Table of Content

10 February 2014, Volume 33 Issue 2

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Effect of re-vegetation types on colonization and growth of biological soil crusts of dumping site in open pit coal mine of Heidaigou.

ZHAO Yang, ZHANG Peng**, HU Yi-gang, HUANG Lei, HU Rui, LIU Mei-ling

2014, 33(2):  269-275. 

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During August to September of 2012, a survey on coverage and thickness of biological soil crusts (BSCs) was carried on a dumping site in the open pit coal mine of Heidaigou in Inner Mongolia. Fifteen woody plots with a size of 10 m × 10 m, 45 herbage plots with a size of 1.0 m × 1.0 m and 150 biological soil crusts plots with a size of 0.2 m × 0.2 m were set under five re-vegetation types of arbor, arbor + shrub, arbor + herbage (Gramineae), arbor + herbage (Leguminosae) and abandoned farmland. The results showed that the total coverage of BSCs was more than 50% under each of the five re-vegetation types. The algae crust coverage under arbor and arbor + herbage (Leguminosae) re-getations was 56% and 43%, respectively, being higher than under other re-vegetation types. The moss crust coverage under arbor + herbage (Gramineae) re-vegetation was 34%, being higher than under other re-vegetation types. The thickness of BSCs under arbor + shrub re-vegetation was 0.55 cm, being higher than under other re-vegetation types. Vegetation restoration is beneficial to BSCs colonizing and growth at the dumping site of the open pit coal mine, and re-vegetation types and vegetation coverage significantly influence BSCs coverage and thickness.

Seasonal variations of soil nitrogen mineralization under different land-use types in a coastal area in northern Jiangsu, China.

CHEN Shu-xin1, WANG Guo-bing1, RUAN Hong-hua1**, YUE Zhen1, XU Chang-bai2, XU Ya-ming2

2014, 33(2):  276-282. 

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The variations of soil mineral N under four different land use types (i.e. poplar plantation, crop-poplar integrated system, grassland, and cropland) in a coastal area of northern Jiangsu were investigated by a closetop incubation method. The net N mineralization rate under each of the four land use types was higher in spring than in autumn, winter and summer. The net N mineralization rate decreased in order of poplar plantation, crop-poplar integrated system, cropland and grassland. Ammonium N and nitrate N showed obvious seasonal variations under the four land use types. The concentrations of ammonium N and nitrate N were generally higher in spring than in other three seasons. The soil mineral N decreased with increasing soil depth. In 10-25 cm soil layer, the soil mineral N concentration was significantly different between poplar plantation and croppoplar integrated system. In poplar plantation and grassland, the soil mineral N concentration was significantly different between 25-40 and 0-10, 10-25 cm soil layers. The concentration of soil mineral N was significantly higher in poplar plantation than in cropland and grassland in 0-10 cm soil layer.

Effect of planting density on temporal and spatial dynamics of soil respiration of rainfed maize field in Northeast China.

LU Guo-hong1, WEN Ri-hong1, ZHAO Qiu-shi2, LI Rong-ping1**, XIE Yan-bing1

2014, 33(2):  283-289. 

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The temporal and spatial dynamics of soil respiration were studied in maize fields with normal and low planting densities in Northeast China and the effects of soil temperature and air relative humidity on the soil respiration rate were analyzed. Results indicated that the diurnal variation of soil respiration showed a single-peak curve. However, the maximum peak appeared at 12:00-15:00 for maize normal planting density and 11:00-16:00 for maize low planting density. Soil respiration had lower rates in positions which were far from maize plants at the ecosystem level. Overall, soil respiration showed higher rates at maize normal planting density than at maize low planting density. The correlation coefficients between soil respiration and temperature or air relative humidity were different among different measuring positions and these correlation coefficients reached a significant level (P<0.01). Soil respiration was positively correlated with the soil temperature and negetively with air relative humidity.

Changes of understory plant community in Pinus tabuliformis plantation and associated environmental explanations.

LIU Hong-wen, CHENG Xiao-qin**, KANG Feng-feng

2014, 33(2):  290-295. 

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To better understand the relationship between the distribution of understory plants and environmental factors in Pinus tabuliformis plantation, the occurrence and distribution of understory plants were investigated on 42 plots in Songjiagou of Taiyue Mountain, Shanxi Province, China. The environmental factors controlling understory plant composition and diversity were quantitatively assessed by the method of canonical correspondence analysis (CCA). The results showed that: 1) 83 understory species belonging to 26 families and 72 genera were recorded on 42 plots. The number of species in the herb layer was more than 3 times of that in the shrub layer. 2) The results of CCA clearly reflected the relationship between the distribution of understory plants and environmental gradients. Forward variable selection showed that stand age, slope, slope aspect, canopy cover, total nitrogen and total potassium were important factors determining plant distribution in the herb layer, while stand age, slope aspect, slope, and total nitrogen were important in the shrub layer. 3) Habitat and biotic factors together explained 40.3% and 42.9% of variance in the distribution of herbaceous and shrub plants, respectively. Pure habitat factors exhibited a strong interpretation power for understory species distribution, suggesting that habitat factors might play an important role in the distribution variation of understory plants. The results of the study would provide a reference for scientific management, biological protection and sustainable utilization of P. tabuliformis plantation.

Soil microbial characteristics in the rhizosphere of Sonneratia caseolaris and S. apetala forests at different stand ages in Shenzhen Bay.

YANG Qiong1,2, TAM Fung-yee2,3, WU Yuan-ling1, XU Hua-lin1, ZAN Qi-jie2,4**

2014, 33(2):  296-302. 

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The present study examined the relationships between rhizosphere soil characteristics, microbial community and microbial activities in the forests artificially planted with two Sonneratia species at different stand ages (1-, 2-, 7-, 10- and 14-yearold for S. apetala and 1-, 4-, 7-, 10- and 14-yearold for S. caseolaris) in Futian National Nature Reserve, Shenzhen Bay. The rhizosphere soils in S. apetala and S. caseolaris forests at different stand ages were neutral or slightly acidic. The soil organic matter content increased with stand ages, but the total nitrogen (N) and total phosphorus (P) contents increased significantly only from 1- to 7-year-old stands and then decreased with ages. The temporal changes of the microbial biomass carbon, as well as the population sizes of bacteria, fungi and actinomycetes, were similar, with the maximum values in the 7-year-old forest. The microbial respiration rate in S. caseolaris was less than that in S. apetala at the same stand age. The microbial respiration rate increased with ages in S. caseolaris, but reached the peak value in the 7-year-old S. apetala forest. The canonical correlation analysis showed that the microbial biomass carbon and respiration rate in the rhizosphere were significantly correlated with soil organic matter content and pH.

Population distribution patterns and parasitic characteristics of Loranthus tanakae.

LIU Peng, WANG Xiao-an**, GUO Hua, OU YANG Hao-nan, ZHANG Liang, ZHANG Ya-juan

2014, 33(2):  303-309. 

