Table of Content

08 October 2010, Volume 29 Issue 10

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Articles

Biomass, carbon sequestration and its potential of rubber plantations in Xishuangbanna, Southwest China.

2010, 29(10):  1887-1891. 

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In order to quantify the potential carbon (C) sink of the rubber plantations in Xishuangbanna and to understand the implication of the C sink to the regional C budget and future forest management, six age classes (5, 9, 14, 19, 23, and 26 years old) rubber plantations in suitable (low elevation, 550-600 m) and less suitable (high elevation, 950-1050 m) planting regions of Xishuangbanna were selected to estimate their biomass C stocks. In suitable planting region, 19-year-old plantation had the highest aboveground net primary productivity (16.22±3.47 t·hm^-2·a^-1), while in less suitable planting region, 23-year-old plantation had the highest one (8.65±3.46 t·hm^-2·a^-1). The maximum total aboveground biomass of the plantations in suitable and less suitable planting regions was 205.82 and 139.76 t·hm^-2, and the corresponding intrinsic rate of natural increase of biomass was 21% and 14%, respectively. The maximum total biomass carbon stock of the plantations in suitable and less suitable planting regions was 123.49 and 83.86 t C·hm^-2, respectively, being obviously lower than that (311.41±66.46 t C·hm^-2) of the local tropical seasonal rain forests. The total biomass carbon stock of the plantations in suitable planting region was slightly higher than the average value (121 t C·hm^-2) of the tropical forests in the world. By 2008, the total biomass carbon stock of the rubber plantations in Xishuangbanna was 16.54×10⁶ t C.

Eco-hydrological function of typical forest ecosystems in Three Gorges Reservoir area.

2010, 29(10):  1892-1900. 

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This paper studied the eco-hydrological function of typical forest ecosystems (mixed conifer and broadleaf forest ecosystem, evergreen broadleaved forest ecosystem, Phyllostachys pubescens forest ecosystem, and shrub ecosystem) in Three Gorges Reservoir area, taking cropland ecosystem as the control. The method of analytic hierarchy process (AHP) was applied to establish the eco-hydrological hierarchy function model, and integrative grades were employed to give evaluation. For the canopy layer, shrub had the best eco-hydrological function (score = 0.979), being 1.5-2 times as high as other forest stands. For litter layer, the best eco-hydrological function also occurred in shrub (score = 1), and the worst was in P. pubescens forest (0.422). For the soil layer, shrub still performed the optimal eco-hydrological function (score = 0.921), and P. pubescens forest was still the worst (0.313). The cropland was reconstructed from the shrub land. Though the cropland and the shrub land had the same site condition, the eco-hydrological function of cropland ecosystem descended by about 50% after eight years of crop management. The final integrative evaluation showed that the eco-hydrological function of the test ecosystems was in the order of shrub (score = 0.95) > mixed conifer-broadleaf forest (0.52) and evergreen broadleaved forest (0.53) > P. pubescens forest (0.37) > cropland (0.33), suggesting that in Three Gorges Reservoir area, shrub ecosystem had the optimal eco-hydrological function, and the P. pubescens forest ecosystem was the worst. The eco-hydrological function of forest ecosystems was 1.12-2.9 times as high as the cropland ecosystem.

Population structure and dynamic characteristics of Machilus chinensisin Nan'ao Island, Guangdong Province.

2010, 29(10):  1901-1906. 

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A field investigation was conducted at 6 sampling plots in Nan’ao Island of Guangdong Province to study the population structure and dynamic characteristics of Machilus chinensis. In each plot, the diameter at breast height (DBH) (or basal diameter if tree height <1.3 m) and height of each individual were measured. The field data were then analyzed from the aspects of age structure of population, static life table, survival analysis, and time series prediction. In Nan’ao Island, the age structure of M. chinensis population was shaped as an inverse “J”, i.e., more individuals at seedling and sapling stages, and less individuals with mid-size (DBH=8-20 cm) and big size (DBH >20 cm), characterized by a growing population. The survival curve of the population generally matched Deevey type Ⅲ, with the high mortality at seedling stage and lower mortality at big tree stage. The mortality and killing power curves showed similar trend, with one peak at age Ⅰ(seedlings of DBH=0-1 cm) and the other at age Ⅴ(mid-sized trees of DBH=12-16 cm). Age Ⅵ (DBH=16-20 cm) had the lowest mortality and the highest life expectancy. The survival rate of the population decreased monotonically, while the cumulative mortality rate curve increased monotonically. The mortality density and hazard rate curves showed the similar trends to the mortality and killing power curves, i.e., shocked at prophase and metaphase, and stabilized at anaphase. From the age Ⅷ (DBH=24-28 cm), the population gradually entered physiological decline phase. The time series prediction for the population in the coming 2, 5, and 8 years showed that M. chinensis population would have a rising tendency.

Community structure characteristics of endangered plant Prunus mongolica.

2010, 29(10):  1907-1911. 

