Chinese Journal of Ecology

Effects of nitrogen addition and increased precipitation on metal pools in temperate steppe, northern China.

LIU Ze-rui1, WANG Jun-jian2, WAN Shi-qiang3, ZENG Hui1*

2016, 35(5): 1125-1131.

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This study investigated the total concentration and three chemical fractions (exchangeable, carbonate, and organic fractions) of soil metals (Mn, Cr, V, Pb, Ni, Cu, Co and Cd) with simulated nitrogen addition and increased precipitation in a temperate steppe site in Duolun, Inner Mongolia. After nine years of nitrogen addition, increased precipitation and their interaction treatments, no statistically significant effect was observed on the total concentrations of soil metals. Only the concentrations of the exchangeable fraction of Mn, Pb, Ni, Co, and Cd, and the organic fraction of Cr were significantly decreased (P<0.10). In conclusion, longterm nitrogen addition and increased precipitation have limited effect on soil metal concentrations and their chemical fractions. The metalrelated soil environmental quality in the studied semiarid temperate steppe is relatively stable in response to increasing atmospheric nitrogen deposition and precipitation within nine years; however, more attention should be paid to the possible change in the exchangeable fraction of soil metals.

Soil microbial carbon source utilization and functional diversity of typical native broadleaved plantations in south subtropical China.

CHEN Chao-fan1, WU Shui-rong2, QIN Lin1*, FAN Yao-cheng1, TAN Ling1, GUO Wen-fu3

2016, 35(5): 1132-1139.

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Understanding soil microbial carbon source utilization and functional diversity of typical native broadleaved artificial forests is of great importance in tree species selection for vegetation restoration and reconstruction of hilly red soil areas in south subtropical China. By using BiologEco technology, we studied the soil microbial carbon source utilization and functional diversity at different soil depths (0-20, 20-40 and 40-60 cm) of four typical native broadleaved planted forests (Castanopsis hystrix, Mytilaria laosensis, Michelia macclurei and Paramichelia bailonii) and exotic fastgrowing eucalyptus plantation in the Fubo Forest Farm in Pingxiang, Guangxi. The results showed that the optimum incubation time for the capacity of soil microbes using monocarbon source in the five planted forests was 108 h. The capacity of soil microbial carbon source utilization of the different planted forests increased with the incubation time, and decreased with the soil depth. At the incubation time of 108 h, the capacity of soil microbial carbon source utilization among the four native broadleaved planted forests had no significant difference, but it was higher than that of the eucalyptus plantation. The Shannon index and Simpson index indicated that the functional diversity of soil microbial community of the four native broadleaved planted forests were different at various soil depths, and they were higher than those of the eucalyptus plantation at the same soil horizon. The principal component analysis and cluster analysis of 31 carbon sources indicated that carbohydrate, amino acid, polymerizer, carboxylic acid and aromatic carbon were sensitive carbon sources to the functional diversity of soil microbial communities in the different planted forests.

Carbon and nitrogen contents in calcareous soil aggregates affected by disturbance and land use in karst region, China.

XIAO Shuang-shuang1,2,3, YE Ying-ying1,2,3, ZHANG Wei1,2, WU Min1,2,3, WANG Ke-lin1,2*

2016, 35(5): 1140-1146.

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Carbon and nitrogen contents in aggregates are influenced greatly by human disturbance and land use. However, it is uncertain how disturbance and land use affect carbon and nitrogen in aggregates, especially for calcareous soil in karst region in southwest China, where is extremely vulnerable to human disturbance. Based on a longterm field trial in Huanjiang Observation and Research Station, this study identified the distribution characteristics of carbon and nitrogen in calcareous soil aggregates under five kinds of disturbance and land use treatments (enclosure, cutting, burning, pasture, and maize cropland). The results showed that the aggregate composition was dominated by particles >5 mm and 2-5 mm under the different disturbance and land uses. The aggregates of enclosure and cutting lands showed significantly higher values in particles >5 mm than those of the other three landuse patterns, while burning land and maize cropland had high values in <2 mm fraction. In whole soil and all size classes of aggregate particles, enclosure had the highest values of organic carbon and total nitrogen, followed by burning and cutting, while the values of organic carbon and total nitrogen in pasture and maize cropland were relatively lower. The distribution patterns of carbon in different aggregates were variable: enclosure and cutting presented an undulation distribution, and maize cropland showed an inverted “V” shape. The lowest values of organic carbon and total nitrogen appeared in particles 0.054-0.25 mm. The contribution of organic carbon and total nitrogen in >5 mm fraction under enclosure and cutting was significantly higher than that under the other three landuse patterns. Most of the organic carbon and total nitrogen were accumulated in >5 mm and 2-5 mm fractions, which both accounted for 60%-82%. The results suggest that particles of aggregate size >2 mm hold the major parts of the soil carbon and nitrogen in karst calcareous soils. Our findings could provide fundamental information for choosing proper management practices to improve soil fertility as well as carbon and nitrogen sequestration.

Responses of volatile halogenated organic compounds fluxes from forest floor to simulated nitrogen deposition in Dinghushan.

WU Wang-wang, ZHENG Li-li, HUANG Xing-ran, HU Bao-ye, YI Zhi-gang*

2016, 35(5): 1147-1153.

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Volatile halogenated organic compounds (VOX) are known as atmospheric pollutants which contribute to stratospheric ozone depletion and global warming. Although ocean is considered to be the major source and sink of VOX, VOX from forest ecosystems still have significant effect on global VOX cycle. Increasing global nitrogen deposition plays a great role in structure and function of forest ecosystems, leading to changing of VOX uptake and emission from forest floor. Static chamber coupled with preconcentratorGC-MS technique was employed to study the responses of VOX fluxes from forest floor with simulated elevated nitrogen deposition in two major forests, namely pine forest (PF) and monsoon evergreen broadleaf forest (BF) in Dinghushan. The results showed that PF floor acted as sink for VOX at the control sites, with the maximum uptake rate of -428.32 pmol·m^-2·s^-1 for 1,1,2trichloroethane. The uptake rates of VOX decreased with enhanced nitrogen deposition, and the medium nitrogen addition had a significant influence on VOX flux in PF, with the change from sink to source. BF floor acted as source for VOX at the control sites. The emission rates of VOX decreased with enhanced nitrogen deposition, with a significant difference between the control and nitrogen addition sites, and BF forest floor changed from source to sink for some VOXs. Significant differences were found between forests at the control sites, but the difference diminished or even disappeared with nitrogen addition. Significant correlations were observed between vinylchloride and 1,2dichloropropane and 1,1,2trichloroethane at nitrogen addition sites in PF. In BF, significant correlations were also found between chloromethane and vinylchloride, chloroethane and chlorobenzene, and between chlorobenzene and most tested VOXs. These results indicated the same mechanism of response of the tested VOXs to nitrogen deposition in forest floor. There were no obvious diurnal variations for VOX fluxes at the control site, but a small emission peak appeared at 07:00 and the highest uptake rates were observed at 13:00 for most of the VOXs at high nitrogen addition sites in BF.

