Table of Content

18 October 2016, Volume 27 Issue 10

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CONTENTS

Simulation study on the effects of climate change on aboveground biomass of plantation in southern China: Taking Moshao forest farm in Huitong Ecological Station as an example

DAI Er-fu, ZHOU Heng, WU Zhuo, WANG Xiao-fan, XI Wei-min, ZHU Jian-jia

2016, 27(10):  3059-3069.  doi:10.13287/j.1001-9332.201610.011

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Global climate warming has significant effect on territorial ecosystem, especially on forest ecosystem. The increase in temperature and radiative forcing will significantly alter the structure and function of forest ecosystem. The southern plantation is an important part of forests in China, its response to climate change is getting more and more intense. In order to explore the responses of southern plantation to climate change under future climate scenarios and to reduce the losses that might be caused by climate change, we used climatic estimated data under three new emission scenarios, representative concentration pathways (RCPs) scenarios (RCP2.6 scenario, RCP4.5 scenario, and RCP8.5 scenario). We used the spatially dynamic forest landscape model LANDIS-Ⅱ, coupled with a forest ecosystem process model PnET-Ⅱ, to simulate the impact of climate change on aboveground net primary production (ANPP), species’ establishment probability (SEP) and aboveground biomass of Moshao forest farm in Huitong Ecological Station, which located in Hunan Province during the period of 2014-2094. The results showed that there were obvious differences in SEP and ANPP among different forest types under changing climate. The degrees of response of SEP to climate change for different forest types were shown as: under RCP2.6 and RCP4.5, artificial coniferous forest>natural broadleaved forest>artificial broadleaved forest. Under RCP8.5, natural broadleaved forest>artificial broadleaved forest>artificial coniferous forest. The degrees of response of ANPP to climate change for different forest types were shown as: under RCP2.6, artificial broadleaved forest> natural broadleaved forest>artificial coniferous forest. Under RCP4.5 and RCP8.5, natural broadleaved forest>artificial broadleaved forest>artificial coniferous forest. The aboveground biomass of the artificial coniferous forest would decline at about 2050, but the natural broadleaved forest and artificial broadleaved forest showed a rising trend in general. During the period of 2014-2094, the total aboveground biomass under RCP2.6, RCP4.5 and RCP8.5 scenarios increased by 68.2%, 79.3% and 72.6%, respectively. The total aboveground biomass under various climatic scenarios sort as: RCP4.5>RCP8.5>RCP2.6. We thought that an appropriate temperature might be beneficial to the biomass accumulation in this study area. However, overextended temperature might hinder the sustainable development of forest production and ecological function.

Estimation and spatial-temporal pattern of forest aboveground biomass and NPP in Heihe Region, Heilongjiang Province, China

ZHAO Ying-hui, LI Si-qi, ZHEN Zhen, LI Feng-ri, WEI Qing-bin

2016, 27(10):  3070-3080.  doi:10.13287/j.1001-9332.201610.023

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Based on 1390 fixed plots data collected in 2005 and 2010 in Heihe Region of Heilongjiang Province, biomass allometric models of tree species in northeastern China were applied to calculate aboveground biomass (AGB) and net primary productivity (NPP). Based on ETM⁺ ima-geries in 2005 and 2010, Kriging and co-Kriging methods in geostatistics were applied to interpolate AGB and NPP and different variogram models were compared. The distribution maps of AGB and NPP were produced using the best interpolation method. The change of AGB and NPP over time and space and the impacts of stand types and terrain factors (aspect, slope and altitude) on the distributions of AGB and NPP were analyzed by comparing the distribution maps in different years. The results indicated that AGB had an increasing trend and areas with AGB higher than 40 t·hm^-2 also increased. However, NPP decreased from 2005 to 2010. Some high NPP regions were changed into low NPP regions. AGB and NPP were correlated with forest terrain factors, especially altitude, which indicated that the distribution of biomass and NPP were highly influenced by altitude. During the study period, AGB increased at all slope aspects while NPP decreased, AGB and NPP had an increasing trend with raised slope degree andaltitude, the AGB and NPP of evergreen coniferous forest increased most, and the AGB of mixed deciduous-coniferous forest and NPP of broad-leaved deciduous forest had the least increase.

Effects of small hydropower substitute fuel project on forest ecosystem services

YU Hai-yan, ZHA Tong-gang, NIE Li-shui, LYU Zhi-yuan

2016, 27(10):  3081-3088.  doi:10.13287/j.1001-9332.201610.026

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Based on the Forest Ecosystem Services Assessment Standards (LY/T 1721－2008) issued by the State Forestry Administration, this paper evaluated four key functions of forest ecosystems, i.e., water conservation, soil conservation, carbon fixation and oxygen release, and nutrient accumulation. Focusing on the project area of Majiang County in Guizhou Province, this study provided some quantitative evidence that the implementation of the small hydropower substituting fuel project had positive effects on the values and material quantities of ecosystem service functions. The results showed that the small hydropower substituting fuel project had a significant effect on the increase of forest ecosystem services. Water conservation quantity of Pinus massoniana and Cupressus funebris plantations inside project area was 20662.04 m³·hm^-2·a^-1, 20.5% higher than outside project area, with soil conservation quantity of 119.1 t·hm^-2·a^-1, 29.7% higher than outside project area, carbon fixation and oxygen release of 220.49 t·hm^-2·a^-1, 40.2% higher than outside project area, and forest tree nutrition accumulation of 3.49 t·hm^-2·a^-1, 48.5% higher than outside project area. Small hydropower substituting fuel project for increasing the quota of forest ecosystem service function value was in the order of carbon fixation and oxygen release function (71400 yuan·hm^-2·a^-1) > water conservation function (60100 yuan·hm^-2·a^-1) > tree nutrition accumulation function (13800 yuan·hm^-2·a^-1) > soil conservation function (8100 yuan·hm^-2·a^-1). Small hydropower substituting fuel project played an important role for improving the forest ecological service function value and realizing the sustainable development of forest.

Competition among dominant tree species in a natural spruce-fir forest in Changbai Mountain

REN Mei-mei, YANG Hua

2016, 27(10):  3089-3097.  doi:10.13287/j.1001-9332.201610.015

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Dominant tree species are the main species in different layers of mixed-species forests. Examining competitive relationships among dominant tree species is important for proper management of mixedwood forests. In this study, we established a 100 m×100 m plot of uniform condition on Jingouling Forest Farm, Wangqing County, Jilin Province. The dominant tree species of the young forest community were first determined through dominance index analysis approach and the competitive relationships among dominant tree species were then examined using tree competition index that described intra- and inter-specific competition from the above and sides of individual tree crown. The results indicated three dominant tree species in this mixed-species community were Abies nephrolepis, Picea koraiensis and Pinus koraiensis. A. nephrolepis, Picea koraiensis, Pinus koraiensis, Betula costata, Tilia amurensis, Acer tegmentosum and Betula platyphylla were the main competitors of the dominant tree species, while A. nephrolepis was the major competitor for all three dominant tree species (1412.48), followed by Picea koraiensis (439.17) and Pinus koraiensis (245.28), they all had side squeeze effect (64.9%, 65.2% and 66.0% of the total competition for the three dominant tree species, respectively). The level of side and above competition decreased with individual tree DBH (diameter at breast height); the percentage of side competition was nearly equal to that of above competition in small trees and increased with tree size, reaching nearly 100% in large canopy trees. For the three dominant tree species, the side and above competition of three dominant tree species mainly came from A. nephrolepis, Picea koraiensis, Pinus koraiensis, T. amurensis, B. costata, A. tegmentosum and B. platyphylla, and the inter-specific competition was more intense than intra-specific competition (58.4%, 87.1%, 83.7% of the total competition for the three dominant species), both of which decreased with the increase of individual tree DBH.

