Table of Content

09 June 2012, Volume 31 Issue 06

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Articles

Responses of Arabidopsis thaliana's ammonium-hypersensitive mutants amosdand vtc1 to exogenous ammonium.

DONG Gang-qiang1,2, FENG Xiao-yu1,2, LI Guang-jie1,2, LI Bao-hai1, LI Qing1, SHI Wei-ming1**

2012, 31(06):  1327-1333. 

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This paper analyzed the differences in the responses of Arabidopsis thaliana’s two ammoniumhypersensitive mutants, amosd and vtc1, to exogenous ammonium at concentrations 0, 1, 5, 10, and 20 mmol·L^-1. The two mutants all showed ammonium-hypersensitive, but the sensitivity degree differed. With the increasing concentration of exogenous ammonium, the vtc1 showed ammonium toxicity earlier than amosd. However, when the exogenous ammonium concentration increased up to 20 mmol·L^-1, the amosd showed heavier toxicity symptom than vtc1, suggesting the vital roles of AMOSD in plant tolerance to high ammonium stress. When the two mutants suffered from the stress of exogenous ammonium, the plant tissues where the highest toxicity degree occurred had somewhat difference. As the amosd suffered from the stress, the development of true leaves was arrested most; when the vtc1suffered from the stress, root elongation was repressed most. Partial ammonium supply experiment showed that the amosd had ammonium- hypersensitivity when the shoots were supplied with ammonium, while the vtc1 did not have the same phenotype unless the roots were supplied with ammonium. These results clearly indicated that vtc1 was a root-supply ammonium hypersensitive mutant, while amosd was a leaf-supply ammonium hypersensitive one. With the development of foliar spraying and the increasing deposition of ammonium from atmosphere, plants are facing higher and higher ammonium stress, and thus, it is of importance to increase the plant shoot tolerance to ammonium stress. This study indicated that, due to its unique characteristics of hypersensitive to shoot-supply ammonium, mutant -amosd could be a suitable genetic material to study the mechanisms of plant shoot tolerance to ammonium stress, and useful to more systemically understand the mechanisms of plant ammonium toxicity and improve plant ammonium tolerance.

Physiological differences of Trifolium repens and Trifolium pratense in response to freezingthawing stress.

ZHOU Rui-lian**, ZHAO Mei, ZHANG Ping, WANG Yan-jie, ZHAO Yan-hong

2012, 31(06):  1334-1340. 

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A pot experiment with white clover (Trifolium repens) and red clover (T. pratense) was conducted to study their growth and physiological indices under the stress of freezing-thawing cycle, aimed to understand the effects of future climate change on the growth of clover. After the stress, white clover survived, while red clover dead. The leaf membrane permeability, MDA content, antioxidant enzymes activity, and osmoregulation substances contents of the two clovers increased in thawing-freezing phase but decreased in freezing-thaw phase. During thawing-freezing and freezing-thawing, the leaf POD and CAT activities of cold-resistant white clover were higher than those of coldsensitive red clover, the white cover’s leaf proline content was 5 times higher than red clover’s, and the leaf membrane permeability of white clover was lower than that of red clover. All the physiological indices of white clover peaked at -5 ℃ while those of red clover peaked at -10 ℃, suggesting that -5 ℃ would be a temperature point at which the physiological regulation reaction occurred to make white clover’s leaf cell adapt to ice formation and ice melting, and maintain the balance between oxygen free radicals production and scavenging. Our results suggested that white clover had higher capability to adapt to freezing-thawing cycle, and could be a good landscaping species in future application and popularization.

Characteristics of cadmium tolerance and enrichment of Hemerocallis fulva.

ZHANG Cheng-xiang1, CHEN Wei-feng1**, LI Wei2

2012, 31(06):  1341-1346. 

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A pot experiment was conducted to study the cadmium (Cd) tolerance and enrichment of Hemerocallis fulva at different levels of Cd addition. The growth of H. fulva was stimulated when growing at Cd level 0.5 mg·kg^-1, but inhibited when the Cd level was higher than 5 mg·kg^-1. The greening and flowering periods of H. fulva- were prolonged at Cd level less than 5 mg·kg^-1. With the increasing concentration of Cd in the medium, the root activity and leaf chlorophyll and water contents decreased, leaf free proline and soluble sugar contents decreased after an initial increase, and leaf membrane permeability increased gradually. The absorbed Cd in H. fulva was more distributed in root than in shoot. With the increasing concentration of medium Cd, the Cd concentration in shoot and root increased, but the enrichment coefficient and translocation coefficient decreased. The maximum accumulation of Cd in H. fulva was 1.489 mg·plant^-1 when growing at Cd level 20 mg·kg^-1. Based on the growth characteristics and Cd-enrichment capability, H. fulva could be a potential plant used for the remediation of Cd-polluted soil when the soil Cd concentration was less than 1 mg·kg^-1.

Effects of NaCl stress on the growth and chlorophyll fluorescence characteristics of poplar seedlings.

WU Chuan-lan, LONG Xiao-hua, JIN Shan-zhao, LIU Lin, WANG Chang-hai, LIU Zhao-pu**

2012, 31(06):  1347-1352. 

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In order to understand the salt-tolerance of poplar, the seedlings of poplar cultivars Nanyang No. 1 and Nanyang
No. 2 bred by the Jiangsu Provincial Key Laboratory of Marine Biology were taken as the test materials to study their dry weight, water potential, chlorophyll content, chlorophyll fluorescence parameters, and light energy absorption and distribution under the stress of different concentrations NaCl. At low concentration (75 mmol·L^-1) NaCl, the plant dry weight, chlorophyll content, q_P, Yield, and ETR of Nanyang No. 1 were significantly lower than those of Nanyang No. 2. The decrement of the water potential of Nanyang No. 1 was higher than that of Nanyang No. 2, while the F_m/F_v and F_m′/F_v′ of the two cultivars had less change. At high concentration (150 mmol·L^-1) NaCl, there were no significant differences in the inhibitory effects of salt stress on Nanyang No. 1 and Nanyang No. 2. Under salt stress, Nanyang No. 2 had higher average value of P_c but lower proportion of H_d than Nanyang No. 1, while the average value of E_x of the two cultivars had little difference. Above all, due to the higher activity of photosystem Ⅱ, Nanyang No.2 had higher salt-tolerance than Nanyang No. 1.

Characteristics of Populus euphratica leaf water and chlorophyll contents in an arid area of Xinjiang, Northwest China.

NIU Ting1,2, Alishir Kurban1,2**, Umut Halik3, Philipp Gartner4, Birgit Kleinschmit4, Abdimijit Ablekim1, Suriyegul Hemidul5, LIU Gui-lin1,2

2012, 31(06):  1353-1360. 

