Table of Content

20 October 2018, Volume 29 Issue 10

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Research paper

Long-term monitoring of tree population dynamics of broad-leaved Korean pine forest in Changbai Mountains, China

XU Wei-ze, LIU Qi-jing, MENG Sheng-wang, ZHOU Guang

2018, 29(10):  3159-3166.  doi:10.13287/j.1001-9332.201810.004

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Based on four investigations of a one-hectare permanent plot in Changbai Mountains from 1981 to 2016, the changes of tree species composition and structure of broad-leaved Korean pine forest were examined, and diameter distribution, spatial pattern distribution, and quantitative changes of each tree species were analyzed. The results showed that there were little changes in tree species composition and an overall decreasing trend in total density in 35 years. Both basal area and stand volume were 43-45 m²·hm^-2 and 474-496 m³·hm^-2, respectively. Pinus koraiensis was the most dominant species, whose basal area and volume accounted for 57.8%-59.7% and 62.5%-65.4% of the total in the community, respectively. All dominant species showed random distribution and changed little in 35 years. The DBH distribution of P. koraiensis was in a near-to-normal form. Total species showed a reversed “J” shape. The number of dead trees was the largest in small DBH class (10-26 cm) with the percentage of 30%. The percentage of dead trees was the largest in intermediate class (30-50 cm) with 30%-50%. Except Acer mono, all species in the tree layer showed little recruitment, with mortality rate being higher than recruiting rate. Specially, P. koraiensis had no saplings or recruitment, and the population was in decline. The regeneration of dominant species such as P. koraiensis and Tilia amurensis was hindered in the original broad-leaved Korean pine forest, the population maintenance of which might need natural disturbance.

Effects of exogenous nitrogen input and water change on litter decomposition in a desert grassland

GAO Hai-yan, HONG Mei, HUO Li-xia, YE He, ZHAO Ba-yingnamula, DE Hai-shan

2018, 29(10):  3167-3174.  doi:10.13287/j.1001-9332.201810.005

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Under the background of global climate change, atmospheric nitrogen deposition and precipitation are undergoing substantial changes, which leads to an uncertainty on litter decomposition in desert grassland. The experiment was set up with a split-plot design. There were three precipi-tation treatments, including natural precipitation, an increase of 30% and a decrease of 30%, and four levels of nitrogen application, including 0 (N₀), 30 (N₃₀), 50 (N₅₀) and 100 kg·hm^-2·a^-1 (N₁₀₀). A two-year decomposition experiment aimed to examine how water and nitrogen manipulations interactively influence litter decomposition of three dominant species in the desert grassland, i.e., Salsola collina, Stipa breviflora and Kochia prostrata. The results showed that litter mass remaining rate decreased with time, which was consistent with Olson negative exponential decay model. Litter decomposition coefficient (k) was highest for S. collina, followed by S. breviflora and K. prostrata. The decomposition coefficient (k=0.028) was the highest under the treatment of increased precipitation 30% and N application level of 100 kg·hm^-2·a^-1. Under single factor treatment, litter decomposition was the fastest under increased precipitation 30% and N application level of 50 kg·hm^-2·a^-1. Under the combined water and nitrogen treatments, litter decomposition under increased precipitation 30% and N application level of 100 kg·hm^-2·a^-1 was the fastest. The initial nitrogen content was the greatest for S. collina, followed by S. breviflora and K. prostrata. The decomposition coefficients were positively correlated with initial nitrogen contents for S. collina and S. breviflora. The total carbon content, cellulose content, lignin content, C/N, lignin/N and cellulose/N were higher in K. prostrata than in S. breviflora and S. collina. The litter characteristics were negatively correlated with decomposition coefficient for S. collina. For S. breviflora and K. prostrata, the decomposition coefficients decreased with increasing C/N, lignin/N and cellulose/N. The results indicated that the decomposition rate was the highest in S. collina, and the lowest in K. prostrata. The findings suggest that appropriate amounts of added water and nitrogen will contribute to accelerating litter decomposition, promoting nutrient cycling, and will play an important role in the sustainability and ecological balance of the desert grassland .

Comprehensive evaluation and construction of drought resistance index system in Hydrangea macrophylla

CAI Jian-guo, ZHANG Yi, SUN Ou-wen, YANG Qian-qian

2018, 29(10):  3175-3182.  doi:10.13287/j.1001-9332.201810.002

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With the continuous drought stress treatment to five Hydrangea macrophylla varieties of different abilities of drought resistance, twenty-five physiological-biochemical indices were mea-sured. We evaluated the drought resistance of different varieties and established the mathematic model. The results showed that leaf mass per area, cell membrane permeability (CMP), the content of malonaldehyde (MDA), the activity of superoxide dismutase (SOD), soluble sugar content, proline content, intercellular carbon dioxide and non-photochemical quenching coefficient were significantly increased under drought stress for twenty days. In contrast, relative water content, net photosynthetic rate, stomatal conductance, transpiration rate, actual photochemical efficiency of PSⅡ and electron transport rate (ETR) were significantly decreased. The principal component analysis classified those indices into three independent comprehensive indices (accumulative contribution of 87.1%). The principal component 1 mainly reflected the information of photosynthetic and fluorescence. The principal component 2 mainly reflected the information of plant vigor. The principal component 3 mainly reflected the information of membrane system and osmotic adjust system. Five H. macrophylla varieties were divided into three categories by clustering analysis: drought-tolerant type (including H. macrophylla ‘Lavblaa’) and H. macrophylla ‘Taube’), intermediate type (H. macrophylla ‘You and me romance’), and drought-intolerant type (including H. macrophylla cv. Endless summer bride and H. macrophylla ‘Tricolor’). Comprehensive evaluation of drought resis-tance (D value) showed that the ability of drought resistance decreased in order of H. macrophylla ‘Lavblaa’ > H. macrophylla ‘Taube’> H. macrophylla ‘You and me romance’> H. macrophylla cv. Endless summer bride > H. macrophylla ‘Tricolor’. Four influential indices for drought resis-tance including CMP, the activity of peroxidase (POD), soluble protein contents (SP) and ETR was screened by stepwise regression analysis, which could be used for the rapid identification of drought resistance of H. macrophylla.

Measuring the dynamics of leaf area index of vegetation using fisheye camera

NIU Xiao-tao, FAN Jun, WANG Sheng, WANG Qiu-ming

2018, 29(10):  3183-3190.  doi:10.13287/j.1001-9332.201810.012

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The rapid and accurate measurement of LAI is of great importance for the research of ecological processes. Photos from typical land use types in the northern Loess Plateau, including Caragana, Salix, alfalfa, wild grass, soybean and maize, were measured by digital hemispherical photography (DHP). Meanwhile, photos were daily taken by video camera with fisheye lens and the pictures were analyzed by image processing software to obtain the dynamics of LAI in soybean, maize and Caragana fields. The results showed that a linear correlation existed between the LAI measured by DHP and LAI-2200. The coefficient of determination (R²) was 0.85 (P<0.05) and root mean square error (RMSE) was 0.256. The key parameters of professional software were affected by the local solar radiation. When the downward lens was used, the green index was the key parameter which increased with the increase of solar radiation. However, the brightness index decreased with the increase of solar radiation when the lens was upward. Through the adjustment of the key parameters, the results of LAI of maize, soybean, and Caragana were consistent with the LAI-2200 results, well reflecting LAI dynamics during the plant growth. The downward lens in Caragana field was better. The fisheye camera could be used for monitoring the dynamic LAI of different vegetations.

Responses of greenhouse gas emission to simulated nitrogen deposition in Calamagrostis angustifolia wetlands of Sanjiang Plain, China

ZHANG Rong-tao, SUI Xin, XU Nan, ZHONG Hai-xiu, FU Xiao-yu, NI Hong-wei

2018, 29(10):  3191-3198.  doi:10.13287/j.1001-9332.201810.001

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A long-term simulated nitrogen deposition experiment was carried out in Ecological Locating Research Station of the Institute of Nature and Ecology of Heilongjiang Academy of Sciences, with three different treatments including low nitrogen treatment (40 kg N·hm^-2·a^-1), high nitrogen treatment (80 kg N·hm^-2·a^-1) and the control (0 kg N·hm^-2·a^-1). The greenhouse gas emission fluxes were measured using a static box-gas chromatography method, with environmental factors being simultaneously investigated to understand the responses of greenhouse gas emission to the nitrogen deposition in the Calamagrostis angustifolia wetland. The results showed that low and high nitrogen treatments significantly increased the greenhouse gas emission fluxes. The CO₂ emission flux increased by 47.5% and 47.9%, the CH₄ emission fluxes increased by 76.8% and 110.1%, and the N₂O emission fluxes increased by 42.4% and 10.6% in low nitrogen treatment and high nitrogen treatment, respectively. Low nitrogen input changed the seasonal dynamics of N₂O emission fluxes but had no significant effect on that of CO₂ and CH₄ emissions. High nitrogen treatment did not affect the seasonal dynamics of greenhouse gas emissions. Soil temperature significantly positively correlated with CO₂ and CH₄ emission fluxes. There was no correlation between soil temperature and N₂O emission flux because the factors affecting N₂O emission were complex.

