Table of Content

18 January 2017, Volume 28 Issue 1

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Effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter in soil solution in a young Cunninghamia lanceolata plantation.

YUAN Xiao-chun, CHEN Yue-min, YUAN Shuo, ZHENG Wei, SI You-tao, YUAN Zhi-peng, LIN Wei-sheng, YANG Yu-sheng

2017, 28(1):  1-11.  doi:10.13287/j.1001-9332.201701.028

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To study the effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter (DOM) in the forest soil solution from the subtropical Cunninghamia lanceolata plantation, using negative pressure sampling method, the dynamics of DOM in soil solutions from 0-15 and 15-30 cm soil layer was monitored for two years and the spectroscopic features of DOM were analyzed. The results showed that nitrogen deposition significantly reduced the concentration of dissolved organic carbon (DOC), and increased the aromatic index (AI) and the humic index (HIX), but had no significant effect on dissolved organic nitrogen (DON) concentration in both soil layers. There was obvious seasonal variation in DOM concentration of the soil solution, which was prominently higher in summer and autumn than in spring and winter.Fourier-transform infrared (FTIR) absorption spectrometry indicated that the DOM in forest soil solution had absorption peaks in the similar position of six regions, being the highest in wave number of 1145-1149 cm^-1. Three-dimensional fluorescence spectra indicated that DOM was mainly consisted of protein-like substances (Ex/Em=230 nm/300 nm) and microbial degradation products (Ex/Em=275 nm/300 nm). The availability of protein-like substances from 0-15 cm soil layer was reduced in the nitrogen treatments. Nitrogen deposition significantly reduced the concentration of DOC in soil solution, maybe largely by reducing soil pH, inhibiting soil carbon mineralization and stimulating plant growth. In particular, the decline of DOC concentration in the surface layer was due to the production inhibition of the protein-like substances and carboxylic acids. Short-term nitrogen deposition might be beneficial to the maintenance of soil fertility, while the long-term accumulation of nitrogen deposition might lead to the hard utilization of soil nutrients.

Effects of simulated nitrogen deposition on soil microbial biomass carbon and nitrogen in natural evergreen broad-leaved forest in the Rainy Area of West China

ZHOU Shi-xing, ZOU Cheng, XIAO Yong-xiang, XIANG Yuan-bin, HAN Bo-han, TANG Jian-dong, LUO Chao, HUANG Cong-de

2017, 28(1):  12-18.  doi:10.13287/j.1001-9332.201701.014

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To understand the effects of increasing nitrogen deposition on soil microbial biomass carbon (MBC) and nitrogen(MBN), an in situ experiment was conducted in a natural evergreen broad-leaved forest in Ya’an City, Sichuan Province. Four levels of nitrogen deposition were set: i.e., control (CK, 0 g N·m^-2·a^-1), low nitrogen (L, 5 g N·m^-2·a^-1), medium nitrogen (M, 15 g N·m^-2·a^-1), and high nitrogen (H, 30 g N·m^-2·a^-1). The results indicated that nitrogen deposition significantly decreased MBC and MBN in the 0-10 cm soil layer, and as N de-position increased, the inhibition effect was enhanced. L and M treatments had no significant effect on MBC and MBN in the 10-20 cm soil layer, while H treatment significantly reduced. The influence of N deposition on MBC and MBN was weakened with the increase of soil depth. MBC and MBN had obvious seasonal dynamic, which were highest in autumn and lowest in summer both in the 0-10 and 10-20 cm soil layers. The fluctuation ranges of soil microbial biomass C/N were respectively 10.58-11.19 and 9.62-12.20 in the 0-10 cm and 10-20 cm soil layers, which indicated that the fungi hold advantage in the soil microbial community in this natural evergreen broad-leaved forest.

Effects of interference intensity on soil respiration and its components in Castanopsis carlesii forest with artificially assisted regeneration in subtropical China

CHEN Zhong, LIN Cheng-fang, ZHANG Xing-xing, LIN Wei-sheng, LIU Xiao-fei, LI Yi-qing, YANG Yu-sheng

2017, 28(1):  19-27.  doi:10.13287/j.1001-9332.201701.031

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The effects of interference intensity on soil respiration (R_S) and heterotrophic respiration (R_H) were studied in two Castanopsis carlesii forests with artificially assisted regeneration. The results showed that C. carlesii forest decreased the R_S and its components with the increasing interfe-rence intensity, particularly decreased its autotrophic respiration (R_A, 1.75 t C·hm^-2·a^-1) by 40% under high interference than under low interference. Compared with C. carlesii forest under low interference, soil organic carbon, fine root biomass, and annual litterfall biomass of C. carlesii forest were significantly reduced under high interference. Soil temperature could explain the seasonal variations of R_S, R_H, and R_A with 84.7%, 68.3% and 5.1% for the C. carlesii forest under low interference, and with 84.4%, 54.6% and 21.7% for the C. carlesii forest under high interference, respectively. The Q₁₀ values of R_S, R_H and R_A in the C. carlesii forest were 1.75, 1.93, 1.27 under low interference, and 2.46, 2.34, 1.65 under high interference, respectively. Carbon storage and soil respiration of forest ecosystem would decrease with the increasing interference intensity, the responses of soil respiration and its components to environmental change were obvious, and forest ecosystem showed vulnerability. It indicated the difficulty of restoring forest ecosystem with high interference during a short term.

Variation in leaf functional traits of different-aged Robinia pseudoacacia communities and relationships with soil nutrients

DUAN Yuan-yuan, SONG Li-juan, NIU Su-qi, HUANG Ting, YANG Gai-he, HAO Wen-fang

2017, 28(1):  28-36.  doi:10.13287/j.1001-9332.201701.036

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On the basis of various leaf functional traits of different-aged Robinia pseudoacacia communities, as well as the relationships between the traits and soil nutrients, the adaptation strategy of R. pseudoacacia in relation to soil conditions was analyzed in Ansai County, the Loess Plateau, China. The results showed that specific leaf area, leaf area, leaf water content, leaf total nitrogen content and leaf organic carbon content first increased and then decreased with the increasing stand age. The peak values of specific leaf area (279.18 cm²·g^-1), leaf area (12.33 cm²), leaf water content (0.09%), leaf total nitrogen content (33.01 g·kg^-1) and leaf organic carbon content (523.08 g·kg^-1) were obtained at 30 years old. With the increasing stand age, leaf tissue density, leaf total phosphorus content, leaf thickness and stomata density increased, and stomata length and stomata width decreased. Leaf area, specific leaf area, leaf total phosphorus content, leaf water content, leaf thicknessand stomata density were the main indexes based on principal component analysis (PCA), for R. pseudoacacia leaf functional traits responding to the increased stand age. The indexes were correlated with each other, indicating that R. pseudoacacia was capable of changing leaf morphological structure to adapt to environmental changes. Soil total nitrogen content was the main factor influencing leaf area, leaf water content, specific leaf area and stomata length, while soil organic carbon content mainly affected stomata width, leaf tissue density, leaf thickness, leaf total phosphorus content, leaf total nitrogen content and stomata density. Therefore, soil total nitrogen and organic carbon content were main factors that affected leaf functional traits of R. pseu-doacacia in different stand ages. Soil nutrients in R. pseudoacacia communities were improved with the increasing stand age, which eventually affected leaf functional traits. The flexibility of leaf functional traits indicated that R. pseudoacacia communities had great potential to adapt to environmental change in Loess Plateau hilly region.

Dominant species population structure and dynamics of natural secondary forest in Mulan-weichang, China

CHEN Qian, YANG Ye, SHI Chen-yuan, XU Xue-hua

2017, 28(1):  37-46.  doi:10.13287/j.1001-9332.201701.029

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To explicate the structure and dynamics of dominant tree populations of the natural se-condary forest in Mulanweichang, the canopy stratum composition, diameter class structure, static life table, survival curve, mortality curve, survival function and the time series prediction were studied. The results showed that there were 9 populations in canopy stratum, with Acer mono, Quercus mongolica, Tilia mandshurica and Betula platyphylla as the dominant populations. The survival curve of A. mono and T. mandshurica populations approximately belonged to Deevey-Ⅱ type, while that of Q. mongolica population and B. platyphylla population belonged to Deevey-Ⅲ type and Deevey-Ⅱ type, respectively. With the increase of diameter class, the mortality rate curves and the vanishing rate curves of all tree populations changed similarly. The maximum mortality rate and va-nishing rate of A. mono, Q. mongolica and T. mandshurica populations appeared in Ⅳ,ⅠandⅠdiameter class, respectively. B. platyphylla changed little over all diameter classes. The 4 survival functions showed that A. mono, Q. mongolica and T. mandshurica populations declined at early stage, but became relatively stable at intermediate and late stages. The B. platyphylla population had no obvious change. The time series prediction showed that the number of small-sized (Ⅰ-Ⅱ) individuals of B. platyphylla decreased gradually and tended to decline, while the populations of A. mono, Q. mongolica and T. mandshurica were fairly stable. We suspected that A. mono, Q. mongo-lica and T. mandshurica would finally dominate within this natural secondary forest.

