Table of Content

18 June 2017, Volume 28 Issue 6

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Effects of drying-rewetting on leaf litter decomposition and nutrient releases in forest plantations in Horqin Sandy Land, China

LI Jin-tao, SUN Xue-kai, HU Ya-lin, ZHAO Shan-yu, ZENG De-hui

2017, 28(6):  1743-1752.  doi:10.13287/j.1001-9332.201706.033

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Soil drying-rewetting is a common phenomenon in arid and semi-arid regions. Under the background of global climate change, it is predicted that the intensity of soil drying-rewetting cycle in Horqin Sandy Land will be further strengthened in the future. In this study, we conducted an in-situ soil column incubation experiment for 180 days to investigate the effects of soil drying-rewetting on leaf litter decomposition and nutrient releases of Populus simonii and Pinus sylvestris var. mongo-lica in Horqin Sandy Land. There were three treatments: Constantly moist treatment (CM, 60% water holding capacity during whole incubation period), mild drying-rewetting treatment (DW₁, gra-dual drought for 10 days plus 60% WHC for 20 days) and heavy drying-rewetting treatment (DW₂, gradual drought for 20 days plus 60% WHC for 10 days). To evaluate their delayed effects, leaf litter in all three treatments were incubated for 60 days under same and constant humid condition (60% WHC) after four cycles of soil drying-rewetting. The responses of litter decomposition to soil drying-rewetting cycles and nutrient releases of P. simonii and P. sylvestris var. mongolica were similar during the drying and rewetting period. Litter mass loss and the release of C, lignin and total phenol were decreased by 17.4%, 23.8%, 35.2% and 32.7% in DW₂ treatment compared with CM treatment. There was no significant difference in release of leaf litter N or P among the drying-rewetting treatments. There were consistent changes of litter mass loss and nutrient releases among the treatments at the end of drying-rewetting and delayed incubation period. However, litter decomposition rate and litter C and lignin release rates were increased in DW₂ treatment compared with CM treatment during the delayed incubation period, indicating a short-term delayed effect.

Impacts of warming and nitrogen addition on organic fraction release in fresh litter of Larix potaninii in alpine zone of the western Sichuan Province, China

CHEN Yue-xi, CHEN Bei, SUN Hui, MA Li-hong, SHEN Dan-jie, LIU Yan-yang

2017, 28(6):  1753-1760.  doi:10.13287/j.1001-9332.201706.040

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The decomposition dynamics of organic components in fresh litter of Larix potaninii were monitored by in situ litter-bag incubation under four treatments, i.e., field condition (CK), nitrogen addition (AN, 2 g N·m^-2), warming by top-open chamber (OTC), nitrogen addition with warming by top-open chamber (OTC+AN), from November to next September. Decomposition of water-soluble sugar, water-soluble phenol and total polyphenol were stimulated significantly under the treatment OTC, AN and OTC+AN during the first four months compared with the CK, but the difference of these components release narrowed with the extension of incubation time. Compared with CK, releases of dichloromethane-extractable fraction, acid soluble carbohydrates, acid soluble lignin, and acid insoluble lignin, were inhibited significantly under OTC, AN, and OTC+AN treatments, and the significance of inhibitory effect under the treatments was: OTC > OTC+AN > AN. Especially, in the treatment of OTC, half-life of dichloromethane-extractable fraction and acid inso-luble lignin in fresh litter were doubled, and that of hot-water soluble component was prolonged by more than 50% compared with CK. Half-life of water-soluble sugar, water-soluble phenol, total polyphenol, acid-soluble carbohydrate and acid-soluble lignin in fresh litter were respectively 182, 159, 127, 154 and 190 d in CK, and these components seem to be easily mineralized organic fraction. Meanwhile, half-life of hot-water soluble components, dichloromethane-extractable fraction, and acid insoluble lignin was 209, 302 and 318 d, respectively, indicating these fractions recalcitrant to decomposing in the fresh litter. Decomposition of all components in L. potaninii litter occurred in cold season from November to next March, which suggested that cold season was the most important period for litter decay in the alpine conifer. Generally it was assumed that microorganisms were inactive and decomposition of organic matters was slow in alpine soil during harsh winter, while the results of fresh litter incubation in situ showed that all components decomposed very fast during the period. Therefore, in alpine treeline, nitrogen deposition and warming would inhibit rather than promote decomposition of fresh litter, which would be conducive to carbon sequestration for the alpine soil ecosystem.

Spatial heterogeneity of soil salinization and its influencing factors in the typical region of the Mu Us Desert-Loess Plateau transitional zone, Northwest China

ZHAO Xuan, HAO Qi-li, SUN Ying-ying

2017, 28(6):  1761-1768.  doi:10.13287/j.1001-9332.201706.034

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Studies on the spatial heterogeneity of saline soil in the Mu Us Desert-Loess Plateau transition zone are meaningful for understanding the mechanisms of land desertification. Taking the Mu Us Desert-Loess Plateau transition zone as the study subject, its spatial heterogeneity of pH, electrical conductivity (EC) and total salt content were analyzed by using on-site sampling followed with indoor analysis, classical statistical and geostatistical analysis. The results indicated that: 1) The average values of pH, EC and total salt content were 8.44, 5.13 mS·cm^-1 and 21.66 g·kg^-1, respectively, and the coefficient of variation ranged from 6.9% to 73.3%. The pH was weakly variable, while EC and total salt content were moderately variable. 2) Results of semivariogram analysis showed that the most fitting model for spatial variability of all three indexes was spherical model. The C₀/(C₀+C) ratios of three indexes ranged from 8.6% to 14.3%, which suggested the spatial variability of all indexes had a strong spatial autocorrelation, and the structural factors played a more important role. The variation range decreased in order of pH <total salt < EC. The Kriging interpolation showed that pH, EC and total salt content distributed in a striped pattern with good continuity. The pH value increased with increasing terrain slope, while EC and total salt content decreased. 3) In terms of vertical distribution, the salt aggregated on surface in the area with severe salinization. In the area with light salinization, the vertical distribution of salinity was firstly decreased and then increased. In general, the heterogeneity of soil salinization in the Mu Us Desert-Loess Plateau transition zone was influenced by climate, landscape, plant distribution, especially affected by geological conditions, topography and hydrogeological conditions. This study provided a theoretical basis for future land engineering and ecosystem restoration programs.

Temporal and spatial variations of extreme climatic events in Songnen Grassland, Northeast China during 1960-2014

MA Qi-yun, ZHANG Ji-quan, LAI Quan, ZHANG Feng, DONG Zhen-hua, A Lu-si

2017, 28(6):  1769-1778.  doi:10.13287/j.1001-9332.201706.002

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Fourteen extreme climatic indices related with main regional meteorological disasters and vegetation growth were calculated based on daily data from 13 meteorological stations during 1960-2014 in Songnen Grassland, Northeast China. Then, the variation trend and the spatial and temporal patterns of climatic extreme events were analyzed by using regression analysis, break trend analy-sis, Mann-Kendall test, Sen’s slope estimator and moving t-test method. The results indicated that summer days (SU25), warm days (TX90P), warm nights (TN90P) and warm spell duration (WSDI) representing extremely high temperatures showed significant increasing trends (P<0.05). Meanwhile, frost days (FD0), cold days (TX10P), cold nights (TN10P) and cold spell duration indicator (CSDI) representing extremely low temperatures showed obviously decreasing trends. The magnitudes of changes in cold indices (FD0, TX10P, TN10P and CSDI) were clearly greater than those of warm indices (SU25, TX90P, TN90P and WSDI), and that changes in night indices were larger than those of day indices. Regional climate warming trend was obvious from 1970 to 2009, and the most occurrences of the abrupt changes in these indices were identified in this period. The extreme precipitation indices did not show obvious trend, in general, SDII and CDD experienced a slightly decreasing trend while RX5D, R95P, PRCPTOT and CWD witnessed a mildly increasing trend. It may be concluded that regional climate changed towards warming and slightly wetting in Songnen Grassland. The most sensitive region for extreme temperature was distributed in the south and north region. Additionally, the extreme temperature indices showed clearly spatial difference between the south and the north. As for the spatial variations of extreme precipitation indices, the climate could be characterized by becoming wetter in northern region, and getting drier in southern region, especially in southwestern region with a high drought risk.

