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    10 July 2016, Volume 35 Issue 7
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    Newly discovered seagrass bed and its ecological characteristics in the coastal area of Caofeidian, Bohai Sea.
    LIU Hui1, HUANG Xiao-ping2*, WANG Yuan-lei3, LIANG Zhou-rui1, GU Bin1, SU Ji-lan4
    2016, 35(7):  1677-1683. 
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    A field study was conducted in the coastal area of Caofeidian, Bohai Sea in October 2015. A broad seagrass bed covering approximately 10 km2 was discovered in the northwestern area of Longdao Island. It is the largest seagrass bed discovered so far in Bohai Sea and Yellow Sea, China, with Zostera marina as the dominant species. Z. marina on the shoal showed patchy distribution, with coverage of 2.8±1.1% and shoot density ranging between 28.21±6.35-101.33±17.99 shoots·m-2.The number of leaves per plant, canopy height, rhizome length and root length ranged between 2.00±0.00-4.70±0.64, 15.20±5.84-62.10±7.34 cm, 2.67±1.70-22.20±3.92 cm and 3.67±2.36-8.00±1.90 cm, respectively. The average seagrass biomass was 100.48±47.16 g DW·m-2, and the total biomass was estimated to be 1.0×106 kg (dry weight). A great diversity of nekton and benthic animals was observed during this survey, including a large quantity of juvenile and young fish and molluscs, as well as adult fish and shellfish species. However, the co-verage and shoot density of the seagrass were relatively low, and the number of branches and leaves per plant were also relatively few, which indicated a trend of serious decline in the seagrass bed, possibly attributing to seasonal changes as well as excessive anthropogenic activities. This is the first report on the species identification, distribution and ecological characteristics of seagrass in the Caofeidian area, providing an important basis to initiate further study for protecting the seagrass ecosystem in this region.
     
    Spatial and temporal distribution of novel species in China.
    2016, 35(7):  1684-1690. 
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    This research collected the scientific papers concerning on novel species in China from the Web of Science Database, the China Knowledge Resource Integrated Database and the VIP Journal Integration Platform using the bibliometric method. The publication date, classification and location data of novel species were extracted to explain the spatial and temporal distribution pattern in China. The results showed that from 1958 to 2014, a total of 3707 novel species were reported, belonging to Kingdoms of Bacteria, Cyanobacteria, Fungi, Plantae and Animalia. Among the five kingdoms, the number of novel species in Class Insecta, Phylum Arthropoda, Animalia was the largest and occupied 48% of the total novel species. The temporal distribution pattern displayed an increasing trend over the research period and 6 peaks were observed, especially in 2012, the number of novel species reached 369. The spatial distribution pattern analysis suggested that except the Bacteria and Cyanobacteria, the other three kingdoms in Southwest China had the greatest number of novel species. In addition, the spatial distribution patterns of novel species in Plantae and Animalia were closely related.
    Geographical distribution pattern of endemic bryophytes in China.
    GAO Jie, ZHANG Xing, ZHANG Peng, LIU Yan-hong*
    2016, 35(7):  1691-1696. 
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    Currently, endemic plants’ geographical distribution pattern and formation mechanism are the main research content of ecology. In this paper, data of endemic bryophytes information, spatial factors, weather factors, habitat heterogeneity factors from 28 provinces in China were used for analysis. We eliminated the spatial autocorrelation of the spatial data and adopted regression analysis and variance decomposition to analyze the relationships between ecological factors and the richness of endemic mosses (MRN), liverworts (LRN) and bryophytes (BRN). We analyzed the degree of interpretation of space model, environmental model and habitat heterogeneity model to the distribution pattern of MRN, LRN and BEN. The results showed that: (1) Chinese bryophytes’ richness distribution pattern showed significant regional differences, with higher richness in areas with great elevation gradient, such as QinghaiTibet and YunnanGuizhou Plateau. LRN and MRN were the highest in Yunnan, reaching up to 146 and 79, with lower richness in areas with small elevation gradient and less rainfall. Spatial location and topography influence the formation of endemic species. (2) MRN, LRN and BRN had strong spatial variability and their variation tendency was similar: at small scales (<600 km), MRN, LRN and BRN showed obvious positive correlation, however, when the scale reached about 2800 km, they showed maximum negative correlation and were characterized by significant latitudinal gradient; (3) MRN’s geographical distribution pattern mainly depended on habitat heterogeneity (complex terrain conditions) and spatial factors. At large spatial scale, location determined the theoretical value of MRN of a given area, while habitat heterogeneity and climate factors adjusted the MRN slightly. However, the geographical distribution patterns of LRN and BRN were mainly affected by climate and habitat heterogeneity.
    Predicting the potential invasive distribution and earlywarning monitoring management of Solanum elaeagnifolium in China.
    WANG Ru1, WAN Fang-hao1,2*
    2016, 35(7):  1697-1703. 
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    Solanum elaeagnifolium is a worldwide notorious weed and has been declared a harmful quarantine weed in China. Since its first recorded occurrence in China in 2012, the proliferation of this weed has rapidly increased. To monitor and control further introduction of this pest and effectively impede its secondary spread, it is necessary to establish earlywarning monitoring program by accessing the risks of its introduction and by predicting its potential dissemination in China. The introduction of S. elaeagnifolium from North America to Africa, Asia, Australia, Europe and South America indicated that commodity imports or human activities originating in North America were the sources of the seeds of this plant, which led to its invasion and global spread. The potential distribution was predicted by application of Maxent ecological niche model on the basis of its global known occurrences. Following evaluation of the model’s accuracy, its high predictability was selected and projected onto the landscape of China. With the exception of three provinces of northeast China (Heilongjiang, Liaoning and Jilin), Inner Mongolia, Qinghai, northern parts of Xinjiang and Hebei, most areas in China were found to foster the survival of S. elaeagnifolium. Because of its high reproductive capability, as well as its diverse invasion and dispersal mechanisms and the huge area for potential distribution, this species may invade additional locales areas and spread faster in the future. To prevent further invasion and spread of S. elaeagnifolium, it is recommended that an eradication program should be adopted in the newly invaded areas. In addition, monitoring programs should be applied in potentially vulnerable regions, particularly in coastal harbors, airports, transfer stations and processing factories of imported cereal grains or fodder crops, which are highly vulnerable to contamination by S. elaeagnifolium.
    Biomass and annual growth of different aged rubber plantations mixed with Rauvolfia vomitoria and Flemingia macrophylla in Xishuangbanna.
    ZHANG Sen1,2, XIE Zhi-yin3, CHEN Lei-xi4, LIU Cheng-gang2, ZHAO Yong-xiang3, WANG Xiu-hua3, LIU Chang-an2, TANG Jian-wei2*
    2016, 35(7):  1704-1712. 