Variation characteristics of water vapor flux in Anji Phyllostachys edulis forest ecosystem.

SHU Hai-yan1, JIANG Hong1,2*, CHEN Xiao-feng2, SUN Wen-wen2

2016, 35(5): 1154-1161.

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To reveal the water use ability of Phyllostachys edulis and further provide theoretical guide for its water management, eddy covariance observation technology was used to obtain water vapor flux data and rain gauges were applied to gaine precipitation data of P. edulis forest ecosystem in Anji County, Zhejiang Province from 2012 to 2014. The results showed that water vapor fluxes were positive during 2012-2014, indicating the ecosystem was a good water vapor source for the atmosphere. Water vapor fluxes were 695.96, 749.07 and 656.47 kg·m^-2 in 2012, 2013 and 2014, respectively. Meanwhile, the maximum value occurred in July, and the minimum in December. Water vapor flux presented a seasonal variation, being summer > spring > autumn > winter (except spring < autumn in 2014). Monthly precipitation showed a good positive correlation with monthly evapotranspiration in the three years (r=0.67, P<0.05). In addition, both precipitation and evapotranspiration maximally occurred during the period from June to August. The total precipitation amounts were 2018, 1509 and 1476 mm in 2012, 2013 and 2014, soil moistures at depth of 5 cm were 3.173, 3.045 and 3.013 m³·m^-3, and water use efficiencies (WUE) were 2.84, 2.10 and 3.37 g·kg^-1, respectively. Annual evapotranspiration accounted for 34.49%, 49.66% and 44.48% of annual total precipitation for the three years, respectively, suggesting that the runoff of P. edulis forest was greater, with a lower WUE. Moreover, vapor pressure deficit and air temperature had significant effects on the WUE of P. edulis forest, which indicated that the asynchronization of water and heat was the main limiting reason of high WUE. It is recommended that the regulation of temperature and humidity (high temperature and high humidity or the opposite) should be conducted when managing the forest, so as to improve the WUE and production of P. edulis and avoid the waste of water resource.

Spatiotemporal characteristics of CO₂ concentration in Phyllostachys edulis forest in Anji during growing season.

CHEN Xiao-feng1, JIANG Hong1,2*, SUN Wen-wen1, SHU Hai-yan3, FANG Cheng-yuan1, SUN Heng1

2016, 35(5): 1162-1169.

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The CO₂ concentration of Phyllostachys edulis forest ecosystem during the growing season (from May to October) was continuously measured using a 7layer profile system in Anji, Zhejiang Province in 2011. The synchronized CO₂ flux and meteorological data were applied to explore the temporal and spatial variations in the CO₂ concentration and CO₂ storage flux. The results showed that the CO₂ concentration of P. edulis forest during the growing season exhibited obvious diurnal and seasonal variations, as well as vertical variations. In a single day, the CO₂ concentration reached the maximum value at the daybreak, and decreased to the minimum value in the afternoon after a rapid emission process. In the entire growing season, the minimum CO₂ concentration of the forest appeared in July (368.1 μmol·mol^-1), and the maximum one emerged in October (402.6 μmol·mol^-1). What’s more, the CO₂ vertical gradients above the canopy were lower than those in and below the canopy. The vertical gradients in and above the canopy showed a consistent variation trend: positive in the daytime (carbon sink) and negative at night (carbon source). However, the CO₂ vertical gradients below the canopy were negative throughout the day. We found the proportion of the CO₂ storage flux obtained from the profile system to net-ecosystem CO₂ exchange (NEE) was 25.5% and 8.9% at a halfhour and daily scale, respectively, but was only 0.22% at a monthly scale. The results suggested that CO₂ storage flux could not be neglected when NEE was estimated at a halfhour or daily scale, but could be ignored at a monthly or longer time scale.

HAN Ling, ZHAO Cheng-zhang*, FENG Wei, DUAN Bei-bei, XU Ting, ZHENG Hui-ling

2016, 35(5): 1170-1176.

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The resource allocation pattern between leaf and flower in the process of plant growth is formed by the long-term interaction between plants and the environment, reflecting the comprehensive function of diversity. By using the ArcGIS established regional digital elevation model (DEM) and the method of standardized major axis estimation (SMA), this paper studied the relationship between the leaf and flower growth of Zygophyllum xanthoxylum population at different slope aspects on the northern slope of Qilian Mountains, Northwest China. The results showed that, with the slope aspect turning from north to east, west, and south, the plant density, height, aboveground biomass and soil moisture content of the plant community, the currentyear twig biomass, flower size, leaf area and leaf number of Z. xanthoxylum decreased, while the reproductive allocation increased. Significant positive relationships between the flower size and leaf area and leaf number were found at all slope aspects (P<0.05), the slope of the regressions was significantly less than 1.0 (P<0.01), and the growth speed of flower size was greater than those of leaf number and leaf area. With the aspect turning from north to east, west, and south, the allometric slope of leaf area and flower size decreased, and the allometric slope of leaf number and flower size increased. Slopeinduced gradual changes of environmental factors and vegetation community influenced the growth rates of leaf and flower of Z. xanthoxylum. This relationship reflected the phenotypic plasticity and the resource tradingoff mechanism of growth/reproduction of desert plants in coping with the environmental heterogeneity.

Effects of planting densities on the growth and space utilization of young Cunninghamia lanceolata plantation.

JIA Ya-yun1,2, HE Zong-ming1,2, ZHOU Li-li1,2, MA Xiang-qing1,2*, WU Peng-fei1,2, ZOU Xian-hua1,2, LIU Qing-qing1,2, LIU Yu-hui3

2016, 35(5): 1177-1181.

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In order to explore the effects of planting densities on the growth and spatial utilization of young Cunninghamia lanceolata plantations, an investigation was conducted in 8 years old C. lanceolata plantations with different planting densities (2400, 3100, 3400, 4200 and 4400 trees·hm^-2). The average height, DBH, individual volume and stand volume all decreased after an initial increase. The average height reached the maximum (9.87 m) when the stand density was 3400 trees·hm^-2. The average DBH and individual volume were the highest at the stand density of 3100 trees·hm^-2. The maximum stand volume was found at the density of 4200 trees·hm^-2. With the increase of stand density, clear bole height increased, while the crown width, leaf area per plant and leaf area index all decreased. The root range and root biomass per plant increased with increasing the stand density, while root depth and coarse root density had the opposite pattern. The fine root density increased to the maximum of 46.19 g·m^-3 at the density of 3400 trees·hm^-2, and then decreased gradually. The competition for space among individuals became more intense with the increase of age, and higher stand density limited the individuals’ growth and development. By timely thinning and tending, the stand could keep reasonable spatial structure at different developmental stages to obtain the best timber yield.

Spatial pattern analysis of individuals in different ageclasses of Picea crassifolia.

