Table of Content

18 March 2017, Volume 28 Issue 3

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CONTENTS

Carbon storage and its allocation in karst forest at different stand ages in Guangxi, China

HU Fang, DU Hu, ZENG Fu-ping, SONG Tong-qing, PENG Wan-xia, LAN Si-an, ZHANG Fang

2017, 28(3):  721-729.  doi:10.13287/j.1001-9332.201703.039

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Based on a survey of 45 plots (1000 m² each) of five different stand ages, i.e., young, middle-aged, pre-mature, mature, and over-mature plantations in the main production area of karst forest in Guangxi, carbon (C) storage and its allocation in vegetation and soil were studied. The results showed that the carbon storage of karst plantations in Guangxi changed in an increasing order of young plantation (86.03 t·hm^-2), near-mature plantation (110.63 t·hm^-2), middle-aged plantation (112.11 t·hm^-2), mature plantation (149.1 t·hm^-2), and then over-mature plantation (244.38 t·hm^-2). The carbon storage distribution varied in both different vegetation la-yers and different stand ages. Tree layer was found to store the greatest amount of carbon by accounting for up to 92.3%-98.7% of total vegetation carbon. The proportion of carbon stored in the tree layer increased with stand age. The proportions of carbon stored in the shrub layer, herb layer, litter and root were 0.3%-1.9%, 0.3%-1.2%, 0.3%-2.5% and 0.3%-3.3%, respectively. Soil organic carbon density decreased as soil depth increased. The soil organic carbon storage over the whole soil profile ranged from 51.75 t·hm^-2 to 81.21 t·hm^-2. The proportion of soil organic carbon in total ecosystem carbon in karst forest ranged from 33.2% to 66.2%, which decreased with stand age. The carbon storage for aboveground and underground parts were 22.80-141.72 t·hm^-2 and 62.30-102.66 t·hm^-2, respectively. Total ecosystem carbon storage was greater in underground part than in aboveground part except mature plantation. The carbon storage in aboveground part carbon increased with stand age but that in underground part changed insignificantly with the carbon storage of soil. The soil and tree layer were the major carbon pools of the forest ecosystems in the karst region, and the sum of carbon stored in soil and tree accounted for more than 96% of total ecosystem carbon storage.

Seasonal dynamics of soil mineral nitrogen pools and nitrogen mineralization rate in different forests in subtropical China

XIAO Hao-yan, LIU Bao, YU Zai-peng, WAN Xiao-hua, SANG Chang-peng, ZHOU Fu-wei, HUANG Zhi-qun

2017, 28(3):  730-738.  doi:10.13287/j.1001-9332.201703.036

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We conducted an in situ incubation experiment to determine soil mineral N (NH₄⁺-N and NO₃^--N) concentrations and soil net N mineralization rates (net ammonification rate and net nitrification rate) using close-top PVC tubes in three adjacent forests (natural forest, Castanopsis kawakamii and Cunninghamia lanceolata plantation) from September 2014 to August 2015 in subtropical China, investigating the effects of forest type and season on soil inorganic N concentrations and soil net N mineralization rates. Results showed that soil NO₃^--N was the dominant form in mi-neral N pool in all three forests, and the proportion of NO₃^--N to soil inorganic N content ranged from 55.1% to 87.5% and from 56.1% to 79.1% in natural forest and Cunninghamia lanceolata plantation, respectively. The effects of forest types on soil mineral N pool were only significant on soil NO₃^--N, and the concentration of NO₃^--N in Castanopsis kawakamii was significantly lower than in the other two forests. The NO₃^--N and mineral N pool varied seasonally in all forests, and were higher in dormant season (October to February) than in growing season (March to September). Soil nitrification rate was very low in the whole year in all three forests and soil net ammonification was the major process of soil net mineralization. Tree species significantly affected soil net ammonification rate, and the value under Chinese fir was significantly lower than the other two fore-sts. The seasonal patterns of the soil net ammonification rate were not similar in all the three forests, but with the lowest value occurring in November and February in the following year. Analysis using variance of repeated measures indicated that soil mineral N concentrations and soil N mineralization rates were significantly affected by forest type and season, and correlation analysis showed that soil mineral N and soil N mineralization rate were significantly affected by water moisture and temperature, and the effects of litter on soil N mineralization rate were mainly through quality control, ra-ther than the quantity control.

CONTENTS

Characteristics of main layer and regeneration layer of Haloxylon ammodendron plantations at different ages on the southern edge of the Gurbantunggut Desert, Northwest China

CHEN Qi-min, LUO Qing-hong, NING Hu-sen, ZHAO Cheng-yi, DUAN Wen-biao

2017, 28(3):  739-747.  doi:10.13287/j.1001-9332.201703.030

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The population structure characteristics, natural regeneration, and the influential factors of Haloxylon ammodendron plantations at six different stand ages on the southern edge of the Gurbantunggut Desert were studied. The results showed that H. ammodendron plantation at the stand age of 7 could naturally regenerate. At the stand age of 17, the densities of the seedlings (＜30 cm height), saplings (30≤H＜50 height), and small trees (≥50 cm height) reached optimal class, and the mean height and base diameter of the small tress reached 1.10 m and 1.91 cm, respectively. The parent trees in H. ammodendron plantation at the stand age of 20 grew best. The height of 35% individuals grew up to 2.50-3.00 m, and the basal stem diameter of 23.1% individuals grew up to 8.00-10.00 cm. The height and diameter growth of the parent trees in H. ammodendron plantation at the stand age of 33 apparently declined, but the regeneration ability by natural seed dispersal was still strong. The regeneration density of natural seed dispersal showed the greatest correlation with the available nitrogen content in 0-100 cm soil layer (0.87), followed by the soil rapidly available phosphorus content (0.84) and the soil water content (0.79). The soils with pH 8.1-8.6 did not limit the nutrient growth of the regeneration layer. In the main stand layer, the individual density of whole regeneration layer showed the greatest correlation with the biomass of the parent trees (0.77), while the density of regeneration layer of the small trees showed the greatest correlation with the planting density (0.71) and the age of the parent trees (0.70).

Phenotypic variations in cones and seeds of natural Cupressus chengiana populations in China

FENG Qiu-hong, SHI Zuo-min, XU Zheng-jing-ru, MIAO Ning, TANG Jing-chao, LIU Xing-liang, ZHANG Lei

2017, 28(3):  748-756.  doi:10.13287/j.1001-9332.201703.001

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A total of 13 phenotypic traits from 11 natural populations of Cupressus chengiana were investigated by using nested analysis, variation coefficient, phenotypic traits differentiation coefficient, and un-weighted pair-group method by arithmetic averages (UPGMA) cluster analysis. Phenotypic variations among and within populations of C. chengiana were discussed, the relationship among phenotypic traits and that between phenotypic traits and environmental factors were analyzed, and the 11 populations were divided. The results showed that there was significant difference in phenotypic variation both between and within populations. Variation within populations (49.7%) was greater than that between populations (28.6%). The mean coefficient of phenotypic differentiation between populations was 43.4% suggesting the differentiation between populations was relatively larger. The average variation coefficient of cone mass was the highest (37.2%), followed by seed mass in single cone, and that of cone length was the smallest (8.0%) indicating the cone length was the most stable phenotypic trait. The phenotypic diversity was greatest in Kangding County and smallest in Wudu County. The mean annual temperature of the hottest month and mean annual precipitation of growing season were the main environmental factors on phenotypic diversity in cones and seeds of C. chengiana in the study region. According to the 13 phenotypic traits, the 11 populations could be divided into two groups and three subgroups, which showed how C. chengiana distributed in three watersheds. Phenotypic traits in cones and seeds of C. chengiana populations were the best in Daduhe River watershed, and those were the worst in Minjiang River watershed.

