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2017 Vol.15 No.3
Published 2017-06-30
1
GU Yalan, LIANG Yin, CAO Longxi, LU Huizhong, ZHANG Yugang
Characteristics of runoff and sediment yield of catchment area under 30 years vegetation restoration in red clay erosion badland
[Background]
The red soil region is one of the typical areas suffering serious soil erosion in southern China. The red clay badland is a kind of seriously eroded degradation and is still one of the main obstacle factors in enhancing regional soil quality and ecosystem function. Thus, suitable management is urgently needed, and systematic analysis and evaluation should be carried out. This paper is therefore conducted to evaluate the soil and water conservation benefit of the vegetation restoration measures in red clay badland.
[Methods]
Two field plots were built according to the natural drainage boundary 30 years ago. One is in the bare land as control and the other is vegetation restoration treatment. Runoff and sediment generation were monitored continuously under the natural rainfall condition. According to the long-term field plot monitoring data and rainfall event process information, the dynamic of runoff and sediment yield can be quantitatively described and the benefits of vegetation restoration can be evaluated.
[Results]
1) The runoff yield showed significant differences between the bare land and vegetation treatment at the 6th year of restoration. Sediment yield was approximately zero in the vegetation recovered plot after 8 years. The dynamic characteristics of both runoff and sediment yield throughout a year followed the same trend as rainfall, concentrating from April to June. The efficiencies for vegetation restoration in reducing runoff and soil loss were more than 40% and 90% respectively. The vegetation significantly reduced the coefficients of regression curves, meaning that the runoff and sediment yield in the restored land tended to be less than that of the bare land with the same precipitation. 2) The dynamic of the runoff and sediment yield during a rainfall event process showed multi peak curves and consistent with the trend of the rainfall intensity (I
60max
). The time to runoff and sediment yield in the vegetation treatment generally 1 hour delayed compared with the bare land. Meanwhile, the peak runoff and sediment in the restored land were also delayed and decreased by 67%-83%. The benefit of vegetation on reducing peak value of the runoff under moderate rain was better than that under rainstorm or heavy rain. 3) Comparing with the bare land, the loss of total nitrogen (TN), total phosphorus (TP) and total potassium (TK) in the restored land were reduced by 54.62%, 57.53%, and 56.46% respectively. During a rainfall and runoff process, the total losses of TP were obviously lower than the TN and TK. The concentration of TN and TK in rainfall process fluctuated and was higher than TP which was relatively stable.
[Conclusions]
The rapid restoration of vegetation can effectively control the surface runoff and sediment yield, delay runoff generation process and reduce peak flow. Meanwhile, recovery measures can significantly reduce nutrient loss in runoff and sediment. Therefore the vegetation restoration can be applied in local ecology recover and soil management. This study can provide a scientific basis for the assessment of the water and soil conservation benefit of vegetation restoration in red clay badland.
2017 Vol. 15 (3): 1-8 [
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9
FANG Xiaochen, WANG Chunhong, ZHANG Ronghua, ZHANG Guangcan, XING Xianshuang, YANG Rui, ZHAO Jie
Soil particle size distribution characteristics under different land use types in Yinghe Watershed of Funiu Mountain Area
[Background]
The soil erosion of Funiu Mountain Area has been one of the most serious problems in Huaihe River Basin even rocky mountain areas of northern China. Sloping farmland is the main source of soil erosion which causes loss of fine particle, degradation of the soil structure and performance. The soil fractal theory has been an important method to quantify particle size distribution (PSD). In this paper, we explore the degradation degree of sloping farmland soil physical property with fractal theory in Funiu Mountain Area in Yinghe Watershed, Lushan County of Henan Province.
[Methods]
On the basis of small watershed investigation, we selected four land use types (five vegetation types) as research subjects and set sample plots. In every land use type plot, three temporary sample plots (20 m×20 m) were set to dig surface soil (0-20 cm) with 5-point sampling method. The soil from the same plot was well mixed to dry for the determination of particle size distribution. After the determination by the laser granulometer, the frequency distribution of volume of the soil particle (< 2 mm) under different land use types was obtained. Then we divided the volume of soil particle into 7 levels according to American standard:clay:<0.002 mm, silt:0.002-0.05 mm, very fine sand:0.05-0.1 mm, fine sand:0.1-0.25 mm, middle sand:0.25-0.5 mm, coarse sand:0.5-1.0 mm, very coarse sand:1-2 mm. By soil particle volume fractal model and general dimension spectrum, the fractal dimension
D
v
and multi-fractal parameter
D
q
were obtained. Among them, when
q
=0, 1, 2, the
D
q
is respectively
D
0
,
D
1
,
D
2
. After the above method and comprehensive analysis, we studied the composition of soil particles size, variation of fractal dimension characteristic parameter and effect on PSD uniformity under four land use types.