Effects of root excision mulched with film on photosynthesis characteristics of poplar shelterbelts in black soil region

CHEN Xi, ZHAO Yu-sen, XIN Ying

2017, 28(1):  47-54.  doi:10.13287/j.1001-9332.201701.033

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Root excision mulched with film is an effective method which can minimize decrease in crop production in negative-effect area. However, the measure may have adverse effects on the cropland shelterbelt. Taking no treatment as CK, the effects of root excisions mulched with film at distance 0.5, 1, 2 and 3 m from the trunk on photosynthesis characteristics of poplar shelterbelts in black soil region were discussed. The results indicated that root excision mulched with film had no significant effect on poplar leaf water content. Early in July, the time of peak and trough in the treatments were earlier than CK. Different treatments of root excision mulched with film made daily average value of net photosynthetic rate of poplar leaves significantly lower than CK, and there were significant difference among different treatments. During August to September, root excision mulched with film induced daily average value of net photosynthetic rate of poplar leaves still lower than CK, but the lowered range was somewhat reduced, root excision mulched with film at the distance 3 m from the trunk had no significant difference from CK. After root excision mulched with film, transpiration curve appeared in many forms. At the distances 2 and 3 m from the trunk, daily average value of transpiration rate of poplar leaves had no significant difference from CK. At the distances 0.5 and 1 m from the trunk, the decrease in transpiration rate in July was greater than that of photosynthetic rate, resulting in the significantly high water use efficiency than CK. Compared with CK, daily dynamics of water use efficiency in the other treatments had no change, however, daily average value of water use efficiency in the other treatments had significant change, and some of the changes were adverse. Comprehensive comparison indicated that root excision mulched with film at the distance 3 m from the trunk had no significant effect on the photosynthetic characteristics of poplar leaves, and this treatment was significantly superior to others.

Hydrological functions of the litters and soil of tropical montane rain forest in Xishuangbanna, Yunnan, China

HU Xiao-cong, HUANG Qian-liang, JIN Liang

2017, 28(1):  55-63.  doi:10.13287/j.1001-9332.201701.018

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A study of the hydrological functions of litters and soil of the tropical montane rain forest in Xishuangbanna was carried out. The results showed that the soil bulk density decreased with the increase of altitude, while the soil total porosity, the noncapillary porosity, the capillary porosity, the maximum soil moisture rate, the maximum water holding capacity, the effective water holding capacity, the soil moisture increased with the increase of altitude with local fluctuation. In addition, the soil moisture in early stage of rainy season, the saturated water content and the effective reservoir space increased with the increasing altitude, and the saturated water content and the effective reservoir space had a significant difference at different altitudes (P<0.05). The soil permeability had a significantly positive correlation to the soil total porosity and non-capillary porosity (P<0.01), moreover, the soil non-capillary porosity had a more significant effect on the soil permeability. The thickness of under-composed layer at different altitudes was half more than that of the total litter thickness, which showed that the under-composed layer > semi-decomposed layer. The total volume of litters and the ratio of the volume of semi-decomposed layer to the total volume of litters increased with the increasing altitude, which indicated that the decomposition speed of litters was slower at a low altitude and faster at a high altitude. The maximum capacity of soil moisture, the maximum rate of soil moisture, the natural moisture rate, the effective rate of interception and the effective capacity of interception increased with the increasing altitude in under-composed layer and semi-decomposed layer, and their values in under-composed layer were higher than those in semi-decomposed layer. However, the depth of effective capacity of interception decreased with the increasing altitude with local fluctuation. Comprehensive analysis demonstrated that the water conservation ability was stronger at a high altitude and weaker at a low altitude. The water holding capacity of litters at different altitudes increased and the water absorption rate of litter decreased with the soaking time, while after 12 hours, the water absorption rate of litters gradually became saturated. Moreover, the water holding capacity of litters at different altitudes and soaking time had a logarithmic relationship, and the relationship between the water absorption rate of litters and soaking time was described by power function. In short, there was a stronger water conservation function at high altitude compared with low altitude of the tropical montane rain forest in Xishuangbanna.

Effects of nitrogen addition and elevated CO₂ concentration on soil dissolved organic carbon and nitrogen in rhizosphere and non-rhizosphere of Bothriochloa ischaemum

XIAO Lie, LIU Guo-bin, LI Peng, XUE Sha

2017, 28(1):  64-70.  doi:10.13287/j.1001-9332.201701.005

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A pot experiment was conducted to study soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in the rhizosphere and non-rhizosphere of Bothriochloa ischaemum in loess hilly-gully region under the different treatments of CO₂ concentrations (400 and 800 μmol·mol^-1) and nitrogen addition (0, 2.5, 5.0 g N·m^-2·a^-1). The results showed that eleva-ted CO₂ treatments had no significant effect on the contents of DOC, dissolved total nitrogen (DTN), DON, dissolved ammonium nitrogen (NH₄⁺-N) and dissolved nitrate nitrogen (NO₃^--N) in the soil of rhizosphere and non-rhizosphere of B. ischaemum. The contents of DTN, DON, and NO₃^--N in the rhizosphere soil were significantly increased with the nitrogen application and the similar results of DTN and NO₃^--N also were observed in the non-rhizosphere of B. ischaemum. Nitrogen application significantly decreased DOC/DON in the rhizosphere of B. ischaemum. The contents of DTN, NO₃^--N and DON in the soil of rhizosphere were significantly lower than that in the non-rhizosphere soil, and DOC/DON was significantly higher in the rhizosphere soil than that in the non-rhizosphere soil. It indicated that short-term elevated CO₂ concentration had no significant influence on the contents of soil dissolved organic carbon and nitrogen. Simulated nitrogen deposition, to some extent, increased the content of soil dissolved nitrogen, but it was still insufficient to meet the demand of dissolved nitrogen for plant growing.

Response of plant leaf traits to microhabitat change in a subalpine meadow on the eastern edge of Qinghai-Tibetan Plateau, China

HOU Yuan, LIU Min-xia, SUN Hui-rong

2017, 28(1):  71-79.  doi:10.13287/j.1001-9332.201701.024

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The response of plant leaf traits in five different slope aspects to microhabitat changes was studied on subalpine meadow in Gannan. The number of plant species was 25, 36, 42, 47 and 49 in the sunny slope, half-sunny slope, west slope, half-negative slope and shady slope, respectively. Soil water content, soil nutrients, soil temperature, illumination and soil pH were significantly different among the different slope aspects. Soil water content had the maximum value in the half-shady slope, and daylight illumination, daily soil temperature and soil pH had the maximum value in the sunny slope. Specific leaf area, leaf dry matter, leaf water content, net photosynthetic rate, transpiration rate and water use efficiency were significantly different among the different slope aspects, indicating plant photosynthesis strategy was different in the different microhabitats. Kobresia humilis and Taraxacum mongolicum were dominant species in the sunny slope. Kobresia humilis, Taraxacum mongolicum, Gueldenstaedtia verna and Polygonum macrophyllum were dominant species in the half-sunny slope and west slope. Potentilla fruticosa, Polygonum macrophyllum and Stellera chamaejasme were dominant species in the half-shady slope and shady slope. Habitat quality led to low biomass in the sunny slope and high biomass in the half-shady slope. Biodiversity and abundance were relatively low in the sunny slope and half-shady slope. Biomass was medium, and biodiversity and abundance were the highest in the west slope.

Ecological stoichiometric characteristics of plants and soil in grassland under different restoration types in Yunwu Mountain, China

FANG Ying, AN Shao-shan, MA Ren-tian

2017, 28(1):  80-88.  doi:10.13287/j.1001-9332.201701.034

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Carbon (C), nitrogen (N) and phosphorus (P) stoichiometry from the aboveground parts of plants, roots, plant litter and soils, as well as their relationships were studied in grassland under four distinct types of vegetation recovery including natural grassland, grassland with shrubs, grassland after grazing exclusion, and abandoned cropland in Yunwu Mountain, China. The results showed that there was significant correlation among the ecological stoichiometric characteristics of soils with the aboveground parts and roots. The relation between the aboveground parts and roots was closer in P concentration than in N concentration. The linkage of plants and soils was closer in N concentration than in P concentration. The ecological stoichiometric relationships between soils and litter as well as between roots and litter were weak. There was no significant difference between the aboveground parts and roots in total C and N storages among four distinct recovery methods. How-ever, the P storage differed greatly among the four recovery types with the maximum of 0.49 g·m^-2 in the abandoned cropland and the minimum value of 0.29 g·m^-2 in the grassland after grazing exclusion. Grazing prohibition duration had minor effects on ecological stoichiometric characteristics. The 12-year-abandoned cropland had lower soil organic C and total N concentration (9.98 and 1.07 g·kg^-1, respectively) compared with natural grasslands (14.27 and 1.55 g·kg^-1, respectively), and this difference of ecological stoichiometric characteristics was caused by the high P concentration in abandoned cropland. The roots N and P concentrations were the lowest in natural grassland with 6.25 and 0.57 g·kg^-1, respectively, due to the greatest amount of root biomass. The N and P concentrations in the grassland with shrubs were relatively lower in the aboveground parts(12.77 and 0.98 g·kg^-1,respectively) while relatively higher in roots (9.30 and 0.77 g·kg^-1, respectively). Overall, the plant composition was the key factor that influenced the ecological stoichiome-tric characteristics of plant communities. The distinctions of the ecological stoichiometric characteristics among different restoration types decreased with the increasing Sorensen index.