ZHANG Hua1,2*, HUANG Qin1, ZHAO Chuan-yan2, ZHANG Lan1, XU Chun-hua1, KANG Ya-rong1

2016, 35(5): 1182-1187.

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A plot (100 m×70 m) of Picea crassifolia stand was set up in Tianlaochi catchment of the Qilian Mountains, to analyze the spatial distribution pattern of different age classes and the spatial correlation based on point pattern analysis. The results showed that: (1) The age structure of P. crassifolia was relatively stable, being in a slight growing trend. (2) The ageclass Ⅰ showed aggregated distribution at different spatial scales; the ageclass Ⅱ showed aggregated distribution within 0-31 m, while showed the random distribution at >31 m scale. An aggregation distribution pattern was found at scales from 6-24 m, and random distribution patterns at the other scales for the ageclass Ⅲ individuals. On the whole, the spatial pattern showed random distribution with the increase of P. crassifolia’s age. (3) The correlation between the ageclass Ⅰ and the ageclass Ⅱ was significantly negative at 0-20 m spatial scale, gradually weakened at 20-23 m, but became positive over 23 m. The ageclass Ⅰ and ageclass Ⅲ individuals presented significantly negative correlations at all spatial scales. Ageclass Ⅱ and ageclass Ⅲ individuals showed negative correlations at any scale. Based on the large number and gathered distribution of young individuals at a small scale, we should take thinning to reduce the survival pressure and expand living space of remaining individuals, from a longterm perspective.

Species diversity of shrub communities in typical areas of the Xinjiang Irtysh River watershed.

ZHANG He-yu1,2, ZHOU Hua-rong1,2*, YE Qin1,2, WEN Bin1.2

2016, 35(5): 1188-1196.

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This study aimed to investigate the species composition, species diversity of shrub communities under “mountaindesertoasis” landscape configuration in an arid region of Xinjiang. According to quadrat sampling, shrub communities were classified by TWINSPAN classification method, and the community diversity indexes were calculated. A total of 185 species were identified, including 44 shrub species and 141 herb species, belonging to 123 genera and 33 families. Most of plants belonged to Rosaceae, Compositae and Chenopodiaceae, which were the dominant families in arid regions of northwest China. The flora of shrub species was dominated by the North temperate, the ancient Mediterranean and West Asia to Central Asia components. Shrub communities could be divided into 9 types of shrub community or shrub landscape, including plain and valley shrub, montane scrub and plain desert type. The Shannon diversity index, Pielou evenness index and species richness index showed a similar pattern, being opposite to the dominance index. Moreover, with the increase of the altitude, the Shannon diversity index, Pielou evenness index and species richness index showed a single peak distribution pattern. Our results indicated that the shrub community structure in the study area was relatively simple, the compositional species were relatively few, and the species distribution was not uniform, which may be related to the geographical background and the habitat conditions of shrub plants in arid areas.

Community heterogeneity of undergrowth vegetation in Pinus tabuliformis forest on the Loess Plateau of Northwest China.

WANG Shi-xiong1, ZHAO Liang1, LI Na1, GUO Hua2, WANG Xiao-an2*, DUAN Ren-yan3

2016, 35(5): 1197-1203.

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Community heterogeneity has particular relevance for explaining ecological patterns in fragmented habitats. Using compositional heterogeneity as a measure of community heterogeneity, community heterogeneity patterns were investigated for pine plantations (Pinus tabuliformis) in the Ziwu Mountains of Loess Plateau, Northwest China. The patterns of two community heterogeneity components (i.e. nestedness component and turnover component) were also assessed using additive partitioning. The results showed that: (1) the pine plantations generally displayed high community heterogeneity, which increased with the quantity of spatial grains (i.e. sampling units) and eventually approached to a stable state; (2) both species turnover and nestedness component had significant effects on community heterogeneity, and the former played a dominant role at all scales and layers; (3) habitat heterogeneity was significantly positively correlated to both community heterogeneity and its turnover component, and explained a larger proportion of their variations (71%-84%); by contrast, it was significantly negatively correlated to the nestedness component, and accounted for a smaller proportion of the nestedness component variation (25%-44%). The dominance of the spatial turnover component suggested the potential conservation values of all sample plots for pine plantations, and higher habitat heterogeneity was necessary for restoring species diversity of plantations.

Species composition and diversity characteristics of Excentrodendron hsienmudominated communities in southwestern Guangxi, China.

SHEN Wen-hui*, TAN Zhang-qiang, HE Qin-fei, PENG Yu-hua, ZHENG Wei, HE Feng

2016, 35(5): 1204-1211.

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Studies on species composition and biodiversity pattern of Excentrodendron hsienmudominated communities in Karst Mountain can provide certain basis for the vegetation restoration, and the protection and reasonable use of E. hsienmu in karst area. We investigated the species composition and diversity characteristics of E. hsienmudominated communities at eight sites in Southwestern Guangxi, China. The results showed that there were 248 vascular species belonging to 95 families 164 genera in the communities of the eight sites with the tree layer species being more abundant. The main accompanying species were Orophea anceps, and Sterculia nobilis. In addition to species occurring in the tree layer, there were such species as Schefflera octophylla, Alchornea trewioides in the shrub layer. The pteridophyte was the dominant species in the herb layer while the main liane in the interlayer was legume plants. The Shannon, Simpson and evenness indexes maintained consistent trends in the different layers at the eight sites. The E. hsienmu forest communities at different sites showed certain similarity, and those who were geographically relatively closed showed higher similarity. The communities in Napo, and Longzhou Nonggang were more stable in terms of the biodiversity indexes of the tree layer.

Effect of different fertilization regimes on content of fixed ammonium in soil.

FAN Shao-bo1,2, MA Qiang1, JIANG Chun-ming1, PAN Fei-fei1,2, ZHOU Hua1, XU Yong-gang1, YU Wan-tai1*

2016, 35(5): 1212-1218.

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The aim of this study was to investigate the effect of different fertilization regimes on contents and dynamics of soil fixed ammonium in the low reach of Liaohe River plain based on a longterm insitu experiment (22 years), including six treatments, i.e. CK (unfertilized control), M (recycled pig manure), NP (mineral fertilizer NP), NPK (mineral fertilizer NPK), NPK+M (recycled pig manure with mineral fertilizer NPK), and PK (mineral fertilizer PK). The results showed that the contents of soil fixed ammonium in the different fertilization treatments all decreased and then leveled off. Compared to the initial value, the release of soil fixed ammonium ranged from 18.0% to 38.7% in the different treatments. Application of nitrogen fertilizer would reduce the content of soil fixed ammonium, while potassium could retard the release of fixed ammonium. Recycled pig manure applied alone had no significant effect on the content of fixed ammonium, whereas combined application of recycled pig manure and NPK could increase crop yield, as well as maintain a high level of fixed ammonium, helping to build a great soil nitrogen pool. Therefore, it can be suggested that application of recycled manure coupled with N, P and K fertilizers is an optimum fertilization regime in this region.