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    Mixedspecies forest plantations have been established in a large area in the tropics of China, playing an important role in carbon sequestration. To understand the changes in annual growth and biomass allocation, we investigated height (H), diameter at breast height (D) and basal diameter (BD) from different aged rubber plantations (8-, 11- and 20-year-old) mixed with Rauvolfia vomitoria and Flemingia macrophylla (RM) and adjacent pure rubber plantations (CK) in Xishuangbanna, in December 2013 and 2014. Also, the biomass regression models were established. The annual growth in D or BD and biomass increment of different trees in RM decreased with increasing stand age. The D’s annual growth of rubber trees in 8-, 11- and 20-year-old RM was 1.16, 1.01 and 1.17 times of that in CK, with annual biomass increment being 1.13, 1.08 and 1.49 times, respectively. The total biomass was 111.16, 112.53 and 119.53 t·hm-2 in the 8-, 11- and 20-year-old RM, respectively, being 1.35, 0.60 and 0.17 times higher than that in CK. However, the total biomass increment decreased with stand age, ranging from 53.20 t·hm-2 in 8-year-old RM, 33.64 t·hm-2 in 11yearold RM to 11.18 t·hm-2 in 20-year-old RM, which were 5.13, 4.48 and 2.63 times of that in CK respectively. The relative contributions of stems and branches to total biomass increased with stand age in both RM and CK, while the contributions of leaves and roots decreased. The results suggest that biomass accumulation will be greatly enhanced by constructing mixed-species rubber plantation.
    Physiological adaptation mechanism of different aged leaves of Trifolium repens L. to different seasonal temperatures.
    ZHANG Yue1, ZHOU Rui-lian1, LIANG Hui-min2*, ZHANG Ting-feng1
    2016, 35(7):  1713-1720. 
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    In this study, the activities of superoxide dismutase (SOD), peroxide (POD) and catalse (CAT), and the contents of soluble sugar, soluble protein, proline, malondialdehyde and chlorophyll in different aged leaves (young, middleaged, old) of white clover (Trifolium repens) were investigated in different seasons to understand how different aged leaves of white clover adapt to different seasonal temperatures in physiology and what ecological role of leaf senescence plays in maintaining stolon growth. The result showed that: (1) young leaves grown in winter had lower MDA content, and higher values in chlorophyll a content, SOD and POD activities, and soluble sugar and proline contents. However, young leaves grown in summer had higher MDA and chlorophyll b contents, but had lower SOD and POD activities and soluble sugar and proline contents. It is indicated that young leaves had higher physiological regulation plasticity in adaptation to different seasonal temperatures. (2) There existed a similar model of physiological regulation in the developing leaves grown in different seasons. When young leaves became mature, the contents of chlorophyll and soluble sugar and proline, and the activities of SOD and POD increased, while MDA content decreased. (3) Aging leaves grown in different seasons had same physiological characteristics. With the leaves becoming senescent, the soluble sugar and proline contents still increased, but the activities of SOD and CAT and content of MDA decreased. The antioxidant enzyme system and osmoregulation played an important role in physiological protection of young leaves to adapt different seasonal temperatures and in keeping their rapid growth by maintaining metabolic balance of oxygen free radicals and water metabolic balance. During leaf development, the antioxidant capacity decreased, and the proline and soluble sugar kept on accumulation, which was the reason inducing leaf senescence and short life. However, short life of leaves grown in different seasons would make more energy and matter being allocated to stolon top and promote leaf initiation, stolon elongation growth, and population expansion, which played an important physiological regulating role in maintaining growth of white clover in different seasons.
    Effects of cutting on photosynthetic and chlorophyll fluorescence parameters of Medicago sativa under enhanced UV-B radiation.
    WANG Wei1, WANG Yan1, ZHAO Tian-hong1*, LIANG Bian-bian2, GUO Shu-yuan1, TIAN Rong-rong1
    2016, 35(7):  1721-1729. 
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    This paper investigated the photosynthetic fluorescence properties and aboveground biomass of currentyear Medicago sativa (Golden Empress) in response to enhanced UVB radiation by 5% (T1) and 10% (T2) under severe cutting. The results indicated that, with the increase of UV-B radiation, all the experimental indicators declined significantly compared with those of CK in each growth stage. After cutting, the contents of Chla, Chlb and Chl(a+b), net photosynthetic rate and fluorescence parameter Fv/Fm of M. sativa increased significantly at the low dose of UV-B radiation (T1) in the branching stage and podding stage. At the high dose of UV-B radiation (T2), cutting significantly enhanced those five indicators by 32%, 30%, 20%, 17% and 22% respectively in the branching period and podding period. The aboveground biomass after severe cutting increased by 49% and 199% after T1 and T2 treatments, respectively. The cutting and the enhanced UV-B radiation did not show significant interaction on photosynthesis and fluorescence of M. sativa. So it was concluded that moderate cutting can alleviate the damage of UV-B radiation on M. sativa to a certain extent.
    Effects of multi-year milk vetch application on weed seedbank density and biodiversity in paddy field.
    TANG Shan1, WANG Yun-qing1*, ZHANG Zhi2, WU Li-meng2, HUANG Jun3, CAO Wei-dong4
    2016, 35(7):  1730-1736. 
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    Based on a 7-year sitespecific experiment, we studied the density and biodiversity of weed seedbank with milk vetch application in paddy field, discussed the relationship between weed seed community and soil fertility factors. The results showed that yearly milk vetch application significantly reduced the density of paddy weed seedbank and main weed seed species, such as Lapsana apogonoides, Juncellus serotinus (P<0.05). In 0-20 cm soil layer, Shannon index, Simpson index and Pielou index of weed seed were in order of chemical fertilizer with milk vetch application treatment, chemical fertilizer without milk vetch application treatment, no fertilizer treatment in descending order. Yearly milk vetch application significantly improved richness and evenness of weed seedbank (P<0.05). Yearly milk vetch and fertilizer application had a significant effect on major soil fertility factors (P<0.05). The soil pH had a significant negative correlation with biodiversity index of weed seedbank (P<0.05). The increase of soil total N and available N highly significantly improved the weed seedbank biodiversity (P<0.01). There was also a positive relationship between weed seedbank biodiversity and soil available N (P<0.1).
    Enhanced low-temperature resistance and physiological mechanism of maize seedlings by exogenous application of 5-aminolevulinic acid.
    SUN Yang, WANG Yi, QU Dan-yang, LI Jing, JIAO Jian, CAO Xin-bo, GU Wan-rong, WEI Shi*
    2016, 35(7):  1737-1743. 
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    Low temperature is one of the major factors which produce adverse effects on maize growth and development in Northeast China. 5-aminolevulinic acid (ALA) can improve the low temperature resistance of crops. The objective of this study was to investigate the physiological mechanism of ALAenhanced lowtemperature resistance in maize seedlings as well as the optimal foliar spraying concentration of ALA. This experiment was conducted with maize cultivar ‘Suiyu 13’ under different concentrations of ALA (0, 10, 20, 30, 40 mg·L-1), at low temperature of 14 ℃/5 ℃ (day/night) for 48 h. Plant morphological growth, cell membrane stability, antioxidant enzyme activity and osmotic adjustment ability were measured. The results showed that foliar spraying of ALA could promote the growth of seedlings under low temperature stress, protect the structure and function of leaf cell membrane, enhance the ability of the cell to remove reactive oxygen species and improve the ability of osmotic adjustment. Among all treatment concentrations, 20 mg·L-1 ALA spraying treatment had the best effects. Compared with the control, seedling height, leaf area and fresh (dry) weight increased by 24%, 23%, 26% (23%), the malondialdehyde (MDA) content and relative electrical conductivity decreased by 38% and 45%, SOD activity and POD activity increased by 37% and 66%, soluble protein content and soluble sugar content increased by 50% and 45%, respectively, under the treatment of 20 mg·L-1 ALA. Therefore, spraying ALA of appropriate concentration can relieve the damage caused by low temperature stress to maize seedlings.