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Through the investigation of species composition and ecological type, this paper studied the community structure characteristics of endangered plant Prunus mongolica. The results showed that P. mongolicahad a unitary community structure. A total of 42 species belonging to 23 families were collected, and most of them belonged to Gramineae, Compositae, Rosaceae, and Leguminosae. With the increase of altitude, the plant height and crown width of P. mongolica tended to be increased first and decreased then. There was a negative correlation between the community species richness and altitude. The comparison of β-diversity index showed that with increasing altitude, the similarity among the communities decreased and the species replacement rate increased, while the difference in the biodiversity between adjacent communities was not obvious and the species replacement rate became slow. Correlation analysis showed that the species richness of the community and the plant height of P. mongolica had close correlations with altitude, suggesting that altitude was the important factor leading to the changes of P. mongolica community.

Recent ten years spatiotemporal variation characteristics of vegetation index in Anhui Province.

2010, 29(10):  1912-1918. 

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Based on the 2000-2009 MODIS data, this paper analyzed the spatiotemporal variation of Normalized Difference Vegetation Index (NDVI) in Anhui Province. In the recent ten years, the annual average NDVI in the province increased, but had some differences in its spatial distribution, i.e., tended to be decreased in parts and increased in most regions. The monthly variation of the index presented weak double-peak pattern, with the maximum in August and the minimum in January. Based on the linear slope of the index in each season, the fastest increase was in spring, followed by in autumn, and the slowest in winter. In Dabie Mountain and southern mountainous area of Anhui Province, the interannual standard deviation and coefficient of variation of the index were smaller, indicating that the index had no significant change in mountainous area due to be less affected by outside interferences. Oppositely, the interannual standard deviation and coefficient of variation of the index in the grain production areas along Huaihe River were larger, which meant that human activities contributed more to the changes of the index.

Landscape fragmentation of evergreen broadleaved forest in East China.

2010, 29(10):  1919-1924. 

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Evergreen broadleaved forest (EBLF) is the zonal vegetation in East China. To monitor and evaluate the landscape fragmentation of EBLF is essential for the conservation, ecological restoration, and ecological management of the vegetation. In this paper, the identified forest types from NOAA-AVHRR NDVI data, combined with several calculated landscape metrics, were used to analyze the EBLF landscape fragmentation in East China. The results showed that the area of remnant EBLF in East China was only 35427 km², accounting for 5.9% of the whole region, and the average patch area and patch density were 8.55 km² and 0.69 per 100 km², respectively. The number of the patches smaller than 5 km² accounted for 61.2%, but their total area only occupied 5.75%. The same indices for those patches larger than 25 km² were 10% and 58%, respectively. The comparison of the individual provinces having EBLF distribution demonstrated that the landscape metrics, including patch area, mean patch size, patch density, edge density, landscape shape index, largest landscape index, and mean fractal dimension, were ranked in the order of Fujian > Zhejiang > Jiangxi > Anhui, while the metric of mean Euclidian nearest neighbor distance was completely inversed. All these results indicated that the EBLF in East China was in serious landscape fragmentation, giving greater impacts on the regional biodiversity conservation and sustainable development. It would be urgent to perform the ecological restoration, conservation, and management of EBLF in East China.

Soil factors limiting population regeneration of degenerated Haloxylon ammodendronin Gurbantonggut Desert.

2010, 29(10):  1925-1930. 

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In Gurbantonggut Desert, the population degeneration of Haloxylon ammodendron mainly occurs on the plain and small dunes (<5 m in height), while on the nearby large dunes (> 10 m in height), the plants can grow normally. In this paper, a comparative study was made on the age structure of H. ammodendron population, its seeds and seed germination characteristics under different salinity gradients, soil physical and chemical properties, and their effects on the population regeneration of H. ammodendron between degenerated and normal areas in small scale (under the conditions that the climatic factors and plant population age were similar). In degenerated area, H. ammodendron seedlings were lack, and the natural regeneration of H. ammodendron was hampered. There were significant differences in the hundred-seed weight with and without fruiting wings and the fruiting wing’s diameter of H. ammodendron among the three habitats (plain, small dunes, and large dunes). The seed germination rate of H.ammodendron had no significant difference under non salt-stress condition, but had significant difference under salt-stress condition and decreased with increasing salt concentration, suggesting that the limitation of the regeneration had no relationship with seed characteristics but close relationship with soil salinity. The soil physical and chemical properties in the three habitats were significantly different, and the soil electrical conductivity on the plain and small dunes was much greater than that on large dunes. The plant density of living H. ammodendron population was significantly negatively correlated with the electrical conductivity and water content of different soil layers, and the number of H. ammodendron seedlings (<40 cm in height) was significantly negatively correlated with the electrical conductivity of 0-30 cm soil layer. To sum up, high soil salinity severely decreased the plant density of H. ammodendronpopulation, restrained the seed germination and the seedling’s survival rate, and eventually led to the unhealthy natural regeneration of H. ammodendron.

Competition effect of Imperata cylindrica to Ageratina adenophora.

2010, 29(10):  1931-1936. 