Effects of moss-dominated biological soil crusts on soil respiration in two types of soil in the Loess Plateau of Northern Shaanxi Province, China.

ZHAO Dong-yang1, XIAO Bo2,3*, GUO Cheng-jiu1, JIA Yu-hua1

2016, 35(5): 1219-1225.

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The soil respiration rates of sandy soil (Ust Sandic Entisols) and sandy loam soil (Los Orthic Entisols) with and without the coverage of mossdominated biological soil crusts (moss crusts) were measured by a portable CO₂ analyzer (LI-840) in a small watershed on the Loess Plateau of China. The effects of moss crusts on soil respiration were determined by the differences of soil respiration rates with and without moss crusts. The results showed that, on hourly scale, the soil respiration rates of the two soils without moss crusts had similar peak values at 14:00, which were 2.49 and 2.66 μmol·m^-2·s^-1, respectively. The presence of moss crusts decreased the soil respiration rates of the two soils by 8.6% and 5.8%, respectively. On daily scale, the daily soil respiration rates of the sandy soil and sandy loam soil were 9.1% and 5.3% lower with moss crusts than those without moss crusts, respectively; while with the presence of moss crusts, the daily soil respiration rate of the sandy soil was 7.1% lower than that of the sandy loam soil. In addition, the soil respiration rates of the two types of soil had a significant relationship with surface (2 cm) soil temperature, implying that surface soil temperature had important influences on the respiration of the two soils with and without moss crusts. Therefore, we speculated that the moss crusts possibly decreased the soil respiration rate through their effect of decreasing soil surface temperature, with an average reduction of 0.3-0.5 ℃ during the experiment. In conclusion, the moss crusts, especially developed on sandy soil, significantly decreased soil respiration on the Loess Plateau of China. Thus, biological soil crusts should be considered in the regional estimation of CO₂ flux and carbon cycling in the Loess Plateau of China and other similar environments.

Effects of genotypic diversity of Leymus chinensis population on soil macrofauna and microorganism community.

SHEN Jun-fang, XIN Xiao-jing, ZHAO Nian-xi*, GAO Yu-bao

2016, 35(5): 1226-1232.

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Whether genotypic diversity within a dominant species plays a pronounced role in community and ecosystem processes similar to species diversity is a hot research topic in population ecology. Such studies will benefit the conservation and restoration of population or community. We collected soils from the previously established Leymus chinensis populations of different genotype combinations (1-, 3-, 6-genotype) under different interference intensities (no mowing, 10 cm stubble and 5cm stubble), to study the effects of genotypic diversity of L. chinensis population and the interferences on community composition and structure of soil macrofauna and phospholipid fatty acid (PLFA) biomarkers of soil microorganisms. The results showed that the interaction of genotypic diversity and disturbance intensity significantly impacted the amounts of groups and individuals of soil animals (P<0.05). Under 10cm stubble condition, there was a significant positive correlation between the amounts of soil animal individuals and the number of L. chinensis genotype (P<0.05), which supported partly the “resource specialization hypothesis”. The effects of genotypic diversity on soil microbial community composition and structure were significant under no mowing condition (P<0.05).

Effect of biodiversity through planting companion plants on the control of Meloidogyne incognita.

WANG Xiao-ying1, BAI Guang-ying1, WU Lin-lin1, SHAN Shao-jie1, CHEN Wen-quan2, RUAN Wei-bin1*

2016, 35(5): 1233-1239.

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In the study, we selected 12 plant species to evaluate the influence of one, two and four plant species combinations on tomato growth and population suppression of the rootknot nematode, Meloidogyne incognita, and the whitefly, Trialeurodes vaporariorum in a pot trial. The addition of onecompanion plant species resulted in a lower number of M. incognita eggs in Lolium perenne and Mentha haplocalyx pots compared with control pots (without companion plants). Additionally, there was a decline in total number of the nematodes in the other companion plant treatments as well. Furthermore, the number of the T. vaporariorum was significantly lower in the presence of companion plant treatments than in control pots. In general, plant identities have a greater potential to control M. incognita than plant diversity.

Leaf water δ¹⁸O characteristics and impact factors of three plants in Beijing mountainous area.

LOU Yuan-hai, Yu Xin-xiao*, DENG Wen-ping, JIA Guo-dong, LIU zi-qiang

2016, 35(5): 1240-1247.

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Leaf water stable isotopes can indicate material and energy exchange between the inside and outside of the leaf. They can also reflect the climate and ecological information of plant growth. Based on the observed data of the leaf water stable isotope δ¹⁸O variations of Platycladus orientalis, Quercus variabilis and Vitex negundo in Xishan Mountain, Beijing, combined with soil water δ¹⁸O and meteorological observation, this study explored the diurnal and seasonal variations of leaf water δ¹⁸O characteristics and its relationship with meteorological factors. The results showed that, in dry/rainy season, the stem water δ¹⁸O of the three species was relatively stable, and the stem water δ¹⁸O of the three species in rainy season was larger than that in dry season. However, because the enrichment and the variation of the leaf water δ¹⁸O of the three species was greater in dry season than in rainy season, the daily average leaf water δ¹⁸O of the three species was greater in dry season than in rainy season. The slope and intercept between leaf water δ¹⁸O and δD of the three species in dry season were larger than those in rainy season, indicating that RH was an important factor causing the difference of leaf water δ¹⁸O of the three species. The leaf water δ¹⁸O of Q. variabilis and V. negundo was more sensitive to meteorological factors (RH, PAR, air temperature, pressure, VPD) in dry season than in rainy season, while P. orientalis leaf water δ¹⁸O had no significant correlation with these meteorological factors in either dry or rainy season.

Fine root morphology characteristics of Larix principisrupprechtii along an elevation gradient.

HU Rui-zhi, DU Zi-qiang, LIU Shuang, SHI Jian-wei*

2016, 35(5): 1248-1253.

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Mountain altitudinal gradient contains the changes of multiple environmental parameters, and fine roots, functioning as the basis of plants in absorbing water and nutrient, are sensitive to these environmental changes. In this study we investigated the response of fine root morphology to the altitudinal gradient in the Panquangou National Nature Reserve in Shanxi Province, northern China, to improve our understanding of the underground processes of plants in the context of global environmental change. We measured the variations of root morphology, including diameter, root tissue density, specific root length and specific root surface area, among different root orders for Larix principisrupprechtii (distributed in 1800-2700 m above sea level). The data showed that (1) For the same root order, with the elevation increasing, root diameter increased and root tissue density (RTD) decreased, while specific root length (SRL) and specific root surface area (SRA) showed low values at the low and high elevations; (2) At each altitude, root diameter and RTD increased along with the root order increasing, but SRL and SRA declined; (3) The analysis of variance showed that altitude and root order significantly influenced the morphology of fine roots (P < 0.05), and they interacted to exert influence on the root diameter and RTD only (P<0.05). For the first three root orders, root diameter and RTD were closely related with the altitude (P < 0.05). However, for the fourth and fifth root orders, the correlation between altitude and the four morphology characteristics was not significant. These results are important for understanding the mechanism of response of fine roots to future climate change.