[Results]
1) The
D
v
was manifested as:the maximum was arbor forest (2.658), and the sloping farmland was the smallest one by 2.489. The multi-fractal parameters (
D
0
,
D
1
,
D
2
) was manifested as:the maximum was arbor forest (0.941, 0.926, 0.91), and the sloping farmland was the smallest one by 0.927, 0.899, 0.849. All the fractal parameters were manifested as:sloping farmland < shrub-grass slope land and terraced land < arbor forest. 2) There were significant positive correlation between
D
v
,
D
0
,
D
1
,
D
2
and clay, silt volume fraction, and all of them had significantly negative correlations with sand volume fraction.
[Conclusions]
Soil fractal theory and multi-fractal theory can be used to quantitatively characterize differences of soil texture granularity distribution and heterogeneity; the coarse graining and heterogeneity of sloping farmland is higher than other land use types, the loss of soil fine particle (clay and silt) lead to the increase of degree of coarse graining and heterogeneity of sloping farmland.
2017 Vol. 15 (3): 9-16 [
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17
WANG Dan, HA Yuling, LI Zhanbin, YU Kunxia, BO Chongde, ZHANG Huwei, SU Liping
Evaluation on the operation risk of dam system in the typical watersheds of Ningxia
[Background]
Dilapidated dam will seriously threaten people's life and property safety, therefore, the identification and research of check dam's operation risk is particularly important.
[Methods]
Selecting Chelugou dam system of Ningxia as the research object, a set of relatively complete evaluation index system of operation risk of both single dam and the whole dam system were extracted and established respectively from four aspects of engineering, management, economy and structure. With the method of improved AHP (Analytic Hierarchy Process) to calculate the index weight, the operation risk of single dam under seven different storm return periods and that of the whole system under the return period of 300 years were calculated and evaluated comprehensively, meanwhile the risk map of temporal and spatial distributionof single dam was made as well.
[Results]
For the operation risk of single dam, it showed that there were three check dam including Chelugou, Qianzu and Dongzhuangwan, which operation risk grade grew from class Ⅲ(generally dangerous stae) under the occuring period of 10 years to classⅡ(dangerous state) under the occuring period of 50 years, 100 years, 300 years, which need to be taken seriously. On the whole, the project and economic risk of single dam in Chelugou dam system were generally high, which exceeded 0.8 and 0.4 perspectively, that was related to, the majority of dam in Ningxia was given priority to water storage. For the evaluation of dam system, when suffered a heavy rain of period 300 years, the operation risk of Chelugou basin from high to low were as follows:Wangzhao unit(0.51, classⅢ) > Qianzu unit(0.50, classⅢ) > the whole basin(0.44, classⅢ) > Dapin unit(0.39, classⅣ) > Panluwan unit(0.35, classⅣ), meaning that all dam unit were in the generally dangerous state or generally safe state. And from the view of whether dam system unit or the whole basin, the basin were all in a safe state of operation. It could also been seen from the results that the key dam unit was the Wangzhao unit and Qianzu unit which influenced the operation safety of the whole dam system. In addition to building spillway, it was necessary to deal with the damaged parts of dam body as well as water release works as soon as possible to eliminate hidden dangers.
[Conclusions]
The paper realized the evaluation work of operation risk of single dam, check dam unit as well as the dam system on the whole. These results would provide certain reference to the safety forecast warning of check dam in the region and help the administrative department of rapid decision-making, so as to ensure the safe and stable operation of check dam and lay the foundation for establishing the safety emergency response mechanism and operation measures.
2017 Vol. 15 (3): 17-25 [
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565
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26
ZHANG Hong, LI Ying, ZHANG Yujun, ZHU Jinfeng, LIU Shiliang, LIU Fang, JIANG Guiying
Effects of biochar on nitrogen transformation and the microbial biomass nitrogen under different nitrogen application rates
[Background]
This paper studies the effect of applied biochar on the nitrogen (N) transformation under different N levels in the tobacco-planting soil, because the C/N ratio in the soil for continuous planting tobacco in Henan province is not balanced, resulting in the tobacco quality reduced.
[Methods]
The field experiment was carried out with different N levels under the biochar application; it is located in Daguo town of Linying County, Henan province (E113°81', N33°79'). Five treatments were set as:1) no N no biochar (CK); the other four applied with 1 600 kg/hm
2
biochar, with four N levels:2) 0 kg/hm
2
(N0); 3) 37.5 kg/hm
2
(N1); 4) 52.5 kg/hm
2
(N2); 5) 67.5 kg/hm
2
(N3). Based on the five sample points, the total N (TN), available N (AN), nitrate N (NO
3
-
-N) and ammonium N (NH
4
+
-N) in three soil layers (i.e. 0-20 cm, 20-40 cm, and 40-60 cm) as well as the soil microorganism biomass N (SMBN) in 0-20 cm soil layer were measured and analyzed.