     
    Intraspecific and interspecific competition intensity of Parrotia subaequalis in different habi-tats from Wanfoshan Nature Reserve, Anhui Province.
    ZHANG Guang-fu1*, YAO Rui1, JIANG Yue-qian2, CHEN Fu-cheng2, ZHANG Wen-yan2
    2016, 35(7):  1744-1750. 
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    The intraspecific and interspecific competition intensities of rare and endangered tree Parrotia subaequalis in Wanfoshan Nature Reserve, Anhui Province, were quantitatively analyzed with Hegyi singletree competition index model. Meanwhile, for the same tree species from a certain forest community, its competition intensity in two different habitats (hillside and valley) was also discussed. The results showed that the main competitive intensity of the P. subaequalis population came from interspecific competition, and the value was 240.6, which accounted for 69.3% of the total. The competition intensity of intraspecific and interspecific competition with P. subaequalis followed the order of P. subaequalis> Celtis biondii> Cyclobalanopsis glauca> Pistacia chinensis> Celtis sinensis> Liquidambar formosana> Machilus leptophylla. Notably, individual number of P. subaequalis and intensity of intraspecific and interspecific competition were different between the two habitats. The number of trees of P. subaequalis in hillside (178) was more than that in valley (only 65); both intraspecific and interspecific competition intensity in hillside was stronger than in valley. The competition intensity of this species in the small size class (4.0 cm≤DBH＜8.0 cm) was the strongest both in hillside and in valley. There was a significant negative correlation between the whole forest competition intensity and the DBH of objective trees (CI=ADB). The competition intensity of P. subaequalis declined with increasing DBH, and the stress was more intense for trees with DBH less than 16 cm. In addition, it is suggested that the competition intensity in different habitats may be probably different for a certain tree species in forest communities.
    Comparison and optimal fitting on standing aboveground crop of Stipa breviflora desert steppe under different grazing intensities.
    LV Shi-jie1, LIU Wen-ting2, LIU Hong-mei3, SUN Shi-xian2,4, WEI Yuan2,4, ZHANG Shuang2, WEI Zhi-jun2*
    2016, 35(7):  1751-1760. 
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    To discuss the variation of aboveground standing biomass of desert steppe under seasonal regulation of grazing intensity and the relationship between grazing intensity and seasonal regulation, we collected the observational data of the aboveground standing biomass in Stipa breviflora desert steppe of the Mongolian Plateau in September 2010-2014, and analyzed the standing aboveground biomass in the desert steppe using comparative analysis and regression modeling. The results showed that there were significant differences in both experimental treatments and years on the aboveground standing biomass in the desert steppe (P<0.01), and the grazing treatment effect was greater than the interannual biomass change caused by the variations of annual precipitation and air temperature. Regression modeling analysis showed that a general model could be used to predict the aboveground standing biomass changes of 27 experimental treatments and its fitting rate was more than 99% by 6 experimental treatments. The model also showed that the increased grazing intensity in spring could lead to decreased grassland utilization, and the grazing intensity of previous season can significantly affect the grazing of subsequent season. Different grazing seasons had additive effects, which led to an amplified influence of the previous grazing in the subsequent grazing season, and thus reduced the recoverability of grassland after heavy grazing.
    Impacts of film mulch planting on NDVI identification in corn early growth.
    MENG Qing-lan, GAO Jun-kai, LU Xiao-qian, CHANG Xue-li*
    2016, 35(7):  1761-1766. 
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    Film mulch planting is commonly adopted in oasis agriculture in arid zone, and largescale film mulch cultivation may have significant effects on the remote sensing monitoring for NDVI of crop’s early growth. In order to better understand spectral reflectance characteristics of different mulch materials, this study employed black film and transparent film, compared with bare cropland, to illustrate the impact of film mulch planting on NDVI identification in corn’s early growth. The results showed that the spectral reflectance among black film, transparent film and bare cropland existed significant difference (P<0.05). At 325-1035 nm wavelength, the average spectral reflectance of transparent film, bare cropland and black film were 25.9%, 13.9% and 13.7%, respectively. For Landsat and MODIS data, relationship between the mulching area and NDVI was linear in largescale film mulch cultivation area, and the slope of the regression equation of the transparent film was larger than that of the black film. These results indicated that the mulch film planting had significant influence on identifying the corn’s early growth based on NDVI monitoring.
    Relationships between the genetic diversity of Pinus yunnanensis Franch. natural populations and ecological factors.
    XU Yu-lan1*, CAI Nian-hui1, CHEN Shi1, WANG Da-wei1, HE Cheng-zhong1, DUAN An-an1, KANG Xiang-yang2
    2016, 35(7):  1767-1775. 
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    The genetic diversity and genetic differentiation of 20 Pinus yunnanensis Franch. natural populations collected from the main distribution areas were studied by Simple Sequence Repeat (SSR) marker. The relationships among the genetic diversity and the main ecological factors, i.e., geographical, climatic and soil parameters, were analyzed. The genetic diversity parameters based on SSR loci for 20 natural populations were correlated with geographical, climatic and soil parameters. Those populations with rich genetic diversity existed in low latitude, low altitude, warm and moist environment. There was no significant relationship between matrices of genetic distance and matrices of geographical distance by Mantel test, which indicated that there was no evident sign of geographical isolation. But the ecological isolation was more obvious than geographical isolation. The genetic differentiation among populations may be influenced by geographical, climatic or soil factors. Climate factor had a main influence on genetic diversity of P. yunnanensis.
    Precipitation characteristics in alpine grassland in the upper reaches of Shule River during growing season.
    LI Qing-feng1,2,3, YANG Guo-jing2*, ZHAO Chuan-cheng2
    2016, 35(7):  1776-1782. 
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    Based on field observation data from alpine region (3400-4200 m) in the upper reaches of Shule River between 2009 and 2014, the precipitation characteristics in alpine grassland during growing season (May-September) were evaluated by the methods of anomaly percentage, precipitation concentration degree (PCD) and precipitation concentration period (PCP) in this paper. The results showed that precipitation during growing season was between 139.3 and 401.6 mm, with the anomaly percentage generally ranging from -12.9% to 18.8%, and the precipitation gradient up to 21.7 mm·100 m-1 (2013-2014). The maximum monthly precipitation was mainly concentrated in July or June, and their sum amounted to 55.7%-60.1% of growing season precipitation. The PCD ranged from 0.21 to 0.49 and the PCP occurred in the late June to July. The majority of single precipitation events were characterized by magnitude <10 mm, duration <24 h, intensity <0.5 mm·h-1. Growing season precipitation in alpine grassland in the upper reaches of Shule River had the characteristics of small interannual variability, obvious vertical variation as well as uneven distribution, and was composed mainly of smallprecipitation events.