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Invasive alien species may cause environmental degradation, biodiversity loss, food and water shortage, and high possibility and severity of natural disasters. It is a good way to replace invaded plant by utilizing valuable native species. In this study, same proportion of  native plant Imperatacylindrica and invasive plant Ageratina adenophora was mixed cultured, aimed to understand the competition effect of I. cylindrica to A. adenophora. There was a strong competition between these two plant species. I. cylindrica had a higher competitive ability than A. adenophora, being able to heavily suppress the growth of A. adenophora by shoot competition. Compared with A. adenophora, I. cylindrica could germinate faster, and its plant height and average leaf area were significantly higher. Mixed culturing I. cylindricaand A. adenophora could significantly restrain the growth and tillering of A. adenophora, resulting in the plant height, average leaf area, and chlorophyll content of A. adenophora being 49%, 72%, and 77% of those in monoculture, respectively. On the other hand, mixed culturing had no significant impact on I. cylindrica. In reverse, the tillering of I. cylindrica was promoted, with the tiller number being 132% of that in monoculture. The relative yield (RY) of I. cylindrica was significantly higher than that of A. adenophora, and the relative yield total (RYT) was lower than 1.0. With the prolonged time of mixed culturing, the relationships mentioned above became more obvious, suggesting that it would be a promising strategy to replace A. adenophora by I. cylindrica.

Factors affecting radial growth of female and male Pistacia chinensis trees.

2010, 29(10):  1937-1943. 

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By the methods of dendrochronology, this paper analyzed the effects of gender, tree size, and climate factors (temperature and precipitation) on the radial growth of dioecious Pistacia chinensis trees. Among the test affecting factors, tree size exhibited significant effects on the radial growth of P. chinensis(P<0.05), but gender did not (P>0.05). The growth rate of the individuals in different tree size classes differed with gender, e.g., the female trees in 10-15 cm DBH class had a significantly higher radial growth rate than the male trees in the same DBH class. The male and female trees showed similar responses to climate factors. Their radial growth rate was significantly positively related to the mean monthly minimum temperature in current March, mean temperature and mean monthly maximum temperature in current November, and monthly precipitation in current May, but significantly negatively related to the mean temperature and mean monthly maximum temperature in current May. There existed definite differences in the responses of the radial growth of the males and females to climate factors. The radial growth of the males was significantly positively related to the monthly minimum temperature in current April and significantly negatively related to the mean temperature and mean monthly maximum temperature in current July, while that of the females was significantly negatively related to mean temperature in current January.

Net carbon dioxide exchange of plant communities on degraded and restored alpine grasslands in headwater area of Three Rivers in China.

2010, 29(10):  1944-1949. 

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By the method of carbon assimilation chamber, we measured the photosynthetic rate, dark respiration rate, and net carbon dioxide (CO₂) exchange of plant communities on the natural grasslands at different degradation levels and the artificial grasslands having been planted for different years in the Maqin County of Qinghai Province. On the natural grasslands at different degradation levels, the photosynthetic rate and dark respiration rate of plant communities had a variation trend of moderately degraded grassland < heavily degraded grassland < extremely degraded grassland < non-degraded grassland. A certain amount of CO₂ was absorbed by the plant communities on the non-degraded, moderately degraded, and heavily degraded grasslands, while 1.20 μmol CO₂·m^-2·s^-1 was released from the extremely degraded grassland. After the artificial restoration of the extremely degraded grassland, the CO₂ release reduced. The mono-cultured Elymus nutans grassland established in 2000 and 2004 absorbed much more CO₂ than did the mixed cultivated grassland established in 2002 and 2005. With the increasing established year of mono-cultured and mixed cultivated grasslands, the net CO₂ absorption by the plant communities decreased. From the viewpoint of carbon management in Qinghai-Tibet Plateau, it was suggested that the moderately and heavily degraded alpine grasslands should be prevented from being further degraded, and the extremely degraded alpine grassland should be artificially restored in time to effectively increase the CO₂ absorption by plant community.

Effects of seed priming on biomass allocation and osmotic substance contents of sorghum (Sorghum bicolor L.) seedlings under salt stress.

2010, 29(10):  1950-1956. 

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Taking two sorghum hybridized combinations Tx623A×89-363 and Hei30A×Dalizao as test materials, 100 mmol·L^-1 NaCl solution was used to prime their seeds, and 0, 50, 100, and 150 mmol·L^-1NaCl solutions were designed for simulating salt stress. The effects of seed priming on the biomass allocation and the soluble substances, Na⁺ and K⁺ contents in different organs of the sorghum seedlings under salt stress were examined. Seed priming promoted the seedling’s growth, and increased the total amount of seedling’s dry matter, root biomass ratio, and root-shoot ratio in various degrees. Under the salt stress of 150 mmol NaCl·L^-1, the root biomass ratio, root-shoot ratio, and total amount of dry matter of primed Tx623A×89-363 were 5.4%, 6.2%, and 7.5% higher than those of the control, respectively, and the total amount of the dry matter of primed Hei30A×Dalizao was 10.9% higher than that of the control. Seed priming also increased the soluble sugar and proline contents of seedling’s leaves and roots significantly. Under the salt stress of 150 mmol NaCl ·L^-1, the soluble sugar and proline contents in primed Tx623A×89-363 seedling’s leaves and roots were 94% and 100%, and 85% and 202% higher than those of the control, and the contents of these two compounds in primed Hei30A×Dalizao were 48% and 71%, and 193%, 264% higher than those of the control, respectively. The Na⁺/K⁺ ratio in the seedling’s stems and leaves and seedling’s roots of Tx623A×89-363 and Hei30A×Dalizao was significantly reduced by priming. Under the salt stress of 150 mmol NaCl·L^-1, the Na⁺/K⁺ ratio in the seedling’s stems and leaves and seedling’s roots of Tx623A×89-363 was reduced by 16.7% and 20.6%, and that of Hei30A×Dalizao was reduced by 5.5% and 13.2%, respectively. The results proved that seed priming enhanced the adaptability of sorghum seedlings to salt stress to a certain extent. The effectiveness of seed priming differed with hybridized combinations, being better for the hybridized combination with weaker salt tolerance.