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Loranthus tanakae is a deciduous shrub within the family Loranthaceae, and mostly parasitizes plants within the family Fagaceae. This study aimed to investigate the population growth and spatial distribution patterns of L. tanakae and its major host plant Quercus wutaishanica, and the parasitic behavior of L. tanakae in the Loess Plateau. The results showed that 42.1% (i.e. 358/851) of the sampled individuals of Q. wutaishanica were parasitized, with the number of parasites (L. tanakae) per host plant ranging from 1 to 20. Q. wutaishanica displayed a clumped pattern of spatial distribution at the scale of 0-60 m and a random pattern at the scale of ≥60 m, while L. tanakae showed a clumped pattern of spatial distribution at the scale of 0-100 m. 85.1% (i.e. 964/1112) of parasitic L. tanakae were observed within the 1/2 topheight of Q. wutaishanica, and the haustorium size of the hemiparasite was significantly associated with the circumference of the infested branch (r=0.713, P<0.01). Individuals of Q. wutaishanica with greater height and larger crowns were found to be more susceptible to the infection, and L. tanakae tended to parasitize the upper portions of the host plants.

 

Water-holding characteristics of leaf litter from different life-form plants in two habitats.

ZHANG Teng-da, TAO Jian-ping**, WANG Yu-ping

2014, 33(2):  310-315. 

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Water-holding characteristics of fresh leaf litter from three plant life-forms (tree, shrub and herb) were studied in two habitats (limestone and sandstone) in Chongqing. The relationship between water-holding capacity per unit area of leaf litter and immersion time (from 30 min to 24 h) was in line with the logarithmic function model. The waterholding rates of herb leaf litter were the largest in the fast water-holding stage in the two habitats, while the water-holding rates of tree and shrub leaf litter were larger with the increase of immersion time. Leaf litter from the limestone habitat had larger water-holding rates compared to the same leaf litter from the sandstone habitat. The maximum waterholding capacity per unit area was larger for tree, shrub and total species average in the limestone habitat than in the sandstone habitat. The natural moisture contents per unit area of leaf litter for shrub, tree and total species average, as well as the inner water-holding capacities of leaf litter of shrubs and the total species average, were significantly larger in the limestone habitat than in the sandstone habitat. The above-mentioned indicators for herb leaf litter were not significantly different between the two habitats. Overall, the water-holding rates and capacity of leaf litter from the limestone habitat were higher than those from the sandstone habitat, because of the adaptation of plants to different habitats.

Adaptability of an invasive plant Phytolacca americana to varied light environment.

DONG Zhou-yan, BAI Xin-fu**, ZHANG Jing-zi, HOU Yu-ping, BU Qing-mei

2014, 33(2):  316-320. 

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In this study, the adaptability of Phytolacca americana to light environment was analyzed based on the investigation of the photosynthetic performance indices, specific leaf area, calorific value, carbon and nitrogen use efficiency in P. americana under both shaded and unshaded environments. The results showed that the light saturation point, light compensation point and respiration rate all decreased significantly in the shaded P. americana, but the apparent quantum yield, maximum net photosynthetic rate and photosynthetic performance index showed no significant difference between the shaded and unshaded plants. In addition, the specific leaf area of the shaded P. americana was much larger, while the chlorophyll a/b ratio, the calorific value, carbon use efficiency and water use efficiency were significantly lower than those of the unshaded plants. Furthermore, the photosynthetic nitrogen use efficiency, mineral element use efficiency and light use efficiency in the shaded plants were significantly higher than those in the unshaded plants. The results suggest that P. americana can adjust its adaptability morphologically and physiologically to varied light environments, so as to make an efficient use of available radiation.

Comparision in thermotolerance over summer of seedlings among different provenances of Sorbus pohuashanensis (Hance) Hedl.

PENG Song1.2, MA Miao3, ZHENG Yong-qi1, ZHANG Chuan-hong1**

2014, 33(2):  321-327. 

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As an important tree species with high economic and ecological values, Sorbus pohuashanensis (Hance) Hedl. is naturally distributed in the alpine forest ecosystems in North China. Growth traits and physiological parameters in field were measured and heat tolerance of 1-year-old seedlings of six provenances were evaluated by subordinate function in order to select superior provenances at the earlier stage, which could well adapt to the habitats at low altitudes in North China. The results indicated that seedlings of the different provenances showed different adaptability to hot summer. Annual height increment of seedlings from Shandong Laoshan was the largest (34.99 cm), and annual ground diameter increment  of seedlings of Hebei Wuling  mountain provenance was the largest (6.90 mm). Net photosynthetic rate and transpiration rate of seedlings of Hebei Tuoliang moutain provenance were the highest (12.1 μmol CO₂·m^-2·s^-1 and 6.28 μmol H₂O·m^-2·s^-1, respectively), and those of Shanxi Pangquangou provenance were the lowest (8.03 μmol CO₂·m^-2·s^-1 and 4.39 μmol H₂O·m^-2·s^-1, respectively). Leaf damage of seedlings from Shanxi Pangquangou provenance was the greatest with the leaf damage index of 46.53%, while that from Shandong Taishan provenance was the least with the leaf damage index of 17.75%. Comprehensive evaluation results indicated that the 1-year-old seedlings originally coming from Shandong Province (Taishan and Laoshan) adapted better  to the conditions of hot summer in Beijing Plain than those from other provinces.

Sensitivity analyses of biochemical components of the spring tea Longjing 43 to meteorological factors.

LOU Wei-ping1**, JI Zong-wei2, WEN Hua-wei3

2014, 33(2):  328-334. 

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By using the support vector machine technology, the impacts of meteorological conditions on the biochemical component contents (e.g., tea polyphenol, amino acid, caffeine and total catechins) of the spring tea Longjing 43 were analyzed. The results showed that the support vector machine was useful and efficient for analyzing the relationships between meteorological factors and the tea biochemical components. The order of correlation coefficients for the tea biochemical components with the meteorological factors was not exactly in accordance with the order of the meteorological factors based on their sensitivities to the selected meteorological factors. The impacts of meteorological factors on the tea biochemical components could be classified into sensitive and insensitive sections. The biochemical components significantly changed in the sensitive section, but did not vary in the insensitive section.

Responses of ramet characteristics of wild vetiver population to density in western Guandong of China.

PENG Xue-mei1，2, LIU Jin-xiang2**, YANG Yun-fei3

2014, 33(2):  335-339. 

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A field experiment was conducted to study the responses of ramet characters of wild vetiver (Vetiveria zizanioides) population to planting density in western Guandong of China. On the 50 d (late October) and 240 d (next May) after planting, the ramet number of the wild vetiver population increased obviously. On the 270 d after planting, the ramet number under the highest planting density reached the maximum (821 ramets per square meter), which however  had no obvious inhibition effect on the increase of ramet number. On the 270 d (the beginning of June) after planting, the plot with a planting density of 80 ramets per square meter had significant differences in the numbers of no-jointed ramet, jointed ramet, and total ramet with the other plots. There was a significant linear correlation between the total biomass and the ramet number per square meter in all plots. The numbers of no-jointed ramet, jointed ramet, sexual ramet, and total ramet had significant positive power function relationships with the initial planting density. Though the planting density did not restrict the vetiver growth on the 270 d after planting, the increasing rate of ramet number was decreased obviously. The reproductive characteristics of the vetiver decided that the vetiver could still grow well at high planting density.

