Table of Content

18 September 2016, Volume 27 Issue 9

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Water use strategy of Eucalyptus urophylla ×E. grandis on karst hillslope based on isotope analysis.

DING Ya-li, CHEN Hong-song, NIE Yun-peng, WANG Sheng, ZHANG Hui-ling, WANG Ke-lin

2016, 27(9):  2729-2736.  doi:10.13287/j.1001-9332.201609.029

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Using stable isotope techniques, water sources and water use efficiencies of Eucalyptus urophylla ×E. grandis (exotic tree species) and Liquidambar formosana (native tree species, as a reference) were studied in a typical karst artificial forest, and the risk of drought stress of the plantation was discussed. The results showed that the isotope value of shallow soil water (0-50 cm) had obvious gradient features and was similar to the recent rain, while that of deep water was more stable and different from the shallow soil water. The soil water content in wet season (May and September) was higher than in dry season (October), and was higher in upslope than in downslope segment. The main water source of L. formosana was shallow soil water, which corresponded to high water use efficiency in different seasons. The main water sources for E. urophylla ×E. grandis on the upper slope and downslope segments were both shallow soil water in wet season, however, the sum of average water using the proportion of deep soil water increased for the downslope segment in the end of wet season. In dry season, E. urophylla ×E. grandis on the downslope segment mainly used shallow soil water, while it used deeper soil water on the upslope segment when soil water was relatively low. Meanwhile, the water use efficiency of E. urophylla ×E. grandis was lower compared with L. formosana, which revealed E. urophylla ×E. grandis did not get enough water supply under drought stress. The above results indicated that E. urophylla ×E. grandis would encounter high risk of water stress if extreme drought events happened in karst regions in the coming future.

Variation of satellite-based spring vegetation phenology and the relationship with climate in the Northern Hemisphere over 1982 to 2009.

CONG Nan, SHEN Miao-gen

2016, 27(9):  2737-2746.  doi:10.13287/j.1001-9332.201609.028

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In-depth understanding the variation of vegetation spring phenology is important and nece-ssary for estimation and prediction of ecosystem response to climate change. Satellite-based estimation is one of the important methods for detecting the vegetation spring phenology in Northern Hemisphere. However, there are still many uncertainties among different remote sensing models. In this study, we employed NDVI satellite product from 1982 to 2009 to estimate vegetation green-up onset dates in spring across Northern Hemisphere, and further analyzed the phenology spatio-temporal variation and the relationship with climate. Results showed that spatial mean spring phenology significantly advanced by (4.0±0.8) days during this period in the Northern Hemisphere, while spring phenology advanced much faster in Eurasia (0.22±0.04 d·a^-1) than in North America (0.03±0.02 d·a^-1). Moreover, phenology of different vegetation types changed inconstantly during the period. All five methods consistently indicated that grassland significantly advanced, while forests didn’t advance robustly among methods. In addition, the interannual change of spring phenology was mainly driven by spring temperature. The spring phenology advanced (3.2±0.5) days with 1 ℃ increase in temperature. On the contrary, we did not find significant relationship between vegetation spring phenology and spring accumulative precipitation across the Northern Hemisphere (P>0.05) in this study.

Distribution characteristics of soil organic carbon of burned area under different restorations.

LI Hong-yun, XIN Ying, ZHAO Yu-sen

2016, 27(9):  2747-2753.  doi:10.13287/j.1001-9332.201609.036

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The distribution characteristics of soil organic carbon (SOC), soil dissolved organic carbon (DOC) and soil microbial biomass carbon (MBC) under different restorations were studied in Larix gmelinii plantation, Pinus sylvestris var. mongolica plantation, artificial promotion poplar-birch forest and the natural secondary poplar-birch forest restored from burned area after the severe fire of Greater Xing’ an Mountains in 1987. The results showed that the variations in SOC, DOC and MBC ranged from 9.63 to 79.72 g·kg^-1, from 33.21 to 186.30 mg·kg^-1 and from 200.85 to 1755.63 mg·kg^-1, respectively, which decreased with soil depth increasing. There was significant diffe-rence in SOC, DOC and MBC among different restorations, with the maximum carbon contents for artificial promotion poplar-birch forest, followed by L. gmelinii plantation, natural secondary poplar-birch forest and P. sylvestris var. mongolica plantation successively. The soil microbial quotient va-ried from 1.1% under P. sylvestris var. mongolica plantation to 2.3% under artificial promotion poplar-birch forest, and its vertical distributions were different in the four restoration forests. Correlation analysis indicated that MBC had a significant positive correlation with SOC and DOC, respectively. The activity of soil organic carbon in artificial promotion poplar-birch forest was higher than in other forest stands, suggesting a stronger capacity of the soil carbon cycle through natural regeneration with artificial promotion on burned area in Greater Xing’an Mountains.

Characteristics of soil erosion on Karst slopes under artificial rainfall experiment conditions.

GAN Yi-xian, DAI Quan-hou, FU Wen-bing, YAN You-jin, PENG Xu-dong

2016, 27(9):  2754-2760.  doi:10.13287/j.1001-9332.201609.025

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Studying soil erosion process and mechanism on Karst slopes has important practical and guiding significance for controlling soil and water loss and preventing rocky desertification in Karst region. The soil erosion process and characteristics on Karst slopes were explored by artificial simulation rainfall experiment. Results showed that the soil and water loss largely came from underground hole (crack) when rainfall intensity was in the range of 30 and 50 mm·h^-1, while soil erosion occurred primarily in soil surface when rainfall intensity was 80 mm·h^-1. Surface runoff modulus and transport rate both increased with increasing slope, and decreased with increasing underground hole (crack) degree. The underground runoff modulus varied from 0.37 to 0.52, and the underground transport rate changed from 0.81 to 1.93 g·min^-1. They both decreased with increasing slope while increased firstly and then decreased with increasing rainfall intensity.

Effects of water-soluble organic matter and residue of litter on nitrogen transformation in subtropical forest soil.

MA Fen, PEI Guang-ting, MA Hong-liang, GAO Ren, YIN Yun-feng, YANG Liu-ming

2016, 27(9):  2761-2770.  doi:10.13287/j.1001-9332.201609.006

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An incubation experiment was carried out with the addition of litter filtrate, litter residue and alanine at 25 ℃ for 36 days under 60% and 90%WHC (water holding capacity) conditions. The results showed that alanine was rapidly mineralized in soil, and soil NH₄⁺-N content significantly increased by 5.4%-44.7% and 16.1%-41.3%, respectively under 60% and 90%WHC conditions compared with the control. The soil net nitrogen mineralization and ammonification rates in the two treatments were also higher than those in the control at the early stage of incubation. However, the soil NH₄⁺-N content was reduced by the addition of filtrate and residue, and the reduction degree of residue was greater. During the incubation, soil NO₃^--N content showed a linear increasing trend with the incubation time, and it was significantly higher under the 60%WHC condition than that under 90%WHC condition at the end of incubation. The mineralization of soil organic matter was limited by higher soil moisture. Therefore, the soil soluble organic carbon (SOC) content under 90%WHC condition was obviously lower than that under 60%WHC, but nitrous oxide (N₂O) emission was 1.5-63.0 times higher than that under 60%WHC. Furthermore, N₂O emission was induced significantly by the addition of litter residue under 60%WHC condition. These results indicated that there were different effects of soluble matter and litter residue on soil nitrogen transformation, and these differences would change dynamically in the decomposition process.

Collaborative application of BEPS at different time steps.