Water suitability for apple trees in dry-farming areas of Northwest China: Taking Tianshui City as an example.

2010, 29(10):  1957-1961. 

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Based on the  phenological observation data of apple trees from Tianshui Agro-meteorological Experiment Station in 2003-2009,  meteorological data from Maiji National Basic Meteorological Station in 1971-2009, and the apple’s yield data from Tianshui City in 1991-2009, a model of water suitability and water sufficient rate degree for apple trees was established to calculate the water requirement and water suitability degree of apple trees in their whole growth period, evaluate the water suitability for apple trees in the city, and analyze the correlations between the water suitability degree and apple yield in the city. The results showed that the water supply for apple trees in the city was under good condition, with the annual mean water suitability and water sufficient rate degree being 0.52 and 0.61, respectively. The water suitability degree in apple trees whole growth period decreased with time, being worse at vigorous growth stage but good at late growth stage. The water suitability degree decreased with ages at initial growth stage, varied little at vigorous growth stage, and increased at late growth stage. The correlation between the water suitability degree at initial and vigorous growth stages and apple yield was remarkable, but the correlation between the water suitability degree at late growth stage and apple yield was not significant. Using our established model could better evaluate the water suitability for apple trees in dry-farming areas of Northwest China, and provide scientific bases for zoning apple planting and irrigation.

Host selection of Meteorus pulchricornis and developmental performances of the parasitoid offspring.

2010, 29(10):  1962-1966. 

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Aimed to examine the prediction from the optimal diet model of classical foraging theory, i.e., female wasps prefer to lay eggs on most suitable hosts for the development of their offspring, a test experiment was conducted, taking Meteorus pulchricornisand its natural hosts Spodoptera litura and Mythimna separata larvae as test objects. To control the confounding effects of host body size and age, female M. pulchricornis was exposed to the larvae of the two host species with similar body size and same age, each at three levels. The results showed that M. pulchricornis preferred M. separate to S. litura in terms of the number of ovipositor-drilling and parasitization rate as measured by pupation rate. However, the offspring from S. litura was larger than that from M. separata as measured by the weight of cocoons and the hind tibia length of emerged adults. No significant difference was observed in the longevity of the M. pulchricornis adults from the two host species. A discussion was made on the mismatch between M. pulchricornis oviposition preference and its offspring developmental performances.

Allozyme analysis on genetic diversity of eight geographical populations of Oedaleus asiaticus in Inner Mongolia.

2010, 29(10):  1967-1972. 

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By using polyacrylamide gel electrophoresis of allozymes, this paper studied the genetic diversity among and within eight geographic populations of Oedaleus asiaticus in Inner Mongolia. Eight allozymes, including malate dehydrogenase (MDH), malic enzyme (ME), alcohol dehydrogenase (ADH), glutamate dehydrogenase (GDH), glutamic-oxaloacetic transaminase (GOT), isocitrate dehydrogenase (IDH), adenylatese (AK), and hexokinase (HK), were analyzed. Fourteen loci and twenty-five alleles were detected, with 7 loci polymorphic, and the overallproportion of polymorphic loci (P) was 42.86%. The average number of the alleles per locus (A) was 1.786, the expected heterozygosity H_e was 0.072, and the mean genetic distance was 0.069-0.235. The dendrogram was constructed by using UPGMA method, and the results indicated that the genetic distances were correlated with the geographical distances among the populations. Among the eight geographic populations of O. asiaticus, the coefficient of gene differentiation F_st was 0.086, and the number of migrants per generation (N_m) was 3.142. Our study indicated that there existed certain degree of genetic differentiation and gene flow among the eight geographic populations of O. asiaticus in Inner Mongolia.

Effects of water temperature on biochemical parameters of juvenile Chinese sturgeon (Acipenser sinensis) blood.

2010, 29(10):  1973-1978. 