Seasonal variation of community structure of crustacean zooplanktons in Lake Jiaoganghu.

XU Mei, WU Fang-yi, LIU Jing-jing, WANG Bian, SUN Qing-ye, ZHOU Zhong-ze*

2016, 35(5): 1254-1262.

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Seasonal variation of crustacean zooplankton community structure in Lake Jiaoganghu was studied from October 2013 to July 2014. The environmental factors affecting the community structure of crustacean zooplanktons were analyzed by CCA method. The results showed that a total of 17 species were recorded, among which 11 species (8 genera) belong to Cladocera and 6 species (5 genera) belong to Copepoda. The dominant species of Cladocera were Diaphanosoma sp., Alona rectangula and Bosmina fatalis. Microcyclops vaticans and Thermocyclops hyalinus dominated the Copepod community. There was a significant seasonal variation in the density and biomass of crustacean zooplanktons in Lake Jiaoganghu. The mean density and biomass of crustacean zooplanktons were (196.30±313.75) ind·L^-1 and (1.80±3.18) mg·L^-1 respectively, and both much higher in spring and summer than in autumn and winter. The maximum density \[(31.47±51.09) ind·L^-1\] and biomass \[(2.82±4.58) mg·L^-1\] of Copepodas community occurred in summer, while the maximum Cladocerans density \[(28.53±55.91) ind·L^-1\] and biomass \[(0.61±0.70) mg·L^-1\] occurred in summer and spring respectively. The mean Shannon diversity index of crustacean zooplanktons was 1.07±0.81, with the maximum value occurring in spring. The result of CCA analysis showed that water temperature, pH value, phytoplankton biomass and nutrient contents were the important factors affecting seasonal variations of crustacean zooplankton community in Lake Jiaoganghu.

Salinity tolerance of fertilized eggs and larva of Eleutheronema tetradactylum.

XIE Mu-jiao1,2, OU You-jun1, WEN Jiu-fu1, LI Jia-er1*, WANG Peng-fei1, ZHOU Hui1,2, LIU Qi-qi1，2

2016, 35(5): 1263-1267.

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This study was conducted to investigate the effects of salinity levels on the sinking, buoyancy, hatching and abnormal rate of fertilized eggs of Eleutheronema tetradactylum under a salinity gradient of 5, 7, 9, 11, 13, 15, 20, 25, 28 (as control), 30, 35, 40, 45. Furthermore, the survival activity index (SAI) of larval E. tetradactylum was observed. The results showed that both fertilized eggs in the stages before the first division and the gastrula sank at salinity below 25, suspended in the central layer when the salinity was 25, and floated at salinity of 28 or more. Fertilized eggs before the first divisions were more sensitive to salinity change than those in the gastrula stage. Survival rate and SAI value of newly hatched larva were significantly impacted by salinity change. Based on hatching rate, abnormal rate of larva and SAI value analysis, it is speculated that the suitable salinity range of E. tetradactylum fertilized egg hatching is 25-35, and the optimum value is 35.

Subfossil chironomid assemblages and the related environmental factors in subalpine mires, western Hubei Province.

CAO Yan-min*

2016, 35(5): 1268-1276.

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Mires are considered to be an important type of wetland ecosystem. The unique environment like its acidic, waterlogged and deoxygenated conditions raises diverse inhabitants that constitute an indispensable component in global biodiversity. In this study, we investigated chironomids in two subalpine mires of Qizimeishan and Erxianyan, western Hubei Province, and attempted to figure out the potential controlling factors on the chironmomids’ composition and distribution. The results revealed that: 1) the chironomid communities were mainly dominated by acidophilic or epiphytic taxa. Tanytarsus pallidicornistype2 and Tribelos sp. were the most abundant taxa in Qizimeishan mire, and Pseudorthocladius sp., Tribelos sp. and Pseudosmittia sp. were dominant taxa in Erxianyan mire; 2) conductivity, calcium concentration and water table depth were the significant environmental factors in shaping chironomid communities. This study was the first report in China about chironomid compositions in mires, and provided important information for further understanding biodiversity in mires.

Classification of Grus monacha’s wintering habitats based on their number and activity time.

DING Wen-hui, LI Xiu-zhen*, JIANG Jun-yan, ZHANG Qian, ZHANG Yun-qing, HUANG Xing, XIE Zuo-lun

2016, 35(5): 1277-1284.

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Chongming Dongtan is an important stopover point and wintering habitat for the nationally protected water bird Grus monacha. Due to the influence of intensive human activities and exotic species Spartina alterniflora, the suitable wintering habitats have changed substantially, which brings serious challenge to the protection of G. monacha and many other species. Four variables were used to analyze the habitat for the G. monacha: cover type, vegetation coverage, tidal flooding depth and distance from the levee. We investigated the influence of the above environmental variables on the activities of G. monacha, and used the number and activity time of crane population as a parameter to quantify the suitability of these variables. We calculated the suitability index of G. monacha’s habitat in Chongming Dongtan, and mapped the spatial distribution of the index values. The results indicated that the suitable, moderately suitable, marginally suitable and unsuitable wintering habitat areas were 697, 469, 282, and 352 hm², respectively. The suitable and unsuitable habitats occupied 38.7% and 19.6% of the total area, respectively. Moderately and marginally suitable habitats covered more than 40% of the total area, which can be improved to become suitable for G. monacha potentially. We provided some suggestions about how to protect the G. moncha population and enlarge the suitable habitat area such as providing food in the moderately and marginally suitable habitats to enlarge the suitable wintering habitat, and take measures to recover the native species Scirpus mariqueter.

Spatial distribution of larch caterpillar and its driving factors.

YU Yue1,2, FANG Lei2, WANG Feng-xia3, MA Wang2,4, TONG Yan-feng1, YANG Jian2*

2016, 35(5): 1285-1293.

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Larch caterpillar (Dendrolimus superans Butler) is one of the most common defoliators in the forests of Great Xing’an Mountains. Modeling the spatial distribution and elucidating its occurrence mechanisms at landscape scales are of high importance for regional prevention and management of this forest pest. In this research, we analyzed the historical larch caterpillar occurrence data observed during 2008-2012 at the stand level across three forestry bureaus of Great Xing’an Mountains. We used generalized linear model (GLM) and maximum entropy model (MaxEnt) to predict spatial distribution of larch caterpillar under the influences of a suite of environmental variables representing site conditions and forest stand structure. We also assessed the marginal effect and relative importance of those environmental variables. The results showed that both GLM and MaxEnt models produced good predictions. Although the spatial distribution patterns of the potential larch caterpillar occurrence probability derived from the two models were similar, there were clear differences in pestprone areas when setting various probability thresholds. Elevation, stand age, soil thickness and larch proportion in a stand were important environmental variables in determining larch caterpillar distribution. Our results indicated that the larch caterpillar might have the highest occurrence probability in the area where the elevation was around 300 m and forest was young or in the middleage group. The occurrence probability tended to be higher in the stands with a thinner soil layer. Larch proportion in a stand exhibited a positive but nonlinear relationship with the pest occurrence probability.