LU Wei, FAN Wen-yi, TIAN Tian

2016, 27(9):  2771-2778.  doi:10.13287/j.1001-9332.201609.017

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BEPSHourly is committed to simulate the ecological and physiological process of vegetation at hourly time steps, and is often applied to analyze the diurnal change of gross primary productivity (GPP), net primary productivity (NPP) at site scale because of its more complex model structure and time-consuming solving process. However, daily photosynthetic rate calculation in BEPSDaily model is simpler and less time-consuming, not involving many iterative processes. It is suitable for simulating the regional primary productivity and analyzing the spatial distribution of regional carbon sources and sinks. According to the characteristics and applicability of BEPSDaily and BEPSHourly models, this paper proposed a method of collaborative application of BEPS at daily and hourly time steps. Firstly, BEPSHourly was used to optimize the main photosynthetic parameters: the maximum rate of carboxylation (V_{c max}) and the maximum rate of photosynthetic electron transport (J_max) at site scale, and then the two optimized parameters were introduced into BEPSDaily model to estimate regional NPP at regional scale. The results showed that optimization of the main photosynthesis parameters based on the flux data could improve the simulate ability of the model. The primary productivity of different forest types in descending order was deciduous broad-leaved forest, mixed forest, coniferous forest in 2011. The collaborative application of carbon cycle models at different steps proposed in this study could effectively optimize the main photosynthesis parameters V_{c max} and J_max, simulate the monthly averaged diurnal GPP, NPP, calculate the regional NPP, and analyze the spatial distribution of regional carbon sources and sinks.

Effects of coordinate rotations on eddy fluxes over a forest on a mountainous terrain in Northeast China.

WANG Xing-chang, WANG Chuan-kuan

2016, 27(9):  2779-2788.  doi:10.13287/j.1001-9332.201609.012

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Coordinate rotation is an essential step in eddy covariance (EC) flux measurements particularly on complex terrains. Systematically assessing impacts of coordinate rotation methods can improve the accuracy in EC flux estimations. Taking the Maoershan flux tower in a temperate deci-duous forest on valley slopes as a case, we comprehensively examined the effects of various tilt-correction methods on sensible heat flux (H), latent heat flux (LE), CO₂ fluxes (F_c), energy ba-lance, friction velocity (u_*), and vertical velocity (w) using the standardized major axis method. Compared with the unrotated fluxes, the double rotation (DR), planar fit (PF), vertical velocity unbiased planar fit (NBPF), monthly planar fit (MPF), triple rotation (TR) and monthly sector-wist planar fit (MSWPF) changed the H by +1.5%, +3.8%, +3.1%, +3.3%, -1.3% and -7.1%, respectively. The NBPF and DR increased LE by 1.0% and 0.4%, respectively. The PF also increased LE by 0.671 W·m^-2, and the MPF decreased LE by 0.4%, but increased the intercept by 0.747 W·m^-2. In contrast, the MSWPF and TR decreased the LE by 4.5% and 15.1%, respectively. The coordinate rotation reduced the F_c by 6.0% (DR)-12.1% (TR). Among the studied methods, the PF increased the energy balance closure by about 2%, whereas the TR decreased it by about 6%. In the light of u_* and w, the TR and NBPF were inappropriate for anemometer tilt correction. Considering the precision and practical application of EC measurements, we recommend the PF as the first choice for the Maoershan flux tower site, followed by the DR. These findings are useful for tilt correction of anemometer in EC flux observations over complex terrains.

Spatial heterogeneity of canopy photosynthesis for Larix olgensis.

LIU Qiang, DONG Li-hu, LI Feng-ri, LI Xiang

2016, 27(9):  2789-2796.  doi:10.13287/j.1001-9332.201609.008

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Based on a 14-year-old planted Larix olgensis in the Maoershan Forest Farm, Heilongjiang Province in 2014, the spatial heterogeneity of photosynthetic indicators, environmental factors and photosynthetic physiological parameters were analyzed, meanwhile the relationship between net photosynthetic rate (P_n) and other indicators were studied. Results showed that in the vertical direction, P_n, stomatal conductance (g_s) and transpiration rate (T_r) were higher in upper than middle and lower canopy significantly, intercellular CO₂ concentration (C_i) increased in the sequence of upper < middle < lower canopy. Photosynthetic active radiation (PAR) decreased from outside of upper to inside of lower canopy significantly, vapor pressure deficit (VPD) and needle leaf temperature (T_l) in upper canopy were respectively higher than in middle and lower canopy significantly, while relative humidity (RH) showed no significant difference with spatial location. The mean value of maximum P_n(P_{n max}), dark respiration rate (R_d), light compensation point (LCP) and light sa-turation point (LSP) followed the pattern of upper > middle > lower canopy and decreased by 32.7%, 55.8%, 80.2% and 51.6% from upper to lower canopy respectively. Apparent quantum yield (AQY) in lower canopy was 1.2 and 1.3 times as much as that of middle and upper canopy, respectively. In the horizontal direction, P_n, g_s, T_r, PAR and VPD were significantly higher from outside to inside in the upper crown, but C_i and RH showed no significant diffe-rence. The mean value of P_{n max}, R_d, LCP and LSP declined by 0.4%, 37.7%, 42.0% and 16.4% from outside to inside, on the contrary, AQY was 0.7% higher from inside to outside. C_i was the main physiological impact factor for P_n, and PAR was an important environmental factor that had the most obvious influence on P_n, especially in weak light region. Therefore, spatial heterogeneity should be considered necessarily when simulating and/or predicting the tree canopy photosynthesis.

Spatiotemporal variation of vegetation phenology in the Daxing’an Mountains stratified by eco-geographical regions.

FU Yuan-yuan, ZHAO Jian-jun, ZHANG Hong-yan, HE Hong-shi, GUO Xiao-yi

2016, 27(9):  2797-2806.  doi:10.13287/j.1001-9332.201609.003

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Vegetation phenology is a good indicator of climate change, because of the close correlation between vegetation and climate. The Daxing’an Mountains, located in Chinese northernmost region, are more sensitive to climate change. Researching the spatio-temporal variation of vegetation phenology in this region is of great significance for assessing the influence of global change on terrestrial ecosystem. According to the eco-geographical zoning of China, the Daxing’an Mountains can be divided into for four eco-geographical regions. In this study, the spatial distribution and dynamics of vegetation phenology in the Daxing’an Mountains were analyzed using 8-km resolution GIMMS NDVI 3g dataset from 1982 to 2012. Results showed that the start of growing season in all partitions exhibited an advancing trend, and the end of growing season in all partitions had an extending trend. Vegetation phenology which was sensitive to the change of meteorological factors had a stronger correlation with temperature than with precipitation for all four eco-geographical regions. There was a significant negative correlation between the start of growing season in the northern region and spring temperature. Except for the south of the Daxing’an Mountains, the ending days of growing season in the other three eco-geographical regions had significant negative correlations with summer precipitation. The change of vegetation phenology in the whole study was obvious along with altitude and latitude.

Effects of precipitation exclusion on fine-root biomass and functional traits of Cunninghamia lanceolata seedlings.

ZHONG Bo-yuan, XIONG De-cheng, SHI Shun-zeng, FENG Jian-xin, XU Chen-sen, DENG Fei, CHEN Yun-yu, CHEN Guang-shui

2016, 27(9):  2807-2814.  doi:10.13287/j.1001-9332.201609.023

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A precipitation exclusion experiment was set up in Cunninghamia lanceolata seedling plots in Chenda State-Owned Forest Farm, Sanming, Fujian Province, which included 50% precipi-tation reduction and ambient precipitation (control). Using soil coring and in-growth core me-thods, changes in fine-root functional traits of C. lanceolata seedlings, including fine-root biomass, morphology, stoichiometry, specific root respiration, and nonstructural carbohydrates, were exa-mined after 1 year’s precipitation exclusion. The results showed that precipitation exclusion significantly decreased biomass of 0-1 mm diameter roots but had no effect on 1-2 mm diameter roots. However, adaptive morphological changes occurred in the precipitation exclusion treatment. The specific root length (SRL) of the 0-1 and 1-2 mm diameter roots increased by 21.1% and 30.5%, respectively, and root tissue density (RTD) significantly decreased and specific root surface area (SRA) significantly increased in the 0-1 mm diameter roots. Precipitation exclusion led to increase in nitrogen concentration in fine roots, but the absorption capacity for phosphorus was impeded, resulting in increased root N:P, which implied a nutritional imbalance in fine roots. Precipitation exclusion did not significantly change fine root specific respiration rate and nonstructural carbohydrate (NSC) content. However, the soluble sugar content and the ratio of soluble sugar to starch were significantly decreased, and the starch content was increased by 33.3% in the 1-2 mm diameter roots, indicating an adaptation response of C. lanceolata seedlings to reduced precipitation by increasing the storage of nonstructural carbohydrate in fine roots.