CONTENTS

Foliage clumping index of main vegetation types in Daxing’an Mountains, Northeast China

HUANG Ting, FAN Wen-yi, MAO Xue-gang, YU Ying

2017, 28(3):  757-762.  doi:10.13287/j.1001-9332.201703.011

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The foliage clumping index quantifies the cluster degree of the leaf spatial distribution under random canopy. It is of comparable importance for establishment of ecological models. MODIS BRDF model parameter products (MCD43A1 data) and land cover types (MCD12Q1 data) were used in this study to simulate the reflectivity of the hot spots and dark spots, and calculate the normalized difference between hotspot and darkspot (NDHD) based on the Ross-Li semi-empirical model. Least square method was then used to simulate the relationship between NDHD and the foliage clumping index and foliage clumping index products of 500-m resolution in August 2014 were retrieved. Measurements of the foliage clumping index in Daxing’an Mountains were conducted by using the TRAC (Tracing Radiation and Architecture of Canopies) sampling instrument for mo-del validation and analysis. Results showed that it was a feasible algorithm to retrieve clumping index from MCD43A1 product with the correlation of simulated data and the measured data of significance (R²=0.8879). The MODIS near infrared wave band was more sensitive than that on red band to foliage clumping index change. With the increase of the solar zenith angle, the clumping index retrieved by Ross-Li model had a linear increase (R²=0.9699), which indicated that the foliage clumping index related to the solar zenith angle.

Characteristics and affecting factors of sap flow density of Pinus tabuliformis and Hippophae rhamnoides in growing season in the hilly region of the Loess Plateau, China

WEN Jie, CHEN Yun-ming,TANG Ya-kun,WU Xu, XIE Yu-li,CUI Gao-yang

2017, 28(3):  763-771.  doi:10.13287/j.1001-9332.201703.034

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The dynamic changes of sap flow density (J_s) of Pinus tabuliformis and Hippophae rhamnoides in plantations from July to September in 2015 was monitored through thermal dissipation probe in the hilly region of the Loess Plateau. In addition, plant physiological characteristics were analyzed to determine the water use types of these two species. The results indicated that the daily changes of J_s of P. tabuliformis and H. rhamnoides showed a single peak during both pre- and post-precipitation. The J_s of P. tabuliformis in growing season (12.62 mL·m^-2·s^-1) was significantly higher than that of H. rhamnoides (2.60 mL·m^-2·s^-1). The J_s of these two species were significantly positively correlated with photosynthetic active radiation, vapor pressure deficit, soil volume-tric water content (SWC). The J_s of these two species were mainly influenced by meteorological factors during pre- and post-precipitation in both August and September. The contribution of SWC to J_s of H. rhamnoides increased by 4.2% after precipitation in September, but the contribution of SWC to J_s of P. tabuliformis decreased by 0.3% after precipitation in both August and September, respectively. Meanwhile, P. tabuliformis showed significantly higher water potential in midday leaf, but lower coefficient of variation (7.3%) than H. rhamnoides with the coefficient of variation of 11.7%. However, H. rhamnoides exhibited higher leaf stomatal conductance. Thus, P. tabuliformis and H. rhamnoides could be considered as isohydry and anisohydry species, respectively.

Latitude variation mechanism of leaf traits of Metasequoia glyptostroboides in eastern coastal China

GUO Wei-hong, WANG Hua, YU Mu-kui, WU Tong-gui, HAN You-zhi

2017, 28(3):  772-778.  doi:10.13287/j.1001-9332.201703.032

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We analyzed the rules of Metasequoia glyptostroboides along with latitude, including leaf length, leaf width, leaf perimeter, leaf area, ratio of leaf length to width, specific leaf area (SLA), and leaf dry mass based on eight stands growing at different latitudes in the coastal area of eastern China, as well as their relationships with climatic and soil factors. The results showed that the leaf length, leaf width and leaf perimeter increased with increasing latitude, while the leaf area and SLA firstly increased and then decreased. The mean annual temperature and annual precipitation were the major environmental factors affecting the leaf traits along latitude gradient. With the increase of soil N content, the SLA decreased firstly and then increased, while the leaf mass decreased significantly. With the increase of soil P content, the SLA increased, and the leaf mass decreased significantly.

A two-step approach for modeling tree mortality in Larix olgensis plantation based on effects of thinning

WANG Meng, LI Feng-ri, JIN Xing-ji

2017, 28(3):  779-788.  doi:10.13287/j.1001-9332.201703.014

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Ten permanent plots of Larix olgensis plantation were established in 1972 and 1974 at Jiangshanjiao and Mengjiagang forest farms in Heilongjiang Province, respectively. The plots including 8 thinning plots and 2 control plots were measured annually. The effects of thinning on the probability of plot mortality and individual tree mortality were analyzed. Based on the binary logistic regression, two-step models of the probability of mortality were developed. The approach consisted of estimating the probability of mortality after thinning on a sample plot (Ⅰ) and the mortality of individual tree within mortality plots (Ⅱ). The generalized estimating equations (GEE) method was adopted to estimate the parameters of models. An optimal cutpoint was determined for each model by plotting the sensitivity curve and the specificity curve and choosing the cutpoint at which the specificity and sensitivity curves cross. The results showed that four models (models 1-4) were developed based on the data of plots which was divided into 4 groups by thinning times, respectively. The significant explicatory variables of model 1 were site index, the logarithm of stand age, thinning age and thinning intensity. Principal component analysis was used to develop models 2-4. The primal variables of the principal components were stand age, tree numbers per hectare, mean square diameter at breast height and thinning factors. This showed that thinning significantly affected the probability of plot mortality. The effect of thinning was not significant for the pro-bability of individual tree mortality. The significant variables of the individual tree mortality model were planting density, age, the inverse of diameter at breast height and the basal area of all trees larger than the subject tree. Hosmer and Lemeshow goodness of fit tests were not significant for the mortality models of plots and individual trees (P＞0.05). The areas under the receiver operating characteristic curve (AUC) of the models were all greater than 0.91, the accuracies were all above 80%, suggesting the fitting results of the models performed very well.

CONTENTS

Effects of shading in summer and autumn on physiological and biochemical characteristics of ‘Huangjinya’ in Shandong Province, China

TIAN Yue-yue, ZHANG Li-xia, ZHANG Zheng-qun, QIAO Ming-ming, FAN Yan-gen

2017, 28(3):  789-796.  doi:10.13287/j.1001-9332.201703.004

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In order to ensure the suitable shade model for ‘Huangjinya’ tea plant in Shandong Province, black or blue shading net at 55%, 70% or 85% shading rates was selected to recover tea garden in summer and autumn, then micro-climate of tea garden, leaf color, chlorophyll fluorescence parameters, growth status and biochemical composition of tea shoots were investigated.The results showed that compared with the control, light intensity and air temperature in tea garden, leaf temperature of tea plants in different shading treatments significantly decreased, while air humidity in tea garden increased. The contents of chlorophyll in the tea leaves were obviously increased with increasing the shading rate, which resulted in the leaf color becoming green. The yellowing characteristics and biochemical quality of ‘Huangjinya’ tea plants could be well kept in 55% shading treatments. In 70% shading treatments, ‘Huangjinya’ tea plants had better growth situation and higher yield with no photo-inhibition. Compared with the blue shading treatments, black shading treatments could obviously promote the growth of ‘Huangjinya’ tea plants, keep yellowing characteristics, and improve the quality. Therefore, the 70% black shading treatment (daily PAR values of 1.2-3.5 ten thousand lx) was appropriate for promoting the growth of ‘Huangjinya’ tea plants at the seedling stage. For mature tea plants, the 55% black shading treatment (daily PAR values of 1.8-5.5 ten thousand lx) could be used to keep the yellowing characteristics and to improve biochemical quality effectively, so as to give full play to its variety characteristics, to achieve goal of high quality and high yield.

Effects of water level fluctuation on the inter- and intra-specific relationships between Wedelia trilobata and W. chinensis

BU Xiang-qi, LIU Lin, MU Ya-nan, GUAN Yu-ting, LI Hong-li, YU Fei-hai

2017, 28(3):  797-804.  doi:10.13287/j.1001-9332.201703.029

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A controlled greenhouse experiment was designed with the invasive Wedelia trilobata and native W. chinensis. Three water level fluctuation treatments (no fluctuation, change pattern by 15 cm-0 cm-15 cm, change pattern by 0 cm-15 cm-0 cm) were crossed with five plant arrangement treatments (an individual invasive plant per pot, an individual native plant per pot, 6 invasive plants per pot, 6 native plants per pot, six plants per pot with three invasive and three native plants) to explore the effects of water level fluctuation on inter- and intra-specific relationships between W. trilobata and W. chinensis. The results showed that water level fluctuation decreased signifi-cantly the total biomass, stem biomass, leaf biomass, root biomass, stem length, number of nodes, number of leaves and leaf area of W. trilobata and W. chinensis. Meantime it had significant effects on the inter- and intra-specific competition between W. trilobata and W. chinensis. Water level fluctuation changed the inter- and intra-specific competition of W. trilobata. It indicated that W. trilobata was more sensitive to water level fluctuation with stronger adaptability.