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In August 2011, forty Populus euphratica plants at the Arghan monitoring section in the lower reaches of Tarim River were selected to study the spatial differentia of their leaf physiological traits and surface temperature. The plants had different distances from the River. A significant (P<0.01) negative correlations were observed between the leaf fuel moisture content (FMC), equivalent water thickness (EWT), and chlorophyll content and the distance of the plants from the River. All the former three variables decreased significantly with the distance from the River. Leaf surface temperature had significant effects on the leaf FMC and EWT (P<0.01), but minor effects on the chlorophyll content (P>0.05). Due to the differences in the physical interpretation of FMC and EWT, their mean values were significantly correlated at tree level (P<0.01), but less correlated at single leaf level. However, the correlation between EWT and chlorophyll content were significant (P<0.01) both at tree level and at single leaf level. Because of the significant correlation with chlorophyll content and with the distances of trees from river, leaf EWT could be used as a vegetation water index for remote sensing-based monitoring in arid area riparian ecosystems.

Effects of Spartina alterniflora invasion on methane emission from coastal brackish marsh.

XIANG Jian1,2, LIU De-yan1, YUAN Jun-ji1,2, DING Wei-xin1**

2012, 31(06):  1361-1366. 

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Natural wetland is one of the key sources for atmospheric methane. Spartina alterniflora invasion generally increases the soil organic carbon content in coastal marshes of China. In this study, three intact soil cores were collected from the coastal brackish marshes having been invaded by S. alterniflora for 8, 11 and 15 years, respectively, and a pot experiment was conducted to investigate the effects of soil organic carbon content on the methane emission from coastal brackish marsh. The soil organic carbon content increased with the increasing year of S. alterniflora invasion, and the methane emission had an apparent seasonal pattern, with the peak in September. During growth season, the mean methane flux of the marsh having been invaded by S. alterniflora for 15 years and with the soil organic carbon content of 12.97 g·kg^-1 amounted to 2.94 mg·m^-2·h^-1, which was significantly higher than that (1.95 and 2.34 mg·m^-2·h^-1) of the marshes after 8 and 11 years S. alterniflora invasion and with the soil organic carbon content of 8.11 and 9.16 g·kg^-1, respectively. It was considered that the increased soil organic carbon content not only increased the supply of dissolved organic carbon for methanogens, but also- stimulated the growth of methanogens, which together elevated the methane emission from the coastal marshes invaded by S. alterniflora.

Effects of soil under Alternanthera philoxeroides-invaded plant community on the growth of plants.

LI Yong-hui1,2, LI Jun-min2, YAN Ming1**

2012, 31(06):  1367-1372. 

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The soils under native plant community with and without Alternanthera philoxerodies invasion were taken as the growth medium to study whether plantsoil feedback contributes to the invasion success of A. philoxeroides. The soil under A. philoxeroidesinvaded community inhibited the growth of native A. sessilis significantly, which manifested in the decreases of root biomass, stem biomass, total biomass, relative growth rate, and net assimilation rate, and in the changes of morphological traits, e.g., the decreases of stem length, branch number, root length, and root volume. The biomass partitioning of native A. sessilis also changed, with a significantdecrease of leaf/mass ratio and increased root/mass ratio and root/shoot ratio. However, the soil under A. philoxeroidesinvaded community did not significantly affect the growth of invasive A. philoxeroides, according to the data of biomass and morphological traits. The soil under A. philoxeroidesinvaded community only significantly increased the leaf number and leaf/mass ratio of invasive A. philoxeroides. The significant negative and neutral effects of soil under A. philoxeroidesinvaded community on the native A. sessilis and invasive A. philoxeroides, respectively might contribute to a positive feedback loop, leading to the increased dominance of invasive A. philoxeroides in the invaded community. The results indicated that soil might play important role in the successful establishment and maintenance of A. philoxeroidespopulation in its invaded area.

Effects of soil water stress on Linum usitatissimum emergence.

WANG Ping1, ZHANG Li-feng1,2**, LI Ming1

2012, 31(06):  1373-1377. 

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By the method of establishing artificial moisture gradient and based on completely controlling environment, an experiment was designed to study the relationships between soil water stress and flax (Linum usitatissimum) seedling emergence as well as the soil moisture critical value for the emergence resisting soil drought, aimed to ensure the springsowing crop seedlings safely in northern arid or semiarid regions of China. The responses of the emergence to soil moisture exhibited 3 types, i.e., jump, ascending, and S-curve. The moisturesensitive domain of the emergence was from 3.5% to 6.0% for sandy chestnut soil, and from 9.0% to 15.0% for meadow chestnut soil. Taking the emergence rate as a standard, the soil moisture threshold value was 5.5% for sandy chestnut soil, and 13.0% for meadow chestnut soil. With the drought-resistance and conserving seedling as the standard, the soil moisture threshold value was 5.0% for sandy chestnut soil, and the seeding level should be increased to 1.52 times of that in average years. When the soil moisture threshold value for meadow chestnut soil was 12.0%, the seeding level should be increased to 1.72 times of that in average years.

Effects of water temperature on cucumber plug breeding in summer.

LI Sheng-li**, LIU Jin, SUN Zhi-qiang

2012, 31(06):  1378-1382. 

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In order to decrease the node position of the first female flower in cucumber plug breeding in summer, an experiment with cucumber cultivar ‘Yousheng F1’ was conducted to study the effects of watering with different temperature water (7 ℃, 11 ℃, 15 ℃, 22 ℃+ ethylene) on the position of the first female flower and its growth and development, taking the water with temperature 22 ℃ as the control. As compared with the control, all the treatments except 22 ℃ water + ethylene resulted in the decrease of the position of the first female flower and the enhancement of seedling index. At the growth stage of fourleaf and one tip, the seedling height in treatment 7 ℃ water reduced by 24%, stem diameter increased by 10%, and the first female flower position was at 4.8, whereas the seedling dry mass in treatment 11 ℃ water increased by 14%, and the first female flower position was at 5.6. Though the two treatments were all significantly better than the control and treatment 22 ℃ water + ethylene, treatment 11 ℃ water could be more suitable for cucumber plug breeding, in considering the economic input.

Phosphorus cycling in rice-duck mutual ecosystem in double cropping rice growth seasons.

ZHANG Fan1,2**, CHEN Yuan-quan2, GAO Wang-sheng2

2012, 31(06):  1383-1389. 

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Rice-duck mutualism is the development of raising duck in rice field in Chinese traditional agriculture. In this study, a field experiment of raising duck in rice field was conducted in a double cropping rice region of Hunan Province from May to October 2010, and an input-output analysis was made to analyze the phosphorous (P) cycling in the riceduck mutual ecosystem, taking a conventional rice field as the control. Neither pesticides nor herbicides were applied throughout the growth period of rice in the riceduck mutual ecosystem. In the early rice-duck mutual ecosystem, the P output was 52.28 kg·hm^-2, of which, the P output from duck was 1.71 kg·hm^-2; in the late rice-duck mutual ecosystem, the P output was 83.24 kg·hm^-2, of which, the P output from duck was 6.17 kg·hm^-2. During the double cropping rice growth seasons, the P inputs of the rice-duck mutual ecosystem decreased the P deficit in soil subsystem. The P input of duck subsystem mainly came from feed P, and the cycling rate of duck feces P in the mutual ecosystem in early rice and late rice growth seasons was 12.5% and 13.5%, respectively. After late rice harvesting, the P sequestration in soil was 195.41 kg·hm^-2. In contrast with conventional rice, riceduck mutualism decreased the deficit of soil P, while increased the soil P sequestration by 36.9%. This study provided reference for further development and utilization of rice-duck mutualism in this country.