Effects of naphthalene on soil respiration, nutrients and enzyme activities in the subalpine forest of western Sichuan, China

YANG Fan, YANG Wan-qin, WU Fu-zhong, WANG Hui, LAN Li-ying, LIU Yu-wei, GUO Cai-hong, TAN Bo

2017, 28(6):  1779-1785.  doi:10.13287/j.1001-9332.201706.031

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As a biocide to reduce soil and litter faunal populations in field experiments, naphthalene has been widely used in the study of ecological functions of soil fauna, but the non-target effects of naphthalene bring about enormous uncertainty to its application. In order to understand whether there were non-target effects of naphthalene in subalpine forest soil, soil in the subalpine forests of west Qinghai-Tibet Plateau was taken as study object. The short-term responses of soil respiration rate, nutrient content and enzyme activity to naphthalene were studied in microcosms. The results showed that soil respiration rate was significantly suppressed by application of naphthalene within 0-10 days, and then showed a significant promotion effect. Naphthalene significantly affected the dynamics of soil NH₄⁺-N and NO₃^--N contents. With application of naphthalene, the highest contents of NH₄⁺-N and NO₃^--N occurred at the 3rd and 7th day, respectively. But they were observed at the 45th and 52nd day with no-naphthalene, respectively. Moreover, soil dissolved carbon content in the naphthalene microcosms showed a sharp increase and then decrease dynamic at the 3rd day, while small change was detected in the no-naphthalene microcosms. Dissolved nitrogen content in both the naphthalene and no-naphthalene microcosms showed an increase at first and then decreased subsequently during the study period. Similar dynamics were found for the soil enzyme activities in both the naphthalene and no-naphthalene microcosms. The highest activities of urease, nitrate reductase and nitrite reductase in both the naphthalene and no-naphthalene microcosms were at the 45th, 38th and 10th day, respectively. In addition, the interaction of naphthalene treatment and sampling time had significant effects on soil respiration rate, the contents of NH₄⁺-N, NO₃^--N and dissolved nitrogen, but had no significant effects on soil dissolved carbon content, and the activities of invertase, nitrate reductase and nitrite reductase. In a short time, the non-target effect of naphthalene as a biocide to reduce soil fauna abundance might have an important influence on the soil nitrogen cycling in subalpine forest of western Sichuan.

Effects of snow removal on soil labile nitrogen in a subalpine spruce forest of western Sichuan, China

LI Zhi-jie, YANG Wan-qin, HE Ruo-yang, ZHUANG Li-yan, YANG Kai-jun, LIU Qun, LI Ting-ting, XU Zhen-feng

2017, 28(6):  1786-1792.  doi:10.13287/j.1001-9332.201706.027

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Warming-induced decrease in seasonal snow cover has a great potential to affect soil nitrogen cycle in alpine cold forest ecosystems. In this study, a wooden-shelter method was used to remove the snow accumulation. Soil nitrogen pools and mineralization rates in the snow removal and control plots were measured synchronously in three critical periods (early snow cover, deep snow cover and snow cover melting) in a subalpine spruce forest of western Sichuan, China. Seasonal snow cover kept soil from cold air temperature. Snow removal decreased average and minimum soil temperatures (5 cm) by 0.33 and 1.17 ℃, respectively. In addition, snow removal caused a positive effect on soil frost depth and freeze-thaw cycle. There was a significant dynamic in soil labile nitrogen pool among different periods. Snow removal on average increased NH₄⁺-N, NO₃^--N and dissolved organic nitrogen (DON) contents by 38.6%, 23.5% and 57.3%, respectively, over the winter. Moreover, snow removal increased soil net nitrification and mineralization rates in the snow co-ver melting period. Overall, warming-induced decrease in snow cover could stimulate winter soil nitrogen cycle of subalpine forests.

Ecological stoichiometry of leaf and litter of herbaceous plants in loess hilly and gully regions, China

LIU Yang, ZENG Quan-chao, AN Shao-shan, LI Xin, HUANG Yi-mei

2017, 28(6):  1793-1800.  doi:10.13287/j.1001-9332.201706.036

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This study was conducted in the forest, forest-steppe and steppe vegetation zones along the Yanhe River Basin, where the leaf and litter samples from four dominant herbaceous plants including Lespedeza davurica, Stipa bungeana, Artemisia sacrorum, Artemisia giraldii were taken. By measuring the concentrations of carbon (C), nitrogen (N), phosphorus (P) and potassium (K), we measured the concentrations and their ratios to explore the limit and resorption of nutrient in the herbaceous plants. The results showed that the leaf N/P of four herbaceous plants was all lower than 14, suggesting their growth was mainly limited by N content. Except for L. davurica, the mean nutrient resorption efficiency of K, N and P in the other three plants was 79.9%, 48.7% and 32.5%, respectively. The higher nutrient resorption efficiency and K concentration in the leaf were beneficial for soil water competition of A. sacrorum and A. giraldii. The litter C/N in A. sacrorum was significantly lower than that in S. bungeana and A. giraldii, which was easy to decompose to benefit the nutrient recycling. This resulted in the wide distribution of A. sacrorum in the three vegetation areas.

Water use strategy of Tamarix chinensis during a drought year in the coastal wetlands of the Yellow River Delta, China

WANG Ping, LIU Jing-tao, ZHU Jin-fang, FU Zhan-yong, SUN Jing-kuan

2017, 28(6):  1801-1807.  doi:10.13287/j.1001-9332.201706.018

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Tamarix chinensis, the dominant species of plant communities in the coastal wetlands of the Yellow River Delta, was selected to study the water use strategy of coastal plants at different habitats during a drought year. The δ¹⁸O values for xylem water of T. chinensis were analyzed. Potential contributions by different water sources to T. chinensis were estimated using the IsoSource model. The contributions were analyzed to reveal the adaptation mechanism of T. chinensis to water stress at different habitats. The results showed that the main water sources for T. chinensis during a drought year were soil water and groundwater rather than precipitation. However, the water use strategies of T. chinensis changed significantly with different micro-topographies. For dune crests, 72.6%-95.4% water of T. chinensis came from deeper soil water (40-100 cm) and groundwater. However, near the high tide line, T. chinensis absorbed 40.7%-97.3% of the water from the upper soil (0-40 cm) to avoid the salt stress caused by sea water and shallow groundwater. This provided T. chinensis with a competitive advantage related to water consumption and improved its water use efficiency in the coastal ecosystem, which led to mono-dominant shrub community of T. chinensis in this area.

Vegetation spatial and temporal dynamic characteristics based on NDVI time series trajectories in grassland opencast coal mining

JIA Duo, WANG Cang-jiao, MU Shou-guo, ZHAO Hua

2017, 28(6):  1808-1816.  doi:10.13287/j.1001-9332.201706.035

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The spatiotemporal dynamic patterns of vegetation in mining area are still unclear. This study utilized time series trajectory segmentation algorithm to fit Landsat NDVI time series which generated from fusion images at the most prosperous period of growth based on ESTARFM algorithm. Combining with the shape features of the fitted trajectory, this paper extracted five vegetation dynamic patterns including pre-disturbance type, continuous disturbance type, stabilization after disturbance type, stabilization between disturbance and recovery type, and recovery after disturbance type. The result indicated that recovery after disturbance type was the dominant vegetation change pattern among the five types of vegetation dynamic pattern, which accounted for 55.2% of the total number of pixels. The follows were stabilization after disturbance type and continuous disturbance type, accounting for 25.6% and 11.0%, respectively. The pre-disturbance type and stabilization between disturbance and recovery type accounted for 3.5% and 4.7%, respectively. Vegetation disturbance mainly occurred from 2004 to 2009 in Shengli mining area. The onset time of stable state was 2008 and the spatial locations mainlydistributed in open-pit stope and waste dump. The reco-very state mainly started since the year of 2008 and 2010, while the areas were small and mainly distributed at the periphery of open-pit stope and waste dump. Duration of disturbance was mainly 1 year. The duration of stable period usually sustained 7 years. The duration of recovery state of the type of stabilization between disturbances continued 2 to 5 years, while the type of recovery after disturbance often sustained 8 years.