Soil methanotrophic community structure and diversity in different vegetation types at elevation gradient of Gongga Mountain, Southwest China

LI Chao-nan, LI Jia-bao,LI Xiang-zhen

2017, 28(3):  805-814.  doi:10.13287/j.1001-9332.201703.012

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Methane (CH₄) is the second abundant greenhouse gas. Aerobic methane oxidations of topsoil in forest are identified as an important sink of atmosphere methane, playing critical roles in carbon cycle and global warming alleviation. Comparing the community structure and diversity of methane oxidizing bacteria (MOBs) in different vegetation ecosystems could provide new insights into the relationships between vegetation types and community of MOBs. In this study, we collected 92 soil samples from four types of vegetation along the elevation gradient of Gongga Mountain, and further assessed the community structure, diversity and potential drivers of MOBs across the four vegetation types using Miseq sequencing and bioinformatics methods. The result indicated that MOBs community compositions in evergreen and deciduous broad-leaved forest (EDBF) and coniferous and broad-leaved mixed forest (CBMF) was more similar, whereas in dark coniferous forest (DCF) and shrub meadow area (SMA) soils, MOB composition was more similar. In the four types of vegetation, α-diversities of MOBs in EDBF and CBMF were significantly higher than that in the other three vegetation types (P＜0.001), whereas β-diversities in soils of DCF and SMA were significantly higher than those in EDBF and CBMF (P＜0.001). Spearman analysis indicated that the relative abundance of different MOBs in four types of vegetation showed different responses to environmental change. Factors including soil total nitrogen, conductivity and soil temperature appeared to govern the variation of α-diversity across the four vegetation types. Partial Mantel test and redundancy ana-lysis (RDA) suggested that environmental parameters likely contributed more to diversity variations in soils from EDBF and CBMF, whereas diversity variations in soils from DCF and SAM might be driven by other potential environmental factors or mechanism. Precipitation appeared to drive the β-diversity variation between vegetation of EDBF and CBMF and vegetation of DCF and SAM. Our study suggested that the community structure and diversity variation of MOBs in different vegetation types might be governed by both soil properties and climate change.

Ecological distribution and genetic relation of endophytic fungi in Cynomorium songaricum and its host Nitraria tangutorum

WANG Meng-liang, JIA Yan, CUI Jin-long, WANG Jun-hong

2017, 28(3):  815-820.  doi:10.13287/j.1001-9332.201703.008

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This is the first report of the distribution and genetic relationships of endophytic fungi from the parasitic plant Cynomorium songaricum and its host Nitraria tangutorum. Endophytic fungi from the root of natural N. tangutorum, parasitic plant C. songaricum and its host N. tangutorum were isolated by tissue culture, and they were identified by morphology combined with molecular barcoding based on ITS-rDNA sequence. The isolation rates, colonization rates, isolation frequency, diversity index, evenness index, similarity coefficient and genetic relationships among fungal taxa were estimated by phylogenetic analysis, and differences in fungal endophyte distribution were investigated. The results showed that a total of 49 isolates were obtained belonging to 18 different taxa. 95.9% of these taxa were in Ascomycota, and the remaining was in Basidiomycota (4.1%). The isolation rate and colonization rate of endophytic fungi were 15.3% and 25.0%, respectively. The Shannon biodiversity index was the highest in the root of natural N. tangutorum at 2.13. The simila-rity coefficient was highest between the stem of C. songaricum and the flower of C. songaricum at0.50. Fusarium was the dominant genus in N. tangutorum, while Penicillium was the primary genus in C. songaricum. The differential distribution of fungal taxa between N. tangutorum and C. songaricum suggested that the parasitic relationship influences the endophytic fungal community.

Impacts of climate change on maize potential productivity in Northeast China and the simulation of control measures: A case study of Jilin Province, China

CHEN Ming, KOU Wen-hong, LI Yu-huan, MAO Wei-bing, SUN Cui-shan, CHEN Shi-geng

2017, 28(3):  821-828.  doi:10.13287/j.1001-9332.201703.038

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In this study, we collected data of meteorology, soil property, agricultural management and corn yield from five representative sites in Jilin Province, China, and integrated these data into a crop growth model of CERES-maize to simulate the potential productivity of five corn varieties. Our objectives were to simulate, calibrate and validate genetic parameters of the corns based on the analyses of climatic effects on the productivity, and to establish best practices for enhancing crop production in response to climatic change. The results showed that the projected days of sowing-flo-wering and flowering-maturing stages and yields of corn were well consistent with the measured va-lues with normalized mean variances being 2.96%, 3.40% and 9.37%, respectively, and the stan-dard deviation ranged from -10.6% to 15.2%. The mean projected light-temperature potential productivity (LTPP) of corns ranged from 7799.60 to 12902.83 kg·hm^-2·a^-1, which decreased by 128.6-880.3 kg·hm^-2 every 10 years. The correlation analysis suggested that climate change, i.e. temperature rising and significant decline of total radiation during the growth of corns, dominated the decrease of LTPP of corns in the region. The simulated genetic parameters indicated that the LTPP of the corns increased linearly with the increase of P5 (filling stage characteristic parameter referred to silking to physiological maturity of more than 8 ℃ heat time). Our model estimated that the LTPP might increase 154.44-261.10 kg·hm^-2 for every 10 ℃·d increase of P5. The simulated sowing date delay showed that five days’ sowing delay would maximize the LTPP of corns in Dunhua and Liaoyuan with 0.47% and 1.32% increase, respectively, while 15 days’ delay would maximize the LTPP in Huadian and Yushu with 1.10% and 4.06% increase, respectively.

Dynamics of soil physical properties and biological soil crust during the vegetation restoration process of abandoned croplands in the Ordos Plateau, China

CAI Wen-tao, LI He-yi, LAI Li-ming, ZHANG Xiao-long, GUAN Tian-yu, ZHOU Ji-hua, JIANG Lian-he, ZHENG Yuan-run

2017, 28(3):  829-837.  doi:10.13287/j.1001-9332.201703.031

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A series of typical abandoned croplands in the regions of Ruanliang and Yingliang in the Ordos Plateau, China, were selected, and dynamics of the surface litter, biological soil crust and soil bulk density, soil texture, and soil moisture in different soil layers were investigated. The results showed that in the abandoned cropland in Ruanliang, the clay particle content and surface litter of the surface soil layer (0-10 cm) increased during the restoration process, while that of soil bulk density substantially decreased and soil water content slightly increased in the surface soil. In the medium soil layer (10-30 cm), the clay particle content increased and the soil water content slightly decreased. In the deep soil layer (30-50 cm), there was a relatively large variation in the physical properties. In the abandoned cropland in Yingliang, the coverage of litter and the coverage and thickness of the biological soil crust increased during the abandonment process. The surface soil bulk density, soil clay particle content and soil water content remained constant in 0-10 cm soil layer, while the physical properties varied substantially in 10-40 cm soil layer. The shallow distribution of the soil water content caused by the accumulation of the litter and clay particles on the soil surface might be the key reason of the replacement of the semi-shrub Artemisia ordosica community with a perennial grass community over the last 20 years of the abandoned cropland in Ruanliang. The relatively high soil water content in the shallow layer and the development of the biological soil crust might explain why the abandoned cropland in Yingliang was not invaded by the semi-shrub A. ordosica during the restoration process.