Evaluation of cold resistance of four wild Carex speices

YE Yan-ran, WANG Wen-li, ZHENG Cheng-shu, FU De-jing, LIU Hui-wen

2017, 28(1):  89-95.  doi:10.13287/j.1001-9332.201701.035

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Four wild Carex speices (C. rigescens, C. lancifolia, C. leucochlora and C. humilis) collected from Mount Taishan were used as experimental materials. The adaption across the winter and physiological characteristics resistant to cold stress were investigated, semi-lethal temperature (LT₅₀) was calculated and fuzzy subordination method was used to generally evaluate the Carex resistant to cold stress. The results showed that 4 Carex species all survived in the winter safely and restored well to grow in the following spring. The green period of the species was between 260 d and 310 d, and percentage of the withered leaves was between 12% and 95%, the range of LT₅₀ was from -18.65 ℃ to -11.74 ℃. With intensifying cold stress, the contents of MDA, proline (Pro) and soluble protein increased at first and then decreased, while the soluble sugar content increased with the treatment time. C. rigescens with poor cold tolerance showed the early accumulation of MDA, Pro and soluble sugar. The value of soluble protein peaked at the late stage of low tempe-rature stress, and the Carex with stronger cold-resistance showed the smaller value. The SOD activity in the leaves of C. lancifolia was higher than that of the other three species in the beginning of treatments. The cold resistance of four Carex species was in order of C. lancifolia>C. leucochlora>C. humilis>C. rigescens.

Changes of soil physical properties during the conversion of cropland to agroforestry system

WANG Lai, GAO Peng-xiang, LIU Bin, ZHONG Chong-gao, HOU Lin, ZHANG Shuo-xin

2017, 28(1):  96-104.  doi:10.13287/j.1001-9332.201701.027

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To provide theoretical basis for modeling and managing agroforestry systems, the influence of conversion of cropland to agroforestry system on soil physical properties was investigated via a walnut (Juglans regia)-wheat (Triticum aestivum) intercropping system, a wide spreading local agroforestry model in northern Weihe River of loess area, with the walnut and wheat monoculture systems as the control. The results showed that the improvement of the intercropping system on soil physical properties mainly appeared in the 0-40 cm soil layer. The intercropping system could prevent soil bulk density rising in the surface soil (0-20 cm), and the plow pan in the 20-40 cm soil layer could be significantly alleviated. The intercropping system had conti-nuous improvement on soil field capacity in each soil layer with the planting age increase, and the soil field capacity was higher than that of each monoculture system in each soil layer (except 20-40 cm soil layer) since the 5th year after planting. The intercropping system had continuous improvement on soil porosity in each soil layer, but mainly in the 0-20 and 20-40 cm soil layer, and the ratio of capillary porosity was also improved. The soil bulk density, field capacity and soil porosity obtained continuous improvement during the conversion of cropland to agroforestry system, and the improvement on soil physical properties was stronger in shallow soil layer than in deep soil.

Multivariate analysis of relationship between soil nutrient factors and fruit quality characte-ristic of ‘Fuji’ apple in two dominant production regions of China

ZHANG Qiang, LI Min-ji, ZHOU Bei-bei, LI Xing-liang, SUN Jian, ZHANG Jun-ke, WEI Qin-ping

2017, 28(1):  105-114.  doi:10.13287/j.1001-9332.201701.030

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The objective of this experiment is to probe into the influence of soil nutrient contents on fruit quality features of ‘Fuji’ apple, screen major soil nutrient factors affecting fruit quality features, clarify the suitable soil nutrient content for good fruit quality indicators, and to provide theoretical basis in reasonable orchard soil fertilizer application for improving fruit qua-lity in the Circum-Bohai and Loess Plateau apple production regions in China. The soil nutrient contents and ‘Fuji’ fruit qualities were respectively analyzed at 66 commercial ‘Fuji’ apple orchards standard rootstock in the Circum-Bohai and Loess Plateau apple production regions of 22 counties in China from 2010 to 2011. The partial least squares regression (PLS) was used to screen major soil nutrient elements affecting fruit quality, and to establish regression equation of relationship between fruit quality and major soil nutrition factors. Linear programming was used to obtain optimum proposals of soil nutrient elements for good apple quality. The results showed that alkaline hydrolytic N, available P, Ca, Fe, and Zn of soil were significantly higher while pH and available K were significantly lower in Circum-Bohai region than in Loess Plateau apple production region. Soluble solid content in Loess Plateau was higher than in Circum-Bohai; moreover, ratio of soluble solids content and titratable acidity was lower. The soil available B in the Circum-Bohai and Loess Plateau apple production regions had positive effect on fruit mass, and total N had negative effect on fruit firmness. The soluble solid contents in the Circum-Bohai were mainly negatively affected by total N and positively by available B, while positively affected by available Ca and negatively by alkaline hydrolytic N in the Loess Plateau region. The desired soil nutrients for good fruit qualities were high avai-lable B, pH and suitable available K in the Circum-Bohai, and low total N, high alkaline hydrolytic N, available K, Fe and suitable available Zn and B in the Loess Plateau region. It was the key technical measures in soil nutrient management for good fruit quality to increase available B and pH, adjust available K in the Circum-Bohai, and to enhance alkaline hydrolytic N, available K, Fe, and to decrease pH, and adjust available Zn and B in the Loess Plateau region.

Effects of supplementary light with different wavelengths on fruit quality of ‘Ruidu Xiangyu’ grape under promoted cultivation

ZHANG Ke-kun, LIU Feng-zhi , WANG Xiao-di, SHI Xiang-bin, WANG Bao-liang, ZHENG Xiao-cui, JI Xiao-hao, WANG Hai-bo

2017, 28(1):  115-126.  doi:10.13287/j.1001-9332.201701.003

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To study the effects of supplemental lighting with ultraviolet (UV), blue and red-blue lights on quality development of grape berries under protected cultivation to promote early maturing, four-year-old vines of ‘Ruidu Xiangyu’ grape using ‘Beta’ as rootstock were used in this experiment. The results indicated that blue and ultraviolet lights were poor in greenhouse environment. Compared with the control, blue and ultraviolet lights lasting 6 hours at night significantly accele-rated the increase of berry mass, fruit diameter, sugar content and the decrease of acidity content during the grape development, but the effect of red-blue light was not obvious. At the fruit maturation, berries supplemented with the three types of light were heavier, and those treated with the UV light were the heaviest. Additionally, grape berries supplemented with blue light had the highest glucose, fructose and total sugar contents, while the sugar contents in berries supplemented with UV light was lower than that under blue light and higher than that under the red-blue light. Volatile linalool, geraniol, terpineol and nerol reached their peak contents ear-liest in berries supplemented with blue light during the developmental stage. At fruit maturation, berries supplemented with blue light had the highest linalool and citronellol contents, while those with UV light had the highest geraniol, hexanal and E-2-hexenal contents, and supplemented with red-blue light had lower linalool content than the control. Moreover, supplementary light was also beneficial for the accumulation of volatile aldehydes and ketones. In conclusion, blue supplementary light could accelerate the development of grape berries as their sugar content was highest and main terpenes reached their peak contents earliest.Grape berries supplemented with UV light had the largest single berry mass and most abundant volatile compounds, while red-blue light treatment was not so effective on quality improvement.