Adaptability of Camellia sasanqua leaf morphology during natural changes in temperature.

LI Lu-lu, JIANG Xin-qiang, LIU Qing-chao, LIU Qing-hua, SUN Ying-kun, WANG Kui-ling

2016, 27(9):  2815-2822.  doi:10.13287/j.1001-9332.201609.032

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In this study, the adaptability of leaf shape, structure and stomata characteristics of Camellia sasanqua to temperature variation in natural process was investigated by field morphological observation, conventional paraffin section and scanning electron microscopy methods. The results showed that, as the temperature decreased, the leaf color changed from green to dark green, toge-ther with white and purple spots on the leaves. The relative conductivity and the percentage of wi-thered leaves increased initially and then decreased during this period. The highest percentages of relative conductivity and withered leaves in March 2015 were 56.0% and 25.4%, respectively. Different leaf tissue structure indexes, including middle vein thickness, leaf thickness, upper and lower epidermis thickness, upper and lower cuticle thickness, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue to spongy tissue, cell tense ratio and vein protuberant degree were also determined during the natural temperature change from September 2014 to April 2015. Gradually, these parameters increased initially and then decreased with the decrease of temperature except spongy ratio, which showed the opposite trend. These indicators above changed significantly in different months. Stomata length and width were not significantly changed in October 2014, December 2014 and March 2015, while the percentage of completely closed stomata was higher in March 2015, compared with other months. Taken together, we proposed that the improved adaptability of cold tolerance of C. sasanqua relies on the changes of leaf structure and stomatal closure.

Field decomposition and dissolved organic matter release dynamics in leaf litter of typical trees in South China.

CAI Dan, YANG Xiu-hong, LEI Qiu-shuang, FANG Zhi-wen, WANG Shi-zhong, QIU Rong-liang, YANG Yan-hua

2016, 27(9):  2823-2830.  doi:10.13287/j.1001-9332.201609.037

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Leaf litters of Pinus elliottii (needle-leaved) and Schima superba (broad-leaved), which are commonly found in subtropical regions of South China, were decomposed in a field for 0, 30, 60, 90, 150, 210, 240 and 365 d to evaluate changes in concentrations, compositions and properties, and amount of dissolved organic matter (DOM) released and dissolved organic carbon (DOC) in soil. Although the concentrations of DOM derived from S. superba were higher than those from P. elliottii, similar variation patterns of DOM characteristics (e.g., concentrations, composition and properties) were observed between the two types of litter during decomposition. The concentrations of DOM showed a downward trend. Upward trends were obtained for the aromatization and molecular mass of DOM, as well as fulvic acid and humic acid levels in DOM, while a downward trend was found for levels of simple aromatic proteins, such as tyrosine, in DOM. During the initial phase of decomposition, DOM was generally composed of hydrophilic neutral and acidic components, which were easily decomposed and transferred, and their effects on surface soil DOC were not significant. At later stages, DOM was mainly composed of humic and fulvic acid and other aromatic, complex structure substances, which could easily adsorb on soil, and decreased the DOC concentration of surface soil.

Spatial equity analysis of urban green space from the perspective of balance between supply and demand: A case study of Futian District, Shenzhen, China.

WU Jian-sheng, SI Meng-lin, LI Wei-feng

2016, 27(9):  2831-2838.  doi:10.13287/j.1001-9332.201609.011

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Urban green space is an important ecological landscape, whose spatial distribution plays a significant role in improving the eco-environment and people’s living quality. This study was initia-ted from the perspective of supply and demand balance to evaluate the equity of distribution of urban parks, drawing on previous research, and introduced an integrated framework for evaluating the equity of urban public facilities using spatial multi-analysis. A method concerning gravity model to assess the equity of urban green space was introduced, taking the effect of boundary into account. The case study area was the Futian District of Shenzhen and its 2000 m buffer area. Then, some optimizations were suggested for better allocation of the green space. The results showed that the equity of Futian District was low. The equity of community parks was lowest, followed by that of regional parks, while the countryside ecological parks owned the highest equity. About 50% of the Futian district area was in a state of balance between supply and demand and the rest were in a state of insufficient supply. Greening rate and space allocation of parks and road traffic systems should be improved to better plan the green space in Futian District. For urban green space planning, the parks of small area should be paid more attention to meet the needs of residents for daily recreation. By taking the effect of boundary into account, we observed that the residential area on the edge of the study area could enjoy the park green space, and the green space in the boundary area outside the region would be also shared by residents on both sides of the administrative boundary.

Influences of meteorological factors on larch caterpillar population.

YU Yue, FANG Lei, FANG Guo-fei, WANG Feng-xia, YANG Jian

2016, 27(9):  2839-2847.  doi:10.13287/j.1001-9332.201609.009

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To explore the relationship between larch caterpillar population and meteorological factors, a suite of linear regression models were developed. We used a stepwise regression approach to obtain the best model based on the Akaike information criterion (AIC). We also identified the key meteorological factors based on relative weight, and analyzed their marginal influences on larch ca-terpillar population. Our modeling results showed that meteorological conditions during the young larva stage and breeding stage played a key role in impacting larch caterpillar population. In contrast, meteorological conditions during the middle larva stage and old larva stage had a weaker effect. The mean daily relative humidity during young larva stage, the accumulated daily temperature less than -22 ℃ during young larva’s overwintering stage, and the total rainfall in breeding stage were the key meteorological factors affecting the population of larch caterpillar. With the increase of one standard deviation from the mean daily relative humidity during young larva stage and the total rainfall in breeding stage, the larch caterpillar population would be reduced by 62% and 35% of standard deviation, respectively. In contrast, one standard deviation increase of the accumulated daily temperature less than -22 ℃ during young larva’s overwintering stage would increase larch caterpillar population by 40% of standard deviation. Our study suggests that the larch caterpillar population in the future may explode in response to global warming, and its infestation could exhibit a new pattern. It is therefore very important to establish a long-term population monitoring system.

Effects of labile carbon addition on organic carbon mineralization and microbial growth strategies in subtropical forest soils.

LIAO Chang, TIAN Qiu-xiang, WANG Dong-ya, QU Lai-ye, WU Yu, LIU Feng

2016, 27(9):  2848-2854.  doi:10.13287/j.1001-9332.201609.038

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Deep soil is a major organic carbon pool in terrestrial ecosystems. Labile carbon inputs can stimulate soil organic carbon (SOC) mineralization, causing priming effect, which in turn affects soil carbon emission. However, the mechanism of the priming effect in deep soil is still unclear. Therefore, to know how deep soil responds to labile carbon addition is essential for better understanding of deep soil carbon dynamics. In this study, we incubated three profiled soils (0-10 cm, 10-30 cm, 30-60 cm) from a subtropical forest with ¹³C-labeled glucose addition to analyze the priming effects and their relationship with the shift of microbial communities (r-K strategies). The results showed that glucose addition increased SOC mineralization in all soil layers, causing positive priming effects. But glucose addition significantly decreased the specific growth rates of microorgani-sms for all soils, indicating a relative decrease of r-strategists and a relative increase of K-strategists in the microbial community. Thus, we inferred that the positive priming effect was possibly attributed to the increased contribution of K-strategists. The priming effect in deep soil (156%) was significantly higher than that in surface soil (45%). Meanwhile, the ratio of dissolved organic carbon (DOC) and dissolved nitrogen (DN) after glucose addition was significantly higher in deep soil (76.03) than that in surface soil (13.00). These results suggested that there existed a stronger nitrogen limitation in deep soil. The microorganisms in deep soil tended to decompose recalcitrant SOC to acquire nitrogen, which then caused a greater priming effect. Overall, deep soil was more vulne-rable to labile carbon addition due to its carbon and nitrogen limitations, and hence was likely more sensitive to climate change in the future.

