Table of Content

18 November 2016, Volume 27 Issue 11

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Response of tree seedlings to altitudinal gradient and its seasonal variation in Ailao Mountain and Yulong Mountain, Yunnan Province, China.

LI Jie-qiong, SONG Xiao-yang, CAO Min

2016, 27(11):  3403-3412.  doi:10.13287/j.1001-9332.201611.017

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Tree seedlings under forests serve as an important part of forest ecosystem and play a role in the natural regeneration of forests. To understand the altitudinal distribution patterns of tree seedlings and the response to seasonal variation, we investigated the species composition and individual numbers of tree seedlings, and their seasonal dynamics in Ailao Mountain (subtropical region) and Yulong Mountain (subalpine region) in Yunnan Province. The results showed that the species richness of tree seedlings increased with altitude, peaked in the middle of the mountains, and followed a decline at higher altitudes, and the dominant species also changed significantly. Species richness of tree seedlings was significantly higher at the end of rainy season than that at the end of dry season, and the dominant species had obvious seasonal difference.

Effect of thinning intensities on fruiting regularities of Quercus liaotungensis forests in Huang-long and Qiaoshan mountains.

HUANG Cai-zhi, ZHANG Wen-hui, LI Gang, YU Shi-chuan, YOU Jian-jian

2016, 27(11):  3413-3419.  doi:10.13287/j.1001-9332.201611.010

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In order to clarify the impact of thinning intensities on fruiting regularity of Quercus liaotungensis forests, we took the Q. liaotungensis half-mature forests in Huanglong and Qiaoshan mountains on south of the Loess Plateau as the object of study, which were under close-to-natural management of different thinning intensities (CK, 10%, 20% and 30%). An analysis was made on stand density and percent of seed trees, seed number of sample tree and unit area, seed spatial distributions, seed characteristics of the Q. liaotungensis forests after 5 years of thinning. The results showed that, percent of seed trees, seed number per sample tree and percent of developed seeds of Q. liaotungensis forests increased with the increasing intensity, and showed a pattern of 30%>20%>10%>CK. Seed number per area reached the maximum number under 20% thinning, and showed a pattern of 20%>30%>CK>10%. From the seed spatial distribution in the canopy, the upper accounted for 73.6%, while the lower had 26.4%. The sunny side of canopy layer set relatively the most fruits of 65.8%, shady side only had 34.2%. Under thinning, further improving was geater under lower canopy than under upper canopy and so was on shady side than on sunny side. The seed long diameter, seed short diameter and 1000-seed mass of Q. liaotungensis forests increased with the increasing intensity, which reached the maximum under 30% thinning. 10% thinning did not significantly impact Q. liaotungensis fruiting, the thinning intensity of 20% was most conducive to the seed quantity and quality improvement of Q. liaotungensis, while the thinning intensity of 30% did not improve the fruiting, and lowered the total number of seeds. It was proposed that 20% thinning should be chosen (canopy density of 0.7) to effectively improve fruiting and quality of Q. liaotungensis.

Maximum density-size line for Larix olgensis plantations based on quantile regression.

GAO Hui-lin, DONG Li-hu, LI Feng-ri

2016, 27(11):  3420-3426.  doi:10.13287/j.1001-9332.201611.026

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Based on 378 permanent and 415 temporary plots from Northeast China, the relationship of maximum stand density and quadratic mean diameter at breast height of treesfor Larix olgensis plantation was developed. Linear quantile regression model with different quantiles (τ=0.90, 0.95, 0.99) was used and the optimal model for the maximum density-size line model was selected. The ordinary least square (OLS) and maximum likelihood (ML) regression were also employed to develop the maximum density-size line by using the arbitrary selected data. Generalized Pareto model of extreme value theory was used to calculate the number of limited maximum trees based on the current stands so that the limited density-size line was developed. The linear quantile regression model was compared with the other methods. The results showed that selecting 5 points within the whole diameter class for the maximum density-size line model development would get the satisfying prediction model. The fitting line would deviate from the maximum density-size line with the increasing points selected. The method of ML was superior to OLS in parameter estimation. The linear quantile regression model with the quantile of 0.99 achieved similar fitting results compared with ML regression and the estimation results was much stable. Traditional approach that selecting fittng data was considered arbitrary so that linear quantile regression with quantile of 0.99 was selected as the best model to construct the maximum density-size line with the estimates for the parameters as k=11.790 and β=-1.586, and k=11.820 and β=-1.594 for the limited density-size line model. The determined limited density-size line was above the maximum density-size line but the difference was not pronounced. The validation results by using the data of permanent sample plots showed the models were suitable to predict the maximum and limited density line of the current forest stands, which would provide basis for the sustainable management of L. olgensis plantation.

Effects of nitrogen additions on soil hydrolase and oxidase activities in Pinus elliottii plantations.

ZHANG Chuang, ZOU Hong-tao, ZHANG Xin-yu, KOU Liang, YANG Yang, SUN Xiao-min, LI Sheng-gong, WANG Hui-min

2016, 27(11):  3427-3434.  doi:10.13287/j.1001-9332.201611.016

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We evaluated responses of hydrolase and oxidase activities in a subtropical Pinus elliottii plantation through a nitrogen (N) addition field experiment (dosage level: 0, 40, 120 kg N·hm^-2·a^-1). The results showed that N additions significantly decreased the carbon, nitrogen and phosphorus related hydrolase and oxidase activities. The activities of β-1,4-glucosidase (BG), cellobiohydrolase (CBH), β-1,4-N-acetylglucosaminidase (NAG) and peroxidase (PER) activities were decreased by 16.5%-51.1% due to N additions, and the decrease was more remarkable in the higher N addition treatment. The activities of α-1,4-glucosidase (aG), β-1,4-xylosidase (BX), acid phosphatase (AP) and phenol oxidase (PPO) were decreased by 14.5%-38.6% by N additions, however, there was no significant difference among the different N addition treatments. Soil enzyme activities varied obviously in different seasons. The activities of BG, NAG, BX, CBH, AP and PPO were in the order of March > June > October, and aG and PER activities were in the order of October > March > June. Most of the soil hydrolase and oxidase activities were positively correlated with soil pH, but negatively with NO₃^--N content. It indicated that N additions inhibited soil hydrolase and oxidase activities by reducing soil pH and increasing soil nitrification. N additions inhibited the soil organic matter mineralization and turnover in the subtropical area, and the effects were obvious with the increasing dosage of N additions.

Response in cuttings of Taxodium hybrid ‘Zhongshanshan’ and their parents to drought and re-hydration.

SHI Qin, YIN Yun-long, WANG Zhi-quan, FAN Wen-cai, HUA Jian-feng

2016, 27(11):  3435-3443.  doi:10.13287/j.1001-9332.201611.024

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In this study, three different strains of Taxodium hybrid ‘Zhongshanshan’ varieties [T. hybrid 302 (T. distichum♀×T. mucronatum♂), T. hybrid 407 (T. mucronatum♀×T. distichum♂), T. hybrid 118 (T. hybrid 302 ♀×T. macronatum ♂)] and their parents, T. distichum and T. mucronatum, were applied to investigate the response of photosynthetic characteristics, antioxidant enzyme systems and morphological characteristics to drought stress and recovery. The results indicated that as drought days were prolonged, all plants’ net photosynthetic rate (P_n) decreased, while proline accumulated. Meanwhile, the antioxidases functioned to eliminate malonaldehyde toxicity. On the 8^th day, the decrease of P_n of T. distichum was the biggest, T. hybrid 118 plants showed the highest water use efficiency and the smallest MDA content, while T. macronatum plants increased the activity of superoxide dismutase and content of proline. After rewatering for 2 days, all these parameters showed signs of recovery, and the T. hybrid 118 plants showed the fastest recovery rate since their P_n and proline content had recovered for 74.4% and 60.2%, respectively. Then after recovered for 9 days, all tested parameters had almost restored to equivalent levels of CK plants. The total biomass of T. hybrid 118 plants was not affected, while the ratio of root to shoot was significantly (P<0.05) increased. The drought-resistance capacity ranged as T. macronatum>T. hybrid 118>T. hybrid 407>T. hybrid 302>T. distichum plants. In conclusion, the backcross generation T. hybrid 118 plants largely inherited the drought resistance of T. mucronatum, and the result would be instrumental in breeding and popularization of drought-resistant hybrid varieties.

Functional diversity characteristics of canopy tree species of Jianfengling tropical montane rainforest on Hainan Island, China.