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Chinese sturgeon (Acipenser sinensis) juveniles were cultured at the water temperature 15, 20, 25, and 30 ℃ for 66 days to study the effects of different water temperature on the blood biochemical parameters of the juveniles,  including total protein (TP), albumin (ALB), glucose (GLU), total cholesterol (TC), triglyceride (TGL), high density lipoprotein cholesterin (HDLC), total bilirubin (T-BIL), and urea. With the increase of water temperature, the concentrations of TP, ALB, GLU, TC, and HDLC in the blood all increased first and decreased then, and reached the maximum at 20 ℃, with the values being 15.98 g·L^-1, 5.6 g·L^-1, 4.85 mmol·L^-1, 2.44 mmol·L^-1, and 0.61 U·L^-1, respectively. The concentrations of blood TP, ALB, GLU, TC, and TGL reached the minimum at 30 ℃, and the values were 8.93 g·L^-1, 3.1 g·L^-1, 2.26 mmol·L^-1, 1.34 mmol·L^-1, and 3.35 mmol·L^-1, respectively. The T-BIL concentration also increased first and decreased then, with the maximum (2.50±0.84 mmol·L^-1) at 15 ℃ and the minimum (1.65±0.10 mmol·L^-1) at 25 ℃. Urea concentration decreased significantly with increasing water temperature, being the lowest (0.54±0.36 mmol·L^-1) at 30 ℃. The variation patterns of the blood biochemical parameters suggested that at 20 ℃, juvenile Chinese sturgeon had lower energy expenditure, being optimal for its growth.

Distribution patterns of phosphorus forms in suspended particulates and their relationships with chlorophyll a in Shidou-Bantou reservoir, Xiamen.

2010, 29(10):  1979-1984. 

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This paper studied the distribution patterns of phosphorus (P) forms in suspended particulates in Shidou-Bantou reservoir, Xiamen, and analyzed their relationships with the chlorophyll a content in the water body. In the suspended particulates in Shidou and Bantou sections, inorganic phosphorus (IP) was the major P form, occupying 77..9%-87.5% and 81.2%-88.1% of the total P, respectively. The abundance of different P forms was in the order of Fe/Al-P > Ca-P > OP, among which, the abundance of Fe/Al-P showed a gradient distribution, i.e., decreased from near-shore to the centre, while that of Ca-P had the least spatial differentiation. There existed significant correlations among the P forms, and IP, Fe/Al-P, and Ca-P were positively correlated while OP was negatively correlated with the chlorophyll a content of Cyanophyta and Chlorophyta.

Characteristics of zoobenthos community and potential ecological risk of heavy metals in urban rivers in Shanghai.

2010, 29(10):  1985-1992. 

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From October 2007 to October 2008, a monthly investigation was conducted on the community structure of zoobenthos in four urban rivers, including Wuchaogang River, Henggang River, Chaoyang River, and Caoyanghuanbang River, in Shanghai. A total of 20 zoobenthos species were recorded, among which, 14 species were of Mollusc, and 3 species were of Annelida. The zoobenthos in the four rivers had a low diversity, with the maximum value of Shannon index being 0.602. The diversity index of macrobenthos could objectively reflect the environmental quality of river body. In the four rivers, the concentrations of Pb, As, and Zn in Mollusc were 1.15, 0.32, and 0.23 times higher than the China’s national standard, respectively, and the concentrations of Cd, Cu, Pb, and Zn in sediments were all beyond the national standard. No correlations were observed between the heavy metals concentrations in Mollusc and sediments. The toxic-response factor (Eⁱ_r) showed that the potential ecological risk of the heavy metals was in the order of Cd>Pb>Cu>As>Zn>Cr, and the potential ecological risk index showed that the heavy metals pollution of the sediments in the four rivers was moderate.

Chemical forms and accumulation patterns of Cu in two sea grass species Thalassia hemprichii and Enhalus acoroides.

2010, 29(10):  1993-1997. 

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By the method of sequential extraction, this paper studied the Cu accumulation and its chemical forms in different parts of two tropical sea grass species Thalassia hemprichiiand Enhalus acoroidesunder different ambient Cu concentrations. For both T. hemprichii and E. acoroides, the Cuaccumulation was in the order of leaf > root > rhizome, suggesting that Cu was mainly accumulated in the leaves of the two sea grass species. HCl-extractable Cu was the predominant Cu form in leaf, indicating that the Cu in sea grass leaves was stably fixed and occurred as low toxicity copper complexes. On the other hand, NaCl-extractable Cu was the main Cu form in rhizome, suggesting that the Cu in rhizome was combined with protein and formed as relatively high activity copper complexes. In T. hemprichii root, acetic acid-extractable Cu was the main Cu form, suggesting that the Cu was mostly existed as insoluble copper phosphate, but in E. acoroidesroot, various Cu forms were found. Our results could provide a basis for studying the toxic mechanisms of heavy metals on sea grasses.

Effects of ammonium thiosulphate amendment on phytoremediation of mercury-polluted soil.

2010, 29(10):  1998-2002. 