Effects of soil in larch plantations on the growth of Picea koraiensis and P. crassifolia seedlings

DONG Hui, YANG Li-xue

2018, 29(10):  3199-3205.  doi:10.13287/j.1001-9332.201810.003

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In addition to soil fertility decline, larch plantation had difficulty in natural regeneration, which challenges the healthy development and sustainable management. A greenhouse experiment was conducted with two kinds of shade-tolerant conifer species (Picea koraiensis and P. crassifolia) to examine the responses of seedling growth of two spruce species on sterilization treatment of larch plantation soils (except spruce biological characteristics), which would provide scientific basis for the transformation, regeneration and multi-storied forest cultivation of larch. The results showed that soil sterilization did not significantly affect the biomass of P. koraiensis and P. crassifolia seedlings. The biomass of P. koraiensis (75.6 and 72.2 mg, respectively) was significantly higher than that of P. crassifolia (55.6 and 60.0 mg, respectively) in both unsterilized and sterilized soils. The root diameter, cortical thickness, stele diameter and stele to root diameter ratio of the first-order roots of P. koraiensis were not affected by soil sterilization. In contrast, the root diameter, stele diameter and stele to root diameter ratio of the first-order roots except cortical thickness of P. crassifolia in sterilized soil (331.30 μm, 143.23 μm and 43.3%, respectively) were significantly higher than those in unsterilized soil (276.50 μm, 99.35 μm and 36.0%), showing a more positive response to sterilized soil. It indicated that P. koraiensis had better adaptability in larch plantation. Because the microbial community function was dominated by ectomycorrhiza which displayed some antagonisms for soil pathogen, seedlings of two spruce species could escape from soil pathogens accumulated in larch plantation and grow normally, with P. koraiensis having more advantages than the P. crassifolia.

Effects of different nitrogen supply levels on the yield of Orychophragmus violaceus, soil residual inorganic nitrogen, and nitrogen balance

BAI Jin-shun, CAO Wei-dong, ZENG Nao-hua, GAO Song-juan, YANG Lu, ZHOU Guo-peng

2018, 29(10):  3206-3212.  doi:10.13287/j.1001-9332.201810.030

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Understanding the responses of winter green manure February orchid (Orychophragmus violaceus) to different levels of nitrogen (N) supply in Northern China and determining the optimal soil N supply level to meet N demands of green manure production with high yield and efficiency, could provide a theoretical foundation and practice reference for maximizing ecological effects of green manure and optimizing N management for spring maize-green manure rotation system in intensive farmland in Northern China. We carried out a field experiment in a site which had received no fertilizer for many years. The aboveground biomass accumulation, N uptake of February orchid and soil residual inorganic N before green manure incorporation, as well as the N balance during the green manure growing season were determined under different levels of N supply. The results showed that N fertilizer application significantly increased the biomass and N uptake of February orchid under low soil inorganic N content (15 kg·hm^-2 in 0-90 cm soil layer). At the application rate of 90 kg·hm^-2, the biomass (dry mass) and N uptake reached the maximum, being 2031 and 42 kg·hm^-2, respectively. The soil residual inorganic N amount rose with the increases of N fertilizer application before sowing, growing very rapidly once the application rate was over 60 kg·hm^-2. With the increases of N application rate, the calculated apparent N balance changed from deficit to surplus in the growing season of February orchid. The inputs and outputs of N reached a balance at the application rates of 60 to 90 kg·hm^-2. The relationships between February orchid biomass, N uptake, soil inorganic N before green manure incorporation, and soil N supply amount (0-90 cm preplant soil inorganic N content plus N application rate) could be fitted by the quadratic, linear plus plateau and exponential models respectively. Based on the simulation, we calculated the preplant soil N supply and soil residual inorganic N content before green manure incorporation would be 136 and 78 kg·hm^-2 individually, as the biomass of February orchid reached the maximum (2010 kg·hm^-2). While N uptake was at the highest level of 40 kg·hm^-2, the biomass of February orchid was 95% of the maximum biomass mentioned above (1919 kg·hm^-2) and the soil residual inorganic N before green manure incorporation decreased to 57 kg·hm^-2 whose corresponding minimum soil N supply amount was 105 kg·hm^-2. This value was quite near to the recommended soil residual inorganic N (100 kg·hm^-2) after maize harvest under optimized N management in Nor-thern China. Taken together, our results showed that the level of soil N supply should be at approximately 100 to 105 kg·hm^-2 in spring maize-winter green manure system for improving tradeoffs between agronomic and environmental impacts.

Predicting the influence of future climate change on the suitable distribution areas of Elaeagnus angustifolia

ZHANG Xiao-qin, LI Guo-qing, DU Sheng

2018, 29(10):  3213-3220.  doi:10.13287/j.1001-9332.201810.018

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Climate change significantly affects geographic distribution of plants worldwide. Understanding the influence of climate change on the suitable areas of afforestation tree species in China and taking timely countermeasures are crucial for improving the effectiveness of afforestation. Elaeagnus angustifolia is a good species for ecological restoration of degraded lands and control of desertification. Using MaxEnt and GIS, we predicted the changes of climatically suitable areas of this species under future climate scenarios, based on 182 records from herbaria and published literatures, and 13 climatic factors from BIOCLIM, Holdridge life zone and Kira index. The results showed that the four climate scenarios in 2070s had different effects on the climatically suitable areas of this species. The suitable areas would shrink in the lowest greenhouse gas emission (RCP 2.6) scenario. The shrinking areas were mainly located in the edge of the currently suitable areas in the northwest. The suitable areas would expand in the lower (RCP 4.5), the higher (RCP 6.0) and the highest (RCP 8.5) greenhouse gas emission scenarios. The expanding areas were mainly located in the northwestern arid regions of warm temperate zone, and northeastern sub-humid regions of middle temperate zone. There were obvious expansions in the northern arid and semi-arid regions of middle temperate zone, and southern humid regions of north-subtropical zone under RCP 8.5 scenario. The geographical centroids of future suitable ranges would move with a speed of 6-19 km·(10 a)^-1. The altitudinal centroids were predicted to move to lower regions with a speed of 3-20 m·(10 a)^-1. The stably suitable areas accounted for 83%-98% of the current distribution ranges of this species, which were generally stable under future climate change scenarios.

Responses of soil nutrients and biological characteristics to nitrogen deposition in Hulun Buir Grassland, China

ZHU Ying, LI Huan-ru, YU Qiang, CHEN Xiao-dong, WEI Kai, LUO Wen-tao, CHEN Zhen-hua, CHEN Li-jun

2018, 29(10):  3221-3228.  doi:10.13287/j.1001-9332.201810.040

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Studies on effects of nitrogen deposition were mainly focused on temperate grasslands in Inner Mongolia of China. In addition, there are substantial differences between the present simulation methods and the natural nitrogen deposition. A three-year experiment was carried out to compare the effects of simulation methods (common urea and slow-released urea) and nitrogen deposition rates (0, 25, 50, 75, 100, 150, 200 and 300 kg N·hm^-2·a^-1) on soil nutrients and biological characteristics in Hulun Buir Grassland. We found that simulated nitrogen deposition had significant influences on soil chemical properties, biological properties and enzyme activities. With the increases of nitrogen deposition, soil pH declined with the greatest extent of 0.2 units, while the highest concentrations of total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) increased by 5-7 times and 12%-36%, respectively. There was a decline trend for soil total phosphorus (TP) and organic phosphorus (TOP). Microbial biomass and metabolic activity increased firstly and then decreased. Moderate simulated nitrogen deposition rates significantly increased soil carbon, nitrogen and phosphorus related enzyme activities. Compared to common urea, using slow-released urea to simulate nitrogen deposition decelerate the decline of soil pH and the increase of dissolved nutrients, and smoothed the change of microbial biomass, metabolic activity, and nitrogen hydrolyzed enzyme activities. Overall, the results confirmed that continuous nitrogen input caused the decline of soil pH and the increase of bioavailable carbon and nitrogen, and then changed microbial biomass and activity.