Effects of forest gap size on the growth and form quality of Taxus wallichina var. mairei in Cunninghamia lanceolata forests

OU Jian-de, WU Zhi-zhuang, LUO Ning

2016, 27(10):  3098-3104.  doi:10.13287/j.1001-9332.201610.018

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In order to clarify the effects of forest gap size on the growth and stem form quality of Taxus wallichina var. mairei and effectiveness of the precious timbers cultivation, 25 sample plots in Cunninghamia lanceolata forest gaps were established in Mingxi County, Fujian Province, China to determine the indices of the growth, stem form and branching indices of T. wallichina var. mairei seedlings. The relationships between the gap size and growth, stem form and branching were investigated. The 25 sample plots were located at five microhabitats which were classified based on gap size as follows: ClassⅠ, Ⅱ, Ⅲ, Ⅳ and Ⅴ, which had a gap size of 25-50 m², 50-75 m², 75-100 m², 100-125 m² and 125-150 m², respectively. The evaluation index system of precious timbers was built by using hierarchical analysis. The 5 classes of forest gaps were evaluated comprehensively by using the multiobjective decision making method. The results showed that gap size significantly affected 11 indices, i.e., height, DBH, crown width, forking rate, stem straightness, stem fullness, taperingness, diameter height ratio, height under living branch, interval between branches, and max-branch base diameter. ClassⅠand Ⅱ both significantly promoted the growth of height, DBH and crown width, and both significantly inhibited forking rate and taperingness, and improved stem straightness. ClassⅡ significantly improved stem fullness and diameter height ratio. ClassⅠand Ⅱ significantly improved height under living branch and reduced max-branch base diameter. Class Ⅰ significantly increased interval between branches. ClassⅠandⅡ significantly improved the comprehensive evaluation score of precious timbers. This study suggested that controlled cutting intensity could be used to create forest gaps of 25-75 m², which improved the precious timber cultivating process of T. wallichina var. mairei in C. lanceolata forests.

Distribution patterns of Juglans cathayensis populations at different slope aspects in Tianshan valley in Xinjiang, China

ZHANG Wei, LI Hai-yan, LAI Xiao-hui, YANG Yun-fei

2016, 27(10):  3105-3113.  doi:10.13287/j.1001-9332.201610.004

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Eight 4000 m² plots were set up at eight sites distributed on sunny and shady slopes of four valleys, and adjacent lattice method was used to survey Juglans cathayensis populations. At different scales, aggregation intensity index such as variance/mean ration and deviation index (C_x), negative binomial parameter (K), clumping index (I), mean crowding index (m^*), patchiness index (PAI) and aggregation index (C_a) were used to analyze distribution patterns of populations. With the increase of surveying scales, the distribution patterns changed from cluster to random. Populations presented a clustered distribution when the scale was 25 m². Aggregation intensity had great differences among different plots, and the maximum one located on west shady slope and the minimum one did on south shady slope. However, populations presented a random distribution when the scale was 50-400 m². When scale was 25 m², saplings, young and mature trees showed a clustered distribution. Aggregation intensity of mature trees was the maximum one and that of saplings was the minimum one. When the scale was 200-400 m², saplings, young and mature trees showed random distribution. The pattern size of J. cathayensis populations was 25 m² and pattern intensity was 2.49-9.38 m². The pattern intensity of young trees was the largest and that of mature trees was the least in population components. In a word, when sampling scale was close to population patch size, a reliable conclusion usually could be obtained by using adaptive determination method and multi-index comprehensive decision.

Cold resistance of four evergreen broad-leaved tree species

WANG Na, WANG Kui-ling, LIU Qing-hua, LIU Qing-chao

2016, 27(10):  3114-3122.  doi:10.13287/j.1001-9332.201610.025

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The leaves of four evergreen plants, i.e., Fatsia japonica, Nerium indicum, Mahonia bealei and Acer cinnamomifolium were used as the experimental materials. By measuring the changes of in vitro leaf in soluble sugar, soluble protein, free proline, POD activity, chlorophyll content and relative electrolytic conductivity under aritificial simulated low temperature, combining the measurements of SPAD, leaf surface features and anatomical changes in organizational structure in the process of natural wintering, the cold resistance of four evergreen tree species was evaluated comprehensively. The results showed that in the process of artificial low temperature stress, the chlorophyll content of the leaves of four evergreen species decreased, the content of soluble protein pea-ked at -20 ℃, and the soluble sugar, free proline, POD activity and relative electrolytic conductivity showed an overall upward trend. The semilethal temperatures of four species were -8.0, -13.4, -19.4 and -14.8 ℃, respectively. During the winter, the leaf SPAD of the four species changed markedly, reflecting that the change of relative chlorophyll content was related to the change of temperature. Meanwhile, the leaf thickness, cutin layer thickness, stockade tissue thickness and tightness of four species increased and the plasmolysis occurred thereafter. Also the content of starch grains and calcium oxalate cluster crystal increased. The typical stomatal pits and the intensive non-glandular trichome within the pits of N. indicum and the sclerenchyma of M. Bealei could improve the cold resistance of plants to some extent. In addition, the phenomena like the breakage of wax layer in leaf surface, the fracture of epidermal hair and the deformation of palisade tissue indicated that plants were damaged to a certain extent by low temperature.

Effects of exponential N fertilization on the growth and nutrient content in clonal Cunninghamia lanceolata seedlings

LIU Huan, WANG Chao-qi, WU Jia-sen, GUO Lian-hua

2016, 27(10):  3123-3128.  doi:10.13287/j.1001-9332.201610.027

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A pot experiment was conducted in a greenhouse on one-year-old clonal seedlings of Cunninghamia lanceolata. Five treatments were designed including control, conventional fertilization and three exponential fertilization treatments, with N application rates of 0, 0.5, 0.5, 1.0 and 2.0 g·seedling^-1, with N applied at 20 times at 10-day interval. The height, ground diameter, biomass, chlorophyll fluorescence and N absorption were measured after 210 days of N application. The results showed that fertilization significantly promoted the seedling height, ground diameter and biomass with the optimal values of 59.0 cm, 6.0 mm, 52.99 g·seedling^-1, in exponential fertilization treatment of 1.0 g N·seedling^-1. Chlorophyll fluorescence in exponential fertilization treatments was significantly higher than that in conventional fertilization. The photochemical quenching, PSⅡ electron transport rate and photochemical efficiency of PSⅡ in exponential fertilization treatments increased first and then decreased, with the optimal values of 0.89, 35.79 and 0.71 in 1.0 g N·seedling^-1 treatment. N contents in different organs of C. lanceolata clonal seedlings were in the order of leaf > root > stem. Compared with the CK, the N contents in root, stem and leaf increased by 39.6%, 16.6% and 41.1% in the conventional fertilization treatment, and by 22.6%-81.4%, 27.3%-152.6% and 73.6%-135.5% in exponential fertilization treatments. N contents in root, stem and leaf in the exponential fertilization treatments of 1.0 and 2.0 g N·seedling^-1 were significantly higher than those in the conventional fertilization treatment. P and K contents were not significantly different among the different organs. Considering the characteristics of seedling growth, chlorophyll fluorescence, the contents of N, P and K, the exponential fertilization treatment of 1.0g N· seedling^-1 was the best in cultivating C. lanceolata clonal seedlings in this experiment.

Changes in photosynthetic capacity during leaf senescence of Liquidambar formosana

LUO Zi-dong, GUAN Hua-de, ZHANG Xin-ping, LIU Na

2016, 27(10):  3129-3136.  doi:10.13287/j.1001-9332.201610.008

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In this study, the photosynthetic light response curves were measured for Liquidambar formosana during the leaf senescence from October to December in 2014. The measurements were simulated by a photosynthetic light response model (Ye model) and the conventional non-rectangular hyperbola model, in order to understand the photosynthetic capacity of senescing leaves of L. formosana. The results showed that the light sensitivity of the net photosynthetic rate decreased gra-dually during the leaf senescence. The measured maximum net photosynthetic rate was about 2.88 μmol CO₂·m^-2·s^-1 when the leaf color just turned yellow, and dropped to 0.95 μmol CO₂·m^-2·s^-1 in the later stage of leaf senescence (8th December). The two photosynthetic light-response models performed well in fitting the observation data, with Ye model being slightly better. Parameters estimated from the two models, such as the maximum net photosynthetic rate, the appa-rent quantum yield, the quantum yield at the light compensation point and the dark respiration rate, all gradually decreased with time, quantitatively describing the decrease in the photosynthetic capacity during the leaf senescence for L. formosana. The senescing leaves of L. formosana maintained positive net photosynthesis rates during the whole senescence, which had positive impact on carbon assimilation in the study area.

