co-culture test revealed that there existed mutual inhibition effect between M. aeruginosa and M. wesenbergii. When the initial cell density of the two algae was higher than 0.5×10⁶ cells·mL^-1 and their mixed ratio was 1∶1,the growth of M. wesenbergii was suppressed significantly (P<0.05) due to the allelopathic effect of M. aeruginosa, and the growth of M. aeruginosa was slightly inhibited by M. wesenbergii. The cell-free filtrate of M. aeruginosa in its exponential phase inhibited the growth of M. wesenbergii, and, when the filtrate was added continuously into culture solution and the initial cell density of M. wesenbergii was less than 0.5×10⁶ cells·mL^-1, the growth of M. wesenbergii was suppressed significantly(P<0.01).

Environmental response characteristics of CO₂ flux above urban green space in Pearl River Delta.

2012, 31(01):  138-144. 

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The net ecosystem exchange (NEE) of CO₂ above urban green space is controlled by various environmental factors. To quantitatively analyze the environmental response of the NEE can provide valuable basis for the evaluation of carbon fixation effect of green space ecosystem and the optimization of urban green space distribution. Based on the CO₂ flux data of Dongguan Botanical Garden in 2009 and 2010 measured by eddy-covariance method, this paper analyzed the relationships between the NEE and the environmental factors (photosynthetic active radiation (PAR), soil temperature (T_s), saturation vapor pressure differential (VPD), precipitation, and land cover distribution). The results showed that the absolute value of NEE increased with increasing PAR when the PAR was less than the light saturation point (1500 μmol photons·m^-2·s^-1), but presented a decreasing trend when the PAR was higher than the light saturation point. The ecosystem respiration (R_eco) increased with rising T_s, and was more sensitive to the T_s when the temperature was low (the Q₁₀ of Lloyd-Taylor equation was 1.8 at 10 ℃), compared with that at high temperature (Q₁₀ was 1.43 at 30 ℃). The VPD could act on CO₂ exchange by affecting plant stomata conductance. When the VPD rose, both the CO₂ release and the CO₂ fixation increased. Precipitation had significant effect on the R_eco through increasing soil moisture content. After precipitation, the R_eco at 25 ℃ was 15.8% higher than that before precipitation. There was a wider green space in northeast and southwest directions around the observation station. When these directions were the main contribution areas, the absolute value of NEE was larger, indicating that increasing urban green space could improve urban carbon fixation effect.

Relationships of landform and vegetation characters with soil hydrophysical properties in a small watershed of Liupan Mountains, Northwest China.

2012, 31(01):  145-151. 

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Based on the investigation data from 107 sampling plots in a small watershed of Fenshuilinggou in the Liupan Mountains of Northwest China, and by using multivariate statistical analysis, this paper analyzed the relationships of landform and vegetation characters with soil hydrophysical properties in the watershed. Soil water-holding capacity, total porosity, capillary water-holding capacity, bulk density, volumetric fragment content, and non-capillary porosity were considered as the important soil hydrophysical parameters for classifying soil hydrophysical properties, and soil capillary water-holding capacity was a sensitive parameter. The sampling plots were classified into 3 groups, with great differences in soil hydrophysical properties and vegetation types. Group III had the best soil hydrophysical properties, which was covered by the secondary broad-leaved forests mainly composed of birch (Betula spp.) and poplar (Populus davidiana) and mostly located on the middle section of shady slopes. Group II had relatively good soil hydrophysical properties, which was covered by Larix principis-rupprechtii plantation. Group I had the worst soil hydrophysical properties, which was covered by the natural forests mainly composed of Pinus armandii or shrubs and mostly located on steep slopes. The soil porosity was controlled by landform and vegetation characters. The most important parameters of landform affecting the soil porosity were relative elevation, slope position, and aspect, and the most important vegetation parameters affecting the soil porosity were DBH, tree height, and shrub layer coverage.

Partial pressure of water body dissolved carbon dioxide in mainstream and Xiangxi bay of Three Gorges Reservoir area in autumn. 

2012, 31(01):  152-157. 

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In September 2009, a cruise investigation was conducted to study the partial pressure of water body dissolved carbon dioxide (pCO₂) in the mainstream and Xiangxi River of the Three Gorges Reservoir Area in autumn. The pCO₂ in the surface water of the mainstream and Xiangxi River was 920-1140 and 150-240 μatm, respectively. At the joint area of mainstream and distributaries, the pCO₂ had a minimum of 368 μatm in surface water, and increased markedly with increasing water depth, being the maximum (1300 μatm) at 10 m depth and keeping stable downward. The CO₂ flux of the mainstream and Xiangxi River was 83.7±14.1 and -4.74±1.15 mmol·m^-2·d^-1, respectively, indicating that the mainstream was a sink, while Xiangxi River was a source of CO₂. Therefore, when evaluating the influence of reservoir construction on the CO₂ flux in reservoir’s surrounding regions, it would be necessary not only considering the local basins, but also investigating the entire study area comprehensively.