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The low bioavailability of mercury (Hg) in Hg-polluted soil limits the application of phytoremediation. In this paper, a greenhouse pot experiment was conducted to study the effects of ammonium thiosulphate amendment on the Hg-bioavailability in soil, the Indian mustard biomass, and the Hg uptake by the plant. When the amended ammonium thosulphate was 1/12.5 of soil (W/W), the concentration of soil bioavailable Hg was the highest (0.51 mg·kg^-1), 12.7 times of the control. When the ammonium thosulphate was amended at a rate of 2 g·kg^-1, the dry weight of mustard root, stem, and leaf increased by 0.23, 0.98, and 1.22 g, and the Hg concentration in the root, stem and leaf was 1.96, 0.43, and 3.35 mg·kg^-1, being 8, 4, and 2 times of the control, respectively. Amendment of ammonium thiosulphate increased the leachate Hg concentration, with the maximum as high as 2487 ng·L^-1. Therefore, the amendment of ammonium thiosulphate to Hg-contaminated soil could increase the efficiency of phytoremediation, but on certain conditions, could also cause Hg-leaching into underground.

Influence of urea fertilization on the speciation distribution and phytoavailability of cadmium and lead in soil.

2010, 29(10):  2003-2009. 

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A pot experiment was conducted to study the influence of different urea fertilization levels (0, 100, 200, 400, and 800 mg·kg^-1) on the speciation distribution of Cd and Pb in rhizospheric and bulk soils and the Cd and Pb concentrations in wheat plants under single (Cd=25 mg·kg^-1, Pb=1000 mg·kg^-1) and combined (Cd+Pb=25+1000 mg·kg^-1) contamination of soil, aimed to provide basis for the control of heavy metals-polluted soils. The results showed that with increasing urea fertilization level, the Cd and Pb concentrations in different parts of wheat improved significantly. The promotion effect of urea fertilization on Cd and Pb uptake by wheat was closely correlated with the influence of urea fertilization on the speciation distribution of Cd and Pb in soil. Urea fertilization decreased soil pH, and increased the contents of soil exchangeable Cd and Pb, the most available speciation for plant uptake, being the main reason of urea fertilization promoted the phytoavailability of soil Cd and Pb. Compared with single contamination, the combined contamination of Cd and Pb restrained the Pb uptake but facilitated the Cd uptake by wheat.

Polycyclic aromatic hydrocarbons in Xihe River, Shenyang: Seasonal variation, sources, and ecological risk assessment.

2010, 29(10):  2010-2015. 

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Through the determination of the concentrations of polycyclic aromatichydrocarbons (PAHs) in Xihe River in different seasons, this paper analyzed the
temporal variation of PAHs, their sources, and possible ecological risk. In the water body of Xihe River, the concentrations of 16 PAHs ranged in 0.214-0.857μg·L^-1 (averaged 0.562 μg·L^-1) in June (summer), 0.195-0.633 μg·L^-1 (averaged 0.380 μg·L^-1) in September (autumn), and 0.122-0.486 μg·L^-1 (averaged 0.236 μg·L^-1) in November (winter), with that of benzo［a］pyren much higher than the guidance value provided by the environmental quality standards for surface water (GB 3838-2002). In June and September, the PAHs in Xihe River mostly came from oil, oil burning residue, and oil refined process. The preliminary assessment with quotient method showed that the benzo［a］pyren in the river had great ecological risk, which should be paid more attention.

Dynamic change of cropland percentage coverage in Taizhou region of Jiangsu Province.

2010, 29(10):  2016-2021. 

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To understand the change process and change pattern of cropland in Taizhou region of Jiangsu Province, the dynamic change of cropland percentage coverage (CPC) in the region from 1995 to 2006 was analyzed, based on the Landsat TM images of 1995, 2000, and 2006  by the method of neighborhood analysis. In 1995-2006, the cropland area in the region reduced continuously. The average relative amplitude of the variation of CPC decreased with increasing CPC from 0 to 80%, reached a minimum at 80%, and then increased with increasing CPC from 80% to 100%. The curves of pixel frequency-CPC in 1995, 2000, and 2006 showed similar mono-peaked patterns, but the peak values and their corresponding CPC decreased from 1995 to 2006. The 40%-80% CPC zones accounted for about 90% of the area change of the cropland in the study period. The area proportion of the 60%-80% CPC zones decreased significantly, while that of the 40%-60% CPC zones increased rapidly. The reduction rate of CPC was prone to be increased in the areas with relatively dense settlements and roads. The results showed that the stability and the area change rate of the cropland in the region were both closely related to local CPC.

Ecological benefits of golf course turf in North China and their value estimation.

2010, 29(10):  2022-2027. 

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Through tests and measurements, this paper analyzed the relationships between the leaf area and mowing characteristic of golf course turfs in North China, and further, established a relational model of turf leaf area index with different mowing height. There was a positive relationship between the leaf area index and the mowing height, and the blade width had greater effects on the leaf area index. Taking a golf course in Tianjin City as the case, a survey was made on the turf green quantity in its different components, and the ecological benefits of the golf course were calculated, based on the daily transpiration, O₂ release and CO₂ intake, and heat absorption per unit area Kentucky bluegrass. The annual transpiration of the golf course was 88119744.59 mol, annual O₂ release and CO₂ intake were 7830.67 t and 10771.66 t, respectively, and annual heat absorption for transpiration was 6903753.43 GJ. The economic benefits of the golf course estimated by environmental benefit evaluation method were 1102.59 ten thousand yuan for annual CO₂ intake, 313.23 ten thousand yuan for annual O₂ discharge, and 126760.58 ten thousand yuan for annual heat absorption for transpiration, with the total ecological value being 128176.95 ten thousand yuan.