Effects of truncation intensity on the biomass allocation and physiological characteristics of Dendrocalamus latiflorus

TONG Long, LI Bin, CHEN Li-jie, ZHANG Wei, GENG Yang-hui, XIE Jin-zhong, WANG Ling

2016, 27(10):  3137-3144.  doi:10.13287/j.1001-9332.201610.038

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The effects of three different truncation treatments, i.e., light, medium and heavy truncation treatments on biomass allocation, current-year twig indexes, and quantity of commodity lea-ves, net photosynthetic rate (P_n), transpiration rate (T_r), water use efficiency (WUE), and leaf water potential (LWP) values of Dendrocalamus latiflorus were studied, and the adaptation mechanisms and survival strategy of D. latiflorus under these silvicultural truncation treatments were discussed. Results showed that the biomass of D. latiflorus and its allocation rates were significantly affected by truncation treatments, compared with the untruncated control. Leaf to branch, leaf to stem, and branch to stem biomass ratios under all truncation treatments were significantly higher than under the untruncated control. The diameter, number, and length of current-year twigs, and the quantity of commodity leaves in light truncation and medium truncation treatments were markedly higher than in the control, and were increased by 43.0%, 53.3%, 29.8% and 39.5%, respectively, in medium truncation treatment compared with the control. After truncation treatments, the overall trend of the physiological characteristics of D. latiflorus, including P_n, T_r, WUE, LWP values, were displayed in the order of the peak stage > the telophase stage > the initial stage. The P_n, T_r and WUE values of D. latiflorus were significantly improved in the truncation treatments. The P_n va-lues were greatest in the medium truncation treatment followed by the light truncation treatment, heavy truncation treatment, and were the lowest in the control at the peak and telophase stages. At the peak and telophase stage the P_n values in the medium truncation treatment were 1.4 and 1.3 times as much as the control. The T_r values at the initial, peak and telophase stages were the greatest in the heavy truncation treatment, followed by the middle truncation treatment and the light truncation treatment, and were the lowest in the control. In this study, the medium truncation treatment showed a significant advantage in improving plant biomass allocation, quantity of commodity leaves, and other physiological indices, and could effectively improve the ability of moisture acquisition for D. latiflorus.

Change of ion content in Phyllostachys vivax and Ph. glauca and its relationships with growth and photosynthesis in coastal regions

LI Juan, GAO Jian, SUN Zhong-yuan, LI Xue-ping, MU Shao-hua

2016, 27(10):  3145-3152.  doi:10.13287/j.1001-9332.201610.007

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The changes of Na⁺, K⁺, Ca²⁺, Mg²⁺contents of 10 year-old Phyllostachys vivax and Ph. glauca and the relationships with the growth and photosynthesis were investigated in the shelter belt of coastal beach with three salt levels, i.e., 0.1% of mild salinity zone, 0.2% of moderate salinity zone, and 0.4% of severe salinity zone. Compared with the mild salinity zone, bamboo density and diameter of Ph. vivax growing in the severe salinity zone decreased by 30.4% and 28.8%, and such reductions were 44.1% and 31.2% for Ph. glauca, respectively. Salinity decreased the biomass of the two species, and the decrease of biomass in shoots was greater than that in underground organs. Compared with the mild salinity zone, the net photosynthetic rate (P_n) and the maximum PSⅡ photochemical efficiency (F_v/F_m) of Ph. vivax and Ph. glauca decreased by 57.6% and 67.7%, and 6.1% and 7.4% in the severe salinity zone, respectively. Ph. vivax had stronger salt-tolerance than Ph. glauca in saline environment. Na⁺ contents in roots, rhizome, stems, and leaves were significantly elevated in Ph. vivax and Ph. glauca with increasing soil salinity, however, the contents of K⁺, Ca²⁺ and Mg²⁺ were reduced. Na⁺ was markedly accumulated in roots, and K⁺ was generally enriched in shoots. Salinity led to an evident decline of Ca²⁺ in Ph. vivax roots and Mg²⁺ in Ph. glauca leaves. The biomass, P_n and F_v/F_m of the two species were usually negatively correlated to Na⁺ content, and positively correlated to K⁺ and Ca²⁺ contents.

Response of distribution pattern and physiological characteristics of apple roots grown in the dry area of eastern Gansu to ground mulching

SUN Wen-tai, MA Ming, DONG Tie, LIU Xing-lu, ZHAO Ming-xin, YIN Xiao-ning, NIU Jun-qiang

2016, 27(10):  3153-3163.  doi:10.13287/j.1001-9332.201610.032

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The objective of the experiment is to ascertain the effects of different mulching materials on the distribution and physiological activity of apple roots as well as the soil physicochemical pro-perties in the rain-fed Longdong arid areas. With fourteen years old apple trees as test material, the different classes of roots were collected by using soil profile method and stratified sampling in soil profile to investigate the spatial distribution, root biomass, root length and surface area. The activity of root and antioxidant enzymes and some antioxidant indexes were measured. Soil bulk density and soil porosity in different soil layers were determined. The results indicated that ground covering treatment increased the soil moisture, porosity and organic matter content, and the amplification were 2.7%-11.6%, 3.2%-27.7%, 5.1%-36.0%, respectively compared with the control. The soil bulk density was reduced by 88.7%-96.4%. The roots of CK distributed mainly in soil layer of 0-60 cm in depth, 30-120 cm away from the trunk. However, with straw and plastic mulching the roots distributed mainly in the layer of 0-100 cm in depth, 0-150 cm and 0-60 cm away from the trunk, respectively, mostly concentrated in the 20-40 cm layer close to the ground. Plastic mul-ching made a narrower horizontal root distribution than CK and the total fine root amount was 96.4% of that of CK, and that in 0-60 cm layer accounted for 51.6% of the total fine root amount. More-over, the mulching resulted in a higher activity of root and antioxidant enzymes in 0-80 cm layer. The root activity with straw mulching was 111.3%-136.7% as much as the control. For sake of the efficacy on improving root distribution and physiological activity, the straw mulching was suggested as a better way for soil management in apple orchard in dry area of eastern Gansu.

Stem biomass estimation models for dominant shrubs on the northern Loess Plateau of China

YANG Xian-long, WEI Xiao-rong, SHAO Ming-an

2016, 27(10):  3164-3172.  doi:10.13287/j.1001-9332.201610.009

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A total of 200 stems of Caragana korshinskii and 210 stems of Salix psammophila were collected in the late August of 2015 in the Liudaogou catchment of Shenmu County, Shaanxi Pro-vince, China. Basal diameter (D), length (H), water content (W₀), fresh mass (W_F) and dry mass (W) were measured for each stem of the two species. Exponential and allometric equations were used to establish relationship models relating stem biomass to its morphological parameters. Altogether four models were established for each species, and their accuracy of estimation was also validated. The results showed that, the allometric model that used D²H as input variable was optimal in estimating stem biomass for C. korshinskii and S. psammophila, after transformed into its linear form. Meanwhile, the heteroscedasticity of the biomass data was greatly eliminated. This model had a maximum value of coefficient of determination (R²), and meanwhile minimum values of mean error (ME), mean absolute error (MAE), total relative error (TRE), mean systematic error (MSE), and mean absolute percentage error (MPSE), thus basically meeting the requirement of the accuracy in ecological study.

Biomass allocations and their response to environmental factors for grass species in an arid-hot valley

YAN Bang-guo, FAN Bo, HE Guang-xiong, SHI Liang-tao, PAN Zhi-xian, LI Jian-cha, YUE Xue-wen, LIU Gang-cai

2016, 27(10):  3173-3181.  doi:10.13287/j.1001-9332.201610.005

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The effects of water supply frequency, nutrient addition and clipping on biomass allocations among roots, stems and leaves as well as their allometric scaling relationships for six grass species from an arid-hot valley were investigated. The results showed that the fraction of leaf biomass significantly increased from 25.1% to 31.2% and the faction of stem biomass decreased from 43.7% to 34.2% under clipping treatment. Fertilization significantly decreased the faction of root biomass from 34.0% to 30.8%. Water treatments had no significant effect on biomass allocations. Species identity significantly affected biomass allocations among roots, stems and leaves. Species adapted to infertile soils allocated more biomass into leaves and roots and less into stems. There were significant interactions between species and environmental factors, suggesting that the effects of environmental factors on biomass allocations differed among species. Allometric constants and scaling exponents of leaf-stem for species adapted to infertile soils were greater than those for other species. Allometric constants and scaling exponents of stem-root for species adapted to infertile soils were lower than those for other species. In total, nutrient addition significantly increased allometric constants of leaf-stem and leaf-root while clipping significantly reduced scaling exponents of stem-root. The frequency of water supply had no significant effects on the allometric scaling relationships among different organs. The effects of environmental factors on the allometric scaling relationships between different organs differed among species. The differences in biomass allocations and their responses to environmental factors among different species might affect plant adaptations to environmental changes.