Analysis of road network pattern and landscape fragmentation based on kernel density estimation. 

2012, 31(01):  158-164. 

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Landscape fragmentation resulting from the development of road network has become a hot issue in road ecology. To quantify the spatial pattern of road network and its cumulative effects on adjacent landscapes is essential for the assessment of ecological consequences of road construction.Taking the core area of Pearl River Delta in Guangdong Province of South China as a case and by using kernel density estimation (KDE) method and road density index, this paper approached to quantify the spatial pattern of road system and its correlations with landscape fragmentation. KDE method could effectively identify and collect the hot regions of high density road network. The analysis of road density index showed that there existed strong correlation between road density and landscape fragmentation. The combination of road density and KDE method could overcome the limitations of road density calculation based on administrative boundaries traditionally, providing a better quantitative tool to study the characteristics and landscape fragmentation of road network.

Estimation of carrying capacity of urban green space system based on landscape accessibility.

2012, 31(01):  165-171. 

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Taking the urban central area of Shunde District, Foshan City in Guangdong Province of South China as a case, and based on landscape accessibility analysis, the ecological service function grading ranges of urban green space system was estimated, and, in considering of block population density, the current service population and carrying capacity of urban green space system were also calculated. In the study area, the urban green space types and patch distribution were not homogeneous. Green space was mainly distributed in the middle and west, but less in the densely populated area of east and north. According to the differences in the ecological service function of different green space types, and by using cost weighted distance method, the green space service zone was divided into five grades, which comprehensively reflected the differences in spatial accessibility and the ecological service function of green space system.A majority of the current service population of urban green space system was mainly distributed in the areas of grades Ⅰto Ⅲ. The calculation of the appropriate population density of the study area based on the per capita green area standard showed that, compared with the service population of urban green space system, the current service population density of the urban green space system in the study area already exceeded the carrying capacity of the green space system.

Application of topsoil resources in ecological restoration of gentle slopes along Pengze-Hukou highway, Jiangxi Province.

2012, 31(01):  172-179. 

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Selecting five representative gentle slopes along the Pengze-Hukou highway in Jiangxi Province of China as experimental sites, topsoil was applied to carry out ecological restoration,and line transect method was adopted to investigate the plant growth on the slopes one year later.It was feasible to take advantage of topsoil resources on the ecological restoration of the highway’s gentle slopes. Satisfactory results were obtained by implementing all experimental designs,among which, covering the gentle slopes with 7-10 cm depth of topsoil and artificially broadcasting plant seeds made the plant community structure on the slopes reached the initial stage of succession, with higher Simpson diversity index (averagely 0.80) and Pielou evenness index (averagely 0.84) and significantly higher biomass accumulation (averagely 446 g·hm^-2) and woody importance value index (averagely 14.5), being an available approach for the stability and continuity of plant community structure on the gentle slopes.

Dynamic analysis of land use and ecosystem services value in Cheng-Yu Economic Zone,  Southwest China.

2012, 31(01):  180-186. 

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Cheng-Yu Economic Zone is an ecological barrier of the upper reaches of Yangtze River, but its eco-environment is fragile. It is of significance to maintain and improve the ecosystem services of the Zone. Based on the satellite images taken in 2000 and 2007, and with the help of RS and GIS techniques, this paper quantitatively analyzed the spatiotemporal variations of land use in the Zone, and by using modified ecosystem services value coefficient, evaluated the dynamic changes of land ecosystem services, aimed to understand the responses of the ecosystem services to land use change and to provide useful information for policy maker concerned with the sustainable development of the Zone. In 2000-2007, the constructive land showed the fastest increase (1044.5 km²), with an annual increasing rate 5.3%, forestland had the largest increase (2908.7 km²), with an annual increasing rate 0.5%, grassland, water body, and unused land decreased with an annual rate of -2.0%, -0.7%, and -2.9%, respectively, while cropland shrank largest (2388.9 km²), with an annual rate -0.3%. Owing to the land use change, the total land ecosystem services value had somewhat increase, with the total value increased from 318.84 billion Yuan in 2000 to 321.15 billion Yuan in 2007. The increase of the total value was mainly contributed to the conversion from other land use types to forestland and from cropland and grassland to other land use types, while the decrease of the ecosystem services function was mainly due to the conversion from forestland to other land use types. To maintain the land ecosystem services function and sustainable development of the Zone, it would be necessary to protect the land use types with high ecosystem services value (e.g, forestland and wetland).