Responses of soil microbial community structure and function to simulated warming in alpine forest.

YANG Lin, CHEN Ya-mei, HE Run-lian, DENG Chang-chun, LIU Jun-wei, LIU Yang

2016, 27(9):  2855-2863.  doi:10.13287/j.1001-9332.201609.026

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Soil samples were collected from an alpine coniferous forest. Soil cores with soil organic layer above and mineral soil layer below were incubated in plant growth chambers during 10 weeks. Taking the annual average soil temperature in the alpine forest as the control, and other two levels of temperature were increased 2 and 4 ℃, respectively, to investigate the responses of soil microbial community and soil enzyme activity to warming. The results showed that warming significantly reduced PLFAs content of bacteria in soil organic layer and PLFAs content of G^- in the mineral soil layer, whereas soil fungi was slightly influenced by warming. Warming caused the G⁺/G^- increasing and changed the microbial community structure, but had no significant effect on soil enzymes activity, i.e., laccase (Lac), β-1,4-glucoside (BG), acid phosphate (AP), β-1,4-N-acetylglucosaminidase (NAG). There were significantly positive correlations between fungi, bacteria, G⁺ and G^-, showing the coordinated growth trend between soil microbial communities. There was significantly negative correlation between BG and bacteria, showing the BG competing for carbon source utilization with soil microbial community. In consequence, the soil microbe types responded differently to warming. Bacteria were more sensitive to temperature than fungi, and fungi had stronger ability to tolerate warming in the alpine forest.

Effects of grazing on the composition of soil animals and their decomposition function to Stipa grandis litter in Inner Mongolia typical steppe, China.

YANG Zhi-min, Hasitamier, LIU Xin-min

2016, 27(9):  2864-2874.  doi:10.13287/j.1001-9332.201609.033

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Grazing has been considered to be an important factor determining the composition of soil animals and decomposition of leaf litter in grassland ecosystem. Sampling plots were selected in ungrazed grassland, grazed grassland and sandy land. Litter bags were used to compare the changes of physicochemical properties of Stipa grandis litter and the composition of soil fauna in the process of the litter decomposition in Baiyinxile, Inner Mongolia, since 2010 to 2012. A total number of 67056 soil animals were captured, belonging to five phyla and eight classes, including 23 families of mites and 19 families of insects. After 780 days’ decomposition, the loss of the organic matter of S. grandis litter was from 92.5% to 40.0% in the ungrazed grassland, and to 41.3% in the grazed grassland, with no significant difference observed. However, there was a significant difference (P<0.05) between the ratio of litter residues of the ungrazed grassland (50.0%) and that of the grazed grassland (23.0%). The abundance of soil animals in the residual litters was significantly decreased in the grazed grassland compared to the ungrazed grassland. When the litter was moved into the sandy land, the decomposition rate of organic matter in the residual litter was not significant changed but the ratio of litter residue declined significantly, and the composition of mite community in the resi-dual litter changed significantly. Our results illustrated that grazing activity could affect the composition and abundance of soil fauna in temperate grassland, but slightly influenced the decomposition of organic matter. Therefore, soil animals had relatively weak direct effects on the decomposition of litter in this semi-arid region.

Estimations of application dosage and greenhouse gas emission of chemical pesticides in staple crops in China.

ZHANG Guo, LU Fei, HUANG Zhi-gang, CHEN Shun, WANG Xiao-ke

2016, 27(9):  2875-2883.  doi:10.13287/j.1001-9332.201609.031

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Chemical pesticides play an important role in improving crop yield in modern agriculture. However, commonly overuse of pesticide in China leads to serious environmental problems and food safety hazards. Based on a national questionnaire survey of farmers across China in 2012, the situation of pesticide applications to rice, wheat, and corn in 2011, and their corresponding greenhouse gas (GHG) emissions were investigated. The survey showed that at least 54 types of insecticide, 24 types of fungicide, and 50 types of herbicide were in use across three crops. 32% of rice farmers applied biological pesticides in China. The amounts of pesticides applied to the three cereal crops were 30.8, 16.5, and 58.3 kt for insecticides, fungicides, and herbicides, respectively. The total GHG emission from these pesticides was 1.5 Tg Ce, and the GHG emissions from these insecticides, fungicides, and herbicides accounted for 23.8%, 16.9%, and 59.3% of the total emission, respectively. In south China, the amounts of pesticides applied occupied 51% of the national total. For the production of each kilogram of grain, the amounts of pesticides applied were 0.22, 0.18, and 0.24 g for rice, wheat, and corn, respectively. Therefore, the sums of pesticides applied by crop types were 44.4 kt for rice, 21.4 kt for wheat, and 39.7 kt for corn. Meanwhile, the GHG emissions of pesticides were 665.5, 250.1, and 547.5 Gg Ce for rice, wheat, and corn, respectively. For pesticide types, organophosphorus insecticides accounted for 69% of total insecticide use in China, while benzimidazole, organophosphorus, azole, and organic sulfur fungicides together contributed 87% of total fungicide use. In addition, the use of anilide, organic heterocyclic, and organophosphorus herbicides contributed 85% of the total herbicide application. Therefore, the reduction of pesticide use would play an important role in food safety and environmental safety, and GHG mitigation in agricultural sector in China.

Spatial distribution and potential ecological risk assessment of heavy metals in sediments of Yalu River estuary wetland mudflat.

ZHANG Chun-peng, LI Fu-xiang

2016, 27(9):  2884-2890.  doi:10.13287/j.1001-9332.201609.005

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Kriging interpolation analysis was conducted with ArcGIS to find out the distribution characteristics of heavy metals concentrations in the surface sediments of the coastal wetland mudflat on the Yalu River estuary, environmental risk index and Hakanson potential ecological risk index were used to assess their extents of pollution in this area.The concentrations of heavy metals in the surface sediments of the study area were at a relatively high level compared with the typical estuarine wetland. The concentration of heavy metals in the east was higher than that in the west, and in the human activity area, the concentration was higher. Cu was found to contribute the most to the pollution status based on environmental risk index method, while Hg and Cd produced the greatest potential ecological harm according to Hankanson Potential ecological risk index method. The average potential ecological risk index (RI) of the Yalu River estuary wetland was 189.30 (ranged from 93.65-507.20), suggesting a moderate ecological risk. However, the potential ecological risk was highest in the east and should be treated as the major heavy metal pollution prevention area in the future.

Non-point source pollution simulation under land use change scenarios in Hun-Taizi River watershed.

LI Zhu-heng, LIU Miao, LI Chun-lin, SUN Ju, SUI Jin-ling, WU Yi-lin

2016, 27(9):  2891-2898.  doi:10.13287/j.1001-9332.201609.004

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Non-point source (NPS) pollution has become a major source of water pollution in recent years. The research of NPS pollution mechanism and control has an important scientific and practical meaning. To study the effect of land use change on NPS pollution load, near future land use of Hun-Taizi River watershed was simulated under three scenarios based on CLUE-S model, including urban planning, historical trend and ecological protection scenarios. NPS pollution was simulated based on SWAT model. The simulated results of SWAT were compared with measured data. The response of NPS pollution to land use change and landscape pattern was studied with the combination of the two models in three land use scenarios. The results showed that the NPS pollution simu-lation with SWAT had high accuracy, which showed the suitability of SWAT model in the study area. The NPS pollution load increased under urban planning and historical trend scenarios but decreased under ecological protection scenario. The difference in three scenarios indicated that land use and landscape pattern impacted NPS to a certain extent, which showed that scientific ecological construction could effectively reduce NPS pollution load. This study provided a new study case for NPS pollution research at watershed scale, a scientific basis for implementation of non-point source pollution control and best management practices, and a reference for related policy making.

