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    18 December 2014, Volume 25 Issue 12
    Predicting the impact of global warming on the geographical distribution pattern of Quercus variabilis in China.
    LI Yao, ZHANG Xing-wang, FANG Yan-ming
    2014, 25(12):  3381-3389. 
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    The geographical distribution of Quercus variabilis in China with its climate characteristics was analyzed based on DIVA-GIS which was also used to estimate the response of future potential distribution to global warming by Bioclim and Domain models. Analysis results showed the geographical distribution of Q. variabilis could be divided into 7 subregions: Henduan Mountains, YunnanGuizhou Plateau, North China, East China, LiaodongShandong Peninsula, Taiwan Island, and QinlingDaba Mountains. These subregions are across 7 temperature zones, 2 moisture regions and 17 climatic subregions, including 8 climate types. The modern abundance center of Q. variabilis is Qinling, Daba and Funiu mountains. The condition of mean annual temperature 7.5-19.8 ℃ annual precipitation 471-1511 mm, is suitable for Q. variabilis. Areas under the receiver operating characteristic curve (AUC values) of Domain and Boiclim models were 0.910, 0.779; the former predicted that the potential regions of high suitability for Q. variabilis are Qinling, Daba, Funiu, Tongbai, and Dabie mountains, eastern and western YunnanGuizhou Plateau, hills of southern Jiangsu and Anhui, part of the mountains in North China. Global warming might lead to the shrinking in suitable region and retreating from the south for Q. variabilis.
     
    Vertical patterns of plant species diversity in the Baishuijiang Nature Reserve: Explanation of area, climate and boundary constraint. 
    ZHENG Zhi1, GONG Da-jie1, ZHANG Qian2, ZHAO Hai-bin1
    2014, 25(12):  3390-3398. 
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    The linear regression models and variation partitioning method were used to analyze the relative and pure effects of area, climate, and boundary constraint on altitudinal patterns of plant species diversity in the Baishuijiang Natural Reserve. The results showed that diversities of overall plant species and different group species exhibited humpedshaped patterns and the peaks were below the midpoint of the elevation span. The patterns were shaped by all factors together. The explanatory power of waterenergy  hypothesis for the pattern was the strongest. Area acted as a secondary factor the patterns. Boundary constraint effect was a complementary mechanism to explain the plant species diversity altitudinal patterns in Baishuijiang region. The explanatory powers of boundary constraint for differentrange species were clearly different. With the increase of species range, boundary constraint showed an increasingly strong correlation with richness patterns.
    Effects of forest gap size on the architecture of Quercus variablis seedlings on the south slope of Qinling Mountains, West China.
    YU Bi-yun, ZHANG Wen-hui, HE Ting, YOU Jian-jian, LI Gang
    2014, 25(12):  3399-3406. 
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    Typical sampling method was conducted to survey the effects of forest gap size on branch architecture, leaf characteristics and their vertical distribution of Quercus variablis seedlings from different size gaps in natural secondary Q. variablis thinning forest, on the south slope of Qinling Mountains. The results showed that gap size significantly affected the diameter, crown area of Q. variablis seedlings. The gap size positively correlated with diameter and negatively correlated with crown area, while it had no significant impact on seedling height, crown length and crown rates. The overall bifurcation ratio, stepwise bifurcation ratio, and ratio of branch diameter followed as large gap > middle gap > small gap > understory. The vertical distribution of firstorder branches under different size gaps mainly concentrated at the middle and upper part of trunk, larger diameter firstorder branches were mainly distributed at the lower part of trunk, and the angle of firstorder branch increased at first and then declined with the increasing seedling height. With the increasing forest gap size, the leaf length, leaf width and average leaf area of seedlings all gradually declined, while the average leaf number per plant and relative total leaf number increased, the leaf lengthwidth ratio kept stable, the relative leaf number was mainly distributed at the middle and upper parts of trunk, the changes of leaf area index was consistent with the change of the relative total number of leaves. There was no significant difference between the diameters of middle gap and large gap seedlings, but the diameter of middle gap seedlings was higher than that of large gap, suggesting the middle gap would benefit the seedlings regeneration and highquality timber cultivation. To promote the regeneration of Q. variabilis seedlings, and to cultivate highquality timber, appropriate thinning should be taken to increase the number of middle gaps in the management of Q. variabilis forest.
    Point pattern analysis of Populus euphratica population in the lower reaches of Heihe River.
    ZHANG Lan1, ZHANG Hua1,2, ZHAO Chuan-yan2
    2014, 25(12):  3407-3412. 
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    Taking Populus euphratica population in the lower reaches of Heihe River as the research object, through field investigation, using spatial point pattern analysis method of Ripley’s K function, and combined the macro  geographical environment with micro point pattern, we analyzed the spatial distribution pattern of P. euphratica population at different scales. The results showed that P. euphratica density decreased with the increasing distance away from the river, and its density was higher along the East River than along the West River on the whole. The distribution pattern of P. euphratica population varied with spatial scale which was mainly aggregated at mesoscale of 5-12 m, randomly distributed at smallscale of 0-2 m and largescale of 38-40 m, and very few was evenly distributed. P. euphratica populations were mainly aggregated away from the river, and the aggregation intensity tended to increase with the distance, while it tended to spread and turned into a random distribution at the farther distance. Research showed that the ecological linkages of P. euphratica populations strongly depended on space scale, and the surface soil moisture and groundwater depth were the main factors influencing the spatial distribution of P. euphratica populations.
    Responses of plant functional traits to micro-topographical changes in hilly and gully region of the Loess Plateau, China.
    YANG Shi-suo1, WEN Zhong-ming1, MIAO Lian-peng2, QI De-hui2, HUA Dong-wen3
    2014, 25(12):  3413-3419. 
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    Plant functional traits are closely tied to the performance of plants in specific microenvironments, and reflect their ability to adapt to those microenvironments. In areas with complex topography, analyzing the responses of plant functional traits to micro-topographical changes is crucial to understanding the adaptive strategies of plants in diverse environments. This paper analyzed fluctuations in soil nutrients as well as correlations between plant functional traits and changes in topography at the family and community levels in selected natural vegetation communities in the forest-steppe zone of the loess hilly and gully region in Loess Plateau of China. Significant differences in plant functional traits were primarily driven by the phylogenetic background or species composition of the community. Slope aspect exerted less impact while slope positions had no significant effect on plant traits at the community level. No significant changes in plant functional traits were observed with changes in topography at the community level. However, leaf nitrogen and root nitrogen contents of Leguminous and Compositae species differed significantly with slope positions. The root tissue density of Graminaceous species differed significantly with slope positions. Root density exhibited significant positive correlations with soil nutrient and carbon contents at the community level. Both leaf nitrogen and root nitrogen contents of Leguminous species were positively correlated with soil phosphorus content, while leaf nitrogen and root nitrogen contents of both Graminaceous and Compositae species were significantly positively related to soil nitrogen content. The results demonstrate the different responses of species of different families to changes in micro-topography and their distinctive adaptive strategies to the environment.
    Estimation of seasonal changes in leaf area index based on optical methods in spruce-fir valley forest.
    LIU Zhi-li, JIN Guang-ze
    2014, 25(12):  3420-3428. 
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    The seasonal changes in LAI were respectively measured using digital hemispherical photography (DHP), LAI-2000 plant canopy analyzer (indirect methods) and litter collection method (direct method) in spruce-fir valley forest in the Xiaoxing’an Mountains, China. In addition, we constructed the relationships between LAI from direct method and that from indirect methods in different seasons. The results showed that LAI from DHP underestimated LAI from direct method by 40%-48% in the whole study period, and the underestimation range for LAI-2000 plant canopy analyzer was 15%-26%. LAI from direct method and that from DHP or LAI-2000 plant canopy analyzer all correlated significantly in different seasons, and the relationships between LAI from direct method and that from DHP or LAI-2000 plant canopy analyzer all could be merged into three classified prediction models after testing, i.e., A, B and C, which were able to predict LAI in May and November, June, September and October, and July and August, respectively. This study laid a foundation for effective and accurate measurement of seasonal changes in LAI for coniferous forest in subsequent studies.