Effects of stem and leaf decomposition in typical herbs on soil enzyme activity and microbial diversity in the south Ningxia loess hilly region of Northwest China

LI Xin, LI Ya-yun, AN Shao-shan, ZENG Quan-chao

2016, 27(10):  3182-3188.  doi:10.13287/j.1001-9332.201610.016

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With the method of litter bags, the characteristics of soil enzyme activities, soil microbial diversity at later stage of decomposition, and the relationships between soil enzyme activity and initial soil property were investigated in the process of stem and leaf decomposition of three typical herbs, i.e., Stipa bungeana, Artemisia sacrorum and Thymus mongolicus in the south Ningxia loess hilly region, Northwest China. The results showed that soil enzyme activity increased under different treatments after 480 d during stem and leaf decomposition. Soil sucrose activity (32.40 mg·g^-1·24 h^-1) and alkaline phosphatase activity (1.99 mg·g^-1·24 h^-1) were the highest in S. bungeana treatment. Soil urease activity (2.66 mg·g^-1·24 h^-1) was the highest in T. mongolicus treatment, and soil cellulase activity (1.42 mg·g^-1·72 h^-1) was the highest in A. sacrorum treatment. Soil cellulose activity at later stage of decomposition had significant positive correlation with initial microbial biomass carbon of soil. Soil cellulose activity at later stage of decomposition had significant negative correlation with initial nitrate nitrogen content of soil. Ace index, Chao index and Shannon index of soil bacteria and fungi in plant tissue addition treatments were higher than in the control. However, Simpson index was opposed. The stem and leaf decomposition significantly promoted the abundance and diversity of soil bacteria and fungi, accelerated the decomposition rate of stems and leaves, and promoted the cycle and transformation of soil nutrients.

Changes in stoichiometry of soil carbon, nitrogen and phosphorus in the early stage of temperate forest succession in Maoershan, Northeast China

ZHANG Jia-hui, WANG Xing-chang, WANG Chuan-kuan

2016, 27(10):  3189-3195.  doi:10.13287/j.1001-9332.201610.003

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A soil displacement experiment was established in the Maoershan Forest Ecosystem Research Station in 2004, replacing the cropland soil of the 0-30 cm depth with the eluvial horizon soil (A treatment), the sediment horizon soil (B treatment) and the parent material horizon soil (weathered sand, C treatment) of an adjacent temperate broadleaved stand. The three treatments simulated the secondary successions from forest clear-cutting, bare soil without seed bank, and primary succession, respectively. Changes in soil carbon, nitrogen, phosphorus and their stoichiometry were examined in 2014. The results indicated that during the ten-year succession, the contents of soil C, N and P changed insignificantly in the A treatment. The contents of soil C and N decreased by 34.7% and 38.6% in the B treatment, but increased by 63.4% and 198.4% in the C treatment, respectively. The slope of the log-transformed N-C relationships decreased significantly during the succession, while the slope of the log-transformed P-N relationships increased significantly. After 10-year’s succession, only the C:N decreased by 44.5%, and the N:P increased by 283.6% in the C treatment, with no significant changes for others. The contents of C, N and P were significantly correlated with the root biomass and necromass, suggesting that the succession might change the soil elements and their stoichiometric relationships through modifying organic matter inputs.

O₃ dry deposition flux observation and soil resistance modeling over a bare soil in Nanjing area in autumn

HUANG Ji-qing, ZHENG You-fei, XU Jing-xin, ZHAO Hui, YUAN Yue, CHU Zhong-fang

2016, 27(10):  3196-3204.  doi:10.13287/j.1001-9332.201610.001

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In this study, the concentration of O₃ and its deposition flux over a bare soil in Nanjing in autumn were observed by using an eddy covariance system with rapid ozone analyzer. We analyzed the correlation of ozone concentration, deposition flux, and meteorological conditions in order to explore the characteristics of the variations in ozone deposition flux and deposition velocity. We also compared flux and velocity by using modeled soil resistance with observations. The results showed that the diurnal variation of ozone concentration exhibited a single peak distribution, and it increased due to radiation enhancement from September 25th to October 28th, 2015. Ozone deposition flux over a bare soil in autumn was mainly affected by its concentration, with diurnal average values varying from -31.4 to -156.8 ng·s^-1·m^-2(the negative sign indicated that the deposition direction was toward the ground). As a result of non-vegetation over a bare soil, the ozone deposition flux was significantly influenced by environmental factors. Diurnal average of deposition velocities varied in the range of 0.09-0.30 cm·s^-1. The turbulence exchange played a major role in the atmosphere transportation of ozone, and underlying surface condition was particularly important to O₃ dry deposition over the bare soil. Soil resistance (R_s) increased exponentially with air relative humidity (RH), and the equation was R_s=89.981e^0.0246RH. The parameterized ozone deposition velocities and fluxes were in good agreement with the measured values.

Inorganic nitrogen wet deposition in eastern China: Comparison of different land use-based monitoring sites in north and south regions

YANG Dao-wei, XU wen, TANG Ao-han, LU Li, LIU Xue-jun

2016, 27(10):  3205-3212.  doi:10.13287/j.1001-9332.201610.012

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China is one of the global hotspots of atmospheric nitrogen (N) deposition. This is especially true for eastern China, an economically developed and densely populated area, which emits large quantities of anthropogenic reactive N species to the air and experiences high levels of atmospheric N deposition. Few studies, however, have examined spatial variations of N deposition across different ecosystems in northern and southern regions of eastern China. Using the traditional rain gauge (SDM6A) method, we conducted a three-year (2011-2013) study to quantify wet N deposition fluxes at twelve sites (six northern and six southern monitoring sites, covering urban, rural and background land use types) in China. The annual volume-weighted mean (VWM) concentrations of NH₄⁺-N, NO₃^--N and total inorganic N (TIN) atmonitoring sites were in the ranges of 0.62-2.76, 0.54-2.50 and 1.25-4.92 mg N·L^-1, and averaged 1.4, 1.5 and 2.9 mg N·L^-1, respectively. Northern sites showed higher concentrations of N species in precipitation than southern sites. Annual deposition fluxes of NH₄⁺-N, NO₃^--N and TIN were in the ranges of 7.0-18.3, 6.9-18.9 and 14.9-32.6 kg N·hm^-2·a^-1, averaging 11.5, 12.2 and 23.7 kg N·hm^-2·a^-1, respectively. There were significant differences in total N deposition fluxes among different land use types in the north, showing the decreasing order of urban sites (26.3±6.4 kg N·hm^-2·a^-1)> rural sites (21.8±3.5 kg N·hm^-2·a^-1)> background (15.5±1.3 kg N·hm^-2·a^-1). Total N deposition fluxes at urban, rural and background sites in the south were (26.8±2.7), (25.5±2.9) and (20.5±2.4) kg N·hm^-2·a^-1, respectively, showing no significant spatial variation. While urban sites did not show obvious regional differences, total N wet deposition fluxes at rural and background sites in the south were significantly higher than those at corresponding sites in the north. Our results revealed that both south and north regions of eastern China (including background areas) are receiving high levels of wet N deposition and associated ecological and environmental risks should be considered.

Response of biocrust-soil system respiration to winter low temperature and simulated warming

GUAN Chao, ZHANG Peng, CHEN Yong-le, SONG Guang, ZHOU Yuan-yuan, LI Xin-rong

2016, 27(10):  3213-3220.  doi:10.13287/j.1001-9332.201610.002

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To study the effects of low temperature and simulated warming on respiration of biocrust-soil systems, intact soil columns covered by two dominant types of biocrusts (moss and algae-lichen crusts), were collected in a natural vegetation area in the southeast fringe of the Tengger Desert. Automated soil respiration system (Li-8150) was used to measure respiration rates in biocrust-soil systems under warming (by placing them in an open top chamber) and non-warming treatments in winter (from November 2015 to January 2016). During the whole observation period, soil respiration rates covered by moss crusts were significantly higher than those covered by algae-lichen crusts, which were -0.052 to 0.418 and -0.032 to 0.493 μmol·m^-2·s^-1, respectively. The respiration rates of the two types of biocrust-soil systems showed significant positive linear correlations with soil temperature and volumetric soil water content at 5 cm depth. Through speeding-up the evaporation rates of soil moisture, imitated warming in winter impeded respiration rates of the two biocrust-soil systems. During the whole observation period, the cumulative carbon (C) release by moss crust-soil system (9.90 g C·m^-2) was dramatically higher than that of algae-lichen crust-soil system (7.00 g C·m^-2). The cumulative C release by the biocrust-soil systems in this region in winter was 7.40 g C·m^-2, thus comprising an important part of annual C budget in the desert ecosystems.