    Effects of plant diversity on methane emission in microcosms of constructed wetlands.
    ZHAO Zheng-yan1, ZHONG Yu-chen1, HAN Wen-juan1, TANG Yu-li2, FAN Li-kun2, FAN Xing1, CHANG Jie1, GE Ying1*
    2016, 35(7):  1783-1790. 
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    In order to study the mitigation possibility of methane (CH4) emission in constructed wetlands for waste water treatment, a controlled microcosm experiment was conducted. The effects of plant species richness and identity on CH4 emission, nitrogen removal and related parameters were analyzed. Three hygrophilous plants (Rumex japonicus, Oenanthe javanica and Phalaris arundinacea) were applied to establish the monocultures of three individual species and a 3species mixture. The microcosms were filled with fine sand (particle diameter 0.25-1 mm) and supplied with simulated wastewater. The results showed that plant species richness increased CH4 emission (P<0.05), but had no excessive emission effect (P>0.05). Species richness had no significant effect on nitrogen removal (P>0.05). Plant species identity surpassed species richness as a key driver of CH4 emission and nitrogen removal. Microcosms with P. arundinacea monoculture had the lowest CH4 emission and the highest nitrogen removal (P<0.05). These results suggested that assembling P. arundinacea monoculture is more conducive to reduce CH4 emission and enhance nitrogen removal in constructed wetland simultaneously than improving species richness. This study can provide a reference for plant species selection and plant diversity assemblage in constructed wetlands.
    Assessment on climatic potential productivity of tea in Zhejiang Province.
    JIN Zhi-feng1*, YANG Dong2, YAO Yi-ping1, LI Ren-zhong1, WANG Zhi-hai1
    2016, 35(7):  1791-1798. 
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    Based on the meteorological data observed by 65 basic weather stations and statistical data of tea yield, the photosynthesis potential productivity (YQ), photothermal potential productivity (YT), and climatic potential productivity (YW) of tea in Zhejiang Province in the past 43 years were evaluated with successive correction analysis. The main factors influencing YW were explored by analyzing the spatial and temporal variation of potential productivity. The climate resource utilization (P) was also assessed by combining the YW with actual productivity (Ya). The results showed that,  in the past 40 years, the YQ of tea in Zhejiang Province was 15.17 t·hm-2, with high value in north region and low value in the south region. The YT of tea was 11.27 t·hm-2, increasing gradually from Jinhua to the surrounding areas. The YW of tea was 8.39 t·hm-2, decreasing gradually from south to north. In the past 40 years, YQ, YT and YW all presented a decreased trend, with a climatic trend rate of -0.15, -0.45 and -0.40 t·hm-2·10 a-1, respectively. The variation speeds of YT and YW were more significant than that of YQ as the variation trend of heat and water resources was more obvious than that of solar radiation in the context of climate change. The P of tea in Zhejiang Province was 1.73%-35.12% (with an average of 11.90%) from 2009 to 2013. High P (>20%) was mainly distributed in the east of Hangzhou, Shaoxing, Ningbo, south of Huzhou, and middle of Jinhua.
    Simulation of the responses of soil temperature and soil heterotrophic respiration to climate warming in a subtropical evergreen broadleaved forest.
    LIU Yun-tong1, ZHANG Yi-ping1,2*, WU Chuan-sheng2,4, LIANG Nai-shen3, SHA Li-qing1,2, LUO Xin2, LIU Yu-hong1,2
    2016, 35(7):  1799-1806. 
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    To improve our understanding of the responses of soil temperature and soil heterotrophic respiration to global warming in forest ecosystem, we simulated the change trend of soil temperature of subtropical evergreen broadleaved forest in Ailao Mountains using the observed soil temperature data from 1986 to 2013, and computed the time required for a 2 ℃ increase in soil temperature. We conducted a soil warming experiment in a subtropical evergreen broadleaved forest in Ailao Mountains. We compared field observations from trenching (NR) and trenching with soil warming (SW) from 2011 to 2013 with simulation results obtained from the WNMM model using future climate data under SRES A2 and B2 scenarios. We found that the soil temperature at 5 cm depth was significantly increased by 0.224 ℃·10 a-1 in the last 30 years, and thus it would spend 90 years to increase 2 ℃. The apparent respiration temperature sensitivity index (Q10) was 5.17 and 4.50 under the NR and SW treatments, respectively. Based on the Q10 value, under a 2 ℃ increase in soil temperature, soil heterotrophic respiration under the NR treatment was 14.6% higher than that of the SW treatment. The WNMM model was able to simulate soil water content (P<0.001) and soil temperature (P<0.001) after calibration and validation. By the end of 2100, soil heterotrophic respiration under the NR treatment would be 10.2% and 9.8% higher than that under the SW treatment under SRES A2 and B2 scenarios, respectively, and the soil heterotrophic respiration under the NR and SW treatments would be 7.0% and 6.6% higher under the SRES A2 scenario than under the SRES B2 scenario, respectively. These results indicated that field experiments on soil warming were important for understanding the responses of soil heterotrophic respiration to global warming, and should not be replaced by model simulation in that the latter will overestimate soil heterotrophic respiration.
    Effect of carbon and nitrogen addition on nitrous oxide flux during thawing of frozen temperate forest soils with different moisture levels. 
    WU Hao-hao1,2, XU Xing-kai1*, DUAN Cun-tao1, LI Tuan-sheng3, CHENG Wei-guo4
    2016, 35(7):  1807-1818. 
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    Packed soilcore incubation experiments were done to study the effects of carbon (glucose, 6.4 g C·m-2) and nitrogen (NH4Cl and KNO3, 4.5 g N·m-2) addition on nitrous oxide (N2O) flux during thawing of frozen temperate forest soils with two moisture levels (55% and 80% WFPS, waterfilled pore space) collected from a mature broadleaf and Korean pine mixed forest (BKPF) and adjacent secondary white birch forest (WBF). The results showed that freezing stimulated N2O fluxes from the two forest soils shortly after thawing. With increasing soil moisture, the magnitude and longevity of the flush of N2O fluxes from the two forest soils were enhanced during the early period of thawing, which was accompanied by great NO3--N consumption by denitrification, especially in the WBF soil. The addition of glucose significantly increased N2O fluxes from the two forest soils during the early period of thawing, with great consumption of NH4+-N and NO3--N. With increasing soil moisture, the priming effect of glucose on the N2O flux decreased in the two forest soils, which was probably related to a greater release of dissolved organic carbon (DOC) into the soils with high moisture after thawing. Under low soil moisture conditions, N2O fluxes were subjected to the limitation of NH4+-N pool in the two forest soils during thawing, indicating the relatively great nitrification potential, especially in the WBF soil. However, under high soil moisture conditions, denitrification potential became relatively high in the WBF soil and was enhanced by the addition of glucose. A stepwise regression analysis showed that 66% of the variability in the cumulative N2O emissions from the two forest soils during thawing could be explained by the soil pH, WFPS and waterextractable DOC pool. The cumulative N2O emissions from the two forest soils were significantly and positively correlated to the soil waterextractable dissolved organic nitrogen pool after thawing. The cumulative N2O emission from the BKPF soil was negatively correlated to the soil microbial biomass N. From the experimental results, it can be reasonably concluded that N2O flux during thawing of frozen temperate forest soils depends on soil pH, WFPS, and the amount of dissolved organic matter released into the soil.