    Forest landscapes’ spatial point patterns and associations based on Ripley L and O-ring functions.
    DONG Ling-bo1, LIU Zhao-gang1, ZHANG Bo2, YUAN Ye1, SUN Yun-xia1
    2014, 25(12):  3429-3436. 
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    Based on the data of forest resource inventory in Pangu Forest Farm of Great Xing’an Mountains in northeastern China, the spatial distribution pattern and associations of the main forest landscape types [natural Larix gmelini forest (NLG), natural Betula platyphylla forest (NBP), natural coniferous mixed forest (NCM) and natural mixed broadleafconifer forest (NCB)] were studied by the two main spatial point pattern analysis methods (Ripley L and O-ring functions). The results showed that the spatial distribution pattern of the four forest landscape types were all consistent with each other the whole, which were all significantly clumped at small scale, and then mainly the obvious characteristics of random distribution with the increase of scale. Spatial associations of the four forest landscape types differed significantly with the Ripley L and O-ring functions. The results of Ripley L function showed that NLG and NCB, NBP and NCB had the obvious negative correlations at small and medium scales, and then mainly showed the trend of noncorrelations or even positive correlations at medium and large scales, however, there were significantly negative correlations for the other forest landscape types at all the research scales. Unlike the results of Ripley L function, the results of O-ring function showed that the main forest landscape types were all significantly negative at small scale, no at medium scale, and positive at large scale with each other. Meanwhile, there were also significant differences for the spatial distribution patterns and associations for the same forest landscape type (or group) at the same level of scale with two different methods, and the rate of consistency of the two methods  at all levels of scale mainly exist three forms, i.e. basically remain unchanged, reduced firstly and then increased, and almost always reduced, respectively.
    Taxonomic diversity of the plant communities in Pangquangou Nature Reserve, Shanxi Pro-vince, China.
    ZHAO Xiao-na1, QIN Xiao-juan2, DONG Gang1,2, ZHANG Feng1,2
    2014, 25(12):  3437-3442. 
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    In order to explore the relationship between the taxonomic diversity of plant communities’ and environmental factors in Pangquangou Nature Reserve, Shanxi Province, 33 stands of the plant communities and environmental information were investigated, respectively. Moreover, the taxonomic variability index (Λ+) and the average taxonomic differences index (Δ+) of the communities were analyzed as well as the relationships between Λ+ and Δ+ with environmental factors were discussed. The results showed that the average values of Λ+ and Δ+ were 270 and 76.5, respectively.  Λ+ was negatively correlated with altitude and slope, Δ+ and latitude had a significant positive correlation, and  Δ+ and slope had a significant negative correlation. Based on the distributions of the 33 stands in the confidence funnel, the plant communities had a higher taxonomic diversity in Pangquangou Nature Reserve, which resulted from that the plant resources and eco-environment had been effectively conserved with little disturbance from human activities since the establishment of the nature reserve for more than 30 years.
    Kapok capsule formation and fiber development process in Yuanjiang dryhot valley.
    ZHAO Gao-juan, GE Luan, MA Huan-cheng, YANG Jian-jun, HUANG Dong, PING Pan
    2014, 25(12):  3443-3450. 
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    This study explored the capsule formation and fiber development process of kapok which is a tree in Yuanjiang dry-hot valleys (DHV) using the methods of paraffin section and scanning electron microscopy. The result showed that formation process of kapok capsule can be divided into four stages: the capsule formation within 5 days after anthesis (DAA), the capsule mass period from 5 to 35 DAA, the capsule dehydration period from 35 to 50 DAA, and the capsule bursting period after 50 DAA. The kapok fiber was developed via endocarp cells differentiation (0-2 DAA), swelling (2-5 DAA), bulging (5-10 DAA), fiber elongating (10-40 DAA), and divorcing from pericarp (40-50 DAA). During the development, the length and projection width of fiber increased as a power function, and their daily average growth rates reached the maximums at 20 DAA. Fiber fresh mass substantially increased and then reduced, and the daily average growth rate reached the maximum in the period from 25 to 30 DAA. Fiber dry mass gradually increased and reached the maximum growth rate in the period from 20 to 25 DAA. The seed and fiber continually increased their mass after 30 DAA, but the pericarp mass declined with its dehydration and aging. Compared with cotton, it was easy to separate fiber from kapok capsule inner wall because of small adhesion power between kapok fiber and capsule inner wall. The period from 5 to 35 DAA was critical for the fiber development and growth. Therefore, water and fertilizer management should be concentrated at this stage. The capsule should be harvested at 50 DAA because the fiber began to divorce from the pericarp.
    Structure characteristics of natural nests and its implication to artificial nest frame design for Ciconia boyciana
    WEI Yi-qing, CUI Guo-fa
    2014, 25(12):  3451-3457. 
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    Artificial nest can improve the breeding success of birds in the field, and it has been proved to be more effective to endangered species. We surveyed the structure characteristics of natural nest and the status of the use of artificial nests for oriental white stork, Ciconia boyciana, in Honghe National Nature Reserve, Heilongjiang Province. Differences were investigated among the structure characteristics of the used and  unused artificial nests, and natural nests based on one-way ANOVA. It was observed that significant differences in the diameter of nest branch, the vertical angle between nest branch, the height of the jointthe height of the nest above ground exited in  different nest types. On account of the structure characteristics of the natural nests of C. boyciana, the suitable diameter of nest pillar for artificial nest frame should be 15.0-25.0 cm with the height of 5.0-12.0 m, which would be better if they were constructed by some acidresistant materials, e.g. cement. The number of nest stands should be 3-4 individuals with the diameter of 9.0-12.0 cm, the vertical angle of 45°-60°, and the length of 90.0-140.0 cm.
     
    Effects of grazing on spatial distribution relationships between constructive and dominant species in Stipa breviflora desert steppe.
    2014, 25(12):  3469-3474. 
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    The effects of grazing on spatial distribution relationships of constructive species (Stipa breviflora) and dominant species (Cleistogenes songorica and Allium polyrhizum) in the desert steppe were analyzed by different analysis methods. The results showed that the landscape characteristic of S. breviflora + C. songorica + A. polyrhizum community was mainly affected by soil properties and inherent properties of populations. The spatial distribution variability influenced by continuous grazing (CG) was in order of A. polyrhizum > C. songorica > S. breviflora. The influence of CG upon the density of S. breviflora and A. polyrhizum was notable, while little influence upon the density of C. songorica was observed. S. breviflora density increased with the increasing C. songorica density in CG area, whereas it increased firstly and then decreased with the increasing C. songorica density in enclosed area (CK). S. breviflora density decreased with the increasing A. polyrhizum density in CG and CK area. It was concluded that there was density effect for plant interspecific relationships which could disappear with the presence of outside interference. Plant interspecific relationships were multiple with the difference in populations or interference conditions.
    Endophytic fungal communities of Stipa sp. roots in different types of steppes in northern China.
    ZHANG Shao-peng1,2, XU Ting1,2, YANG Li-qiang1,2, SONG Yu3, LI Xin-yu1, ZHANG Hui-wen1
    2014, 25(12):  3475-3482. 