Effects of long-term fertilization on soil fertility in yellow fluvo-aquic soil

WEI Meng, ZHANG Ai-jun, ZHUGE Yu-ping, LI Hong-min, TANG Zhong-hou, CHEN Xiao-guang, LOU Yan-hong, WANG Hui

2017, 28(3):  838-846.  doi:10.13287/j.1001-9332.201703.027

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Based on the long-term field fertilization experiment in yellow fluvo-aquic soil, this study selected 2 types of soil physical, 8 items of soil chemical, and 5 soil biological properties for principal component-cluster analysis to valuate comprehensively effects of long-term fertilization on soil fertility. Results showed that significant differences of soil properties were found among the fertilization treatments. Compared with no organic manure treatment (NPK), all treatments of organic manure (M) or its combination with inorganic fertilizers (MN, MNP, MNPK) significantly reduced soil bulk density, and increased soil total porosity, the contents of soil organic carbon, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, microbial biomass, and activities of catalase, urease, alkaline phosphatase and invertase. Two principal components that could reflect 85.5% of the original information quantity without losing any original variables were extracted from the initial 15 indices. Within the primary group of principal components, bulk density, total porosity, organic matter, total nitrogen, alkali-hydrolyzable nitrogen, total phosphorous, available phosphorus, available potassium,microbial biomass, catalase, urease, alkaline phosphatase and inver-tase were the major contributors, while among the secondary group of principal components, total potassium and pH were the major ones. Hierarchical cluster analysis of the new indices extracted based on scores of the two principal components revealed the effects of different patterns of long-term fertilization displayed an order of MNPK＞MNP＞M, MN＞NPK＞N, NP＞CK. In conclusion, organic fertilizer has the positive effect on improving soil fertility, and combined application of organic and N, P, K fertilizer is the best fertilizing model.

Effects of land use types on deep soil water content in the loess hilly area of the north Shaanxi Province, China

LAN Zhi-long, PAN Xiao-lian, ZHAO Ying, SI Bing-cheng, WANG You-ke, JIAO Rui, ZHANG Jian-guo

2017, 28(3):  847-855.  doi:10.13287/j.1001-9332.201703.005

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This study explored the differences of soil water content at 0-20 m soil depth at three locations, including economical plantation in Mizhi, reforestation area in Shenmu, and wind break and sand fixation forest district of Yuyang, and for clarifying the impacts of different land use types on deep soil water distribution and storage characterization, as well as its eco-environmental effect on the loess hilly area. The results showed that in the soil profile of 0-20 m, land use patterns had a significant impact on soil moisture distribution. There were significant differences of soil water sto-rage for the economical plantation, pruning Ziziphus jujuba plantation ＞ Z. jujuba plantation with 587.9 mm difference. There was no significant difference in soil water storage between Caragana korshinskii plantation and degraded artificial vegetation or between pine forests and natural grass field, degraded artificial grassland ＞ C. korshinskii plantation with 98.8 mm difference at Shenmu, and natural grassland ＞ Pinus sylvestris var. mongolica plantation with 7.5 mm difference at Yuyang. The pruning Z. jujuba tree reduced soil water consumption and was beneficial to sustainable use of soil water due to the decreased crown width and thus reduced transpiration. There were no obvious differences of soil water content between C. korshinskii plantation and degraded artificial grassland due to the historical alfalfa planting which was characterized by high water consumption due to its deep root distribution and large biomass. In contrast, P. sylvestris var. mongolica plantation and na-tural grassland had similar and low averaged soil water contents with 3.4% and 3.6%, respectively, mainly due to the sandy soil texture and weak soil water holding capacity. In addition, with increa-sing soil depth, soil water content increased in this area, indicating the effect of plants on water moisture of deep soil was very limited. Except for the underlying control of soil texture on soil water content in the soil profile, different vegetation played a key role in the dynamics of soil water content due to the difference of root zones. It was very important to choose the suitable type of vegetation regarding the protection and sustainable use of deep soil water.

Effect of application of cow manure and green manure on corn yield and soil physical-chemical properties in land restoration area

XU Da-bing, DENG Jian-qiang, PENG Wu-xing, SI Guo-han, PENG Cheng-lin, YUAN Jia-fu, ZHAO Shu-jun, WANG Rui

2017, 28(3):  856-862.  doi:10.13287/j.1001-9332.201703.024

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The effects of cow manure and green manure on maize yield, soil respiration and soil physical-chemical properties in land restoration area was evaluated through field experiments. The results indicated that the maize yield and thousand-grain mass with cow manure were increased by 7.2%-29.9% and 2.5%-18.2%, respectively compared with the application of chemical fertilizer (CF), while the soil active organic carbon and organic matter contents of cow manure were 5.3%-34.6% and 8.0%-17.6% higher than that obtained in CF. The maize yield and thousand-grain mass were increased by 10.8%-15.6% and 4.5%-8.4% with application of green manure, respectively compared with CF. The content of active organic carbon in green manure was 14.1%-48.6% higher than that detected in CF. In the second year, the content of organic matter in green manure treatment was 7.2% higher than that of CF. The soil respiration rates under cow manure and green manure treatments increased by 20.0%-69.3% compared with CF. CF and green manure could improve the soil bulk density and increase the aggregate ratios of ＜0.01 mm and 0.05-1 mm fractions, respectively. On the other hand, the cow manure and green manure could decrease the soil total porosity and the capillary porosity. In conclusion, the application of cow manure and green manure in land restoration region could increase maize yield during the two consecutive seasons, which showed a positive response to improvement of soil physical-chemical properties.

Effect of sowing dates on cotton yield, fiber quality, and uptake and utilization of nutrients in Inner Mongolia west desert area, China

ZHANG Guo-wei, ZHANG Xiang, CHEN De-hua, ZHOU Zhi-guo

2017, 28(3):  863-870.  doi:10.13287/j.1001-9332.201703.021

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Field experiments were conducted in 2014 and 2015 at the “Inner Mongolia cotton comprehensive test station” (39°27′ N, 105°39′ E) in Alxa Left Banner of Alxa League in Inner Mongolia. By using cotton cultivar CCRI-50 as material and the “6 cotton rows with 3 dripping pipes under a plastic film mulching” plantation pattern, different sowing dates (20-Apr, 30-Apr and 10-May) were set to study the effect of sowing dates on cotton yield, fiber quality and nutrient uptake and utilization. The results showed that as the sowing date delayed, the development of cotton plant was delayed, the yield forming stage shortened, and the mean daily temperature of boll deve-lopment reduced, but the harvesting density increased. Sowing date influenced the biomass accumulation, fiber yield and fiber quality, it also influenced the absorption and distribution of N, P and K. Among the three sowing dates, the biomass distribution proportion to reproductive organ, nutrition (N, P and K) accumulation, lint production efficiency of nutrient and yield were higher in the cotton plant that was sowing at 30-Apr, the seed cotton and lint yield were the highest which could reach up to 6505.9 kg·hm^-2 and 2660.9 kg·hm^-2, respectively, and the fiber quality was better than that of 10-Mar. For the plant which was sowed at 20-Apr, harvesting density, biomass and nutrient accumulation were the lowest, although economic coefficients of biomass and nutrient were the highest, and the seed cotton and lint yield were respectively 10.9%-14.0% and 11.1%-14.2% lower than that of 30-Apr. When sowing at 10-May, cotton could avoid the low temperature during seed germination, but mean daily temperature during boll development were the lowest, although biomass and nutrient accumulation were the highest. The economic index, lint production efficiency of nutrient were the lowest, which leading to the poorest fiber quality, lowest seed cotton and lowest lint yield which were respectively 32.5%-34.7% and 35.9%-36.2% lower than that of 30-Apr. These results suggested that the optimum sowing date for cotton planting was about 30-Apr in Inner Mongolia west desert area.

Impact of tillage and nutrient management practices on the spring weed community in a winter wheat-summer maize rotation farmland

WANG Neng-wei, GE Xiu-li, LI Sheng-dong

2017, 28(3):  871-876.  doi:10.13287/j.1001-9332.201703.015

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Conservation tillage and the weed diversity are two hot issues in the modern ecological agriculture. Although it is known that the diversity of weed would increase slightly in the farmland under conservation tillage, the interaction effects between the tillage and the nutrient management on the weed community are not clear. In this study, one wheat-maize rotation field located in Ji’nan, Shandong Province, was selected as the studying site. Different tillage methods (no-tillage, deep subsoiling, rotary tillage, deep tillage) and different nutrient managements (farmers routine, 480 kg N hm^-2 per year; high production and efficiency, 360 kg N hm^-2 per year; optimal management, 300 kg N hm^-2 per year) were carried out for 3 years. The characteristics of the spring weed communities under different managements were investigated and compared. The results showed that there were 15 species in the spring weed communities in the test filed and Digitaria sanguinalis and Echinochloa crusgalli were the dominant species. The plots under no-tillage or deep subsoiling had higher weed densities compared with those under the deep tillage or rotary tillage. In terms of the effect of tillage on the weed community diversity, both species richness index and species evenness index were lowest but the community dominance index was highest in the plots under deep tillage. In terms of the effect of the nutrient management, with the increase of fertilizer application, both species richness and evenness index increased under the different tillage methods. The community dominance increased with the increasing fertilizer application under deep tillage or rotary tillage and vice versa under no-tillage, deep subsoiling. In terms of weed biomass, the plots under no-tillage or deep subsoiling had significantly higher weed biomass than those under the other two tillage methods. The plots under routine nutrient management had higher weed biomass than those under the other two nutrient managements. Among all these treatments, the plots under the combination treatment of no-tillage and routine nutrient management had the highest weed biomass. According to these results, it was implied that no-tillage and fertilization would improve species richness index, species evenness index, and the productivity of spring weed community in the wheat-maize farmland.