Temperature-dependent sex determination in reptiles.

2010, 29(10):  2028-2034. 

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The sex determination mechanisms (SDMs) of vertebrate is one of the hotspots in the studies of evolutionary biology, being of significance in both ontogeny and sex ratio of natural population. According to the main causal agents of sex determination, the SDMs can be categorized into genotypic sex determination (GSD) and environmental sex determination (ESD), and the temperature-dependent sex determination (TSD) is the primary SDM in ESD. Most amniote vertebrates have a stable GSD mechanism, while reptiles have various kinds of SDMs, and even, the closely related species might have different mechanisms of SDMs. With reptiles as model systems, the researchers have made many studies on the SDMs of vertebrate. Here, we summarized the latest research on the TSD of reptiles, with the focus on the combined effects of temperature and hormone, the adaptive significance of TSD evolution, and the potential impacts of climate change on the TSD reptiles. Efforts were made to point out the priority in further TSD studies in reptiles.

Applications of endophytic bacteria in phytoremediation of heavy metals-contaminated soils.

2010, 29(10):  2035-2041. 

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Soil heavy metals contamination has become a worldwide environmental problem, posing great threats to human health and economic development. At present, phytoremediation is recognized as the most cost-effective and reliable remediation technique for heavy metals-contaminated soils. This technique mainly utilizes hyper-accumulator plants to extract and accumulate the contaminants from soil. How to improve the heavy metals resistance of plants and promote the plant growth dominates the phytoremediation efficiency. In this aspect, plant-endophytic bacteria symbiosis has its unique superiority. Endophytic bacteria have positive effects on the plant establishment and survival in heavy metals-contaminated soils via improving plant nutrient uptake, decreasing plant pathogens infection, affecting plant enzyme activities, secreting hormone, siderophores, and other organics, and as a consequence, enhancing the heavy metals accumulation by plants. This paper reviewed the recent studies on the screening and application of heavy metals-resistant endophytic bacteria, elucidated the mechanisms of endophytic bacteria-promoted plant growth, plant heavy metals resistance, and heavy metals translocation from root to shoot, and analyzed the processes and mechanisms of endophytic bacteria-enhanced phytoremediation. The potential applications of endophytic bacteria in phytoremediation of heavy metals-contaminated soils were proposed.

Molecular ecotoxicology of antibiotics, an emerging type of environmental contaminants: A review.

2010, 29(10):  2042-2048. 

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In recent decades, antibiotics have been widely used as the medicines for human and livestock. However, a large percentage of ingested antibiotics in living organisms are not metabolized but excreted and released as toxic contaminants, inducing their incremental residue in soil and aquatic environment, and resulting in adverse effects on living organisms and ecosystems. This paper summarized the research progress in molecular ecotoxicology of antibiotics, molecular mechanisms of antibiotics toxicity to living organisms and ecosystems, and ecotoxicological studies on molecular biomarkers of antibiotics, and summed up the new molecular diagnostic techniques applied in ecotoxicology. Some deficiencies of current molecular ecotoxicological diagnosis were pointed out, and the future study on the ecotoxicology of antibiotics was prospected.

Water quality criteria at home and abroad: Development trend and existed problems.

2010, 29(10):  2049-2056. 

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Ambient water quality criteria are the important basis for establishing water quality standards, and the significant part of scientific water quality management system. Aiming at the grim situation of  water pollution and the obvious differences in regional environment in China,  it’s urgent to establish water quality criteria fitting the characters of China water environment to supply theoretic bases for controlling and managing  water quality. This paper reviewed the research advances on the water quality criteria at home and abroad, with the focus on (1) the concept and connotation of ambient water quality criteria, (2) research history, status, development trend, and scientific issues of water quality criteria in American, European, and other countries, and (3) research emphasis and development trend in China, including regional water environment investigation, epidemiology, biotoxicology, and theories and methodologies in establishing ambient water quality criteria.

Cropland soil compaction: Its causes, influences, and improvement.

2010, 29(10):  2057-2064. 

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Soil compaction is one of the key barriers impacting cropland soil quality and crop growth, and the major concern in the researches of soil functioning and cropland ecosystem health. This paper reviewed the research progress related to the causes, influences, and improvement measures of soil compaction. In considering the affecting factors of soil compaction, farming system and water and fertilizer management should not be ignored, besides agricultural machinery. In addition, the influences of the above factors on soil compaction often changed temporally and spatially. Based on the comprehensive analysis of related researches, some problems to be solved in the research of soil compaction were discussed. It was considered that more attention should be paid on the researches of (1) genetic mechanisms of crop resistance to soil compaction in molecular level, (2) changing process of the interactions between crop and soil under soil compaction by using model and field visual assessment, and (3) improvement measures of soil compaction.

Research advances in assessment of forest naturalness.

2010, 29(10):  2065-2071. 