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    In order to explore the endophytic fungal communities of Stipa sp. roots in different types of steppes in the north of China, root tissues of Stipa sp. were collected from six different types of steppes, i.e., subalpine meadow, alpine meadow, Gobi desert, desert steppe, typical steppe, and meadow steppe across Xinjiang, Gansu and Inner Mongolia. A total of 213 isolates were obtained and sequenced, which were divided into 51 operational taxonomic units (OTUs) at the 97% similarity threshold and classified to 4 phyla, 7 classes, 23 families and 27 genera. Ascomycota was found to be the predominant flora (93.4% of the total isolates) at the level of phylum and distributed in all the six steppe types. The dominant genera other than Fusarium (41.3 of the total isolates) in the six steppe types were different, such as Microdochium in subalpine meadow, Saccharicola and Aureobasidium in alpine meadow, Curvularia and Rhizopus in Gobi desert and Trichoderma in typical steppe. The endophytic fungal community from the alpine meadow contained the most abundant groups at the level of genus and phylum, and had the highest Margalef index, Shannon index and second highest evenness index after the desert steppe. By contrast, the lowest Margalef index was observed in the desert steppe and the lowest Shannon index and evenness index were found in the typical steppe. Furthermore, endophytic fungal communities from alpine meadow and desert steppe showed low similarity coefficients (0.12-0.25 and 0.13-0.22, respectively) with other steppe types. However, the similarity coefficients among the other four steppe types were relatively high, especially between the typical steppe and the meadow steppe (0.60). Redundancy analysis (RDA) showed that the altitude and latitude were the main environmental factors affecting endophytic fungal community distribution in the roots of Stipa sp. in the six steppe types.
    Identification and conservation assessment of suitable habitats for Tibetan antelope in the alpine desert, QinghaiTibet Plateau.
    ZHUGE Hai-jin1, LI Xiao-wen1, ZHANG Xiang2, GAO Feng2, XU Dong-hua2
    2014, 25(12):  3483-3490. 
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    As a flagship and one of most endangered ungulates in the alpine desert of QinghaiTibet Plateau, the habitat conservation of Tibetan antelope (Pantholops hodgsonii) is vital to sustain its longterm population existence. In consideration of key habitat factors of the Tibetan antelope (i.e., food, topography and water source) as well as human interference factors like roads and settlements, the habitat suitability was modeled, and potential and valid suitable habitats were identified for Tibetan antelope in the alpine desert, QinghaiTibet Plateau. Furthermore, the conservation proportion index and conservation efficacy index were developed to facilitate the conservation assessment of three national reserves (i.e., Altun Mountain, Kekexili and Qiangtang) and their associated functional zones in the study area. The results showed that potential and valid area of suitable habitat across overall study area were 2.84×105 and 2.08×105 km2 respectively, with 16.1% of suitable habitat loss by human disturbance. At reserve level, the potential suitable habitats of Altun Mountain, Kekexili and Qiangtang were 2.01×104, 3.13×104 and 1.26×105 km2, which however decreased by 12.9%, 10.2% and 21.1% human disturbance respectively, indicating a prominent habitat fragmentation especially in Qiangtang National Nature Reserve (NNR). Although three NNRs had captured nearly 2/3 of the potential/valid suitable habitats with favorable conservation efficacy, there were still obvious conservation gaps outside the existing reserve network. At the functional zone level, buffer and experimental zones also showed significant conservation proportion and efficacy besides the core zone. Our research highlighted the necessity to optimize the existing reserve system by filling the conservation gaps, restructuring the functional zones and safeguarding the potential refuge habitats for those endangered ungulates in face of climate change.
    Effect of straw-returning on the storage and distribution of different active fractions of soil organic carbon.
    WANG Hu1,2, WANG Xu-dong1,3, TIAN Xiao-hong1,3
    2014, 25(12):  3491-3498. 
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    The impacts of straw mulching and returning on the storage of soil dissolved organic carbon (DOC), particulate organic carbon (POC) and mineral associated organic carbon (MOC), and their proportions to the total organic carbon (TOC) were studied based on a field experiment. The results showed that compared to the treatment of wheat straw soilreturning (WR), the storage of TOC and MOC decreased by 4.1% and 9.7% respectively in 0-20 cm soil in the treatment with wheat straw mulching (WM), but the storage of DOC and POC increased by 207.7% and 11.9%, and TOC and POC increased significantly in 20-40 cm soil. Compared to the treatment with maize straw soilreturning (MR), the storage of TOC and MOC in the plough pan soil of the treatment with maize straw mulching (MM) increased by 13.6% and 14.6%, respectively. Compared to the WR-MR treatment, the storage of TOC and MOC in top soil (0-20 cm) significantly decreased by 8.5% and 10.3% respectively in WM-MM treatment. The storage of TOC and POC in top soil was significantly higher in the treatments with maize straw soilreturning or mulching than that with wheat straw. Compared to the treatment without straw (CK), the storage of TOC in top soil increased by 5.2% to 18.0% in the treatments with straw returning or mulching in the six modes (WM, WR, MM, MR, WM-MM,WR-MR)(P<0.05), but the storage of TOC in the plough pan soil decreased by 8.0% to 11.5% (P<0.05) except for the treatments of WM and MM. The storage of DOC and DOC/TOC ratio decreased significantly in top soil in the treatments with straw mulching or returning in six modes. The storage of POC and POC/TOC ratio in WM and WM-MM treatments, MOC and MOC/TOC ratio in WR treatment, increased significantly in top soil. In the other three treatments with straw mulching and returning (MM, MR, WR-MR), the storage of POC and MOC increased significantly in top soil. These results suggested that straw mulching had the potential to accumulate active organic carbon fraction in soil, straw soilreturning had the potential to accumulate stable organic carbon fraction. Considering organic carbon sequestration in cropland in the region of Guanzhong plain, maize straw mulching or soilreturning was better than wheat straw, and wheat straw and maize straw soilreturning (WR-MR) were better than wheat and maize straw mulching (WMMM).
    Effects of different fertilization ways on the contents of N, P, K in new shoots and photobiological characters of tea tree.
    LUO Fan1,2, ZHANG Ting2, GONG Xue-jiao2, DU Xiao1, MA Wei-wei2
    2014, 25(12):  3499-3506. 
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    The variety of the contents of N, P, K and photo-biological characters in a bud and two leaves tea tree new shoots were determined to investigate the effects of different fertilization ways, i.e. single or combined N, P, K fertilizer. The regression equations of net photosynthetic rate (Pn) of tea tree in spring, summer and autumn were set up by stepwise regression analysis. The results showed that fertilization ways significantly affected the contents of N, P, K in new shoot. In the same fertilization ways, the contents of N, P in the new shoot was less in summer and autumn than in spring, but the content of K was in contrast. Combined application of N, P and K fertilizer improved Pn of the tea trees in spring. Single application of P fertilizer inhibited the Pn of the tea trees in summer and autumn, while single application of N fertilizer significantly improved it. In the same fertilization ways, the Pn of the tea trees in summer and autumn was higher than in spring. The stomatal conductance (gs) and  transpiration rate (Tr) had positive correlations to Pn in summer and autumn. Regression and correlation analysis showed that the physiological factors affecting Pn of the tea trees varied with seasons, and the common factors were the Ci and the content of P. Ci had some subduction to Pn , and it was improved by the content of phosphorus.
    Corn straw composting in the field and in situ fertilizer effect.
    CHEN Ya-nan1, ZHANG Chang-hua2, LIANG Yong-jiang2, CHEN Qi-di1, SHI Jun-xiong3, DU Ru-wan4, LUO Jian-jun5, YUAN Ling1
    2014, 25(12):  3507-3513. 