Effects of different densities of mixed-cropping on ¹³C-photosynthate distribution and grain yield of maize

HU Dan-dan, ZHANG Ji-wang, LIU Peng, ZHAO Bin, DONG Shu-ting

2018, 29(10):  3229-3236.  doi:10.13287/j.1001-9332.201810.021

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To explore the effects of different densities of mixed-cropping on ¹³C-photosynthate distribution and grain yield of maize, we measured photosynthetic characteristics, ¹³C-photosynthate distribution, dry matter accumulation, and grain yield under different planting densities (LD, 67500 plants·hm^-2 and HD, 97500 plants·hm^-2) under mixed-cropping (M, 1:1, 2:2) and monoculture of Zhengdan958 (ZD) and Denghai605 (DH). The results showed that with the increases of planting density, grain yield, ¹³C-photosynthate allocation to grain, dry matter accumulation, and leaf area index (LAI) increased, but the chlorophyll content and net photosynthetic rate decreased. No significant difference was observed between the monoculture and mixed-cropping at the density of 67500 plants·hm^-2. However, at 97500 plants·hm^-2, LAI, chlorophyll content, net photosynthetic rate and dry matter accumulation in mixed-cropping were higher than that in monoculture. Mixed-cropping promoted the transport of dry matter from the vegetative organs such as stem to the grain and the distribution of ¹³C-photosynthates to grain. Grain yield of summer maize significantly increased in mixed-cropping due to the increase of 1000-grain mass. Under high plant density, the mixed-cropping could enlarge photosynthetic area, maintain higher net photosynthetic rate, increase dry matter accumulation, improve the distribution of dry matter, promote the distribution of ¹³C-photosynthates to grains and thus increase the grain yield. Our results indicated that mixed-cropping could significantly increase the yield of close planting summer maize in Huang-Huai-Hai Plain.

Effect of long-term fertilization on wheat yield under different precipitation patterns

LI Xiao-zhou, HAO Ming-de, ZHAO Jing, WANG Zhe, FU Wei, LIU Zeng-zhao

2018, 29(10):  3237-3244.  doi:10.13287/j.1001-9332.201810.025

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Rational application of nitrogen and phosphorus is one of the main pathways to enhance wheat yield. The optimum dosage of nitrogen and phosphorus used in different precipitation patterns was studied using the binary quadratic regression equation, which could provide a basis for fertilization of wheat in Loess Plateau. The results showed that the amount of nitrogen and phosphorus ferti-lizer required for the maximum yield was dependent on precipitation patterns. The maximum wheat yield in normal years was 4229 kg·hm^-2, with the dosage of nitrogen and phosphorus applied being 172 and 164 kg·hm^-2, respectively. The maximum wheat yield in wet years was 4896 kg·hm^-2, with the dosage of nitrogen fertilizer being 2% more than that in normal years, 175 kg·hm^-2, and the dosage of phosphorus was about 1% less than that in normal years, 162 kg·hm^-2. The application of nitrogen and phosphorus in dry years was about 16% and 5% less than that in normal years. When the dosage was more than that, wheat yield began to decline. The economic optimum fertilization differed in different precipitation patterns. The economic optimum nitrogen and phosphorus fertilization in normal years was 161 and 151 kg·hm^-2, while in dry years it was 135, 143 kg·hm^-2, respectively. The economic optimum fertilization in wet years was about 3% and 1% more than that in normal years, 167 and 153 kg·hm^-2. The economic optimum fertilization was 6%-8% lower than optimum amount of fertilization. In actual production, it was recommended to reduce the amount of nitrogen and phosphorus by 10% in order to improve the utilization rate of fertilizer and get the maximum benefit.

Regulatory effects of bundled straw covering on winter wheat yield and soil thermal-moisture utilization in dryland

YANG Chang-gang, CHAI Shou-xi

2018, 29(10):  3245-3255.  doi:10.13287/j.1001-9332.201810.027

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Bundled straw covering (BSC), using corn whole straw for partial coverage planting, is a novel dryland cultivation technique. To examine the effects of BSC on the thermal-moisture status and winter wheat yield under typical arid and semiarid conditions in the Loess Plateau of Northwest China, soil temperature, soil water content and consumption, grain yield and water-use efficiency were compared for four treatments, including no-tillage with straw mulch (NTS), whole field plastic mulching with soil covering on the top of the plastic mulch and bunch-seeding (PFM), open field cultivation (CK) and BSC during three growing seasons from 2013 to 2016. The results showed that PFM significantly increased soil temperature of 5-20 cm depth before jointing stage, while the warming effect of BSC and NTS was mainly in the wintering period. The three kinds of coverage methods after jointing stage had significant cooling effects. Both BSC and PFM significantly improved soil water storage effect during the fallow period. BSC significantly elevated soil moisture in the depth of 0 to 200 cm in the whole growing season. The improvement of soil moisture by PFM and NTS mainly occurred before the heading stage, and soil moisture in PFM treatment gradually decreased after heading stage. BSC and PFM significantly increased water consumption in the whole growth period and increased that during the jointing stage to the flowering stage, and promoted the utilization of soil moisture below 120 cm. Compared with CK, BSC, NTS and PFM significantly increased the number of panicles per unit area and biomass at maturity. In those three treatments, grain yield was increased by 19%-52%, 14%-30% and 15%-60%, respectively, and the annual water use efficiency was increased by 19%-61%, 14%-31% and 15%-58%, respectively. BSC had the same potential for increasing yield and water use efficiency as PFM. Based on factors such as winter wheat yield, soil thermal-moisture utilization and annual water consumption, BSC is a high-yield and efficient cultivation method that is conducive to the sustainable development of dryland agriculture in Northwest China.

Field microclimate and yield for proso millet intercropping with mung bean in the dryland of Loess Plateau, Northwest China

GONG Xiang-wei, LI Jing, MA Hong-chi, CHEN Guang-hua, WANG Meng, YANG Pu, GAO Jin-feng, FENG Bai-li

2018, 29(10):  3256-3266.  doi:10.13287/j.1001-9332.201810.028

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Based on the ecological environment features of Loess Plateau, we examined field microclimate characteristics and yield of four different intercropping patterns for proso millet (P) and mung bean (M) including 2:2, 4:2, 4:4, 2:4. The results showed that, compared with monoculture, intercropping increased plant height, leaf area index (LAI) and chlorophyll content (SPAD) of proso millet in its late growth stage, while LAI and SPAD of mung bean decreased due to the shade of the high proso millet. Mung bean appeared spindly growth for a while by increasing the plant height. Moreover, upper canopy illumination and air temperature during grain filling stage of proso millet decreased under intercropping conditions, but relative humidity substantially increased. These changes regulated soil temperature and light leakage, which decreased under intercropping systems, and thereby led to a cold and wet ecological environment. Poor atmospheric and light conditions formed a relative closure growth environment for mung bean, which suppressed its growth. The panicles, spike length, grain mass per plant and 1000-grain mass of proso millet under 2P2M, 4P2M, 4P4M and 2P4M treatments was significantly increased by 7.5%-45.0%, 2.2%-12.2%, 35.4%-94.0% and 2.3%-4.7%, respectively. This caused a 5.6%-20.7% increase of yield than the mono-culture. The branch number, pods per plant, grain mass per plant and 100-grain mass in mung bean were decreased under different intercropping treatments, and the yield was significantly reduced by 34.8%. Land equivalent ratios (LER) of each intercropping pattern were all greater than 1. Among them, LER of 2P4M was the maximum (1.86), and 2P4M treatment held relatively reasonable composite configuration. Our results suggested that 2:4 ratio of proso millet/mung bean intercropping patterns performed better than other ratios on the Loess Plateau.

Effects of the reduction of controlled-release urea application on nitrogen leaching in double cropping paddy field

TIAN Chang, ZHOU Xuan, LIU Qiang, XIE Gui-xian, RONG Xiang-min, ZHANG Yu-ping, HUANG Si-yi, PENG Jian-wei

2018, 29(10):  3267-3274.  doi:10.13287/j.1001-9332.201810.029

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Nitrogen (N) leaching is a major pathway of N losses in paddy fields. Here, an experiment was conducted to assess the effects of the reduction of controlled-release urea application on grain yield and N leaching in a double-cropping paddy field. Fertilization treatments included zero-N (CK, control, 0 kg N·hm^-2), conventional urea (CU, 180 kg N·hm^-2), and four polymer-coated urea fertilization levels, i.e., 1.0CRU, 0.9CRU, 0.8CRU, 0.7CRU, which represented 0, 10%, 20% and 30% reduction of fertilizer inputs relative to CU, respectively. Leachate was collected at the soil depth of 60 cm using field leakage pool method. Nitrogen leaching peaked shortly after fertilization, implying that measures should be taken to prevent N leaching in the early period. Nitrogen losses from leaching were 42.3 kg N·hm^-2 for 0.8CRU, and by 37.7 kg N·hm^-2 for 0.7CRU, significantly lower than the leaching in CU (53.9 kg N·hm^-2). Nitrogen leaching in 0.7CRU was significantly lower than that in 1.0CRU (51.3 kg N·hm^-2). 11.9%-13.5% of the fertilizer N was lost via leaching across the six treatments with comparable N loss rates. Rice yields, N utilization efficiency and N harvest index were significantly higher in 0.8CRU and 0.7CRU relative to CU. Our findings suggested that the use of CRU would permit a reduction in N application by 20%-30%, which could maintain the rice yield and obtain a reduction in N leaching.