Response of water yield function of ecosystem to land use change in Nansi Lake Basin based on CLUE-S model and InVEST model .

GUO Hong-wei, SUN Xiao-yin, LIAN li-shu, ZHANG Da-zhi, XU Yan

2016, 27(9):  2899-2906.  doi:10.13287/j.1001-9332.201609.039

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Land use change has an important role in hydrological processes and utilization of water resources, and is the main driving force of water yield function of ecosystem. This paper analyzed the change of land use from 1990 to 2013 in Nansi Lake Basin, Shandong Province. The future land use in 2030 was also predicted and simulated by CLUE-S model. Based on land use scenarios, we analyzed the influence of land use change on ecosystem function of water yield in nearly 25 years through InVEST water yield model and spatial mapping. The results showed that the area of construction land increased by 3.5% in 2013 because of burgeoning urbanization process, but farmland area decreased by 2.4% which was conversed to construction land mostly. The simulated result of InVEST model suggested that water yield level of whole basin decreased firstly and increased subsequently during last 25 years and peaked at 232.1 mm in 2013. The construction land area would increase by 6.7% in 2030 based on the land use scenarios of fast urbanization, which would lead to a remarkable growth for water yield and risk of flowing flooding. However, the water yield level of whole basin would decrease by 1.2 % in 2013 if 300 meter-wide forest buffer strips around Nansi Lake were built up.

Comprehensive evaluation of ecosystem quality in the Shule River basin, Northwest China from 2001 to 2010.

PAN Jing-hu, DONG Lei-lei

2016, 27(9):  2907-2915.  doi:10.13287/j.1001-9332.201609.015

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Shule River Basin is a typical arid inland river basin and ecoenvironment-fragile region. Comprehensive evaluation of ecosystem quality in the Shule River basin is of great significance. The ecosystem productivity index (EPI), the ecosystem stability index (ESI) and the ecosystem bea-ring capacity index (EBCI) were proposed to build a remote sensing comprehensive evaluation mo-del to evaluate the ecosystem quality of Shule River basin during 2001-2010. The results showed that the mean ecosystem quality value in the Shule River basin was 43.21, which was at a relatively low level. The values of EPI, ESI, EBCI were 47.16, 58.09 and 28.52, respectively, indicating that ecosystem carrying capacity in the Shule River basin was poor in the period from 2001 to 2010. However, EPI and EBCI rose by 18.9％ and 20.1％, respectively, but ESI decreased slightly by 9.4%. The ecosystem quality showed a trend of increasing first and then decreasing from 2001 to 2010. The average ecosystem quality values in 2001, 2005 and 2010 were 43.71, 44.80 and 41.13, respectively. The farmland ecosystem quality was better than that of the other ecosystem types, and the water area ecosystem quality was the lowest. Overall, the comprehensive evaluation value of the artificial ecosystem quality was 46.43, which was significantly higher than that of the natural ecosystems.

Accuracy evaluation of multi-satellite precipitation products over Circum-Bohai-Sea Region.

LI Rui-ze, ZHANG An-ding, ZHANG Hua, JIANG De-juan

2016, 27(9):  2916-2924.  doi:10.13287/j.1001-9332.201609.035

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Precipitation is a key variable of the global energy and water cycle. The accuracy of precipitation data is essential for monitoring and forecasting flood and drought, as well as water resources management. Based on daily precipitation data of 55 meteorological stations over Circum-Bohai-Sea region during 1998-2014, the accuracy was evaluated and compared among 3 satellite-based precipitation products, i.e., TRMM 3B42 V7, CMORPH, and PERSIANN from daily to monthly scale. Their errors were quantified for different seasons. Results showed that generally, TRMM 3B42 V7 had the best performance while PERSIANN had the largest error. However, CMORPH had the highest detection rate of rainfall events. The rainfall was slightly overestimated by 3B42 V7 but underestimated by CMORPH and PERSIANN. Seasonally, the skill score in summer was higher than that in other seasons, and the capturing capability was much lower in winter. Meanwhile, the correlation coefficient and root mean square error varied with seasons. The performance of 3 satellite-based precipitation products increased from the daily to monthly scale. Larger errors still existed in the daily rainfall estimates, and especially the rainstorm was seriously underestimated. This study provided a basis for the use of satellite precipitation products in precipitation estimation and its application in climate and hydrological simulation over Circum-Bohai-Sea region.

Efficiency of industrial energy conservation and carbon emission reduction in Liaoning Pro-vince based on data envelopment analysis (DEA)method.

WANG Li, XI Feng-ming, LI Jin-xin, LIU Li-li

2016, 27(9):  2925-2932.  doi:10.13287/j.1001-9332.201609.002

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Taking 39 industries as independent decision-making units in Liaoning Province from 2003 to 2012 and considering the benefits of energy, economy and environment, we combined direction distance function and radial DEA method to estimate and decompose the energy conservation and carbon emissions reduction efficiency of the industries. Carbon emission of each industry was calculated and defined as an undesirable output into the model of energy saving and carbon emission reduction efficiency. The results showed that energy saving and carbon emission reduction efficiency of industries had obvious heterogeneity in Liaoning Province. The whole energy conservation and carbon emissions reduction efficiency in each industry of Liaoning Province was not high, but it presented a rising trend. Improvements of pure technical efficiency and scale efficiency were the main measures to enhance energy saving and carbon emission reduction efficiency, especially scale efficiency improvement. In order to improve the energy saving and carbon emission reduction efficiency of each industry in Liaoning Province, we put forward that Liaoning Province should adjust industry structure, encourage the development of low carbon high benefit industries, improve scientific and technological level and adjust the industry scale reasonably, meanwhile, optimize energy structure, and develop renewable and clean energy.

Industrial ecological development of Jilin Province, Northeast China based on structure optimization vision.

ZHAO Dan-yang, TONG Lian-jun, GUO Fu-you, QIU Fang-dao

2016, 27(9):  2933-2940.  doi:10.13287/j.1001-9332.201609.007

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Based on the interactive coercing mechanism between the industrial system and the ecosystem, we evaluated Jilin’s ecologicalization of industrial structure, employing the systematic ana-lysis method and the comprehensive index evaluation method, and explored the spatio-temporal cha-racteristics.The result showed that the ecological level of industrial structure as well as the industrial structure optimization and resource-environmental efficiency had been significantly improved in 2000-2013. The regional difference showed a trend of resource-environmental efficiency > industrial structure optimization > ecologicalization of industrial structure. Spatially, it demonstrated a “higher in west, lower in east” pattern, and at city scale, it showed a decreasing trend from the core (Changchun) to outside. According to the coordination of industrial structure optimization and resource-environmental efficiency, we categorized the nine cities in Jilin Province into four ecologica-lization types: high coordination type, low coordination type, economic development ahead, and ecological development ahead.

Spatial and temporal evolution of the ecological environment and economy coordinated development in Hebei Province, China.

KONG Wei, REN Liang, WANG Shu-jia, LIU Yu-feng

2016, 27(9):  2941-2949.  doi:10.13287/j.1001-9332.201609.030

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Based on the constructed evaluation index system of ecological environment and economy coordinated development in Hebei Province, accompanied by introducing the Coupling Degree Mo-del, the paper estimated the ecological environment comprehensive index, the economic comprehensive index and the coupling degree of ecological environment and economy coordinated development of Hebei Province from 2000 to 2014 and 11 cities in 4 years (2000, 2006, 2010, 2014). The results showed that during the study period, the level of the coordinated development of the eco-logical environment and economy in Hebei Province had been increasing, from the brink of a recession to the well coordinated development, which had gone through 3 evident stages. The coordinating degree of ecological environment and economy of the 11 cities increased year by year, and pre-sented significant difference in spatial distribution. Through analyzing the spatial and temporal evolution mechanism of the ecological environment and economy coordinated development in Hebei Province, the policy, economy, industry and location were the key contributing factors, accordingly, suggestions on the further coordinated development of ecological environment and economy in Hebei Province were proposed.