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    According to the fact that corn straws remain or burned in the field in hilly and mountainous areas of Southwest China, which causes organic matter waste and serious atmospheric pollution, it is necessary to develop an efficient method to compost the corn straws. In the present experiment, corn straws were placed on the landside and land corner for composting with thermophilic cellulous bacteria inoculated, chemical nitrogen and nitrogen absorption agent added, and then covered with polyethylene film (biocomposting). Thereafter, fluecured tobacco grown in the same land was fertilized with the compost to study the fertilizer effect. The results showed that the temperature in biocompost increased quickly (over than 35 ℃ within 2 to 3 days) but decreased slowly compared to natural composting (control). In the biocompost, temperature over than 50 ℃ lasted for about 15 days and the number of bacteria was 100 to 1000 times higher than in the control despite that microbial groups decreased in the high temperature period. After 90 days of biocomposting, corn straws contained water less than 25% with pH 6.14 and showed brown or black color and fragmental or farinose physical state, indicating good decomposition and humification. Meanwhile, the active organic matter and nutrients, including N, P and K, were significantly increased. The yield, mean price, economical output of fluecured tobacco leaves were increased and the leaf quality was improved by application of chemical fertilizers plus the compost at the ratio of 1:1. Therefore, biocomposting could utilize efficiently corn straws and eliminate air pollution, which is worth popularization in hilly and mountain areas.
    Discussion on the calculation method of nitrogen use efficiency (NUE) in long-term field experiments under wheat and maize rotation systems.
    YANG Xian-long1,2, LU Yong-li1,2, LI Ru3, TONG Yan-an1,2
    2014, 25(12):  3514-3520. 
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    In recent years, some  scholars from China have deeply discussed about the concept, connotation and calculating method of nitrogen use efficiency (NUE), and have raised questions and also put forward some improved methods for NUE calculation in cultivated lands. In this paper, we compared advantages and disadvantages of these improved NUE calculation methods by using the data from a 5-year positioning field experiment under a wheatmaize rotation system. The results indicated that it made mistakes when the traditional subtraction method was used to calculate NUE for wheat season and maize season separately, since the soil fertility level of experimental plots had differed significantly from each other after several seasons or years of different fertilization managements. Additionally, the calculated NUE increased markedly with the cropping season going, thus making it difficult to mirror the actual situation of N utilization in cultivated lands. For the wheatmaize rotation system, the cumulative NUE calculation method considered wheat season and maize season as a whole part, and skillfully avoided mistakes which could be caused by inhomogeneity  of soil fertility levels between experimental plots. Moreover, the calculated NUE were comparably smaller, with smaller coefficient variations (CVs), in contrast with the traditional subtraction method. The NUE calculated by using the ratio method were bigger, with the smallest CVs, than that computed by using the cumulative calculation method. The soil N balance method took a thoughtful consideration about the budgets and losses of soil nutrients before and after crop growth, but obtained the largest values of NUE and CVs within these methods.
    Changes in the growth and photosynthesis of cotton seedlings under progressive drought after saltwater irrigation.
    MA Shu-jie1, BAI Xin-fu1, QI Lin1, ZHU Jian-jun1, ZHANG Zhen-hua2
    2014, 25(12):  3521-3526. 
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    Pot grown cotton plants were watered with saltwater (NaCl solutions of different concentrations), followed by a duration of progressive drought stress. The changes in plantlet growth, photosynthetic rate, chlorophyll fluorescence were measured, and the water status of the plantlets, such as relative water content, water potential, osmotic potential, the Na+ and K+ contents in leaves during drought were measured and analyzed, in order to get an insight into the role of Na+ played in the adaptation of cotton to drought stress. The results showed that the growth of the plantlets was significantly inhibited, the net photosynthetic rates were remarkably lowered by the drought stress, but the plant height, biomass, net photosynthetic rate and Fv/Fm values in the cotton plants watered with 25-100 mmol·L-1 NaCl solution under drought stress were significantly higher than those watered with water under the same intensity of drought stress. Meanwhile, the soil and leaf relative water content, cell turgor, Na+ concentration in plants watered with 25-100 mmol·L-1 NaCl solution were all significantly higher compared with that of plants watered with water, but the plant water potential and tissue osmotic potential were significantly lower with the decrease in tissue osmotic potential significantly correlated with the Na+ content. These results indicated that the presence of a moderate amount of Na+ in the soil could improve the water status of both the soil and the cotton plants, accelerate the absorption and accumulation of Na+ in the roots, lower the tissue osmotic potential, thereby enhancing the suction force of water in plant for maintaining a high cell turgor to maintain a relatively higher photosynthetic rate and growth rate. In this sense, it was suggested that the existence of a certain amount of NaCl in soil could effectively alleviate the adverse effects of drought on cotton.
    Effects of chlorophylliniron on osmotic adjustment and activities of antioxidantive enzymes in cucumber seedlings under suboptimal temperature.
    ZHANG Meng1, WANG Xiu-feng1,2, ZHANG Fan-yang1, WEI Min1,2,3, SHI Qing-hua1,2, YANG Feng-juan1,2, LI Yan1
    2014, 25(12):  3527-3532. 
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    Cucumber cultivar ‘Jinyan 4’ was subjected to suboptimal temperature treatment of 18/12 ℃ (day/night) in the growth chambers. A solution culture experiment was conducted to study the effect of exogenously spraying 5 mg·L-1 chlorophylliniron solution on plant growth, the content of proline, soluble sugar, MDA and activity of peroxidase in the leaves of cucumber seedling under suboptimal temperature. Application of chlorophylliniron showed prominent effects on mitigating the stress of suboptimal temperature on growth of the cucumber seedlings, significantly increasing the plant height, leaf area, shoot dry mass, the contents of soluble sugar and proline and the activities of SOD, POD, CAT and APX. Exogenously spraying chlorophylliniron could promote the accumulation of proline and soluble sugar, raise the activities of antioxidant enzymes, decrease the membrane lipid peroxidation and improve the adaptability of cucumber seedlings under suboptimal temperature.

     
    Effects of soil progressive drought during the flowering and boll-forming stage on gas exchange parameters and chlorophyll fluorescence characteristics of the subtending leaf to cotton boll.
    LIU Zhao-wei, ZHANG Pan, WANG Rui, KUAI Jie, LI Lei, WANG You-hua, ZHOU Zhi-guo
    2014, 25(12):  3533-3539. 
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    To investigate the dynamic changes and response mechanisms of gas exchange parameters and fluorescence indices of the subtending leaf to cotton boll under soil progressive drought stress, pot experiments of the hybrid cotton No.3 were conducted with soil relative water content (SRWC) (75±5) % as control group, SRWC (60±5) % and SRWC (45±5) % as experimental groups dealt with progressive drought for 50 days. Results showed that, the net photosynthetic rate (Pn), stomatal conductance (gs) and leaf intercellular CO2 concentration (Ci) decreased while Ls increased under SRWC (60±5) %  for 0-21 days. Furthermore, there was no significant change in chlorophyll fluorescence indices. This indicated that stomatal limitation was the main reason for the reduction of photosynthesis of cotton. In addition, when drought for 21-49 days under SRWC (60±5)%, Pn kept decreasing, while Ci began to increase and Ls began to decrease. Potential photochemical efficiency (Fv/Fm), quantum yield of photo system II (ΦPSII) and photochemical quenching coefficient (qP) reduced significantly, but nonphotochemical quenching coefficient (NPQ) first rose then decreased. Thus, nonstomatal limitation was the main reason why the photosynthesis of cotton reduced. Photosynthetic organization and photosynthetic enzyme system were destroyed, boll setting intensity reduced and the number of boll and yield reduced significantly. Drought for 0-14 days under SRWC (45±5) % treatment led to sharp decrease in Pn, gs and Ci, whereas Ls obviously increased. There was no significant change in Fv/Fm, ΦPSII, qP, indicating stomatal limitation was the main reason why the photosynthesis of cotton reduced. Pn decreased slowly, while Ci began to rise and Ls began to decline under SRWC (45±5) % treatment for 14-49 days. Fv/Fm, ΦPSII, qP  decreased while NPQ rose first then declined, which indicated that non-stomatal limitation worked to reduce the cotton photosynthetic performance. The boll setting intensity reduced significantly and the number of boll and yield declined. The critical stress time of cotton growth in current study was 21 and 14 days respectively under SRWC (60±5) % and SRWC (45±5) % treatments during the flowering and boll-forming stage.