Scale effect of net primary productivity based on remote sensing in arid region.

YANG Hui-jin1, LIU Li-juan1, MA Jin-long1, WANG Jin2, LI Xiao-yu1*

2016, 35(5): 1294-1300.

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Remote sensing is one of widely used data source of landscape analysis with different resolutions. Predominant ground object could be different on various scales. Multiscale analysis has become a necessary method in the field of landscape ecology because a single scale could not describe or explain many environmental problems. The data, which were aggregated by average with different resolutions (30, 150, 330, 660, 990, 1650, 1980 and 3300 m) based on the Landsat 8 remote sensing images with original 30 m resolution of 2013, were input to remote sensing model to simulate multiscale NPP. The results showed that, with scaling up, NPP of crop increased, but NPP of forest, grassland and bare land almost remained unchanged. Average stimulated NPP of 30 m resolution was 5.36% higher than that of 990 m resolution. Upscaling induced the change of mean estimated NPP in Mans River Watershed, producing scale effect, due to land cover change. However, the spatial patterns of NPP in Mans River Watershed were similar on various scales and their characteristics remained unchanged with scaling up.

The division of precipitation change and its regional characteristics in Northeast China during 1961-2014.

GAO Xi-ning1*, JIANG Shan-shan1, WANG Song2, TIAN Lu3, ZHOU Meng-qiao4

2016, 35(5): 1301-1307.

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Northeast China is an important base for food and cash crop production. As one of the sensitive areas to climate change, Northeast China is susceptible to abnormal rainfall, drought and other extreme events under the background of climate change. In order to study the division of precipitation change and its regional characteristics in Northeast China, the monthly precipitation data during 1961-2014 from 87 meteorological stations were used to calculate the percentage of precipitation anomalies, the division of precipitation change was made by using rotated empirical orthogonal function analysis (REOF) method, and the variation trends of precipitation in the whole area and each division region during 1961-2014 were analyzed by using linear trend analysis and 5year moving average analysis method. The results showed that Northeast China could be divided into 4 regions including southeast, central west, north and southwest regions. The annual precipitation anomalies in Northeast China had a slight decline trend, and the climatic trend rate was -4.817 mm·10 a^-1. Each region exhibited a similar decline trend with the whole area. The most obvious decline occurred in southwest region, while the least decline was in north region, with the climatic trend rates of -7.699 and -0.798 mm·10 a^-1, respectively.

Remote-sensing monitoring of urban forest leaf biomass in Shanghai.

WANG Zi-Jun1,SHEN Guang-Rong1,3*, ZHU Yun1, HAN Yu-Jie4,LIU Chun-Jiang2,3, XUE Chun-Yan4

2016, 35(5): 1308-1315.

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Estimation of urban forest leaf biomass at regional scale plays a significant role in understanding plant growth, carbon assimilation processes and forest ecosystems. In this study, an urban forest leaf biomass estimation method which combined regression analysis and spatial analysis in Shanghai, China was explored. Based on the measured data of leaf biomass from June 2011 to June 2012 and a variety of remote sensing data, an analysis of the distribution characteristics of urban forest leaf biomass was also carried out. The results showed that (1) The higher leaf biomass densities concentrated mainly in the urban areas like Jing’an District and the Huangpu District, while suburban localities like Songjiang District and Jinshan District presented lower biomass densities, which were around 4 to 10 and 1 to 6 t·hm^-2, respectively. (2) The density and the amount of urban forest leaf biomass in Shanghai were 2.55 t·hm^-2 and 300.81×10³ t, respectively. The overall leaf biomass was also found to be distributed mainly in the suburban areas with a fraction of 94.16%, whereas the urban areas shared a little fraction of 5.84%. Among the administrative districts of Shanghai, Chongming County and Pudong New District owned the highest and second highest leaf biomass, altogether reaching 34.82% of the total, however, Jing’an District occupied only 0.11%, which was in accordance with its area proportion. (3) The rootmeansquare error (RMSE), mean absolute error (MAE) and mean relative error (MRE) of the regressionIDW model for urban forest leaf biomass in this study were respectively 0.81%, 0.62% and 29.33%, which were decreased by 58.46%, 48.76% and 48.71% respectively than those of the original simple regression model and by 47.74%, 38% and 49.24% respectively than those of the spatial analysis method. The combination of spatial analysis and regression analysis provided a quick, convenient and efficient method for estimating the urban forest leaf biomass and monitoring upscaled forest inventory data at a regional scale.

Ecological footprint and its driving force in Shaanxi Province.

BIAN Zi-hao1,2, ZHAO Yong-hua2,3*, WANG Xiao-feng2,3, AO Yong2,3

2016, 35(5): 1316-1322.

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Ecological footprint is an important evaluating indicator of sustainable development. Based on the latest algorithm and improved model of ecological footprint, ecological footprint was calculated and analyzed in order to understand the dynamic change of ecological deficit in Shaanxi Province from 2002 to 2012. The gray system GM (1, 1) model was used to establish ecological deficit and per capita ecological deficit forecast models for forecasting the future sustainable development of Shaanxi Province. Meanwhile, principal component analysis was used to study the driving force of ecological footprint’s growth. The results showed that ecological footprint kept growing during 2002-2012 in Shaanxi Province, and carbon footprint made the largest contribution to the growth. The current development status of Shaanxi Province was unsustainable according to its stabling biocapacity and increasing ecological deficit. If the development and consumption patterns remained stable, the ecological deficit and per capita ecological deficit would continue to rise in the future in Shaanxi Province. The rapid urbanization was the most important driving force of ecological footprint growth. Thus in the future, for the sustainable development of Shaanxi Province, we need to vigorously develop low carbon economy, save energy, reduce emissions and lower our dependence on fossil fuels.

Hyperspectral characteristics of spring maize and the inversion of soil moisture under drought stress.

LIN Yi1, LI Qian2, WANG Hong-bo3, JI Rui-peng3, FENG Rui3, ZHAO Zi-qi3, ZHANG Kai1, LI Lan1, WEI Nan4, ZHANG Yu-shu3*

2016, 35(5): 1323-1329.

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Using the data observed with ASD FieldSpec Pro FR spectroradiometer based on a trial with various levels of drought stress during different growth periods of maize in Jinzhou, Liaoning Province, the variation characteristics of maize canopy hyperspectral reflectance were investigated and inversion models on soil water content considering spectral parameters were established. The results showed that, after drought stress during the period from seven leaves to jointing, the spectral reflectance within spectral bands of 750 to 1400 nm, the amplitude and the area of red edge decreased and the time of their response to drought stress was shorter, and differed from those under wellwatered condition, while the reflectance within the spectral bands from 350 to 750 nm and from 1400 to 2300 nm demonstrated an increasing trend. As far as inversion methods, the inversion error of soil water content with regression method based on hyperspectral reflectance was smaller than that of first derivative spectra. Moreover, the inversion accuracy of soil water content at the 10 cm depth was higher than that at the depth of 30 cm.