Application of thermal dissipation sap flow measuring system in investigating bamboo transpiration: Problems and solutions.

2012, 31(01):  187-193. 

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Active transpiration is an important metabolic basis for the rapid growth of bamboo, and plays a key role in maintaining the ecosystem water cycle and water balance in forested areas. How to accurately estimate the transpired water of bamboo forest is a pressing methodological problem needed to be solved. At present, thermal dissipation sap flow measuring system (TDP) is widely used in the research of tree water physiology and forest hydrology, but less applied in bamboo forest. A few studies on the bamboo transpiration measured with TDP were reported, but the results were unconvincing, because of the lack of rigorous experimental verification of the method. The authors considered that the non-uniform thermal distribution caused by the structural heterogeneity of bamboo wall and by the large hallow in the culm center could be the major reason for the inaccuracy of the measurement of bamboo transpiration by using TDP which works based on the heat flux exchange principle. In this paper, an approach combining water-injection induced hydraulic pressure and sap flow changing device together with whole-plant container weighing method was suggested to verify the applicability of TDP in estimating bamboo water use. Considering the bamboo’s population structure and the lack of secondary growth in bamboo wall, it was proposed that bamboo performed a cross-culm compensation for hydraulic limitation in way of water allocation through rhizomatous interconnection, and bamboo transpiration was mainly affected by culm age rather than by culm form and size. Therefore, to analyze the age effect on bamboo transpiration and to investigate the water use patterns of bamboo forests with different planting densities could provide references for the effective stand design and related implementing measures for bamboo forest production and catchment water resource management.

Research advances in paraquat-resistance mechanisms of weeds.

2012, 31(01):  194-199. 

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The infestation of paraquat-resistant weeds can cause serious damage to food production, and indirectly increase environmental pollution. This paper reviewed the recent years’ research advances in the occurrence, development, and damage of paraquat-resistant weeds, and discussed the mechanisms of paraquat-resistant weeds, with the focus on the relationship between transporter and resistance, restriction and isolation, protective effect of antioxidant enzymes, influence of light on resistant mechanisms, and genetics of paraquat resistance. It was considered that there would be an outbreak risk of paraquat-resistant weeds in China in the future, and the strategies of delaying the occurrence of paraquat-resistant weeds were suggested.

Ectomycorrhizae-induced mitigation mechanisms against the damages of acid rain on plants: A review.

2012, 31(01):  200-206. 

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As a main body of terrestrial ecosystem, forest is a major receptor of acid rain pollution. Acid rain has severe impact on forest ecosystem. Ectomycorrhizal fungi symbiose with plant roots, and protect their hosts against various aggressions, including that from acid rain. Many of the macrofungi form symbiotic ectomycorrhizae with forest trees, playing an important role in maintaining the nutrient balance of the trees and protecting the trees against pathogens. This paper reviewed the research advances in the relationships between mycorrhizae and acid rain. Acid rain can inhibit and reduce ectomycorrhizal formation and vitality, whereas ectomycorrhizae can alleviate the damage of acid rain to host plants and improve the hosts’ tolerance against acid rain. The ectomycorrhizae-induced mitigation mechanisms against the acid rain stress on plants are: 1) physical shielding effect of ectomycorrhizal morphological structure, 2) promoting host plant nutrient uptake and increasing host plant acid-defense capability, 3) improving host plant enzyme activities and host plant viability, and 4) secreting organic acids or other substances.

Bioavailability of marine sediment-bound heavy metals to benthic invertebrates: A review.

2012, 31(01):  207-214. 

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Marine sediment is considered as the important sink for heavy metals, while benthic invertebrates can accumulate heavy metals mainly through sediment ingestion. The ingested heavy metals can be transferred through food chain and finally affect human health. This paper summarized the research advances on the bioavailability of marine sedimentary heavy metals to benthic invertebrates, including the uptake pathway for heavy metal assimilation and the sediment geochemical and biological factors of governing the bioavailability of heavy metals to benthic invertebrates. Further researches were suggested to focus on the influence of inshore eutrophication on the bioavailability of sediment-bound heavy metals, the physical digestion process in the gut of benthic invertebrates involved with the bioavailability of sediment-bound heavy metals, and the variations of sedimentary heavy metals bioavailability in the whole life history of marine benthic invertebrates.