Semiochemical parsimony of two key floral volatiles to Helicoverpa armigera.

LI Yang-yang, WANG Jue, YUAN Guo-hui, GUO Xian-ru, LI Hui-ling, LI Wei-zheng**

2014, 33(2):  340-345. 

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To elucidate the parsimony of floral volatiles to Helicoverpa armigera, we determined the effects of two key floral volatiles, phenylacetaldehyde and benzyl acetate, on the ovipositional choice, sex pheromone trapping, and neonatal approaching behavior. The oviposition bioassay shows that the percent of eggs deposited by mated females on the gauze covered on the binary blend of phenylacetaldehyde and benzyl acetate did not differ from those covered on all the host leaves (hot pepper, tobacco, cotton, and maize) but tomato leaves, suggesting that these floral volatiles had fairly strong ovipositional attractiveness. The addition of floral attractant to H. armigera sex pheromone could enhance the field trap catch of H. armigera moths, and the trapping of other moth species, such as Argyrogramma agnate, Agrotis ypsilon, Spodoptera exigua, Ostrinia nubilalis, Cnaphalocrocis medinalis, and Hymenia re-curvalis,  was not influenced by the presence of H. armigera sex pheromone, indicating that the floral attractant had good compatibility with H. armigera sex pheromone. Additionally, the floral volatiles could enhance the perception of neonates to tobacco leaf discs. Taken together, floral volatiles have multiple ecological functions to H. armigera, and this semiochemical parsimony might be favored by natural selection.

Population dynamics of Chrysolina aeruginosa in Ningdong region of Ningxia and the related influencing factors.

ZHANG Da-zhi1**, ZHAO Na2, LI Yue-cheng2, MA Yan1, WANG Xu1, XIE Jia-cheng1, MA Cheng-li1, CHEN Hong-bin1

2014, 33(2):  346-351. 

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Chrysolina aeruginosa (Coleoptera, Chrysomelidae) is one of main pests of Artemisia ordosica. In recent years, this phytophagous beetle has spread rapidly throughout Northwest China, which has led to mass mortalities of A. ordosica. This pest has produced great damage to the local ecology. Three habitats of A. ordosica (siltyloam hilly land, mobile and semimobile sandy land, and manuallyfixed sandy land) in Ningdong region of Ningxia were selected as study sites to investigate the population dynamics and  vertical distribution of C. aeruginosa. The results showed that the average population densities of C. aeruginosa in three habitats were 10.54, 1155 and 8.53 individuals pear clump, respectively. The victimization rates of A. ordosica were 81.54%, 85.15% and 85.92%, respectively, but the population of C. aeruginosa had not significant difference in three habitats. All population curves showed a single peak and the largest population occurred in late July to midAugust in 2012 in the three habitats. The vertical distribution of C. aeruginosa was mainly in the canopy layer and middle layer (40-70 cm). There was a highly significant correlation between the population density of C. aeruginosa and its vertical distribution in different height ranges of A. ordosica. Correlation analysis showed that the population dynamics of C. aeruginosa were closely related to diameter and burgeon length of A. ordosica and the altitude. Based on principal component analysis and gray correlation analysis, population dynamics of C. aeruginosa was positively correlated with the mean temperature and increasing temperature could promote its population growth within a certain range.

Identifying predators of ground nests of birds in Kuankuoshui Nature Reserve, Guizhou, southwestern China.

WANG Jia-jia1, 2, YU Zhi-gang2, LI Zhu-mei2, JIANG Hong2, LIANG Wei1**

2014, 33(2):  352-357. 

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Nest predation is the primary cause of nest failure and leads to low or zero breeding success for most birds. From May to July, 2012, infrared cameras were used to identify predators of ground nests of birds in Kuankuoshui Nature Reserve, Guizhou, southwestern China. A total of 7 predation events were recorded for 15 natural ground nests, including 2 (28.6%) by Siberian Weasel (Mustela sibirica), 1 (14.3%) by Red-billed Blue Magpie (Urocissa erythrorhyncha), Magpie (Pica pica), Civet Cat (Paguma larvata), Edward’s Rat (Rattus edwardsi) and King Rat Snake (Elaphe carinata), respectively. Totally, 17 predation events were recorded for 22 artificial ground nests, including 11 (64.7%) predated by Civet Cat, 5 (29.4%) by Edward’s Rat and 1 (5.9%) by Red-billed Blue Magpie. Mammals were responsible for 83.3% of total predation events, and thought to be the main predators of ground nests of birds. Time of predation varied with different types of predators, i.e. mammal predation occurred mainly at night, while both predation events by birds and snakes were exclusively diurnal.

Habitat segragation between foraging and bed sites of Tianshan argali (Ovis ammon karelini) in central Tianshan Mountains in winter.

LI Ye1, YU Yu-qun2, SHI Lei1**

2014, 33(2):  358-364. 

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Habitat segragation between foraging and bed sites for Tianshan argali (Ovis ammon karelini) was studied in Gurenguoleng of central Tianshan Mountains, Xinjiang Uygur Autonomous Region, China. During December 2009 to January 2010, we totally investigated the Tianshan argali among 12 line transects along 5 ditches. Line transects were allocated from the bottom to the ridge of the mountain covering all typical vegetations in this region. In the field investigation, we observed 120 foraging and 114 bed sites for Tianshan argali with 13 ecological factors: elevation, slope, slope direction, slope location, landscape type, vegetation height, vegetation coverage, hiding level, distance from road, snow depth, snow cover, distance to human settlements and number of plant species. The results showed that there were no significant differences between foraging and bed sites for Tianshan argali among the factors of vegetation height, vegetation cover, and hiding cover level (P>0.05) in winter, but the differences of altitude, slope, distance to road, distance to human settlements, number of plant species, slope location and snow depth (P<0.01), snow cover, slope direction and landscape types (P<0.05) were significant between foraging and bed sites. We found that 5 essential ecological factors played important roles in distinguishing the foraging and bed sites, with a decreasing order of importance as snow depth, distance to road, elevation, slope, and vegetation height. Based on the mentioned ecological factor variables, the accurate rate for distinguishing the foraging and bed sites of Tianshan argali reached 95.1%. The results demonstrated that there was obvious habitat segragtion between foraging and bed sites for Tianshan argali to live in winter.

The photosynthetic activity of phytoplankton in Qiandao Lake in winter.

SHENG Hai-yan1,2, YU Zuo-ming2, LIU Ming-liang2, HE Jian-bo2, HAN Yi-cai2, ZHANG Yin-long1**

2014, 33(2):  365-372. 