Climatic risk assessment of wheat powdery mildew in China.

ZHANG Lei, GUO An-hong*, WANG Chun-zhi

2016, 35(5): 1330-1337.

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Powdery mildew, as one main disease threatening wheat production, has been increasingly popular in recent years. In this study, climatic risk aspects were assessed to explore the epidemic tendency of wheat powdery mildew in China, by using data of wheat powdery mildew disease from 1961 to 2010 in mainly affected provinces, their yearly wheat planting data, and daily meteorological data from 1961 to 2010 of 392 stations in those provinces. Frequency of differentclass days at decade scale was selected as the climatic hazard index for wheat powdery mildew, and occurrence area ratio of powdery mildew as the vulnerability index. Comprehensive risk index was built by integrating hazard and vulnerability indexes to assess risk development trend in decades. The results showed that the climatic hazard for wheat powdery mildew decreased from south to north and was similar in different decades. Vulnerability for wheat powdery mildew tended to be severe over time, and the climatic hazard had been more severe and its scope had been larger since the 1960s but decreased in 2001-2010. High climatic risk was mainly distributed in west Yunan, Guizhou, east Sichuan, Hunan, Hubei, south Anhui, Jiangsu, Zhejiang and Fujian, where more attention should be paid to take effective measures to reduce the detriment of wheat powdery mildew.

Identification and assessment of landscape character of Haidian District, Beijing.

LIU Wen-ping1, YU Zhen-rong2*

2016, 35(5): 1338-1344.

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Landscape character assessment is a useful tool which can identify regional landscape character, prevent landscape homogenization, and promote landscape protection and development on the background of urbanization in China. According to natural elements and their spatial pattern of a landscape, this study quantitatively identified different landscape character types in Haidian District, Beijing by using a cluster analysis based on GIS and several other technologies. 46 types of thirdgrade landscape classification, 15 types of secondgrade landscape classification and 5 types of secondgrade landscape classification were identified. The spatial distribution characters of 5 firstgrade landscape types were assessed using indicators of landscape division index, patch density and landscape shape index. The results showed that there was an overlapped zone of urban landscape and rural landscape 10-12 km away from the city center. It appeared a landscape mosaic of rural landscape and pastoral landscape when the distance was beyond 12 km from the city center, while a mountain landscape was dominated when the distance was beyond 32 km. Leisurable landscape distributed separately throughout the study area.

Analysis of urban park accessibility in Shenyang City.

SHI Tuo, LI Jun-ying*, LI Ying, YIN Hong-yan

2016, 35(5): 1345-1350.

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Urban park accessibility is an important index, which reflects the service level and the layout reasonability of urban parks. Using the network analysis and simple buffering methods from GIS technique, in combination with the data of roads and population, we evaluated the accessibility of urban parks within the 3rd Ring Road area in Shenyang City, Liaoning Province. The results show that the urban parks’ accessibility and quality of services are low within the 3rd Ring Road area of Shenyang. The accessible area measured by simple buffering is larger than that by network analysis, and their difference is nearly twice when the access time is within fifteen minutes. The accessibility of urban parks in the urban center area is much better than that of those parks in the suburb. The numerical relation of accessible area’s difference is related to the types of urban road network. In checkboard road network, the accessible area calculated using simple buffering is nearly three times larger than that by network analysis when the access time is within fifteen minutes, and the difference decreases gradually with the time increasing. This study can provide theoretical basis for optimizing green space structure.

Mercury emissions from a coal-fired power plant burning high ash content anthracite coal.

TANG Li1,2, LIU Hong-yan1, FENG Xin-bin2, LI Zhong-gen2*, FU Cheng-cheng3, WANG Hao3, CHEN Ji2, WANG Sheng4

2016, 35(5): 1351-1357.

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Coal-fired power plant (CFPP) is one of the most important atmospheric mercury (Hg) sources in China, while studies on the burning anthracite coals of the CFPPs were inadequate. In this study, we investigated the atmospheric Hg emissions and mass balance of a CFPP that burned high ash content anthracite coal in southwestern China. Flue gas was sampled with the Ontario Hydro Method (OHM), and solid samples such as coal, limestone, bottom ash, fly ash, and gypsum were also collected. The CFPP is a pulverized coal (PC) boiler equipped with selective catalytic reduction (SCR), electrostatic precipitator (ESP) and wet flue gas desulfurization (WFGD). The results showed that total Hg content in the flue gas of the final discharging point was 0.60 μg·m^-3, much lower than the national emission limit (30 μg·m^-3). Due to the high ash content in the flue gas, particulate bounded mercury were the main form in flue gas before ESP, hence resulting in a high Hg removal efficiency through ESP. The total Hg removal efficiency for this CFPP was 97.15%, of which, 84.57% was obtained by ESP, 12.58% through WFGD. The Hg emission factor of this CFPP was 3.87 mg Hg·t^-1 coal, which was at lower level among those previously reported. Among the Hg emitted from the CFPP 82.7% was in gaseous elemental form (Hg⁰), 16.6% in gaseous oxidized form (Hg²⁺) and 0.8% in particulate bound form (Hg-P).

Ameliorative effect of cyanidin-3-glucoside on heavy metalinduced oxidative stress in the liver of SD rats.

LI Ye1, LIN Huai1,2, ZHANG Qian-ru2*, BAI Wei-bin3

2016, 35(5): 1358-1363.

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The present study examined the possible protective effect of Cyanidin-3-glucoside (Cy-3-glu) against Cdinduced damage on lipids peroxidation and stress biochemical parameters of rats. SpragueDawley rats were randomly divided into 4 groups of 5 animals each and treated orally with Cd (5 mg·kg^-1), Cy-3-glu (100 and 200 mg·kg^-1) alone or in combination for 5 days. The result showed that the treatment with Cy-3-glu obviously alleviated the body weight loss of rat caused by heavy Cd stress, and the liver, kidney and testis viscera index were significantly or extremely significantly increased with Cy-3-glu dose. Cd exposure induced significant increase in the activities of reactive oxygen species (ROS), lipid per-oxidation levels (MDA) in the exposed groups compared to the control group, and the antioxidant enzymes activities also changed, but cotreatment with Cy-3-glu (200 mg·kg^-1) significantly improved the damage induced by Cd and the SOD enzyme activities were significantly increased. The POD and CAT enzyme activities did not show concentrationresponse relationships. The antioxidant potential in liver was markedly restored with a significant decline in ROS and MDA levels. In conclusion, these results suggest that Cy-3-glu could protect the rat liver against Cd-induced injury by increasing the activities of antioxidant enzymes and reducing oxidative stress.

Thermal comfort assessment and urban thermal environment research: Review and prospective.

WU Zhi-feng1,2, CHEN Li-ding1*

2016, 35(5): 1364-1371.