    Regulation of different calcium forms on the photosynthesis of tomato leaves under heat stress.
    QI Hong-yan1, WANG Dan1, QI Ming-fang1, LIU Yu-feng1, HE Yu2, LI Tian-lai1
    2014, 25(12):  3540-3546. 
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    The regulation of different calcium forms, namely CaCl2, Nano-calcium and Manntiol-calcuim, on the gas exchange and fluorescence of tomato leaves under heat stress was investigated. The results showed that all forms of calcium  alleviated the decrease of chlorophyll a and carotenoid contents in leaves of tomato seedlings under heat stress, enhanced the net photosynthesis rate (Pn), transpiration rate (Tr) and stomatal conductance (gs) to varying degrees, reduced the quantum yield of non-regulated energy dissipation \[Y(NO)\] of PSII and quantum yield of non-photochemical energy dissipation in PSI due to acceptor side limitation \[Y(NA)\], promoted the regulated energy dissipation \[Y(NPQ)\] and quantum yield of non-photochemical energy dissipation in PSI due to donor side limitation \[Y(ND)\], and increased the calcium content in leaves. Generally, manntiol-calcium and nano-calcium were more effective than CaCl2, and more suitable to enhance the photosynthesis of leaves oftomato seedlings under heat stress.
     
    Effects of nitrogen forms on the growth, yield and fruit quality of tomato under controlled alternate partial root zone irrigation.
    ZHANG Qiang1, XU Fei1,2, WANG Rong-fu2, SHU Liang-zuo1, LIU Rui1, ZHANG De-yu1
    2014, 25(12):  3547-3555. 
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    The effects of nitrogen (N) forms (ammonium-N and nitrate-N) on the growth, yield and fruit quality of tomato plants (cv. Zhongyan 988) under controlled alternate partial root zone irrigation (APRI) were examined in a splitroot experiment. Under the same irrigation mode and/or controlled soil water limitation treatment, ammoniumN promoted plant growth at the early stage, while nitrate-N improved plant growth and development at the later stage leading to higher biomass accumulation and fruit yield at harvest. Under APRI and the same soil water conditions, plants of the nitrate-N treatment improved the content of vitamin C and the ratio of soluble sugar to organic acid and thus facilitated fruit quality when compared with those of the ammonium-N treatment. Plant height and leaf area under APRI treatment were lower compared with conventional irrigation (CK) under the same N form, but the stem diameter under APRI treatment with 60% θf 〖KG*2〗(field water capacity, θf) soil moisture showed a slight increase at the late growth stage. Under the same N form, fruit yield was significantly lower in APRI treatment than that of the CK. Compared with the CK, fruit yield decreased by 22.4%-26.3% under the APRI treatment with 40%θf soil moisture. Under 60%θf soil moisture, the APRI treatment significantly improved fruit quality and wateruse efficiency compared with the CK regardless small reduction (5.3%-5.4%) in fruit yield. The experimental results suggested that the APRI treatment with the lower limitation of soil moisture controlled at 60%θf and nitrateN supply would be the optimal option in terms of sustainable use of water resource and fertilizer.
     
    Effects of different catch modes on soil enzyme activities and bacterial community in the rhizosphere of cucumber.
    LI Min, WU Feng-zhi
    2014, 25(12):  3556-3562. 
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    Effects of different catch modes on soil enzyme activities and bacterial community in the rhizosphere of cucumber (Cucumis sativus) were analyzed by conventional chemical method, PCR-denaturing gradient gel electrophoresis (DGGE) and realtime PCR methods. Pot experiment was carried out in the greenhouse for three consecutive years with cucumber as the main crop, and scallion (Allium fistulosum), wheat (Triticum aestivum) and oilseed rape (Brassica campestri) as catch crops. Results showed that, with the increase of crop planting times, soil urease, neutral phosphatase and invertase activities in the wheat treatment were significantly higher than in the scallion and oilseed rape treatments, and these enzyme activities in the oilseed rape treatment were significantly higher than in the scallion treatment. PCR-DGGR analysis showed that cucumber rhizosphere bacterial community structures were different among treatments. Scallion and wheat treatments maintained relatively higher diversity indices of bacterial community structure. qPCR results showed that the abundance of soil bacterial community in the wheat treatment was significantly higher than in the scallion and oilseed rape treatments. In conclusion, different catch treatments affected soil enzyme activities and bacteria community and changed the soil environment. Wheat used as summer catch crop could maintain relatively higher soil enzyme activities, bacterial community diversity and abundance.
    Effects of grafting on physiological characteristics of melon (Cucumis melo) seedlings under copper stress.
    TAN Ming-ming1,2, ZHANG Xin-ying1, FU Qiu-shi1, HE Zhong-qun2, WANG Huai-song1
    2014, 25(12):  3563-3572. 
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    The effects of grafting on physiological characters of melon (Cucumis melo) seedlings under copper stress were investigated with Pumpkin Jingxinzhen No.3 as stock and oriental melon IVF09 as scion. The results showed that the physiological characters of melon seedlings were inhibited significantly under copper stress. Compared with selfrooted seedlings, the biomass, the contents of photosynthetic pigment, glucose and fructose, the photosynthetic parameters, the activities of sucrose phosphate synthase, neutral invertase  and acid invertase  in the leaves of the grafted seedlings were increased significantly. The uptake of nutrients was improved with the contents of K, P, Na increased and the content of Cu decreased. When the concentration of Cu2+ stress was 800μmol·L-1, the contents of Cu in the leaves and roots of the grafted seedlings were decreased by 31.3% and 15.2%, respectively. Endogenous hormone balance of seedlings was improved by grafting. In the grafted seedlings, the content of IAA and peroxidase  activity were higher, whereas the contents of ABA, maleicdialdehyde, the activities of superoxide dismutase  and catalase  were lower than that in the control. It was concluded that the copper stress on the physiological characters of melon seedlings was relieved by grafting which improved the resistance of the grafted seedlings.
    Symbiotic matching between soybean cultivar Luhuang No.1 and different rhizobia.
    JI Zhao-jun1,2, WANG Fei-meng2, WANG Su-ge3, YANG Sheng-hui3, GUO Rui3, TANG Ru-you3, CHEN Wen-xin2, CHEN Wen-feng2
    2014, 25(12):  3573-3579. 
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    Soybean plants could establish symbiosis and fix nitrogen with different rhizobial species in the genera of Sinorhizobium and Bradyrhizobium. Studies on the symbiotic matching between soybean cultivars and different rhizobial species are theoretically and practically important for selecting effective strains used to inoculate the plants and improve the soybean production and quality. A total of 27 strains were isolated and purified from a soil sample of Huanghuaihai area by using the soybean cultivar Luhang No.1, a proteinrich cultivar grown in that area, as the trapping plants. These strains were identified as members of Sinorhizobium (18 strains) and Bradyrhizobium (9 strains) based on the sequence analysis of housekeeping gene recA. Two representative strains (Sinorhizobium fredii S6 and Bradyrhizobium sp. S10) were used to inoculate the seeds of Luhang No.1 alone or mixed, in pots filled with vermiculite or soil, and in the field trial to investigate their effects on soybean growth, nodulation, nitrogen fixation activity, yield, contents of protein and oil in seeds. The results demonstrated that strain S6 showed better effects on growthpromotion, yield of seeds and seed quality than strain S10. Thus strain S6 was finally regarded as the effective rhizobium matching to soybean Luhuang No.1, which could be the candidate as a good inoculant for planting the soybean Luhuang No.1 at a large scale in the Huanghuaihai area.