Damaged status and early recovery of tree species in Wuzhishan of Nanling Mountains, South China after the ice storm in 2008.

HUANG Chuan-teng, ZHUANG Xue-ying**, LI Rong-xi, LIU Zhao-xiang, JIANG Bin, ZHAI Cui-hua

2012, 31(06):  1390-1396. 

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By using belt transect method, an investigation was conducted on the damaged status and early recovery of the dominant tree species and protected tree species in Wuzhishan of Nanling Mountains after the ice storm in 2008. On three belt transects of 2-7 km long and 15 m wide, a total of 2832 trees with diameter at breast height (DBH) >2 cm were recorded, belonging to 141 species of 53 families and 96 genera. The damaged rate was 73%, of which, 61% was slightly damaged. About 84% of the damaged individuals more or less recovered one year after the ice storm, but nearly 16% did not recover, died, or were dying. For the dominant tree species in Fagaceae, Lauraceae, Magnoliaceae and Hamamelidaceae, their damaged rates and recovery rates were higher. Fifteen nationally protected tree species were recorded, of which, Pinus kwangtungensis and Fokienia hodginsiiwere most common. Except for Cephalotaxus fortunei and Amentoxtaxus argotaenia, the other protected species were more or less damaged, with 59% of them died or dying. In addition, 25% of the low density species with <3 individuals suffered various damages or died. The extreme ice storm in 2008 caused serious damage to the forest trees, but most species could recover naturally by sprouting. However, the loss of some rare and vulnerable species could alter the species composition, and further, affect the community succession process in the future.  

Decomposition dynamics of Pinus tabulaeformis leaf litter at urban and suburban sites of Shenyang, Northeast China.

GUO Fang-qin1,2, HE Xing-yuan1, CHEN Wei1**, HUANG Yan-qing1

2012, 31(06):  1397-1403. 

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To examine the effects of site location and litter type on litter decomposition, a reciprocal decomposition experiment was conducted to study the effects of contrasting sites (urban vs. suburban) and leaf litter types (urban leaf litter vs. suburban leaf litter) on the mass loss rate and N- and P remaining percentages of Pinus tabulaeformis leaf litters when decomposing in urban stand and suburban stand, respectively. The one year experiment showed that different sites had significant effects on the decomposition rate of P. tabulaeformis leaf litters (P<0.05). The leaf litters decomposed faster at suburban site than at urban site, suggesting that environmental conditions had significant effects on the decomposition. In the same stands, different litter types had significant effects on the litter decomposition (P<0.05). The decomposition rate of the litters was faster at urban site than at suburban site, suggesting the significant effects of inherent characters of the litters. Site had no significant effects on the N-and P remaining percentages, but litter type had significant effects. Urban leaf litter, due to its higher initial C/N and C/P, were easy to enrich N and P during decomposition, as compared with suburban leaf litter.

Spatial distribution of the biomass of Vaccinium uliginosum community under Larix olgensisforests in Changbai Mountains, Northeast China.

LI Gen-zhu, WANG He-xin**, CHEN Ying-min, ZHANG Zi-chuan, WU Feng-zhang, HAN Hui

2012, 31(06):  1404-1410. 

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An investigation was conducted on the below- and aboveground  biomass and its spatial distribution of Vaccinium uliginosum community  under Larix olgensisforests in Changbai Mountains. The above-ground biomass of the V. uliginosum community was mainly distributed below the height of 50 cm, and the biomass of the branches with a diameter of 3-5 mm occupied the largest portion. The belowground  biomass accounted for 75.2%-92.6% of the total, and was mainly (66.3%-85.0%) distributed in dead moss layer where the biomass of fine roots (<1 mm) accounted for 42.6%-82.7% of the total. In peat layer, the root biomass accounted for 12.3%-29.7% of the total. The root biomass of V. uliginosum accounted for 8.8%-60.7% of the total root biomass of all plant species, and the fine root biomass of V. uliginosum occupied a great portion. This study provided basis for the rational protection and utilization of V. uliginosum resources and the evaluation of the carbon sequestration of the ecosystem.

Effects of forestry ecological engineering on herb community in coastal saline-alkali land.

SHAN Qi-hua1, ZHANG Jian-feng1**, SHEN Li-ming2, TANG Hua-jun3, RUAN Wei-jian3, CHEN Guang-cai1

2012, 31(06):  1411-1418. 

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Forestry ecological engineering, an important measure for the ecological amelioration of our coastal salinealkaline land, has definite effects on the local natural ecosystem. This paper studied the effects of forestry ecological engineering on the herb community in a salinealkali land at the Yuyao section of Hangzhou Bay. On the land, a shelterbelt of 3.5 km in length and 30 m in width and between two originally existed lands, namely, farmland and wasteland, was constructed with comprehensive ecological engineering measures. The herb community structure and diversity in the farmland, forestland, and wasteland were investigated by visual and sampling plot methods, with the species, species-area relationship, frequency, biomass, summed dominance ratio (SDR), richness, Pielou evenness index, Shannon index, and Simpson index as the indicators. In the whole study area, a total of 31 herbaceous plant species belonging to 30 genera and 14 families were recorded. Poaceae and Asteraceae dominated everywhere. Compared to the farmland and wasteland, the herb community in the shelterbelt exhibited obviously different ecological traits, including varied species, enlarged minimum area, more complex structure, and increasing species diversity. The habitat filter functioned efficiently in the ameliorated zone, while the competitive exclusion did not temporarily. It was concluded that forestry ecological engineering disturbed the primary structure and diversity of the plant species in the coastal saline-alkali land, leading to a new plant succession in the restoration zone, and implying a great ecological efficiency.

Life table and survival analysis of natural Davidia involucrata  population in Fanjing Mountain Nature Reserve, Guizhou Province of Southwest China.

WU Ming-kai1，2, SHEN Zhi-jun2,3, LIU Hai2,3, WU Yan-you1**, HE Nu-tai4, QIU Yang4, YANG Ni4, YANG Ning4

2012, 31(06):  1419-1424. 

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Based on the population life table and the theory of survival analysis, and by using the age class structure represented by DBH (diameter at breast height) class and the stage-smoothing technique, a specific life table of Davidia involucrata population in Fanjing Mountain Nature Reserve was compiled, and the mortality rate curve, killing power curve, survival rate curve, and survival function curve were analyzed, aimed to reveal the quantitative dynamics of the population. There was a fluctuation in the structure of the D. involucratapopulation. The survival curve of the population appeared to be of Deevey Ⅲ type, and the individuals at young stage were abundant. The mortality rate curve and disappearance rate curve in the lifespan had similar variation trend, and the population had two distinct peaks of mortality, i.e., from Ⅰ to Ⅱ age class and from Ⅷ to Ⅸ age class. The survival analysis showed that the population mortality rate was increasing all along, while the survival rate was decreasing all the time. After Ⅷ age class, the mortality rate would exceed 92%, and the survival rate would decrease to below 8%, which indicated that hazard rate surpassed survival rate. The survival functional curve showed that the individual number of the population decreased rapidly in early age period, was stable in middle age period, and declined in old age period. The high mortality of seedlings and the deficiency of middle-age trees could be the main reasons leading to the D. involucrata population becoming endangered.