Spatio-temporal evolution of traditional soybean planting structure in Songnen Plain, China in 1996-2016

LIU Hang, WU Wen-bin, SHEN Ge, HUANG Qing

2018, 29(10):  3275-3282.  doi:10.13287/j.1001-9332.201810.011

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Under the impacts of genetically modified soybean, the planting area of traditional soybean in China has fallen sharply. Understanding the traditional soybean planting structure and dynamics in the main soybean producing areas is of great significance to China’s soybean import and export trade and safeguarding national food security. With the Landsat TM/OLI remote sensing images from 1996 to 2016, we extracted the spatial distribution information of soybean planting using random forest (RF) method based on remote sensing (RS) and geographic information system (GIS) techniques and analyzed the spatiotemporal evolution characteristics of soybean planting structure in the Songnen Plain using landscape pattern index. The results showed that the soybean planting area in the Songnen Plain was fluctuating during 1996-2016. Among the area conversion with other land-use types, the interchanges between soybean and other crop lands were the most obvious. The proportion of soybean patch area to the total crop area increased first and then decreased, while the patch density index and the resolution index decreased first and then increased. In conclusion, the spatiotemporal evolution of the traditional soybean planting structure in the Songnen Plain showed the characteristics of fluctuation in planting area, increase in fragmentation, and discrete spatial distribution. The domestic and foreign markets as well as policy guidance were the important factors afecting the traditional soybean planting structure.

Effects of different mulching modes on soil nitrate concentration and grain yield of Linum usitatissimum in dry land

GAO Yu-hong, WU Bing, NIU Jun-yi, GUO Li-zhuo, LIU Hong-sheng, CUI Hong-yan, LI Chun-chun, KE Jia

2018, 29(10):  3283-3292.  doi:10.13287/j.1001-9332.201810.022

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To investigate soil NO₃^--N dynamics and yield increasing effect of mulching planting for Linum usitatissimum (oil flax) in semi-arid Loess Plateau, we examined the effects of three mul-ching modes (whole field plastic mulching and micro ridges with soil cover and bunch-seeding; whole field plastic mulching with soil cover and bunch-seeding; and straw mulching with strips) on seed yield and distribution of soil NO₃^--N during the main growth periods of oil flax, with the conventional planting model as control (CK) in 2015 and 2016. Results showed that the average yield under mulching modes was increased by 56.1% (2015) and 22.7% (2016). The treatment of whole field plastic mulching with soil cover and bunch-seeding had the highest grain yield. Mulching treatments significantly increased soil water content. Soil water content was increased first and then reduced in the whole growth stage of oil flax. The soil NO₃^--N content was gradually decreased during the oil flax growth process. In both years, NO₃^--N content in 0-40 cm soil depth under mul-ching treatments were increased by 3.1%-18.6% (2015) and 5.1%-16.4% (2016) at budding stage of oil flax, respectively. The whole field plastic mulching with soil cover and bunch-seeding treatment showed the larges increases across all treatments. In 2015, NO₃^--N accumulation in 0-100 cm soil depth between the flowering and maturity stages of oil flax were increased by 10.2%-22.2% and 8.6%-21.4%, respectively. Especially during the more rainfall period of maturity stage, NO₃^--N accumulation in 0-40 cm soil depth was significantly enhanced by 3.3%-4.9% than that in 40-100 cm soil depth. It indicated that more rainfall could slow down the migration of NO₃^--N to the lower layer under the mulching modes in the maturity stage. In 2016, high temperature and drought at late growth stages had a great influence on oil flax growth. The NO₃^--N accumulation in 0-100 cm soil depth at the maturity stage was increased by 6.6%-18.0%. There was significant correlation between NO₃^--N content and grain yield during the main growth stages of oil flax. In conclusion, the whole field plastic mulching with soil cover and bunch-seeding treatment was the most appropriate way of oil flax production in arid and semi-arid area.

Effects of vertically rotary sub-soiling tillage on water utilization and yield of potato in semi-arid area of northwest China

ZHANG Xu-cheng, MA Yi-fan, YU Xian-feng, HOU Hui-zhi, WANG Hong-li, FANG Yan-jie

2018, 29(10):  3293-3301.  doi:10.13287/j.1001-9332.201810.023

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To examine the effects of vertically rotary sub-soiling tillage (VRT) on stage water consumption, individual and population development, yield, water use efficiency, and economic profit of potato is helpful to find the optimized tillage method which could increase crop drought-resistant, yield, and resource use efficiency. With randomized block design, the field experiment involved in three treatments, 1) vertically rotary sub-soiling tillage for 40 cm depth (VRT), 2) deep loosing tillage for 40 cm (DLT), and 3) rotary tillage for 15 cm (TT). The soil water storage in 0-200 cm soil profile in different growth stages of potato, foliar SPAD value, leaf area index (LAI), plant dry matter content, tuber yield were recorded, and stage water consumption, water use efficiency (WUE), tuber commodity rate, tuber commodity yield, and profit were calculated, to investigate the effects of VRT on production efficiency and economic profit. The results showed that VRT increased water consumption in flowering and tuber expanding stage by 46.7, 35.7 mm in 2016 and 27.2, 47.3 mm in 2017, as compared with DLT and TT. Based on the increased stage water consumption, foliar SPAD value, dry matter content, and LAI increased significantly, suggesting the VRT promoted individual and population development. The higher individual and population biomass resulted in significant increase in tuber yield which increased by 156.8%, 47.8% in 2016 and 24.8%, 41.0% in 2017 respectively, as compared with DLT and TT. Accordingly, WUE increased by 92.3%, 19.2% and 18.9%, 26.6%. The tuber commodity yield and profit significantly increased in VRT treatment, as well as the profit which reached to 12631.9, 11019.1 yuan·hm^-2 in 2016 and 29498.3, 18245.5 yuan·hm^-2 in 2017, respectively. VRT promoted potato water consumption in flowering and tuber expanding stages, resulted in significant increases of foliar SPAD value, plant dry matter, and LAI, with positive consequences on the tuber yield, WUE, as well as the tuber commodity yield and economic profit. These indicated that the VRT was helpful to increase potato drought resistance, yield and profit, and thus would be the appropriate tillage method on semi-arid northwest Loess Plateau.

Effects of calcium fertilizer application on absorption and distribution of nutrients in peanut under salt stress

SHI Xiao-long, ZHANG Zhi-meng, DAI Liang-xiang, ZHANG Guan-chu, CI Dun-wei, DING Hong, TIAN Jia-ming

2018, 29(10):  3302-3310.  doi:10.13287/j.1001-9332.201810.026

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In order to solve the problems of nutrient absorption and accumulation and provide theoretical basis for rational amount of calcium fertilization of peanut in saline land, the effects of calcium fertilizer application on absorption and accumulation of nutrients including nitrogen, phosphorus, potassium, calcium and magnesium in peanut under salt stress were examined. Using ‘Huayu 25’ as experimental material, four Ca levels [T₁ (0), T₂ (75), T₃ (150) and T₄ (225) kg·hm^-2 CaO] were set under 0.3% salt stress in a pot experiment. The results showed that nutrient contents in peanut followed the order of nitrogen > potassium > calcium > phosphorus > magnesium. At the seedling stage, leaves were the absorption center of nitrogen and calcium, while stems were the center of phosphorus, potassium and magnesium, with nearly half of nutrient accumulation being distributed in the corresponding growth center. At mature stage, the absorption centers of nitrogen, phosphorus and potassium were transferred to pod. The accumulation of nitrogen and phosphorus in seed kernel reached to 72.3%-78.9%. The absorption centers of calcium and magnesium was still in the leaves and stems, with a distribution ratio of 49.8% and 32.6%, respectively. Salt stress significantly inhibited nutrient absorption and distribution in peanut, especially decreased the nitrogen accumulation in leaves and seed kernels. However, salt stress increased the magnesium accumulation in pod. Exogenous calcium application had significant positive effect on absorption and accumulation of nitrogen, phosphorus, calcium and magnesium in different organs of peanut under salt stress. It had significant adjustment on phosphorus accumulation in seed kernel, which was increased by more than 50%. Appropriate calcium content could significantly promote the peanut nutrient absorption and accumulation under salt stress and improve the distribution ratio of nitrogen, phosphorus, potassium in mature pods of peanut. According to the responses of nutrient absorption and distribution, the optimized application amount for calcium fertilizer under 0.3% salt stress was 150 kg·hm^-2 CaO.