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Qiandao Lake is one of China’s ten major reservoirs and the most important strategic source of drinking water in the Yangtze River Delta region. An investigation was conducted on the water quality and the community structure of phytoplankton at 8 sampling sites in Qiandao Lake of Southeast China in January 2010. The photosynthetic activity of phytoplankton was measured by Phyto-PAM (Pulse Amplitude Modulation) and Water-PAM. The water quality indicators were in accordance with the requirements of the water environmental function zones except TN. There was a stratification of water temperature, physical and chemical indicators in winter. The thermocline depth was between 25-40 m. Diatoms, cyanobacteria, green algae, cryptophyta, dinoflagellates, and golden algae were observed in winter. Dominant phytoplankton groups were Diatoms (Melosira and Cyclotella). They accounted for 60% of the total density. Chlorophyll a concentration varied from 1.4 to 5.7 μg·L^-1. The results suggested that the photosynthetic activity of phytoplankton was active in winter. Diatoms had the maximum photosynthetic activity, secondly cyanobacteria, and finally green algae. There were significant horizontal and vertical spatial differences in photosynthetic activity. The light saturation intensity of phytoplankton in Qiandao Lake ranged between 700-1000 μmol·s^-1·m^-2. The results also suggested that the high photosynthetic activity of diatoms relate to the outbreak of diatom bloom in Qiandao Lake in spring.

Secretion characteristics of two plants under hydroponic culture and its relationships with pollutant removal. 

HUANG Yong-fang1, YANG Qiu-yan1, ZHANG Tai-ping1,2**, HE Jin-tao3

2014, 33(2):  373-379. 

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Polluted river water and Hoagland nutrient solution were taken as the culture media for detecting secretion characteristics of two plants, Cyperus alternifolius and Canna indica, under hydroponic culture and its relationships with pollutant removal in this study. Both plants with no significant intraspecific differences in size and weight were cultured to observe the growth, to compare the root exudation, radial oxygen loss as well as their relationships with water purification by the two plants in the two culture media. C. indica had a significantly higher growth rate in the nutrient solution than in the polluted river water, while C. alternifolius showed no significant difference in both media. The amounts of root exudation per unit weight of plant were significantly different between the two plants in the two media. C. alternifolius exuded more per unit weight than C. indica in both solutions. Both plants exhibited greater secretion in polluted water than in the nutrient solution. The maximums of root secretion in the nutritional solution and polluted river water for C. alternifolius and C. indica were 2.89 and 34.76, and 1.28 and 1.82 mg·g^-1·d^-1, respectively. Radial oxygen loss (ROL) rate of C. alternifolius was significantly higher than that of C. indica in both solutions. Both plants showed higher ROL rates in polluted water than in the nutrient solution. For C. alternifolius, the highest ROL rate was 0.92 μmol O₂·h^-1·g^-1 (plant) or 6.69 μmol O₂·h^-1·g^-1 (root) in the polluted water; while the lowest was 0.20 μmol O₂·h^-1·g^-1 (plant) or 1.15 μmol O₂·h^-1·g^-1 (root) in the nutrient solution. After the adaptation period, the removal efficiencies of ammonia, TN, TP reached more than 90%, while COD removal was lower and fluctuated within a certain range. The amounts of COD removal per unit weight of C. alternifolius and C. indica reached 6.95±1.78 and 1.35±0.52 mg·g^-1, respectively, while the amounts of TP removal were the smallest, being only 0.28±0.06 and 0.06±0.02 mg·g^-1, respectively. The higher efficiencies of removal of pollutants COD, ammonia, TN and TP by C. alternifolius per unit weight than by Canna indica, were significantly associated with root secretion and radial oxygen loss. The results indicated that using C. alternifolius as floating bed plant in treating polluted river water could achieve a higher efficiency.

Effects of exogenous calcium on antioxidant system and proline metabolism of Potamogeton crispus L. leaves under mercury stress.

WU Juan, SHI Guo-xin**, XIA Hai-wei, HUANG Min, ZHENG Zhen-zhen, YANG Xiao-ke

2014, 33(2):  380-387. 

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Sterile seedlings of Potamogeton crispus L. were cultured by tissue culture technique, to investigate the effects of exogenous calcium (Ca) application on antioxidase system, soluble protein, antioxidant capacity (T-AOC), non-protein thiols (NP-SH), phytochelatins (PCs) and proline metabolism of leaves of the tested plants under Hg stress. The results showed that, Hg stress resulted in a serious imbalance of antioxidase system, such as restrained activities of catalase (CAT), ascorbate peroxidase (APX), and glutathion reductase (GR), while no obvious changes were observed in superoxide dismutase (SOD) and peroxides (POD) activities. Meanwhile, 25 mmol·L^-1 exogenous application of Ca markedly retarded the degradation of antioxidases and effectively enhanced SOD, POD, APX and GR activities in P. crispus. Hg treatment severely reduced the soluble protein content and T-AOC, as well as promoted a substantial accumulation of NP-SH and PCs. Application of exogenous Ca apparently reversed this situation and decreased the levels of NP-SH and PCs. Proline is an important osmolyte in aquatic plants on exposure against abiotic stresses. Addition of exogenous Ca increased proline accumulation significantly by activating pyrroline-5-carboxylate (P5CS) and rnithineδaminotransferase (OAT) activities. Our results demonstrated that Hg disturbed the intrinsic balance of antioxidant defense system in the tested plants. The supplement of exogenous Ca relieved the phytotoxicity of Hg to P. crispus by promoting the synthesis of soluble protein, increasing the activities of antioxidant enzymes and the contents of antioxidant substances, maintaining a high total antioxidant capacity and involving in regulation of a series of physiological and biochemical mechanisms, particularly proline metabolism.

Effects of NaCl stress on physiological characteristics of in vitro Curcuma aromatica plantlets.

YANG Chen, LIU Jian-fu**, WANG Ming-yuan, WANG Qi-zhi, TANG Yuan-jiang, ZHONG Shu-chun

2014, 33(2):  388-393. 

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A tissue culture experiment was conducted to investigate the changes of the growth, physiological characteristics and curcumin concentration of in vitro Curcuma aromatica plantlets under salt stress (0, 25, 50, 75, 100, 125 or 150 mmol·L^-1 of NaCl). Results showed that the concentrations of proline and malondialdedyde (MDA) of in vitro C. aromatica plantlets increased, while the concentrations of chlorophyll and carotenoid and the activities of superoxide dismutase (SOD) and catalase (CAT) decreased significantly under salt stress. No significant differences in the basal diameter, height and fresh weight were observed between the 25 mmol·L^-1 NaCl and control treatments, while those significantly decreased under over 50 mmol·L^-1 NaCl, suggesting that the plantlets of C. aromatica could tolerate 25-50 mmol·L^-1 NaCl stress. With the stress increasing, the soluble sugar concentration and peroxidase (POD) activity in C. aromatica increased in the early phase of stress and decreased subsequently, and the maximum was present under 75 mmol·L^-1 NaCl stress. The phenylalanine ammonia lyase (PAL) activity and curcumin concentration in leaves significantly improved under 50-100 mmol·L^-1 NaCl treatment, indicating that this salt stress promoted the formation of curcumin. Therefore, the range of 25-50 mmol·L^-1 NaCl benefits the growth of C. aromatica plantlets, while the 75 mmol·L^-1 NaCl increases the curcumin concentration significantly.