Effects of supplemental irrigation by measuring soil moisture on water consumption chara-cteristics and radiation utilization in wheat

ZHANG Rui, YU Zhen-wen, ZHANG Yong-li, SHI Yu, ZHAO Jun-ye

2017, 28(3):  877-884.  doi:10.13287/j.1001-9332.201703.037

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Field experiments were conducted during 2013-2014 and 2014-2015 winter wheat growing seasons by using Jimai 22 as test material. Five treatments were designed: W₀(non-irrigation during growth season), W₁(non-irrigation at overwintering, but irrigated to 65% of field capacity (FC) at jointing and 70% of FC at anthesis in 0-40 cm soil layer), W₂(irrigated to 70% of FC at overwintering, 65% of FC at jointing and 70% of FC at anthesis in 0-40cm soil layer, respectively) and W₃(irrigated to 75% of FC at overwintering, 65% of FC at jointing and 70% of FC at anthesis in 0-40cm soil layer, respectively), W₄(irrigated 60 mm at overwintering, jointing and anthesis stages, respectively). The aim was to clarify the effects of supplemental irrigation on water consumption characteristics and photosynthetically active radiation utilization in wheat. Results showed that the total irrigation amount and its ratio to total water consumption in each treatment were ranked as W₄＞W₃＞W₂＞W₁＞W₀. However, the percentage of water consumption in soil to total water consumption was presented as W₀＞W₁, W₂＞W₃, W₄. The total water consumption, water consumption from anthesis to maturity were ranked as W₄＞W₂, W₃＞W₁＞W₀. The order of photosynthetically active radiation (PAR) capture ratio was W₄＞W₂, W₃＞W₁＞W₀, but the order was contrary in PAR reflect ratio among the treatments. The net accumulation of dry matter was ranked as W₄＞W₂＞W₃＞W₁＞W₀ in the two growing seasons. During the two winter wheat growing seasons, the grain yield in W₂ was higher than in the other treatments, except W₄, but the irrigation efficiency and water use efficiency in W₂ were the highest. Concerning both the high-yield and high-water use efficiency in this experiment, the most appropriate irrigation regime was W₂ treatment.

Effects of tillage practices on photosynthetic performance diurnal variation during filling stage and grain yield of winter wheat

ZHANG Xiang-qian, ZHAO Xiu-ling, WANG Yu-qiao, PU Chao, BAOER Jiang-mahemuti, CHEN Fu, ZHANG Hai-lin

2017, 28(3):  885-893.  doi:10.13287/j.1001-9332.201703.020

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Photosynthesis characteristics of winter wheat under different tillage practices during fil-ling stage are vital for dry matter accumulation, transfer, and yield development. A field experiment, including no-till with residue removal (NT), no-till with residue retention (NTS), rotary tillage with residue removal (RT), rotary tillage with residue retained (RTS), subsoiling with residue removal (DT), subsoiling with residue retained (DTS), plow tillage with residue removal (CT), and plow tillage with residue retained (CTS) was conducted at Wuqiao experimental station of China Agricultural University since October 2008. The diurnal variation of photosynthetic characteristics of flag leaf, photosynthetic response curve, and crop yield under different tillage practices were evaluated during winter wheat filing stage in this study. The results showed thatthe net photosynthetic rate and stomatal conductance of flag leaf both diurnally varied with the bimodal curve, and the net photosynthetic rates were higher under treatments with residue retained than those under with residue removal. Diurnal variation of intercellular carbon dioxide concentration was observed with a “V-shaped wide mouth” bimodal curve under all treatments. Daily transpiration rate exhibited “double peak curve”, except for the “single peak curve” under DTS, RTS and RT. The stimulated net photosynthetic rate was increased by 20.0%, 21.7%, 19.7%, 21.5%, 0.8%, 12.1% and 4.2% under NT, DT, RT, CT, CTS, RTS, and CTS, compared with DTS, respectively. Photosynthetic response curves were fitted better under treatments with residue retained than under treatments with residue removal. As for crop grain yields, the highest one was observed under DTS, following by RTS and CTS, and the lowest under CT. Crop grain yield was increased by 10.8%, 1.3%, 2.1%, 5.4%, 11.9%, 12.4%, and 12.6% under DTS, compared with NTS, RTS, CTS, NT, DT, RT, and CT, respectively. Thus, residue retaining under different tillage practices (e.g. NTS and DTS) could mitigate the mid-day depression of photosynthesis, maintain a high photosynthetic rate of winter wheat, and improve the dry matter accumulation and crop production.

Effects of exogenous Ca²⁺ on growth and development, physiology and yield of peanut under salt stress

YANG Sha, HOU Lin-lin, GUO Feng, ZHANG Jia-lei, GENG Yun, MENG Jing-jing,LI Xin-guo, WAN Shu-bo

2017, 28(3):  894-900.  doi:10.13287/j.1001-9332.201703.016

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Huayu 22, one of the peanut (Arachis hypogaea) cultivars, was used as material in this study. Peanuts, which grew under normal conditions and 100 mmol·L^-1 NaCl stress, were treated with 0, 6, 12 mmol·L^-1 Ca(NO₃)₂ respectively to elucidate the effects of exogenous calcium on peanut salt tolerance. The effects of different Ca²⁺ concentrations on the physiological indices and yield of peanut during the whole growth period under salt stress were investigated in potted plants, with the aim to provide theoretical basis for the growth and production of peanut in saline soil. The results showed that, under salt stress, the activities of superoxide dismutase (SOD), catalase (CAT), and chlorophyll content increased whereas the MDA content and electrolytes decreased when treated with different concentrations of exogenous calcium. Calcium also improved root activity, biomass, improved agronomic traits, and finally increased peanut yield. Among all the exogenous calcium treatments, the effect of 12 mmol·L^-1 Ca²⁺ treatment was the most significant. These results indicated that exogenous calcium could alleviate the salt stress on peanut plants and enhance the yield of pods by enhancing the scavenging ability of active oxygen, maintaining the stability and integrity of cell membrane.

Effects of iron deficiency and NO₃^- stress on tomato seedlings growth and iron absorption under suboptimal temperature

HE Ming-ming, WANG Xiu-feng, HAN Hui-hui, JIA Hai-chen, WEI Min, SHI Qing-hua, YANG Feng-juan

2017, 28(3):  901-910.  doi:10.13287/j.1001-9332.201703.017

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The effects of iron deficiency and NO₃^- stress on the growth and the iron absorption cha-racteristic of tomato seedlings were investigated under suboptimal temperature (18 ℃/12 ℃ (day/night)). The results indicated that the growth was significantly inhibited under suboptimal temperature compared with appropriate temperature treatment; the plant heights, leaf areas and dry matter accumulations were markedly decreased. The effects of iron deficiency under suboptimal temperature on the growth of tomato seedlings were larger than that of under appropriate temperature treatments. Under suboptimal temperature, the plant heights of tomato seedlings in iron deficiency and/or NO₃^- stress treatments were not significantly different from no stress treatment, but leaf areas and leaf chlorophyll content of tomato seedlings were decreased obviously. The leaf electrolytic leakage, root activity and Fe³⁺ reductase activity of tomato seedlings were markedly increased under suboptimal temperature, but chlorophyll content, total root length, root surface area, root tip number and root volume were obviously reduced. The iron contents in roots, stems and leaves of tomato seedlings were also remarkably decreased. The NO₃^- stress and the combined stress of iron deficiency and NO₃^- stress under suboptimal temperature aggravated the reduction of dry matter, leaf electrolytic leakage and the inhibition of iron ion absorption in tomato seedlings. The iron ion absorption showed the antagonistic impact on the absorption of potassium and calcium ion, but showed different effects among different organs. The iron deficiency symptom of tomato seedlings was aggravated by reducing the concentration of iron ion in the nutrient solution.