Effects of lakeside plant spatial allocation in plateau wetlands of Yunnan, Southwest China on the removal of sewage nitrogen and phosphorus.

LI Yin1, TIAN Kun1,2**, XIAO De-rong2, YANG Qian1, XIE Wen-ying1

2012, 31(06):  1425-1431. 

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Field investigation in combining with laboratory simulation test was conducted to study the effects of 7 lakeside plant communities commonly found in plateau wetlands on the purification of different concentration urban sewage, aimed to provide reference to the selection and spatial allocation of plants for the recovery of degraded wetlands and the treatment of polluted lakes in Yunna Plateau of Southwest China. The test lakeside plant communities had definite limitations in enduring and purifying urban sewage. Only under the conditions of suitable sewage concentration (total nitrogen 8.39-22.95 mg·L^-1, total phosphorous 0.61-1.96 mg·L^-1, and NH₄⁺-N 6.42-19.80 mg·L^-1), the plant communities could have effective and obvious purification effects, with the removal rate of total phosphorous and NH₄⁺-N reached over 30% and that of total nitrogen nearly 20%. Under high sewage concentration, the plant communities composed of the species in favor of nitrogen and phosphorus, such as Zizana caduciflora, Potamogeton pectinatus and Ceratophyllum demersum, showed better purification effects. There existed significant differences in the purification effects among the plant communities composed of one same species but different other species (P<0.05), indicating the interactions among the plant species. It was suggested that plant species selection and their spatial allocation would have great significance in the biotreatment of polluted lakes and the ecological recovery of degraded wetlands.

Nutrient status of Qidong nearshore water area and its relations to  water environmental quality of adjacent rural areas.

LI Hong-li1,2**, WANG Jian-hong1,2, GAO Xin-xin3, WANG Chang-you1,2

2012, 31(06):  1432-1437. 

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Based on the 2003-2009 monitoring data from seven stations in the nearshore water area of Qidong, this paper analyzed the eutrophication status of this water area and its relations to the water environmental quality of adjacent rural areas. At the stations except Pingta, there was an increasing trend in the water COD, DIN, DIP, and DO. The waters at all the stations, except at Pingtai in 2003, were in eutrophication. The nutrient status index reached the highest value in 2007, and kept dropping down after then. In the study period, the seriously polluted water area occupied 4.1% of the total, and the water quality was the worst in 2007 and 2008. The eutrophication index had a significant positive correlation with the comprehensive standard index. Relative to the discharge of urban industrial waste water and domestic sewage, the water environmental quality of adjacent rural areas as well as the runoff of Changjiang River had minor influence on the nutrient status of Qidong nearshore water area.

Influence of cage culture on methylmercury in water column of reservoir.

FENG Cai-yan1,2, YAN Hai-yu1**, YU Ben1,2, LI Qiu-hua3

2012, 31(06):  1438-1446. 

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To understand the influence of cage culture on the methylmercury production and distribution in water column of reservoir, water samples were collected from four cage culture sites in Wujiangdu Reservoir in September (warm season), 2010 and in March (cool season), 2011, taking the sites with a distance of 100-200 m from the culture sites and at the center of the reservoir as the reference sites. In warm season, the total mercury (THg) and methylmercury (MeHg) concentrations in cage culture sites were 2.04±0.53 ng·L^-1 and 0.146±0.231 ng·L^-1, and those in reference sites were 3.33±2.39 ng·L^-1 and 0.380±0.577 ng·L^-1, respectively; in cool season, the corresponding values were 3.04±1.53 ng·L^-1 and 0.047±0.028 ng·L^-1, and 3.24±1.23 ng·L^-1 and 0.046±0.013 ng·L^-1, respectively. No significant differences were observed in the concentrations of THg and MeHg (for THg, n=35, P=0875, andforMeHg,n=35,P=0.091) between cage culture sites and corresponding reference sites. The analysis on the water parameters total phosphorus, total nitrogen, dissolved organic carbon, temperature, and chlorophyll-a at the cage culture sites and reference sites showed that the MeHg production and distribution in the water column were affected by the water discharge and water exchange activities in the reservoir rather than by the cage culture activities, whereas the anaerobic condition of bottom water and the variation of water temperature caused by the seasonal stratification of water column could be the main factors affecting the methylmercury production and distribution.

Screening and identification of denitrifying bacillus strain and its denitrification characteristics.

ZHENG Xi-chun1, GUO Xiao-jun1, YAO Na2, CAO Xiao-lu2, LI Lu-bin2, ZHU Bao-cheng1**

2012, 31(06):  1447-1452. 

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By the methods of heating accumulation, nitrate-reduction gas production, and quantitative analysis of denitrification, a bacillus strain with highefficient denitrifying capability named as TGR30 was isolated from the sediment of Wuliangsuhai Lake. The isolate was identified as Bacillus megaterium, based on its morphological feature, biochemical characteristics, and 16S rDNA sequence analysis. Single factor experiment was conducted to investigate the influences of medium carbon, C/N, salinity, pH, and dissolved oxygen on the denitrifying characteristics of the strain. When the medium salinity was 6% or the pH value was 12, the strain still had high nitrogen removal capability, and the optimal conditions for the nitrogen removal were the medium C/N ratio 14, pH value 8.0, and dissolved oxygen concentration 4 mg·L^-1 when soluble starch was used as the sole carbon source.

Identification of bio-control bacterial strain KJB04-11 against soybean root rot disease and the produced lipopeptide antibiotics by the strain.

LI Xu, MA Fu-hai, WANG Xiu-juan, SUN Jian, ZHANG Hui-wen**

2012, 31(06):  1453-1460. 

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A bacterial strain KJB04-11 with antagonistic effect against Fusarium oxysporum and Rhizoctonia solani was isolated from soybean rhizosphere. The strain was identified as Bacillus subtilis, based on its morphological, cultural, physiological, and biochemical characteristics, and 16S rDNA sequence analysis. The fermented filtrate with antagonistic activity showed certain thermostability and certain acidic and alkaline stability in the range of pH 1.0-13.0. The antagonistic active compositions in the fermented filtrate were purified by gel filtration on Sephadex G₂₅ column and RF-HPLC, and preliminarily identified as C16 mycosubtilin, C₁₇ mycosubtilin, and C₁₅ surfactin by infrared spectra, MALDI-TOF mass spectrum, amino acid composition analysis, and amplification of lipopeptide synthase gene. In field trial, the control efficacy of seed coating agent prepared with KJB04-11 against soybean root rot disease was 53.6%, and the soybean yield was increased by 12.5%

Screening, identification, and activity assessment of endophytic actinomycetes from tomatoplants against Botrytis cinerea.

XU Da-yong, LI Feng**

2012, 31(06):  1461-1467. 