Risk assessment of cadmium in rice in Xiangtan, Hunan, China based on Bayesian method

XU Jing-jing, WU Bo, ZHANG Ling-yan, GUO Shu-hai, LI Gang, LI Feng-mei

2016, 27(10):  3221-3227.  doi:10.13287/j.1001-9332.201610.020

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In this study, a total of 73 groups of paddy soil and rice samples were collected from 3 counties of Xiangtan City, Hunan Province, which were Xiangtan, Yuhu, and Xiangxiang, respectively. The total content of Cd in soil and rice samples was determined, the available Cd in soil samples also was measured, and the correlation analysis was conducted among them, respectively. According to the prior probability and data feature, we proposed to use the Bayesian method to eva-luate the risk of Cd content exceeding criterion in rice and construct the risk assessment model. The results indicated that, the average soil Cd content, soil available Cd content and the rice Cd content in the study area were (0.891±0.638) mg·kg^-1, (0.791±0.582) mg·kg^-1 and (0.376±0.395) mg·kg^-1, respectively, and the exceeding standard rate of Cd content in soil and rice reached 89.0% and 52.1%. The rice Cd content was significantly correlated with the available Cd content and total Cd content in soil in Xiangtan and Yuhu. A better correlation was presented between the soil available Cd content and rice Cd content. The rice Cd content in Xiangxiang had no correlation with total Cd content and available Cd content in soil. When the total Cd content and available Cd content were selected as the variables of Bayesian model, the deviations between the predicted exceeding probability of Cd in rice and the true exceeding standard rate were 6.6% and 3.9%, respectively, which proved the Bayesian risk assessment model was reliable. Selecting the available Cd content as the model variable, the predicted result was closer to the true value.

Effects of nitrogen application rate on potassium uptake and utilization of direct-seeded cotton after wheat harvest

ZHANG Guo-wei, YANG Chang-qin, LIU Rui-xian, ZHANG Lei, NI Wan-chao

2016, 27(10):  3228-3236.  doi:10.13287/j.1001-9332.201610.029

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By using cotton cultivar CCRI-50 as material, field experiments were conducted in the summer seasons of 2013 and 2014 at the experimental station of Jiangsu Academy of Agricultural Sciences (Nanjing, China) to study the effects of different nitrogen application rates (0, 60, 120, 150, 180 and 240 kg N·hm^-2) on the potassium uptake and utilization of the cotton plant that was direct-seeded after wheat harvest. Data suggested that the elevated nitrogen application rates increased the cotton potassium uptake of all growth stages, and the largest increment was observed at the peak flowering-boll opening stage. Nitrogen application also changed the uptake percentage of potassium uptake of each stage, i.e., the percentage of potassium uptake decreased in the stage from seedling to peak flowering, while increased in the stage from peak flowering to boll maturing. In addition, the elevated nitrogen applications reduced the decreasing rate of nitrogen concentration in upper fruiting branches, but promoted the decreasing rate in middle and low fruiting branches at later growth stages. As the nitrogen application rate increased, the marginal effect of potassium uptake (promoted amount of potassium uptake due to 1 kg increase of N application) increased first and then decreased, and the lint production efficiency of potassium descended steadily. In cotton plants that were direct-seeded after wheat harvest, potassium and biomass were mainly accumulated in the lower and middle fruiting branches. At the 150 and 180 kg N·hm^-2 application levels, much more potassium was allocated to the reproductive organs and the characters and the eigenvalues of simulated curves of potassium concentration and total potassium accumulation were more optimized than those at the higher or the lower N application levels. At the high nitrogen application (more than 180 kg N·hm^-2) level, the marginal effect of potassium uptake and lint production efficiency decreased, and at the lower nitrogen application (less than 150 kg N·hm^-2) level, lint yield was lower due to the decrease of economic coefficient of biomass and potassium in the middle and low fruiting branches.

Effects of shading and plant density on ear development and plant productivity of spring maize in Northeast China

CHEN Tao, SONG Zhen-wei, ZHANG Ming, YAN Xiao-gong, ZHU Ping, REN Jun, DENG Ai-xing, ZHANG Wei-jian

2016, 27(10):  3237-3246.  doi:10.13287/j.1001-9332.201610.028

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It is important to investigate the effects of shading on maize ear characteristics and yield, which can provide references to variety breeding and agronomic technique improvement for coping with climate change and dense planting. An experiment was carried out with two varieties (compact type hybrid ZD909, flat type hybrid ND4) and two planting densities (45000 and 90000 plants·hm^-2) at Gongzhuling City, Jilin Province. Two treatments were conducted for each variety and planting density, including shading (with a shading degree of 65% from small bell mouth stage to mature stage) and no shading treatment (CK). The results showed that shading affected maize ear development significantly. Shading delayed maize anthesis and silking stages, especially prolonging the length of anthesis-silking interval by 3-15 days compared with the CK. Moreover, shading decreased dry matter accumulation of spring maize significantly, leading to more than 50% (50.8%-87.0%) of reduction in grain yield. The negative effects of shading on ear characteristics and yield of spring maize with dense planting was greater than that with sparse planting. The variety with a dense plant type achieved fewer effects on ear characteristics and grain yield than the variety with a sparse plant type under shading and dense planting. The variety with a dense plant type had strong adaptability to ecological environment change and the consistency in density-tolerance and shade-tolerance.

Effects of N application reduction and fertilizing distance on saving fertilizer and improving yield in maize/soybean intercropping system

CHEN Ping, DU Qing, ZHOU Li, YANG Huan, DONG Qian, SONG Chun, YANG Wen-yu, YONG Tai-wen

2016, 27(10):  3247-3256.  doi:10.13287/j.1001-9332.201610.031

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To study the effect of N supplied levels and fertilization distances on saving fertilizer and improving yield in maize/soybean intercropping system, a field experiment was carried out with three N supplying levels ( RN₁: 210 kg N·hm^-2, RN₂: 270 kg N·hm^-2 and CN: 330 kg N·hm^-2) and four fertilizing distances (D₁: 0 cm, D₂: 15 cm, D₃: 30 cm and D₄: 45 cm, indicating the distance between fertilizing site and maize in narrow row). Compared with CN, the results showed that dry matter accumulation and translocation, and their contribution to grain of post-anthesis maize under RN₂ were increased by 1.4%, 23.0% and 16.0%, respectively. Meanwhile, kernel number per ear and grain yield per plant of maize were increased by 1.6% and 4.9%. For soybean, dry matter accumulation and translocation, and their contribution to grain at pre-anthesis under RN₂ were increased by 2.1%, 37.9% and 26.9%, respectively. Both of soybean grain number and yield per plant were increased by 7.3%. For the maize-soybean intercropping system, N uptake and use efficiency of RN₂ were 5.0% and 44.4% higher than those of CN. The soil N content of maize was raised by 4.1% under RN₂, but decreased by 0.8% for soybean. The saving fertilizer and improving yield effect of D₂ were the best among all the fertilizing distances. Under RN₂, contribution rate of dry matter accumulation to grain after anthesis and kernel number per ear of maize in D₂ were 57.2% and 9.4% higher than those of D₁. Compared with D₄, the contribution rate of dry matter accumulation to grain before anthesis and grain number per plant of soybean in D₂ were increased by 335.2% and 2.4%, respectively. For the maize/soybean intercropping system, N uptake and use efficiency of D₂ were 15.1% and 112.4% greater than those of D₁, and 21.4% and 66.3% higher than those of D₄. The total soil N content of maize in D₂ was 6.6% higher than that of D₁, and the index for soybean was 16.0% higher than that of D₄. Appropriate N application reduction and fertilizing distance would be beneficial to transfer dry matter to grain, improve grain number per plant, 100-grain mass and yield, promote N uptake and increase fertilizer use efficiency in the intercropping system, which could achieve the purpose of saving fertilizer and improving yield.