Spatial distribution and spatial association of Potentilla fruticosa populations on different slope aspects in subalpine meadow

LIU Min-xia

2017, 28(6):  1817-1823.  doi:10.13287/j.1001-9332.201706.037

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The adaptation strategies of plant populations under different disturbance conditions could be reflected by the distribution pattern and correlation. Potentilla fruticosais the dominant species in alpine meadow community in south of Gansu Province, China. Based on the field investigation, P. fruticosa population spatial distribution pattern and its correlation were studied by using Ripley K function of spatial point pattern analysis. The results showed that the distribution of P. fruticosa population had significant differences on different aspects, and its species richness, diversity index and coverage showed a decreasing trend from north to south slope. The class Ⅰ and Ⅱ individuals of P. fruticosa population significantly aggregated at small scale in north and west slopes, and P. fruticosa clump intensity was gradually weakened with the increase of age and space scale, and finally tended to a random distribution. On south slope, the distribution patterns of all levels of P. fruticosa individuals were dominated by random distribution due to the inhibition of the habitat conditions and interspecific competition. On different slope aspects, P. fruticosa populations between class Ⅰ and Ⅱ individuals showed a negative correlation at certain scale, but the correlation degree decreased with increasing scale. The relationship between the class Ⅲ and Ⅳ individuals and the class Ⅰ and Ⅱ individuals had negative correlation significantly. There was no significant relationship among the large individuals, indicating that the individuals with similar age was spatially independent, which was conducive to the full use of environmental resources.

Evaluation and selection of species diversity index under grazing disturbance in alpine mea-dow

NIU Yu-jie, YANG Si-wei, WANG Gui-zhen, LIU Li, HUA Li-min

2017, 28(6):  1824-1832.  doi:10.13287/j.1001-9332.201706.026

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The research selected the plots of six grazing intensities in an alpine meadow in north-eastern Tibet Plateau in four years (2012-2015) and studied the relation between ten species diversity indexes, including two measured indexes (Richness and Abundance) in field and two indexes of each dominance, evenness, richness, integrated indexes, and grazing intensity as well as grazing time aiming at scientific selection of biodiversity index under grazing disturbance. The results indicated that the abundance was a better index than importance value to calculate biodiversity level because it was more sensitive to grazing disturbance. Dominance indexes, including Berger-Parker and Dominance, were not sensitive to grazing intensity and grazing time because they could not clarify the effect of grazing disturbance on dominant species in plant community. Evenness indexes, including Equitability and Evenness, had not relation with grazing intensity, however, the evenness index had a negative correlation with grazing time and it was not influenced by occasional species as well as the variation coefficient of species abundance. Hereby, the evenness index could be chosen for studying evenness change at temporal scale. Richness indexes, including Menhinick and Margalef, had no relation with grazing time, however, the Margalef index had a positive correlation with grazing intensity and the index was not influenced by occasional species. Integrated index, including Shannon and Simpson indexes, had no relation with grazing intensity, however, the Shannon index had a significant positive correlation with species richness and abundance and the index was not influenced by occasional species, and it significantly increased along grazing time. Hereby, Shannon index could be used as an index of studying plant species diversity in long-term. In ten diversity indexes, only the measured indexes in field, including richness and abundance, were signifi-cantly negatively correlated with grazing intensity, and positively correlated with grazing time, and the two indexes were not influenced by occasional species. Hereby, the combination of species richness and abundance mea-sured in field could be considered as the most important indexes for studying plant species diversity under grazing disturbance. Besides, the selection of biodiversity indexes must consider the spatial-temporal feature of grazing, diversity components and research purpose.

Predicting the potential distribution of dominant species of the coastal wetland in the Yellow River Delta, China using MaxEnt model

ZONG Min, HAN Guang-xuan, LI Yun-zhao, WANG Guang-zhen, WANG An-dong, YANG Xian-ji

2017, 28(6):  1833-1842.  doi:10.13287/j.1001-9332.201706.017

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Soil and vegetation community were investigated using the method of kilometer grid sampling. In addition, using the maximum entropy (MaxEnt) and the GIS spatial analysis technique, the potential distribution of dominant species in the Yellow River Delta and their major environmental variables and ecological parameters were quantitatively analyzed. The results showed that the dominant species of the coastal wetland were Tamarix chinensis, Phragmites australis and Suaeda salsa in the Yellow River Delta. Among the environmental variables, six variables were significant contributors to the potential distribution model of T. chinensis: NO₃^--N, salt, slope, Mg, altitude and NH₄⁺-N. The environmental variables influencing the distribution of P. australis were NO₃^--N, salt, TP, pH, altitude and NH₄⁺-N. NO₃^--N, salt and NH₄⁺-N were the significant factors determining the potential distribution of S. salsa. The probability of presence of dominant species of the coastal wetland in the Yellow River Delta was positively correlated with salt, but it was negatively correlated with the other major environmental variables. The model predicted that the core potential distribution of dominant species in the Yellow River Delta was mainly in the coastal areas. In addition, P. australis had a wider range of distribution, compared with T. chinensis and S. salsa.

Distribution pattern of riparian invasive plants in Luanhe Basin, North China and its relationship with environment

REN Ying, HE Ping, XU Jie, JIA Jiao

2017, 28(6):  1843-1850.  doi:10.13287/j.1001-9332.201706.020

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In this study, the invasive plant species from the riparian vegetation in 56 sampling sites of Luanhe Basin were identified, and the correlations between their composition, spatial distribution and environmental factors were explored. In the basin, a total of 26 invasive species were registered, which belonged to 19 genera and 12 families, and 73.1% of them were annual plants. Asteraceae and Amaranthaceae were the two dominant families with the most invasive species, attributing to 50% of the total invasive species. Amaranthus retroflexus, Bidens frondosa and Chenopodium serotinum appeared with the highest frequencies. The number of invasive species and the invasive intensity at each site were significantly negatively correlated with the altitude. The distribution of invasive plants was significantly influenced by the intensity of human activities. The invasive plants were mainly distributed in the plain area, shallow mountainous area with many reservoirs, and the mountainous area with developed tourism around Chengde City, meanwhile, only few species with broad ecological amplitude existed in the plateau area. In general, species with higher invasive grades were mainly distributed in low and medium altitude areas below 400 m. Except for A. retroflexus, no high-grade invasive plants were discovered in high altitude area so far.

Individual tree diameter increment model for natural Betula platyphylla forests based on meteorological factors

ZHANG Hai-ping, LI Feng-ri, DONG Li-hu, LIU Qiang

2017, 28(6):  1851-1859.  doi:10.13287/j.1001-9332.201706.009

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Based on the 212 re-measured permanent plots for natural Betula platyphylla fore-sts in Daxing’an Mountains and Xiaoxing’an Mountains and 30 meteorological stations data, an individual tree growth model based on meteorological factors was constructed. The differences of stand and meteorological factors between Daxing’an Mountains and Xiaoxing’an Mountains were analyzed and the diameter increment model including the regional effects was developed by dummy variable approach. The results showed that the minimum temperature (T_{g min}) and mean precipitation (P_{g m}) in growing season were the main meteorological factors which affected the diameter increment in the two study areas. T_{g min} and P_{g m} were positively correlated with the diameter increment, but the influence strength of T_{g min} was obviously different between the two research areas. The adjusted coefficient of determination (R_a²) of the diameter increment model with meteorological factors was 0.56 and had an 11% increase compared to the one without meteorological factors. It was concluded that meteorological factors could well explain the diameter increment of B. platyphylla. R_a² of the model with regional effects was 0.59, and increased by 18% compared to the one without regional effects, and effectively solved the incompatible problem of parameters between the two research areas. The validation results showed that the individual tree diameter growth model with regional effect had the best prediction accuracy in estimating the diameter increment of B. platyphylla. The mean error, mean absolute error, mean error percent and mean prediction error percent were 0.0086, 0.4476, 5.8% and 20.0%, respectively. Overall, dummy variable model of individual tree diameter increment based on meteorological factors could well describe the diameter increment process of natural B. platyphylla in Daxing’an Mountains and Xiaoxing’an Mountains.