Effects of mulching duration on PAEs accumulation in soil and tobacco leaves in Zunyi, China

ZHANG Xin, LI Zhi-tao, CHEN Qiu-shi, XU Li, SUN Guang-jun, ZHANG Shi-xiang, JIAO Jia-guo

2018, 29(10):  3311-3318.  doi:10.13287/j.1001-9332.201810.039

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We examined the effects of the duration of plastic film mulching on the accumulation of phthalate (PAEs) in soils and tobacco to determine the soil pollution distribution characteristics of PAEs under continuous mulch use and the enrichment status in tobacco leaves. Samples of both soils and tobacco leaves were collected from Lianqian Village and Shawan Village of Zunyi. Gas chromatography-mass spectrometry (GC-MS) was used to determine the contents of six preferentially controlled PAEs in samples. The results showed that the six ΣPAEs in all soil and tobacco samples were (2.66 ±0.60) and (3.58±0.64) mg·kg^-1, of which the content of DEHP was the highest, followed by DBP, with the sum of those two accounting for 92.7% and 88.9% of ∑PAEs in the soil and tobacco, respectively. The detection rates of DEHP, DBP, DEP, and BBP were 100.0%. The detection rate of DMP was slightly lower, and that of DnOP was the lowest. The content of PAEs in soils and tobacco leaves significantly increased with the increases of mulching years. In the 1-8 years of film mulching, the increases of PAEs were more obvious and tended to be gentle in the later stage. The content of PAEs in soil and tobacco leaves had significant positive correlation with the years of film mulching, indicating that the increase of film mulching years could significantly promote the accumulation of PAEs. There was no significant correlation between the ∑PAEs accumulation between tobacco leaves and soil.

Dynamics of growth and nitrogen accumulation and utilization of young apple trees

TIAN Ge, WANG Fen, XU Xin-xiang, JIA Zhi-hang, GE Shun-feng, JIANG Yuan-mao

2018, 29(10):  3319-3325.  doi:10.13287/j.1001-9332.201810.024

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Taking 6-year-old Yanfu3/SH6/Malus hupehensis Rehd. as the test material, the dynamics of plant growth and nitrogen (N) accumulation under seven periods from germination stage to fruit maturity stage were examined by destructive analysis. The absorption, utilization, and distribution of fertilizer N were studied by ¹⁵N isotope tracer technique to clarify the N accumulation dynamics of apple trees and the maximum efficiency period of fertilizer N, and to provide theoretical basis for scientific application of N fertilizer. The results showed that the net accumulation of dry matter was 4.51 kg in germination stage (March 25) to fruit maturity stage (210 d after budbreak), with fruit accounting for 66.5%, the leaves and new shoots accounting for 20.2%, and the perennial organs accounting for 13.3%. The dry matter accumulation in 30-60 d after budbreak was the fastest, accounting for 42.9% of the whole treatment period. The fruit dry matter accumulation in 120-180 d after budbreak was the fastest, which accounted for 70% of the whole treatment period. The total N accumulation of the plant was 29.1 g, which increased rapidly in the 30-60 d and 120-180 d after budbreak by 7.2 g and 12.8 g, respectively accounting for 24.7% and 44% of the whole treatment period. The N accumulation of leaves and new shoots was the fastest in 0-60 d after budbreak, which accounted for 69.1% of the whole period. The N accumulation of fruit was the fastest in 120-180 d after budbreak, accounting for 60.8% of the whole period. The N accumulation of the perennial organ decreased first and then increased, and reached the lowest level at 60 d after budbreak. The ¹⁵N utilization rate of plant differed significantly in different periods which was at a high level in 30-60 d,120-150 d and 150-180 d after budbreak with 2.3%, 4.1% and 4.0% respectively. The ¹⁵N distribution rate in perennial organs in each period showed a high level, that of the new born organ increased first and then decreased which reached the highest level of 38.4% in 30-60 d after budbreak. The fruit reached the highest in 120-150 d and 150-180 d after budbreak by 15.0% and 16.6% respectively. Therefore, the key period of N accumulation in leaves and shoots was 30-60 d after budbreak, and that in fruit was 120-180 d after budbreak. The period with maximum efficiency for fertilizer N was at 30-60 d and 120-180 d after budbreak.

Effective supply of eco-product and its influence factors at provincial scale of China from the perspective of supply-side reform

ZHENG Jing, YU Hao

2018, 29(10):  3326-3336.  doi:10.13287/j.1001-9332.201810.010

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Eco-product is scarce product with consequences on human health, economy and society all over the world. In order to understand the effective supply of eco-product and figure out its law of scale efficiency, panel data from 2004 to 2015 with labor force, capital, resource, and energy source was carefully selected as the input variables and GDP, sustainable product, and undesirable output as the output variables, the scale efficiency and its differences of effective supply of eco-product in China were measured in this study. SBM-Undesirable model, Theil index, and the model of Tobit were used to analyze the driving factors. The results showed that there was a downward trend in scale efficiency of China’s eco-products before 2011, and an upward trend with obvious inter-regional differences since 2012. The influence factors of supply efficiency of eco-product greatly varied among different regions. Overall, some factors had negative influences, including the values of economic development level, industrial structure (the proportion of secondary industry’s increase in GDP), science and technology input, financial capital input (the proportion of environment pollution control investment in GDP), energy consumption structure (the proportion of coal consumption in overall energy consumption), and agricultural non-point source pollution. Some factors had positive influences, such as eco-space and foreign trade structure. In Eastern China, factors such as industrial structure, science and technology input, financial capital, energy consumption structure and agricultural non-point source pollution had negative impacts, while the factors of economic development level, eco-space and foreign trade structure had positive impacts. In Northeast China, the factors of economic development level, financial capital, agricultural non-point source pollution and foreign trade structure had negative impacts, while the factors of industrial structure, science and technology input, energy consumption structure and eco-space had positive impacts. In Central China, the factors of economic development level, science and technology input, financial capital, energy consumption structure, agricultural non-point source pollution and eco-space had negative impacts, while the factors of industrial structure and foreign trade structure had positive impacts. In Western China, the factors of industrial structure, energy consumption structure, and agricultural non-point source pollution had negative impacts, while the factors of economic development level, science and technology input, financial capital, eco-space, and foreign trade structure had positive impacts. Based on further theoretical analysis of above-mentioned empirical measurement, some poli-cy implications were put forward for effectively improving the efficiency of eco-product supply from the angle of supply-side reforming, which included emphasizing the transitions mode of sustainable economy, optimizing ecosystem structure, and managing ecosystem as a whole according to natural laws.

Assessment of ecological conditions over China’s coastal areas based on land use/cover change

MENG Zi-qi, LONG Ling-bo, SHE Qian-nan, CHENG Dan-yang, LIU Min

2018, 29(10):  3337-3346.  doi:10.13287/j.1001-9332.201810.016

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Studying the changes of land use and its impacts on ecological condition in coastal areas is of great significance for understanding the evolution of the regional ecological conditions and even global change. In this study, the study area encompassed 10 provincial administrative units of China’s coastal areas, covering a total of 56 cities. Based on the land use and land cover data in 1980, 1990, 1995, 2000, 2005, 2010 and 2015 and the corresponding elevation data, we assessed ecological conditions and its temporal dynamic evolution and spatial differentiation characteristics with the ecological grade index method. The effects of the elevation differentiation and land-sea gradient on the ecological condition in China’s coastal areas were analyzed. The results showed that the ecological conditions of China’s coastal areas were basically stable and deteriorated on the whole although partially improved from 1980 to 2015. With Hangzhou Bay as a boundary-belt, ecological conditions in southern parts were better than that in the northern parts. The ecological grade index differed significantly with the variation of elevation. The areas with elevation below 10 m were in rela-tively poor ecological condition, and the regions below 30 m had the most obvious changes of ecological conditions. Moreover, the ecological conditions increased with elevation, with a gradual turnaround trend of improvement at above 400 m. There was a gradient characteristic of the ecological grade index in China’s coastal areas, showing a high-low-high pattern from land to sea. Furthermore, the maximum value of ecological condition changes appeared at a distance of 10 km to the coastline, and the values decreased with the increasing of distance to the coastline.

Assessment of the eco-environmental quality in the Nanweng River Nature Reserve, Northeast China by remote sensing

LIU Pan, REN Chun-ying, WANG Zong-ming, ZHANG Bai, CHEN Lin

2018, 29(10):  3347-3356.  doi:10.13287/j.1001-9332.201810.014

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Scientific and rapid assessment of the ecological environment quality based on remote sensing can provide basis for regional protection, management and planning. In this study, using Landsat TM/OLI/TIRS in 1990, 2000 and 2015 as data sources, four indices including the wetness component of the tasseled cap transformation (WET), normalized difference vegetation index (NDVI), normalized difference built-up and soil index (NDSI), and land surface temperature (LST) were derived, with the weights being determined by principal components analysis (PCA). Remote sensing ecological index (RSEI) was used to evaluate the eco-environmental quality of Nanweng River Nature Reserve from 1990 to 2015. Results showed that RSEI was an effective indicator for evaluating spatio-temporal dynamics of eco-environmental quality. From 1990 to 2015, the mean value of RSEI of Nanweng River Nature Reserve increased from 0.55 to 0.83, the proportion of area with excellent and good levels of RSEI trended to increase, probably due to the increase of forests at those levels. Meanwhile, 91.4% of the total land area in the reserve had an improved eco-environmental quality. Such improvement was attributed to the establishment of the reserve and implement of a series of engineering and non-engineering protection measures. In the north of core area and buffer area, decrease of eco-environmental quality was due to forest fires which destroyed a large area of forest vegetation. In the road side and southeast of the experimental area, intensified human activities led to the decrease of regional eco-environmental quality.