Yield reduction risk based on WOFOST model and water stress for winter wheat in Henan Province, China

LI Shu-yan, YU Wei-dong

2017, 28(3):  911-917.  doi:10.13287/j.1001-9332.201703.019

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The main wheat production area in Henan Province was classified into five regions based on observed wheat production data, historical meteorological data and soil data from thirty sites du-ring 1981 to 2014. The changes in the risk of yield loss of winter wheat under water stress condition in each region were calculated with WOFOST model. From 1981 to 2014, the yield reduction rate of winter wheat showed an increasing trend at all the sites with the increase rate of 2.8%-5.0% per 10 years. The yield reduction rate decreased from north to south in Henan Province. The event of yield reduction rate over 20% occurred about once every 10 years in southern Henan Province, and once every 2 years at Xinxiang, Fengqiu and Puyang in northern Henan Province. The event of yield reduction rate over 50% occurred about once every 3 years at Xinxiang and Zhengzhou but was rare in southern Henan Province. The highest hazard areas were mainly distributed in north and middle parts of Henan Province, the lowest hazard areas were distributed at Lushi in western Henan Pro-vince, Nanyang in southwestern Henan Province, Xinyang in southern Henan Province and south part of Zhumadian, the medium hazard areas were distributed in the other regions of Henan Province.

Simulation of AquaCrop model and management practice optimization for dryland maize production under whole plastic-film mulching on double ridges

ZHANG Tao, SUN Wei, ZHANG Feng-wei, SUN Bu-gong, WANG Ting, WU Jian-min

2017, 28(3):  918-926.  doi:10.13287/j.1001-9332.201703.025

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In order to study the applicability of AquaCrop model for simulating dryland whole plastic-film mulching in double ridges cultivation mode and to find the best agronomic management measures, the data of nitrogen gradient test in 2014 and 2015 were selected to validate the variety and stress parameters in the model. The change trends of yield were simulated under different mana-gement measures. The results showed that the root mean square error (RMSE), normalized root mean square error (NRMSE) and the compliance index (d) of the measured and simulated production for all treatments were 717 kg·hm^-2, 10.0% and 0.96, respectively, the RMSE, NRMSE and d of the total biomass were 951 kg·hm^-2, 6.5% and 0.98, respectively, which indicated that the cultivation characteristics of the whole plastic-film mulching on double ridges maize in the dryland could be well reflected. The best fitting degree was 270 kg N·hm^-2 from dynamic simulation analysis of canopy cover degrees and biomass, and with the increase of N stress, the simulation accuracy gradually declined. The best sowing time of the whole plastic-film mulching on double ridges maize in the middle part of Gansu Province was from late April to early May, the seeding density was 45000-65000 plants·hm^-2, the growth period was 130-145 days, and the nitrogen application rate was 240-280 kg·hm^-2. The results of this study had a certain reference value for the application of AcquaCrop model in arid region of Gansu, and would contribute to the transformation and popularization of agricultural cultivation techniques.

Effects of optimized fertilization on nematode community in greenhouse soils

ZHU Tong-bin, CHEN Xiao-yun, ZHANG Jin-bo, LIU Man-qiang, ZHOU Ke-xin, CAI Zu-cong

2017, 28(3):  927-934.  doi:10.13287/j.1001-9332.201703.006

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Excessive fertilization easily leads to the degradation of greenhouse vegetable fields, therefore rational fertilizations are important to maintain the production and sustainable development of vegetable. In this study, two fertilization treatments (optimized fertilization and conventional fertilization, noted as OF and CF, respectively) under continuous tomato-pepper cropping were arranged to investigate soil physicochemical properties, abundance and trophic groups of nematode and vegetable yield. The results showed that OF could maintain soil pH at the relatively higher level and increase the yield of tomato and pepper by 9.0% and 6.9% compared to CF treatment. In contrast to CF, OF increased nematode quantity and the relative abundance of bacterivores, but decreased the relative abundance of fungivores and plant-parasites, more obviously in the growth season of tomato. No obvious differences in plant parasite index, diversity, and richness were observed between CF and OF treatments across all sampling stages of tomato and pepper. Nematode channel ratio ranged from 0.39 to 0.64 in CF treatment, which was significantly lower than that in OF treatment (0.67-0.84), suggesting that the decomposition of food network was dominated by fungi in CF treatment but by bacteria in OF treatment. Based on soil physicochemical properties, nematode groups and vegetable yield, we concluded that optimized fertilization could not only increase vegetable growth but also improve soil ecological environment.

Effects of pomegranate varieties on the development and fecundity of Assara inouei Yamanaka (Lepidoptera: Pyralidae)

HE Chao, SHEN Deng-rong, YIN Li-hong, LI Xi-liang, HE Jian-cai, YUAN Sheng-yong, TIAN Xue-jun

2017, 28(3):  935-940.  doi:10.13287/j.1001-9332.201703.009

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Assara inouei Yanmanaka is an important pest of pomegranate fruits in Yunnan Province. To examine the effects of different pomegranate varieties on the development and reproduction of A. inouei, the biological characteristics, such as the developmental duration, the survival rate and reproduction of this pest feeding on five pomegranate varieties including Tianlvzi, Houpitianshazi, Tianguangyan, Suanlvzi and Suanshazi were observed respectively, and the life table parameters were established under the laboratory conditions of (25±1) ℃, RH (70±10)% and a photoperiod of 15 L:9 D. The results showed that there were no significant differences in the egg stage, larval stage, pupal stage, the longevity of male adults, generation duration form egg to adult and egg hatch rate among the five varieties. There were significant differences in the pre-pupal stage, the longevity of female adults, larval survival, pupation, eclosion and total survival rates, the number of eggs laid per female as well as male and female pupal mass among the five varieties, and all of which except the larval survival were higher on Suanlvzi, followed by Houpitianshazi, but there was no significant difference between these two varieties. The results of life table showed the net reproduction rate, the intrinsic rate of increase and finite rate of increase of the Suanlvzi population were the highest. There were no significant differences in the mean generation time among the five varieties, but significant difference was observed in the population doubling time, which was the shortest on Suanlvzi population. The development and reproduction of A. inouei were better on the Suanlvzi and Houpitianshazi among the five varieties.

A banker plant system of ‘Leesia sayanuka-Nlilaparvata muiri-Tytthus chinensis’ to control rice planthoppers

ZHENG Xu-song, TIAN Jun-ce, ZHONG Lie-quan, XU Hong-xing, LYU Zhong-xian

2017, 28(3):  941-946.  doi:10.13287/j.1001-9332.201703.010

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In order to clarify the feasibility of the banker plant system “Leesia sayanuka-Nlilaparvata muiri-Tytthus chinensis” to control rice planthooper, the effects of the combination of rice, L. sa-yanuka, N. lugen and N. muiri on the adult morphology, population growth, oviposition and feeding selectivity of T. chinensis were carried out in the present study. The results showed that the body size of male and female adults of T. chinensis rice population (feeding on N. lugens eggs) were significantly larger than those of T. chinensis population (feeding on N. muiri eggs). Population growth parameters including fecundity, net productive rate, innate capacity for increase, finite rate of increase of L. sayanuka feeding on N. lugens eggs were significantly higher than those of L. sayanuka feeding on N. muiri eggs. However, the population growth ability of L. sayanuka feeding on N. muiri was still high enough to expand the population. For the oviposition selection, both rice population and L. sayanuka population preferred laying eggs on rice than on L. sayanuka. Meanwhile, there was no significant difference in the predation of females, males and nymphs to N. lugens eggs or N. muiri eggs between rice population and L. sayanuka population. At last, based on our results, we discussed the feasibility of establishing the banker plant system “L. sayanuka-N. muiri-T. chinensis” in rice fields.