Effects of canopy density on the functional group of soil macro fauna in Pinus massoniana plantations

ZHOU Hong-yang, ZHANG Dan-ju, ZHANG Jie, ZHAO Yan-bo, ZHAO Bo, WEI Da-ping, ZHANG Jian

2017, 28(6):  1860-1868.  doi:10.13287/j.1001-9332.201706.029

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In order to understand the effects of canopy density on the functional group characteristics of soil macrofauna in Pinus massoniana plantations, we divided the captured soil fauna into five types including xylophages, predators, saprophages, omnivores and fungal feeders. The results showed that 1) Saprozoic feeders had the highest percentage of total individuals, and the omnivores and xylophages occupied higher percentages of total taxa. 2) The individual and group number of the predators, and the group number of xylophages did not change significantly under 0.5-0.6 and then decreased significantly under 0.6-0.9 canopy density. 3) With the increasing canopy density, the individual an dgroup number of predators in litter layer decreased significantly, the saprozoic individual number in 5-10 cm soil layer represented irregular trends. The individual number of xylophage increased with the depth of soil, and the group number in litter layer, the individual and group number in 5-10 cm soil layer decreased significantly. 4) Pielou evenness of xylophage had no significant changes with the canopy density, all the other diversity index of xylophage and saprophage were various with the increasing canopy density. The predatory Simpson index was stable under 0.5-0.8, and then decreased significantly under 0.8-0.9 canopy density. 5) The CCA (canonical correlation analysis) indicated that soil bulk density and moisture content were the main environmental factors affecting functional groups of soil macro fauna. Moisture content greatly impacted on the number of saprophagous individuals. But xylophage and predators were mostly affected by soil bulk density, and the predatory Simpson index was mainly affected by soil pH value and total phosphorus. Our research indicated that the structure of soil macro faunal functional group under 0.7 canopy density was comparatively stable, which would facilitate the maintenance of soil fertility and ecological function in Pinus massoniana plantation.

Effects of grazing and mowing on macrofauna communities in a typical steppe of Inner Mongolia, China

LIU Xia, ZHAO Dong, CHENG Jian-wei, CHEN Hai-yan, LIU Xin-min, BAOYIN Taogetao, LI Frank Yonghong

2017, 28(6):  1869-1878.  doi:10.13287/j.1001-9332.201706.025

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The dynamic features of the ecosystem components under different human activities are fundamental for understanding the ecosystem change mechanisms and developing sustainable mana-gement system. For the vast temperate steppe ecosystems in northern China, there existed many studies on the effects of animal grazing and mowing on plant and soil microbial communities, but not the soil fauna communities. We investigated the soil macrofauna communities of a typical Inner Mongolia steppe grassland under 6 utilization treatments (1 full season grazing, 3 different seasonal grazing, 1 autumn mowing and 1 control of no grazing or mowing). The investigation was conducted in spring, summer and autumn after 3-year’s grazing or mowing treatments. We collected 597 soil animals, which belonged to 2 phyla, 4 orders, 11 classes, and 49 groups. The individual density, biomass and diversity indices of soil macrofauna community significantly decreased under the full season grazing, whereas the effects of mowing on soil macrofauna were relatively mild, with the individual density, biomass and diversity indices of soil macrofauna community even showing an increasing trend. The seasonal grazing in summer and autumn had the least negative effects on the individual density, biomass and diversity indices of soil macrofauna community among three seasonal grazing treatments. The results suggested that mowing might facilitate the restoration of soil macrofauna community for degraded steppe grassland, and the seasonal grazing in summer and autumn had the least negative effects on soil macrofauna communities, which was possibly the best grazing practice for a sustainable grassland use.

Spatio-temporal distribution of carabids and spiders between semi-natural field margin and the adjacent crop fields in agricultural landscape

ZHANG Xu-zhu, HAN Yin , YU Zhen-rong, LIU Yun-hui

2017, 28(6):  1879-1888.  doi:10.13287/j.1001-9332.201706.030

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This study was conducted before and after harvesting of wheat and maize in a typical agricultural landscape of the North China Plain. We investigated the diversity of two important natural enemy groups, carabids and spiders, using pitfall traps at crop field margin with different vegetation structures and their neighboring crop field. Throughout the comparison of the spatial and temporal distribution of the diversity of carabids and spiders in field margin and neighboring field, and the investigation of the relationship between arthropod communities and vegetation structure, this study aimed to understand the role of semi-natural field margin in biodiversity conservation of different natural enemy taxa. Results showed that the abundance of spiders was significantly higher in field margin than in neighboring fields over the entire period. No significant difference of the diversity of carabids in field margin and crop field was observed, but the community composition was different. Number of spider families increased in field margin but deceased in crop field after harvesting, indicating a migration activity between field and field margin. Vegetation structure in the field margin had different association with carabids than with spiders, with diversity of dominant carabid species positively associated with herb coverage and negatively with wood coverage, while the diversity of spider family Linyphiidae was positively associated with herb coverage only. Semi-natural habitat benefited the conservation of the diversity of arthropod natural enemies in crop field via promoting their dispersal to crop field, while such impacts differed from different vegetation structures and varied from target beneficial natural enemy communities. Future studies should focus on in-depth understanding of the food and habitat source requirement of different natural enemy taxa, and hence to design suitable semi-natural habitats to maintain a high diversity of natural enemy communities.

Effect of nitrogen management modes on grain yield, nitrogen use efficiency and light use efficiency of wheat

WU Xiao-li, LI Chao-su, TANG Yong-lu, LIU Yu-bin, LI Bo-qun, FAN Gao-qiong, XIONG Tao

2017, 28(6):  1889-1898.  doi:10.13287/j.1001-9332.201706.008

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A nitrogen management experiment with three nitrogen levels (0, 120, and 180 kg·hm^-2, namely N₀, N₁₂₀, N₁₈₀) and three nitrogen allocation modes (N_A: base fertilizer 100%; N_B: base fertilizer 70% + seedling fertilizer 30%; N_C: base fertilizer 60% + jointing fertilizer 40%) was conducted at four sites (Chongqing, Renshou, Guanghan and Xichang) during two consecutive years, the SPAD value, canopy photosynthetic rate (CAP), photosynthetically active radia-tion (PAR) interception efficiency and grain yield were determined, and the nitrogen use efficiency and PAR use efficiency were calculated. The results showed that the SPAD of upper-most three leaves, CAP, PAR interception efficiency and grain yield were promoted with increasing nitrogen fertilizer, but nitrogen fertilizer use efficiency, productivity efficiency, uptake efficiency and use efficiency were decreased. The promoting effects of nitrogen fertilizer postponing were different among nitrogen levels, with the highest SPAD in N₁₈₀ treatment and the highest CAP in N₁₂₀ treatment. The light use efficiency of different nitrogen fertilization patterns differed among four sites. Furthermore, nitrogenous fertilizer postponing significantly increased nitrogen agricultural fertilizer use efficiency, productivity efficiency, uptake efficiency and apparent nitrogen recovery efficiency, but declined nitrogen use efficiency, and the performance of N_C was better than N_B. Among different sites, Guanghan had the highest SPAD, CAP, PAR interception efficiency and grain yield, Xichang had higher SPAD and nitrogen use efficiency, lower CAP and PAR use efficiency, Chongqing and Renshou had the lowest SPAD, light use efficiency, nitrogen use efficiency and grain yield. Biomass had significant positive relationships with grain yield, CPA, SPAD, and PAR interception efficiency. Therefore, the increase of nitrogen fertilizer could promote yield at all sites, and nitrogenous fertilizer postponing could further optimize grain yield component and improve nitrogen and light use effi-ciency. But the effects depended on the years and sites, thus a target nitrogen management mode should be site-specifically made.

Effects of controlled release blend bulk urea on soil nitrogen and soil enzyme activity in wheat and rice fields

ZHANG Jing-sheng, WANG Chang-quan, LI Bing, LIANG Jing-yue, HE Jie, XIANG Hao, YIN Bin, LUO Jing

2017, 28(6):  1899-1908.  doi:10.13287/j.1001-9332.201706.003

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A field experiment was conducted to investigate the effect of controlled-release fertilizer (CRF) combined with urea (UR) on the soil fertility and environment in wheat-rice rotation system. Changes in four forms of nitrogen (total nitrogen, ammonium nitrogen, nitrate nitrogen, and microbial biomass nitrogen) and in activities of three soil enzymes participating in nitrogen transformation (urease, protease, and nitrate reductase) were measured in seven fertilization treatments (no fertilization, routine fertilization, 10%CRF+90%UR, 20%CRF+80%UR, 40%CRF+60%UR, 80%CRF+20%UR, and 100%CRF). The results showed that soil total nitrogen was stable in the whole growth period of wheat and rice. There was no significant difference among the treatments of over 20% CRF in soil total nitrogen content of wheat and rice. The soil inorganic nitrogen content was increased dramatically in treatments of 40% or above CRF during the mid-late growing stages of wheat and rice. With the advance of the growth period, conventional fertilization significantly decreased soil microbial biomass nitrogen, but the treatments of 40% and above CRF increased the soil microbial biomass nitrogen significantly. The soil enzyme activities were increased with over 40% of CRF in the mid-late growing stage of wheat and rice. By increasing the CRF ratio, the soil protease activity and nitrate reductase activity were improved gradually, and peaked in 100% CRF. The treatments of above 20% CRF could decrease the urease activity in tillering stage of rice and delay the peak of ammonium nitrogen, which would benefit nitrogen loss reduction. The treatments of 40% and above CRF were beneficial to improving soil nitrogen supply and enhancing soil urease and protease activities, which could promote the effectiveness of nitrogen during the later growth stages of wheat and rice. The 100% CRF treatment improved the nitrate reductase activity significantly during the later stage of wheat and rice. Compared with the treatments of 40%-80% CRF, 100% CRF reduced the soil nitrate content of 20-40 cm soil layer in wheat significantly suggesting it could reduce the loss of nitrogen.