    Influence of fruit size of Camellia meiocarpa on growth of oil tea weevil, Curculio chinensis (Coleoptera: Curculionidae)
    LI Zhi-wen, HE Li-hong, MA Ling, XIA Jiao, ZENG Ai-ping
    2014, 25(12):  3580-3586. 
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    The relationship between mature larval mass of oil tea weevil (Curculio chinensis) and fruit volume of its host plant oil tea (Camellia meiocarpa) was fitted with Logistic equation in order to understand the restriction of host fruit size on large larval growth and development of the weevil. The results showed that the larval mass increased with the increasing host fruit volume, which was in good conformity with the Logistic model. The weevil larval growth followed the principle of diminishing marginal utility, and it could be divided into two periods, the fastgrowing period (<3.216 cm3, one larva per fruit; <4.747 cm3, two larvae per fruit ) and the asymptotic growing period (>3.216 cm3, one larva per fruit; >4.747 cm3, two larvae per fruit). The minimum fruit size threshold was 1.500 cm3 for one larva per fruit, and 2.539 cm3 for two larvae per fruit. The temporal pattern that the mature larvae exited from their host fruits was established, the number of larvae escaping from their host fruits decreased daily after the fruit collection, and the larval escaping peak largely appeared from 6:00 to 10:00 AM with 43.9% of total escaping number, and especially from 7:00 to 8:00 AM with 21.1% of total escaping number. The bigger the larvae, the earlier exited from their host fruits. The restriction of fruit size on growth and development of oil tea weevil was observed, and it should be a behavioral adaptation strategy to increase the offspring’s fitness for the parental weevil adults to oviposit on the bigger fruits.
    Influence of relative humidity on the Adoxophyes orana experimental population.
    SUN Li-na1, SUN Rui-hong2, QIU Gui-sheng1, YAN Wen-tao1, ZHANG Huai-jiang1
    2014, 25(12):  3587-3592. 
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    In order to explore the effects of relative humidity (RH) on the population growth of summer fruit tortrix moth Adoxophyes orana, the development, survival, fecundity and longevity of A. orana were assessed at 6 different constant humidities (40%, 50%, 60%, 70%, 80% and 90%), (25±1) ℃ and a photoperiod of 12L:12D in the laboratory. The results showed that immature developmental time was gradually shortened with the increasing humidity at 40%-90%RH, ranged from 30.31 d at 40%RH to 25.87 d at 90%RH. However, the survival rate for immature moth was gradually increased from 40%RH to 90%RH. Hatchability was inhibited significantly by low humidity and the lowest was 39.3% at 40%RH. And at 80% RH, the longevity of adults was the longest, the oviposition was the most (110.8 eggs per female), and the survival rates for eggs and larvae were the highest. It resulted in the highest net reproductive rate (R0=26.46) and intrinsic rate of increase (rm=0.1018). In conclusion, the development and fecundity of A. orana were promoted and improved at the higher humidity.
     
    Stress effects of imidacloprid on RSV in rice plants.
    WANG Shuang1, FU Hong-wei2, YANG Yi-zhong1
    2014, 25(12):  3593-3599. 
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    The rice stripe disease is a viral disease transmitted by small brown planthopper, Laodelphax striatellus, which outbroke a few years ago in the Yangtze River basin, especially Jiangsu region, China. To study the effects of imidacloprid stress on rice stripe virus (RSV) in rice plants, the rice seedlings were treated with imidacloprid 1, 2, 3 and 4 times (B1, B2, B3 and B4), respectively, after artificial inoculation by L. striatellus for 48 h, and the expression levels of relative genes including RSV NS3, CP, SP and NSvc4, as well as the protein concentrations of CP and SP were detected at different stages by realtime PCR and Western blotting. The results showed that the effects of imidacloprid treatment on the expression levels of four genes were genespecific and correlated with application frequencies of imidacloprid. The expression levels of NS3 gene were upregulated in three treatments, and the highest expression level (10.86) was observed 16 days after inoculation in B4 treatment, but a significant downregulation of NS3 gene was found in all other treatments. The expression levels of CP, SP and NSvc4 genes were downregulated significantly (0-0.74) in almost all B2 and B3 treatments, while a significant upregulation was found in half of B1 and B4 treatments, and the highest expression levels of SP gene were observed 16 days after inoculation in B1 (258.89) and B4 (730.54) treatment, respectively. On the other hand, the effects of imidacloprid stress on the expression patterns of CP and SP genes were different from those of CP and SP proteins. For example, the expression level of CP gene was almost no expression (0) 19 days after inoculation in B1 treatment, while significantly upregulated (23.08)   was observed for CP protein.
    Effects of irrigation of untreated livestock farm wastewater on accumulation and vertical migration of nitrogen and phosphorus in paddy soil.
    ZHANG Ming-kui, AHMED Elgodah, BAO Chen-yan
    2014, 25(12):  3600-3608. 
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    Although a series of process techniques for treating wastewater from livestock and poultry breeding have been developed in China and overseas, it is still common in China’s rural areas for utilization of the untreated wastewater to irrigate farmland directly because of economic reasons. The impact of untreated wastewater irrigation on accumulation and vertical migration of nitrogen and phosphorus in paddy soil is concerned. Consequently, four representative paddy fields with different histories of livestock farm wastewater irrigation (0, 4, 7, 13 years) were selected for collecting profile soil samples to study the effects of long-term irrigation of untreated livestock farm wastewater on various forms of nitrogen and phosphorus in the soils at different vertical depths. As compared with control field without any irrigation of wastewater, long-term irrigation of untreated livestock farm wastewater significantly increased the accumulation of N and P in the soils with increasing the irrigation year, and the increment of total P in the soil was greater than that of total N. Total P content in surface soil from fields with 4, 7, and 13 years irrigation was increased by 43.6%, 95.2%, and 148.4%, while total N increased by 7.6%, 16.9%, and 28.4%, respectively. Different forms of soil N were increased in order of NH4+-N, NO3--N > acid hydrolyzable N > non-acid hydrolyzable N, and soil available P changed much more than total P. Long-term irrigation of untreated livestock farm wastewater could promote vertical migration of soil nitrogen and phosphorus, and increase the pollution risk for groundwater.
    Estimating total nitrogen content in reclaimed water based on hyperspectral reflectance information from emergent plants: A case study of Mencheng Lake Wetland Park in Beijing, China.
    LIU Hui1,2,3,4, GONG Zhao-ning1,2,3,4, ZHAO Wen-ji1,2,3,4
    2014, 25(12):  3609-3618. 
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    Hyperspectral reflectance information is a crucial method to detect total nitrogen content in plant leaves, meanwhile, vegetation nitrogen content has a strong relationship with nitrogen in water. Taking Mencheng Lake Wetland Park supplied with reclaimed water as study area, the vegetation hyperspectral data (Phragmites australis and Typha angustifolia), and the content of total nitrogen in water were detected to investigate the feasibility of estimating total nitrogen content in reclaimed water based on hyperspectral reflectance information from emergent plants. We established simple linear regression model, stepwise multiple linear regression model and partial least square regression model based on four hyperspectral indices (spectral indices, normalized difference indices, trilateral parameters, absorption feature parameters), respectively. The accuracy of these models was  coefficient of determination (R2) and root mean square error (RMSE). The results showed that stepwise multiple linear regression model and partial least square regression model predicted more accurately than simple linear regression model, and the accuracy of prediction models based on P. australis reflectance spectra was higher than those on T. angustifolia. Partial least square regression model was the most useful explorative tool for unraveling the relationship between spectral reflectance of P. australis and total nitrogen content in water with R2 of 0.854 and RMSE of 0.647. 500-700 nm was the best band range for detecting water total nitrogen content. The reflectance ratio of green peak and red valley  could be effectively predicted by the absorption feature parameters.
    Temporal-spatial variations of reference evapotranspiration in Anhui Province and the quantification of the causes.