Screening, identification and physiological characteristics of an actinomycete strain against Rhizoctonia solani.

ZHANG Jing-yi1,2, ZHANG Qian-ru2**, XIANG Wen-hua1, WEI Shu-he2, MU Wen-yan2

2014, 33(2):  394-399. 

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By using dual culture technique, a strain of endophytic actinomycete named SCF-18 was screened out and isolated from Perinereis aibuhitensis collected from the Huanghai and Bohai Sea, and the bioactivities of the actinomycete against pathogenic fungi were determined. The strain SCF18 showed significantly antagonistic activities to both Rhizoctonia solani and Bipolaris sorokiniana, particularly more potent to R. solani with the maximum inhibition rate of 89.78%. The fermentation filtrate of SCF-18 could inhibit the growth of R. solani in a dosedepended manner. Furthermore, the fermentation filtrate of SCF-18 in 50% concentration showed the maximum growth inhibitory effects to R. solani and H. sativum with inhibition rates of 89.78% and 80.26%, respectively. The optimum growth condition for SCF-18 was at 30 ℃ with pH 7. The highest tolerance of salinity of SCF-18 was 5%. Based on the analysis of morphology, cultural characteristics, physiological and iochemical properties, and 16S rDNA sequencing, the SCF-18 was identified as Streptomyces lavendula. Our results suggest that the strain SCF-18 could be valuable in the biocontrol of R. solani.

Assessing ecological risks of heavy metals to marine organisms in the Jiulongjiang Estuary by species sensitivity distribution.

ZHAO Jia-yi1, DU Jian-guo2**, CHEN Bin2, LIU Zheng-hua2, LIN Jin-lan2,3, YU Wei-wei2, MA Zhi-yuan2, HU Wen-jia2

2014, 33(2):  400-407. 

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In the present work, a species sensitivity distribution (SSD) method was used to assess the ecological risk of common heavy metals to marine organisms. The ecological risk was characterized by potentially affected fraction (PAF) of species in relation to concentration of the toxic materials. According to the investigation data obtained at 21 stations in the Jiulongjiang Estuary in May, August and November, the PAFs of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) to marine organisms were calculated. The results showed that As had the highest PAF among the seven heavy metals at each station of the Jiulongjiang Estuary. Spatially, the multi-substance PAF (msPAF) in May was higher than in other months. Temporally, the msPAF of the Stations 1-7 (from the Xixi Stream to the Haimen Isle of the Jiulongjiang Estuary) suffered from heavier pollution. In particular, the pollution status of the Station 2 and Station 5 was the most serious among all the investigated stations.

Impact of heavy metal pollution on soil animal communities in abandoned coal mine area in Huainan City, Anhui Province.

SUN Xian-bin1, LI Yu-cheng2,3**

2014, 33(2):  408-414. 

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Abandoned mines are among the most significant pollution threats in Huainan City, Anhui Province. As the most sensitive environmental indicator, soil animals in those areas are worthy of investigation in ecological restoration. Eight sample plots were selected for studying the impact of heavy metal pollution on soil animal communities from two contaminated zones of coal mine waste rock pile and abandoned chemical plant in Datong, Huainan City. Results showed that a total of 2286 soil fauna individuals belonging to 24 groups, 8 classes, and 4 phyla were observed. The dominant groups were Collembola, Nematoda and Acarina, which accounted for 56.82% of the total groups, and the others were frequent or rare groups. Heavy metal pollution had a great influence on soil animals. As the pollution aggravates, the individual numbers, groups of soil animals presented a declining trend. Besides, the evenness, diversity and density-group index of community also declined. The dominance index gradually declined in the zone of coal mine waste rock pile while decreased first and then increased in the contaminated zone of abandoned chemical plant. Species diversity of soil animal communities decreased because of the heavy metal pollution, and the community structure tended to be simple. Heavy metal pollution showed a significant negative correlation with community structure index, but a poor correlation with soil organic matter and other nutrients. With the pollution level increasing, the surface gathering characteristics gradually disappeared.

Health risk assessment on heavy metals in dust of urban parks in Tianjin.

GUO Jin-ting1,2, ZHOU Jun3, HU Bei-bei1**, MENG Wei-qing1, WANG Zu-wei1, WANG Zhong-liang1

2014, 33(2):  415-420. 

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Samples of surface dust were collected from 41 representative urban parks in Tianjin. The health risk of heavy metals in surface dust was evaluated using human health risk assessment model established by U.S. EPA. The results showed that the pollution of heavy metals was serious. The average concentrations of Cu, Pb, Cr, Cd and Ni in the samples were 113.18, 63.32, 103.18, 1.14 and 40.58 mg·kg^-1 respectively, which all exceeded the background values in the soils of Tianjin. The direct ingestion of dust via hand-mouth contact behaviors was the major exposure pathway for health risk and the amount of chronic daily average exposure was in order of hand-mouth direct ingestion > dermal uptake > inhalation. The non-cancer risk of exposure was Cr > Pb > Cu > Ni > Cd, while the cancer risk of exposure was Ni > Cr > Cd. Non-cancer risk was higher for children than for adults. All the risks were lower than the average risk thresholds of the heavy metals, and would not cause noncarcinogenic or carcinogenic health hazard to human body, while its potential ecological hazard on children should be considered.

Pollution characteristics and ecological risk assessment of heavy metals in Haikou urban soils.

HE Yu-sheng**

2014, 33(2):  421-428. 

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The concentration, distribution, and speciation of heavy metals in urban soils of Haikou City were investigated. The mean concentrations of heavy metals Hg, As, Cd, Cu, Cr, Ni, Pb and Zn were 0.073, 3.82, 0.25, 26.7, 92.4, 52.5, 29.1 and 84.1 mg·kg^-1, respectively. In comparison with the background values, the enrichments of Hg, As, Cd, Cu, Cr, Ni, Pb and Zn in the soils of Haikou City were obvious, indicating a certain degree of heavy metal pollution. Cr, Ni, Cu, Cd and Zn were enriched in suburban areas, while Pb was enriched in roadside green belts and Hg was enriched in residential areas. Zn, As, Cr, Cu and Ni in the soils of Haikou were predominantly in residual fraction. Hg was mainly associated with strong organic-bound and residual fractions, while Pb was mainly presented as iron and/or manganese oxide-bound fractions. On the contrary, Cd existed mainly in bio-available fractions. The results of multiple-metals ecological risk assessment indicate that the heavy metal pollution in the soils of Haikou is at a relatively low level. However, Cd and Hg pollution deserves much more attention.