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Forest naturalness is an important indicator in describing forest status and in assessing forest landscape conservation, being widely used in nature-approximating forest management and vegetation restoration and reconstruction. Based on the analyses on the concepts, classifications, and evaluation methods of forest naturalness, this paper proposed that forest feature and human disturbance should be taken into account in the definition of forest naturalness, and an holistic approach combined with quantitative indictors and qualitative description should be considered in the assessment of forest naturalness based on the analysis of reference forest of potential natural vegetation. The standards of assessing forest naturalness at stand scale should be established to decide which attributes to be considered and how to weight these attributes according to different vegetation types, although there was a formed uniform methodology. The assessment of forest naturalness at landscape and regional scales might be more objective and practical for forest conservation and management than the assessment at stand scale, and thus, the naturalness attributes of different components of forest stands, related indictor system, and evaluation methodology at landscape and regional scales should be further studied.

Distribution pattern of diet zooplanktons in Lüsi fishing ground during nursing period of small yellow croaker.

2010, 29(10):  2072-2076. 

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Based on the investigation of oceanographic environment of Lüsi fishery (31.90°N-32.10°N, 121.70°E-121.95°E) in June 2008, this paper studied the species distribution pattern, dominant species, quantitative distribution, diversity, and other ecological parameters of diet zooplanktons in the fishing ground. A total of 31 diet zooplankton species (excluding planktonic larva and coelenterate) were observed, and planktonic copepods were dominant both in species number and in abundance. The total biomass of the zooplankton was averagely 845.54 mg·m^-3, with 895.58 mg·m^-3during spring tide and 795.49 mg·m^-3during neap tide. During spring tide, the biomass was higher in the north than in the south; while during neap tide, the biomass was the highest in the middle of the ground. In June, the dominant species were Labidocera euchaeta, Calanus sinicus, Paracalanus parvus, Acartia pacifica, Schmackeria poplesia, Peraclis reticulata, and Acanthomysis longirostris. During spring tide, both L. euchaeta and C. sinicus had the highest dominance of 0.19; during neap tide, the highest dominance of L. euchaetawas 0.40. In short, the biomass of the diet zooplanktons in Lüsi fishing ground was very rich, and the zooplanktoic community was composed of many dominant species, suggesting that the community structure of the diet organisms was stable, being able to provide a fine diet surrounding for the growth of juvenile small yellow croaker.

Effects of cadmium stress on Lonicera japonica leaf water content and plant microelement uptake.

2010, 29(10):  2077-2080. 

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Taking Lonicera japonica as test object, a soil culture experiment was conducted to study its leaf water content and plant microelement uptake under the stress of different concentration cadmium (Cd). With the increasing Cd concentration in soil, the leaf water content decreased after an initial increase. Under the stress of 100 and 200 mg Cd·kg^-1, the leaf water content was 70.4% and 65.3%, respectively, and had no significant difference from the control. Cd stress promoted the Fe uptake by roots, but decreased the Mn, Cu, and Zn uptake. Compared with the control, Cd stress decreased the leaf Cu content. The leaf Fe, Mn, and Zn contents increased under low concentration Cd stress, but decreased with increasing Cd concentration.

Effects of alternate drying-wetting on nitrogen removal efficiency of subsurface infiltration system.

2010, 29(10):  2081-2085. 

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Subsurface infiltration system (SIS) is an efficient and economic technique in treating decentralized wastewater, but its nitrogen removal is frequently problematic, due tothe complex inner environment of the system. In operating, intermittent running is a positive method to enhance the nitrogen removal of SIS. This paper studied the effects of alternate drying-wetting on the nitrogen removal efficiency of SIS in a laboratory experimental scale for domestic wastewater treatment. The experiment was conducted under the conditions of NH₄⁺-N concentration 30-37.5 mg·L^-1 and hydraulic loading 0.08 m³·m^-2·d^-1. With the increasing drying days, the substrate permeability and nitrifying bacterial quantity increased, specific volume and ammonifying bacterial quantity changed little, and denitrifying bacterial quantity declined. The ORP values at different depths fluctuated with the operation of drying-wetting. It was recommended that the drying-wetting ratio of SIS was 3:1 at the start-up period (20 days), and was 1:1 in the period of stable operation. In these cases, the removal rates of NH₄⁺-N and TN were 86.9% and 79.1%, respectively, and that of organic matter was consider
ably high, with the effluent meeting the standard of water quality for scenic environment use (GB/T 18921-2002).

Assessment of river ecosystem health in water source area of middle route of South-to-North Water Transfer.

2010, 29(10):  2086-2090. 

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From July 2007 to May 2008, an investigation was made on the hydrology, physical form, streamside zone, water quality, and benthic organisms in several streams that flow to the Danjiangkou Reservoir. By using a river health comprehensive assessment index, the river ecosystem health of the streams was assessed. In upstream reaches, the river ecosystem health was good; while in downstream reaches, the river ecosystem health was bad, because of the physical form change, increased autotrophic index, and decreased macro-benthic invertebrate diversity. It was suggested that to maintain the river ecosystem health of the streams flowing to the Danjiangkou Reservoir, the eco-environment in upstream reaches should be protected, and the destroyed physical form in middle reaches should be restored.