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In this study, the endophytic actinomycetes in tomato plants in the farmlands in Huaibei City of Anhui Province were isolated and screened, and the bioactivities of the actinomycetes against pathogenic fungus Botrytis cinerea were determined. The population density of the actinomycete in the tomato roots, stems, and leaves were 5.66×10⁴, 0.67×10⁴, and 0.39×10⁴ CFU·g^-1 fresh weight, respectively. According to the isolation position and phenotype characteristics, a total of 93 endophytic actinomycete strains were isolated from different tissues of healthy tomato plants, and, by using dual culture technique, 7 strains with antagonistic activities against B. cinerea were screened, accounting for about 7.5% of the endophytic actinomycetes isolated. Among the 7 strains, the HNU-EA27 isolated from tomato roots had the best inhibition effect, with a formed inhibition zone of 28.3 mm. Based on the morphology, cultural characteristics, physiological and biochemical properties, chemotaxonomy, and 16S rDNA sequencing, the HNU-EA27 was identified as Streptomyces toxytricini.The culture filtrate of HNU-EA27 could inhibit the mycelium growth and spore germination of B. cinerea. The higher concentration the culture filtrate, the stronger the inhibition activity was. 30% culture filtrate of the HNU-EA27 could completely inhibit the mycelium growth and spore germination of B. cinerea. Pot experiment showed that the prevention efficiency and cure efficiency of 30% HNU-EA27 culture filtrate against tomato gray mould were 80.6% and 73.8%, respectively, being superior to those of the 600-fold dilution of 50% badistan. It was suggested that the strain HNU-EA27 could be valuable in the bio-control of tomato gray mould.

Effects of organic and chemical fertilizer applications on the diversity of soybean rhizobia.

LIU Pu-fang, WANG Hong-yan**

2012, 31(06):  1468-1472. 

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The rhizobial DNA was extracted from the root nodules of soybean plants at a 6-year experiment site on black soil, and PCR-DGGE and clone sequencing were adopted to analyze the effects of different fertilization treatments on the diversity of soybean rhizobia. In the treatment no fertilization, the band number of nifH gene and the diversity indices were the highest, and there existed significant differences in the diversity indices among different treatments, with the order of no fertilization > high application rate of organic manure > low application rate of organic manure, 1/2 organic manure plus 1/2 chemical fertilizer > high application rate of chemical fertilizer > low application rate of chemical fertilizer. Cluster analysis demonstrated that the fingerprints in treatments of chemical fertilization only had a similarity of 66% with those in other treatments, suggesting that chemical fertilization could significantly alter the community structure of soybean rhizobia. The PCR-DGGE and clone sequencing showed that most of the rhizobia were belonged to Bradyrhizobium. The application of organic manure and chemical fertilizer, especially the latter, could decrease the diversity of soybean rhizobia.

Toxic effect of nonylphenol onPaphia undulata visceral mass.

GONG Xiu-yu1,2, CHEN Hai-gang1, ZHANG Zhe1, MA Sheng-wei1, HUANG Zhi-fei1,3, WANG He-wei1,3, WANG Tao4, CAI Wen-gui1**

2012, 31(06):  1473-1479. 

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A semi-static toxicity test was conducted to determine the 96h median lethal concentration (96h LC₅₀ value) of nonylphenol (NP) to Paphia undulata. In the meantime, the variations of superoxide dismutase (SOD), glutathione (GSH), and peroxidase (POD) activities and malondialdehyde (MDA) content in the visceral mass of P. undulata were studied when exposed to different concentrations NP (low: 1 μg·L^-1; medium: 10 μg·L^-1; and high: 25 μg·L^-1) and during the recovery stage in clear sea water. The 96h LC₅₀ value was 260 μg·L^-1. At the early stage of stress, the SOD activity in the visceral mass of P. undulata exposed to low and medium NP concentration was inhibited (P<0.01) while the POD activity was induced (P<0.01), showing the typical “excitotoxicity effect”. During the stress period, the SOD activity and GSH content in the visceral mass at low and medium NP concentrations  increased after an initial decrease, while the POD activity and MDA content were in adverse. When exposed to high NP concentration, the SOD activity was inhibited first and induced then, the POD activity and MDA content increased after an initial decrease, while the GSH content was significantly higher than that of the control level in whole exposure time. The GSH and MDA contents in whole exposure time appeared sharp fluctuation, and the variation increased with increasing NP concentration. During recovery period, all the test indices in the visceral mass of P. undulata exposed to low and medium NP concentration recovered gradually to the normal level, but, for the P. undulata exposed to high NP concentration, these indices remained significant difference, as compared to the control group. The above results indicated that NP had obvious impact on the antioxidant system in the visceral mass of P. undulata, while P. undulata had self-repairing ability for the oxidative damage caused by certain degree of NP stress, but, at high NP concentration, the lipid peroxidation damage could not recover to the level of the control group in a short time.

Impacts of long-wave ultraviolet radiation on kidney structure of Bufo Raddei.

QU Ting-ting, LI Pi-peng, NIE Ying, LU Yu-yan**

2012, 31(06):  1480-1486. 

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In order to study the damage of long-wave ultraviolet (UVA) on Bufo raddei kidney, three groups of Bufo raddeisjuveniles were irradiated continuously by 365 nm UVA with a dosage of 352 μW·cm^-2 for 150, 300, and 450 min, respectively, and the kidney after the irradiation was dissected immediately and 3, 6, 9, 12, and 15 days later, with its histological changes observed by general histological method. After the UVA radiation, the kidney structure was basically in integrity, except the fracture and visible constriction of renal tubule and the disappearance of renal capsule, which were most obvious in the 300 min group, followed by in 450 min group and in 150 min group. The damage to Malpigkian bodies was more serious in 300 and 450 min groups than in 150 min group. After 15 days recovery, though the damage was somewhat mitigated, most of the histological indices of the three experimental groups were significantly different from the control group. This study showed that the damage of UVA to B. raddei kidney could not be ignored in spite of the kidney’s self-repair capability. In the field, the enhancement of UV radiation and the reduction of vegetation could cause amphibians suffering excessive UV radiation, and even, amphibian population decline.

Factors affecting body-turning behaviors of Bradybaena ravida ravida.

ZHANG Min-zhao, CAI Xue, ZONG Yu, QIN Xiao-chun, WANG Jin-zhong, SUN Shu-ling, ZHANG Zhi-yong**

2012, 31(06):  1487-1491. 