Genetic diversity and phylogenetic analysis of Fusarium oxysporium strains isolated from the Cucurbitaceae hosts revealed by SRAPs

TIAN Ye-han, HOU Yuan-yuan, PENG Cai-yun, WANG Yong-yang, HE Bang-ling, GAO Ke-xiang

2017, 28(3):  947-956.  doi:10.13287/j.1001-9332.201703.003

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Cucurbitaceae wilt of different hosts could be caused by Fusarium oxysporum. To clear the genetic diversity and phylogenetic relationship of F. oxysporum isolates from different Cucurbitaceae hosts and regions, genomic DNA of ninety-five strains of F. oxysporum isolated from different hosts and different regions were amplified by sequence-related amplified polymorphism (SRAP) molecular markers. All strains could be uniquely distinguished with 238 polymorphism bands which generated 100% of polymorphic ratio with 19 selective primer pairs. On average, each primer pairs amplified 12.5 loci and 12.5 polymorphic loci. A total of 166 bands of F. oxysporum f. sp. momordicae (FOM) were amplified, among which 145 polymorphic bands generated 87.4% of polymorphic ratio. On average, each primer combination amplified 8.7 loci and 7.7 polymorphic loci. This indicated that genetic variation of F. oxysporum was extensive. The genetic similarity coefficient of F. oxysporum was 0.68-0.99, and the average indexes of Nei’s genetic diversity and Shannon were 0.2390 and 0.3718, respectively. Ninety-five strains of F. oxysporum were divided into four formae speciales from bitter gourd, cucumber, watermelon and melon, when the genetic similarity coefficient was 0.74. In SRAP dendrogram all the FOM isolates were gathered into one phylogenetic branch with the genetic similarity coefficient ranging from 0.78 to 0.99. The average indexes of Nei’s genetic diversity and Shannon indices were 0.1811 and 0.2750, respectively. This indicated that genetic diversity of FOM was abundant, and the classification of phylogenetic group was related to geographic origin to some extent.

Effects of legume-oat intercropping on abundance and community structure of soil N₂-fixing bacteria

YANG Ya-dong, FENG Xiao-min, HU Yue-gao, REN Chang-zhong, ZENG Zhao-hai

2017, 28(3):  957-965.  doi:10.13287/j.1001-9332.201703.007

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In this study, real-time PCR and high-throughput sequencing approaches were employed to investigate the abundance and community structure of N₂-fixing bacteria in a field experiment with three planting patterns (Oat monoculture, O; Soybean-oat intercropping, OSO; Mung bean-oat intercropping, OMO). The results showed that soil chemical properties varied significantly in different soil samples (P＜0.05). The abundance of nifH gene varied from 1.75×10¹⁰ to 7.37×10¹⁰ copies·g^-1 dry soil in all soil samples. The copy numbers of nifH gene in OSO and OMO were 2.18, 2.64, and 1.92, 2.57 times as much as that in O at jointing and mature stages, with a significant decline from jointing to mature stage for all treatments (P＜0.05). Rarefaction curve and cove-rage results proved the nifH gene sequencing results were reliable, and the diversity index showed that the N₂-fixing bacteria diversity of OSO was much higher than that of O. Azohydromonas, Azotobacter, Bradyrhizobium, Skermanella and other groups that could not be classified are the dominant genera, with significant differences in proportion of these dominant groups observed among all soil samples (P＜0.05). Venn and PCA analysis indicated that there were greater differences of nifH gene communities between jointing and mature stages; however, the OSO and OMO had similar communities in both stages. All these results confirmed that legume-oat intercropping significantly increased the abundance and changed the community composition of N₂-fixing bacteria in oat soils.

Soil water reservoir properties of green belts in the central urban area of Shanghai, China

WU Hai-bing, ZHOU Jian-qiang, FANG Hai-lan

2017, 28(3):  966-974.  doi:10.13287/j.1001-9332.201703.013

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Taking the typical parks and public green belts in the central urban area of Shanghai for examples, water reservoir storage of soils of different types and influencing factors were investigated based on field surveys. The results showed that the total reservoir capacity of soils of the green belts in the central urban area of Shanghai was relatively low. However, the whole green belts still accumulated a large amount of water, which reached up to 1.88×10⁷ m³. The existing water volume was 75.7% of the total reservoir capacity, while the remaining water storage was relatively low. The detention capacity and the effective storage of green belts were 31.6% and 27.2%, respectively. The dead storage was 44.5 %. Moreover, some difference existed in the water reservoirs for different vegetation types. The total water reservoir capacity of soils and the remaining water-storage space of the tree and brush lands were obviously higher than those of the grass lands. The water-detention capacity and the effective storage of the brush lands were remarkably higher than those of the tree and grass lands, but there was no remarkable difference among various vegetation types for both the existing water volume and the dead water storage. Thus, reducing soil compaction, increasing organic-matter content, improving physical properties and optimizing plant allocation of green belts would improve the water reservoir capacity effectively for the urban green belt soils.

Design of sponge city and its inspiration to landscape ecology: A case of Liaodong Bay area of Panjin City, Northeast China

SUI Jin-ling, LIU Miao, LI Chun-lin, HU Yuan-man, WU Yi-lin, LIU Chong

2017, 28(3):  975-982.  doi:10.13287/j.1001-9332.201703.033

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With the expansion of urban area, many cities are facing urban water environment issues, i.e., water resources shortage, lack of groundwater reserves, water pollution, urban waterlogging. For resolving these urban issues, ‘sponge city’ was proposed in 2015 in China. Liaodong Bay area of Panjin City in Liaoning Province of China was chosen as case study. Based on ‘Sponge City Construction Technology Guide: Low Impact Development Rainwater System Building (Trial)’, the underlying surface and types of land use in the typical area were analyzed. Sponge city plan of the study area was designed through combining topography, hydrology, rainfall intensity and other factors, and selecting LID measures. The results showed that when the study area reached the ove-rall target control rate (the control rate of the total annual runoff was ＞75%), the subsidence greenbelt rate was 1%-31%, with a total area of 13.73 km²; the pervious pavement rate was 1%-13%, with a total area of 2.29 km². This study could provide a case study for planning and designing of ‘sponge city’, proposing new ideas and methods for the research on landscape pattern and process.

Assessing the surface heating effect of the open-path analyzer of an eddy covariance system with fine-wire thermocouples

WANG Xing-chang, WANG Chuan-kuan, LIU Fan, ZHEN Xiao-jie

2017, 28(3):  983-991.  doi:10.13287/j.1001-9332.201703.023

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The open-path CO₂/H₂O analyzer that is currently widely used in the eddy covariance (EC) system possesses a surface heating effect, which may influence the accuracy of the eddy-flux measurements. Taking the open-path EC system in the temperate deciduous forest of the Maoershan Ecosystem Research Station as a case, we assessed the heating effect of the open-path CO₂/H₂O ana-lyzer (Li-7500) with fine-wire thermocouples and tested the applicability of Burba’s equations. The results indicated that between April 23 and May 28 in 2016, the daytime air temperature in the mid-optical-path of the Li-7500 was on average 0.2 ℃ higher than the ambient air temperature, while the nocturnal temperature was almost equal, with the peak of the heating often occurring in the morning transition period and at noon or in the early afternoon. The diurnal variation in the heating effect on the sensible heat flux (H_S,HE) estimated from the simple linear-fitting models in the fourth method by Burba (BurbaLF) was overall a rectangle-like wave, whereas that from the multiple regression models (BurbaMR) showed a weak mono-peak shape. Compared with direct mea-surements (K079) with the K-type fine-wire thermocouples (with a 0.079 mm diameter of single bare wire) and the H_S,HE modeled with two fine-wire thermocouples (K079Model), the estimated H_S,HE with the BurbaLF and BurbaMR varied little in the daytime with a lower but wider daytime-peak (20 W·m^-2), a sharp transition between daytime and nighttime, and a typical nocturnal va-lue of ＜ 5 W·m^-2. The peak values of H_S,HE estimated from the K079 and K079Model could be higher than 40 W·m^-2, and the values at night fluctuated around zero. The sensible heat flux in the optical-path of the Li-7500 was increased by 13.6% during the daytime. The value of the daytime heating effect on the CO₂ turbulent flux (F_c,HC) estimated from the K079 and K079Model was averaged about 0.5 mg CO₂·m^-2·s^-1, twice of the value estimated previously. Compared with the direct measurements, the Burba equations underestimated the F_c,HC around the noon due to the inadequate H_S,HE, but overestimated the F_c,HC in the morning, the late afternoon and the night because of over-corrections of H_S,HE, resulting in an overall overestimate of F_c,HC. These findings validated that both K079 and K079Model methods can be used to estimate the F_c,HC.