Effects of grafting and nitrogen fertilization on melon yield and nitrogen uptake and utilization

XUE Liang, MA Zhong-ming, DU Shao-ping

2017, 28(6):  1909-1916.  doi:10.13287/j.1001-9332.201706.004

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A split-field design experiment was carried out using two main methods of cultivation (grafting and self-rooted cultivation) and subplots with different nitrogen application levels (0, 120, 240, and 360 kg N·hm^-2) to investigate the effects of cultivation method and nitrogen application levels on the yield and quality of melons, nitrogen transfer, nitrogen distribution, and nitrogen utilization rate. The results showed that melons produced by grafting cultivation had a 7.3% increase in yield and a 0.16%-3.28% decrease in soluble solid content, compared to those produced by self-rooted cultivation. The amount of nitrogen accumulated in melons grafted in the early growth phase was lower than that in self-rooted melons, and higher after fruiting. During harvest, nitrogen accumulation amount in grafted melon plants was 5.2% higher than that in self-rooted plants and nitrogen accumulation amount in fruits was 10.3% higher. Grafting cultivation increased the amount of nitrogen transfer from plants to fruits by 20.9% compared to self-rooted cultivation. Nitrogen distribution in fruits was >80% in grafted melons, whereas that in self-rooted melons was <80%. Under the same level of nitrogen fertilization, melons cultivated by grafting showed 1.3%-4.2% increase in nitrogen absorption and utilization rate, 2.73-5.56 kg·kg^-1 increase in nitrogen agronomic efficiency, and 7.39-16.18 kg·kg^-1 increase in nitrogen physiological efficiency, compared to self-rooted cultivation. On the basis of the combined perspective of commercial melon yield, and nitrogen absorption and utilization rate, an applied nitrogen amount of 240 kg·hm^-2 is most suitable for graf-ting cultivation in this region.

Parameters modification and evaluation of two evapotranspiration models based on Penman-Monteith model for summer maize

WANG Juan, WANG Jian-lin, LIU Jia-bin, JIANG Wen, ZHAO Chang-xing

2017, 28(6):  1917-1924.  doi:10.13287/j.1001-9332.201706.016

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The dynamic variations of evapotranspiration (ET) and weather data during summer maize growing season in 2013-2015 were monitored with eddy covariance system, and the applicability of two operational models (FAO-PM model and KP-PM model) based on the Penman-Monteith model were analyzed. Firstly, the key parameters in the two models were calibrated with the measured data in 2013 and 2014; secondly, the daily ET in 2015 calculated by the FAO-PM model and KP-PM model was compared to the observed ET, respectively. Finally, the coefficients in the KP-PM model were further revised with the coefficients calculated according to the different growth stages, and the performance of the revised KP-PM model was also evaluated. These statistical parameters indicated that the calculated daily ET for 2015 by the FAO-PM model was closer to the observed ET than that by the KP-PM model. The daily ET calculated from the revised KP-PM model for daily ET was more accurate than that from the FAO-PM model. It was also found that the key parameters in the two models were correlated with weather conditions, so the calibration was necessary before using the models to predict the ET. The above results could provide some guidelines on predicting ET with the two models.

Alleviation effects of melatonin and Ca²⁺ on melon seedlings under salt stress

GAO Qing-hai, GUO Yuan-yuan, WU Yan, JIA Shuang-shuang

2017, 28(6):  1925-1931.  doi:10.13287/j.1001-9332.201706.005

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To assess the role of exogenous melatonin (MT) and Ca²⁺ in melon under salt stress, the content of mineral elements (Cl^-, Na⁺, K⁺, Mg²⁺, Ca²⁺), the values of Na⁺/K⁺, Na⁺/Ca²⁺, Na⁺/Mg²⁺, the activity of H⁺-ATP, the accumulation of osmotic substances and membrane lipid peroxidation in melon under salt stress were investigated in the environmental conditions (day/night 25/18 ℃) controlled by artificial climate chamber. The results showed that salt stress significantly inhibited growth of the melon seedlings with the increased contents of Cl^- and Na⁺ in roots and lea-ves, and the decreased contents of K⁺, Mg²⁺ and Ca²⁺, compared with the control. Under salt stress, exogenous application of MT or Ca²⁺ remarkably reduced the contents of Cl^- and Na⁺ in roots and leaves, increased the contents of K⁺, Mg²⁺ and Ca²⁺, and decreased values of Na⁺/K⁺, Na⁺/Ca²⁺ and Na⁺/Mg²⁺. Additionally, exogenous melatonin or Ca²⁺ increased H⁺-ATP activity and osmotic adjustments, and further alleviated cell membrane injuries imposed by salt stress, displaying lower MDA content and relative conductivity. Collectively, this work suggested that single or combined applications of exogenous MT and Ca²⁺ effectively reduced the content of Cl^- and Na⁺, improved ion balance by enhancing H⁺-ATP activity, and increased the content of osmotic adjustment substances for ameliorating membrane lipid peroxidation, thereby enhancing plant adaptation to salt stress, especially combined applications of exogenous MT and Ca²⁺. Our results further showed that the combined application of exogenous MT and Ca²⁺ resulted in a synergistic effect on increasing salt tolerance in melon seedlings.

Rapid screening and construction of high-efficient petroleum-degrading microflora through enzyme activity assay

WANG Sa, GUO Shu-hai, WANG Jia-ning, LI Feng-mei, WU Bo, ZHANG Qiang

2017, 28(6):  1932-1940.  doi:10.13287/j.1001-9332.201706.024

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It is of great practical significance to rapidly screen the mixed microbial flora for degradation of complex organic pollutants. It was the first time to rapidly calibrate the petroleum hydrocarbon degradation ability of highly efficient degrading microflora by measuring enzyme activity analyzed by the MicroResp^TM technology. The results were validated by the traditional shaking culture. According to the activity analysis of exoenzymes, endoenzymes and mixed enzymes, the degradation abilities of microflora and enzymes (including exoenzymes, endoenzymes and mixed enzymes) on petroleum hydrocarbon was investigated. The results showed that the enzyme activity assay had perfect sensitivity and high-throughput for rapidly detecting the degradation ability of the petroleum hydrocarbon. The test period was 12 h which was 10 times shorter than shaking culture for 120 microflora combinations. The maximum degradation extent of the petroleum hydrocarbon by microflora reached (56.1±1.6)%. It was concluded that the method of enzyme activity assay was high-efficient and high-throughput screening, which could be used in the construction of petroleum-degrading microflora.

Effects of CO₂ fertilization on photosynthesis and growth of cut Anthurium andraeanum in solar greenhouse in winter

YANG Ke-bin, MENG Fan-zhi, GUO Xian-feng

2017, 28(6):  1941-1947.  doi:10.13287/j.1001-9332.201706.021

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Aiming at the problem of the acute shortage of CO₂ in winter production of cut Anthurium andraeanum in solar greenhouse, the effect of CO₂ fertilization on photosynthetic characteristics and growth performance of A. andraeanum ‘Fire’ was investigated. Three treatments with different concentrations of CO₂ were designed, i.e., 700, 1000 and 1300 μmol·mol^-1, with receiving no extra CO₂ as the control. The results showed that for the CO₂-fertilized plants, the photosynthetic rate, intercellular CO₂ concentration and water use efficiency were significantly greater than those in the control plants after CO₂ fertilization for 60 days, and the largest increase range was observed in the 1000 μmol·mol^-1 CO₂ treatment, whereas the stomata conductance was significantly reduced compared with the control. Meanwhile, the contents of soluble sugar, starch and soluble protein in CO₂-fertilized plants were significantly higher than those in control plants. Moreover, the quality of cut flowers with CO₂ fertilization was remarkably superior to control flowers in term of the parameters including spathe size, spathe color, peduncle length, leaf growth performance and peduncle growth rate. The most superior improvement was observed in the 1000 μmol·mol^-1 CO₂ treatment. It was therefore concluded that CO₂ fertilization of 1000 μmol·mol^-1 could effectively improve the winter production of cut A. andraeanum in solar greenhouse.