Spatial-temporal characteristics of thermal resources and its influence on the growth of double cropping rice in the middle and lower reaches of the Yangtze River,China.

XIE Yuan-yu, HUANG Shu-e, TIAN Jun, WANG Yu, YE Qing

2016, 27(9):  2950-2958.  doi:10.13287/j.1001-9332.201609.013

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The spatial-temporal characteristics of thermal resources are the main factor controlling the spatial distribution patterns of double cropping rice. Based on daily average temperature data collected from 240 weather stations in Hunan, Jiangxi and Hubei provinces, our study analyzed the change characteristics of thermal resources during thermal growth period and safe growth period of double cropping rice in the middle and lower reaches of the Yangtze River. Furthermore, we quantified the change trends of spatial pattern for the rice cropping systems with different rice varieties and the northern limit of double cropping rice. The results indicated that the thermal resources of double cropping rice displayed a significant increasing trend during both thermal and safe growth periods, with an abrupt change in 2000 in terms of the Mann-Kendall test. The safe planting date of early rice advanced for 3-7 days and the safe heading date of late rice delayed for 2 days. Averagely, the safe growth period extended by about 7 days, and the planting northern limit of double cropping rice shifted 200 km northward, approaching to the latitude of 33° N. Meanwhile, many areas with cropping systems of ‘early maturing early rice + mid-maturing late rice’ and ‘mid-maturing early rice + mid-maturing late rice’ were replaced by ‘mid-maturing early rice + late-maturing late rice’. Our study revealed the feasibility to shift the double cropping rice system northward and replace early and mid-maturing rice variety with mid and late maturing rice variety due to the increa-sing thermal resources during growth period of double cropping rice under climate change.

Effects of maize/peanut intercropping row ratio and phosphate fertilizer on photosynthetic characteristics of maize.

JIAO Nian-yuan, LI Ya-hui, YANG Xiao, YIN Fei, MA Chao, QI Fu-guo, LIU Ling, XIONG Ying

2016, 27(9):  2959-2967.  doi:10.13287/j.1001-9332.201609.019

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To get better insight into the photosynthetic mechanism of plant adaptation to strong light in intercropped maize, a field trial was carried out in 2014-2015 to investigate the effects of maize/peanut intercropping row ratio and phosphate fertilizer on diurnal variation in light intensity of maize canopy, SPAD value, and the curves of photosynthetic response of net photosynthetic rate (P_n) to photon flux density (PFD) and to CO₂ of functional leaves. The field trial comprised 2 rows maize intercropped with 2 rows peanut (2:2, R₁), 2 rows maize intercropped with 4 rows peanut (2:4, R₂) and 2 rows maize intercropped with 8 rows peanut (2:8, R₃). Results showed that the light intensity of intercropped maize canopy was R₃>R₂>R₁. From pre-tasselling to filling stage, the SPAD value, apparent quantum efficiency (AQY), light compensation point (LCP), light saturation point (LSP), maximum net photosynthetic rate, carboxylation efficiency (CE), maximum electron transfer rate (J_max), triose phosphate utilization (TPU), stomatal conductance (g_s), transpiration rate (T_r) and P_n in ear leaves of intercropped maize were R₃>R₂>R₁, but the intercellular CO₂ concentration (C_i) was R₁>R₂>R₃. At dough stage, the AQY, LSP_n, g_s, CE, J_max and TPU in ear lea-ves of intercropped maize in R₃ intercropping system were lower than those in R₂ intercropping system. The photosynthetic indices, such as AQY, LSP_n, CE, V_{c max}, J_max and TPU were increased by phosphate fertilizer application. These results suggested that the key mechanisms that enhanced strong light utilization ability of intercropped maize were attributed to gradual improvement in g_s, AQY, CE, V_{c max}, J_max and TPU of ear leaves with increasing light intensity, however, beyond a certain light intensity, intercropped maize leaves were prone to premature senescence. Nonetheless, phosphate fertilizer could improve light utilization and delay leaf senescence in intercropped maize.

Seed vigor evaluation based on adversity resistance index of wheat seed germination under stress conditions.

CHEN Lei-tai, SUN Ai-qing, YANG Min, CHEN Lu-lu, MA Xue-li, LI Mei-ling, YIN Yan-ping

2016, 27(9):  2968-2974.  doi:10.13287/j.1001-9332.201609.014

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A total of 16 wheat cultivars were selected to detect seed vigor of different genotypes using standard germination test, seed germination test under stress conditions and field emergence test. The adversity resistance indices of seed vigor indices and field emergence percentage under different germination conditions were used as the indices to evaluate adversity resistance. Principal component analysis and cluster analysis were used for the comprehensive evaluation of seed vigor. Results showed that drought stress, artificial aging and cold soaking treatments affected seed vigor to some extent. The adversity resistance indices of the artificial aging and cold soaking tests were significantly positively correlated with the field emergence percentage, while the adversity resistance index of drought stress test had no significant correlation with the field emergence percentage. 16 wheat cultivars were classified as three groups based on the principal component analysis and cluster analysis. Yunong 949, Yumai 49-198, Luyuan 502, Zhengyumai 9987, Shimai 21, Shannong 23, and Shixin 828 belonged to high vigor seeds. Xunong 5, Yunong 982, Tangmai 8, Jimai 20, Jimai 22, Jinan 17, and Shannong 20 belonged to medium vigor seeds. The other two cultivars, Chang 4738 and Lunxuan 061, belonged to low vigor seeds.

Effects of deep plowing time during the fallow period on water storage-consumption characteristics and wheat yield in dry-land soil.

DANG Jian-you, PEI Xue-xia, ZHANG Ding-yi, WANG Jiao-ai, ZHANG Jing, WU Xue-ping

2016, 27(9):  2975-2982.  doi:10.13287/j.1001-9332.201609.001

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Through a three-year field trail, effects of deep plowing time during the fallow period on water storage of 0-200 cm soil before sowing, water consumption of growth period, and growth and development of wheat were investigated. Results demonstrated that soil water storage (SWS) of the fallow period was influenced by deep plowing time, precipitation, and rainfall distribution. With postponing the time of deep plowing in the fallow period, SWS was increased firstly, and then decreased. SWS with deep plowing in early or middle of August was 23.9-45.8 mm more than that with deep plowing in mid-July. It would benefit SWS when more precipitation occurred in the fallow period or more rainfall was distributed in August and September. Deep plowing at a proper time could facilitate SWS, N and P absorption of wheat, and the number of stems before winter and the spike number. The yield of wheat with deep plowing in early or middle August was 3.67%-18.2% higher than that with deep plowing in mid-July, and it was positively correlated with water storage of 0-200 cm soil during the fallow period and SWS of each soil layer during the wheat growth period. However, this correlation coefficient would be weakened by adequate rainfall in spring, the critical growing period for wheat. The time of deep plowing mainly affected the water consumption at soil layer of 60-140 cm during wheat growth. Under current farming conditions of south Shanxi, the increased grain yield of wheat could be achieved by combining the measures of high wheat stubble and wheat straw covering for holding soil water and deep plowing between the Beginning of Autumn (August 6th) and the Limit of Heat (August 21st) for promoting soil water penetration characteristics to improve the number of stems before winter and spike.

Responses of dry matter, nitrogen accumulation and distribution and nitrogen utilization of pepper to new-type fertilizers in Guizhou yellow soil.