Response of grain-filling properties and quality of winter wheat to drip irrigation in Xinjiang, China

LEI Jun-jie, ZHANG Yong-qiang, CHEN Xing-wu, ZHANG Ying-hua, XUE Li-hua, QIAO Xu, WANG Zhi-min

2017, 28(1):  127-134.  doi:10.13287/j.1001-9332.201701.001

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To provide theoretical basis for the water-saving, high-yield and good quality cultivation techniques of drip-irrigated winter wheat, the wheat cultivar ‘Xindong 22’ was adopted as the test material, and five irrigation amounts including 3150 (W₁), 3900 (W₂), 4650 (W₃), 5400 (W₄) and 0 (CK) m³·hm^-2 were adopted to investigate effects of drip irrigation amount on grain filling dynamics and quality traits in 2012-2013 and 2013-2014 wheat growing seasons in Xinjiang. Results indicated that the grain-filling dynamics of drip-irrigated winter wheat in different treatments presented the “S” shape curve, and accorded with the Logistic model with high fitting degree. The fast increase period of wheat grain-filling was measured at 12-20 days after anthesis. The maximum filling rate (V_m) increased at first and decreased later with the increase of drip irrigation amount, and was obtained in the treatment W₃ in the two seasons, which was 2.16 g·d ^-1and 2.59 g·d ^-1, respectively. With the increase in drip irrigation amount, the bulk mass, protein content, flour extraction rate, wet gluten content, dough stability time, degree of softening, dough extension resis-tance and draw ratio of the drip-irrigated wheat firstly increased and decreased later, and the maxima of these indexes were measured in W₃. However, the water absorption rate and extensibility of dough initially decreased and then increased, and the minimum was obtained in the treatment of W₃. The sedimentation value increased gradually and the dough development time decreased progressively. Treatment W₃ had the highest grain yield of 8913 kg·hm^-2 in 2013 and 8602 kg·hm^-2 in 2014, which was 25.0%, 14.8%, 4.4%, 35.6% and 12.4%, 2.8%, 1.1%, 33.0% higher than the treatments of W₁, W₂, W₄ and CK in 2013 and 2014, respectively. In conclusion, drip irrigation of 4650 m³·hm^-2 during the whole growing season of winter wheat could realize the target of high-yield and good quality in local natural condition.

Effect of long-term fertilization on winter wheat yield from the dry land under different precipitation patterns

HU Yu-tong, HAO Ming-de, WANG Zhe, FU Wei

2017, 28(1):  135-141.  doi:10.13287/j.1001-9332.201701.016

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Based on 30 years long-term fertilization experiment on the semiarid Loess Plateau in China, we studied the effect of different fertilizer treatments on the winter wheat yield, fertilizer contribution rate (FCR) and precipitation use efficiency (PUE) in different precipitation years (drought, normal and wet years). The result showed that the wheat yield, FCR and PUE were significantly higher in nitrogen + phosphorus (NP) and nitrogen + phosphorus +potassium (NPK) treatments than in control (CK) and phosphorus (P) treatments when winter wheat was planted for 30 consecutive years. The wheat yield, FCR and PUE in NPK treatment were highest, with values of 3480 kg·hm^-2, 61.45 kg·kg^-1 and 6.13 kg·mm^-1·hm^-2, respectively, and those in the wet years were higher than in drought and normal years. The stepwise regression analysis showed that wheat yield was mainly influenced by the amount of nitrogen, phosphorus input and precipitation during fallow period and wintering period. Accordingly, increasing nitrogen and phosphorus input accompanying with potassium and water conservation practices during the fallow period could improve the wheat yield on the semiarid Loess Plateau in China.

Effects of tillage and nitrogen application rate on soil nitrogen transformation and yield in a winter wheat/summer maize multiple cropping system

DING Shi-jie, XIONG Shu-ping, MA Xin-ming, ZHANG Juan-juan, WANG Xiao-chun,WU Yi-xin, DU Pan, ZHANG Jie

2017, 28(1):  142-150.  doi:10.13287/j.1001-9332.201701.012

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In the winter-wheat and summer-maize multiple cropping system in lime concretion black soil of Huanghuaihai Plain, the effects of three tilling methods (conventional tillage, rotary tillage, subsoiling tillage) in wheat season coupling with three nitrogen treatments (120 kg·hm^-2, 225 kg·hm^-2, 330 kg·hm^-2) before maize sowing on the activities of microorganisms and enzymes re-lated nitrogen transformation, and inorganic nitrogen content in the rhizosphere soil during the main growth stages of maize, as well as the yield were investigated. The results showed that the rotary tillage had the highest ammonification intensity, and the more nitrogen was put in, the higher were the activities of microorganisms and enzymes related to soil nitrogen transformation. The activities of nitrification, denitrification and urease of subsoiling tillage was significantly higher than those of conventional and rotary tillage. Furthermore, in subsoiling tillage treatment, increasing nitrogen fertili-zer could promote soil nitrogen transformation while excessive nitrogen input inhibited soil nitrogen transformation, though the latter had higher yield and soil inorganic nitrogen content. The treatment of subsoiling tillage coupling with 225 kg·hm^-2 nitrogen, was best for soil nitrogen transformation while the treatment of subsoiling tillage coupling with 330 kg·hm^-2 nitrogen, had the highest corn yield.

Effects of long-term fertilization on nitrogen fertilizer use efficiency in loessial soil region on the Loess Plateau, Northwest China

E Sheng-zhe, YANG Zhi-qi, ZENG Xi-bai, WANG Ya-nan, LUO Zhao-xia, YUAN Jin-hua, CHE Zong-xian, GUO Yong-jie

2017, 28(1):  151-158.  doi:10.13287/j.1001-9332.201701.011

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Nitrogen fertilizer use efficiency is a key parameter to determine recommended nitrogen fertilizer amount and evaluate the effects of nitrogen fertilizer application. The effects of long-term fertilization on annual and accumulated nitrogen fertilizer use efficiency and the relationship between them were studied using a 34-year fertilization experiment (1981-2015) in loessial soil region. The results showed that fertilization had significant influence on annual and accumulated nitrogen ferti-lizer use efficiency of wheat, rape and flax in the period of 1983-2015. The highest mean annual nitrogen fertilizer use efficiency of wheat was achieved in N, P and K combination (NPK), thesecond was N combined with P (NP), 77.7% and 62.0% higher than N application alone respectively. The highest mean annual nitrogen fertilizer use efficiency of rape was achieved in NPK, the second was manure (M), N, P and K combination (MNPK), 93.7% and 65.6% higher than N application alone respectively. The annual nitrogenfertilizer use efficiency of M combined with N (MN) increased significantly compared with N application alone. The annual nitrogen fertilizer use efficiency of M, N and P combination (MNP) decreased significantly compared with NP. The annual nitrogen fertilizer use efficiency of MNPK decreased significantly compared with NPK.There was significant positive linear relationship between annual nitrogen fertilizer use efficiency and crop yield. The correlation between accumulated nitrogen fertilizer use efficiency and crop yield was not significant. It indicated that the annual nitrogen fertilizer use efficiency could be more effective in representing fertilizer use efficiency characteristics under given soil fertility levels, crop varieties and environmental conditions compared with accumulated nitrogen fertilizer use efficiency.

Response of photosynthetic characteristics and accumulation and distribution of assimilation products in tobacco to different light environments

WEI Ming-yue, YUN Fei, LIU Guo-shun, SONG Liang

2017, 28(1):  159-168.  doi:10.13287/j.1001-9332.201701.010

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In order to reveal the photosynthetic characteristics and the mechanism about accumulation and distribution of photosynthetic assimilation products under different light environments, potted tobacco was cultivated in a climate control chamber, there were three light intensity treatments (shading: (400±15)-(500±15) μmol·m^-2·s^-1; natural light: (800±15)-(1000±15) μmol·m^-2·s^-1; high light: (1500±15)-(1800±15) μmol·m^-2·s^-1). The results showed that with the decrease of light intensity, the biomass and root allocation, the net photosynthetic rate (P_n), stomata conductance (g_s) and transpiration rate (T_r) were decreased, but the intercellular CO₂ concentration (C_i) increased. The maximum net photosynthetic rate (A_max), light saturation point (LSP), light saturation point (LCP) and dark respiration rate (R_d) reached the maximum level under high light condition while the apparent quantum efficiency was higher in low light environment. The effects of light intensity on the absorption, accumulation and distribution of ¹³C in tobacco were significant, with a reduced proportion of enriched ¹³C distributed to the root under shading. The changes in the external light environment not only significantly affected the photosynthetic cha-racteristics and biomass accumulation of tobacco leaves, but also the distribution pattern of photosynthetic carbon in tobacco plant-soil system.

Influences of different irrigation amounts on carbon sequestration in wheat-maize rotation system

LIU Jing-jing, ZHANG A-feng, FENG Hao, ZOU Xiao-yang, CHEN Hai-xin

2017, 28(1):  169-179.  doi:10.13287/j.1001-9332.201701.004

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Irrigation can influence greenhouse gas (GHG) emission and carbon footprint in agricultural production. In this study, annual GHG emissions (including CO₂, CH₄, and N₂O) were monitored with static opaque chamber and gas chromatography from a wheat-maize rotation system under different irrigation treatments in the Guanzhong Plain of China during 2014-2015. A total of four different irrigation treatments were conducted, e.g. W₀, W₁₂₀, W₁₈₀, and W₂₄₀, where the subscripts represented the irrigation amounts in mm. Net global warming potential (NGWP) and carbon footprint were used to evaluate the influence of different irrigation amounts on GHG emission and composition of carbon footprint of crop production. Compared with treatment W₀, wheat yield of treatments W₁₂₀, W₁₈₀, and W₂₄₀ increased by 31.3%, 44.3% and 33.7%, while corn yield increased by 9.9%, 22.6%, and 33.8%, respectively. Similarly, annual CO₂ emission increased by 22.2%, 24.3% and 15.1% and annual N₂O emission by 18.6%, 67.8%, and 91.5%, respectively, while annual CH₄ absorption decreased by 51.7%, 79.6% and 97.8%, respectively. The values of NGWP increased by 20.1%, 31.6%, and 31.4%, respectively. The carbon footprint of treatment W₁₂₀ was 19.1% lower than that of W₀, while W₁₈₀ and W₂₄₀ showed no significant difference. Treatments W₁₂₀ and W₂₄₀ increased carbon footprint per unit crop yield by 44.5% and 23.3%, respectively, while W₁₈₀ showed no significant difference. Considering both the economic and environmental effects of different irrigation amounts, we recommend the irrigating amount of 180 mm for the wheat-maize rotation system in the Guanzhong Plain of China for the purposes of water saving and carbon sequestration.