Effects of elevated Cd, Zn and their combined effects on antioxidant system of tobacco

YANG Wei, WANG Hong-yan, YU Kai-yuan, LOU Hong, JI Guang-si, RUAN Ya-nan

2017, 28(6):  1948-1954.  doi:10.13287/j.1001-9332.201706.038

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A solution culture was conducted to study the effects of elevated Cd and/or Zn ions (0.1 mmol·L^-1 Cd²⁺, 0.15 mmol·L^-1 Zn²⁺, 0.1 mmol·L^-1 Cd²⁺+0.15 mmol·L^-1Zn²⁺) on seed germination rate and reactive oxygen species (ROS) level, antioxidants contents, antioxidant enzyme activities and product of membrane lipid peroxidation in tobacco seedling leaves. The results showed that compared to control, the seed germination rate decreased under elevated level of Cd²⁺or Zn²⁺, the superoxide radical (O₂^-· ) generation rate and hydrogen peroxide (H₂O₂) content in tobacco seedlings increased, the activities of catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR) increased, content of glutathione (GSH) and GSH/GSSG (oxidized glutathione) ratio decreased, and malondialdehyde (MDA) content increased. Compared to elevation of the level of only Cd²⁺ or Zn²⁺, the seed germination rate under elevation of both Cd²⁺ and Zn²⁺ levels was enhanced significantly; O₂^-· generation rate, contents of H₂O₂ and MDA decreased; CAT, APX and MDAR activities increased in the last stage of Cd²⁺ and Zn²⁺ exposure. Heavy metal Cd²⁺ or Zn²⁺ could induce the physiological injury to tobacco seedlings, and the toxic effects increased with prolonged stress time. The combined treatment of Cd and Zn could alleviate the toxicity of single stress on tobacco seedlings.

Responses of photosynthetic characteristics in leaves of Physocarpus amurensis and P opulifolius to drought stress

XU Nan, MENG Xiang-xin-yue, ZHAO Xi-ming, AI Chang, SUN Jia-qi, ZHANG Si-yu, ZHANG Cong-yang, ZHANG Hui-hui

2017, 28(6):  1955-1961.  doi:10.13287/j.1001-9332.201706.039

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This experiment was conducted to study the responses of photosynthetic gas exchange parameters and the chlorophyll fluorescence parameters in leaves to soil drought. Furthermore, the drought resistance abilities of the endangered native Physocarpus amurensis and the introduced P. opulifolius as well as their differences were studied. The results showed that the leaves of P. opulifolius wilted significantly, while the leaf water content and water use efficiency of the native P. amurensis were higher on the 7th day after soil drought. Soil drought reduced the net photosynthetic rate, stomatal conductance, and transpiration rate in the leaves of the two Physocarpus species, while the observed decrease of P. opulifolius was significantly higher than that of P. amurensis. On the 7th day after soil drought, the intercellular CO₂ concentration (C_i) of P. opulifolius was higher than that without drought treatment, while the C_i of P. amurensis was lower than that without drought treatment. The electron transfer rate (ETR) and photochemical quenching coefficient (q_P) in leaves of P. amurensis were clearly decreased, while differences of the light energy capture efficiency (F_v′/F_m′) in the PSⅡ reaction center were non-significant. However, F_v′/F_m′, ETR, and q_P in the lea-ves of P. opulifolius were all significantly decreased to greater extents compared to those in P. amurensis. On the 7th day after soil drought, a non-significant change was observed on the relative variable fluorescence (V_J) at site J of the OJIP curve of P. amurensis leaves, while V_J in leaves of P. opuli-folius was increased. The carbon assimilation ability of P. opulifolius leaves and the sensibility of PSⅡ function to soil drought were significantly higher than those of P. amurensis. The reduction in the photosynthetic capacity induced by soil drought was mainly due to the limitation of the stomatal factors for P. amurensis, but mainly due to the limitation of the non-stomatal factors for P. opulifolius.

Effect of salicylic acid on the growth and physiological performance of Ulva prolifera

YANG Liu, ZHUO Pin-li, ZHONG Jia-li, LI Ya-he, WANG Dong, GAO Xiu-xiu, XU Nian-jun

2017, 28(6):  1962-1968.  doi:10.13287/j.1001-9332.201706.013

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In order to study the effects of salicylic acid on the growth and physiological performance of Ulva prolifera with different proliferative styles, we took U. prolifera from vegetative (VU) and spore proliferative cells (SU) as materials, and cultured them under different salicylic acid concentrations to investigate their growth rate, chlorophyll fluorescence, SOD and soluble protein content. The results showed that the growth of both VU and SU was promoted by low concentration of salicy-lic acid, especially for VU. Under 0.2 μg·mL^-1 salicylic acid treatment, VU showed the highest relative growth rate of 21.0%, and the maximum photochemical efficiency (F_v/F_m) increased by 9.8% compared with SU. Additionally, salicylic acid affected the SOD activity significantly, and the enzyme activity of VU increased by 52.0% and 198.6% under 0.2 and 0.5 μg·mL^{- 1} salicylic acid treatment, and that of SU increased by 54.1% and 38.0%, respectively. Salicylic acid also promoted the relative electron transfer rate (rETR), photosynthesis and protein content of both VU and SU. In conclusion, salicylic acid benefited the growth of two kinds of U. prolifera, especially for VU.

Effects of elevated CO₂ concentration on growth and photosynthetic physiology of Hylotelephium erythrostictum

LIU Zi-juan, YANG Zong-peng, LI Ping, ZONG Yu-zheng, DONG Qi, HAO Xing-yu

2017, 28(6):  1969-1976.  doi:10.13287/j.1001-9332.201706.028

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We used an OTC (open top chamber) system to study the effects of elevated CO₂ concentration (atmospheric CO₂ concentration + 200 &#x03BC;mol·mol^-1) on the growth and photosynthetic physiology of Hylotelephium erythrostictum. Elevated CO₂ concentration decreased the leaf stomatal density of the upper and lower epidermis of H. erythrostictum by 16.1% and 16.7%, respectively. Elevated CO₂ concentration increased the vascular bundle in leaves and the cell volume near the upper epidermis. Elevated CO₂ concentration significantly increased the photosynthetic pigments content, net photosynthetic rate, stomatal conductance and transpiration rate of H. erythrostictum at night. In the evening of initial flowering stage, elevated CO₂ concentration significantly reduced the malic acid content by 64.0%, while increased cellulose content by 20.8%. In the morning of full flowering stage, elevated CO₂ concentration significantly increased the malic acid content by 27.0%, but had no effect on carbohydrate content. Elevated CO₂ concentration increased the number of branches per plant, stem mass and total biomass of H. erythrostictum. Elevated CO₂ concentration was beneficial to the growth of H. erythrostictum.

Effect of exogenous salicylic acid and ultraviolet radiation on Ulva prolifera under different light conditions

ZHUO Pin-li, ZHONG Jia-li, WANG Dong, XU Nian-jun, LI Ya-he

2017, 28(6):  1977-1983.  doi:10.13287/j.1001-9332.201706.032

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To study the combined effects of exogenous salicylic acid (SA) and ultraviolet radiation (UV) on marine green algae Ulva prolifera under high (160 μmol·m^-2·s^-1) and low (70 μmol·m^-2·s^-1) light intensities, the growth, chlorophyll fluorescence parameters, photosynthetic rate of oxygen, superoxide dismutase (SOD) activity, soluble polysaccharide and soluble protein contents were investigated after they grew with or without ultraviolet (UV, 3.2 W·m^-2) radiation in the presence or absence of SA (10 μg·mL^-1) for three days. The treatments included control group (CK), SA, UV and UV+SA treatments. Results showed that under the low light intensity without UV condition, the relative growth rate was enhanced, Chl a and soluble protein contents were decreased by SA. Under the high light intensity without UV condition, the relative growth rate was decreased, Chl a content, respiratory rate, photosynthetic rate of oxygen, soluble polysaccharide and soluble protein contents were enhanced by SA. Under the high light intensity with UV condition, the relative growth rate, Chl a and soluble polysaccharide contents were enhanced by UV+SA. Additionally, under the low light intensity with UV condition, compared to UV treatment, the maximum photochemical efficiency (F_v/F_m) and soluble protein contents were respectively increased by 139.8% and 32.2% under the UV+SA treatment. In conclusion, SA reduced the inhibitory effects of U. prolifera induced by UV, and the effects were more significant under the high light intensity.