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In this study, the body-turning behaviors of Bradybaena ravida ravida were studied by recording the duration of the snails resuming their original posture after being put upside down. The effects of the factors such as snail body weight, environmental temperature, illumination intensity, and the time of feeding and starvation on the body-turning duration were also studied. The bodyturning duration increased with the increase of snail body weight, illumination intensity, and starvation time, but decreased with the increase of environmental temperature and feeding time. The durations of the bodyturning of groups Ⅳ and Ⅴ (snail body weight was 0.7-0.9 g and 0.9-1.2 g, respectively) were significantly longer than those of groups Ⅰ, Ⅱ, and Ⅲ (snail body weight was 0.1-0.3 g, 0.3-0.5 g and 0.5-0.7 g, respectively) (P<0.01), and the duration of body-turning of groupⅠ was significantly shorter than that of group Ⅲ (P<0.05). At higher temperature and weaker illumination intensity from electric incandescent lamp (204 lx), the body-turning durations of groups Ⅰ, Ⅲ, and Ⅴwere significantly shorter than those at lower temperature and stronger illumination intensity (493 lx). The body-turning durations of groups Ⅰ and Ⅴ that starved for longer time were significantly longer than those starved for shorter time. When fed for longer time, the body-turning durations of groups Ⅲ and Ⅴ were significantly shorter than those fed for shorter time.

Burrow utilization by great gerbil Rhombomys opimus and its behavior time budget on ground surface.

XIA Can-jun1,2, LIU Wei3, QIAO Hong-hai1,2, YANG Wei-kang1**, XU Feng1, David Blank1

2012, 31(06):  1492-1498. 

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From May to November 2011, and by the method of focal animal sampling, this paper studied the burrow utilization (activity intensity on ground surface and frequency of entering burrow) by great gerbil (Rhombomys opimus) and its daily time budget of outside burrows in the southern part of Gurbantunggut Desert. The great gerbil spent 77.62%, 66.13% and 80.93% of their daytime outside burrows in spring, summer and autumn, and the frequency of their entering burrow in the seasons were 0.50, 0.31 and 0.19 times·min^-1, respectively. Both the activity intensity on ground surface and the frequency of entering burrow differed significantly over seasons. Feeding was the main behavior on ground surface, and the proportion of the time budget for feeding was greater than 50% during the three seasons. Storing food was another important behavior in spring and autumn, with the proportion of the time budget being 1719% and 2546%, respectively. In summer, grooming became most common after feeding, occupying 27.78% of the time budget. Our results demonstrated that food was the most important factor forcing the great gerbil to stay on ground surface for long time. Air temperature, physiological cycle, and predation risk also affected the ground surface activity, frequency of entering burrow, and daily time budget of the great gerbil.

Effects of climate change on the occurrence of crop insect pests in China.

ZHANG Lei1, HUO Zhi-guo1**, WANG Li1, JIANG Yu-ying2

2012, 31(06):  1499-1507. 

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Based on the 527 meteorological stations observation data as well as the diseases and pests data and planted crop areas data in China agricultural areas in 1961-2010, and by the method of correlation analysis, this paper analyzed the effects of the changes of meteorological elements on the occurrence of insect pests. Under the background of climate change, the mean annual air temperature and mean precipitation intensity increased at a rate of 0.27 ℃·10 a^-1 and 0.24 mm·(d·10 a)^-1, respectively, while the annual sunshine hours decreased at a rate of 47.40 h·10 a^-1. The annual precipitation intensity increased at a rate of 0.14 mm·10 a^-1, but had great fluctuations. There were significant positive correlations between the rate anomaly of insect pests’ occurrence area and that of mean annual air temperature and precipitation intensity. When the mean annual air temperature increased by 1 ℃, the increasing rate of insect pests’ occurrence area would be 0.648, and the occurrence area would be increased by 0.96×10⁸ hm²·time; when the mean annual precipitation intensity increased by 1 mm·d^-1, the increasing rate of insect pests’ occurrence area would be 0.713, and the occurrence area would be increased by 1.06×10⁸ hm²·time. The rate anomaly of insect pests’ occurrence area had a significant negative correlation with that of annual sunshine hours. When the annual sunshine hours decreased by 100 h, the rate anomaly of insect pests’ occurrence area would be increased by 040, and the occurrence area would be increased by 0.59×10⁸hm² ·time. Overall, the rate anomaly of insect pests’ occurrence area had little correlation with that of annual precipitation, but significant negative correlations with the rate anomaly of mean annual small precipitation, days of microprecipitation, and days of small precipitation. When the mean annual small precipitation, days of microprecipitation, and days of small precipitation decreased by 1 mm, 1 d, and 1 d, the rate anomaly of insect pests’ occurrence area would be increased by 0.014, 0.066 and 0.052, and the occurrence area would be increased by 0.02×10⁸, 0.10×10⁸, and 0.08×10⁸ hm²·time, respectively.

Regional differentiation in the variations of  surface moisture index in north Tianshan Mountains in 1962-2009.

SUN Qin-ming1, LIU Tong1**, DONG He-gan1, ZHANG Rong1, LI Yong-guan1, QIN Chun-ming2

2012, 31(06):  1508-1516. 

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Surface moisture index is more objective than precipitation in describing regional drying-wetting feature and its changing trend under the background of global warming. Based on the meteorological data from 21 stations in 1962-2009, and by using detrended fluctuation analysis, spline interpolation, and least square fitting, this paper analyzed the spatiotemporal variations of  surface moisture index, precipitation, and air temperature in different sub-regions of north Tianshan Mountains, Xinjiang of Northwest China in 1962-2009. During the past 48 years, the temporal pattern of the moisture index showed a weak Hurst’s effect, i.e., the moisture index exhibited relatively weak persistence and relatively strong randomness through the time. There was a significant seasonal difference among the sub-regions. In desert oasis sub-region, the annual precipitation had an overall increase, but the moisture index varied spatially. The sub-regions that experienced significant drying also experienced significant warming, and the sub-regions with the most significant drying were the Ili Valley, followed by the west mountainous area and the eastern edge of Junggar basin. The ground surface drying-wetting also varied seasonally, with a trend of becoming drier in winter and autumn, followed by in spring, and wetter in summer.  

Responses of runoff in Hulun Lake basin of Inner Mongolia to climate change.

GU Run-yuan1, LI Si-hui2, ZHAO Hui-ying1,2**, LI Chong3, SONG Wei-shi4, MENG Jun4, WANG Yan-Ping4

2012, 31(06):  1517-1524. 

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By using Mann-Kendall nonparametric test, this paper analyzed the climate changes and their effects on the runoff in Hulun Lake basin in recent 50 years, based on the air temperature, precipitation, and evaporation data from 1961 to 2010 and the runoff data from 1961 to 2008. In the study area, the air temperature in 1961-2010 had an obvious increasing trend, the annual precipitation was greatly affected by summer precipitation and experienced four stages,i.e., increased in 1961-1964 and 1983-2003 and decreased in 1964-1983 and 2003-2010, and the annual evaporation retained a relatively stable state before 1973, had a decreasing trend in 1973-1998 and an increasing trend in 1999-2005, and then decreased, with an abrupt change point in 2005. The evaporation in summer and autumn corresponded well with the precipitation in summer. The runoff was plentiful in 1961-1965 and 1987-2002, but scarce in 1965-1987 and 2002-2008, with a significant decrease in 1975 to 1980. With the increase of air temperature, precipitation presented an overall decreasing trend, which determined the evaporation change to a great degree, and thus, the Hunlun Lake basin appeared a warming and drying tendency. On the basis of the runoff variation characteristics, a comparison was made on the change processes of the runoff, air temperature, precipitation, and evaporation. Correlation analysis indicated that the air temperature, precipitation, and evaporation in summer and autumn were the primary causes of the runoff variation in the Hunlun Lake basin.  