    The stoichiometric characteristics of C, N and P in soil and root of larch (Larix spp.) plantation at different stand ages in mountainous region of eastern Liaoning Province, China.
    ZENG Fan-peng1,2, CHI Guang-yu1*, CHEN Xin1, SHI Yi1
    2016, 35(7):  1819-1825. 
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    The cycling of C, N and P is important in functioning of forest ecosystem. By applying the method of spatial sequence instead of time successional sequence, the contents and stoichiometric ratios of C, N and P in soil and root of larch (Larix spp.) in young (10 a), middleaged (25 a) and mature plantation (50 a) located in the montane region of eastern Liaoning Province, China were studied. The results showed that the contents of soil C, N and P decreased significantly with the increasing stand age. The soil C∶N and C∶P increased with the increase of stand age. The stand age had no significant effect on N∶P in soil. The N, P, C∶N and C∶P in roots changed significantly with the increase of stand age. The contents of N and P in roots decreased significantly with the increasing stand age. The root C∶N and C∶P increased with the increasing stand age. The stand age had no significant effect on the content of C and N∶P in roots. Our results suggested that the soil fertility of larch plantation declined with the increase of stand age. In order to improve soil fertility, regulation of stand structure by thinning and reasonable fertilization should be applied.
    Soil organic carbon stock and active carbon fractions under four kinds of long-term fertilization.
    ZHAO Yu-hao1, ZHANG Yan-jie1, LI Gui-chun2, ZHAO Kai3, LI Zhong-fang4, TANG Zheng4, LU Shun-bao1
    2016, 35(7):  1826-1833. 
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    A long-term field experiment with four kinds of fertilization treatments was conducted in Fuxin of Liaoning Province. The fertilization treatments included: no fertilization (CK), chemical fertilizer (NPK), organic manure (M), and organic manure combined with chemical fertilizer (NPKM). Soil total organic carbon and key active carbon components were analyzed in order to offer a scientific basis for reasonable regional fertilization and sustainable agriculture management. The results showed that the total organic carbon content (TOC), organic carbon stock, microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), labile organic carbon (LOC) contents in NPKM were higher than in the other treatments, and were 40.5%, 38.6%, 114.7%, 57.5%, 103.8%, and 97.6% higher than in the CK treatment, respectively. The MBC in organic manure treatment was obviously higher than that of without organic manure treatment. There were significant positive correlations between TOC, MBC, DOC, POC and LOC (P<0.05). Mixed application of organic and inorganic fertilizers significantly increased soil organic carbon content, indicating that it was the optimal fertilization model to improve soil fertility. The active carbon components responded sensitively to the fertilization and could be used as an index indicating the changes in soil total carbon.
    Characteristics of cellulose degradation after straw return and its influence factors in arable lands in red soil hilly region.
    DONG Ming-zhe1,2, CHEN Xiang-bi1,3, FENG Shu-zhen1,2, YIN Chun-mei1,4, SU Yi-rong1,3*
    2016, 35(7):  1834-1841. 
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    Based on long-term field fertilization experiments in subtropical upland and upland-paddy rotation land, the characteristics of long-term accumulation and annual degradation after long-term chemical fertilization (nitrogen, phosphorus, and potassium) combined with crop straw (NPKS) were compared with those of chemical fertilization (NPK). Meanwhile, the main influencing factors on cellulose degradation were clarified from the sights of key enzyme activities, soil properties and climate factors. The results showed that cellulose was not significantly accumulated after long-term (13 years) NPKS fertilization for both lands. After application of NKPS fertilization, the cellulose content was decreased to its initial level after 3 months and 6 months in rotation land and upland respectively, with the faster degradation rate in the former land. After NPKS fertilization, the increment of the activities of cellulolytic enzymes ((cellobiohydrolase (CBH) and β-glucosidase (βG)) were significantly higher in rotation land than in upland, implying a stronger response of cellulolytic enzyme in rotation land to NPKS fertilization. Besides, the proportions of cellulose in soil organic matter (CEL/SOM) were significantly decreased after long-term fertilization in both lands, suggesting that cellulose was not the key component contributing to the accumulation of SOM in subtropical agricultural lands. Correlation analysis and stepwise regression analysis demonstrated that the β-glucosidase, soil microbial biomass carbon and available nitrogen were the key factors determining cellulose degradation. In the future, fertilization and land-use type could be useful strategies to regulate the transformation of soil organic matter and its components in arable lands in red soil hilly region.
    Characteristics of mercury species in the atmospheric precipitation from Xunyang mercury mining district in Shaanxi Province.
    AO Ming1,2, ZHANG Chao2, WU Yong-gui1, XU Xiao-hang2, QIAN Xiao-li1,2, QIU Guang-le2*
    2016, 35(7):  1842-1848. 
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    Concentrations of total mercury (THg), reactive mercury (RHg), and dissolved gaseous mercury (DGM) in precipitation collected from Xunyang Hg mining district in Shaanxi Province from July 2012 to Septernber 2013 were measured. The trace elements in precipitation were analyzed as well. Results showed that average concentrations of THg, RHg, and DGM were (48±43), (13±9.0), and (3.8±3.6) ng·L-1, with ranges of 4.4-253, 0.39-43, and 0.41-17 ng·L-1, respectively. The fractions of Hg species accounted for 27% in RHg, 7.9% DGM, and 65% in other inorganic forms. The average pH value in rain was 5.4, with a range of 4.2-6.7. Mercury in precipitation exhibited significantly positive correlation with both Sb (R2=0.54) and Se (R2=0.67), indicating a similar source of the three elements due to the Hg mining activities. However, the local coal combustion might be another important source of Hg in wet deposition far from the Hg mining region.
    Spatiotemporal distribution and potential ecological risk assessment of heavy metals in the sediments of Lake Caohai, Guizhou, China.
    SONG Yi-long1,2, ZENG Yan1*, YANG Hai-quan1,2, CHEN Jing-an1, DING Wei3, WANG Jing-fu1, JI Yong-xue1,2, DONG Ze-qin4
    2016, 35(7):  1849-1856. 