ZHANG Meng, XIAO Hou-jun, ZHAO Huan, AN Jiang-yong, QIN Song, GOU Jiu-lan, HU Gang

2016, 27(9):  2983-2990.  doi:10.13287/j.1001-9332.201609.018

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In order to explore the pepper yield responses to new-type fertilizers in yellow soil in Guizhou Province, a pot experiment, with the variety of “Bola 5”, was conducted to estimate the effects of four new-type fertilizers, including water retaining fertilizer (BSX), stable slow release fertilizer (WDX), coated slow release fertilizer (BMX) and long-lasting nitrogen fertilizer (CXDF), on the accumulation and distribution of dry matter and nitrogen (N) uptake and N use efficiency. The results showed that the application of new-type fertilizers could significantly influence the accumulation and distribution of dry matter and shoot N uptake. Compared with dry matter accumulation, the start time and the end time of N accumulation during fast-growing period were advanced by 17-26 d and 28-45 d, respectively, and the duration of N accumulation in fast-growing period was shorter by 7-23 d, which indicated that the occurrence time of N accumulation was prior to the accumulation of dry matter. In contrast to the common compound fertilizer (FHF) treatment, the occurrence time of dry matter and nitrogen accumulation in the treatments with new-type fertili-zers (BSX, WDX, BMX and CXDF) were obviously lagged, and the lag time was longest in the BMX treatment. However, it had a shorter duration of fast-growing stage and a maximum accumulation rate for the WDX treatment, revealing that WDX could realize the high nutrient use efficiency in a short time. The post-anthesis dry matter and N accumulation accounted for 63.0%, 20.1% and 73.3%, 20.5% for the BSX and BMX treatments, respectively, while these proportions for the WDX were 59.3% and 11.6%, respectively. This indicated that BSX and BMX were beneficial to promote dry matter and N assimilation after flowering, while WDX was conducive to dry matter and nutrients accumulation before flowering. Compared with the FHF treatment, new-type fertilizers (BSX, WDX and BMX) application could significantly improve N use efficiency. Nitrogen partial productivity, nitrogen agronomic efficiency and nitrogen apparent utilization rate of the WDX treatment were the highest, with the average of 66.74 kg·kg^-1, 44.28 kg·kg^-1 and 54.7%, respectively. Consequently, these four new-type fertilizers were sui-table for pepper cultivation in Guizhou, in which the yield response to the WDX was the best.

Effects of polyacrylamide on soil erosion and soil nutrient loss in sloped apple orchards.

LI Jing-jing, ZOU Chao-yu, BAI Gang-shuan

2016, 27(9):  2991-2999.  doi:10.13287/j.1001-9332.201609.021

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In order to improve the soil environment, reduce soil erosion and soil nutrient loss, and explore the suitable dry broadcasting rate of polyacrylamide (PAM) in sloped apple orchard, experiments of different dry broadcasting rates of polyacrylamide were carried out in apple orchards with a slope of 20° in the hilly-gully region of northern Shaanxi from 2010 to 2012. PAM treatment levels included 0, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 g·m^-2. Surface runoff, eroded sediment, soil nutrient loss, and the growth of apple trees were monitored. Results showed that the surface runoff and runoff yield times from May to July exhibited a “V” shape with the increase of PAM application rate, and reached a minimum at the 1.0 g·m^-2 level. However, the sediment yield decreased with increasing the PAM application rate. The concentrations of the ammonium nitrogen, available phosphorus, and available potassium in surface runoff and sediment decreased with increa-sing the PAM application rate. PAM significantly reduced the content of nitrate nitrogen in surface runoff, whereas it had no significant effect on nitrate nitrogen in sediment. Organic matter, total nitrogen, total phosphorus, and total potassium in the sediment decreased with increasing the PAM application rate. Moreover, PAM improved average fruit mass and fruit yields in sloped orchards, but it had no significant effect on the growth of apple trees and apple fruit flavor. An application le-vel of PAM at 1.0 g·m^-2 should be suitable in sloped apple orchards.

Present fertilization and the potential of high yield on watermelon in Jiangsu Province, China.

ZHANG Shuang, SHI Yan-nan, WANG Shuo, DONG Ya, LIU Le-sheng, DONG Cai-xia, REN Li-xuan, XU Guo-hua

2016, 27(9):  3000-3008.  doi:10.13287/j.1001-9332.201609.027

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Watermelon fertilization in main planting regions of Jiangsu Province was investigated in order to evaluate the characteristics of efficient fertilization and improve the yield and quality of watermelon. The investigation was performed in Dongtai, Dafeng, Sihong, Pizhou and Donghai. The results showed that the average yield of watermelon in Jiangsu Province was 48325 kg·hm^-2, and the highest yield was 97500 kg·hm^-2. The watermelon yield was improved by straw return of 14-15 t·hm^-2. The watermelon yield was increased with the increase of organic manure application under the quantity of 30 t·hm^-2, while it trended to decrease when the manure application exceeded 30 t·hm^-2. The peasant households of efficient high yield and inefficient high yield on organic manure were 16.5% and 29.1%, respectively. The peasant households of efficient high yield and inefficient high yield on total nitrogen fertilizer were 14.9% and 26.3%, while those on chemical nitrogen fertilizer were 19.6% and 22.4%, respectively. The peasant households of efficient high yield and inefficient high yield on total phosphorus fertilizer were 20.9% and 21.8%, while those on chemical phosphorus fertilizer were 13.7% and 29.5%, respectively. The peasant households of efficient high yield and inefficient high yield on total potassium fertilizer were 14.9% and 26.3%, while those on chemical potassium fertilizer were 29.6% and 12.2%, respectively. Compared to basic application, basic and top application combination enhanced the watermelon yield, so did the foliar fertilization. It was suggested that the peasant households of inefficient high yield and inefficient low yield should decrease the fertilization quantity to improve fertilizer efficiency, while those of efficient low yield should regulate nutrient components and fertilization stage.

Effects of exogenous salicylic acid and brassinolide on photosynthesis of cucumber seedlings under low temperature stress.

XU Xiao-yun, YU Ji-hua, XIE Jian-ming, HU Lin-li, LI Jie

2016, 27(9):  3009-3015.  doi:10.13287/j.1001-9332.201609.020

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An experiment was conducted to investigate the mechanism of the regulation of salicylic acid (SA) and 2,4-epibrassionolide (EBR) on photosynthesis in cucumber (Cucumis sativa) seedlings under low temperature stress. Taking cucumber cultivar ‘Youbo1-5’ as material, the seedlings were pre-treated with 1 mmol·L^-1 SA or 0.1 μmol·L^-1EBR (sprayed once a day), and then were exposed to chilling temperature (10 ℃/5 ℃, PFD 80 μmol·m^-2·s^-1) after being pre-treated 2 days. The results showed that the growth and net photosynthetic rate (P_n) of cucumber seedlings were decreased under low temperature stress. However, the P_n, maximal photochemical efficiency of PSⅡ (F_v/F_m), actual photochemical efficiency of PSⅡ (Φ_PSⅡ) and photochemical quenching coefficient (q_P) were significantly improved in SA- and EBR-pretreated seedlings, and the increase range of non-photochemical quenching coefficient (NPQ) was decreased. Moreover, the activities of ribulose 1,5-biphosphate carboxylase/oxygenase (Rubisco), sedoheptulose-1,7-bisphosphatase (SBPase), fructose-1,6-bisphosphate aldolase (FBA) and transketolase (TK) were signi-ficantly increased. These findings suggested that SA and EBR improved photosynthesis of cucumber seedlings by promoting the activities of key enzymes and increased low temperature tolerance.

Effect of applying phosphorus bacteria fertilizer on bacterial diversity and phosphorus availability in reclaimed soil.