[Results]
The biochar application reduced the N content in the deep layer, which indicated that it elevated N sequestration in top soil layer. Compared with the CK, the decrement of TN, AN, NO
3
-
-N, and NH
4
+
-N content was 11.21%, 49.07%, 42.29% and 31.35%, respectively under the no treatment. The AN, NO
3
-
-N, and NH
4
+
-N content mainly existed in 0-20 cm soil layer, and all of them increased with N application rate. The highest content of TN, AN, NH
4
+
-N occurred under N3 treatment, which was 2.10 g/kg, 261.86 g/kg, 264.90 mg/kg, and 49.80 mg/kg, respectively. While the NO
3
-
-N content reduced with the soil layer increased, and it concentrated in 0-20 cm layer with the highest level as 264.90 mg/kg in N3 treatment. Moreover, the NO
3
-
-N content in 20-40 cm soil layer was significantly different from that of other soil layer under different N level. The effect of N application rate on its transformation presented before 30 d after the tobacco transplanted. The biochar application increased the SMBN after tobacco transplanted 60 d, while the effect of the amount of N fertilizer on the microbial biomass nitrogen entropy was mainly reflected after tobacco transplanted 30 d.
[Conclusions]
The effect of N application rate on soil N content mainly in 0-20 cm soil layer, and it was significantly affected during the early stage of tobacco growth. The biochar restrained the N transformation in soil with lower N application rate, but with little effect under higher N application rate. It is suggested that the biochar combined with 67.5 kg/km
2
N application is the optimal practice to improve soil N content in central area of Henan province.
2017 Vol. 15 (3): 26-35 [
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36
MA Qianhong, ZHANG Guanghui, GENG Ren, WANG Hao
Present condition analysis of sloping farmland soil quality in the eastern water erosion zone of China
[Background]
Soil quality is the foundation of land productivity. Sloping farmland is an important kind of cultivable land resource in the water erosion zone of China. The current study is aimed at investigating the general situation of sloping farmland soil quality in this region.
[Methods]
We collected 36 soil samples from the soil layer of 0-20 cm in this region dispersedly and tested 28 soil physical and chemical indicators for each soil sample. The method of principal component analysis (PCA) was used to select the key indicators for soil quality analysis. Membership functions were used to transform the key indicators into dimensionless data, and the weighted multiplication method was applied to calculate soil quality index (SQI) for each sampling point.
[Results]
1) The variation coefficient of available P was the maximum, and the variation coefficient of microaggregate volume fraction was the minimum. Most of the indicators had intermediate variability. The mean variation coefficient of soil physical indicators was much smaller than soil chemical indicators. 2) The key indicators for assessing soil quality were clay volume fraction, silt volume fraction, microaggregate volume fraction, soil organic matter, pH,Cd and Cr. Cr had the highest membership value, while pH had the lowest membership value. The membership values of Cd were significantly different between the six secondary partition regions. 3) The mean value of the SQI was 0.64±0.16. There was no significant difference about SQI between the six secondary partition regions. The proportions of SQI ranked as low, middle, high, higher level were 8.33%, 38.89%, 36.11% and 16.67% of the total area of sloping farmland, respectively.
[Conclusions]
On the whole, the general situation of sloping farmland soil quality in the region was fine, but we still need to strengthen fertilization and amelioration in the regions with low soil quality. These findings of the study had great significance for understanding and maintaining sloping farmland soil quality, soil quality grade classification and regionalization, exploiting and utilizing land resource reasonably in the eastern water erosion zone of our country.
2017 Vol. 15 (3): 36-42 [
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43
LEI Xueming, WU Jianping, FENG Yan, TONG Hao, TU Longping, LIU Wenfei, FAN Houbao
Impacts of slash burning on soil nutrients of the clear-cutting site of
Cunninghamia lanceolata
plantation in Sanming, Fujian Province
[Background]
Fire is a controlling factor in terrestrial ecosystems. Moderate frequency and intensity of fire can be beneficial for the structure and functioning of ecosystems, thereby maintaining forest biodiversity and nutrient cycling, and improving soil fertility in forest ecosystems.
[Methods]
Field investigations and lab analyses were conducted to study the effects of slash burning on soil nutrients on the clear-cutting sites of
Cunninghamia lanceolata
plantation. Three slope locations (i.e. upper slope, middle slope and lower slope locations) were selected to monitor the dynamic changes in soil available nutrient status, including nitrate nitrogen (NO
3
-
-N), ammonium nitrogen (NH
4
+
-N) and available phosphorus (A-P). The soil samples were collected one time before the burning and three times after the burning (i.e. 2 months, 1 year, and 2 years). The changes of soil available nutrient on different recovery times and slope locations were examined.