Methods for forest eco-service value evaluation: A review. 

2012, 31(01):  215-221. 

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The significance of forest ecological benefits is increasingly emerging,and the scientists and governments in the world are paying attentions to the evaluation of forest eco-service value, which promotes the growing up of related methods. This paper summarized the research progress on the methodologies of evaluating forest eco-service value, and classified the related commonly used methods into three types,i.e., market-based methods, energy-accounting methods, and software model methods. The first two methods still have some limitations. They are deficient in checking the rationality of substitution method, ignore the multi-criteria in forest ecosystem management, lack of considering surrounding affecting factors, doubly count a variety of ecological values, and lose sight of the scarcity in eco-service value. To overcome these limitations, this paper introduced the features and superiorities of software GUMB, CITYgreen, and Invest. Based on the review, the research directions for China forest eco-service value evaluation in the future were put forward: 1) further explore the relationships between forest ecosystem structure and function, 2) improve the applicability of related foreign evaluation methods, and 3) undertake more studies on the feedback from eco-compensation.

Biomass models of poplar plantations in arid desert environment of China based on perpendicular vegetation index. 

2012, 31(01):  222-226. 

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Taking the poplar plantations in Karamay City of Xinjiang as a case, and by using the actual poplar plantation biomass data of 48 sampling plots as well as the Landsat TM data,this paper analyzed the correlations between remote sensing information and actual poplar plantation biomass data,aimed to accurately estimate the biomass of poplar plantation ecosystem in arid desert environment of China. The linear and exponential models of poplar plantation aboveground biomass were established on the basis of perpendicular vegetation index (PVI), and applied to compare the normalize difference vegetation index (NDVI) and ratio vegetation index (RVI). There existed significant correlations between the three vegetation indices (PVI, NDVI, and RVI) and poplar plantation aboveground biomass, and the exponential model (y=13.783e^0.0257x) based on PVI was the best one (with multiple correlation coefficient of 0.761) for estimating the poplar plantation biomass in arid desert environment.

Ecological risk assessment of five provinces around the Bohai Sea.

2012, 31(01):  227-234. 

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Ecological risk assessment is a hotspot arising in recent 20 years, being an integrated junction of geography, ecology, and environment risk evaluation. The study of ecological risk is helpful for understanding local ecological environment, reducing ecological risk, and finally improving the interactions between human beings and nature. Taking the Bohai rim, a typical region of sharp contradiction between population and land, as a case, this paper assessed the ecological risk of five provinces (municipalities) around the Bohai Sea by referring to USEPA framework of ecological risk and combining the methodologies of grading and ordering in relative risk method .Different materials and methods were applied in different steps of the assessment framework. For risk receptor analysis, the ecological endpoints were expressed in ecological capital loss, while the environmental vulnerability was calculated by principal component analysis and weighted layer stack methods according to the index system. Then, the structure vulnerability was evaluated by  landscape index approach based on land use data and vegetation patches data. In the study area, the typical regions with high integrated ecological risk were sea-land interaction belts, mountainous and hilly areas, and cities, while those with low ecological risk were mainly distributed in plains and some hills, where the topography was relatively gentle with low relief, water and heat conditions were favourable, vegetation was dense, and natural disasters frequency was relatively low. For the high risk areas, it would be critical for risk prevention.

Estimation of stock biomass and mortality parameters of oriental sucking barb (Garra orientalis) in Nujiang River of Sichuan Province, Southwest China. 

2012, 31(01):  235-240. 

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In October 2006-October 2008, a total of 136 specimens of oriental sucking barb (Garra orientalis) with body length 54-167 mm and body weight 3-114.6 g were collected from Nujiang River. The stock mass of the oriental sucking barb in the River was tentatively estimated by using length-based cohort analysis (LCA), and the Beverton-Holt dynamic model was developed to predict the population dynamics of the oriental sucking barb to support fishery management. The total mortality rate (Z) and the natural mortality rate (M) of the population were 0.511 and 0.238, and the fishing mortality rate (F) and current exploitation rate (E) were 0.273 and 0.534 per year, respectively. In 2006-2008, the average stock of the oriental sucking barb was 1.47×10⁴ kg, with 1.08×10⁶ individuals, and the initial stock was 1.87×10⁴ kg, with 1.38×10⁶ individuals. The analysis of related parameters and relative yield per recruit suggested that the oriental sucking barb in Nujiang River was in over-exploitation.Consequent conservative fishery strategy should be carried out to protect the resources of oriental sucking barb in Nujiang River.