Species composition and distribution patterns of ichthyoplankton within and outside artificial reefs in Qingshan Bay, Qingdao, China

GUO Shu-xin, GAO Dong-kui, ZHANG Xiu-mei, LI Wen-tao, ZHANG Pei-dong

2017, 28(6):  1984-1992.  doi:10.13287/j.1001-9332.201706.019

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To assess the fish attraction and shelter effects of the artificial reefs in Qingshan Bay of Qingdao, the species composition and distribution patterns of ichthyoplankton in artificial reefs were investigated using vertical and horizontal tows in 2014 and 2015. In total, 7306 fish eggs and 52 fish larvae, belonging to 4 orders, 9 families, 11 genera and 12 species, were collected during 7 cruises in spring, summer and autumn of 2014. In 2015, 10373 eggs and 159 fish larvae, belonging to 6 orders, 11 families, 14 genera and 15 species, were collected in the same period as in 2014. Perciformes were the majority for both fish eggs and larvae collected during the two surveys, followed by Pleuronectiformes. Among fish eggs, Sillago japonica and Cynoglossus joyneri were the most dominant species. Among fish larvae, S. japonica exhibited the highest dominance but was not the dominant species. The high dominant species in both fish eggs and larvae appeared alternately in diffe-rent seasons. The Margalef richness index (R), Shannon diversity index (H) and Pielou evenness index (J) of ichthyoplankton community were low during the spring, summer, and autumn, showing an instable community structure of ichthyoplankton. The average trophic level of adult fish corresponding to the ichthyoplankton collected in the two years were 3.71 and 3.78, respectively, and both belonged to low carnivorous fish of third trophic level. All the species were either warm-tempe-rate species or warm-water species, which was coincident with the warm-temperate zone characteristic. Comprehensive analysis showed that the biodiversity of the ichthyoplankton community within the artificial reef areas was higher than that outside the artificial reef areas, which might be linked to flow velocity, flow field characteristics, or spatial heterogeneity of artificial reef areas.

Predictive model based multimetric index of macroinvertebrates for river health assessment

CHEN Kai, YU Hai-yan, ZHANG Ji-wei, WANG Bei-xin, CHEN Qiu-wen

2017, 28(6):  1993-2002.  doi:10.13287/j.1001-9332.201706.015

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Improving the stability of integrity of biotic index (IBI; i.e., multi-metric indices, MMI) across temporal and spatial scales is one of the most important issues in water ecosystem integrity bioassessment and water environment management. Using datasets of field-based macroinvertebrate and physicochemical variables and GIS-based natural predictors (e.g., geomorphology and climate) and land use variables collected at 227 river sites from 2004 to 2011 across the Zhejiang Province, China, we used random forests (RF) to adjust the effects of natural variations at temporal and spatial scales on macroinvertebrate metrics. We then developed natural variations adjusted (predictive) and unadjusted (null) MMIs and compared performance between them. The core me-trics selected for predictive and null MMIs were different from each other, and natural variations within core metrics in predictive MMI explained by RF models ranged between 11.4% and 61.2%. The predictive MMI was more precise and accurate, but less responsive and sensitive than null MMI. The multivariate nearest-neighbor test determined that 9 test sites and 1 most degraded site were flagged outside of the environmental space of the reference site network. We found that combination of predictive MMI developed by using predictive model and the nearest-neighbor test performed best and decreased risks of inferring type I (designating a water body as being in poor biological condition, when it was actually in good condition) and type II (designating a water body as being in good biological condition, when it was actually in poor condition) errors. Our results provided an effective method to improve the stability and performance of integrity of biotic index.

Ecological risk assessment of typical karst basin based on land use change: A case study of Lijiang River basin, Southern China

HU Jin-long, ZHOU Zhi-xiang, TENG Ming-jun, LUO Nan

2017, 28(6):  2003-2012.  doi:10.13287/j.1001-9332.201706.001

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Taking Lijiang River basin as study area, and based on the remote sensing images of 1973, 1986, 2000 and 2013, the land-use data were extracted, the ecological risk index was constructed, and the characteristics of spatiotemporal variation of ecological risk were analyzed by “3S” technique. The results showed that land use structure of Lijiang River basin was under relatively reasonable state and it was constantly optimizing during 1973-2013. Overall, the ecological risk of Lijiang River basin was maintained at a low level. Lowest and lower ecological risk region was dominant in Lijiang River basin, but the area of highest ecological risk expanded quickly. The spatial distribution of ecological risk was basically stable and showed an obvious ring structure, which gra-dually decreased from the axis of Xingan County Town-Lingchuan County Town-Guilin City-Yangshuo County Town to other regions. Region with lowest ecological risk mainly distributed in natural mountain forest area of the north and mid-eastern parts of Lijiang River basin, and region with highe-st ecological risk concentrated in Guilin City. The ecological risk distribution of Lijiang River basin presented significant slope and altitude differences, and it decreased with increasing slope and altitude. During the study period, the area of low ecological risk converted to high ecological risk gra-dually decreased and vice versa. On the whole, the ecological risk tended to decline rapidly in the Lijiang River basin.

Seasonal changes of optical absorption properties of river and lake in East Liaohe River basin, Northeast China

SONG Yan-yan, SU Dong-hui, SHAO Tian-tian

2017, 28(6):  2013-2023.  doi:10.13287/j.1001-9332.201706.022

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The absorption characteristics of optically active constituents (OACs) in water column are important optical properties and basic parameters of establishing the inverse analysis model. Comparative analyses about seasonal variability of the optical absorption characteristics (phytoplankton, non-algal particles and chromophoric dissolved organic matter absorption characteristics) and water quality status of East Liaohe River basin were conducted based on the water samples in Erlong-hu Reservoir collected in June, September and October of 2011 and samples in East Liaohe River in October of 2012. The results demonstrated that the eutrophication status of Erlonghu Reservoir was lower in June, eutrophic in September and moderately eutrophic in October. Some of the sampling points of the East Liaohe River belonged to the middle trophic level and the other part belonged to the eutrophic level. The absorption coefficient of each component of water increased with increasing nutrient level. Besides, the absorption spectra of total suspended particulate of Erlonghu Reservoir in June and October were similar to that of non-algal particles, and chromophoric dissolved organic matter (CDOM) contributed most to the total absorption of water. The absorption spectra of total suspended particulate matter in September were similar to that of phytoplankton and phytoplankton was the dominant contributor to the total absorption. For samples of Erlonghu Reservoir in June and September, a_ph(440) and total phosphorus (TP) were correlated closely with each other. Significant correlation between a_ph(440) and dissolved organic carbon (DOC) of Erlonghu Reservoir in June was observed, while a_d(440) was only correlated with Chla. There were positive correlations between a_ph(675) and Chla, Carlson index (TLI) in Erlonghu Reservoir (September) and East Liaohe River. Obvious differences of water optical properties were found between river and lake located in the East Liaohe River basin as follows: There were two types of phytoplankton spectra curves of East Liaohe River and the contribution rates of different components varied greatly from sites to sites; Phytoplankton dominated spectral absorption in waters with high nutrition level (Erlonghu Reservoir in September and the East Liaohe River) while CDOM and the particles were both the main components for Erlonghu Reservoir in June and October; CDOM was composed of large-size molecules in waters of Erlonghu Reservoir in June and in the East Liaohe River in October and mainly of small-size molecules in Erlonghu Reservoir in September and October.