Landscape ecological planning of coastal industrial park based on low impact development concept: A case of the second coastal industrial base in Yingkou City, Liaoning Province, China

LI Sui, XIU Dai-xi, SHI Tie-mao, ZHOU Shi-wen, FU Shi-lei, YU Chang

2018, 29(10):  3357-3366.  doi:10.13287/j.1001-9332.201810.009

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Low impact development (LID) of industrial parks is an important component in the construction of China’s sponge cities. We compared the methods of optimizing ecological spatial structure for rain and flood control in industrial parks, via analyzing the influence of landscape pattern on hydrological process. Firstly, according to the hydrological and geological conditions of the coastal area, the landscape pattern of the industrial park was optimized, with the water corridor system being structured and green patches being integrated. Then, the reasonable spatial allocation for the ecological infrastructure of the industrial park was realized, with the rain and flood control areas being divided based on the characteristics of the underlying surface. The runoff control indices of different control areas were determined, and the LID technical measures of different landscape nodes were selected. The results showed that the landscape pattern optimization strengthened landscape connectivity by constructing the ecological network within the industrial park. The runoff control rate of the park increased from 45% to 70% through the combination of various LID technologies, with the pervious pavement, submerged green space, rainwater garden, wet pond and grass ditch accounting for 1.3%, 1.9%, 0.2%, 0.2% and 0.1% of the total area, respectively. This study could provide new ideas and methods for the low impact development and construction of coastal industrial parks.

Construction of ecological network using morphological spatial pattern analysis and minimal cumulative resistance models in Guangzhou City, China

YANG Zhi-guang, JIANG Zhi-yun, GUO Cheng-xuan, YANG Xiao-jing, XU Xiao-jun, LI Xiao, HU Zhong-min, ZHOU Hou-yun

2018, 29(10):  3367-3376.  doi:10.13287/j.1001-9332.201810.019

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Construction of ecological network is important for improving urban ecological environment under the scenarios of rapid urbanization. We extracted the core area with good connectivity as the ecological sources with the methods of morphological spatial pattern analysis (MSPA) and landscape index with Guangzhou City as the study area. The ecological network was then constructed by minimal cumulative resistance (MCR) model and was quantitatively analyzed by gravity model and connectivity indices. After that, an optimized ecological network was finally constructed. The results showed that ten core patches could be used as ecological sources. In addition, eighteen important corridors as well as twenty-seven general corridors were identified, which were mainly distributed in the northeast part of the city. Five more ecological sources and thirteen more planning corridors were suggested under the optimized ecological network. Our results indicated that forests were the main composition of ecological corridors. The appropriate width for the important corridor and planning corridor was 60-100 m and 30-60 m, respectively. Our results provide scientific guidance for designing urban ecological network.

Influences of shale gas well-pad development on land use and vegetation biomass in a shale gas mining area

CHEN Hong-kun, DU Xian-yuan, GUO Yu, ZHANG Xin-yu, WU Qian, WANG Qiu-bing, HE Ji-an, MA Liang

2018, 29(10):  3377-3384.  doi:10.13287/j.1001-9332.201810.008

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It is not clear how shale gas mining would affect land use change and vegetation biomass in the villages and farmlands where was substantially influenced by human activities around the well-pads of the shale gas mining areas in Sichuan Province. Using remote sensing and image interpretation in 2012 and 2017 and in situ vegetation investigation data in 2017, we analyzed the changes of land use and biomass in well-drilling fields and buffer zones and further examined the extent affected by well-drilling and subsequently vegetation biomass loss. The results showed that shale gas mining had converted 93.81 hm² of land to mining land from 2012 to 2017, among which almost half (48.6%) was dry land (about 45.61 hm²), 17.2% forest land (16.13 hm²), 11.0% residential land (10.28 hm²), and 11.1% shrubland (10.39 hm²). The extent affected by well-drilling ranged from 0 to 50 m at the early stage, which decreased at the stage of stable gas production. As a result of well-drilling, over 2477.53 t of vegetation biomass was lost, of which 71.6% being accounted for by the well-drilling fields and the remaining (28.4%) being caused by road construction and temporary land use. Direct occupation of dry land and forested land by shale gas well-pads mainly caused land use changes and biomass losses in this shale gas mining area. Our results have implications for ecological environment management and shale gas sustainable mining in this area.

Analysis of carbon sink of steel slag in China

LIU Li-li, WANG Jiao-yue, BING Long-fei, LING Jiang-hua, XU Meng, XI Feng-ming

2018, 29(10):  3385-3390.  doi:10.13287/j.1001-9332.201810.015

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Under the context of the elevated greenhouse gases, how to reduce carbon emissions and increase carbon absorption is the focus of current research on climate change. Based on data of Chinese crude steel production from 1963 to 2016 and greenhouse gas inventory method, we established steel slag carbon sequestration calculation method. The steel slag carbon sequestration from 1963 to 2016 was estimated and the uncertainty analysis was made. The results showed that annual carbon sink of steel slag in China increased from 3.75×10³ t C in 1963 to 1359.32×10³ t C in 2016. The steel slag accumulative carbon sink was 15×10⁶ t C, with about ±30.4% total uncertainty during 1963-2016. The annual carbon sink of steel slag was composed of carbon sink of the current year steel slag and the previous years. Due to the dense structure and low carbonation rate of steel slag, the carbon sink of the current year was small, accounting for 37% of the total, while that of the previous years were relatively large, accounting for 63% of the total. Although annual carbon sink of steel slag was small, the long-term accumulative carbon sink for steel slag was very considerable, which could not be ignored. Future research should refine carbonation rate of steel slag under diffe-rent environmental conditions to reduce steel slag carbon accounting uncertainty, promote the deve-lopment of carbon capture and storage (CCS) technology with steel slag as raw material to increase effective carbon sequestration, which would provide scientific support for China’s international negotiations on climate change.

Spatio-temporal dynamics of ecosystem service value of green land in Shenyang, Northeast China

CHEN Hong-wei, XU Jing, LIU Na, HONG Jiao-jiao, QI Shu-yan, YUAN Hao

2018, 29(10):  3391-3397.  doi:10.13287/j.1001-9332.201810.013

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Urban green land is an important component of urban natural ecosystems, with critical ecosystem service functions. Based on the land use data of Shenyang in 2005, 2010 and 2015, this study estimated ecosystem service value (ESV) according to “equivalent value per unit area of ecosystem services for various ecosystems in China” and then analyzed its spatio-temporal characteristics and change rate. The results showed that arable land area significantly reduced by 3.5% from 2005 to 2010 and 10.9% from 2010 to 2015, respectively. Wood land area increased slightly, and the area of meadow increased by 17.2%. The ESV of green land in Shenyang increased from 11.76×10⁸ yuan in 2005 to 23.48×10⁸ yuan in 2010, and then decreased to 11.29×10⁸ yuan in 2015. The annual change of ESV showed significant difference among different districts, with the highest occurring in Yuhong, Shenbei and Heping districts. The coefficient of variation (CV) was 64.9%, 60.4% and 40.8%, respectively. The ESV of green land varied significantly among diffe-rent districts, with higher values occurring in Huanggu, Shenbei and Dongling districts. Soil conservation function had the highest ESV, accounting for 15% of the total ESV. The food production function had the lowest ESV. The changes of ESV in Shenyang might be attributed to the urban expansion, agricultural land conversion, and green space construction.

Effects of long-term fertilization on arbuscular mycorrhizal fungal community in lime concretion black soil

MA Yu-ying, ZHANG Huan-chao, XIANG Xing-jia, WANG Dao-zhong, GUO Xi-sheng, GUO Zhi-bin, SUN Rui-bo, CHU Hai-yan

2018, 29(10):  3398-3406.  doi:10.13287/j.1001-9332.201810.035

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In agroecosystem, arbuscular mycorrhizal fungi have mutually beneficial symbiosis with roots of many crops. Meanwhile, this special fungal community is also affected by agricultural mana-gements such as fertilization. The objective of this study was to investigate the effects of long-term fertilization managements (no fertilizer, chemical fertilizer, chemical fertilizer combined with straw, chemical fertilizer combined with manure) on arbuscular mycorrhizal fungal community (AM fungal community) in lime concretion black soil, and to identify the indicator species in each fertilization regime. The most dominant arbuscular mycorrhizal fungal phyla in lime concretion black soil were Archaeosporaceae, Diversisporaceae, Gigasporaceae, Claroideoglomeraceae, Glomeraceae and Paraglomeraceae. The genus Paraglomus was strongly and significantly associated with the application of chemical fertilizer and organic fertilizer. Compared with the control, long-term application of chemical fertilizer greatly changed AM fungal community structure and resulted in the decrease of AM fungal diversity, and the addition of wheat straw further decreased the diversity, while the addition of manure could alleviate diversity loss resulted from chemical fertilization. Soil pH and dissolved organic carbon (DOC) were the main factors affecting the changes of AM fungal community. In summary, long-term application of chemical fertilizer combined with different organic materials had different impacts on soil AM fungal community structure and diversity. The combination of chemical fertilizer and manure would be more conducive to the maintenance of AM fungal diversity.