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    A total of 19 surface sediments and 5 sediment cores were collected at typical sites in Lake Caohai, located in Guizhou Province. The spatiotemporal distribution and sources of seven heavy metals (Cr, Ni, Cd, Co, Pb, Zn and Sb) in the sediments were investigated, and the potential ecological risks of those heavy metals were assessed. The results showed that the concentrations of Cd, Pb, Zn and Sb in the surface sediments were relatively higher in the north, central and southwest areas of the lake; these pollutants mainly resulted from the mineral exploitation in the catchment. The concentrations of Cr, Ni and Co were relatively higher in the most west area, mainly due to urban sewage discharge (westernmost areas). Based on the geoaccumulation index (Igeo), Cd and Sb were obviously enriched in the sediments of Lake Caohai. The potential ecological risk of Cd was higher in the lake sediments, especially in the sediments from the central part of the lake. The profiles of the variations of heavy metals contents in the sediment cores corresponded well to the history of the mineral exploitation in the catchment of Lake Caohai. Although the mineral exploitation was ended, its remaining problems are still the main cause of heavy metal pollution in Caohai Lake. Therefore, it is necessary to adopt reasonable methods to strictly control the heavy metal pollution and to establish suitable measures to effectively treat the heavy metal pollution, recovering the ecological environment of Lake Caohai.
    Pollution characteristics and ecological risk assessment of heavy metals in the sediments of Shaying River.
    ZHONG Ming, WAN Yun, WAN An, HU Jin, AN Shu-qing, LENG Xin*
    2016, 35(7):  1857-1864. 
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    In order to understand the pollution status of heavy metals in the sediments of Shaying River, we acquired the surface sediments and determined the concentrations of 7 heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in May 2013. The results showed that the average contents of As, Cd, Cr, Cu, Hg, Pb, and Zn were 8.49, 0.35, 51.4, 27.2, 0.094, 26.8, and 111.8 mg·kg-1. Average contents of Cd, Cu, Hg, Pb, and Zn elements were higher than the background values in soils of Henan Province. These five heavy metals were influenced by human activities at varying levels. The heavy metal contamination in sediments estimated by geo-accumulation index (Igeo) followed the order: Cd>Hg>Zn>Pb>Cu>Cr>As. The pollution of Cd was the most serious, and 91.43% of the samples were contaminated by Cd. The result of potential ecological risk index showed that the ecological risk of the heavy metals was: Cd>Hg>As>Cu>Pb>Zn>Cr. Cd showed a very strong risk, Hg was  of strong risk, and the other 5 kinds were of low risk. The heavy metals pollution of Zhoukou section of Yinghe River and its tributaries Jialu River and Qingyi River were prominent, which should arouse the attention of the local environmental protection departments.
    Spatial distribution of phytoplankton community during summer stratification in Lake Fuxian.
    NIU Yuan1, KONG Xiang-Hong1,2, YU Hui1*, LIU Qian1
    2016, 35(7):  1865-1871. 
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    Lake Fuxian is a typical deep oligotrophic lake located in YunnanGuizhou Plateau. In order to explore the spatial distribution characteristics of the phytoplankton community and its influencing factors, stratified sampling, including three sites, was conducted in July 2014. A total of 37 species, belonging to 27 genera, 18 families and 6 phyla, were identified in our survey. The average biomass of phytoplankton across the whole lake was 0.41 mg·L-1, of which Chlorophyta exceeded 70%. Mougeotia sp., which belongs to Chlorophyta, was the absolutely dominant species with a biomass of 0.18 mg·L-1. In horizontal distribution, biomass of phytoplankton was higher in the north than those in the middle and south. In water column, phytoplankton was mainly distributed in epilimnion and thermocline layers with a maximum occurring at a depth of 10 m, and the biomass decreased remarkably in hypolimnion layer. Correlation analysis suggested that biomass of phytoplankton in epilimnion and thermocline layers was mainly influenced by water depth (accompanied with water temperature and light), while in hypolimnion layer the key affecting factors were DO and pH. Redundancy analysis demonstrated that environmental variables well explained the variations in phytoplankton communities. Water temperature, electric conductivity and pH played key roles in structuring phytoplankton communities, while the role of N and P nutrients was not significant.
    Impact of freshwater gastropod (Bellamya aeruginosa) on the zooplankton community in the water body experiencing a cyanobacterial bloom.
    MA Shao-bo, ZHU Jin-yong*, LU Kai-hong, YANG Wen
    2016, 35(7):  1872-1878. 
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    The purpose of this microcosm experiment was to determine whether the freshwater gastropod Bellamya aeruginosa affected zooplankton community in the water body experiencing a cyanobacterial bloom. Three treatments of different snail densities (low, medium, and high) and a control (no snails) were set up. The abundance of zooplankton was determined on days 0, 3, 7, 11, 15, 23, 31, 46, and 61. A total of 52 species from 33 genera were identified, which consisted of 15 species of Protozoa, 28 species of Rotifera, 6 species of Cladoera and 3 species of Copepoda. According to the abundance and occurrence, nauplius, Asplanchra, Polyarthra, and Brachionus were considered as the dominant taxa. Principal response curves showed that zooplankton community in all treatments was consistently different from that in the control. The highest decrease in abundance was found for Keratella cochlearis, K. valga and Difflugia sp. The abundances of these species decreased from 481, 545.3 and 359.7 ind·L-1 to 0.1, 0.1 and 9.2 ind·L-1 in the high density treatment, respectively. The populations of testate amoebae, tintinnid ciliate and rotifer were significantly negatively affected by the snails. Additionally, the presence of snails also caused the increase in the biomass of Cyclops sp. The abundance of Cyclops sp. increased from 46.4 ind·L-1 to 420.1 ind·L-1 in the high density treatment. These results indicate that the presence of snails resulted in a significant change of zooplankton community in cyanobacterial bloom. The dynamic of zooplankton community was more subject to the indirect impact than direct filterfeeding of snails.
    Impact of aquaculture liquid from invasive species apple snails (pomacea canaliculata) on water quality and indigenous species Bellamya aeruginosa.
    FANG Miao1,2, XU Meng1, LUO Du1, GU Dang-en1, YANG Ye-xin1, MU Xi-dong1, HU Yin-chang1, LUO Jian-ren1*
    2016, 35(7):  1879-1888. 
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    Using water lettuce (Pistia stratiotes), water hyacinth (Eichhornia crassipes) and southern naiad (Najas guadelupensis) as apple snails’ (Pomacea canaliculata) food, we determined the temperature, pH, dissolved oxygen and the concentrations of ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, and soluble phosphate of aquaculture liquid at 1, 3, 5, 7, 9 days when different number snails were bred (0, 2, 4, 8, 16, 32). Then, a manipulative experiment was carried out to test the effects of aquaculture liquid of apple snails on the growth and mortality of Bellamya aeruginosa and P. canaliculata. It was found that apple snails’ breeding numbers and types of feeding food had very significant influence on dissolved oxygen, ammonium nitrogen, nitrate nitrogen and soluble phosphate (P<0.01). Dissolved oxygen was significantly decreased with the increase of breeding numbers and cultivation time, while the concentrations of ammonium nitrogen, nitrate nitrogen and dissolved phosphate increased significantly (P<0.05). The nitrite nitrogen concentration was significantly affected only by breeding numbers (P<0.05). In the manipulative experiment, on base of relative growth and mortality rate, apple snails’ aquaculture liquid had significantly different influence on P. canaliculata and B. aeruginosa (P<0.05); the growth rate of P. canaliculata decreased while B. aeruginosa had negative growth. Furthermore, the mortality rate of B. aeruginosa became greater with the increasing concentration of aquaculture liquid. This study indicates that apple snails can change the physical and chemical properties of breeding water quality through their aquaculture liquid. The aquaculture liquid of P. canaliculata can restrain the growth of B. aeruginosa and hasten its mortality, which may be an important invasive mechanism of apple snails. Our study not only enriches the theory of invasion ecology, but also possibly provides experimental basis for ecological risk assessment of apple snails.