Environmental behavior of herbicide fomesafen in different soil types.

GUO Yu-lian1**, SONG Wei-feng2, LI Ming2

2014, 33(2):  429-432. 

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In this study, fomesafen residue and its leaching dynamics in three types of soil were clarified by high performance liquid chromatography (HPLC). When fomesafen was applied with the active ingredient at 1350 g·hm^-2, the halflives of degradation in the meadow, albic and black soils were 25.7-26.7, 16.9-19.3, and 26.7-30.1 days, respectively, which were consistent with the firstorder reaction kinetics model. Fomesafen leached gradually with its degradation in soil during 120 days, while most of it retained in the surface soil. In the albic soil, fomesafen leached to 30 cm after 30 days of application and the concentration of fomesafen in 10-30 cm soil reached the maximum after 60 days. In the meadow and black soils, the leaching depths were up to 30 cm after 5 days, and the concentrations of fomesafen in 10-30 cm soil reached the maximum after 14 days. These results indicate that fomesafen is hard to degrade in a soil with a high organic matter content, and the soil physical and chemical properties are main factors influencing fomesafen leaching. The residue toxicity of fomesafen on following rotation crops and its potential pollution to groundwater in the meadow soil and black soils were heavier than in the albic soil.

Stability and ecological effects of accumulated sand-belts along the oasis fringe in Hexi of Gansu.

CHANG Zhao-feng1,2,3**, ZHANG Jian-hui1,2,3, WANG Qiang-qiang1,2,3, ZHU Shu-juan1,2,3, ZHANG Da-biao1,2,3, FAN Bao-li1,2,3, TANG Jin-nian1,2,3, LIU Shi-zeng1,2,3

2014, 33(2):  433-439. 

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An accumulated sandbelt formed along the oasis edge, especially at the upwind places of the desert area in Gansu Hexi of China during the process of desert control in recent 60 years. The accumulated sand-belt is a byproduct of desertification combating through afforestation and barriers-setting. This paper analyzed the data (including wind velocity/direction) of 21 sites on the accumulated sandbelt to evaluate its stability and ecological effects. The results showed that the accumulated sandbelt is in a stable state. It plays a significant role in weakening wind and this effect is enhanced with the increase of wind velocity. The height of accumulated sand-belt is an important factor characterizing its windproof function. When the wind velocity is bigger than 2 m·s^-1, the windproof area in the downwind places is 20 times greater than the height of the accumulated sandbelt. When the wind velocity is bigger than 8 m·s^-1, the wind velocity on the top of the accumulated sand-belt is less than that in the upwind open areas. When the air flow reaches the windward slope, its energy is released and reduced by uplifting along the slope and diversion towards the two wings. Wind deflector reduces the velocity of the prevailing wind on the windward slope.

Impacts of road networks on species migration and landscape connectivity.

ZHOU Yuan1,2, ZHANG Qing-nian1**

2014, 33(2):  440-446. 

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Road networks fragmentize regional landscapes, block ecological processes and damage landscape functions. The effective evaluation of the ecological impact of roads provides valuable information for road route design, ecological restoration and landscape planning. Based on resistance surface concept and the minimal cost model, we calculated the landscape resistance, patch quality, accessibility of corridors, and landscape connectivity, and quantitatively evaluated the impact of road networks on species migration process. Results showed that roads increased the corridor length by 30% on average, the corridor curvature by 0.19. Roads also reduced the accessibility of ecological corridors by 90%, and the decrement was in linear relation to the minimal cost of the corridors, with a correlation coefficient of 0.76. Landscape connectivity was decreased by 30.8%, and the weaker the diffusion ability of corridors is, the more it will be affected by the roads. The proposed methods can be used to determine the key pattern of a specific ecological- process on the landscape scale, and provide information for the design of ecological corridors and quantitative analysis of landscape connectivity for ecological landscape planning.

Potential vegetation in China at the end of the 21st century based on CSCS and RegCM3 models.

CHE Yan-jun1, ZHAO Jun1**, SHI Yin-fang1, WANG Da-wei2

2014, 33(2):  447-454. 

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Potential vegetation, as an important part of the terrestrial ecosystem, could accurately reflect the local climate, and studying the distribution characters of potential vegetation would provide relevant references for the evaluation of ecological engineering. In this paper, the forecast data computed by RegCM3 model under scenario A2, was selected based on the Comprehensive Sequential Classification System (CSCS) to simulate the spatial distribution of potential vegetation in China from 2071 to 2100. The results indicated that all potential vegetation regions in China would change at different levels and directions. The temperate forest, which is the dominating part of Chinese potential vegetation, would change to colder and drier direction, so would tundra and alpine steppe. Frigid desert, tropical forest, and savanna all showed a moving trend to colder and wetter direction, the semi-desert vegetation mainly distributed in warm-humid regions, while steppe, temperate humid grassland, and warm desert showed a moving trend to warm-dry direction. Significant movement of spatial distribution center would occur for temperate humid grassland and warm desert. These results revealed the changes of potential vegetation in China for the 21st century, which can provide potential references for future national ecological construction strategy in the 21st century.

Vegetation cover change and its response to climatic factors using SPOT NDVI in Hedong of Gansu Province.

YANG Shang-wu, ZHANG Bo**

2014, 33(2):  455-461. 

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Spatio-temporal variations of the vegetation coverage and the correlation coefficient between Normalized Difference Vegetation Index (NDVI) and temperature/precipitation were analyzed based on SPOT NDVI and the yearly average temperature/annual precipitation data in Hedong region of Gansu Province during the period from 1998 to 2011 by using retrieval of vegetation cover, linear regression and correlation analysis. The results showed that the vegetation coverage was higher in the south and lower in the north, and a descending order of the vegetation coverage was Longnan Coteau > Gannan Plateau > Longdong Plateau > Longhzhong Plateau. In the recent 14 years (1998-2011), NDVI showed an increasing trend, with increment magnitudes at 0.05, 0.009, 0.039, and 0.023 per decade in Longnan Coteau, Gannan Plateau, Longdong Plateau, and Longhzhong Plateau, respectively. The vegetation coverage in 37.20% of total area was slightly changed, and approximately 59.75% kept stable, which indicated that the vegetation coverage in the study area had increased but was still at a relatively stable level. The correlations between NDVI and temperature/precipitation were spatially various in Hedong region. The correlation of NDVI with temperature was negative in 54.59% of the total area, and positive in the rest 45.41%, while its correlation with precipitation was negative for 12.14% of the total area, and positive for the other 87.86%. The area with positive correlation between NDVI and precipitation was much larger than that with positive correlation between NDVI and temperature, indicating that precipitation was the main factor affecting vegetation growth in the study region.

Eco-efficiency evaluation of urban complex ecosystem based on emergy and data envelopment analyses.

SUN Lu1,2, GENG Yong1**, LIU Zuo-xi1,2, XUE Bing1，2, LIU Zhe1,2, LIU Zhu1

2014, 33(2):  462-468. 