Screening of bacteria that antagonize the main pathogen fungi of apple replantation disorders from anaerobic fermented fluid of organic material and its inhibitory effect

LIU Li-ying, LIU Ke-xin, ZHU Hao, CHI Xiao-li, XU Chao, ZHANG Xiao, LIU Wei-wei, JIN Xiao, SUN Zhong-tao, MAO Zhi-quan

2018, 29(10):  3407-3415.  doi:10.13287/j.1001-9332.201810.036

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Anaerobic fermented organic materials fluid (AFOF) could alleviate apple replant diseases. In this study, bacteria from AFOF was screened which could antagonize the main pathogenic fungi (Fusarium solani, F. proliferatum, F. oxysporum, F. moniliforme). The effects of the antagonistic bacteria were verified by pot experiment. The results showed that AFOF could significantly inhibit the pathogenic fungi growth and reproduction. Four strains (L11, L12, L13, L14) with strong inhibition activity were obtained from AFOF by the confrontation test, with the highest inhibitory rate being up to 57.3%. All the four strains were Bacillus, with no obvious antagonism each other. Both antagonistic bacteria and methyl bromide fumigation could promote the biomass of Malus hupenhensis seedling compared with continuous cropping soil. Methyl bromide fumigation led to the best growth of M. hupenhensis seedling. The antagonistic bacteria cloud improve root activity, with root length and root tip number increased by 25.1% and 70.9%, respectively. Compared with the continuous cropping soil, antagonistic bacteria and methyl bromide fumigation effectively decreased soil fungi by 71.2% and 64.2%, respectively. Treatment with antagonistic bacteria increased soil bacteria and soil actinomycetes by 48.0% and 140.2%, respectively, indicating that soil microbial community was transformed to “bacteriatype”. Treatment with methyl bromide fumigation could significantly reduce soil bacteria and soil actinomycetes, suggesting the antagonistic bacteria could inhibit the growth of pathogenic fungi in soil.

P absorption and removal mechanism of new Salix clone (A42)on eutrophic water with different P concentrations

CAI Ze-yu, ZHANG Jian-feng, CHEN Guang-cai, ZHANG Han-dan, SUN Shi-yong, LI Xiao-gang, QIN Guang-hua

2018, 29(10):  3416-3424.  doi:10.13287/j.1001-9332.201810.037

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Phosphorus is the necessary element for plant growth, and its concentration is one of the main indices for water eutrophication. Hence, it is significant to understand how woody plants purify phosphorus in eutrophic water. The purpose of this study is to reveal the P absorption and removal mechanism of Salix matsudana in eutrophic water with different P concentration. We selected new S. matsudana clone (A42) as experimental material and set three levels of P concentration (low P: 0.1, 0.2 mg·L^-1; medium P: 1.0, 2.0 mg·L^-1, high P: 10.0 mg·L^-1), and the floating bed hydroponic experiment was conducted at the greenhouse from July to September, 2017. We found that S. matsudana efficiently removed P in water (removal rate >79% in 21 days). There was a positive correlation between the removal quantity and P concentration in the water. The removal ratio rose at first and then fell with increasing P. Owing to the purification of S. matsudana, the P concentrations ranging from 0.1 mg·L^-1 to 1.0 mg·L^-1 were reduced to minimum threshold concentration of eutrophication (0.016-0.032 mg·L^-1) in seven days. The percentage of phosphorus input in water that assimilated by S. matsudana ranged from 29.0% to 66.9%. The quantity and ratio of assimilated P were respectively positive and negative relation with P concentration. Salix matsudana adapted to eutrophic water with different P concentrations and normally grew during experiment period, with root-shoot ratio being significantly increased with decreases of water P concentrations. The characteristic of phosphorus distribution in plant organs was: stem> leave>root, while the translocation factors (TF) of nitrogen and phosphorus were both greater than 3. When S. matsudana grew in eutrophic water with high phosphorus concentration, the TF of nitrogen and phosphorus significantly increased to 4.53±0.24 and 4.92±0.62 respectively. Our results indicated that S. matsudanais could purify the eutrophic water and it could normally grow. New clone of S. matsudana could effectively absorb phosphorus in the water and accumulated it in the stem, which could reduce secondary pollution. In conclusion, S. matsudana could be used for a short-term treatment on the eutrophic water with low P concentration, while for the long-term treatment it is adapted to eutrophic water with high phosphorus concentrations.

Effects of vegetative filter strip on overland flow nitrogen and phosphorus intercepting under different inflow conditions

SHE Dong-li, A Limu A Bulaiti, CHEN Qian, HAN Xiao

2018, 29(10):  3425-3432.  doi:10.13287/j.1001-9332.201810.017

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The vegetative filter strips can effectively intercept erosion of water and sediment on the slope, with huge potential to prevent and control soil erosion and agricultural non-point source pollution. A series of muddy water scouring experiments under different inflow conditions in the indoor soil trays were conducted to investigate the effects of vegetative filter strip (VFS) on intercepting nitrogen (N) and phosphorus (P) under different inflow conditions and its internal hydrological responses. The results showed that the VFS could effectively intercept N and P in the runoff. When the inflow was 200, 400, 600 L·h^-1, the intercepting rates were 74.9%, 62.0%, 58.3% for N and 85.0%, 75.6%, 72.0% for P, respectively. The best intercepting effect occurred at the lower inflow rates. Different inflow N and P concentrations had no significant effect on N and P interception efficiency. Under different inflow conditions, the intercepting rates of N and P by VFS increased with the increases of Froude value with a significant linear positive correlation. However, there were linear negative correlations between the intercepting rate and resistance coefficient, shear stress and stream power. The relationship between the N and P intercepting rates and shear stress was the best among others, and the N and P intercepting rates could be well predicted by a formula containing shear stress.

Effects of ethylene and NO on AsA-GSH in lotus under cadmium stress

YUAN Man, XU Ying-chun, NIU Ye-qing, ZHOU Hui, AN Yi-lin, JIN Qi-jiang, WANG Yan-jie

2018, 29(10):  3433-3440.  doi:10.13287/j.1001-9332.201810.033

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Under the background of Cd (50 μmol·L^-1) stress, we added ethylene precursor ACC (100 μmol·L^-1), ACC + nitric oxide synthase (NOS) inhibitor L-NNA (200 μmol·L^-1), ACC + nitrate reductase (NR) inhibitor Tu (1 mmol·L^-1), ACC + nitric oxide (NO) scavenger PTIO (200 μmol·L^-1), NO donor SNP (500 μmol·L^-1), SNP + ethylene signal inhibitor STS (100 μmol·L^-1) to examine their effects on the damage degree of leaves and response mechanisms of AsA-GSH cycle in lotus ‘Weishanhuhonglian’. Results showed toxic symptom of lotus leaves under Cd stress. The relative conductivity, malondialdehyde (MDA), as well as ascorbic acid (AsA) and glutathione (GSH) contents were significantly increased, but the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) were obviously decreased. Compared with Cd stress, adding ACC significantly increased the damage area of lotus leaves, decreased activities of the above-mentioned four antioxidant enzymes and increased AsA and GSH contents. SNP aggravated the toxic symptom of lotus leaves and decreased GR and MDHAR activities. PTIO significantly relieved the toxic symptom of leaves, increased activities of APX, GR, MDHAR and DHAR, but decreased AsA and GSH contents compared with Cd and ACC treatment. However, the effects of L-NNA and Tu were not as obvious as PTIO’s. In comparison with Cd and SNP treatment, STS relieved the toxic symptom of leaves, increased APX, GR, MDHAR and DHAR activities, and decreased AsA and GSH contents. Taken together, these results showed the synergistic effects of ethylene and NO in regulating lotus responses to Cd stress through AsA-GSH cycle.