Characteristics of water and heat fluxes and its footprint climatology on farmland in low hilly region of red soil

LI Yang, JING Yuan-shu, QIN Ben-ben

2017, 28(1):  180-190.  doi:10.13287/j.1001-9332.201701.032

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The analysis of the characteristics and footprint climatology of farmland water and heat fluxes has great significance to strengthen regional climate resource management and improve the hydrothermal resource utilization in the region of red soil. Based on quality controlled data from large aperture scintillometer and automatic meteorological station in hilly region of red soil, this paper analyzed in detail the characteristics of farmland water and heat fluxes at different temporal scales and the corresponding source area distribution of flux measurement in the non-rainy season and crop growth period in hilly region of red soil. The results showed that the diurnal variation of water and heat fluxes showed a unimodal trend, but compared with the sunny day, the diurnal variation curves fluctuated more complicatedly on cloudy day. In the whole, either ten-day periods or month scale, the water and heat fluxes were greater in August than in September, while the net radiation flux was more distributed to latent heat exchange. The proportion of net radiation to latent heat flux decreased in September compared to August, but the sensible heat flux was vice versa. With combined effects of weather conditions (particularly wind), stability, and surface condition, the source areas of flux measurement at different temporal scales showed different distribution characteristics. Combined with the underlying surface crops, the source areas at different temporal scales also had different contribution sources.

Ecological regionalization of national cotton fiber quality in China using GGE biplot analysis method

XU Nai-yin, JIN Shi-qiao, LI Jian

2017, 28(1):  191-198.  doi:10.13287/j.1001-9332.201701.017

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The distinctive regional characteristics of cotton fiber quality in the major cotton-producing areas in China enhance the textile use efficiency of raw cotton yarn by improving fiber quality through ecological regionalization. The “environment vs. trait” GGE biplot analysis method was adopted to explore the interaction between conventional cotton sub-regions and cotton fiber quality traits based on the datasets collected from the national cotton regional trials from 2011 to 2015. The results showed that the major cotton-producing area in China were divided into four fiber quality ecological regions, namely, the “high fiber quality ecological region”, the “low micronaire ecological region”, the “high fiber strength and micronaire ecological region”, and the “moderate fiber quality ecological region”. The high fiber quality ecological region was characterized by harmonious development of cotton fiber length, strength, micronaire value and the highest spinning consistency index, and located in the conventional cotton regions in the upper and lower reaches of Yangtze River Valley. The low micronaire value ecological region composed of the northern and south Xinjiang cotton regions was characterized by low micronaire value, relatively lower fiber strength, and relatively high spinning consistency index performance. The high fiber strength and micronaire value ecological region covered the middle reaches of Yangtze River Valley, Nanxiang Basin and Huaibei Plain, and was prominently characterized by high strength and micronaire value, and moderate performance of other traits. The moderate fiber quality ecological region included North China Plain and Loess Plateau cotton growing regions in the Yellow River Valley, and was characterized by moderate or lower performances of all fiber quality traits. This study effectively applied “environment vs. trait” GGE biplot to regionalize cotton fiber quality, which provided a helpful reference for the regiona-lized cotton growing regions in terms of optimal raw fiber production for textile industry, and gave a good example for the implementation of similar ecological regionalization of other crops as well.

Integrated assessment of ecosystem quality of arid inland river basin based on RS and GIS: A case study on Shiyang River Basin, Northwest China

LIANG Bian-bian, SHI Pei-ji, WANG Wei, TANG Xiao, ZHOU Wen-xia, JING Ye

2017, 28(1):  199-209.  doi:10.13287/j.1001-9332.201701.019

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The Shiyang River Basin is an important ecological area of the Eastern Hexi Corridor, and is one of the most prominent areas of water conflict and ecological environment problems. An assessment of ecosystem quality in the Shiyang River Basin can provide a reference for ecological protection in arid inland basin. Based on the concept of ecosystem quality and the statistical yearbook, remotely sensed and land cover data, an evaluation index was established with consideration of three aspects of ecosystem (i.e., productivity, stability and bearing capacity). Kruskal-Wallis (χ²) test and entropy method were applied to determine the weights of evaluation index. With the assistance of RS, GIS and SPSS software, a comprehensive evaluation and change analysis of ecosystem quality and corresponding index were conducted for various ecosystem types in the Shiyang River Basin in 2000, 2005, 2010 and 2015. Results showed that the average ecosystem quality of the Shiyang River Basin was 57.76, and presented an obvious decrease with a magnitude of 0.72 per year du-ring 2000-2015. The spatial pattern of ecosystem quality was that the upstream was better than the midstream, and the midstream was superior to the downstream. The mean values of production capacity, stability and carrying capacity of ecosystem were 67.52, 45.37, and 58.53, respectively. Production capacity and stability had increased slightly, while carrying capacity gradually decreased. Considering various ecosystem types, the highest quality was detected for forest ecosystem with average annual value of 78.12, and this ecosystem presented the lowest decreasing magnitude of 0.28 per year; for grassland, farmland and urban ecosystems, the average annual value was 62.45, 58.76 and 50.29, respectively; the quality of wetland ecosystem was the lowest, and suffered the largest decline with an average rate of 0.98 per year.

Drivers of human-caused fire occurrence and its variation trend under climate change in the Great Xing’an Mountains, Northeast China

LI Shun, WU Zhi-wei, LIANG Yu, HE Hong-shi

2017, 28(1):  210-218.  doi:10.13287/j.1001-9332.201701.037

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The Great Xing’an Mountains are an important boreal forest region in China with high frequency of fire occurrences. With climate change, this region may have a substantial change in fire frequency. Building the relationship between spatial pattern of human-caused fire occurrence and its influencing factors, and predicting the spatial patterns of human-caused fires under climate change scenarios are important for fire management and carbon balance in boreal forests. We employed a spatial point pattern model to explore the relationship between the spatial pattern of human-caused fire occurrence and its influencing factors based on a database of historical fire records (1967-2006) in the Great Xing’an Mountains. The fire occurrence time was used as dependent variable. Nine abiotic (annual temperature and precipitation, elevation, aspect, and slope), biotic (vegetation type), and human factors (distance to the nearest road, road density, and distance to the nearest settlement) were selected as explanatory variables. We substituted the climate scenario data (RCP 2.6 and RCP 8.5) for the current climate data to predict the future spatial patterns of human-caused fire occurrence in 2050. Our results showed that the point pattern progress (PPP) model was an effective tool to predict the future relationship between fire occurrence and its spatial covariates. The climatic variables might significantly affect human-caused fire occurrence, while vegetation type, elevation and human variables were important predictors of human-caused fire occurrence. The human-caused fire occurrence probability was expected to increase in the south of the area, and the north and the area along the main roads would also become areas with high human-caused fire occurrence. The human-caused fire occurrence would increase by 72.2% under the RCP 2.6 scenario and by 166.7% under the RCP 8.5 scenario in 2050. Under climate change scenarios, the spatial patterns of human-caused fires were mainly influenced by the climate and human factors.

Site selection of nature reserve based on the self-learning tabu search algorithm with space-ecology set covering problem: An example from Daiyun Mountain, Southeast China

HUANG Jia-hang, LIU Jin-fu, LIN Zhi-wei, ZHENG Shi-qun, HE Zhong-sheng, ZHANG Hui-guang, LI Wen-zhou

2017, 28(1):  219-230.  doi:10.13287/j.1001-9332.201701.0026

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Designing the nature reserves is an effective approach to protecting biodiversity. The traditional approaches to designing the nature reserves could only identify the core area for protecting the species without specifying an appropriate land area of the nature reserve. The site selection approaches, which are based on mathematical model, can select part of the land from the planning area to compose the nature reserve and to protect specific species or ecosystem. They are useful approaches to alleviating the contradiction between ecological protection and development. The existing site selection methods do not consider the ecological differences between each unit and has the bottleneck of computational efficiency in optimization algorithm. In this study, we first constructed the ecological value assessment system which was appropriated for forest ecosystem and that was used for calculating ecological value of Daiyun Mountain and for drawing its distribution map. Then, the Ecological Set Covering Problem (ESCP) was established by integrating the ecological values and then the Space-ecology Set Covering Problem (SSCP) was generated based on the spatial compactness of ESCP. Finally, the STS algorithm which possessed good optimizing performance was utilized to search the approximate optimal solution under diverse protection targets, and the optimization solution of the built-up area of Daiyun Mountain was proposed. According to the experimental results, the difference of ecological values in the spatial distribution was obvious. The ecological va-lue of selected sites of ESCP was higher than that of SCP. SSCP could aggregate the sites with high ecological value based on ESCP. From the results, the level of the aggregation increased with the weight of the perimeter. We suggested that the range of the existing reserve could be expanded for about 136 km² and the site of Tsuga longibracteata should be included, which was located in the northwest of the study area. Our research aimed at providing an optimization scheme for the sustai-nable development of Daiyun Mountain nature reserve and the optimal allocation of land resource, and a novel idea for designing the nature reserve of forest ecosystem in China.