Effects of nitrogen fertilization on the nitrogen uptake, accumulation, and seed quality of oil peony

JIANG Tian-hua, SHAN Pei-pei, HUANG Zai-fan, WEN Li-zhu, SUN Cui-hui, LIU Kun, ZHENG Cheng-shu

2016, 27(10):  3257-3263.  doi:10.13287/j.1001-9332.201610.006

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Field experiments, including four levels of N application 0, 18, 24, 30 g N·m^-2, were carried out to clarify the effects of nitrogen fertilization on N accumulation and translocation in lea-ves as well as the seed quality of oil peony (Paeonia ostii ‘Fengdan Group’). The results showed that the nitrogen application significantly increased the height, canopy, flower diameter and flower dry mass. The heights under the treatments 24 and 30 g N·m^-2 increased by 14.7% and 15.2% compared with CK, respectively. Moreover, the nitrogen application improved seed yield. The highest seed yields were acquired under the treatments 24 and 30 g N·m^-2, which were 15.2% and 15.4% higher than that of CK, respectively. The N accumulation and translocation in leaves and the N accumulation in seeds all increased with the nitrogen application level. The greatest leaf contribution proportion was acquired under the treatment 24 g N·m^-2. The nitrogen application significantly increased the contents of protein N, total amino acid, and some saturated and unsaturated fatty acids in seeds. In this experiment, the N input of 24 g N·m^-2 was optimal to obtain the higher N translocation amount, N translocation efficiency and N contribution proportion from leaves to seeds, seed yield as well as the contents of protein N, amino acid and unsaturated fatty acids.

Characteristics of soil aggregates and inorganic phosphorus fractions in soils returned from cropland to tea

WU Wen, ZHENG Zi-cheng, LI Ting-xuan, LIU Tao

2016, 27(10):  3264-3272.  doi:10.13287/j.1001-9332.201610.030

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With soils returned from cropland to tea planting for different ages (2-3, 9-10 and 16-17 years old) as the object, and the nearby cropland soil as the control in Zhongfeng Township, Mingshan County, Ya’an, Sichuan Province, field investigation and laboratory analysis were combined to investigate the characteristics of soil aggregates and inorganic phosphorus fractions in response to the returning from cropland to tea. The particle size of >2 mm was the dominant aggregate size for the cropland and tea soils. With the increasing age, soil aggregate content of >5 mm particle size increased, while that of <5 mm particle size decreased gradually. In the earlier ages, for the mean mass diameter (MWD) and the geometry mass diameter (GWD), there was no significant difference between the cropland and tea soils. The MWD and GMD for the tea soils of 9-10 years and 16-17 years increased with the increasing age and were higher than those of the control. Compared with the cropland, the tea soils showed higher contents of Al-P and Fe-P, and lower content of O-P. The content of O-P in different particle size of aggregates reduced with the increasing age, while that of Al-P and Fe-P increased with the increasing age. The contents of Al-P and Ca-P in the cropland and tea soils increased with the decrease of the particle size and reached the maximum value in the particle size of <0.25 mm. The highest content of Fe-P was observed in the particle size of <0.25 mm, followed by 2-5 mm and 0.25-0.5 mm. Besides, with the returning fromcropland to tea planting, O-P gradually accumulated in smaller particle size and possessed higher content in the particle size of <2 mm.

Spatial differentiation and impact factors of Yutian Oasis’s soil surface salt based on GWR model

YUAN Yu-yun, WAHAP Halik, GUAN Jing-yun, LU Long-hui, ZHANG Qin-qin

2016, 27(10):  3273-3282.  doi:10.13287/j.1001-9332.201610.022

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In this paper, topsoil salinity data gathered from 24 sampling sites in the Yutian Oasis were used, nine different kinds of environmental variables closely related to soil salinity were selec-ted as influencing factors, then, the spatial distribution characteristics of topsoil salinity and spatial heterogeneity of influencing factors were analyzed by combining the spatial autocorrelation with traditional regression analysis and geographically weighted regression model. Results showed that the topsoil salinity in Yutian Oasis was not of random distribution but had strong spatial dependence, and the spatial autocorrelation index for topsoil salinity was 0.479. Groundwater salinity, groundwater depth, elevation and temperature were the main factors influencing topsoil salt accumulation in arid land oases and they were spatially heterogeneous. The nine selected environmental variables except soil pH had significant influences on topsoil salinity with spatial disparity. GWR model was superior to the OLS model on interpretation and estimation of spatial non-stationary data, also had a remarkable advantage in visualization of modeling parameters.

Agricultural soil contamination from As and Cd and its responses to landscape heterogeneity at multiple scales in Guangzhou, China

XU Hui-qiu, HUANG Yin-hua, WU Zhi-feng, CHENG Jiong, LI Cheng

2016, 27(10):  3283-3289.  doi:10.13287/j.1001-9332.201610.021

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Based on 641 agricultural top soil samples (0-20 cm) and land use map in 2005 of Guangzhou, we used single-factor pollution indices and Pearson/Spearman correlation and partial redundancy analyses and quantified the soil contamination with As and Cd and their relationships with landscape heterogeneity at three grid scales of 2 km×2 km, 5 km×5 km, and 10 km×10 km as well as the determinant landscape heterogeneity factors at a certain grid scale. 5.3% and 7.2% of soil samples were contaminated with As and Cd, respectively. At the three scales, the agricultural soil As and Cd contamination were generally significantly correlated with parent materials’ composition, river/road density and landscape patterns of several land use types, indicating the parent materials, sewage irrigation and human activities (e.g., industrial and traffic activities, and the additions of pesticides and fertilizers) were possibly the main input pathways of trace metals. Three subsets of landscape heterogeneity variables (i.e., parent materials, distance-density variables, and landscape patterns) could explain 12.7%-42.9% of the variation of soil contamination with As and Cd, of which the explanatory power increased with the grid scale and the determinant factors varied with scales. Parent materials had higher contribution to the variations of soil contamination at the 2 and 10 km grid scales, while the contributions of landscape patterns and distance-density variables generally increased with the grid scale. Adjusting the distribution of cropland and optimizing the landscape pattern of land use types are important ways to reduce soil contamination at local scales, which urban planners and decision makers should pay more attention to.

Spatial-temporal pattern and factor diagnoses of agroecosystem health in major grain producing areas of Northeast China: A case study in Jilin Province

ZHAO Hong-bo, ZHENG Hui, MIAO Chang-hong, SHAO Tian-tian, FENG Yuan-bo

2016, 27(10):  3290-3298.  doi:10.13287/j.1001-9332.201610.033

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It is of great significance to study agroecosystem health in major grain producing areas based on the theory and method of ecosystem health. This paper selected Jilin Province as the study area, and an evaluation index system of agroecosystem health was built based on the SSI-VOR conceptual framework model. Using the optimal combined weights method, comprehensive evaluation assessment, GIS spatial analysis and grey slope similarity incidence models, the spatial-temporal pattern of agroecosystem health and influence factors were analyzed from 2000 to 2011 in Jilin Pro-vince. The results indicated that, temporally, the composite index of agroecosystem health showed a rising trend in Jilin Province from 1995 to 2011, and the agroecosystem health level changed from not healthy to relatively healthy; spatially, the spatial discrepancy of agroecosystem health level tended to become larger, which remained unchanged in central area, while was gradually improved in southeast and west. The main contributors which improved the agroecosystem health level were economic driving force, environmental management and social development, while the main ‘dragging’ factors were ecological pressure, organization structure and input capacity. Finally, relevant measures were put forward to improve the agroecosystem health condition.

Spatio-temporal characteristics of agricultural drought in Shaanxi Province, China based on integrated disaster risk index

HE Bin, WANG Quan-jiu, WU Di, ZHOU Bei-bei

2016, 27(10):  3299-3306.  doi:10.13287/j.1001-9332.201610.040

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With the change of climate, agricultural drought has directly threatened the food security. Based on the natural disaster risk theory, we analyzed the spatial and temporal characteristics of agricultural drought in Shanxi Province from 2009 to 2013. Four risk factors (hazard, exposure, vulnerability, and drought resistance ability) were selected with the consideration of influence factors of drought disasters. Subsequently, the index weight was determined by the analytic hierarchy process (AHP) and the aggregative indicator of natural disaster risk was established. The results showed that during the study period, the agricultural drought risk slightly declined in the northern Shaanxi, but increased sharply in the southern Shaanxi, especially in Shangluo City. While for the central part of Shaanxi Province, it maintained good stability, which was the highest in Xianyang City and the lowest in Xi’an City. Generally, the agricultural drought risk in Shaanxi Province gradually increased from south to north.

Carbon footprints of major staple grain crops production in three provinces of Northeast China during 2004-2013.