Photosynthetic fluorescence characteristics of six macroalgae species in seaweed beds of Gouqi Island, Zhejiang, China

ZHANG Shou-yu, XIANG Chen, ZHOU Xi-jie, LIU Shu-rong, CHENG Xiao-peng, WANG Kai

2018, 29(10):  3441-3448.  doi:10.13287/j.1001-9332.201810.031

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The study of photosynthetic fluorescence characteristics of algae is important for the analy-sis of photosynthesis and carbon sequestration of algae. In July 2017, six common species of macroalgae found in Gouqi seaweed beds were collected, including Ulva pertusa, Cladophora stimpsonii, Grateloupia livida, Sargassum thunbergii, Polysiphonia urceolata, and Hizikia fusifarme. In the field, the maximal quantum yieids of photosystemⅡ(F_v/F_m) and rapid curves (RLCs) were mea-sured by using pulse-amplitude modulated fluorometer (Diving-PAM). The results showed that the measured maximal quantum yields of U. pertusa, C. stimpsonii, G. livida, S. thunbergii, P. urceolata, and H. fusiforme were 0.702, 0.704, 0.457, 0.618, 0.421 and 0.567, respectively. The F_v′/F_m′ of six species were in order of C. stimpsonii>U. pertusa>S. thunbergii＞H. fusiforme＞G. livida＞P. urceolata. The difference between each species and significant difference was found in U. pertusa, C. stimpsonii, and H. fusiforme. H. fusiforme, S. thunbergii and U. pertusa had higher P_m and α than other species, indicating their higher photosynthetic capacity and better adaptation in higher light condition. However, G. livida had higher α but lower I_k, indicating G. livida had higher photosynthetic capacity in low light condition. In a word, differences of photosynthetic capacity and light intense tolerance between the three phyla of macroalgae were found and we suggested H. fusiforme, S. thunbergii and U. pertusa had stronger photosynthetic capacity and light intense tolerance. Our results could provide theoretical basis for the seaweed bed conservation and carbon sequestration of macroalgae.

Gut bacterial community diversity in Carposina sasakii and Grapholitha molesta

LI Yan-yan, SUN Li-na, TIAN Zhi-qiang, HAN Hai-bin, ZHANG Huai-jiang, QIU Gui-sheng, YAN Wen-tao, YUE Qiang

2018, 29(10):  3449-3456.  doi:10.13287/j.1001-9332.201810.034

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To clarify the community structure and diversity of larval gut bacteria in Carposina sasakii and Grapholitha molesta, the V4 regions of the 16S rDNA genes of intestinal bacteria of C. sasakii and G. molesta larvae which fed by golden delicious apple, were amplified and sequenced by Illumina HiSeq technique. The results showed that a total of 229043 high quality reads of gut bacteria in C. sasakii larvae were obtained and clustered to 2112 OTUs, which were annotated into 27 phyla, 65 classes, 124 orders, 205 families and 281 genera. 240389 reads of G. molesta were produced and clustered to 957 OTUs, which were annotated into 22 Phyla, 46 Classes, 89 Orders, 145 Families and 180 Genera. C. sasakii was dominated by the Proteobacteria (87.98%±5.29%), Firmicutes (3.91%±1.19%), Actinobacteria (1.04%±0.47%), and G. molesta was mainly dominated by Proteobacteria (50.06%±19.56%), Firmicutes (32.02%±8.48%) and Cyanobacteria (25.24%±10.28%). All of Phylum, Class, Order, Family, Genus, Species of the bacteria were significantly different between C. sasakii and G. molesta. Those results suggested that the gut bacteria community in these two fruit-boring pests was notably different, although they were both fed by apple fruit. The bacteria communities were more complex in C. sasakii than in G. molesta, which might account for different feeding and digestion mechanisms. The results could lay a foundation to reveal the association of the intestinal bacteria with these two fruit borers.

Seasonal variation in trophic structure of fish community in Minjiang Estuary based on stable isotope technique

SHI Yan, HE Xiong-bo, LI Jun, SHEN Chen, FENG Chen, GUO Jun-hong, ZHAO Chun-xu, KANG Bin

2018, 29(10):  3457-3463.  doi:10.13287/j.1001-9332.201810.032

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To study the trophic structure of fish community in Minjiang Estuary, we measured the carbon and nitrogen stable isotope ratios (δ¹³C and δ¹⁵N) of common fish species sampled in winter (January), spring (May), summer (August) and autumn (November) of 2015 by trawling, as well as seven quantitative metrics (ratios range of δ¹⁵N, NR; ratios range of δ¹³C, CR; total area, TA; standard ellipse area, SEAc; average distance of centroid, CD; mean nearest neighbor distance, MNND; standard deviation of nearest neighbor distance, SDNND). The results showed significant differences of δ¹³C values among all the seasons except between summer and autumn. There were significant differences of δ¹⁵N values between spring and other three seasons but no significant difference among summer, autumn, and winter. According to the results of the seven quantitative metrics, trophic structure of common fish community remarkably varied among the four seasons, as TA, SEAc, CR, NR, CD and MNND increased in succession from summer, autumn, winter to spring. Our results indicated that seasonal differences in trophic structure of common fish community were related to the fish spawning migration and the diversity of food source.

Reviews

Control of invasive Spartina alterniflora: A review

XIE Bao-hua, HAN Guang-xuan

2018, 29(10):  3464-3476.  doi:10.13287/j.1001-9332.201810.006

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Spartina alterniflora has important ecological functions in its original place, such as bank protection and land reclamation, but often has negative impacts on the local ecosystem after it is introduced into new areas. This species is often considered as an invasive one. The invasion and control of S. alterniflora have caused a great concern. We reviewed the latest research progresses in the prevention and control of S. alterniflora from six different perspectives, including physical control, chemical control, biological control, biological substitution control, integrated control, and control strategies. The theoretical basis, technical details, control effect and environmental impact of the six kinds of control technologies were analyzed. We pointed out the shortcomings of existing control technologies and proposed some suggestions such as targeted control of different ecological risk zones.

Research progress on the responses of soil respiration components to climatic warming

MA Zhi-liang, ZHAO Wen-qiang, LIU Mei, ZHU Pan, LIU Qing

2018, 29(10):  3477-3486.  doi:10.13287/j.1001-9332.201810.007

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Global carbon cycle is being profoundly altered by climate change. As an important component of the global carbon cycle, soil respiration is tightly linked to the carbon transfer among plants-soil-microbes. Soil respiration can be divided into the heterotrophic respiration and root-derived respiration (i.e., actual root respiration and rhizomicrobial respiration). Responses of soil respiration to climate warming may be different, since its components differ in occurrence sites and sources of soil organic carbon. However, the current literatures can not fully clarify the precise partition and quantification of soil respiration components. The influences of climate warming on soil respiration and related mechanisms are still unclear, which greatly limits our understanding of the accurate assessments of soil carbon cycle as well as the changes in the carbon balance of terrestrial ecosystems under climate change. We systematically summarized the progress of partitioning techniques of soil respiration components, and compared the results of partitioning of soil respiration components using different techniques. We further discussed the progress on the responses of soil respiration components to climate warming. To exactly distinguish and quantify soil respiration components, we proposed that the present techniques should be modified. Furthermore, future studies should focus on how to accurately partitioning root-derived respiration in the field for comprehensively understand soil carbon cycle and the changes of carbon budget in terrestrial ecosystems under global change. Moreover, more attention should be paid on the responses of soil respiration components to various environmental factors.

Land use and land cover change in agro-pastoral ecotone in Northern China: A review

LI Xu-liang, YANG Li-xiao, TIAN Wei, XU Xue-feng, HE Chan-sheng

2018, 29(10):  3487-3495.  doi:10.13287/j.1001-9332.201810.020

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Land use/cover change (LUCC) is the most direct manifestation of the interaction between human activities and natural ecosystems. In recent years, due to the increasing human activities, regional environment has been dramatically changed. As one of heavily influenced and fragile and vulnerable ecosystems, the agro-pastoral ecotone in Northern China is a “hot spot” for land use/cover change research. Based on a literature review of LUCC in the agro-pastoral ecotone in Northern China, we first systematically summarized the progress of the boundary definitions of the agro-pastoral ecotone, and then synthesized the current findings, methods, procedures, topics, environmental impacts and adaption of LUCC in the region. Finally, we proposed that few comprehensive, process-based ecosystem simulations and eco-environmental impact studies had been reported in the current LUCC research and called for more multi-disciplinary, multi-methods, and multi-scale researches in the future LULC research in this area.

Foraging behavior and pollination of carpenter bees Xylocopa spp. (Hymenoptera: Apidae)

HE Chun-ling, ZHU Chao-dong, WU Yan-ru

2018, 29(10):  3496-3502.  doi:10.13287/j.1001-9332.201810.038

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Large carpenter bees (the genus Xylocopa), as an important group of bees (Apidae), are common visitors to flowering plants in tropics and subtropics. Their foraging behavior is characterized by long season of activity, high diversity of foraging plants, tolerance of high temperatures, activity under low illumination levels, and buzz pollination. These traits make them to be attractive pollinators for agricultural pollination in hot climates, especially in greenhouses, night-blooming plants, and some Solanum. In recent years, large carpenter bees have been demonstrated have efficient pollination service in blueberries, passion flower, runner bean, greenhouse tomatoes and greenhouse melons in foreign countries. However, evidence for their importance and effectiveness as crop pollinators is lacking for most plant species in China. This article reviewed the research progress on foraging behavior and pollination of Xylocopa, with the aim to provide a theoretical basis for the conservation management and utilization of large carpenter bees.