Urban expansion and vegetation changes in Hangzhou Bay area using night-light data

DONG Chen-wei, CAO Yu, TAN Yong-zhong

2017, 28(1):  231-238.  doi:10.13287/j.1001-9332.201701.022

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Based on DMSP/OLS night-light data and MODIS NDVI data for 2000, 2007 and 2013, this paper studied on characteristics of urban expansion and vegetation changes in built-up areas with nighttime light threshold extraction and vegetation index analysis using remote sensing and GIS. Results showed that the threshold method could realize the effective extraction of urban land information. In general, the urban built-up area expanded along with Hangzhou Bay in V model, and there were three expansion patterns: polygon pattern, linear pattern and point pattern. Obvious spatio-temporal variations in different cities were found in the rate and the dynamic degree of urban expansion and the compactness of urban morphology. The whole study area showed a decreasing trend in the rate and the dynamic degree of urban expansion, while the average compactness of urban morphology declined after the rise. Vegetation conditions became better in built-up areas except Jiaxing in 2000-2007, but it became worse in all cities in 2007-2013. Urban expansion had a ne-gative effect on the vegetation change in built-up areas in 2000-2013.

Protection value evaluation of national wetland parks in Hunan Province, China

WU Hou-jian, DAN Xin-qiu, LIU Shi-hao, HUANG Yan, SHU Yong, CAO Hong, WU Zhao-bai

2017, 28(1):  239-249.  doi:10.13287/j.1001-9332.201701.023

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This paper put forward an evaluation index system which included 5 aspects such as ecological location and representation, biodiversity, species rarity, naturality, scale and partition suitability as well as 15 indicators to assess the protection values of 60 national wetland parks in Hunan Province, China. Analytic hierarchy process (AHP) and entropy method were used in this evaluation index system. There were 37 national wetland parks (accounting for 61.7%) keeping high protection values with scores of greater than or equal to 67.64 points, and 12 national wetland parks (accounting for 20.0%) keeping very high protection values with scores of greater than or equal to 77.72 points. Although there was a discrete and rare regularity of the inter-annual variation, these values still showed a decreasing trend in general. From the space point of view, 70 points isogram divided the national wetland parks of Hunan Province into two high score areas and three high score points in the west and east area, and one low score area and four low score points in the middle. Ecological location, resource endowment and scale were the decisive factors for the conservation va-lues of national wetland parks in Hunan Province.

Remote sensing detection of vegetation health status after ecological restoration in soil and water loss region

HU Xiu-juan, XU Han-qiu, GUO Yan-bin, ZHANG Bo-bo

2017, 28(1):  250-256.  doi:10.13287/j.1001-9332.201701.020

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This paper proposed a vegetation health index (VHI) to rapidly monitor and assess vegetation health status in soil and water loss region based on remote sensing techniques and WorldView-2 imagery. VHI was constructed by three factors, i.e., the normalized mountain vegetation index, the nitrogen reflectance index and the reflectance of the yellow band, through the principal component transformation, in order to avoid the deviation induced by subjective method of weighted summation. The Hetian Basin of Changting County in Fujian Province, China, was taken as a test area to assess the vegetation health status in soil and water loss region using VHI. The results showed that the VHI could detect vegetation health status with a total accuracy of 91%. The vegetation of Hetian Basin in good, moderate and poor health status accounted for 10.1%, 49.2% and 40.7%, respectively. The vegetation of the study area was still under an unhealthy status because the soil was poor and the growth of newly planted vegetation was not good in the soil and water loss region.

Spatiotemporal dynamics of atmospheric PM_2.5 and PM₁₀ and its influencing factors in Nanchang, China

SU Wei, ZHANG Shuai-jun, LAI Xin-yun, GU Xin-ren, LAI Sheng-nan, HUANG Guo-xian, ZHANG Zhi-jian, LIU Yuan-qiu

2017, 28(1):  257-265.  doi:10.13287/j.1001-9332.201701.025

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PM_2.5 and PM₁₀ have become the primary pollutants of most cities in China. Atmospheric PM_2.5 and PM₁₀ mass concentrations, meteorological factors, traffic flow from 2013 to 2015 in Nanchang were analyzed. Spatiotemporal dynamic pattern of atmospheric particulate matter pollution and the effect of weather and traffic on particle concentration change were discussed in this paper. The results showed that PM_2.5(70.92 μg·m^-3 in 2013 > 53.70 μg·m^-3 in 2014 ＞ 43.65 μg·m^-3 in 2015) and PM₁₀(119.72 μg·m^-3 in 2013 ＞ 86.11 μg·m^-3 in 2014 ＞ 73.32 μg·m^-3 in 2015) concentrations decreased gradually from 2013 to 2015. In addition, low concentrations of PM_2.5 and PM₁₀ in summer (average PM_2.5 concentration 36.74 μg·m^-3, average PM₁₀ concentration 69.20 μg·m^-3) but high concentrations in winter (average PM_2.5 concentration 74.29 μg·m^-3, average PM₁₀ concentration 111.64 μg·m^-3) were observed. Moreover, PM_2.5 and PM₁₀ concentrations changed with the urban-rural gradient, decreasing from the city center to suburb. The ratio of PM_2.5/PM₁₀(0.595 ＞ 0.584 ＞ 0.557) decreased year by year from 2013 to 2015 and was higher in the city center area than in the edge of city. PM_2.5 and PM₁₀ concentrations were affected by various meteorological factors and significantly related to air pressure, temperature, relative humidity, wind speed, precipitation and sunshine time. The influence of meteorological factors differed on PM_2.5 and PM₁₀ concentrations. Traffic flow significantly increased the surrounding PM_2.5 concentration, but not PM₁₀ concentration.

Retention and resuspension of atmospheric particles with two common urban greening trees

QIAO Guan-hao, CHEN Jing-wei, LIU Xiao-yu, TAN Lian-shuai, ZHENG Gui-ling, LI Peng

2017, 28(1):  266-272.  doi:10.13287/j.1001-9332.201701.009

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The purification mechanisms of plant leaves with atmospheric particles include adsorption, resuspension, rainwater leaching and absorption. However, few studies focused on the resuspension process of atmospheric particles suspending on the surface of leaves, and the correlation between content of adsorbed particles and content of elements in the leaves. Therefore, two common greening tree species, Platanus acerifolia and Magnolia grandiflora, were selected to analyze the atmospheric particles contents on the leaf surface, the leaf mineral element content, and the resuspension ratios. The results showed that the adsorption capacity of P. acerifolia (4.98 g·m^-2) was higher than that of M. grandiflora (2.65 g·m^-2), which might be connected with rough leaves and dense hairs. The selected 15 elements were all detected by ICP on the leaf surface and in the leaves of two species. In general, the elemental values of the leaf surface were positively related with those in the leaves. However, the two plants showed different selective absorption capacities because positive relation between element adsorption and absorption was only found for Cr, Fe and V for P. ace-rifolia, while such relation was only not found for K, Mn, Si, Ti and Zn for M. grandiflora. The results implied that the absorption was of high selectivity to different elements. Moreover, both increase in wind speed and exposure duration in the wind significantly enhanced resuspension ratios of atmospheric particles. We suggested that resuspension should be taken into account of assessing the relationship between the atmospheric particles deposition and associated plants’ function in the future.