Effects of climate change on Poa crymophila phenology in alpine meadow grassland in northern region of Qinghai Lake, Northwest China.

ZHU Bao-wen1**, HOU Jun-ling2, YAN De-xing1, SONG Li-ming1, ZHENG You-fei3

2012, 31(06):  1525-1532. 

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Based on the field observation and meteorological data in the northern region of Qinghai Lake, this paper analyzed the annual fluctuation of air temperature, precipitation, and aridity index as well as the effects of this fluctuation on the phenology and aboveground production of Poa crymophila, a dominant grass species in this region’s alpine meadow grassland. In the region, the mean annual air temperature increased significantly at a rate of 0.512 ℃·10 a^-1, with much higher increment in autumn and winter than in spring and summer. The annual precipitation increased, mainly in spring and autumn and with an about 9-year cycle. The aridity index in the growth season of P. crymophila had an increasing trend, and from the late 1990s to 2010, it was obviously getting warmer and drier. The stages of turning green, heading, flowering, and seed maturing of P. crymophila were in advance, yellowing stage delayed, and thus, the whole growth period of this grass prolonged. The simulated results with Logistic model indicated that the growth speed of the grass was the maximum on the 72nd after turning green, being 0.29 cm plant height per day. The growth speed turned from slow to rapid from the 49th day after turning green, and turned from rapid to slow from the 95th day after turning green, with a rapid growth period of 46 days. The plant height and aboveground biomass of P. crymophila increased year by year. The production of P. crymophila was most sensitive to the heat in May. With a 1 ℃ average tenday temperature increase, the production would be increased by 20-30 kg·hm^-2. Water availability was crucial for P. crymophila during its heading and flowering stages. The production of the grass would be increased with the increase of precipitation.

Responses of grassland net primary productivity in western Songnen Plain of Northeast China to climate change and human activity.

LUO Ling1, WANG Zong-ming1**, MAO De-hua1,2, LOU Yan-jing1, REN Chun-ying1, SONG Kaishan1

2012, 31(06):  1533-1540. 

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By the methods of correlation analysis and buffer analysis, and taking two main climate factors (air temperature and precipitation) and two main human activity areas (road and residential land) into account, this paper studied the effects of climate change and human activity on  grassland net primary productivity (NPP) in western Songnen Plain in 2000-2009. In the past ten years, the mean air temperature in the study area was 5.39 ℃, which increased from north to south, and the mean precipitation was 378 mm, which decreased from northeast to southwest. The grassland NPP increased with the increase of air temperature and precipitation. Compared with air temperature, precipitation affected NPP more obviously, which accorded with the special climate conditions of water shortage in western Songnen Plain. The difference in the NPP was not significant at yearly scale but extremely significant at monthly scale, indicating that time scale had remarkable effects on the statistical significance. The effects of road and residential land on the NPP were completely opposite. The closer to the road, the larger area the grassland with good plant growth, which could related to the appropriate management measures and the ways of local human activities; while the further to the residential land, the weaker the human activities intensity or their capabilities in affecting the grassland, the better the plant growth on the grassland. Compared with road, residential land had more obvious effects on the grassland NPP, possibly due to the higher density of residential land and the more frequent building construction, reclamation, and grazing caused by population increase.

Potential effects of urban planning on local climate in Binhai New Area of Tianjin City, North China.

LI Ming-cai1**, XIONG Ming-ming1, HUANG He2, REN Yu1, ZHANG Hao2

2012, 31(06):  1541-1547. 

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In order to understand the potential effects of urban planning on local climate, the Nangang industrial area in the south Binhai New Area of Tianjin was taken as a case, and a boundary layer model was applied to simulate the variations of climatic environmental elements before and after urban planning, with the possible effects on the petrochemical industry in this area analyzed. The results showed that urban planning had obvious effects on the air temperature in all four seasons. After the planning, the air temperature in spring mostly showed decrease, with the largest decrement of 0.6 ℃ at 1:00 pm, and the air temperature in winter, summer, and autumn showed a pattern of apparent decrease at daytime and the largest increase at night. The variation range of the air temperature was larger in winter than in summer and autumn. Urban planning had obvious effects on the enhancement of wind speed in winter, spring, and autumn, with the amplitude of 0.6 m·s^-1, 0.4 m·s^-1, and 0.6 m·s^-1, respectively. The wind speed in summer after urban planning only had a weak enhancement (0.2 m·s^-1). The variation of air temperature and the enhancement of wind speed would benefit the petrochemical industry in this area, because the temperature decrease at daytime, especially in summer, would increase the human comfort and reduce the risks of petrochemical industry, and the enhancement of wind speed would be favorable to the diffusion of pollutants. Overall, urban planning made the local climatic environmental elements have a great change, which would be beneficial to the production of petrochemical industry.

Relationships between sand-accumulation belt and environmental factors along oasis edge of Hexi, Gansu Province of Northwest China.

CHANG Zhao-feng1,2,3**, ZHANG Jian-hui1,2,3, TANG Jin-nian1,2,3, WANG Qiang-qiang1,2,3, ZHANG Da-biao1,2,3, ZHU Shu-juan1,2,3, ZHANG Guo-zhong1,2,3

2012, 31(06):  1548-1555. 

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The formation of sand-accumulation belt along oasis edge is a new scientific concern. In Hexi of Gansu, a sand-accumulation belt has been formed along oasis edge for almost 50 years as a result of desert control efforts. To understand the relationships between the formation of this belt and environmental factors, an investigation was conducted along the oasis edge from the east to the middle and west of Hexi corridor. The average height of the sandaccumulation belt is 12.77 m, and the average width is 308.48 m. There exists a significant positive correlation between the belt width and height, and the belt height and its increasing rate are significantly positively correlated with the mean annual precipitation and wind speed. Precipitation is the key factor deciding the belt height, while the mean annual wind speed is the secondary one. To set up a wheat straw sand barrier at the top of big sand dunes could continuously heighten the sand-accumulation belt.

Location stability and quantification stability of landscape change along the urban-rural gradient of Nanjing metropolitan region.

CHEN Hao, LIU Mao-song**, XU Chi, YANG Xue-jiao, HUANG Tao

2012, 31(06):  1556-1561. 

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By using multi-temporal Landsat TM images and the Kappa index, this paper studied the location variation and quantification variation of the landscape elements (except for mountains and large water bodies) along the urban-rural gradient of Nanjing in 1998-2008, aimed to quantify the landscape stability and spatial differentiation during urbanization. In the study area, cultivated land presented high quantification stability but low location stability, whereas settlement had high location stability but low quantification stability. Both the location stability and the quantification stability of the waters were high, but those of forested land and other types of landscape elements were low. Along the urban-rural gradient, landscape showed increasing location stability but declining quantification stability with the increasing level of urbanization. For the urbanized area, quantification stability increased rapidly, and the composition and spatial features of landscape elements were prone to be steady. Settlement and cropland showed substantial variations in location stability and quantification stability in different zones along the urban-rural gradient, while waters and forestland were less affected in terms of the location stability and quantification stability in the zones.