    The influences of light color on growth, haematological and biochemical indices of juvenile Plectropomus leopardus.
    CHEN Wan-qing1,2, LIU Zhi-ming1,2, WU Liang1,2, WANG Yao-hua2,3, MA Jian-zhong2,3, WU Hong-xi2,3*
    2016, 35(7):  1889-1895. 
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    To evaluate the effects of light color on the growth of juvenile Plectropomus leopardus and its biochemical indices of serum, using different breeding tanks in a small circulating water aquaculture system, five lighting conditions, namely white light, red light, yellow light, green light and dark were set for the cultivation experiment for 120 days, in which the size of fish was initially 19.67±1.26 cm with the body weight of 92.92±4.05 g. The results indicate that light color had significant effects on the growth and survival of juvenile P. leopardus. The green light group had the highest survival rate and body weight, and the white light group had the highest hepatosomatic index (HSI). The white light group had lower contents of blood sugar, blood lipids and proteins, while it had higher alanine aminotransferase (ALT), aminotransferase (AST), and lactate dehydrogenase (LDH) than the other four groups, especially the LDH from the white light group was significantly higher than those in the red light and green light groups. Juvenile fish in the white light group had the higher creatinine (CREA) and blood urea nitrogen (BUN) than those in other four groups (P<0.05). Except Mg2+, the contents of inorganic ions, including Ca2+, P3+, Na+, K+ had no significant difference among the five light groups. In conclusion, green light was the best for the growth and survival of P. leopardus.
    Resources of breeding birds in Guangxi.
    YI Jian-feng, YU Li-jiang
    2016, 35(7):  1896-1910. 
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    Species richness and composition of breeding birds in Guangxi Province were evaluated based on the publications and field records (updated to 2015). A total of 428 breeding species were recorded in Guangxi Province, which belong to 20 orders and 67 families. 81.07% of them are residents (347 species). Aquila chrysaetos, Tragopan caboti, Syrmaticus ellioti and S. humiae are listed as grade I national protected species in China. Sixtyeight species are listed as grade Ⅱ national protected species. Twenty species are listed in the IUCN Red List, including 2 Endangered, 8 Vulnerable and 10 Near Threatened. More species were found in Oriental realm (77.34%) than in Palearctic realm (7.24%) and in both realms (15.42%). 89.02% species, mostly Oriental species (72.43%), prefer woodland, whereas species in Palearctic realm and both realms are generalists. A high number of species were found in southwestern Guangxi and coastal area of southern Guangxi, and accounted for 82.24% and 61.21% of all breeding species in the province, respectively. Thus, these areas, particularly woodland habitats, should be considered with conservation priority.
    Egg color and its intra and interclutch variation of a barn swallow (Hirundo rustica) population in Changjiang, Hainan, China.
    NIU Nan1, HUO Juan1, SU Tong-ping1,2, YANG Can-chao1, LIANG Wei1*
    2016, 35(7):  1911-1915. 
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    Quantization of egg color and intra and interclutch variation plays an important role in understanding the evolution and adaptability of bird egg coloration. Host species utilized by cuckoos have less variation in egg appearance within a clutch and more variation between individuals while species with no history of cuckoo parasitism present opposite properties. In this study, fiber spectrophotometer was used to quantitatively analyze the egg color of a barn swallow (Hirundo rustica) population in Changjiang, Hainan, China. Egg reflectance of ground color in barn swallows was higher than that of the pattern color. The egg pattern reflectance had higher wave crest and lower wave vale, which indicated that egg pattern had bigger color saturation than ground color. Although ground and pattern colors look obviously different by human eyes, avian visual modeling showed that their difference in hue (red, green and bluesensitive cones, RGB) was not statistically significant. However, the chroma, brilliance and ultraviolet (UV) of barn swallow eggs were highly different between ground color and pattern. The intraclutch variation between ground color and pattern was not statistically different. As to the interclutch variation, the hue RGB of pattern was higher than that of the ground color while the UV, chroma and brilliance were not statistically different. To our knowledge, this is the first quantitative study of barn swallow egg coloration.
    Progress in researches of the response of plant functional traits to grazing disturbance.
    ZHAO Na1,2, ZHAO Xin-quan1,2,3, ZHAO Liang1,2, XU Shi-xiao1,2*, ZOU Xiao-yan1,2
    2016, 35(7):  1916-1926. 
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    Grazing is a major mode of grassland use. Plants are likely to respond positively to grazing disturbance through changes in their functional traits. The researches of plant traits mainly focus on different responses of ecological traits of aboveground functional components, such as stem and leaf, to grazing disturbance. The changes of plant traits reflect the adaptive strategy of maximum resources gain rate, and even are specific manifestation about their own unique survival strategy under grazing pressures. This research method, based on individual ecological characteristics, makes up for some deficiencies of the traditional classification method and is an important tool to study grazing disturbance ecology, and even has the important significance of ecology and evolutionary biology. This paper introduces the definition of plant functional trait and its assembly pattern, summarizes the phenotypic plasticity of plant functional traits, sums up their tradeoff strategy under different grazing intensities, emphasizes the unique value of individual plant functional traits to grassland use, and ultimately puts forward the existing problems and development direction in the future.
    A review on litter decomposition and influence factors.
    CHEN Ting, XI Min*, KONG Fan-long, LI Yue, PANG Li-hua
    2016, 35(7):  1927-1935. 
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    We summarized the process, characteristics and influence factors of litter decomposition, including the stage division of decomposition, the mass loss and changes of components and character of decomposing litter. The decomposition of litter includes physical leaching, biochemical decomposition, and fragmentation. Physical leaching and biochemical degradation are dominant in the early and later stages of decomposition, respectively. Litter decomposition shows characteristics of continuity and stage, with mass loss of being fast at first and then being slow. The humification is strengthened with the accumulation of substances which are decomposed difficultly, resulting in the enhancement of aromaticity and adsorption and the decrease of biodegradability. Nutrient concentrations change greatly during decomposition. The content of C element is generally decreased, while P and N are either accumulated or released, which are influenced by many factors. Litter decomposition is a process influenced by multiple factors. Overall, litter property is essential to the decomposition. Temperature, water, soil animal community can have distinct impacts on the decomposition. To a certain degree, increased moisture and temperature can accelerate the decomposition by promoting leaching process and microbial activity. Soil organisms have a significant contribution to the decomposition of litter. The role of microorganisms during decomposition is dominant and the soil animals play a supplementary role. Thus, studies on litter decomposition in the future should focus on the decomposition mechanism, the interaction between the factors, and the feedback of litter decomposition on the ecological changes.