XU Ge-xi, SHI Zuo-min, TANG Jing-chao, LIU Shun, MA Fan-qiang, XU Han, LIU Shi-rong, LI Yi-de

2016, 27(11):  3444-3454.  doi:10.13287/j.1001-9332.201611.037

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Based on three 1-hm² plots of Jianfengling tropical montane rainforest on Hainan Island, 11 commom used functional traits of canopy trees were measured. After combining with topographical factors and trees census data of these three plots, we compared the impacts of weighted species abundance on two functional dispersion indices, mean pairwise distance (MPD) and mean nearest taxon distance (MNTD), by using single- and multi-dimensional traits, respectively. The relationship between functional richness of the forest canopies and species abundance was analyzed. We used a null model approach to explore the variations in standardized size effects of MPD and MNTD, which were weighted by species abundance and eliminated the influences of species richness diffe-rences among communities, and assessed functional diversity patterns of the forest canopies and their responses to local habitat heterogeneity at community’s level. The results showed that variation in MPD was greatly dependent on the dimensionalities of functional traits as well as species abundance. The correlations between weighted and non-weighted MPD based on different dimensional traits were relatively weak (R=0.359-0.628). On the contrary, functional traits and species abundance had relatively weak effects on MNTD, which brought stronger correlations between weighted and non-weighted MNTD based on different dimensional traits (R=0.746-0.820). Functional dispersion of the forest canopies were generally overestimated when using non-weighted MPD and MNTD. Functional richness of the forest canopies showed an exponential relationship with species abundance (F=128.20; R²=0.632; AIC=97.72; P＜0.001), which might exist a species abundance threshold value. Patterns of functional diversity of the forest canopies based on different dimensional functional traits and their habitat responses showed variations in some degree. Forest canopies in the valley usually had relatively stronger biological competition, and functional diversity was higher than expected functional diversity randomized by null model, which indicated dispersed distribution of functional traits among canopy tree species in this habitat. However, the functional diversity of the forest canopies tended to be close or lower than randomization in the other habitat types, which demonstrated random or clustered distribution of the functional traits among canopy tree species.

Effects of intensive management on soil C and N pools and soil enzyme activities in Moso bamboo plantations.

YANG Meng, LI Yong-fu, LI Yong-chun, XIAO Yong-heng, YUE Tian, JIANG Pei-kun, ZHOU Guo-mo, LIU Juan

2016, 27(11):  3455-3462.  doi:10.13287/j.1001-9332.201611.029

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In order to elucidate the effects of intensive management on soil carbon pool, nitrogen pool, enzyme activities in Moso bamboo (Phyllostachys pubescens) plantations, we collected soil samples from the soil surface (0-20 cm) and subsurface (20-40 cm) layers in the adjacent Moso bamboo plantations with extensive and intensive managements in Sankou Township, Lin’an City, Zhejiang Province. We determined different forms of C, N and soil invertase, urease, catalase and acid phosphatase activities. The results showed that long-term intensive management of Moso bamboo plantations significantly decreased the content and storage of soil organic carbon (SOC), with the SOC storage in the soil surface and subsurface layers decreased by 13.2% and 18.0%, respectively. After 15 years’ intensive management of Masoo bamboo plantations, the contents of soil water soluble carbon (WSOC), hot water soluble carbon (HWSOC), microbial carbon (MBC) and readily oxidizable carbon (ROC) were significantly decreased in the soil surface and subsurface layers. The soil N storage in the soil surface and subsurface layers in intensively managed Moso bamboo plantations increased by 50.8% and 36.6%, respectively. Intensive management significantly increased the contents of nitrate-N (NO₃^--N) and ammonium-N (NH₄⁺-N), but decreased the contents of water-soluble nitrogen (WSON) and microbial biomass nitrogen (MBN). After 15 years’ intensive management of Masoo bamboo plantations, the soil invertase, urease, catalase and acid phosphatase activities in the soil surface layer were significantly decreased, the soil acid phosphatase activity in the soil subsurface layer were significantly decreased, and other enzyme activities in the soil subsurface layer did not change. In conclusion, long-term intensive management led to a significant decline of soil organic carbon storage, soil labile carbon and microbial activity in Moso bamboo plantations. Therefore, we should consider the use of organic fertilizer in the intensive mana-gement process for the sustainable management of Moso bamboo plantations in the future.

Effects of wind speed on drying processes of fuelbeds composed of Mongolian oak broad-leaves.

ZHANG Li-bin, SUN Ping, JIN Sen

2016, 27(11):  3463-3468.  doi:10.13287/j.1001-9332.201611.028

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Water desorption processes of fuel beds with Mongolian oak broad-leaves were observed under conditions with various wind speeds but nearly constant air temperature and humidity. The effects of wind speed on drying coefficients of fuel beds with various moisture contents were analyzed. Three phases of drying process, namely high initial moisture content (>75%) of phase Ⅰ, transition state of phase Ⅱ, and equilibrium phase III could be identified. During phase Ⅰ, water loss rate under higher wind speed was higher than that under lower wind speed. Water loss rate under higher wind speed was lower than that under lower wind speed during phase Ⅱ. During phase Ⅲ, water loss rates under different wind speeds were similar. The wind effects decreased with the decrease of fuel moisture. The drying coefficient of the Mongolian oak broad-leaves fuel beds was affected by wind speed and fuel bed compactness, and the interaction between these two factors. The coefficient increased with wind speed roughly in a monotonic cubic polynomial form.

Estimation of birch forest LAI based on single laser penetration index of airborne LiDAR data.

XING Yan-qiu, HUO Da, YOU Hao-tian, TIAN Xin, JIAO Yi-tao, XIE Jie, YAO Song-tao

2016, 27(11):  3469-3478.  doi:10.13287/j.1001-9332.201611.020

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Forest leaf area index (LAI) is an important indicator to describe the forest canopy structure and growth status of trees. In this paper, the Yigen area of Inner Mongolia was selected as the study area. Taken full account of the differences among different echo types, the LiDAR point cloud data were split into different single lasers. Then, intensity normalization was implemented for LiDAR point cloud data with the range between sensor and target. Based on the normalized intensity data, a new laser penetration index, called single laser beam penetration index (LPI_s), was calculated along with the calculation of traditional LPI. These two laser penetration indexes were used to estimate the forest LAI based on the theoretical model and empirical model on four different sampling scales (5, 10, 15, and 20 m), respectively, which aimed to improve the retrieval accuracy of forest LAI through laser beam splitting. The results showed that the forest LAI estimated from mean LPI_s (LPI_mean) was obviously better than that from traditional LPI. In addition, both of the empirical [R²=0.80, mean absolute deviation (MAD)=0.11] and theoretical models (R²=0.77, MAD=0.16) achieved the best performances with sampling scale of 15 m. The mapping of birch forest LAI for the study area was derived by integrating both the advantages of best empirical and theoretical models.

Spatial-temporal process and characteristics of vegetation recovery after Wenchuan earthquake: A case study in Longxi River basin of Dujiangyan, China.

LI Jing-zhong, CAO Ming-ming, QIU Hai-jun, XUE Bing, HU Sheng, CUI Peng

2016, 27(11):  3479-3486.  doi:10.13287/j.1001-9332.201611.011

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Quantitative evaluation on the vegetation recovery after the earthquake is of great scienti-fic significance for local ecological system rebuilding and regional social-economic sustainable deve-lopment. By taking the Longxi River Basin in Dujiangyan of Sichuan Province as an example, and employing the MODIS-NDVI time-series data, this paper illustrated the dynamic changes of the ve-getation cover rates in Longxi River basin before and after the “5.12” Wenchuan Earthquake by using Landsat data, and then time-space characters of the recovery rates of the damaged vegetation was quantified structurally by referring the factors of river-system and terrain. The results showed that the recovery of impaired vegetation coverage worked well from a holistic point of view, but the response of vegetation coverage to earthquake disaster showed a lagging-phenomenon. The recovery rate of damaged vegetation was significantly correlated to its distance to surrounding river systems, elevation, slope degree, and slope aspect. This finding could provide technical supports for decision-makers to intervene the recovering process after earthquake.

Carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand land.