Application of extended exergy method in driving mechanism and efficiency of regional eco-economy

FAN Xin-gang, MI Wen-bao, HOU Jing-wei

2017, 28(1):  273-280.  doi:10.13287/j.1001-9332.201701.008

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To analyze social-economic causes of the regional ecological degradation, and avoid such problems as the complex circulation network and difficulty to identify laws caused by extended exergy analysis (EEA) previously applied at the national scale, this paper reduced spatial scale to the county scale and took Pengyang County in Ningxia as an example. Eco-economic system in Peng-yang County was divided into seven interrelated sectors. The exergy value of circulations in the eco-economic system including materials, labor and capital were calculated respectively to analyze the extended exergy characteristics of the driving sectors, factors and paths and evaluate their ecological efficiency. The results showed that agriculture and households were the main driving sectors of the eco-economic system in Pengyang County. The average exergy value of 31 flow paths among the sectors was 0.80 PJ. There were only 8 flow paths whose exergy values were higher than the average value. Eco-economic system in Pengyang County development was driven by two continuous flow paths, labor output of the households sector and demands of the households sector supported by other sectors. The mineral resources were massively exploited, and then directly exported to the outside, which could not promote the local development from the inside, but, on the contrary, increase the ecological environment pressure because of the over-exploitation. The eco-efficiency of Pengyang County in 2014 was 68.1%, almost equivalent to the by-level of the national scale at home and abroad ten years ago, mainly because of the lower eco-efficiencies of the service sector and households sector. EEA had the advantage of networking and structuring, could specify the sectors, factors and driven paths, and break through the bottleneck of driving mechanism research of the eco-economic system. EEA had certain adaptability to explore the operational principle and optimal pattern of the regional eco-economic system. Compared with the national scale, EEA at the regional scale could more easily identify the driving mechanism of eco-economic system, and could clearly guide the regional administrative department to reduce the ecological environment pressure.

Relationship between fishing grounds temporal-spatial distribution of Thunnus obesus and thermocline characteristics in the Western and Central Pacific Ocean

YANG Sheng-long, WU Yu-mei, ZHANG bian-bian, ZHANG Yu, FAN Wei, JIN Shao-fei, DAI Yang

2017, 28(1):  281-290.  doi:10.13287/j.1001-9332.201701.013

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A thermocline characteristics contour on a spatial overlay map was plotted using data collected on a monthly basis from Argo buoys and data of monthly CPUE (catch per unit effort) bigeye tuna (Thunnus obesus) long-lines fishery from the Western and Central Pacific Fisheries Commission (WCPFC) to evaluate the relationship between fishing grounds temporal-spatial distribution of bigeye tuna and thermocline characteristics in the Western and Central Pacific Ocean (WCPO). In addition, Numerical methods were used to calculate the optimum ranges of thermocline characteristics of the central fishing grounds. The results showed that the central fishing grounds were mainly distributed between 10° N and 10° S. Seasonal fishing grounds in the south of equator were related to the seasonal variations in the upper boundary temperature, depth and thickness of thermocline. The fishing grounds were observed in areas where the upper boundary depth of thermocline was deep (70-100 m) and the thermocline thickness was more than 60 m. The CPUE tended to be low in area where the thermocline thickness was less than 40 m. The optimum upper boundary temperature range for distribution was 26-29 ℃, and the CPUE was mostly lower than the threshold value (Q3) of central fishing grounds when the temperature was higher than 29 ℃ or lower than 26 ℃. The temporal and spatial distribution of the fishing grounds was influenced by the seasonal variations in upper boundary depth and thermocline thickness. The central fishing grounds in the south of equator disappeared when the upper boundary depth of thermocline decreased and thermocline thickness became thinner. The lower boundary temperature and depth of thermocline and thermocline strength has little variation, but were strongly linked to the location of fishing grounds. The fishing grounds were mainly located between the two high-value zones of the lower boundary depth of thermocline, where the temperature was lower than 13 ℃ and the strength was high. When the depth was more than 300 m or less than 150 m, the lower boundary temperature was more than 17 ℃, or the strength was low, the CPUE tended to be low. The optimum range of thermocline characteristics was calculated using frequency analysis and empirical cumulative distribution function. The results showed that the optimum ranges for upper boundary thermocline temperature and depth were 26-29 ℃ and 70-110 m, the optimum lower boundary thermocline temperature and depth ranges were 11-13 ℃ and 200-280 m, the optimum ranges for thermocline thickness and thermocline strength were 50-90 m and 0.1-0.16 ℃·m^-1, respectively. The paper documented the distribution interval of thermocline characteristics for central fishing ground of the bigeye tuna in WCPO. The results provided a reference for improving the efficiency of pelagic bigeye tuna fishing operation and tuna resource management in WCPO.

Optimal design of sample size for estimating species richness of fishes in Dianshan Lake, China

WANG Jia-qi, DAI Xiao-jie, WANG Kun, WANG Hao-zhan, TIAN Si-quan

2017, 28(1):  291-298.  doi:10.13287/j.1001-9332.201701.039

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Sample size plays a significant role in determining accuracy and precision for estimates of fish population dynamics or fish communities. A fisheries survey that estimated the fish community in Dianshan Lake was conducted as a case study to determine the necessary sample size for such estimates. Monthly surveys of 24 survey stations in Dianshan Lake were conducted from July, 2010 to June, 2011, resulting in the collection of 45 fish species from 14 families. A resampling technique was used to estimate the optimal survey times and number of survey stations for a Dianshan Lake fishery survey. Results showed a negative relationship between the number of stations per survey and survey times per year. To maintain a 90% fixed percentage of fish species detection and 95% fixed probability of detection within the fishery survey, the required sample sizes were 19 and 21 stations per survey and 12 and 11 survey times per year, correspondingly. The Shannon diversity index increased with the number of stations before reaching equilibrium, therefore, the optimal survey stations for estimating fish biodiversity of the Dianshan Lake fishery was determined to be 21 stations. This study provided a framework for determining the optimal sampling effort in similar studies at other locations.

Effects of fish on field resource utilization and rice growth in rice-fish coculture

ZHANG Jian, HU Liang-liang, REN Wei-zheng, GUO Liang, WU Min-fang, TANG Jian-jun, CHEN Xin

2017, 28(1):  299-307.  doi:10.13287/j.1001-9332.201701.040

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Rice field can provide habitat for fish and other aquatic animals. Rice-fish coculture can increase rice yield and simultaneously reduce the use of chemicals through reducing rice pest occurrence and nutrient complementary use. However, how fish uses food sources (e.g. phytoplankton, weeds, duckweed, macro-algal and snail) from rice field, and whether the nutrients releasing from those food sources due to fish transforming can improve rice growth are still unknown. Here, we conducted two field experiments to address these questions. One was to investigate the pattern of fish activity in the field using the method of video recording. The other was to examine the utilization of field resources by fish using stable isotope technology. Rice growth and rice yield were also exa-mined. Results showed that fish tended to be more active and significantly expanded the activity range in the rice-fish coculture compared to fish monoculture (fish not living together with rice plants). The contributions of 3 potential aquatic organisms (duckweed, phytoplankton and snail) to fish dietary were 22.7%, 34.8% and 30.0% respectively under rice-fish coculture without feed. Under the treatment with feed, however, the contributions of these 3 aquatic organisms to the fish die-tary were 8.9%, 5.9% and 1.6% respectively. The feed contribution was 71.0%. Rice-fish coculture significantly increased the nitrogen concentration in rice leaves, prolonged tillering stage by 10-12 days and increased rice spike rate and yield. The results suggested that raising fish in paddy field may transform the nutrients contained in field resources to bioavailable for rice plants through fish feeding activity, which can improve rice growth and rice yield.

Effects of different forest stand types of Pinus sylvestris var. mongolica on insect community diversity in Saihanba Nature Reserve, North China

WU Long-fei, JIANG Wen-hu, YUAN Sheng-liang, GUO Meng-meng, LIU Jun-xia

2017, 28(1):  308-314.  doi:10.13287/j.1001-9332.201701.007

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In order to study the effects of different stand types of Mongolian scots pine (Pinus sylvestris var. mongolica) on the diversity of insect community in the plantation under close-to-nature forest management, the structure of the insect community was studied in five stand types of the Mongolian scots pine pure forest and mixed forests in Saihanba Nature Reserve. The insects were collected by the sweep net method, and the diversity index, similarity, principal component, and stability of insect communities in different forest types were analyzed. In total, 9617 insects, belonging to 7 orders, 70 families, 195 species, were collected, and the Diptera, Hemipteran and Coleopteran were the dominant groups. The insect species in 5 stand types were all rich, and the insect community structure among the different stands reached a moderate dissimilar level. The species and individual number of mixed forest was more than those of pure forest. There was no significant difference among different stand types in insect community character indices. Principal component analysis indicated that phytophagous group, predatory group and parasitic group in each stand type were the main factors influencing the community structure, and predatory group and parasitic group had a stronger control effect on phytophagous group. The structure of insect community in the diffe-rent forest stand types had relatively high stability.