    Estimation of wetland vegetation aboveground biomass based on remote sensing data: A review.
    ZHAO Tian-ge1, YU Rui-hong1*, ZHANG Zhi-lei2, BAI Xue-song1, ZENG Qing-ao1
    2016, 35(7):  1936-1946. 
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    Wetland vegetation biomass is a key factor to measure the fitness of wetland ecosystem. How to estimate biomass is one of the most hotspot topics in the wetland research. The general methods of estimating the vegetation aboveground biomass mainly depended on quadrat, which is limited when dealing with complicated wetland ecosystem. With the progress of remote sensing, the observation of wetland vegetation biomass has turned into a long-lasting, dynamic and largescale manner. After analyzing a large amount of related references, we illustrated theoretical basis and calculation principle of the estimation of wetland vegetation aboveground biomass, based on optical remote sensing image, SAR data, Lidar data and multisource, using remote sensing data as data source. We summarized the research progress, analyzed the applicability and limitation of the methods. Then, we described the developing trend in study on wetland vegetation biomass in several aspects, such as expanding the monitoring type of wetland vegetation biomass, integrating the multisource remote sensing data, assimilating the remote sensing data and developing the remote sensing mechanism models.
    Progress on phosphate oxygen isotope technology in environmental science.
    TIAN Li-yan1,2, GUO Qing-jun1*, HE Hui-jun3, LANG Yun-chao4, HU Jian4, YANG Jun-xing1, WEI Rong-fei1,2, HAN Xiao-kun1,2
    2016, 35(7):  1947-1956. 
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    Recently, environmental pollution caused by phosphorus (P) loss has become an increasingly serious problem. Therefore, it is significant to identify the sources, migration and transformation of P in the environment. The oxygen isotope composition of phosphate (δ18OP) represents a powerful tracer, which has been widely used for investigations of aquatic ecosystems, soils and paleoenvironments. This article discusses the δ18OP composition of natural substances and related fractionation mechanisms as well as the separation and purification of phosphate from environmental samples and introduces the application of δ18OP analyses in environmental science. According to the progress and problems of previous research, some modifications and improvements should be put forward for future studies: The methods of separating and purifying of δ18OP should be selected according to the sample properties; fractionation mechanisms and applied prospects of δ18OP in environment need to be further studied.
    Estimation of Phyllostachys edulis forest biomass in southern Wuyishan Mountain using allometric equation and geostatistical technique.
    ZHANG Yu, YUE Xiang-hua, QI Liang-hua, JIANG Ze-hui, SHI Lei*
    2016, 35(7):  1957-1962. 
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    The allometric equations of biomassdiameter at breast height (DBH) and stand biomass densityleaf area index (LAI) of Phyllostachys edulis forests are helpful for biomass estimation with great accuracy. Here, the two fitted allometric equations, together with geostatistical technique, were employed to estimate biomass of moso bamboo forest in Huangkeng Town, southern Wuyishan Mountain, Fujian Province. A total of 103 moso bamboo culms were cut in Huangkeng Town to fit the allometric relationship between aboveground biomass and DBH at individual level. Standlevel LAI was derived from fisheye camera, which was used to develop equation between stand biomass density and LAI. Then geostatistical technique was used to estimate biomass of moso bamboo forest of the whole town. Significant power function relationships were found between aboveground biomass and culm DBH (R2=0.585, P=0.002), and between stand biomass density and LAI (R2=0.525, P=0.002). Based on the two fitted allometric equations and geostatistical technique, the mean biomass density of moso bamboo forest in Huangkeng Town was estimated as 53.49 t·hm-2, and the total biomass of the whole town was 0.62 Tg.
    Prediction of the bioavailability of PAHs in earthworms by Tenax-TA and solid phase microextraction. 
    LI Na1,2, GUO Mei-xia1,2, GONG Zong-qiang1*, ZHAO Ran-ran1,3
    2016, 35(7):  1963-1969. 
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    In order to accurately predict the bioavailability of PAHs in coking plant soil, Tenax-TA extraction of PAH fast desorption fraction and solid phase microextraction (SPME) were applied in this study to predict the PAHs concentration in earthworms (Eisenia fetida), and the data were compared with measured PAHs concentration in earthworms to analyze their difference and correlation. The results showed that the PAHs concentrations measured in earthworms were linearly related with those in bulk soil and those predicted by SPME and Tenax (R2=0.88, 0.55 and 0.94, respectively). There was no relationship between the PAHs concentration in earthworms and that in soil pore water predicted by SPME. While SPME somewhat overestimated PAHs concentration in earthworms, Tenax predicted it with a ratio nearly to 1∶1, which indicates that Tenax-TA  extraction of PAH fast desorption fraction in coking plant soil may serve as a better predictor to assess PAHs bioavailability. Our results provided a theoretical basis for the environmental risk evaluation and remediation of PAHs polluted soil.
    Hydrological responses to land use change under three future scenarios in Luanhe River Basin.
    LI Ying, HUANG Sui-liang*
    2016, 35(7):  1970-1980. 
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    According to the related planning, CLUE-S model was applied to simulate and analyze the future characters of land use changes under three future scenarios (i.e., trend scenario, economic development scenario, and ecological protection scenario) in the Luanhe River Basin. Accordingly, hydrological processes, such as surface runoff, groundwater flow, and sediment yield under the three scenarios, were explored by the SWAT model. At the same time, we revealed the differences of hydrological characters and identified the critical areas of sediment yield under the three scenarios in the Luanhe River Basin. The results showed that the hotspots of construction land expansion could be located in the vicinity of Chengde City in the midstream of the Luanhe River Basin under the three scenarios in 2030. Different characters of hydrological processes in the different scenarios were observed. The annual average surface runoff (11.34 mm·a-1) was the smallest under the ecological protection scenario, equaling to 47.51% and 46.02% of that under the trend scenario and ecological protection scenario, respectively. The annual average groundwater flow (7.94 mm·a-1) was the smallest under the economic development scenario, equaling to 51.90% and 23.26% of that under the trend scenario and ecological protection scenario, respectively. The annual average sediment yield was the smallest under ecological protection scenario, being 0.35×105 kg·km-2·a-1. Compared with the trend scenario and economic development scenario, annual average sediment yield was obviously reduced by 60% under the ecological protection scenario. The ecological protection scenario was most suitable for soil and water conservation. Under the trend scenario, soil erosion was the strongest, while the economic development scenario had the worst water conservation. Therefore, the current land use planning can be implemented in the Luanhe River Basin, but the partitioning management should be implemented based on spatial distribution of soil erosion. Additionally, critical source areas of sediment yield should be carefully monitored and managed.