MA Jian-ye, TONG Xiao-gang, LI Zhan-bin, FU Guang-jun, LI Jiao, Hasier

2016, 27(11):  3487-3494.  doi:10.13287/j.1001-9332.201611.022

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The aim of this study was to investigate the effects of carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand Land, soil samples were collected from quicksand land, semifixed sand and fixed sand lands that were established by the shrub for 20-55 year-old and the arbor for 20-50 year-old at sand control region of Yulin in Northern Shaanxi Province. The dynamics and sequestration rate of soil organic carbon (SOC) associated with sand, silt and clay were measured by physical fractionation method. The results indicated that, compared with quicksand area, the carbon content in total SOC and all soil particle-sized fractions at bothsand-fixing sand forest lands showed a significant increasing trend, and the maximum carbon content was observed in the top layer of soils. From quicksand to fixed sand land with 55-year-old shrub and 50-year-old arbor, the annual sequestration rate of carbon stock in 0-5 cm soil depth was same in silt by 0.05 Mg·hm^-2·a^-1. The increase rate of carbon sequestration in sand was 0.05 and 0.08 Mg·hm^-2·a^-1, and in clay was 0.02 and 0.03 Mg·hm^-2·a^-1 at shrubs and arbors land, respectively. The increase rate of carbon sequestration in 0-20 cm soil layer for all the soil particles was averagely 2.1 times as that of 0-5 cm. At the annual increase rate of carbon, the stock of carbon in sand, silt and clay at the two fixed sand lands were increased by 6.7, 18.1 and 4.4 times after 50-55 year-old reversion of quicksand land to fixed sand. In addition, the average percentages that contributed to accumulation of total SOC by different particles in 0-20 cm soil were in the order of silt carbon (39.7%)≈sand carbon (34.6%) > clay carbon (25.6%). Generally, the soil particle-sized fractions had great carbon sequestration potential during reversion of desertification in Mu Us Sand Land, and the slit and sand were the main fractions for carbon sequestration at both fixed sand lands.

Diurnal variations of grassland evapotranspiration over different periods in the Pailugou basin in the upper reach of the Heihe River, Northwest China.

WANG Zhong-fu, ZHANG Lan-hui, WANG Yi-bo, HE Chan-sheng

2016, 27(11):  3495-3504.  doi:10.13287/j.1001-9332.201611.012

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Evapotranspiration (ET) is an important component of water cycle, but its measurement in high altitude mountainous region is quite difficult, resulting in the poor understanding of the temporal and spatial variations of actual ET in high altitude mountainous region. In this paper, a weighing lysimeter was used to measure the hourly ET in a grassland in the Pailugou basin in the upper reach of the Heihe River, Northwest China. Based on the measured data, diurnal variations of grassland ET over different periods were analyzed. Results indicated that snow and ice sublimation appeared during the freezing period, with a very different diurnal variation pattern compared with other three periods. During the period without sunshine, the amount of snow and ice sublimation was nearly constant. When the highest global radiation and lowest relative humidity appeared in the same period, the amount of snow and ice sublimation increased a little. The early growth period was a period when snow and ice started to melt, during which snowmelt evaporation and soil evaporation occurred at the same time. The growth period had the highest ET rate. Due to continuous rainfall events, maximum and minimum ET values appeared at the same hour. ET in the late growth period mainly came from soil evaporation, producing 3 peaks in diurnal variation, which was different from only one peak in both the early growth period and the growth period.

Effect of biochar addition on soil evaporation.

XU Jian, NIU Wen-quan, ZHANG Ming-zhi, LI Yuan, LYU Wang, LI Kang-yong, ZOU Xiao-yang, LIANG Bo-hui

2016, 27(11):  3505-3513.  doi:10.13287/j.1001-9332.201611.018

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In order to determine the rational amount of biochar application and its effect on soil hydrological processes in arid area, soil column experiments were conducted in the laboratory using three biochar additions (5%, 10% and 15%) and four different biochar types (d<0.25 mm bamboo charcoal, 0.25 mm <d<1 mm bamboo charcoal, d<0.25 mm wood charcoal and 0.25 mm <d<1 mm wood charcoal; d is particle size) to study their impact on the phreatic water recharge, soil water-holding capacity, capillary water upward movement and soil evaporation. The results showed that the addition of biochar could change the phreatic water recharge, soil water-holding capacity, capillary water upward movement and soil evaporation obviously. But the effects were different depending on the type of biochar raw material and the size of particle. The phreatic water recharge increased with the increasing amount of biochar addition. The addition of biochar could obviously enlarge the soil water-holding capacity and promote the capillary water upward movement rate. This effect was greater when using the material of bamboo charcoal compared with using wood charcoal, while biochar with small particle size had greater impact than that with big particle size. The biochar could effectively restrain the soil evaporation at a low addition amount (5%). But it definitely promoted the soil evaporation if the addition amount was very high. In arid area, biochar addition in appropriate amount could improve soil water retention capacity.

Ion distribution, absorption and translocation characteristics of Alhagi sparsifolia in adaptation to saline habitat.

LUO Han-lin, ZENG Fan-jiang, ZHANG Bo, LIU Bo, ZHAO Sheng-long, GAO Huan-huan

2016, 27(11):  3514-3520.  doi:10.13287/j.1001-9332.201611.013

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In order to explore the adaptive capacity of Alhagi sparsifolia to soil salinity (mild, mo-derate, severe saline soil), the distribution, adsorption and translocation characteristics of Na⁺, K⁺, Ca²⁺, Mg²⁺ in different organs of A. sparsifolia, which is a dominant native vegetation in southern edge of Tarim basin, were investigated. The results showed that when grown on a mild and moderate saline soil, Na⁺ distribution in different organs of A. sparsifolia followed the order of stem≈thorn>leaf>root; when grown on a severe saline soil, Na⁺ distribution followed leaf>stem≈thorn>root. The distribution of Ca²⁺ and Mg²⁺ followed leaf >thorn>stem>root. With the increase of soil salt level, Na⁺ content in different organs of A. sparsifolia increased, while K⁺ content in leave decreased; meanwhile the increasing soil salt level significantly decreased the K⁺/Na⁺ ratio in both root and leave, as well as the Ca²⁺/Na⁺ and Mg²⁺/Na⁺ ratios in all organs. The selective transportation coefficients for Ca²⁺-Na⁺ and Mg²⁺-Na⁺ followed order of stem-leaf>stem-thorn>root-stem under saline habitats. Based on the integrated analysis, in order to adapt to salinity habitat, A. sparsifolia could use multiple organs to accumulate Na⁺, depending on soil salt level. Na⁺ could accumulate in stem and thorn at a relative low level, but in leaves at high levels. Besides, Ca²⁺ and Mg²⁺ could be the inorganic osmotic adjustment substances for A. sparsifolia to adapt the saline environment.

Effects of different cultivation practices on composition, carbon and nitrogen distribution of soil aggregates in farmlands.

CHENG Yi, REN Hao, LIU Peng, DONG Shu-ting, ZHANG Ji-wang, ZHAO Bin, LI Geng, LIU Shao-kun

2016, 27(11):  3521-3528.  doi:10.13287/j.1001-9332.201611.036

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The long-term experiments were conducted at two locations with different soil fertility. There were four treatments, including super high-yielding cultivation treatment (SH), high-yielding and high efficiency cultivation treatment (HH), local farmer’s practice (FP), and control (CK), respectively. The field experiments were established to study the effects of different cultivation practices on composition, carbon and nitrogen distribution of tillage layer soil aggregates in different soil fertility, with the aim of proposing technological approaches to enhance soil fertility and achieve the sustainable development of increasing yield and efficiency in wheat-maize ecosystem. The results indicated that compared with treatments in low soil fertility (LSF), same treatments in high soil ferti-lity (HSF) had the higher mean mass diameter and geometric mean diameter, contents of organic carbon and total nitrogen, and lower fractal dimension in dried soil aggregates at soil tillage layer, which was beneficial to the formation and stability of large aggregate. Optimizing application of NPK fertilizers and the application of combined chemical fertilizer with organic fertilizer could increase the diameter of soil aggregate, reduce the fractal dimension of aggregate and promote the formation and stability of large aggregates, and the effect on HSF was greater than that on LSF; also they could improve the content and distribution of organic carbon and total nitrogen in large soil aggregate, the contribution rate to >5 mm aggregate in LSF was greater than in HSF, while the contribution rate to 5-0.5 mm aggregates in HSF was greater than in LSF.

Effects of residue management and fertilizer application mode on soil organic carbon pools in an oasis cotton region.