[Results]
1) The concentration of NO
3
-
-N increased in the second month and the first year after the burning but declined slightly in the second year, in comparison with that prior to the burning. Additionally, the concentration of NO
3
-
-N in upper slope location was lower than those in other slope locations within a year of burning. The averaged concentration of soil NO
3
-
-N from different fire time exhibited the following trend:the first year of burning (27.53mg/kg) > the second month of burning (26.03 mg/kg) > before the burning (22.32 mg/kg) > the second year of burning (15.33 mg/kg). 2) By contrast, the concentration of NH
4
+
-N showed an opposite trend:declining within the first year from 11.52 mg/kg (before the burning) to 8.48 mg/kg (the second month of burning) and 5.19 mg/kg (the first year of burning). However, it increased significantly after the second year of burning, reaching 8.99 mg/kg. 3) There was no significant difference in A-P concentration among different slope locations across time. A-P remained similar through the first year of burning, ranging between 3.05 and 4.64 mg/kg. Nevertheless, it increased in the second year of burning (11.71 mg/kg), indicating that burning accelerated soil nutrient mineralization. 4) The ratio of IN/A-P (inorganic nitrogen/available phosphorus) did not change significantly in the first year of burning, while it reduced significantly after the second year of burning (between 1.98 and 2.63), largely due to rapid increase in available phosphorus concentration.
[Conclusions]
On the whole, the short term effect of fire speeded up the soil available nutrient cycling, and the soil nutrient status was improved. However, we should pay attention to the phenomenon that large amounts of nutrient losses from the site may occur in the meantime. The main goal of this study was to enrich the database of long-term slash burning on soil nutrients, and provide scientific theoretical basis for plantation management in the burned forest area.
2017 Vol. 15 (3): 43-50 [
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51
LI Xiaoyuan, ZHANG Wentai, LI Jiangui, ZHONG Yating, SU Yue, ZHAO Jingwen
Effects of five soil management measures on runoff and sediment reduction in Ili Valley of Xinjiang
[Background]
The grade of water erosion is moderately strong in Ili Valley of Xinjiang. This work aims to explore the effects of different soil management measures on runoff and sediment reduction, and to provide sustainable utilization of land resources and effective measurement of soil and water conservation.
[Methods]
Artificial rainfall simulation experiments with 3 rainfall intensities (20 mm/h, 10 mm/h and 36 mm/h), 5 soil management measures (bare land,
Ceratocarpus arenarius
L. covered,
Kochia prostrate
(L.) Schrad. covered, fish scale pit, and horizontal ditch), and totally 15 times of experiments were conducted to analyze runoff and sediment process in the field. Meanwhile, with Excel 2007 and SPSS 19.0, we analyzed the relationship between sediment concentration and runoff rate, and compared the effects of runoff and sediment reduction under different rainfall intensities.
[Results]
The initial runoff time of bare land was so short that suffered rainfall erosion easily, while runoff of horizontal ditch was never happened under 3 artificial rainfall simulations. Although
C. arenarius
L. covered measure did not produce runoff under 20 mm/h rainfall intensity, there was runoff when the rainfall intensity was 10 mm/h. The reason for this phenomenon was due to higher antecedent soil moisture for the second rain, i.e., 10 mm/h rainfall. The runoff rate and sediment concentration increased as rainfall intensity increased for all experiments. By using linear regression analysis in SPSS 19.0, we found that the relationship between the sediment concentrations and the runoff rates under the measures of bare land,
C. arenarius
L. covered,
K. prostrate
(L.) Schrad. covered and fish scale pit were all linearly significant. And we did not obtain the data of horizontal ditch because it was never happened runoff under 3 rainfall intensities. However, the sediment concentration decreased with the increase of the runoff rate under
K. prostrate
(L.) Schrad. covered measure. Sediment and runoff reduction of all measures listed in the following order:horizontal ditch >
K. prostrate
(L.) Schrad. covered > fish scale pit >
C. arenarius
L. covered > bare land. Therefore, the measures of fish scale pit and
K. prostrate
(L.) Schrad. covered showed more obvious effects on runoff and sediment reduction than the other soil management measures.
[Conclusions]
This study demonstrated that the measures of horizontal ditch and
K. prostrate
(L.) Schrad. covered effectively reduced runoff rate and sediment concentration in Ili Valley of Xinjiang and should be applied in soil and water conservation in this area.
2017 Vol. 15 (3): 51-57 [
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661
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58
Li Zhiguang, Cao Wenhua, Niu Yong
Test and calibration of a real-time hillslope runoff measuring device
[Background]
Water and soil loss has been a major environmental issue, and people's demands on environment quality are raised constantly in China. In this context, a nationwide water and soil loss monitoring network was set up, the count of water and soil loss monitoring stations increased to 738 recently. Although network built quickly, but the dedicated devices used in water and soil loss monitoring still fall behind very much. For example, manual throughfall collecting tank was invented centuries ago, but it's still used widely now in China. Therefore, developing and testing automated dedicated devices used in water and soil loss monitoring is an urgent and long-term task, which can enhance people's ability of monitoring and controlling water and soil loss. Automatic hillslope runoff measuring device is a gauge that can be used in a scale of runoff plot to replace human beings to measure, which can enhance the monitoring efficiency greatly.
[Methods]
This paper took the measurement accuracy of a Runoff & Sediment Real-time Measuring Device as research object, the relative errors between theoretical value and measurement value were calculated based on the artificial runoff-producing simulation. Analysis of partial correlation was used to uncover the cause of error. With regression analysis, a fitted relationship between the runoff true value and the measured value was established.