HUANG Xiao-min, CHEN Chang-qing, CHEN Ming-zhou, SONG Zhen-wei, DENG Ai-xing, ZHANG Jun, ZHENG Cheng-yan, ZHANG Wei-jian

2016, 27(10):  3307-3315.  doi:10.13287/j.1001-9332.201610.036

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Northeast China is one of the most important farming regions in China, due to its great contribution to national food security. Crop production is a main source of carbon emission. To assess the differences in carbon footprints of major grain crop production will benefit the achievement of low carbon agriculture. Therefore, this study calculated the regional carbon foot prints of rice (Oryza sativa), maize (Zea mays) and soybean (Glycine max) production in Northeast China du-ring 2004-2013 using the provincial statistical data, including crop yield, sown area and production inputs. The results showed that the highest area-scale carbon footprint was found in rice production, with the average value of (2463±56) kg CE·hm^-2, while the second was found in maize production during 2004-2013. The sharpest rise occurred in maize production, from 1164 kg CE·hm^-2 in 2004 to 1768 kg CE·hm^-2 in 2013, with the average rate of 67 kg CE·hm^-2·a^-1. The application of chemical fertilizer contributed to the carbon footprint largely, accounting for 45%, 90% and 83% for rice, maize and soybean, respectively. Moreover, the contribution of electricity for irrigation in rice production ranged from 29% to 42%, which was larger than that in maize and soybean production. The carbon footprints were significantly different among the three provinces of Northeast China. The highest yield-scaled carbon footprints for three crops were found in Jilin Province, while the lowest area-scaled carbon footprints found in Heilongjiang Province. Given to the large transfer of rural labor from agricultural to non-agricultural sections and the development of mechanization, diesel and other mechanical inputs would increase rapidly in the future. Therefore, improving ferti-lizer utilization, mechanical and irrigation efficiencies in crop production would be the main approaches to promoting low-carbon agriculture in Northeast China.

Dynamic evolution of wetland landscape spatial pattern in Nansi Lake, China

CHEN Zhi-cong, XIE Xiao-ping, BAI Mao-wei

2016, 27(10):  3316-3324.  doi:10.13287/j.1001-9332.201610.039

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Based on Landsat images in 1987, 2002 and 2014 from Nansi Lake located in Shandong Province, landscape pattern index, dynamic index, landscape gradient and gridding model were used for analysis of the wetland distribution in the lake. The results showed that the landscape contagion index and aggregation index gradually decreased from 1987 to 2014, while the landscape diversity index and evenness index gradually increased. The distribution of landscape area was more uniform while its patterns trended to be fragmented. Human activities impacted Nansi wetland distribution and the disturbance presented an increasing trend. The total area of Nansi wetland gradually increased during the study period. The area of lake first decreased then increased, and the area reached the maximum in 2014. The area of the ponds along the riparian zone had increased gradually, but the increasing speed slowed down. The area of the rivers remained stable, while the area of the swamps decreased continually during the period. The change of landscape pattern of Nansi Lake wetland mainly resulted from agricultural activities, establishment of Nansi Lake Natural Reserve, and the South-to-North Water Diversion Project.

Regulation framework of watershed landscape pattern for non-point source pollution control based on ‘source-sink’ theory: A case study in the watershed of Maluan Bay, Xiamen City, China

HUANG Ning, WANG Hong-ying, LIN Tao, LIU Qi-ming, HUANG Yun-feng, LI Jian-xiong

2016, 27(10):  3325-3334.  doi:10.13287/j.1001-9332.201610.013

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Watershed landscape pattern regulation and optimization based on ‘source-sink’ theory for non-point source pollution control is a cost-effective measure and still in the exploratory stage. Taking whole watershed as the research object, on the basis of landscape ecology, related theories and existing research results, a regulation framework of watershed landscape pattern for non-point source pollution control was developed at two levels based on ‘source-sink’ theory in this study: 1) at watershed level: reasonable basic combination and spatial pattern of ‘source-sink’ landscape was analyzed, and then holistic regulation and optimization method of landscape pattern was constructed; 2) at landscape patch level: key ‘source’ landscape was taken as the focus of regulation and optimization. Firstly, four identification criteria of key ‘source’ landscape including landscape pollutant loading per unit area, landscape slope, long and narrow transfer ‘source’ landscape, pollutant loading per unit length of ‘source’ landscape along the riverbank were developed. Secondly, nine types of regulation and optimization methods for different key ‘source’ landscape in rural and urban areas were established, according to three regulation and optimization rules including ‘sink’ landscape inlay, banding ‘sink’ landscape supplement, pollutants capacity of original ‘sink’ landscape enhancement. Finally, the regulation framework was applied for the watershed of Maluan Bay in Xiamen City. Holistic regulation and optimization mode of watershed landscape pattern of Maluan Bay and key ‘source’ landscape regulation and optimization measures for the three zones were made, based on GIS technology, remote sensing images and DEM model.

Spatio-temporal characteristics of coupling coordination between the quality of population urbanization and land urbanization: The case of 12 central cities in Gansu Province, China

WANG Luo-jia, DONG Xiao-feng, LIU Xing-guang

2016, 27(10):  3335-3343.  doi:10.13287/j.1001-9332.201610.024

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According to the theory of system science, the paper took 12 central cities in Gansu Province as an example, and respectively built the quality assessment index system of population urbanization and land urbanization on the basis of scientific definition of the quality of population urbanization and land urbanization. Then the coupled coordination model was introduced to calculate the comprehensive development index and coupling coordination degree between quality of population urbanization and land urbanization by the dimension of time and space during 2005-2013. The results showed that population urbanization and land urbanization could only represent the speed of urbanization, it could not measure the quality of urbanization. Single index could only represent the urbanization development level in the narrow sense. Observed in time sequence, the quality and coupling coordination level of land and population urbanization in Gansu Province showed an overall rising trend. In general, the poorly intensive utilization of land resources was still the key factor restricting the quality of urbanization in Gansu Province. From the point of spatial pattern, in 2013, the quality of land urbanization lagged behind the quality of population urbanization to varying degrees in 11 central cities except Lanzhou, which belonged to the population urbanization lagging type. The urbanization quality of 12 central cities in Gansu Province was at an overall low coordinating stage.

Identification of ecological corridors and its importance by integrating circuit theory

SONG Li-li, QIN Ming-zhou

2016, 27(10):  3344-3352.  doi:10.13287/j.1001-9332.201610.035

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Landscape connectivity is considered as an extraordinarily important factor affecting various ecological processes. The least cost path (LCP) on the basis of minimum cumulative resis-tance model (MCRM) may provide a more efficient approach to identify functional connectivity in heterogeneous landscapes, and is already adopted by the research of landscape functional connecti-vity assessment and ecological corridor simulation. Connectivity model on circuit theory (CMCT) replaced the edges in the graph theory with resistors, cost distance with resistance distance to measure the functional connectivity in heterogeneous landscapes. By means of Linkage Mapper tool and Circuitscape software, the simulated landscape generated from SIMMAP 2.0 software was viewed as the study object in this article, aimed at exploring how to integrate MCRM with CMCT to identify ecological corridors and relative importance of landscape factors. The results showed that two models had their individual advantages and mutual complement. MCRM could effectively identify least cost corridors among habitats. CMCT could effectively identify important landscape factor and pinch point, which had important influence on landscape connectivity. We also found that the position of pinch point was not affected by corridor width, which had obvious advantage in the research of identifying the importance of corridors. The integrated method could provide certain scientific basis for regional ecological protection planning and ecological corridor design.

Purification efficiency of four different ecotypes of wetland plants on eutrophic water body

ZHOU Yue, HAN Yu-guo, ZHANG Meng, LI Dong-jie, WANG Cheng-zhi, ZHAO Yun, LIN Peng, YANG Lin-lin

2016, 27(10):  3353-3360.  doi:10.13287/j.1001-9332.201610.019

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Four wetland plant species (Acorus calamus, Typha orientalis, Lemna minor, Ceratophyllum demersum) were grown to compare the purification efficiency of wetland plant species alone and in combination on two eutrophic water bodies, high concentration sewage (influent) and low concentration sewage (effluent) in a wastewater treatment plant. The results showed that the concentration of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) decreased sharply at the beginning of the test, but this decreasing trend slowed down in the late phase. The wetland plants could remove TN, TP and COD from wastewater effectively, but the degree of purification was different among different wetland plant species and among different combinations of these species. The wetland plant species were more effective in reducing TN when used in combination than used alone, and the combination of T. orientalis, L. minor and C. demersum had the highest efficiency in removing TN. The emerged plant species alone were more effective in removing TP in the high concentration sewage, but wetland plant combinations had a higher removal efficiency of TP in the low concentration sewage. In the high concentration sewage, the COD removal efficiency of wetland plants was 85.1%-96.0%, and A. calamus and T. orientalis had the highest removal efficiency. In the low concentration sewage, the COD removal efficiency of wetland plants was 76.9%-94.8%, and the highest removal efficiency was observed in the combination of A. calamus, L. minor and C. demersum. On the whole, the efficiency of wetland plants in removing TN, TP and COD was significantly greater in the high concentration sewage than in the low concentration sewage, and pH was improved in both treatments.