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Eco-efficiency is an effective tool to quantitatively analyze the input and output relation of social, environmental and economic perspectives of one ecosystem. It plays a key role to evaluate the sustainable development level of an urban ecosystem. By combining emergy analysis and data envelopment analysis (DEA) methods, this study proposes innovative emergy-based indicators and one new DEAbased model to measure the overall eco-efficiency of one urban ecosystem by employing a case study on Shenyang. Both emergy flows and eco-efficiency were calculated in order to assess the sustainable development levels from regional resources, environment, and economy perspectives. The results show that during the period of 2000 to 2010, the eco-efficiency of Shenyang had gradually increased. Emergy yield ratio first dropped a little bit, and then increased steadily. Environmental loading ratio rose significantly, showing an increasing resource pressure on Shenyang during its growth period. In order to improve its sustainable development, local governments should raise several appropriate policies, including optimizing energy-use structure, improving non-renewable resource use efficiency, and promoting waste recycling.

Eco-risk assessment of land use in Tianjin City.

XIAO Lin, TIAN Guang-jin**

2014, 33(2):  469-476. 

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This paper formulated land use eco-risk index at the landscape scale based on Tianjin’s land use dynamics from 1990 to 2005, then analyzed spatiotemporal differentiation characteristics of Tianjin’s land use eco-risk and its response to land use change by means of spatial statistics method and elasticity theory. The results indicated that changes in land use structure and quantity were complex. Transitions from both cropland and water to construction land were the main forms of land use change, as is prominently shown by the slump in cropland and surge in construction land. Land use eco-risk exhibited significant spatiotemporal variations. With great expansion of construction land, high ecorisk areas rose while low eco-risk areas decreased. Eco-risk areas at five levels had tended to be consistent by 2005. The eco-risk level was higher in downtown while lower in suburb regions, appearing as a ring-laminar layout on the whole. The land use eco-risk intensity in northern Jixian County and the eastern coastal zone was notably lower than the other regions. The transformation and mergence of different land use types caused the increasing spatial correlation distance of eco-risk index. The spatial correlation of land use eco-risk was significantly positive, besides the fact that its global and local spatial differentiation kept expanding. The response elasticity of eco-risk to land use change varied spatiotemporally, which was most highly positive in both Jixian County and Baodi District while the lowest in both inner city and Hangu District. As the land use ecorisk increased, its response elasticity to land use change showed a reverse development. The factors influencing land use eco-risk became more diversified.

Urbanization spatial expansion and regional landscape ecological risk of Yantai City.

ZHOU Di1,2, SHI Ping1**, WU Xiao-qing1, MA Jin-wei3, LIANG Shou-zhen4

2014, 33(2):  477-485. 

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By methods of remote sensing, GIS and mathematical statistics, together with urbanization intensity index, the spatialtemporal evolution characteristics of urbanization expansion of a coastal city, Yantai from 1974 to 2009 were studied. Meanwhile, based on landscape pattern metrics and ecological risk index, we studied the landscape pattern dynamic changes and spatial characteristics of landscape ecological risk during 1990-2009 under condition of urban expansion. The results showed that the area of urban land increased by 189.77 km² during 1974-2009 and the average annual expansion area was 5.42 km². The urbanization intensity index during 2004-2009 was 3.92 times of that during 1974-1990. The most significant changes of land uses were urban land and farmland. The changes of landscape pattern metrics for land use patterns indicated that the intensity of human activities was increasing gradually in this period. The landscape ecological risk pattern of Yantai City appeared as a circle distribution along the coastline. The farther the distance to the coastline, the smaller the ecological risk index was. The ratio of high ecological risk and subhigh ecological risk zones of the study case in 2009 was 2.23 times of that in 1990. A significant linear relationship of urbanization intensity index and regional ecological risk was observed in the study.

Research progresses in the effect of biochar on soil-environmental behaviors of pollutants.

SHI Hong-lei, ZHOU Qi-xing**

2014, 33(2):  486-494. 

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In recent years, biochar has become a research hotspot in agriculture, ecological remediation and environmental protection. It is generally believed that biochar can improve the soil quality, increase soil carbon sequestration, reduce atmospheric CO₂ concentrations, and remediate the polluted environment. After a large amount of utilization, biochar may change the property of soils and affect environmental behaviors and fate of heavy metals and organic pollutants in soil. In this review, the effects of biochar on adsorptiondesorption, species transformation, and migration behaviors of heavy metals in soilplant systems, as well as on adsorption, volatilization, other environmental behaviors and bioavailability of organic pollutants were summarized. Accordingly, some current problems such as environmental risks of biochar application were analyzed, and future research directions were prospected in terms of transformation and fate, long-term environmental effects and application direction of biochar.

Responses and mechanisms of forest soil respiration to nitrogen and sulfur deposition.

XIAO Sheng-sheng1,2, HU Jian-min1,2**, HE Yue-ling1, WANG Bang-wen1,2, PENG Qin3

2014, 33(2):  495-501. 

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The increased nitrogen (N) availability and soil acidification are two important ecological processes undergoing in most terrestrial ecosystems in the background of N deposition and sulfur (S) deposition. The two processes and their coupling actions obviously disturb soil respiration, further exterting important influnces on the carbon budget in forest ecosystems. Here we reviewed the effects and underlying mechanisms of N deposition and S deposition on soil respiration in forest ecosystems, analyzed the coupling effects of N deposition and S deposition, and proposed the main research directions in this field in the future.

Effects of forest fire on soil property and greenhouse gas flux.

REN Le1, MA Xiu-zhi2**, LI Chang-sheng3

2014, 33(2):  502-509. 

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Fire is one of the most important disturbance factors in forest ecosystems. Forest fires destroy forest resources and cause greenhouse gases emission from soil to atmosphere. At the same time, forest fires can affect soil physical, chemical and microbial properties, and consequently the fluxes of main greenhouse gases between soil and atmosphere. In this paper, we briefly reviewed the effects of different fire intensities on soil physical properties (such as soil structure, soil density, field water holding capacity and soil gross porosity), soil chemical properties (such as pH, nutrient contents), and soil microbial properties (such as microbial community structure, and microbial biomass C and N). We summarized the variations of soil CO₂, CH₄, and N₂O fluxes after different fire intensities and different time intervals, especially in the permafrost areas which are sensitive to global warming. The charcoal could be produced in forest fire under the condition of high temperature and less oxygen. We also summarized management methods for biochar in burned areas such as cleaning or burial, and their effects on soil properties and greenhouse gases fluxes. Finally, some problems unresolved in the research at present are identified, and the perspectives for further study are also proposed.

A review of influencing factors on latex yield of Hevea brasiliensis.

LI Guo-yao1, WANG Quan-bao2, LI Yu-ying1, ZHOU Shuang-xi3, YU Hai-ying4**

2014, 33(2):  510-517. 