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Rapid urbanization has caused apparent change in surface energy balance due to large replacement of natural vegetation with artificial surfaces, which leads to the urban heat island (UHI) and deteriorates thermal comfort of urban residents. The outdoor thermal comfort assessment focuses on estimating people’s thermal sensation in outdoor environment by considering meteorological factors and individual activities. The results can be used to identify the high risk area suffering from thermal stress in urban area and the valuable measures to mitigate harmful environment. In this paper, we systemically reviewed the development of thermal comfort theory and introduced indices used in thermal comfort analysis, the scientific basis of these indices and the existing problems. Then, how to improve thermal environment was analyzed from perspectives of street orientation, building layout and arrangement of vegetation and water bodies. Last, the limitations of thermal comfort assessment were discussed, and the perspectives in thermal environmental study were given: (1) to improve the simulation accuracy of outdoor thermal environment evaluation model; (2) to develop uniform standards on field measurements and questionnaire surveys in thermal comfort researches in purpose of improving comparability of different studies; (3) to aware the disparities between thermal comfort levels and urban heat island intensities and take effective mitigation measures according to specific cases; (4) to consider thermal comfort by integrating temporal scale and spatial scale, and propose overall and feasible strategies to improve urban thermal environment.

Advances in arbuscular mycorrhizal fungi alleviating continuous cropping obstacles.

LI Liang1,2, CAI Bai-yan1,2*

2016, 35(5): 1372-1377.

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Continuous cropping for many years can lead to reductions in crop yields and agricultural product quality, which severely restricts the sustainable development of agriculture. This is a leading issue in agricultural cultivation in China. Arbuscular mycorrhizae (AM) fungi can improve the continuous cropping soil environment, enhance the capacity of plant uptake of nutrients and water, and improve plant resistance to soilborne diseases as a result of continuous cropping. Recently, scientists working in ecology and agricultural production have explored the effect of AM fungi in alleviating the challenges posed by continuous cropping. In this review, we summarize the results of a wide range of research into AM fungi, including improving the continuous cropping soil environment, promoting the uptake of hostplants of nutrients and water, improving the salt tolerance of host plants and their competitiveness against pathogenic bacteria, and disease resistance to antagonistic bacteria. Furthermore, the role of AM fungi in the induction of protective enzyme expression and the effects on secondary metabolite generation, amongst other effects, are also discussed in this context. Overall, we aim to provide a theoretical basis for the future development of technology that utilizes AM fungi in solving continuous cropping obstacles.

Identification and fermentation optimization of a biosurfactant-producing strain isolated from seawater.

DU Jin, HAO Jian-an, ZHANG Xiao-qing, WANG Jian-yan, ZHANG Ai-jun, WANG Jing*

2016, 35(5): 1378-1385.

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This experiment studied a biosurfactantproducing bacterial strain isolated from seawater, designated as dhs-330. Phylogenetic analysis of the homoeologous 16S rDNA gene sequences, the optimization of culture conditions of carbon source, nitrogen source, pH and temperature, MALDITOF Mass Spectrometry identification of the products, and antimicrobial activity assay were carried out. The 16S rDNA sequence of Bacillus sp. dhs330 shared a 99% sequence similarity with Bacillus mojavensis. Bacillus sp. dhs-330 decreased the surface tension of culture medium from 70 mN·m^-1 to 27 mN·m^-1. It could grow well with high production of biosurfactants under the following conditions: glycerol as carbon source, yeast extract as organic nitrogen source, urea as inorganic nitrogen source, initial pH 6.5-7.0 and 30-35 ℃. Its principal products were blendbiosurfactants of lipopeptide and glycolipid, which showed antimicrobial activity against marine fouling bacteria Bacillus pumilus dhs04. Strain dhs330 presented a potential application in blend-biosurfactant production and anti-fouling technology.

Methylation of MLH1 promoter in Arabidopsis thaliana as a biomarker of cadmium stress.

HE Lei1,2, WANG He-tong2, SONG Jie1,2, CUI Wei-na2,3, CAO Xia2, HUI Xiu-juan1, TAI Pei-dong2, YANG Yue-suo4, LIU Wan2*

2016, 35(5): 1386-1393.

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Using bisulfite DNA sequencing technique, this study investigated the methylation patterns of 71 cytosine residues including 16 CpG sites, 6 CHG sites (H as C, A or T) and 49 CHH sites within the region 391 bp between nucleotides -346 to +42 in MLH1 promoter region in Arabidopsis plantlets exposed to 0-5.0 mg·L^-1 cadmium (Cd) for 21 days. The methylation percentages of CpG, CHH and CHG sites were 44.8%, 40.5% and 52.0%, respectively, in the control. With the increasing Cd level, the hyper and hypomethylated cytosine residues, and the methylation percentages of those residues for CpG, CHG and CHH sites were increased in the Cdtreated seedlings, and were higher at CpG and CHH sites than in the controls except for CHG sites. Among 71 cytosines in MLH1 promoter regions, methylation polymorphism of CpG6, CpG9, CHH44 and CHG4 sites was much more sensitive to Cd stress than other cytosine residues, and the effect was dosedependent. The percentage of hypermethylation change for CpG9 site was 20.0%, while the percentages of hypomethylation change for CpG6, CHH44 and CHG4 sites were 12.0%, 20.0% and 20.0%, respectively, in the Cdexpoesd seedlings at Cd level of 0.25 mg·L^-1. The presence of significant methylation polymorphism of cytocine residues for the above four hot spots in MLH1 promoter of Cdtreated seedlings, prior to the onset of leaf number, fresh mass and chlorophyll content of shoots, suggests that methylation polymorphisms of these hot loci are the most sensitive biomarkers for early diagnosis and risk assessment of genotoxic effects of Cd pollution.

Extraction of vegetation coverage in arid regions using multiscale remote sensing data synergistically.

2016, 35(5): 1394-1402.

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The acquisition of pure vegetation pixel is a necessary step in the extraction of vegetation coverage. However, the vegetation distributes sparsely in arid regions and it is difficult to extract the pure vegetation pixel using low spatial resolution remote sensing data. Consequently, the vegetation coverage extraction accuracy is low. This paper proposed a new method for vegetation coverage retrieval in arid regions using multiscale remote sensing data synergistically. This method used Landsat-8 OLI data, which has a spatial resolution of 30 m, to determine the pure vegetation pixel. In order to eliminate the difference of NDVI from both MODIS and OLI data, induced by the spectral difference of these two sensors, a spectrum transformation procedure was conducted by using ground measured vegetation and soil spectra. A typical arid area located at Fukang City, Xinjiang was selected as the study area to conduct the inversion experiment of vegetation coverage based on this method. In order to verify the accuracy of the new method, validation using the very high resolution aerial image was conducted. The validation showed that the coefficient of determination between the retrieved value and measured value was 0.75, and the RMSE was 0.10. Thus, the method can effectively improve the accuracy of vegetation coverage retrieval and provide a new way to study the ecological environment in arid areas by using low resolution data.

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