Variations of soil microbial community composition and enzyme activities with different salinities on Yuyao coast, Zhejiang, China

SUN Hui, ZHANG Jian-feng, XU Hua-sen, CHEN Guang-cai, WANG Li-ping

2016, 27(10):  3361-3370.  doi:10.13287/j.1001-9332.201610.034

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In October 2015, soil samples with different salinity were collected in a coast area in Yuyao, Zhejiang, and soil microbial community composition, soil catalase, urease activities, as well as soil physical and chemical properties were studied. The results showed that Nitrospira took absolute advantage in the bacterial community, and showed good correlations to total potassium. Cladosporium and Fusarium were predominant in the fungal community. Meanwhile, Cladosporium was related to soil urease and total nitrogen, and same correlation was found between Fusarium and soil urease. Catalase activity ranged from 3.52 to 4.56 mL·g^-1, 3.08 to 4.61 mL·g^-1 and 5.81 to 6.91 mL·g^-1 for soils with heavy, medium and weak salinity, respectively. Catalase activity increased with the soil layer deepening, which was directly related to soil total potassium, and indirectly related to pH, organic matter, total nitrogen and total phosphorus through total potassium. Soil urease activity ranged among 0.04 to 0.52 mg·g^-1, 0.08 to 1.07 mg·g^-1 and 0.27 to 8.21 mg·g^-1 for each saline soil, respectively. Urease activity decreased with soil layer deepening which was directly related to soil total nitrogen, and was indirectly related to pH, organic matter and total potassium through total nitrogen. The total phosphorus was the largest effect factor on the bacterial community CCA ordination, and the urease was on fungal community.

Identification and degradation characteristics of a napropamide-degrading bacterium strain

ZHANG Cheng, WU Xiao-mao, LONG You-hua, LI Ming, LI Rong-yu, YIN Xian-hui

2016, 27(10):  3371-3378.  doi:10.13287/j.1001-9332.201610.017

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In order to investigate the microbial degradation mechanism of amide herbicide napropamide and its degradation bioaugmentation in soil, a bacterial strain LGY06 capable of utilizing napropamide as sole carbon and energy source was isolated from a tobacco-planted soil after successive application of napropamide. LGY06 was identified as Bacillus cereus based on morphological, physiological and biochemical characteristics, and the 16S rDNA homologue sequence analysis. The degradation of napropamide in pure cultures by LGY06 was fitted to the first-order function. The strain LGY06 could degrade more than 75.7% of 50 mg·L^-1 napropamide within 7 d. The optimal temperature and pH for napropamide degradation was 35 ℃ and 8.0, respectively. The pathway of napropamide degradation was elucidated based on metabolites identification by GC-MS. The main degradation products of napropamide by LGY06 were α-naphthol and propylacetanilide. The meta-bolism of napropamide by strain LGY06 involved dealkylation and oxidation (or hydrolyzation). Under the laboratory control conditions, the bacterial strain LGY06 could effectively enhance the degradation of napropamide in soil. Compared with the un-inoculated controls, the half-life of napropamide in sterilized soil, non-rhizosphere soil, and rhizosphere soil inoculated with the strain LGY06 was shorted by 79.5%, 36.6% and 41.1%, respectively.

Screening, identification and biocontrol effect of antagonistic actinomycetes against the pathogen of Cytospora sp. for apple tree

XUE Ying-yu, FAN Wan-ze, ZHANG Shu-wu, XU Bing-liang

2016, 27(10):  3379-3386.  doi:10.13287/j.1001-9332.201610.010

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The pathogen of Cytospora sp. was considered as the target fungus to evaluate the bio-control potential of antagonistic actinomycetes against Cytospora sp. in the present study, which was isolated from the rhizosphere soil of apple tree. Moreover, the antagonistic effect of actinomycetes against Cytospora sp. growth was determined by the method of confrontation and growth rate, and the screened antagonistic strain was identified by the method of morphology and molecular biology. Also, the inhibitory activity of strain ZZ-9 against the conidium germination and mycelia growth of Cytospora sp. was determined in vivo, and its bio-control effect on Cytospora sp. growth was determined in detached apple twigs. The results showed that fifteen strains of actinomycetes had the inhibitory effect on Cytospora sp. growth, among all the isolated strains, which accounted for 18.8% and especially the inhibitory rate of eight strains was more than 50%. In addition, among all the screened strains, the strain ZZ-9 presented the highest inhibitory rate of 96.4%, which was significantly higher than those of the other isolated strains. The strain ZZ-9 was initially identified as Streptomyces rochei according to cultural characteristics, physiological and biochemical properties and 16S rDNA analysis. The nucleotide sequences in GenBank accession number was registered as KT986228. Different dilution of ZZ-9 fermentation had significant inhibitory effect on Cytospora sp. conidium germination and mycelia growth. The inhibitory rates of the 50 times fermentation on both conidium germination and mycelia growth were more than 80%. The inhibited mycelia’s color was deepened, the mycelia branches were increased, and the ends of hyphae were swelled and deformed, even the protoplasm was concentrated and released. The bio-control effect of the ZZ-9 stock solution on Cytospora sp. growth was more than 75% in detached apple twigs. Thus, our results indicated that the strain ZZ-9 could be used for controlling apple tree Valsa canker in vivo and vitro.

Objective influencing factors of urban park accessibility

YIN Hong-yan, LI Jun-ying, SHI Tuo, ZHAO Dong, YANG Jing-hui, LI Jin-xin

2016, 27(10):  3387-3393.  doi:10.13287/j.1001-9332.201610.014

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Urban park accessibility is an important indicator to measure the level of urban modern development, and the harmonious relationships between people and land. It is meaningful for efficiently increasing urban park accessibility, fully providing services functions of urban park and promoting healthy development of cities to understand objective influencing factors of urban park accessibility and its extent of impact. The service area and service efficiency of urban parks in three-ring area of Shenyang City were evaluated basing on ArcGIS 9.3 software platform and network analysis methods. The regularity of the service area and service efficiency of urban parks changing with the urban park area, urban park shape and road network density were analyzed. The results showed that urban park area had significant positive correlation with service area and significant negative correlation with service efficiency. Urban park shape had significant positive correlation with service area and service efficiency. Road network density had significant negative correlation with service area of urban parks, but had no significant correlation with service efficiency. Based on the extent of impact on urban park service area, the importance of three influencing factors was in the order of urban park area> road network density > urban park shape. Based on the extent of impact on urban park service efficiency, the importance of three influencing factors was in the order of urban park area> urban park shape > road network density. Urban park area was the most important influencing factor for the service area and service efficiency of urban parks.

Reviews

Research and prospects for response mechanisms of soil respiration to experimental warming

SUN Bao-yu, HAN Guang-xuan

2016, 27(10):  3394-3402.  doi:10.13287/j.1001-9332.201610.037

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Soil respiration (R_s) is the main efflux of carbon pool from soil to atmosphere. Increasing R_s caused by rising temperature can result in significant change in the global carbon balance. Global mean land-surface temperature is predicted to rise by 0.3-4.8 ℃ by the end of 21 century. Therefore, how R_s responds to simulated experimental warming in the natural field is one of the critical issues in global change research. Here, we reviewed the response characteristics of R_s to simulated warming under different temporal and spatial patterns. Experimental warming can increase R_s at the short time scale, but there was no uniform law in the long-term warming experiments, and there were differences among different ecosystems. This paper also reviewed the mechanism underlying the simulated warming response of R_s. Warming can directly affect R_s, and warming can also affect R_s indirectly by affecting the environmental factors (e.g., soil water, soil salt, soil physical and che-mical properties), and the regulation of biological factors (e.g., photosynthesis, litter decomposition). Furthermore, we synthesized the formation mechanism of adaptability of R_s to warming, including adaptability of microbes, roots and enzymes to warming, water restriction, and regulation by excessive nitrogen and the substrate supply. Finally, the future research directions were proposed. The study of micro-ecosystem of rhizosphere, characteristics and mechanism of R_s under asymmetric warming should be strengthened. Also, more attention should be paid to the measurement of R_s in typical phenological periods and typical weather in different seasons. The research network of R_s response to simulated warming should be constructed for networking test.