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Latex from the rubber tree (Hevea brasiliensis) is a major source of natural rubber; however, the latex yield is limited by numerous factors. This study summarized the effects of climatic factors, soil nutrients, common diseases, tapping systems and techniques, clonal variety, and plantation management on the latex yield.  Temperature, precipitation and solar radiation are the three major climatic factors affecting latex yield; furthermore, these three factors have an additive effect on yield. The soil nutrients, i.e., nitrogen, potassium, phosphorus, and magnesium, have great effects on latex production. These nutrients can affect the rubber formation and latex flow through influencing the photosynthesis and mechanical stability. In addition, diseases and pests, tapping system and technology, rubber tree varieties, tree age, and management of rubber plantation all affect the latex yield. By analyzing the above factors and mechanisms synthetically, this study provides a theoretical reference for scientific research and practice of rubber production.

The response of dissolved organic carbon in freshwater ecosystems to global change: A review.

HUANG Wei1, RUAN Hong-hua1**, XU Zi-kun2

2014, 33(2):  518-524. 

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Dissolved organic carbon (DOC) in freshwater is an important component of the global carbon cycle, and is also carbon and energy source for heterotrophs in freshwater. The response of freshwater DOC to global change will affect the size of global carbon sink, and structure and function of freshwater ecosystems. We reviewed the influence of global change on freshwater DOC, and the feedback of freshwater DOC dynamics to climate change. We pointed out that interactions among global change factors affected freshwater DOC, and the influencing degrees of global change factors varied with time and space. The feedback of freshwater DOC to global change was also substantially different across time and space. But there is little information regarding the feedback of freshwater DOC to global change, and much less is known about the feedback mechanism of freshwater DOC to global change. Based on present researches, more attention should be devoted to the three aspects: (1) to expand research areas to understand the temporal dynamic characteristics of DOC in freshwater ecosystems in different regions; (2) to better understand the effect of global change on DOC composition and structure in freshwater ecosystems; and (3) to gain better insight into the feedback degree and mechanism of freshwater DOC to global change.

Application and progress of Cd isotope technology in environmental science.

WEI Rong-fei1,2, GUO Qing-jun1**, YANG Jun-xing1, ZHU Guang-xu1,2, ZHANG Han-zhi1,2, Marc PETERS1, WANG Chun-yu1,2, WAN Ying-xin3

2014, 33(2):  525-536. 

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Recently, the environmental pollution by the heavy metal cadmium has become more and more serious. In order to improve environmental quality, it is very significant to identify and control the sources of Cd pollution. Cd isotopes have played an important role as powerful tracers in environmental science. Referring to the latest research of Cd isotopes, this paper discusses Cd isotopic principles, separation of Cd from samples, selection of the standard solutions, the method of determination and instrument mass fractionation correction, Cd isotopic composition and fractionation mechanism, and the application of Cd isotopes in environmental science. Considering the methods and procedures applied for previous studies, certain modifications with respect to the application of Cd isotopes in environmental science should be carried out. The Cd isotopic standard solutions should be unified. The methods of determining the composition of Cd isotopes and correcting instrument mass fractionation should be selected according to the Cd concentrations in different samples. More information on Cd isotopic compositions of natural substances is needed and the fractionation mechanism of Cd isotopes has to be further studied.

Elevational pattern of species richness and species range size of herpetofauna in Baishuijiang Nature Reserve: A test of  Rapoport’s rule.

ZHENG Zhi, GONG Da-jie**, SUN Cheng-xiang

2014, 33(2):  537-546. 

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Elevational patterns of species richness and species range size and their underlying mechanisms have long been one of controversial issues in biogeography and biodiversity. Elevational Rapoport’s rule believes that the species richness gradually declines with increasing elevation, while the species ranges become larger. In this paper, we analyzed the elevational patterns of herpetofaunal (including amphibians and reptiles) species richness and species range in Baishuijiang Reserve by use of the herpetofaunal elevationdistribution dataset. Meanwhile, we examined the relationships between species richness and their distributional middle point in elevational content for different groups, faunas and taxonomic units and tested the Rapoport’s rule by using general four methods, which were Stevens’ method, Pagel’s method, mid-point method and cross-species method, respectively. The results suggested that herpetofaunal species richness declined monotonically with increasing elevation in Baishuijiang Reserve, which conformed the elevational Rapoport’s rule. Water availability might be the most important environmental factor determining amphibian species richness whereas temperature tends to be more important to reptile species richness, which is consistent with different physiological requirements of the two groups of organisms. The highest proportions of herpetofauna, especially small-range species were found at the lower elevational bin. Therefore, more attention to protect herpetofaunal species should be paid in the lower elevational bin. The consequences to test Rapoport’s rule by Stevens’ method, Pagel’s method and cross-species method conformed the Rapoport’s rule. However, the results by midpoint method rejected the Rapoport’s rule and suggested a unimodal model because of mid-domain effect. Hence, mythology has a massive effect on testing Rapoport’s rule. Tests of Rapoport’s rule are limited by methodological considerations, and various comparisons among empirical tests are needed in order to generate conclusive insight into elevational patterns of species range size, and the mechanism shaping such patterns.

Measuring and modeling leaf area index for Artemisia ordosica.

TANG Si-ling1, JIA Xin1**, GUO Jian-bin1, CHEN Zhi-hao1, ZHA Tian-shan1, QIN Shu-gao1, YANG Lin2

2014, 33(2):  547-554. 

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Leaf area index (LAI) of a semiarid Artemisia ordosica community at Yanchi, Ningxia was measured with both direct (allometric equations) and indirect (Li-2000 canopy analyzer) methods throughout the growing season of 2012. Our objectives were to compare the direct and indirect measurements, to explore how actual leaf area index (LAI_a) values obtained from allometric equations can be used to calibrate effective leaf area index (LAI_e) measured by Li-2000, and to model seasonal LAI_a variations using climatic variables. Results showed that bivariate functions of height and canopy area generally predicted individual total leaf area better than did the functions of canopy area alone, and the fitting achieved highest coefficient of determination (R²) in July and August. Both LAI_e and LAI_a showed humpshaped seasonal patterns. A midseason stable period started from early July and ended in midSeptember. LAI_e was always greater than LAI_a over the growing season, with the mean values of LAI_e and LAI_a in the stable period being 1.15 and 0.31 m²·m^-2, respectively. LAI_e and LAI_a showed a twophase linear relationship over the growing season, separated by late August. LAI_e and LAI_a showed a weak relationship with rainfall or soil water content  in the growing season. LAI_a varied with accumulated temperature above 5 °C (∑D), first increasing with ∑D, and then being stable during the midseason. LAI_a showed a negative exponential relationship with the ratio of photosynthetically active radiation reflectance (ρ_p) to shortwave radiation reflectance (ρ_s) (ρ_p/ρ_s). Our results contribute to the understanding of LAI patterns in semiarid A. ordosica communities, could aid in the development of efficient and accurate methods for measuring LAI, and provide ground-based data for calibrating remotely-sensed information and for parameterizing processbased ecosystem carbon cycle models.