[Results]
The results showed that the range of the relative error of runoff was -4.33%-24.01%,and the range of the stabilization time was 55-130 s. Based on the analysis of partial correlation, the stabilization time for measured values had a significantly positive correlation with sediment concentration, and had a significant inverse correlation with design flow (
P
<0.05). The accuracy of measurement had a significantly positive correlation with sediment concentration and design flow, but both sediment concentration and design flow presented limited influences on accuracy of measurement(
α
=0.05). Regress equation between the measurement of runoff and revised values was found by using the regression analysis. It was proved that accuracy of the measurement and the stabilization time for runoff measurements was significantly improved. Furthermore, the research also demonstrates that increasing waves cutting device and enlarging the size of waves filter can be conducive to improve accuracy of the measurement.
[Conclusions]
These results were beneficial to understand the measuring performance of device in this study. With the rainfall intensity range 3.60 mm/h -66.96 mm/h, runoff can be measured accurately by the device, the range of rainfall intensity mentioned above can represent different rain types, such as moderate rain, heavy rain and rainstorm in northern China. For improving measurement accuracy in the future,the impact of silt content and mechanical composition should be considered and explored.
2017 Vol. 15 (3): 58-64 [
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65
YANG Dan, SUN Yongtao, ZHUANG Jiayao, ZHANG Jinchi, GE Bo, FAN Guohua
Variation characteristics of shallow-soil temperature under typical stands in the Yangtze River Delta
[Background]
The soil temperature directly determines the quality of soil resources, and affects plant's growth, development, reproduction and distribution. As the largest economic developed area in China, the hot summer in the Yangtze River Delta demands high requirements for the rational allocation of artificial vegetation communities. This work aims to understand the changes of temperature of shallow-soil under typical stands in the Yangtze River Delta, and to reveal the effects of forest on regulating temperature of shallow-soil.
[Methods]
The soil temperature sensor EM50 was used to conduct long-term monitoring, from June 2012 to May 2013, on temperature of shallow-soil (5 cm, 10 cm, and 15 cm) of
Quercus acutissima
stand,
Phyllostachys edulis
stand and
Cunninghamia lanceolata
stand in Tongshan of Nanjing. With nudaton as the control, the temperature variation characteristics of shallow-soil under three stands were analyzed by Microsoft Excel 2007, Origin 8.5, SPSS 19.0 and LSD.
[Results]
The diurnal variation and annual variation of soil temperature under forest was smaller than that in nudation. The diurnal range of soil temperature was in descending order of nudation,
C. lanceolata
stand,
P. edulis
stand and
Q. acutissima
stand and the annual variation range was in descending order of nudation,
C. lanceolata
stand,
Q. acutissima
stand and
P. edulis
stand. The forest presented the effect of decreasing the soil temperature in summer and autumn, moreover,
P. edulis
stand(about 1-3℃)showed the best effect of reducing soil temperature. The forest had the function of increasing soil temperature in winter and spring, moreover,
C. lanceolata
stand(about 0.1-1℃)showed the strongest effect of increasing soil temperature. The forest caused the decrease of the annual average temperature, and
P. edulis
stand decreased the annual average temperature about 1-2℃,
C. lanceolata
stand and
Q. acutissima
stand about 0.5-1.5℃, respectively. The forest lagged the time of the daily maximum and minimum temperature of soil, and the lagging effect was descending in order of
C. lanceolata
stand,
P. edulis
stand and
Q. acutissima
stand. The highest temperature of soil temperature was lowered by forest and the lowest temperature of soil temperature rose in spring and winter. The effect of reducing daily highest temperature of soil temperature was the most significant under
Q. acutissima
stand. In the spring and winter,
Q. acutissima
stand and
C. lanceolata
acted as the best role in increasing daily lowest soil temperature.
[Conclusions]
The diurnal range and annual range of soil temperature under both
Q. acutissima
stand and
P. edulis
stand was smaller than that under
C. lanceolata
stand. For the ability of reducing soil temperature in summer and autumn and raising the temperature in winter and spring, the
P. edulis
stand was better than
Q. acutissima
stand and
C. lanceolata
stand. For the ability of lagging the time of the maximum and minimum temperature of soil, the
C. lanceolata
stand was better than
P. edulis
stand and
Q. acutissima
stand. For the ability of reducing the maximum temperature of soil and raising the lowest temperature of soil,
Q. acutissima
stand was better than
P. edulis
stand and
C. lanceolata
stand. This conclusion can provide reference for soil environment protection and tree species selection.