    CAO Wen1,2, DUAN Chun-feng3, YAO Yun1,2, YUE Wei1,2
    2014, 25(12):  3619-3626. 
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    In this paper, daily reference evapotranspiration (ET0) was computed with the recommended FAO-56 PenmanMonteith equation for Anhui Province using data collected 60 weather stations during 1961 to 2010 and its temporalspatial variations were characterized. The determining factors in ET0 trends were inquired into through partial derivative quantification analysis for the study region. Results showed that the mean annual ET0 was 878.58 mm·a-1 over the whole region during the study period. ET0 was the highest in summer and the lowest in winter. The mean annual ET0 decreased from the north to the south and from low altitude regions to high altitude regions. Both sunshine duration and wind speed were the dominant factors contributing to the interannual change of ET0, with less contribution from air temperature or relative humidity. The annual ET0 showed a general decline at a rate of -1.61 mm·a-1 owing to a more negative contribution of sunshine duration and wind speed than a positive contribution of air temperature and relative humidity. ET0 increased insignificantly in spring and decreased slightly in both autumn and winter. However, it decreased significantly at a rate of -1.37 mm·a-1 in summer. The main impacting factor was wind speed in spring, autumn and winter, but it was sunshine duration in summer. Great differences in the determining factors of the mean annual ET0 existed from area to area in Anhui Province. The wind speed was the determining factor for 36.7% of the whole stations distributing in the southern part of the area north to the Huaihe River and the area along the Huaihe River, while the sunshine duration was the determining factor for the other regions.
    Prediction and simulation of urban area expansion in Pearl River Delta Region under the RCPs climate scenarios.
    JIANG Qun-ou1,2,3, DENG Xiang-zheng2,3, KE Xin-li4, ZHAO Chun-hong2,5, ZHANG Wei1
    2014, 25(12):  3627-3636. 
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    The sizes and number of cities in China are increasing rapidly and complicated changes of urban land use system have occurred as the social economy develops rapidly. This study took the urban agglomeration of Pearl River Delta Region as the study area to explore the driving mechanism of dynamic changes of urban area in the urbanization process under the joint influence of natural environment and social economic conditions. Then the CA (cellular automata) model was used to predict and simulate the urban area changes until 2030 under the designed scenarios of planning and RCPs (representative concentration pathways). The results indicated that urbanization was mainly driven by the nonagricultural population growth and socialeconomic development, and the transportation had played a fundamental role in the whole process, while the areas with high elevation or steep slope restricted the urbanization. Besides, the urban area would keep an expanding trend regardless of the scenarios, however, the expanding speed would slow down with different inflection points under different scenarios. The urban expansion speed increased in the sequence of the planning scenario, MESSAGE scenario and AIM scenario, and that under the MESSAGE climate scenario was more consistent with the current urban development trend. In addition, the urban expansion would mainly concentrate in regions with the relatively high urbanization level, e.g., Guangzhou, Dongguan, Foshan, Shenzhen, Zhanjiang and Chaoshan.
    Estimation on value of water and soil conservation of  agricultural ecosystems in Xi’an metropolitan, Northwest China.
    YANG Wen-yan, ZHOU Zhong-xue
    2014, 25(12):  3637-3644. 
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    With the urban eco-environment increasingly deteriorating, the ecosystem services provided by modern urban agriculture are exceedingly significant to maintain and build more suitable environment in a city. Taking Xi’an metropolitan as the study area, based on remote sensing data, DEM data and the economic and social statistics data, the water and soil conservation service of the agricultural ecosystems was valued employing the remote sensing and geographic information system method, covering the reduction values on land waste, soil fertility loss and sediment loss from 2000 to 2011, and analyzed its changes in time and space. The results showed that during the study period, the total value of water and soil conservation service provided by agricultural systems in Xi’an metropolitan was increased by 46.086 and 33.008 billion yuan respectively from period of 2000 to 2005 and from 2005 to 2011. The cultivated land (including grains, vegetables and other farming land), forest (including orchard) and grassland provided higher value on the water and soil conservation service than waters and other land use. Ecosystem service value of water and soil conservation provided by agriculture was gradually decreasing from the southern to the northern in Xi’an metropolitan. There were significantly positive relationship between the ecosystem service value and the vegetation coverage. Forest, orchard and grassland distributed intensively in the southern which had higher vegetation coverage than in northern where covered by more cultivated land, sparse forest and scattered orchard. There were significantly negative correlation between the urbanization level and the value of water and soil conservation. The higher level of urbanization, the lower value there was from builtup area to suburban and to countryside within Xi’an metropolitan.
    Ecological and economic harmony evaluation and spatial evolution of the Hexi Corridor, Northwest China.
    LIU Hai-long1,2, SHI Pei-ji2, LI Sheng-mei2,3, TONG Hua-li2, NIE Xiao-ying2, WEI Wei2
    2014, 25(12):  3645-3654. 
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    The relationship between economic development and environment and the evolution characteristics of spatial pattern in Hexi Corridor of Northwest China were analyzed based on Landsat TM images in 1985, 1995, 2000 and 2011 with twenty counties in Hexi Corridor chosen as the basic research units. The ecological economic harmony during 1985-2011 was estimated according to ESV (ecosystem services value) and EEH (ecological and economic harmony) index with the ecosystem services value estimation methods. The results showed that the land type of the study area dramatically changed during the study period, the grassland decreased badly, and the construction land and cultivated land increased quickly. The ESV showed an overall downward trend, especially in the Shiyang River basin and the middle of Heihe River. The ESV in the Shule River basin  in this period. After 2000, the economic growth speeded up visibly in the study area. The economic development concentrated in the resourcebased cities and regional central cities, and declined from the center of corridor to the both sides. The ecologicaleconomic relation in Hexi Corridor experienced a transformation of “preliminary deterioration  further deterioration  low grade coordination”. The EEH had large changes in the Shiyang River basin and the middle of Heihe River, which experienced a transformation of “conflict  more conflicts  less conflicts”, however, there was little change in Shule River basin. The development mode and the comprehensive reclamation of Shiyang River basin and Heihe River basin had a significant influence on the regional
     ecological and economic harmony. 
     
    Distribution of macroalgal community and environmental effects in Yangma Island, Yantai, Shandong Province, China.
    HAN Qiu-ying1, YIN Xiang-bo2, LIU Dong-yan1
    2014, 25(12):  3655-3663. 
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    Distribution of macroalgal community was investigated monthly in the intertidal zone of Yangma Island, Yantai, Shandong Province, China during April 2010 to March 2011. Macroalgae sampling was conducted at two sites (A and B) along Yangma Island coastline. The relationships between macroalgae species composition and biomass and environment variables were studied. In total, 35 macroalgae species were identified, including 24 Rhodophyta (68.6% of the total number), 6 Chlorophyta (17.1% of the total number) and 5 Phaeophyta (14.3% of the total number). Brown algae and green algae dominated in summer, and red algae and brown algae dominated in other seasons. Sargassum thunbergii was the dominant species all the year. The biomass of macroalgae was higher in summer and lower in winter. The highest biomass of macroalgae was observed in June. The lowest biomass of macroalgae was observed in January at A sampling site and in November at B sampling site with the characters of macroalgae in the temperate seas. Seawater temperature, nutrients and pH could have significant effects on the variations of macroalgae biomass in the Yangma Island intertidal zone.
    Distribution characteristics and source apportionment of dichloro-diphenyl-tricgloroethanes in Zhangjiang River Estuary of Fujian, China.
    LUO Dong-lian
    2014, 25(12):  3664-3672. 