ZHANG Peng-peng, LIU Yan-jie, PU Xiao-zhen, ZHANG Guo-juan, WANG Jin, ZHANG Wang-feng

2016, 27(11):  3529-3538.  doi:10.13287/j.1001-9332.201611.031

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To reveal the regulation mechanisms of agricultural management practices on soil organic carbon (SOC) pools and provide scientific basis for improving soil productivity and formulating agricultural fixed carbon and reducing discharge measures, we monitored the changes of SOC pools and organic carbon fractions in an oasis cotton field under different residue management and fertilizer application modes. A split-plot experimental design was used with differing residue management including residue incorporation (S) and residue removing (NS) in the main plots and differing fertilizer application modes including no fertilizer (CK), NPK fertilizer (NPK), organic manure (OM) and NPK fertilizer plus organic manure (NPK+OM) in the subplot. The results showed that fertilization and residue incorporation significantly increased SOC pool, soil organic carbon (C_T), labile carbon (C_L), microbial biomass carbon (C_MB), water-soluble organic carbon (C_WS), hot-water-soluble organic carbon (C_HWS), accumulative amount of soil organic carbon mineralization (C_TM) and carbon management index (CMI). The SOC pool was increased by 20.6% by residue incorporation compared to residue removing. SOC pools were increased by 7.8%, 29.5% and 37.7% in NPK, OM and NPK+OM treatments compared to CK, respectively. The contents of C_T, C_L, C_MB, C_WS and C_HWS under different fertilization treatments were shown as NPK+OM>OM>NPK>CK. C_TM was increased by 5.9% by residue incorporation compared to residue removing and C_TM was increased by 32.7%, 59.5% and 97.3% in NPK, OM and NPK+OM treatments compared to CK, respectively. There was a significant correlation between CMI and C_T, C_MB, C_L, C_WS, C_HWS, C_TM, C pool and C sequestration. Therefore, we concluded that CMI is an important index for evaluating the effect of agricultural management practices on soil quality. In order to construct high-standard oasis farmland in arid region and develop cotton production, we should consider adopting reasonable agricultural management practices (i.e. combining residue incorporation with NPK fertilizer plus organic manure), which could increase the content of SOC, organic carbon fractions and soil fertility, promote soil carbon sequestration, and help the efficient use of agricultural resources and sustainable deve-lopment.

Effect of grafting on rhizosphere soil environment and its relationship with disease resistance and yield of pepper.

DUAN Xi, BI Huan-gai, WEI You-ying, LI Ting, WANG Hong-tao, AI Xi-zhen

2016, 27(11):  3539-3547.  doi:10.13287/j.1001-9332.201611.032

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We investigated the effect of grafting on the root rhizosphere soil microorganisms, physical properties, nutrient content, soil-borne disease and yield of pepper, using ‘Weishi’ (WS) and ‘Buyeding’ (BYD) as rootstocks, the cultivar pepper ‘Xinfeng 2’ (XF) as scion, and the own-root (XF/XF) pepper as the control. The results indicated that XF/WS and XF/BYD significantly increased the populations of fungi and actinomycetes and the percentage of actinomycetes. 60 days after transplanting, the activities of catalase (CAT) and peroxidase (POD) were much higher in root rhizosphere soil of grafted pepper. 90 days after transplanting, the activities of phosphatase, invertase, urease, and nitrate reductase (NR) were much higher in root rhizosphere soil of XF/WS. In addition, The XF/WS and XF/BYD also highly increased hydrocarbon compounds in soil extraction, slightly increased electric conductivity (EC) but lowered nitrogen, phosphorus and potassium contents in root rhizosphere soil. Higher pH in root rhizosphere soil was found in XF/WS but not in XF/BYD. These data indicated that grafting could optimize the rhizosphere soil environment of pepper and enhance the resistance of soil-borne diseases. The yields of XF/WS and XF/BYD were increased by 40.8% and 28.7%, respectively.

Effects of maize and pea intercropping on the total grain yield of community under different planting densities.

GAO Hui, ZHU Qian, ZHANG Rong, MO Tian-lu

2016, 27(11):  3548-3558.  doi:10.13287/j.1001-9332.201611.034

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Under plastic-film fully-mulched ridge-furrow cropping, we studied the effects of within-row-intercropping on total grain yield of community using pea plants inserted into the maize rows with spacing of 40, 50 and 60 cm, respectively, in the Loess Plateau in 2014 and 2015. The result showed that there was significant increase in total grain yield of the community when two pea plants were inserted into the maize rows with spacing of both 40 and 50 cm, while pea plants inserted into the maize row with 60 cm spacing had no significant effects on total grain yield of the community compared to maize monoculture with the same plant spacing in 2014. In 2015, in contrast, when pea plants were inserted into the maize rows with plant spacing of 40 and 50 cm, no significant effect was observed even though there was an increasing trend in total grain yield of the community, while it increased significantly when two pea plants were inserted into the rows with spacing of 60 cm. The more abundant rainfall in 2014 than in 2015 induced the varied effects of intercropping pea plants on increasing the total grain yield of the community between the two cropping seasons. Gene-rally, the total grain yield of the community reached the highest under two pea plants intercropped with spacing of 40 cm. No matter whether in monocultures only with maize or in intercropping with both maize and peas, grain yield decreased significantly with increase of maize plant spacing in current experiment.

Effects of different baynyardgrass varieties on grain yield formation of rice at different nitrogen application levels.

ZHANG Zi-chang, GU Tao, LI Yong-feng, YANG Xia

2016, 27(11):  3559-3568.  doi:10.13287/j.1001-9332.201611.015

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This study aimed to investigate the effects of different barnyardgrass varieties on yield formation of rice. A Japonica rice cultivar, Nanjing 9108, was used and co-cultured with three barnyardgrass varieties from transplanting to maturity under different nitrogen (N) levels of 0, 120, 240, and 360 kg N·hm^-2, taking baynyardgrass free as control. The three barnyardgrass varieties were Echinochloa crusgalli var. mitis, E. crusgali var. zelayensis and E. colonum. The results showed that, at the same N level, the plant height of the three barnyardgrass varieties was E. crusgali var. zelayensis > E. crusgalli var. mitis > E. colonum, and the growth duration was E. crusgalli var. mitis > E. crusgali var. zelayensis > E. colonum. The biomass of baynyardgrass increased with the increase of N application rates and reached a peak at the N rate of 240 kg N·hm^-2, and it decreased at 360 kg N·hm^-2. The biomass of either E. crusgalli var. mitis or E. crusgali var. zelayensis was significantly higher than that of E. colonum. At the 0 kg N· hm^-2 level, all barnyardgrass varieties showed no significant effect on rice yield. At the 120 kg N· hm^-2 level, rice yield was not significantly different among the three treatments of barnyardgrass free, co-cultured with E. crusgalli var. mitis, and co-cultured with E. colonum, but it was significantly decreased when co-cultured with E. crusgali var. zelayensis. At the 240 kg N·hm^-2 level, all treatments of co-cultured with barnyardgrass significantly decreased the rice yield. At the 360 kg N·hm^-2 level, rice yield was significantly decreased under the treatments of co-cultured with E. crusgali var. zelayensis or with E. crusgalli var. mitis, and showed no significant difference between barnyardgrass free and co-cultured with E. colonum. All these data indicated an interaction between barnyardgrass and N fertilizer, which mediated the formation of grain yield of rice. Furthermore, at the 120 kg N· hm^-2 level, the co-cultured E. crusgali var. zelayensis treatment significantly reduced leaf nitrate reductase activity and photosynthetic rate and root oxidation activity during the grain filling period, and decreased nitrogen accumulation and dry matter accumulation at the maturity stage, but other two treatments showed no significant effect when compared with barnyardgrass free treatment. These physiological indices of rice were significantly reduced by both E. crusgalli var. mitis and E. crusgali var. zelayensis treatments at either 240 or 360 kg N·hm^-2 level, and showed no significant difference among all treatments at the 0 kg N·hm^-2 level. Regression analysis showed that the order of effects of barnyardgrass phenotypes on rice grain yield was biomass, plant height, growth duration and tiller number. All these results suggested that the coexistence with large biomass of barnyardgrass inhibited the leaf photosynthetic rate, nitrate reductase activity, root oxidation activity, nitrogen accumulation and dry matter accumulation of rice, and consequently, reduced the rice grain yield.

Effects of potassium on nitrogen translocation and distribution and nitrogen metabolism enzyme activities of sweet potato.

WANG Shun-yi, LIU Qing, SHI Yan-xi, LI Huan

2016, 27(11):  3569-3576.  doi:10.13287/j.1001-9332.201611.021

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A pot experiment with ¹⁵N tracing techniques was designed to study the effect of potassium application on nitrogen transfer, photosynthetic characteristics and nitrogen metabolism enzyme activities in two different growth stages of sweet potato. Results indicated that potassium application significantly increased the shoot ¹⁵N distribution rate. Compared with control, the ¹⁵N transfer rate of K₃ treatment increased by 76.2% and the total accumulation of ¹⁵N increased by 92.1% in tuber formation period. Different with tuber formation period, shoot ¹⁵N distribution rate decreased from 33.7% to 24.4%, but the root ¹⁵N distribution rate increased from 5.8% to 17% with the increase of K application in tuber rapid growth stage. Especially, root ¹⁵N accumulation of K₃ treatment was 3 times of the CK. During the two growth stages, nitrate reductase, glutamate dehydrogenase, glutamine synthetase, glutamate synthase and net photosynthetic rate all increased with the increase of K application. Stepwise regression analysis showed that nitrogen metabolism enzyme activities (nitrate reductase, glutamate dehydrogenase, glutamine synthetase, glutamate synthase) and P_n were the main factors to affect the ¹⁵N transfer and distribution of sweet potato (R₁=0.965,R₂=0.942). Path analysis showed that nitrate reductase and glutamate dehydrogenase activities were the key factors to influence ¹⁵N distribution to the shoot in tuber formation period, while glutamate dehydrogenase, glutamate synthase activities were the key factors to influence ¹⁵N distribution to the tuber in tuber rapid growth stage.