Relationship between the environmental factors and the CPUE (catch per unit effort) of Pseudocarcharias kamoharai in tropical Atlantic Ocean based on the GAM-Tweedie model

WANG Hao-zhan, DAI Xiao-jie, GUAN Wen-jiang, FAN Yong-chao

2017, 28(6):  2024-2032.  doi:10.13287/j.1001-9332.201706.010

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Crocodile shark (Pseudocarcharias kamoharai) is an important by-catch species of tropical Atlantic tuna longline fishery. The research on the relationship between the CPUE (catch per unit effort) and environmental factors can provide basic data for resource protection and management of this important species. Based on the Tweedie distribution theory, and the data of 1085 croco-dile sharks collected by the national observers of longline fishery from 2009 to 2015 in the tropical Atlantic Ocean (6.38° S-14.92° N, 42.03°-18.53° W), theGAM-Tweedie model was established, and the temporal and spatial effects of CPUE as well as the relationship with environmental factors were analyzed. The results showed the explained cumulative deviance of the crocodile shark’s CPUE to be 40.2%. The spatio-temporal factors (year, month, longitude, latitude) all hadsignificant effects (P<0.05) on the crocodile shark CPUE. The environmental factors such as sea surface height, chlorophyll a concentration, weather code, sea surface salinity and sea level pressure all had significant effects on CPUE (P<0.05). However, the Beaufort wind force and lunar calendar did not have significant effects on theCPUE (P>0.05). Significant correlation (P<0.05) was observed at different latitudes and in months between the sea surface temperature and CPUE. The standardized CPUE of the crocodile shark in 2009-2015 showed a fluctuating increase trend.

Damage of deltamethrin on tissue and cell DNA in hepatopancreas of Pagrosomus major

ZHENG Hui-dong

2017, 28(6):  2033-2039.  doi:10.13287/j.1001-9332.201706.014

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In order to study the toxic effect of deltamethrin on the hepatopancreas of Pagrosomus major with sub-acute exposure, Pagrosomus major were divided into 5 groups with different doses of semi-static exposure. The damage of the hepatopancreas tissue of Pagrosomus major was analyzed by microscopy observation and the DNA damage of the cells was analyzed by comet assay technique after 25 days exposure. The results showed that different degrees of congestion, nuclear enrichment and cell necrosis appeared in hepatopancreas of 0.025, 0.125, 0.250, 0.375 μg·L^-1 exposure concentrations. The higher the exposure concentration, the variations of tissue and cell were more significant. DNA damages in the hepatopancreas cells of all exposed group were observed. The co-met rate, percentage of tail DNA and the olive moment were significantly different from the control group (P<0.05). Linear regression analysis showed that the exposure concentration was significantly positively correlated with the tailing rate and the tail length (P<0.01). The indexes were significantly related to the concentration of deltamethrin exposure with the coefficient of determination between 0.909-0.996. It was suggested that deltamethrin could cause various degree of damage to the tissue and cellular DNAs in the hepatopancreas of Pagrosomus major in a linear responsive manner.

Carbon footprint of buildings in the urban agglomeration of central Liaoning, China

SHI Yu, YUN Ying-xia, LIU Chong, CHU Ya-qi

2017, 28(6):  2040-2046.  doi:10.13287/j.1001-9332.201706.007

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With the development of urbanization in China, buildings consumed lots of material and energy. How to estimate carbon emission of buildings is an important scientific problem. Carbon footprint of the central Liaoning agglomeration was studied with carbon footprint approach, geographic information system (GIS) and high-resolution remote sensing (HRRS) technology. The results showed that the construction carbon footprint coefficient of central Liaoning urban agglomeration was 269.16 kg·m^-2. The approach of interpreting total building area and spatial distribution with HRRS was effective, and the accuracy was 89%. The extraction approach was critical for total carbon footprint and spatial distribution estimation. The building area and total carbon footprint of central Liaoning urban agglomeration in descending order was Shenyang, Anshan, Fushun, Liao-yang, Yingkou, Tieling and Benxi. The annual average increment of footprint from 2011 to 2013 in descending order was Shenyang, Benxi, Fushun, Anshan, Tieling, Yingkou and Liaoyang. The accurate estimation of construction carbon footprint spatial and its distribution was of significance for the planning and optimization of carbon emission reduction.

Reviews

Mechanism of hypoxia-tolerance and community structure of aerobic methanotrophs in O₂-limited environments: A review

MA Ruo-chan, WEI Xiao-meng, HE Ruo

2017, 28(6):  2047-2054.  doi:10.13287/j.1001-9332.201706.023

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Methane bio-oxidation plays an important role in the global methane balance and greenhouse gases mitigation. Oxygen (O₂) is one of the significant factors in methane bio-oxidation. The O₂ concentration in the environments not only can affect community structure and activity of aerobic methanotrophs and the distribution of methane-derived carbon, but also aerobic methanotrophs have various ways of metabolism at different O₂ concentrations. It is meaningful for carbon cycle and biodiversity of methane-driven ecosystem to understand the hypoxia-tolerance mechanisms of aerobic methanotrophs and methane bio-oxidation in O₂-limited environments. In this paper, the activity and community structure of aerobic methanotrophs in O₂-limited environments were summarized. The hypoxia-tolerance mechanism of aerobic methanotrophs and the relationship between methanotrophs and non-methanotrophs in O₂-limited environments were reviewed. Future studies about aerobic methanotrophs were also discussed.

Research progress of the interaction between Apis mellifera and Varroa destructor mediated by pheromones

ZHANG Hao-hao, LIU Zhen-guo, GONG You-hui, DIAO Qing-yun

2017, 28(6):  2055-2062.  doi:10.13287/j.1001-9332.201706.012

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Varroa destructor is a virulent ectoparasitic mite of western honeybee (Apis mellifera), and considered the greatest threat to apiculture around the world. Chemical method is widely used for the management of this mite. However, this method can easily induce the resistance of V. destructor to acaricides, toxicity of acaricides to honeybee and the residues in bee products. Therefore, many safe preventions and control techniques were developed to treat mite in recent years. Using pheromones of honeybee to control V. destructor would be a main tendency. A lot of studies indicated that Varroa mites are able to use honeybee pheromones to distinguish the development stages of the hosts, and show high selectivity for appropriate hosts at a special stage. In recent years, a lot of honey bee pheromones were reported to have effect on V. destructor, including pheromones from adult honeybee, pupa and brood. Some of them have repellent effect on V. destructor, while others have attractant effect on V. destructor. This article reviewed the progresses in pheromones categories, major chemical compositions, and their effects to V. destructor, which would suggest important avenues for further researches and applications in mite control.

Application of species distribution models in the prediction of marine potential habitat: A review

YANG Xiao-long, YANG Chao-jie, HU Cheng-ye, ZHANG Xiu-mei

2017, 28(6):  2063-2072.  doi:10.13287/j.1001-9332.201706.006

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The relationship between the distribution of halobios and environmental variables has been a focus of present research in marine ecology. Species distribution models (SDMs) have been widely employed to predict the distribution patterns and potential habitat suitability assessments of marine species and provide an efficient approach for marine biodiversity conservation, invasive species prevention, and fishery management. SDMs mainly include habitat suitability index models, mechanism models, and statistical models. In this paper, the theoretical basis of SDMs was firstly concluded and summarized. Next, the exploitation and case-studies of SDMs, especially the statistical models, for predicting potential distribution of marine species were reviewed. Then, comparisons of various methods for variable selection and model validation were made. Conclusions could be drawn that Akaike information criterion showed excellent performance when it came to variable selection, while Kappa coefficient and Area Under receiver operating character Curve (AUC) were widely used in relation to model validation. Finally, problems and prospects of SDMs were discussed. With the development of research on physiological characteristics, using mechanism models to predict potential habitats of halobios would become a trend.

Silver nanoparticles in natural water environment: Source, analysis and transformation

YANG Yue-suo, WANG Chen,YUAN Xue-mei, AN Chang-wei, YANG Xin-yao

2017, 28(6):  2073-2082.  doi:10.13287/j.1001-9332.201706.011

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Silver nanoparticles (AgNPs) as one of the most widely used metal nanomaterials can enter soil and water environment via various pathways, exert toxicity on water-borne organisms and deteriorate the aquatic eco-environment. With complex composition of natural water, the physicochemical property of AgNPs as nano materials makes their transformation process more complicated in water system. Therefore, understanding of the fate and transport of AgNPs in aqueous environment is extremely important for water quality management and protection of the eco-environment. Deve-lopment of modern science and technology has made it possible to study the process of the dissolution of AgNPs in environment. This paper summarized the source and risk of AgNPs in environment, analyzed impacts of environmental factors such as pH, dissolved oxygen, ionic strength and intrinsic factors of AgNPs such as particle size and coating on the AgNPs transformation in water environment, and summarized the main analytical techniques for the AgNPs size, potential and morphology. Finally, this paper pointed out the major research gaps in the current research and provided prospective for the future research.