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    The concentration, distribution and transfer of dichloro-diphenyl-tricgloroethanes(DDTs) in the surface layer water, sediments and aquatic organisms from the Zhangjiang River Estuary were investigated using GC-ECD method. The possible sources were assessed based on the distribution and composition characteristics of DDTs together with the investigation results of dicofol. The results showed that the concentration of DDTs in surface layer water ranged from ND (not detected) to 20.1 ng·L-1 with an average of 10.5 ng·L-1 in dry period, from ND to 45.2 ng·L-1 with an average of 28.3 ng·L-1 in wet period, and from ND to 18.8 ng·L-1 with an average of 5.03 ng·L-1 in level period. Concentration of DDTs in surface sediment (dry mass) ranged from 1.87 ng·g-1 to 144 ng·g-1 with an average of 17.3 ng·g-1, and that in 11 species of aquatic organisms ranged from 1.09 ng·g-1 to 432 ng·g-1 with an average of 37.0 ng·g-1. Compared to other areas, the residues of DDTs in the Zhangjiang River Estuary were at the medium level. The accumulation factors of DDTs in sediment and aquatic organisms were 1185 and 2534, respectively. The capacities for DDTs accumulation were in the order of fish>shellfish>shrimp>aquatic plants. The concentrations of DDTs showed downtrend along the Zhangjiang River, indicating that the residues of DDTs mainly came from terrigenous pollution rather than from the release of antifouling agent of ships. Based on the composition profile, DDTs mainly came from the early residues. However, the highest value of dicofol was recently detected both in the water and sediment of Y-8 station, which suggested that new DDTs inputs at the Y-8 station might be related to the recent usage of dicofol.
    Research progress on phosphorus budgets and regulations in reservoirs.
    SHEN Xiao, LI Xu-yong, ZHANG Wang-shou
    2014, 25(12):  3673-3682. 
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    Phosphorus is an important limiting factor of water eutrophication. A clear understanding of its budget and regulated method is fundamental for reservoir ecological health. In order to promote systematic research further and improve phosphorus regulation system, the budget balance of reservoir phosphorus and its influencing factors were concluded, as well as conventional regulation and control measures. In general, the main phosphorus sources of reservoirs include upstream input, overland runoff, industrial and domestic wastewater, aquaculture, atmospheric deposition and sediment release. Upstream input is the largest phosphorus source among them. The principal output path of phosphorus is the flood discharge, the emission load of which is mainly influenced by drainage patterns. In addition, biological harvest also can export a fraction of phosphorus. There are some factors affecting the reservoir phosphorus balance, including reservoirs’ function, hydrological conditions, physical and chemical properties of water, etc. Therefore, the phosphorus budgets of different reservoirs vary greatly, according to different seasons and regions. In order to reduce the phosphorus loading in reservoirs, some methods are carried out, including constructed wetlands, prefix reservoir, sediment dredging, biomanipulation, etc. Different methods need to be chosen and combined according to different reservoirs’ characteristics and water quality management goals. Thus, in the future research, it is reasonable to highlight reservoir ecological characteristics and proceed to a complete and systematic analysis of the inherent complexity of phosphorus budget and its impact factors for the reservoirs’ management. Besides, the interaction between phosphorus budget and other nutrients in reservoirs also needs to be conducted. It is fundamental to reduce the reservoirs’ phosphorus loading to establish a scientific and improved management system based on those researches.
     
    Research progress on remote sensing of ecological and environmental changes in the Three Gorges Reservoir area, China.
    TENG Ming-jun1, ZENG Li-xiong1, XIAO Wen-fa1, ZHOU Zhi-xiang2, HUANG Zhi-lin1, WANG Peng-cheng2, DIAN Yuan-yong2
    2014, 25(12):  3683-3693. 
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    The Three Gorges Reservoir area (TGR area), one of the most sensitive ecological zones in China, has dramatically changes in ecosystem configurations and services driven by the Three Gorges Engineering Project and its related human activities. Thus, understanding the dynamics of ecosystem configurations, ecological processes and ecosystem services is an attractive and critical issue to promote regional ecological security of the TGR area. The remote sensing of environment is a promising approach to the target and is thus increasingly applied to and ecosystem dynamics of the TGR area on mid and macroscales. However, current researches often showed controversial results in ecological and environmental changes in the TGR area due to the differences in remote sensing data, scale, and landuse/cover classification. Due to the complexity of ecological configurations and human activities, challenges still exist in the remotesensing based research of ecological and environmental changes in the TGR area. The purpose of this review was to summarize the research advances in remote sensing of ecological and environmental changes in the TGR area. The status, challenges and trends of ecological and environmental remotesensing in the TGR area were further discussed and concluded in the aspect of landuse/landcover, vegetation dynamics, soil and water security, ecosystem services, ecosystem health and its management. The further researches on the remote sensing of ecological and environmental changes were proposed to improve the ecosystem management of the TGR area.
     
    Research advances in methyl bromide in the ocean.
    DU Hui-na1, XIE Wen-xia1, CUI Yu-qian1, CHEN Jian-lei1, YE Si-yuan2
    2014, 25(12):  3694-3700. 
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    Methyl bromide is an important atmospheric trace gas, which plays significant roles in the global warming and atmospheric chemistry. The ocean plays important and complex roles in the global biogeochemical cycles of methyl bromide,  not only the source of atmospheric methyl bromide, but also the sink. Therefore, developing the chemical research of the soluble methyl bromide in the ocean, will not only have a certain guiding significance to the atmospheric ozone layer protection, but also provide a theoretical basis for estimating methyl bromide’s contribution to the global environmental change on global scale. This paper reviewed the research advances  on methyl bromide in the ocean, from the aspects of the biogeochemical cycle of methyl bromide in the ocean, the analysis and determination method, the concentration distribution, the seatoair flux and its sources and sinks in the atmosphere. Some deficiencies in the current studies were put forward, and the directions of the future studies were prospected.
    Causes of jellyfish blooms and their influence on marine environment.
    QU Chang-feng1,2, SONG Jin-ming1, LI Ning1
    2014, 25(12):  3701-3712. 
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    Jellyfish blooms have damaged the normal composition and function of marine ecosystem and ecological environments, which have been one of the new marine ecological disasters. In this study, we summarized the possible inducements of jellyfish blooms, and the influences of jellyfish blooms on biogenic elements, dissolved oxygen, seawater acidity and biological community were discussed emphatically. The results showed that jellyfish blooms had a close contact with its physiological structure and life history, which had favorable characteristics including simple body structure, rapid growth, thriving reproduction and short generation interval to tolerate harsh environment better. Jellyfish abundance increased rapidly when it encountered suitable conditions. The temperature variations of seawater might be the major inducing factor which could result in jellyfish blooms. Jellyfish blooms may benefit from warmer temperature that could increase the food availability of jellyfish and promote jellyfish reproduction, especially for warm temperate jellyfish species. Eutrophication, climate change, overfishing, alien invasions and habitat modification were all possible important contributory factors of jellyfish blooms. Jellyfish could significantly influence the form distribution and biogeochemical cycling of biogenic elements. Jellyfish excreted NH4+ and PO43- at a rate of 59.1-91.5 μmol N·kg-1·h-1 and 1.1-1.8 μmol P·kg-1·h-1, which could meet about 8%-10% and 21.6% of the phytoplankton primary production requirement of N and P, respectively. Live jellyfish released dissolved organic carbon (DOC) at a rate of 1.0 μmol C·g-1·d-1. As jellyfish decomposing, the effluxes of total N and total P were 4000 μmol N·kg-1·d-1 and 120 μmol P·kg-1·d-1, respectively, while the efflux of DOC reached 30 μmol C·g-1·d-1. Jellyfish decomposition could cause seawater acidification and lowered level of dissolved oxygen and finally made the ambient water become acidic and hypoxic. The pH decreased by 1.3, while the mean dissolved oxygen demand reached 32.8 μmol·kg-1·h-1. Jellyfish blooms also influenced the marine organism community, which might reduce the biomass of some fish and zooplankton, increase the amount of bacterioplankton, indirectly increase the quantity of phytoplankton and lead to abnormal primary production.