Effects of light quality on growth, secondary metabolites, and oxidative stress tolerance of Gynura bicolor.

GONG Biao, JIN Zhi-yong, LIU Na, LIU Shi-qi, WANG Xiu-feng, AI Xi-zhen, WEI Min, SHI Qing-hua

2016, 27(11):  3577-3584.  doi:10.13287/j.1001-9332.201611.039

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The effects of white light, red light, blue light, yellow light, red+blue light and red+blue+yellow light on the growth and quality of Gynura bicolor were investigated under the same light intensity (350±5 μmol·m^-2·s^-1) by using light-emitting-diodes (LEDs) which could accurately regulate light quality and light intensity. The results indicated that compared with white light, red light could significantly promote the growth of G. bicolor and induce the accumulation of dry substance and soluble sugar content, but blue light inhibited the plant growth. The content of chlorophyll significantly decreased under the colored LEDs. Although the combination of red, blue and yellow light did not increase the dry substance accumulation, it resulted in significant elevation of total phenols, flavonoids and anthocyanins. The accumulation of these reduced substances could increase the tolerance to oxidative stress and the nutrient value in G. bicolor. This study provided a theoretical basis for G. bicolor diverse production regulated by light quality.

Suitability of four stomatal conductance models in agro-pastoral ecotone in North China: A case study for potato and oil sunflower.

HUANG Ming-xia, WANG Jing, TANG Jian-zhao, YU Qiang, ZHANG Jun, XUE Qing-yu, CHANG Qing, TAN Mei-xiu

2016, 27(11):  3585-3592.  doi:10.13287/j.1001-9332.201611.033

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The suitability of four popular empirical and semi-empirical stomatal conductance models (Jarvis model, Ball-Berry model, Leuning model and Medlyn model) was evaluated based on para-llel observation data of leaf stomatal conductance, leaf net photosynthetic rate and meteorological factors during the vigorous growing period of potato and oil sunflower at Wuchuan experimental station in agro-pastoral ecotone in North China. It was found that there was a significant linear relationship between leaf stomatal conductance and leaf net photosynthetic rate for potato, whereas the linear relationship appeared weaker for oil sunflower. The results of model evaluation showed that Ball-Berry model performed best in simulating leaf stomatal conductance of potato, followed by Leuning model and Medlyn model, while Jarvis model was the last in the performance rating. The root-mean-square error (RMSE) was 0.0331, 0.0371, 0.0456 and 0.0794 mol·m^-2·s^-1, the normalized root-mean-square error (NRMSE) was 26.8%, 30.0%, 36.9% and 64.3%, and R-squared (R²) was 0.96, 0.61, 0.91 and 0.88 between simulated and observed leaf stomatal conductance of potato for Ball-Berry model, Leuning model, Medlyn model and Jarvis model, respectively. For leaf stomatal conductance of oil sunflower, Jarvis model performed slightly better than Leuning model, Ball-Berry model and Medlyn model. RMSE was 0.2221, 0.2534, 0.2547 and 0.2758 mol·m^-2·s^-1, NRMSE was 40.3%, 46.0%, 46.2% and 50.1%, and R² was 0.38, 0.22, 0.23 and 0.20 between simulated and observed leaf stomatal conductance of oil sunflower for Jarvis model, Leuning model, Ball-Berry model and Medlyn model, respectively. The path analysis was conducted to identify effects of specific meteorological factors on leaf stomatal conductance. The diurnal variation of leaf stomatal conductance was principally affected by vapour pressure saturation deficit for both potato and oil sunflower. The model evaluation suggested that the stomatal conductance models for oil sunflower are to be improved in further research.

Effects of reducing N, straw returning and dicyandiamide application on winter wheat yield and nitrogen budgets in rain-fed region.

YIN Min Htun, TONG Yan-an, HAN Wen-she, HU Teng, GAO Peng-cheng

2016, 27(11):  3593-3599.  doi:10.13287/j.1001-9332.201611.038

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In a 3-year field experiment, effects of reducing N fertilizer, straw returning and dicyandiamide (DCD) application on wheat yield and nitrogen budgets under wheat-fallow system were studied in rain-fed region. The experiment was carried out in Yangling of Shaanxi Province, and 4 treatments were installed including no nitrogen (CK), 220 kg N·hm^-2 and no straw returning (FP), 150 kg N·hm^-2 and straw returning (OPT), 150 kg N·hm^-2, 7.5 kg·hm^-2 DCD and straw returning (OPT+DCD). The results showed there was no remarkable difference for wheat yield between OPT and FP, but the N use efficiency of the former was 6.1% more than that of the latter, and the apparent N loss ratio was 7.2% less. OPT+DCD increased the average yield of winter wheat by 10.4% and 7.9% respectively compared to OPT and FP, the N use efficiency of winter wheat increased by 20.8% and 28.1%, and the apparent N loss ratio decreased by 8.5% and 15.1%, respectively. NH₄⁺-N content in 0-20 cm of soil increased, accordingly the NO₃^--N content decreased in 40 to 45 days when DCD was applied.

Effects of temperature on leaf lettuce vernalization.

ZHANG Li-li, HAO Jing-hong, HAN Ying-yan, LIU Chao-jie, SU He-nan, LI Pan-pan, SUN Yan-chuan, FAN Shuang-xi

2016, 27(11):  3600-3606.  doi:10.13287/j.1001-9332.201611.014

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To investigate the effects of different temperatures on the vernalization of leaf lettuce, and declare their type, two easy bolting leaf lettuce varieties of GB-30 and GB-31 were selected as material, which were treated by 4 ℃, 20 ℃ and 25 ℃ for 20 d respectively and afterwards treated by high temperature stress. The process of flower bud differentiation was observed by using paraffin section technology, and combined the condition of bolting and flowering to estimate whether or not it underwent vernalization, and defined its vernalization type. The results showed that, two varieties of GB-30 and GB-31 appeared bolting to different degrees at the 8^th day under high temperature stress after temperature treatments in the early stage. Different temperatures in the early stage all made flower bud differentiated of two varieties. 4 ℃ treatment did not advance the flower bud differentiation, while the high temperature in later time accelerated this progress. Furthermore, the days required for the two varieties to complete development stages differed under different temperature treatments. The effective accumulated temperature whether from pregermination to flowering or from high temperature stress to flowering of two varieties were also different. The leaf lettuce without low temperature treatment in early stage could enter into the flower bud differentiation, bolting, budding and flowering stages, and it could be considered as non-low temperature vernalization plant. The high temperature treatment in later stage could obviously promote its bolting and flowering. In addition, the effective accumulated temperature had to reach about 2500 ℃·d from germination to blossom.

Potential distribution of Panax ginseng and its predicted responses to climate change.

ZHAO Ze-fang, WEI Hai-yan, GUO Yan-long, GU Wei

2016, 27(11):  3607-3615.  doi:10.13287/j.1001-9332.201611.040

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This study utilized Panax ginseng as the research object. Based on BioMod2 platform, with species presence data and 22 climatic variables, the potential geographic distribution of P. ginseng under the current conditions in northeast China was simulated with ten species distribution model. And then with the receiver-operating characteristic curve (ROC) as weights, we build an ensemble model, which integrated the results of 10 models, using the ensemble model, the future distributions of P. ginseng were also projected for the periods 2050s and 2070s under the climate change scenarios of RCP 8.5, RCP 6, RCP 4.5 and RCP 2.6 emission scenarios described in the Special Report on Emissions Scenarios (SRES) of IPCC (Intergovernmental Panel on Climate Change). The results showed that for the entire region of study area, under the present climatic conditions, 10.4% of the areas were identified as suitable habitats, which were mainly located in northeast Changbai Mountains area and the southeastern region of the Xiaoxing’an Mountains. The model simulations indicated that the suitable habitats would have a relatively significant change under the different climate change scenarios, and generally the range of suitable habitats would be a certain degree of decrease. Meanwhile, the goodness-of-fit, predicted ranges, and weights of explanatory variables was various for each model. And according to the goodness-of-fit, Maxent had the highest model performance, and GAM, RF and ANN were followed, while SRE had the lowest prediction accuracy. In this study we established an ensemble model, which could improve the accuracy of the existing species distribution models, and optimization of species distribution prediction results.