2017 Vol. 15 (3): 65-73 [
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444
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468
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74
ZHANG Zhihua, LI Xiaoyan, JIANG Zhiyun, SANG Yuqiang
Changes in soil properties and plant community characteristics among different vegetation restoration models in the semiarid steppe zone of Inner Mongolia in China
[Background]
"Grain for Green Program" (GGP), i.e., reconversion of cropland into forest or grassland, initiated by Chinese government has a profound impact on mitigating environmental degradation. After cropland is re-converted into grassland, land use and vegetation can be altered radically within a short period, and soil physical, chemical, and microbial properties can be improved. In general, natural recovery and artificial forestation/grass planting are two main ways to restoration after re-conversion from cropland to grassland. However, there has not yet formed a unified conclusion on which way is more favorable to improve the vegetation community and soil environment. The objectives of this study were hence to discover the differences in characteristics of vegetation community and soil properties between natural recovery (N-CG) and artificial grass planting (P-CG) in the semiarid steppe region of north China, and then to assess a more suitable restoration ways in the study area.
[Methods]
Three sites were selected, representing two restoration ways (natural recovery and artificial forestation) and natural grassland (NG), respectively. Vegetation cover, biomass and species diversity were investigated by quadrat method in the field. Soil samplings were collected with different depths to investigate soil properties including organic matter (SOM), total nitrogen (TN) and phosphorus (TP), bulk density (BD) and particle size distribution. Particle size composition was determined by the hydrometer method and SOM was measured by the K
2
Cr
2
O
7
-H
2
SO
4
oxidation method. Additionally, TN was measured using a Nitrogen/Carbon Analyzer and TP was measured by molybdenum blue colorimetry, after H
2
SO
4
-HClO
4
digestion.
[Results]
1) Species diversity, plant coverage, aboveground and belowground biomass were significantly (
P
<0.01) lower in P-CG among the three typed sites, and the differences between N-CG and NG were not significant. Meanwhile, species composition in N-CG was similar with NG, compared with P-CG. 2) Surface soil (0-10 cm) properties were deeply affected by different restoration ways. P-CG tended to have higher bulk density and sand content, but lower SOM, TN, silt and clay content than N-CG at the soil depths of 0-10 cm, although the differences were not significant. Moreover, NG had the lowest bulk density and sand content, and the highest SOM, TN, TP, silt and clay content.
[Conclusions]
Soil properties and plant community characters did not return to natural grassland status as before cultivation after 12 years of re-conversion in our study area. N-CG might be a more suitable restoration way to facilitate vegetation community and improve soil physicochemical properties in the study area compared with P-CG. Extra efforts are needed to persistently investigate the changes of vegetation and soil properties in a long time within different restoration ways and to make reliable policy decisions while choosing suitable ways for re-conversion from cropland to grassland in the semiarid steppe region of north China.
2017 Vol. 15 (3): 74-80 [
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575
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495
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81
GAO Zhiqiang, SHI Mingchang, YANG Wentao, SUN Na, WANG Xiaojing
Rapid extraction of land parcels from soil and water conservation supervision-oriented productive and constructive projects in the Loess Plateau
[Background]
The productive and constructive project (PCP) is one of the main sources of man-made soil and water loss in the Loess Plateau. Acquiring the location and attributes of PCP land parcels is critical to soil and water conservation supervision, management, and protection. Traditional ways of mapping PCP land parcels mainly rely on manual interpretation of remote sensing images, which is time-consuming, subjective and expensive.
[Methods]
Based on GF-1 images, this paper presents a rapid object-oriented method to extract PCP land parcels in the Loess Plateau. Firstly, we analyzed the separability of 29 typical PCP land parcel components in the study area. Six kinds of components were selected as extraction markers. Then, on this basis, an object-oriented multi-level extraction model, which united the multi-resolution segmentation algorithm and the fuzzy classification algorithm, was developed to extract these six kinds of components mentioned above. Final extraction results were achieved after automatic extraction and post-processing procedures.
[Results]
Results showed that six kinds of marked objects, which were buildings and structures, hardened grounds, bare lands, waste slags, coal covered areas and water areas, were reliable to sign PCP land parcels in the Loess Plateau. With the object-oriented multi-level extraction model, the extraction results were considered sustainable and efficient. The quantitative and area accuracy of extracting block-type PCP land parcels was 95.03% and 85.19% respectively, while the length accuracy of extracting line-type PCP land parcels was 86.34%. Besides, with the same hardware and software configuration, the overall time was 80% less than the traditional method. The results validated that the multi-resolution segmentation algorithm portrayed the edges of different objects correctly in several scales, and that the fuzzy classification algorithm described the features of the objects in a more plentiful and accurate way. It was proved that the object-oriented extraction method was suitable for extracting PCP land parcels based on GF-1 imagery. A few of block-type PCP land parcels were failed to be extracted for the broken composition and inadequate extracting area. The interferences of surroundings decreased the extraction accuracy of line-type PCP land parcels.
[Conclusions]
Compared to manual interpretation, this proposed method shows a solid advantage on extraction efficiency with a high accuracy, which can be applied for rapid extraction of PCP land parcels in a large region in the Loess Plateau. This method provides a better technical support for efficient and accurate implementation of soil and water conservation supervision and management.