Effects and mechanism of two Streptomyces strains on promoting plant growth and increasing grain yield of maize

MA Jun-ni, LIU Yu-tao, LI Yu-long, SUN Yue-yue, YANG Bang-min, LAI Hang-xian, XUE Quan-hong

2017, 28(1):  315-326.  doi:10.13287/j.1001-9332.201701.038

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This paper was mainly to explore the effects of two Streptomyces strains (S. roche D74 and S. pactum Act12) and their mixed actinomycetes agent on maize growth. Petri dish germination test, sand culture trial and plot trial were performed to determine the biological properties, leaf inducible enzyme activities, photosynthesis, ear characteristics, grain yield and quality of maize after seed soaking with acellular culture filtrate of D74 or Act 12 and seed coating with the mixed actinomycetes agent of two Streptomyces stains. The result showed that the seed soaking treatment significantly contributed to hypocotyls, radical and seedling growth, and increased the leaf inducible enzyme activities of maize seedlings. The 1000-fold dilution of D74 improved hypocotyl length, radicle length, and fibrous root number by 43.4%, 26.4%, and 100.7% (P<0.05), respectively, whereas the undiluted solution of D74 improved leaf polyphenol oxidase (PPO) activity by 40.2% (P<0.05). The 1000-fold dilution of Act12 improved hypocotyl length, radicle length, and fibrous root number by 36.3%, 36.3%, and 117.5% (P<0.05), the total fresh mass and root fresh mass by 31.1% and 36.6%, respectively (P<0.05). The 10-fold and 1000-fold dilutions of Act12 improved leaf PPO activity by 38.1% and 39.5%, respectively (P<0.05). The seed coating treatment showed the following significant effects, compared with the control: 1) Improving the root development. 2) Enhancing the leaf photosynthesis. 3) Improving the ear characteristics and grain yield. 4) Promoteing the grain filling. 5) Improving the leaf inducible enzyme activities. The results indicated that seed coating with the mixed actinomycetes agent of two Streptomyces strains could significantly affect the biological characteristics, photosynthesis and biochemical metabolism of maize seedlings, stimulate root development, promote plant growth, and improve grain yield of maize.

Alternative stable states in coastal intertidal wetland ecosystems of Yangtze estuary, China

LI Hui, YUAN Lin, ZHANG Li-quan, LI Wei, LI Shi-hua, ZHAO Zhi-yuan

2017, 28(1):  327-336.  doi:10.13287/j.1001-9332.201701.021

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Alternative stable states phenomenon widely exists in a variety of ecosystems and is closely related to ecosystem health and sustainable development. Although alternative stable states research has become the focus and hotspot of the ecology researches, only a few empirical evidences supported its behavior and mechanisms in coastal wetland ecosystems up to now. In our study, ta-king the intertidal wetland ecosystem in Chongming Dongtan Nature Reserve as study area, we aimed to: 1) test the existence of alternative stable states based on judgment conditions (bimodal characteristic and threshold effect) and determine the relative stable state types; 2) explore the formation mechanisms of alternative stable states by monitoring hydrological conditions, sediment accretion dynamics as well as vegetation growth parameters and analyzing the positive feedbacks between saltmarsh vegetation and sedimentary geomorphology. Our results showed that: 1) Normalized difference vegetation index (NDVI) frequentness distribution revealed obvious bimodality at saltmarsh pioneer zone. Propagule biomass threshold limited the establishment of plant patches representing the “saltmarsh” state. The presence of bimodality and biomass threshold demonstrated there are “mudflat” stable state and “saltmarsh” stable state with distinct structure and function in intertidal wetland ecosystem. 2) Current velocities, turbidities and direction perpendicular to the vegetation zone were the most important factors responsible for the sediments rapid accretion at saltmarsh pioneer zone in spring and summer. Sediments accretion significantly promoted the growth of saltmarsh plant. The positive feedbacks between plant growth and sediments accretion resulted in the formation of alternative stable states. 3) The expansion pattern of saltmarshes in the Chongming Dongtan intertidal wetland ecosystem also suggested that increases of sediments accretion could trigger the formation of “mudflat” stable state and “saltmarsh” stable state on landscape scale. The results from this study could enrich regime shift mechanisms researches and provide the scientific supports for coastal zone protection, restoration and comprehensive management, which could have important theoretical and practical meaning.

Influences of tide on silicon and nitrogen contents in soil and porewater in the Minjiang Ri-ver estuary, Southeast China

HOU Guan-yun, ZHAI Shui-jing, LE Xiao-qing, TONG Chuan

2017, 28(1):  337-344.  doi:10.13287/j.1001-9332.201701.002

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Taking Shanyuntan wetland in the Minjiang River estuary as test object, the dissolved silicates (DSi) and inorganic nitrogen contents in porewater and the biogenic silica (BSi) and total nitrogen contents in surface soil of the Phragmites australis wetland, Cyperus malaccensis wetland and Spartina alterniflora wetland were measured in October 2014 (spring tide month) and April 2015 (neap tide month), respectively, to illuminate the influence of tide on silicon and nitrogen contents in soil and porewater of estuarine wetland. Results showed that the DSi content in porewater and the BSi content in surface soil in spring tide month were slightly higher than those in neap tide month, with the highest being observed on neap tide day and the lowest occurring on spring tide day. In contrast, the BSi content in surface soil on spring tide day showed an opposite trend with that on neap tide day. The contents of NH₄⁺-N and NO₃^--N in porewater of different wetland soils in spring tide month were higher than those in neap tide month, while the content of NH₄⁺-N on spring tide day was significantly higher than that on neap tide day (P<0.05). The study found that hydrological conditions such as flooding duration and drying-wetting alternation caused by tide had great influences on silicon and nitrogen contents in porewater and surface soil, and vegetation types also showed great influences on their distributions in intertidal wetland of the Minjiang River estuary.

Reviews

Recent discovery in nitrification: One-step nitrification and complete ammonia oxidizing microorganisms

DONG Xing-shui, WANG Zhi-hui, HUANG Xue-ru, JIANG Xian-jun

2017, 28(1):  345-352.  doi:10.13287/j.1001-9332.201701.015

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Nitrification is the process of microbial oxidation of ammonia to nitrate, completed by the ammonia oxidizers (AOB and AOA) and nitrite oxidizing bacteria (NOB), sequentially. For a century, we have been learning and studying the established two-step process as the unique way for nitrification. According to the kinetic theory, there should be a one-step nitrification in the environment, that is, the whole process of nitrification (from NH₃ to NO₃^-) was completed by one microorganism, but no study could give a direct proof for the existence of this microorganism. Until the end of 2015, three different cultivated bacteria (Candidatus Nitrospira nitrosa, Candidatus Nitrospira nitrificans and Candidatus Nitrospira inopinata) and an uncultivated bacterium (Nitrospira-like orga-nism) respectively found in different environments by three research teams, were defined as complete ammonia oxidizing microorganisms (Comammox), because all of them could carry out the complete oxidation of ammonia to nitrate. The discovery of one-step nitrification and Comammox ended the 100-year-old dogma, and triggered many important scientific issues of the global nitrogen cycle, such as the ecological niche of these microorganisms in the environment and their relative contribution in nitrification. This paper made a brief overview of the discovery of one-step nitrification and Comammox.

Atmospheric depositions of biogenic elements and their ecological effects on marine ecosystem of Jiaozhou Bay: A review

XING Jian-wei, SONG Jin-ming, YUAN Hua-mao, LI Xue-gang, LI Ning, DUAN Li-qin, QU Bao-xiao, KANG Xu-ming

2017, 28(1):  353-366.  doi:10.13287/j.1001-9332.201701.006

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As a typical semi-closed bay, Jiaozhou Bay, is remarkably affected by human activities. Biogenic elements transported into the oceans by the atmospheric deposition of anthropogenic particles can lead to profound impacts on the ecosystem of Jiaozhou Bay. In this paper, the researches of atmospheric dry and wet depositions in the Jiaozhou Bay were systematically summarized from the following three aspects: study methods, variation characteristics of the fluxes and their influencing factors and the ecological effects of atmospheric deposition. The concentrations and fluxes of nitrogen species in atmospheric dry and wet depositions were very high in the Jiaozhou Bay compared with other bays, estuaries and marginal seas around the world. The dissolved inorganic nitrogen (DIN) was the main component of the total dissolved nitrogen (TDN) and the dissolved organic nitrogen (DON) accounted for 22%-31% of TDN. However, the concentrations and fluxes of phosphate and silicate species were very low. The atmospheric deposition fluxes of (NO₃^--N+NO₂^--N) were slightly higher than terrestrial inputs, while the fluxes of NH₄⁺-N, PO₄^3--P and SiO₃^2--Si were very low compared with terrestrial inputs. The concentration of total suspended particulates (TSP) in the air, the intensity of the emission sources, precipitation amount and meteorological conditions are the major factors influencing the atmospheric depositions of biogenic elements, which can increase the primary productivity, change the structure of nutrients and the structure of phytoplankton communities in surface seawater and further promote the succession of phytoplankton dominant species from diatom to dinoflagellate in the Jiaozhou Bay. On that basis, the future research should be focused on constructing the monitoring network for atmospheric dry and wet depositions, accurately quantifying the deposition rates of aerosol particles of different forms and sizes, recognizing the ecological effects and biogeochemical mechanisms of atmospheric depositions of biogenic elements and discriminating the mechanisms, fluxes and influencing factors of atmospheric deposition biogenic elements via indirect approaches such as overland runoff, sheetflood and permeation etc. It is significant for illuminating the effects of anthropogenic activities on the coastal waters as well as understanding the bio-geochemical processes of biogenic elements in marginal seas by elucidating atmospheric depositions of biogenic elements in the Jiaozhou Bay.