Allelopathic effects of phenolic compounds of ginseng root rhizosphere on Cylindrocarpon destructans.

LI Zi-bo, ZHOU Ru-jun, XIE Yu-jiao, FU Jun-fan

2016, 27(11):  3616-3622.  doi:10.13287/j.1001-9332.201611.002

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In this study, five phenolic compounds of ginseng rhizosphere soil were identified by HPLC, including gallic acid, salicylic acid, 3-phenylpropionic acid, benzoic acid and cinnamic acid. The results show that five phenolic compounds inhibited mycelium growth and spore germination at high concentration, but promoted mycelium growth and spore germination at low concentration. Gallic acid, salicylic acid, benzoic acid of 0.5 mmol·L^-1 and 3-phenylpropionic acid, cinnamic acid of 0.05 mmol·L^-1 could significantly promote the spore germination, mycelium growth and disease severity of Cylindrocarpon destructans.

Effects of different amendments on contents of phenolic acids and specific microbes in rhizosphere of Pseudostellaria heterophylla.

WU Lin-kun, WU Hong-miao, ZHU Quan, CHEN Jun, WANG Juan-ying, WU Yan-hong, LIN Sheng, LIN Wen-xiong

2016, 27(11):  3623-3630.  doi:10.13287/j.1001-9332.201611.004

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Pseudostellaria heterophylla is a perennial herbaceous plant in the family Caryophyllaceae. The tuberous roots of P. heterophylla are highly valued in traditional Chinese medicine and have a high market demand. However, extended monoculture of P. heterophylla results in a significant decline in the biomass and quality, and escalates disease and pest problems. Therefore, it is important to understand the underlying mechanism and biocontrol methods for consecutive monoculture problems. With “Zheshen 2” as an experimental material, the changes in the contents of main nutrients in soil, phenolic acids and specific microbes under monoculture and different amendments were analyzed by using high performance liquid chromatography (HPLC) and qPCR. The results showed that consecutive monoculture of P. heterophylla led to a decrease in yield by 43.5% while the microbial fertilizer treatment and the paddy-upland rotation could relieve the consecutive monoculture problems. Available nitrogen, available phosphorus, available potassium and total potassium were significantly higher in the consecutively monocultured soils than in the newly planted soils. But consecutive monoculture resulted in soil acidification. HPLC analysis showed that conse-cutive monoculture of this plant did not lead to a consistent accumulation of soil phenolic acids. At middle stage of root expansion and at harvest stage, most of phenolic acids were even higher in the newly planted soils than in the consecutively monocultured soils. Furthermore, qPCR analysis showed that the amounts of three specific pathogens identified previously (i.e. Fusarium oxysporum, Talaromyces helicus, Kosakonia sacchari) were significantly higher in the consecutively monocultured soils than in the newly planted soils. However, the microbial fertilizer treatment and the paddy-upland rotation resulted in a significant decline in the population of these specific pathogens and improved the soil environment. In conclusion, the consecutive monoculture problems of P. heterophylla may be due to the rapid proliferation of host-specific pathogens, rather than the deficiency of soil nutrients and the autotoxicity of allelochemicals in root exudates. The results in this study could provide the theoretical basis to explore the underlying mechanism of replanting disease of P. heterophylla and its biocontrol strategies.

Assessment on heat island effect based on urban regulatory planning.

YUE Wen-ze, LIU Xue

2016, 27(11):  3631-3640.  doi:10.13287/j.1001-9332.201611.019

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With the improved legal status of urban planning, regulatory detailed planning is playing an increasingly important role in guiding land leasing and regulating the spatial structure of urban construction. Understanding the effect of regulatory planning indices on urban heat island (UHI) and evaluating the heat environment performance of indices combination at the scale of regulatory planning unit and plot are of great significance for assessing the thermal environment effect of regulatory planning quantitatively and putting forward action plans to mitigate heat island impacts. In this study, we assessed impacts of main urban regulation indices and their combinations on UHI by analyzing land surface temperature (LST) data, retrieved through the thermal infrared remote sensing image (Landsat8 TIRS), using statistical and GIS spatial analysis methods. Results indicated that the indices of green ratio, plot area, building density and building height all had a significant impact on LST at regulatory planning unit level. By generating 3D models, we found the regulation index combination with round 30% of green ratio, and 2.5-3.5 of floor area ratio had the minimal impact on urban thermal environment at regulatory plot. The outcomes provided a new perspective on the rational improvement of urban regulatory planning.

Evaluation on spatial structure and rationality of city parks based on goal of disaster prevention: An application of proximal area method in Changchun, China.

LI Xiao-ling, XIU Chun-liang, CHENG Lin, WANG Nyu-ying

2016, 27(11):  3641-3648.  doi:10.13287/j.1001-9332.201611.008

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Urban shelter parks as one of the important urban elements are a main form of emergency shelters for a city. This study evaluated the spatial distribution of urban parks in Changchun City with the proximal area method based on disaster prevention goal. Results showed that the spatial distribution of urban shelter parks was unbalanced, with high concentration in the northwest and low concentration in the southeast. The spatial distribution of urban shelter parks of the same grade was concentrated, but the different grades were scattered. The validity of urban shelter parks was low. More than 50% of the park’s per capita refuge area was insufficient. For nearly 40% of the parks, their accessibility was longer than the longest evacuation time. There were significant differences in effectiveness for urban parks of different grades. The urban shelter parks for central disaster prevention were the best, followed by the designated urban shelter parks, whereas urban shelter parks for emergency disaster prevention were the least effective. In view of the layout unreasonable situation of disaster prevention parks in Changchun City, we made following recommendations: the spatial distribution of nesting urban shelter parks with different grades should be used; standards set for urban shelter parks should evolve with population; and the construction of urban shelter parks for emergency disaster prevention should be strengthened.

Change and prediction of the land use/cover in Ebinur Lake Wetland Nature Reserve based on CA-Markov model.

JING Yun-qing, ZHANG Fei, ZHANG Yue

2016, 27(11):  3649-3658.  doi:10.13287/j.1001-9332.201611.027

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Taking Ebinur Lake Wetland Nature Reserve as the study area, and based on the classified result of Landsat TM images of 1998, 2006, and Landsat OLI images of 2014, this paper simulated and forecasted land use/cover types of Ebinur Lake Wetland Nature Reserve by using the CA-Markov model. In the model-building process, the transition probability matrix and the transition area matrix were obtained through the Markov model, which determined the conversion rules and iterative times of the CA model. The land use/cover pattern of the study area in 2014, 2022 and 2030 was simulated and forecasted with the CA-Markov model. Then the forecast result was compared with the actual classified data of 2014 to verify the forecast accuracy. The prediction error of land use/cover type area was not more than 6.4% in 2014, and the spatial location accuracy was 76.0%. The results showed that the forest and grassland, saline-alkali area, dry lake bed and desert had an increasing trend in 1998-2014. The saline-alkali area increased the most by 37.4% and the water body decreased by 34.8%. In 2014-2030, the areas of the forest and grassland, saline-alkali soil and desert would increase, while that of the dry lake bed, water body and other objects would decrease. This study could provide a basis for dynamic monitoring land use/cover as well as sustainable development of Ebinur Lake Wetland Nature Reserve.

Characteristics of rainfall and runoff in urban drainage based on the SWMM model.

XIONG Li-jun, HUANG Fei, XU Zu-xin, LI Huai-zheng, GONG Ling-ling, DONG Meng-ke

2016, 27(11):  3659-3666.  doi:10.13287/j.1001-9332.201611.030

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The characteristics of 235 rainfall and surface runoff events, from 2009 to 2011 in a typical urban drainage area in Shanghai were analyzed by using SWMM model. The results showed that the rainfall events in the region with high occurrence frequency were characterized by small rainfall amount and low intensity. The most probably occurred rainfall had total amount less than 10 mm, or mean intensity less than 5 mm·h^-1,or peak intensity less than 10 mm·h^-1, accounting for 66.4%, 88.8% and 79.6% of the total rainfall events, respectively. The study was of great significance to apply low-impact development to reduce runoff and non-point source pollution under condition of less rainfall amount or low mean rainfall intensity in the area. The runoff generally increased with the increase of rainfall. The threshold of regional occurring runoff was controlled by not only rainfall amount, but also mean rainfall intensity and rainfall duration. In general, there was no surface runoff when the rainfall amount was less than 2 mm. When the rainfall amount was between 2 to 4 mm and the mean rainfall intensity was below 1.6 mm·h^-1, the runoff was less than 1 mm. When the rainfall exceeded 4 mm and the mean rainfall intensity was larger than 1.6 mm·h^-1, the runoff would occur generally. Based on the results of the SWMM simulation, three regression equations that were applicable to regional runoff amount and rainfall factors were established. The adjustment R² of the three equations were greater than 0.97. This indicated that the equations could reflect well the relationship between runoff and rainfall variables. The results provided the basis of calculations to plan low impact development and better reduce overflow pollution in local drainage area. It also could serve as a useful reference for runoff study in similar drainage areas.