2017 Vol. 15 (3): 81-89 [
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668
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90
AI Shaoshui, LI Yangyang, CHEN Liru
Responses of the shoot growth in
Salix psammophila
and
Caragana korshinskii
to manipulated precipitation variation
[Background]
Water is the major factor limiting plant growth on the water-wind erosion crisscross region of the Loess Plateau, which is being exacerbated by the precipitation reduction related to global climate change and the decline of groundwater level due to large-scale energy development such as coal mining and oil exploitation. How local vegetation respond to this decreased water availability is important for the understanding of their adaptation and survival in the future.
[Methods]
Using precipitation manipulation experiment (the contrast, +45% of precipitation by irrigation and -50% of precipitation (Dry) by partial exclusion), the growths of different classes of branching shoots to varied simulated precipitations in
Salix psammophila
and
Caragana korshinskii
were studied during the second year of precipitation manipulation.
[Results]
1) For
S. psammophila
, the basal diameter, length and aboveground biomass of branching shoots within 10-15 mm class showed some responses to varied precipitation, the length and aboveground biomass of shoots with 15-20 mm class also presented certain responses, drought decreased the length and aboveground biomass of 10-15 mm class, and irrigation increased the length and aboveground biomass of 15-20 mm class. No responses for other classes of shoots were found. 2) For
Caragana korshinskii
, the radial growth of shoots with basal diameter < 20 mm presented significant responses to precipitation variation, but the responses of height growth of shoots were only found for shoots with basal diameter < 10 mm, suggesting a more sensitive response in smaller classes of shoots. Irrigation significantly increased aboveground biomass in shoots with basal diameter < 10 mm whereas drought did not decrease aboveground biomass of this class. For shoots with basal diameter of 10-20 mm, irrigation did not increase the biomass but drought significantly decreased the biomass. 3) Irrigation increased aboveground biomass per plant by 11.3% in
S. psammophila
and 35.5% in
C. korshinskii
, drought decreased aboveground biomass per plant by 14.2% in
S. psammophila
and 36.8% in
C. korshinskii
.
[Conclusions]
The results suggest that precipitation variation caused a greater effect on the growth of
C. korshinskii
than that of
S. psammophila
, and the growth of
C. korshinskii
showed a greater flexibility to varied precipitation, the reasons may be related with the differences of root water extraction source, soil infiltration properties and internal plant water redistribution, etc. These results may not only provide the insight of the adaptative mechanism how two shrubs cope with drought but also be conducive to forecast the growth dynamics and productivity of these two shrubs under future projected precipitation variation.
2017 Vol. 15 (3): 90-98 [
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426
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99
LI Qiang, LIU Guobin, ZHANG Zheng, MA Chunyan, BAI Yun, ZHANG Chenchen
Quantitative studies on root reinforcement resisting flow-induced erosion in the sandy loess region
[Background]
In semi-arid areas, soil erosion is a serious threat to land productivity and sustainability for natural and human-managed ecosystems. Traditional vegetation techniques are recognized as effectively in reducing soil erosion, whereas the most evident vegetation source that protects soil against erosion is root wedging, which is an important mechanism where roots can bind soil together and tie weak surface soil layers into strong and stable subsurface layers. Plant roots significantly affect soil erosion process of overland flow by physical consolidation (root link and root-soil adhesive) and biological chemistry functions. The purpose of this study was to evaluate the relative contributions of root link, root-soil adhesive as well as root biological chemistry functions to soil reinforcement. Such study could provide the theoretical explanation for root reinforcement resisting erosion in the flow-induced erosion regions.
[Methods]
For this purpose, a simulated scouring experiment was conducted on a sandy soil with sand content 36.8%, silt content 51.2% and clay content 12.0%. Three treatments considered were:1) fallow (CK), 2) root-penetrated soil and 3) simulated-root-penetrated soil. Each treatment had four replicates. Rectangular, undisturbed soil samples (20 cm×10 cm×10 cm) were taken in the fallow and root pans and were conducted with a hydrological flume (2 m×0.10 m). The flume contained an opening at its lower base, equaling the size of metal sampling box, so that the soil surface of soil sample was at the same level of the flume surface. Space between the sample box and the flume edges was sealed with painter's mastic to prevent edge effects. The slope of the flume bottom could be varied and clear tap water flow was applied at 4.0 L/min rate discharge on a washing flume slope of 15° for 15 min. During the 15 minutes of each experiment, samples of runoff and detached soil were collected every 1 min in the first 3 min and 2 min in the following time using 10 L buckets for determining sedimentation. Therefore, this paper analyzed the relative role in creating the soil configuration of soil resistance to erosion quantitatively, using no root-penetrated soil, root-penetrated soil erosion simulation test.
[Results]
The results showed that the physical consolidation effect was the key role in soil erosion resistance, accounting for 70.9% in the total root effect. Compared with alfalfa density of 90 plants/m
2
, physical consolidation effect in the treatment of 360 plants/m
2
increased by 6.8%. In addition, the root string function was the key manner in a proportion of 78.2% in the physical consolidation effect. Exponential function well expressed the relationship between root physical consolidation effect and root surface area density (
P
<0.01).