MENG Hui-sheng, HONG Jian-ping, YANG Yi, WANG Xiang-ying, LI Ting-liang, LI Li

2016, 27(9):  3016-3022.  doi:10.13287/j.1001-9332.201609.040

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A located field experiment of applying phosphorus bacteria fertilizer for five years was carried out to study the effects of applying phosphorus bacteria fertilizer on the characteristics of microbial community structure in reclaimed soil. We studied the diversity of bacterial community using 16S rDNA gene sequencing and analyzed the relationship between bacterial community and Olsen-P, alkaline phosphatase. Seven treatments including control, chemical fertilizer, manure, manure and chemical fertilizer, chemical fertilizer and phosphorus bacteria, manure and phosphorus bacteria, and, manure,chemical fertilizer and phosphorus bacteria were conducted. The results showed that the relative abundance of Actinobacteria and Proteobacteria in reclaimed soil was the largest, which was 21.6％-32.2％ and 13.8％-28.9％, respectively. Operational taxonomic units (OTU) number and Chao1 index of the treatment of manure, chemical fertilizer and phosphorus bacteria fertilizer was 809 and 26190, which was the highest. Phosphorus bacteria fertilizer could improve the relative abundance of soil Actinomycetes and Proteobacteria and decrease that of soil Acidobacteria, Thermotogae and Nitrospira, and had stimulatory effect on Nocardioides and Flexibacter. The treatment of manure, chemical fertilizer and phosphorus bacteria fertilizer could improve the Olsen-P and alkaline phosphatase activities in reclaimed soil. Correlation coefficients between Proteobacteria and Olsen-P, alkaline phosphatase were the highest (0.900 and 0.955). To a certain extent, Proteobacteria could be used as the sensitivity index of soil phosphorus availability.

Impacts of genetically modified soybean leaf residues on Folsomia candida.

ZHOU Lin, WANG Bai-feng, LIU Xin-ying, JIANG Ying, WANG Da-ming, FENG Shu-dan, SONG Xin-yuan

2016, 27(9):  3023-3028.  doi:10.13287/j.1001-9332.201609.016

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When the genetically modified soybean is planted in the field, the expression product of exogenous gene could be exposed in the soil ecosystem and bring potential risk to the soil fauna, with the form of leaves and other debris. A few of genetically modified soybeans developed by China independently were used in our study as materials. They were Phytophthora-resistant soybean harboring hrpZm gene (B4J8049), leaf-feeding insect-resistant soybean harboring Cry1C gene (A2A8001) and Leguminivora glycinivorella-resistant soybean harboring Cry1Iem gene (C802). By feeding Folsomia candida with the three genetically modified soybeans for continuous 60 days, the surviving rate, reproductive rate and changes on the body length of F. candida were studied. The results showed that all the three genetically modified soybeans of B4J8049, A2A8001 and C802 had no significant adverse effects on the growth of F. candida, as an environmental indicator organism. It was initially inferred that they were environmentally safe under short-term exposure, which provided basic data of ecological safety for their wide cultivation.

Joint effect of co-exposure of Cu and chlorpyrifos on the toxicity of earthworm.

XU Dong-mei, RAO Gui-wei

2016, 27(9):  3029-3034.  doi:10.13287/j.1001-9332.201609.024

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In order to reveal the toxicity effect and risk of co-exposure of Cu and chlorpyrifos in the current soil environment of China, using the earthworm Eisenia fetida as model organism, the effect of single, and co-exposure of Cu and chlorpyrifos on the growth and antioxidant response of earthworm were analyzed by using the methods of filter paper test and artificial soil test. The results showed that the growth rate of earthworm tended to decrease with the increase of single exposure concentrations of Cu and chlorpyrifos in artificial soil test. The mass of earthworm had a relatively flat changing rate with the co-exposure of Cu and chlorpyrifos. Using the addition of probability, the q values of different concentration groups of Cu and chlorpyrifos on the earthworm mass were less than 0.55, which indicated significant antagonistic effect. The joint effect of Cu and chlorpyrifos on the activities of CAT and SOD indicated antagonistic effect in filter paper test, while the effects of co-exposure of Cu and chlorpyrifos on the contents of GSH and MDA showed a synergy effect of low concentrations and antagonism effect of high concentrations.

Progresses of alpine treeline formation mechanism.

CONG Yu, HE Hong-shi, GU Xiao-nan, XU Wen-ru, LIU Kai, ZONG Sheng-wei, DU Hai-bo

2016, 27(9):  3035-3041.  doi:10.13287/j.1001-9332.201609.010

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Alpine treelines represent one of the most distinct vegetation boundaries between canopy closed montane forest and treeless alpine vegetation. This transitional ecotone is highly sensitive to global and regional climate change and is considered as an ideal indicator of such changes. Treeline studies have evolved from morphological description to various hypotheses of treeline formation. Although individual hypothesis may provide reasonable explanation locally, a generalized hypothesis that is applicable on the global scale is still lacking. Temperature is considered the limited factor controlling the distribution of alpine treeline as low temperature restricts biochemical processes of tree growth. However, which particular biochemical processes are affected by low temperature remains unknown. This paper summarized the mechanisms of treeline formation with a focus on how low temperature affects photosynthesis characteristics, nutrient characteristics, non-structural carbohydrate (NSC) and antioxidant system. We also reviewed the key issues and future perspectives in treeline research.

Review of estimation on oceanic primary productivity by using remote sensing methods.

XU Hong-yun, ZHOU Wei-feng, JI Shi-jian

2016, 27(9):  3042-3050.  doi:10.13287/j.1001-9332.201609.034

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Accuracy estimation of oceanic primary productivity is of great significance in the assessment and management of fisheries resources, marine ecology systems, global change and other fields. The traditional measurement and estimation of oceanic primary productivity has to rely on in situ sample data by vessels. Satellite remote sensing has advantages of providing dynamic and eco-environmental parameters of ocean surface at large scale in real time. Thus, satellite remote sensing has increasingly become an important means for oceanic primary productivity estimation on large spatio-temporal scale. Combining with the development of ocean color sensors, the models to estimate the oceanic primary productivity by satellite remote sensing have been developed that could be mainly summarized as chlorophyll-based, carbon-based and phytoplankton absorption-based approach. The flexibility and complexity of the three kinds of models were presented in the paper. On this basis, the current research status for global estimation of oceanic primary productivity was analyzed and evaluated. In view of these, four research fields needed to be strengthened in further stu-dy: 1) Global oceanic primary productivity estimation should be segmented and studied, 2) to dee-pen the research on absorption coefficient of phytoplankton, 3) to enhance the technology of ocea-nic remote sensing, 4) to improve the in situ measurement of primary productivity.

Research advances on regulating soil nitrogen loss by the type of nitrogen fertilizer and its application strategy.

ZHOU Wei, LYU Teng-fei, YANG Zhi-ping, SUN Hong, YANG Liang-jie, CHEN Yong, REN Wan-jun

2016, 27(9):  3051-3058.  doi:10.13287/j.1001-9332.201609.022

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Unreasonable application of nitrogen fertilizer to cropland decreases nitrogen use efficiency of crop. A large amount of nitrogen loss to environment through runoff, leaching, ammonia volati-lization, nitrification-denitrification, etc., causes water and atmospheric pollution, poses serious environmental problems and threatens human health. The type of nitrogen fertilizer and its application rate, time, and method have significant effects on nitrogen loss. The primary reason for nitrogen loss is attributed to the supersaturated soil nitrogen concentration. Making full use of environmental nitrogen sources, reducing the application rate of chemical nitrogen fertilizers, applying deep placement fertilizing method, and applying organic fertilizers with chemical nitrogen fertilizers, are effective practices for reducing nitrogen loss and improving nitrogen use efficiency. It is suggested that deve-loping new high efficiency nitrogen fertilizers, enhancing nitrogen management, and strengthening the monitoring and use of environmental nitrogen sources are the powerful tools to decrease nitrogen application rate and increase efficiency of cropland.