Effect of Bt rice straw returning in soil on the growth and reproduction of Eisenia fetida.

CHENG Miao-miao, SHU Ying-hua, WANG Jian-wu

2016, 27(11):  3667-3674.  doi:10.13287/j.1001-9332.201611.009

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Bacillus thuringiensis (Bt) protein can enter the soil through Bt crops straw returning to field, which may affect the growth and reproduction of soil animals, such as earthworms. Here, Bt rice (b2B138) and conventional rice (Anfeng A) straw were returned in soil to evaluate the impact of Bt rice on Eisenia fetida. Two varieties of rice straw were added into soil to breed E. fetida at the rates of 2.5%, 5%, 7.5% and 10%. The survival rate, relative growth rate, reproduction of earthworm, the Cry1Ab content in soil-straw mixture and earthworm were detected after 7, 15, 30, 45, 60, 75, 90 d. The results showed that Bt rice straw returning at higher concentrations (7.5% and 10%) inhibited the survival rate of E. fetida. Bt rice straw returning had no adverse effect on relative growth rate (RGR) of E. fetida. Bt rice straw treatment improved the reproduction of earthworms under 5%, 7.5% and 10% straw returning in soil. Enzyme-linked immunosorbent assay (ELISA) results indicated that immunoreactive Cry1Ab was detectable in soil-straw mixture and E. fetida from Bt rice treatments, and a strong decline was observed in soil-straw mixture with the increase of treated time. Therefore, Cry1Ab released from Bt rice straw returning at 2.5% and 5% concentration had no adverse effects on the growth and reproduction of E. fetida.

Ecological fitness of transgenic GAFP cotton and its effects on the field insect community.

LUO Jun-yu, ZHANG Shuai, ZHU Xiang-zhen, LU Li-min, WANG Chun-yi, LI Chun-hua, ZHANG Li-juan, WANG Li, CUI Jin-jie

2016, 27(11):  3675-3681.  doi:10.13287/j.1001-9332.201611.005

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The ecological fitness of transgenic cotton and its effects on the insect communities in cotton fields is one of the key aspects of the evaluation of the environmental safety of transgenic cotton. New transgenic GAFP (Gastrodia anti-fungal protein) cotton and its parental varieties were used in this study to explore their ecological fitness and their effects on insect community infield in Anyang, Henan Province in 2013 and 2014. The results showed that there was no significant difference in dry mass for transgenic cotton leaves compared to that of parental cotton. Specific leaf areas of transgenic cotton were lowered obviously at seedling stage, while enhanced significantly at budding, flowering and bolling stages relative to parental cotton. The plant height of transgenic cotton was lowered only at seedling stage, and no significant difference was showed between the two cultivars at budding, flowering and bolling stages. No significant differences were discovered on plant branch numbers, bud numbers and falling numbers between the transgenic cotton and control material in any of the four key stages during the cotton growth. However, the number of bolls per plant for transgenic cotton was lower than that of the control cotton at the bolling stage. In the 2nd, 3rd, and 4th generation of cotton bollworm (Helicoverpa armigera), the mortality rate of cotton bollworm and beet armyworm (Spodoptera exigua) of transgenic cotton had no significant difference with parental cotton. Compared to parental cotton, total individuals of insect community, pest sub-communities and enemy sub-communities in transgenic cotton field didn’t show any significant difference. The above results showed that after the GAFP gene was imported into cotton, the cotton growth was enhanced significantly, while the whole yield component traits and the insect community in the field were not significantly changed. Our study on the competition of new transgenic cotton and survival of transgenic cotton insect communities in cotton field would provide the theoretical basis for the evaluation of new transgenic cotton and environmental safety, and accumulate scientific data for environmental safety evaluation of the transgenic cotton.

Effects of increased precipitation and nitrogen deposition on ground-active arthropods in an old-field of Huanghuaihai Plain.

SONG Min

2016, 27(11):  3682-3688.  doi:10.13287/j.1001-9332.201611.035

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As the important driving factors of global change, changing precipitation and nitrogen (N) deposition play a key role in affecting our terrestrial ecosystem. However, most previous stu-dies focused on the aboveground plant community. The soil fauna, especially the ground-active arthropods were poorly understood. Using field manipulative experiment, this paper studied the effects of increased precipitation and N deposition on the soil ground-active arthropods in an old-field ecosystem of the Huanghuihai Plain. The results showed that the increased precipitation significantly enhanced the soil arthropods population density and the number of groups by 66.9% and 27.8%, respectively. Nitrogen deposition had minor effect on soil arthropods population density and number of groups, but significantly increased the formicidae and decreased the collembolans. Our results indicated the changing precipitation was the more important factor than the N deposition to restructure the soil surface arthropod community by increasing soil moisture and stimulating plant growth in the old-field of north China plain.

Contribution of soil fauna to litter decomposition of Abies faxoniana and Rhododendron lapponicum across an alpine timberline ecotone in Western Sichuan, China.

WANG Li-feng, HE Run-lian, YANG Lin, CHEN Ya-mei, LIU Yang, ZHANG Jian

2016, 27(11):  3689-3697.  doi:10.13287/j.1001-9332.201611.025

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Soil fauna is an important biological factor in regulation litter decomposition. In order to quantify the contributions of soil fauna to the mass losses of litter of two dominant species fir (Abies faxoniana) and rhododendron (Rhododendron lapponicum) in the alpine timberline ecotone (coniferous forest-timberline-alpine meadow) of western Sichuan, China, a field litterbag experiment was conducted from May 2013 to November 2014. Samples of air-dried leaf litter were placed in nylon litterbags of two different mesh sizes, i.e. 3.00 mm (with the soil animals) and 0.04 mm (excluded the soil animals). The results showed that the decomposition rate of A. faxoniana (k: 0.209-0.243) was higher than that of R. lapponicum (k: 0.173-0.189) across the timberline ecotone. Soil fauna had significant contributions to litter decomposition of two species, the contributions of soil fauna to mass loss showed a decreasing trend with increasing altitude. From the coniferous forest to the alpine meadow, the mass losses caused by soil fauna for the fir litter accounted for 15.2%, 13.2% and 9.8%, respectively and that for the rhododendron litter accounted for 20.1%, 17.5% and 12.4%, respectively. Meanwhile, the daily average contributions caused by soil fauna for the fir and rhododendron litter decomposition accounted for 0.17%, 0.13%, 0.12% and 0.26%, 0.25%, 0.23%, respectively. Relatively, soil fauna had more influence on alpine rhododendron decomposition. Two-way ANOVA showed that species, altitude and their interaction had significant impact on the litter mass loss and decomposition rate caused by soil fauna. The daily average contribution caused by soil fauna for the fir and rhododendron litter decomposition accounted for 0.25% and 0.44% in the first growing season, then 0.10% and 0.19% in the second growing season, both were higher than that of snow-covered season (0.07% and 0.12%). Regression analysis showed that the environmental factors (daily average temperature, freezing and thawing cycles and snow thickness) explained 42.7% and 50.9% in the mass loss as well as 43.2% and 55.6% in the contribution rate of fir and rhododendron litter decomposition. These results suggest that soil fauna contributes strongly to litter decomposition in the alpine ecosystem, and it is of great significance to thorough understanding and recognizing material cycle through the role of soil fauna in the litter decomposition.

Sublethal effects of spinetoram and azadirachtin on development and reproduction of Frankliniella occidentalis (Pergande).