Construction of domain ontology for large-scale ecosystem nitrogen flux calculation.

HAN Jia-jia1, MIN Yong1, GE Han-liang1, JIN Xiao-gang2,GAO Bo3, GU Bao-jing1, GE Ying1, CHANG Jie1**

2012, 31(06):  1562-1570. 

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At present, large-scale ecosystem nitrogen flux calculation mainly depends on quasi-empirical models which quantify the nitrogen fluxes by using empirical formulas based on various kinds of collected parameters. However, quasiempirical models have several limitations in application, including (1) completeness of calculation cannot be ensured due to the lack of variables, (2) uncertainty analysis is difficult, and (3) data sharing is lack of standardization. Ontology is a semantic model for describing concepts and their relations, which can unify and enrich the description of data to improve data sharing. In addition, the reasoning mechanism and hierarchy of ontology can provide automatic reasoning for quasi-empirical models to find out unavailable variables and conduct uncertainty analysis. In this paper, the domain ontology for the quasi-empirical models of nitrogen flux calculation (NFCO) was constructed, and a framework of automatic reasoning and uncertainty analysis based on NFCO was proposed, which would improve the quality of large-scale ecosystem nitrogen flux calculation, and build a solid foundation for establishing large-scale ecosystem nitrogen cycle database.  

Responses of ectomycorrhiza to drought stress: A review.

WANG Ju-gang1, ZHENG Rong1,2, BAI Shu-lan1**, LIU Sheng1, YAN Wei3

2012, 31(06):  1571-1576. 

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This paper reviewed the research progress in the responses of ectomycorrhiza to drought stress and related resistance mechanisms from the aspects of ectomycorrhizal fungi, ectomycorrhizal symbiote, and indirect effects of ectomycorrhiza. The future research directions on the ectomycorrhiza in China were also prospected. Drought stress can inhibit the growth of ectomycorrhizal fungi, and decrease the fungal diversity in ectomycorrhizal fungal communities. Under drought stress, the ectomycorrhizal fungal sporocarp can use deep (>30 cm) soil water. The ratio of sporocarp surface to its volume is an important factor for the screening of drought resistant strains of ectomycorrhizal fungi in arid region. Ectomycorrhizal symbiote can resist drought stress by morphological change, increasing water absorption, and improving related metabolisms such as the photosynthesis, reactive oxygen species, and hormones of plants. It would be beneficial for host plants to resist drought stress when the ectomycorrhiza promoted the growth of host plants and other rhizosphere microbes, and increased the soil carbon sink. It was suggested that the ectomycorrhizal research in China should focus on the screening of excellent fungi-tree combination in arid region, and pay more attention to the investigation of native ectomycorrhizal fungal resources. In the future research, an impetus should be made to the molecular biological research.

Insect diversity in wetland vegetation succession: A review.

SU Lan1,2, HUANG Jun-hao1, WU Ming2, WU Hong1**

2012, 31(06):  1577-1584. 

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Insect diversity is an important part of wetland biodiversity, which is closely related to the vegetation in wetland ecosystem. Many environmental factors affect wetland insect diversity, and vegetation succession is the key factor. Due to the sensitivity to wetland environmental change, insect diversity is gradually applied as an indicator for the monitoring and evaluation of wetland quality, and crucial for the study of wetland conservation and restoration. This paper summarized the research progress in the vegetation succession, dominant insect groups, and variation patterns and affecting factors of insect diversity on different wetland types. The application of insect diversity as an indicator for wetland quality monitoring and evaluation was discussed, and the research gaps and priorities concerning wetland insect diversity were pointed out.

Research advances in eco-environment assessment using dragonfly as a bioindicator.

YU Xin1,2, BU Wen-jun1, ZHU Lin2**

2012, 31(06):  1585-1590. 

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Dragonfly, due to its wide distribution, in-depth research and easy to sample, is an ideal bioindicator for eco.environment assessment. In recent decades, more and more related researches are using dragonfly to assess ecoenvironment. In this review, the related researches were generalized into five types, i.e., general environmental assessment, environment pollution degree assessment, environmental improvement assessment, climate change assessment, and large-scale environmental assessment, and a brief introduction for each type of the researches was given. The current status and deficiency of the researches in China were discussed, and the broad prospects of using dragonfly as a bioindicator for eco-environment assessment were analyzed through the comparison of the superiority of this bioindicator than the others. It was point out that to build up a thoroughly sourced database of dragonfly diversity in China and to develop specific assessment methods could be the most important things to make progress. Using dragonfly as a bioindicator to assess ecological environment would be low-cost, high-efficient, and environmentally friendly, not only important but also necessary to the needs of China today’s economic development.

Research advances in biodiversity remote sensing monitoring.

HU Hai-de1,2, LI Xiao-yu3, DU Yu-fei2,3, ZHENG Hai-feng1, DU Ben-xu4, HE Xing-yuan1，3**

2012, 31(06):  1591-1596. 

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Quickly and regularly monitoring and assessing regional biodiversity is of great significance for biodiversity research and conservation. In recent years, remote sensing technology is extensively applied in biodiversity research, and can provide regional, continental, and global biodiversity information. This approach is low cost and high data consistency, and updated regularly. This paper introduced the principles and advantages of remote sensing in biodiversity research, and summarized the main application aspects of biodiversity remote sensing in practice, including landscape indices, NDVI, spectral variation hypothesis (SVH), and hyperspectral remote sensing, with the focus on the analysis of the advantages and disadvantages of these application aspects and the recent research advances in SVH research and optimal band selection. The deficiencies in the remote sensing biodiversity research were pointed out, and the development trend in this research field, such as models, remote sensors, and scale effect, were prospected.

An approach for tracing landscape change based on landscape graph and bioenergetics.

HAN Ling-yun1, XU Zhen1, RUAN Hong-hua1**, QU Xiao-yi1, CHEN Gui-juan2, FENG Yu-qing2, JIN Yu-hua1

2012, 31(06):  1597-1604. 

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To apply landscape pattern analysis in landscape planning and management is of theoretical and practical significance for maintaining regional ecological safety. Taking a riparian zone in the suburb of Suzhou, Jiangsu Province of East China as an example, an attempt was made to integrate landscape graph and bioenergetics to explore a simple, intuitionistic, and effective approach to trace the landscape change and evaluate the ecological consequences of land use change, aimed to supply basis for the decision-making of sustainable landscape planning and management. With the support of ArcGIS and the four periods Google Earth images, the landscape graphs of the riparian zone were delineated, and the changes of the amount, type, and spatial conformation of nodes and linkages were mapped to trace the variation course of the landscape in the zone and to interpret the ecological meanings of the landscape graphs. The landscape of the riparian zone had endured degradation, with an evident trend of landscape fragmentation, obvious decrease of natural landscape connectivity, extinction of small rivers and ponds, and inadequate riparian buffers. The detection of key ecological nodes and linkages could provide invaluable insights of taking particular measures for natural landscape conservation, and balancing contradictions of protection and development.