Prediction for the potential distribution area of Codonopsis pilosula at global scale based on Maxent model

GUO Jie, LIU Xiao-ping, ZHANG Qin, ZHANG Dong-fang, XIE Cai-xiang, LIU Xia

2017, 28(3):  992-1000.  doi:10.13287/j.1001-9332.201703.026

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Maximum entropy model (Maxent) and geographic information system (GIS) were used to predict the global ecological suitable region of Codonopsis pilosula based on 129 distribution data and 37 ecological factors. The results showed that the total area of ecological suitable region was about 884.79×10⁴ km², mainly in East Asia of the Northern Hemisphere, especially concentrated in China. The ecological suitable region in China with high suitable index was mainly in Shanxi, Shaanxi, Sichuan, southeast of Gansu, east of Tibet, southeast of Yunnan, and the northeast of Shandong. It was indicated that China had the most suitable region for C. pilosula cultivation. The main influence factors for the geographical distribution of C. pilosula were climate factors, and the first factor was temperature, the next one was precipitation, and the topography factors and soil factors followed. Mean annual temperature, precipitation seasonality, mean temperature of coldest quarter and precipitation of driest quarter were the most important factors for the distribution of C. pilosula.

Identification of the long-term patterns of catchment development and diatom community changes in Xihu Lake, Dali, Yunnan, China

KANG Wen-gang, CHEN Guang-jie, WANG Jiao-yuan, HU Kui, TAO Jian-shuang, LIU Yuan-yuan, CHEN Xiao-lin, HUANG Lin-pei, ZHAO Shuai-ying

2017, 28(3):  1001-1012.  doi:10.13287/j.1001-9332.201703.040

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Limnological studies have long focused on the nine largest plateau lakes and ecological assessment of lake eutrophication in Yunnan. However, comprehensive surveys of small and me-dium-sized lakes and their response to multiple stressors are largely absent. Here, we combined multi-proxy sediment analyses and documentary data, aiming to identify the long-term pattern of diatom community changes under the influence of climate change and anthropogenic disturbances, and to quantify their driving strengths. The results showed that Xihu Lake was in a pre-impact state with little ecological variability before the 1950s. Thereafter, expansion of land use increased the nutrient input and altered the lake hydrology, resulting in a significant shift of dominant diatoms from Cocconeis placentula to Fragilaria spp. From 1997, accelerating nutrient enrichment and hydrological changes led to the replacement of benthic diatoms by planktonic ones, resulting in a consistent loss of macrophytes and a decrease of ecological stability. Therefore, the types and strength of catchment development should be fully evaluated for effective protection of small and medium-sized alpine lakes in the context of global warming.

Construction and optimization of ecological network for nature reserves in Fujian Province, China

GU Fan, HUANG Yi-xiong, CHEN Chuan-ming, CHENG Dong-liang, GUO Jia-lei

2017, 28(3):  1013-1020.  doi:10.13287/j.1001-9332.201703.022

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The nature reserve is very important to biodiversity maintenance. However, due to the urbanization, the nature reserve has been fragmented with reduction in area, leading to the loss of species diversity. Establishing ecological network can effectively connect the fragmented habitats and plays an important role in species conversation. In this paper, based on deciding habitat patches and the landscape cost surface in ArcGIS, a minimum cumulative resistance model was used to simulate the potential ecological network of Fujian provincial nature reserves. The connectivity and importance of network were analyzed and evaluated based on comparison of connectivity indices (including the integral index of connectivity and probability of connectivity) and gravity model both before and after the potential ecological network construction. The optimum ecological network optimization measures were proposed. The result demonstrated that woodlands, grasslands and wetlands together made up the important part of the nature reserve ecological network. The habitats with large area had a higher degree of importance in the network. After constructing the network, the connectivity level was significantly improved. Although interaction strength between different patches va-ried greatly, the corridors between patches with large interaction were very important. The research could provide scientific reference and basis for nature protection and planning in Fujian Province.

Delineation of ecological security pattern based on ecological network

FU Qiang, GU Chao-lin

2017, 28(3):  1021-1029.  doi:10.13287/j.1001-9332.201703.018

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Ecological network can be used to describe and assess the relationship between spatial organization of landscapes and species survival under the condition of the habitat fragmentation. Taking Qingdao City as the research area, woodland and wetland ecological networks in 2005 were simulated based on least cost path method, and the ecological networks were classified by their corridors’ cumulative cost value. We made importance distinction of ecological network structure elements such as patches and corridors using betweenness centrality index and correlation length-percentage of importance of omitted patches index, and then created the structure system of ecological network. Considering the effects brought by the newly-added construction land from 2005 to 2013, we proposed the ecological security pattern for construction land change of Qingdao City. The results showed that based on ecological network framework, graph theory based methods could be used to quantify both attributes of specific ecological land (e.g., the area of an ecological network patch) and functional connection between ecological lands. Between 2005 and 2013, large area of wetlands had been destroyed by newly-added construction land, while the role of specific woodland and wetland played in the connection of the whole network had not been considered. The delineation of ecological security pattern based on ecological network could optimize regional ecological basis, provide accurate spatial explicit decision for ecological conservation and restoration, and meanwhile provide scientific and reasonable space guidance for urban spatial expansion.

Reviews

Research progress in effects of biochar application on crop growth and synergistic mechanism of biochar with fertilizer

LIU Yue, LI Zi-han, ZOU Bo, SUN Sheng-yi, GUO Jian-zeng, SUN Cai-xia

2017, 28(3):  1030-1038.  doi:10.13287/j.1001-9332.201703.035

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The application of biochar made from crop straw to soil has already become a research hotspot in the field of agriculture at home and abroad, because it can increase crop production capacity with specific environmental benefits. This review summarized the progress of recent research regarding the molecular mechanisms underlying the effects of biochar on crop growth, with particular emphasis on the interactions between crop roots and biochar in soil. The biological effects of the interactions between fertilizer and biochar application and the probable mechanisms underlying the synergistic effect were discussed. The current work proposed the prospects of biochar in agriculture and would promote the relative researches in China. The recent researches indicated that auxin and related signaling molecules play a key role in the growth stimulation in response to biochar application by promoting the expression of genes controlling cell expansion, loosening of the cell wall, and membrane transport for water and nutrients. Biochar and its interaction with plant roots could directly or indirectly influence the physical, chemical and biological properties of soil, which would regulate the function and synergistic effects of biochar coupled with fertilizer.

A review of air pollutant diffusion models for urban street

ZHOU Shu-wen, TANG Rong-li, ZHANG Yu-xin, MA Ke-ming

2017, 28(3):  1039-1048.  doi:10.13287/j.1001-9332.201703.028

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Street is an important place for urban residents, and the air quality in streets is closely related to residents’ health. Air pollutant diffusion model is an often used measure to simulate and evaluate air quality in street canyon in recent years, but the problems existing in model application need to be clarified. This review selected four air pollutant diffusion models, i.e., ENVI-met, FLUENT, MISKAM and OSPM, which were most popular in street canyon studies. Through comparisons on the model mechanisms, the operational processes, the temporal-spatial resolutions and so on, their differences in model scopes and modeling capabilities in street canyon air quality simulation were discriminated, the model deficiencies were pointed out according to temporal scale, modeling, weather handling, turbulent simulation and photochemical pollution, and several model optimization measures were suggested in terms of street canyon study. Moreover, through reviewing the case stu-dies of the four models, the shortcomings in model application were concluded, and some new techniques were highlighted for future application studies such as laser radar to improve input data accuracy, and the importance of considering urban heat island and urban pollutant island simultaneously was emphasized in evaluating street environment quality.

Research progress in material metabolism and its effects on resource and environment

HAN Ji, ZHOU Yan

2017, 28(3):  1049-1060.  doi:10.13287/j.1001-9332.201703.002

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Studies on the material throughput in the socioeconomic system from the viewpoint of metabolism is not only important for understanding the relationship between human activities and natural environment, but also helpful for utilizing resources in a reasonable and sustainable manner. Based on the review of the research progress in material metabolism worldwide, which included the methodology, application on different scales, and effects on resource and environment, the state of the art of existing literature and the challenges remained for future studies were summarized systema-tically. The material metabolism research should shift its focus on the single theory and method to the integration of multi-theories and methods so as to address the complex metabolism problems. With the increasingly important role that cities play in global ecological environment, more emphasis should be laid on the combination of traditional metabolism research with spatial analysis, and the incorporation of indicators like human wellbeing into the research scope in city-scale research. By doing so, more actionable and sustainable policies could be designed to conserve resources, mitigate the environmental load, and enhance the coordination among the development in economy, environment and society.