YANG Guang-ming, ZHI Jun-rui, LI Shun-xin, LIU Li

2016, 27(11):  3698-3704.  doi:10.13287/j.1001-9332.201611.007

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To evaluate the sublethal effects of spinetoram and azadirachtin on western flower thrips, Frankliniella occidentalis, leaf dipping method was used to determine their sublethal concentrations (LC₂₅) on the 2^nd instar nymph, and their influences on development and reproduction of F. occidentalis were studied. The results showed exposure of sublethal concentrations of spinetoram and azadirachtin to F. accidentalis had different degrees of effects on this insect pest. Under bisexual reproduction, the LC₂₅ spinetoram had no significant influences on pre-oviposition period, female adult longevity and fecundity, but male adult longevity was significantly shorter than the control. The LC₂₅ azadirachtin significantly reduced fecundity and prolonged pre-oviposition period. Under parthenogenesis, the LC₂₅ spinetoram and azadirachtin extended the pre-oviposition duration, whereas the LC₂₅ azadirachtin shortened the female adult longevity and significantly decreased fecundity. The LC₂₅ spinetoram and azadirachtin had different influences on developmental duration of each stage of next generation. The immature stage in treatment group of the LC₂₅ spinetoram was shorter than that in treatment group of the LC₂₅ azadirachtin, under bisexual reproduction or parthenogenesis. Intrinsic rate of increase (r_m) and finite rate of increase (λ) of population treated by the LC₂₅ spinetoram were higher than those of the control, whereas the r_m, R₀, and λ of population treated by the LC₂₅ azadirachtin were lower than those of the control. The findings indicated that the effects of the LC₂₅ spinetoram and azadirachtin on the development and reproduction of F. accidentalis were different. The LC₂₅ spinetoram had certain stimulating effect, whereas the LC₂₅ azadirach-tinon had significant inhibitory effect. Two biopesticides’ influences were related with the reproductive patterns of F. accidentalis.

Screening, identification and phosphate-solubilizing characteristics of phosphate-solubilizing bacteria strain D2 (Pantoea sp.)in rhizosphere of Pinus tabuliformis in iron tailings yard.

WANG Jun-juan, YAN Ai-hua, WANG Wei, LI Ji-quan, LI Yu-ling

2016, 27(11):  3705-3711.  doi:10.13287/j.1001-9332.201611.003

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Two strains of phosphate-solubilizing bacteria were isolated from the rhizosphere of Pinus tabuliformis in iron tailings vegetation restoration areas in Malan Town, Qianan City, Hebei Pro-vince. The bacterial strain D2 with strong phosphate-solubilizing capacity was obtained via screening with plate and shake flask. Based on the morphology, physiology and biochemistry, and the sequence analysis of 16S rDNA, the D2 was identified as a member of Pantoea sp. A fermentation experiment was conducted to investigate the effect of carbon and nitrogen sources on the phosphate-solubilizing capacity of the strain D2; under different nitrogen sources, the organic acids in liquid culture, as well as their types and contents were determined by high performance liquid chromatography. The results showed that the strain D2 was capable of efficiently solubilizing tricalcium phosphate, and the highest value of available phosphorus was up to 392.13 mg·L^-1 in liquid culture. The strain D2 displayed the strongest phosphate-solubilizing capability when glucose and ammonium sulfate were used as carbon and nitrogen sources in the culture media, respectively. Under varied nitrogen sources, the resulting organic acids and their types and contents were different. When the nitrogen source in culture media was ammonium sulfate, ammonium chloride, potassium nitrate, sodium nitrate or ammonium nitrate, all four organic acids, including oxalic acid, formic acid, acetic acid and citric acid, were produced. In addition, malic acid was uniquely produced when ammonium sulfate, ammonium chloride or ammonium nitrate was used as the nitrogen source. By Pearson’s correlation analysis, a significant positive correlation between the acetic acid content and the available phosphorus content was found (r=0.886, P<0.05), suggesting that acetic acid produced by strain D2 played an important role in promoting inorganic phosphorus dissolution, which was most likely to be one of the important phosphate-solubilizing mechanisms of the strain.

Predation of Poratrioza sinica Yang & Li by the adults of Coccinella septempunctata.

WU Peng-xiang, OUYANG Hao-yong, XU Jing, HE Jia, ZHANG Rong, ZHANG Run-zhi

2016, 27(11):  3712-3718.  doi:10.13287/j.1001-9332.201611.001

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To study predation by Coccinella septempunctata adults on 4 stages of Poratrioza sinica Yang & Li, predation functional response, mutual interference, density influence and preference of C. septempunctata on P. sinica were investigated in laboratory and preying effect in field. The study indicated that functional response of adult C. septempunctata to P. sinica could be fitted by Holling Ⅱ model, the daily maximum numbers of P. sinica eggs, 1^st-2^nd instar nymphs, 3^rd-5^th instar nymphs and adults preyed theoretically by the adult C. septempunctata were 112.6, 536, 415 and 113.9, respectively. In 30 days of adult’s life cycle, density of P. sinica inside cages could be decreased by 80.1% in the field. Searching efficiency of C. septempunctata to P. sinica 1^st-2^nd instar nymphs was 0.9451 and processing time was 0.001865, which were better than those of other stages. The maximum rate of P. sinica 1^st-2^nd instar nymphs preyed was 80.2% as the prey density was 100 heads per dish, so the ratio of predator: prey was 1:100. The density had a greater impact than mutual interference on C. septempunctata. When different stages of P. sinica co-existed equally, C. septempunctata preferred P. sinica adult in 100 heads per dish while P. sinica nymphs in 300 heads per dish. The study showed that C. septempunctata has the potential to be predator of P. sinica and the newly-hatched nymphs could be controlled more effectively by C. septempunctata adult in field.

Diurnal activity pattern and seasonal variations of captive Papio hamadryas.

CHEN Jing, WU Bing-lin, LU Qing-bin

2016, 27(11):  3719-3726.  doi:10.13287/j.1001-9332.201611.006

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Activity rhythms and time budgets are two important components of ecological influences on animal individual behaviors. We collected data on activity pattern using instantaneous scan sampling on captive hamadryas baboons (Papio hamadryas) in Hangzhou Wild Animal Zoo in Zhejiang, China from November 2012 to October 2013. The results showed that: 1) In the activity time allocation, the main activities (frequency percentage was more than or equal to 5%) included resting (42.5%), traveling (16.2%), playing (10.0%), feeding (9.8%), grooming (9.4%) and watching (7.3%), and the secondary activities (frequency percentage is lower than 5%) only accounted for a total of 4.8%. 2) Due to increasing in the feeding and watching time, and decreasing in the playing and grooming time in winter, their time budgets showed significant seasonal variation, but the resting and swimming time had no significant difference between the cold season and the warm season. 3) The diurnal activity rhythms of P. hamadryas showed two feeding peaks of morning and afternoon, and as the temperature gradually turned cold, feeding activity gradually increased with three feeding peaks, which might be a strategy of complementary energy against the cold season. 4) P. hamadryas only had a midday resting and grooming peak with multi peaks of traveling and playing in the warm season, and the swimming, playing and watching time rhythm had not obvious difference between the cold winter and the warm season, but there were multi peaks of resting in the cold winter. Therefore, their diurnal activity rhythm was not the same as other many primates (such as Nomascus nasutus, Propithecus verreauxi and Lagothrix sp.), the captive P. hamadryas in winter in Hangzhou area took a strategy of feeding for supplement energy to withstand cold rather than resting to reduce energy consumption. In short, Papio hamadryas reflects obvious rhythm with seasonal differences, which may be an adaptation to the influence of food and temperature changes in captivity.

Advances in research on mechanisms of seed pre-treatments.

LIU Xu, LIU Juan, LIU Qian, GAO Ya-ni, WANG Quan-zhen

2016, 27(11):  3727-3738.  doi:10.13287/j.1001-9332.201611.023

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Seeds play a vital role in nature and agro-ecosystems. The success of seed germination and the establishment of a normal seedling determine the propagation and survival of a plant species, but seed vigor is often seriously damaged because of seed aging, dormancy and the deterioration of natural habitat. Thus, exploring methods for improving germination quality is of great significance to ecology and the economy. Based on the latest international reports, seed pre-treatments are the most practical and effective methods for improving plant performance, increasing yields and enhancing stress resistance. This review provided a summary of the current pre-sowing treatment technologies and the physiological and biochemical responses of plants to these methods by addressing gene expression, cytological effects, enzyme system activities, material and energy metabolism, antioxidation mechanisms and signal transduction pathways. We also interpreted the mechanisms of the seed pre-treatment methods from aspects of seed germination acceleration and stress resistance enhancement. The bottleneck in seed pre-treatments at the cytological and molecular levels and the problems involved in their application were also discussed. Thus far, most studies had largely focused on the partial reaction alterations of plant biochemistry and enzyme activities, and they had generally been characterized by a lack of systematic and holistic study for applications to crop production. Finally, we proposed an outlook for further study in an attempt to provide a prospective and scientific reference for plant germplasm conservation, high-efficiency organic agriculture development and ecological environment re-construction.