[Conclusions]
Physical consolidation effect is the key role in soil erosion resistance, and root surface area density can reflect the root soil consolidation effect.
2017 Vol. 15 (3): 99-104 [
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644
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440
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105
ZHAO Hengkang, CAO Binting, JIAO Juying
Characteristics of soil erosion of different plant communities converted from slope cropland in the hilly-gully region of the Loess Plateau
[Background]
The severe condition of soil and water loss in the Loess Plateau has resulted in critical agricultural and environmental problems. Vegetation restoration plays an essential role in controlling the soil erosion in the Loess Plateau. Yet there were few researches on analyzing the characteristics of soil erosion of different plant communities converted from slope cropland in the region.
[Methods]
The research was conducted between 2012 and 2015. Based on the succession of local plants, 10 plant communities on abandoned slope croplands in 4 watersheds of Ansai County were selected and were classified in 4 groups:naturally restored herbage community (
Artemisia scoparia, Stipa bungeana, Bothriochloa ischaemun, Artemisia gmelinii
, and
Artemisia giraldii
), naturally restored shrub community (
Sophora viciifolia
), artificially established shrub community (
Caragana intermedia
and
Hippophae rhamnoides
) and artificially established arbor community (
Robinia psendoacacia
and
Populus simonii
). Totally 45 plots were selected and in each of these communities 3-6 plots were selected, in each plot 3 quadrats were placed as repetition. Annual soil erosion intensity was monitored by erosion pins placed in these plots. Characteristics of soil erosion of different plant communities were analyzed with ANOVA, combined with the hydrologic years divided by the characteristics of rainfall. Gray theory was used to determine the influence of potential indices caused soil erosion.
[Results]
Rainfall in research area was distributed unevenly, and rainfall erosivity was the driver factor causing the differences of soil erosion intensity of plant communities in different years. The ability of controlling soil erosion depended on the species of plant community:naturally restored shrub community (1 285.36 t/km
2
) > naturally restored herbage community (2 152.65 t/km
2
) > artificially established shrub community(2 320.50 t/km
2
) > artificially established arbor community(2 661.14 t/km
2
). The soil erosion intensity of
Robinia psendoacacia
was the largest (3 875.02 t/km
2
) among these plant communities. Gray correlation analysis revealed that the rainfall and slope gradient had more impact on soil erosion than coverage in all communities. In shrub and arbor communities, the effect of slope gradient > rainfall, but in herbage communities, rainfall > slope gradient. When mentioned coverage, in natural restored community, cover of litters > vegetation cover; and in artificially established community, vegetation cover > cover of litters.
[Conclusions]
Under current status of vegetation, effects of precipitation on soil erosion reduced effectively in undisturbed plant communities. Natural vegetation should be restored initially with trees and shrubs introduced by human at proper time and place. Meanwhile, the undergrowth vegetation and litters in forest communities should be promoted earlier and protected, meanwhile human disturbances should be reduced as more as possible.
2017 Vol. 15 (3): 105-113 [
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617
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583
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114
SUN Yongkang, LIU Hanxiao, ZHANG Yan, MA Deli, ZHAO Tingning
Amelioration effects of dress-soil on limestone spoil at different particle sizes
[Background]
The protection and restoration of the ecological environment has attracted the world's attentions and became the focus of the research field. The researchers have been focusing on the improvement of the physical and chemical properties of mine spoil by using organic fertilizer, water retaining agent, garden waste, sludge, and other materials. However, the influences of different particle size and amount of spoil on soil moisture and plant growth have been ignored, thus we conducted this research to understand the amelioration effects of dress-soil at varied ratio on limestone spoil at different particle sizes.
[Methods]
We chose limestone quarry spoil from Fangshan District of Beijing as research materials, and then sieved it into 20-40 mm, 10-20 mm, 2-10 mm and < 2 mm. For simulating the particle size distribution of actual spoil, we used the spoil of above 4 particle sizes to create 12 kinds of spoil by combining them in varied ratios, and then mixed the dress-soil in the proportion of 0%, 20%, 40%, 60%, 80% and 100%. We selected the pot experiment, and sowed the
Festuca elata
100 seeds in mixed spoil per pot, and measured the survival rate, height, biomass and root-shoot ratio in the following two years. For comparing the bulk density, porosity, capillary water holding capacity and maximum water holding capacity of the mixed spoil before and after the pot experiment, we took and tested the samples by ring knife method. The experiment data was processed by Excel2016 and SPSS19.0 software for Pearson correlation analysis.
[Results]
The influence of dress-soil improvement of limestone spoil reflected certain irrigation sedimentation process, and adding and mixing dress-soil effectively improved spoil water holding capacity and subsequently improved the growth of tall fescue. The spoil water properties correlation order of different particle size by the amount of dress-soil addition was 20-40 mm < 10-20 mm < 2 mm < 2-10 mm, and the correlation order of tall fescue growth was 2 mm < 2-10 mm < 10-20 mm < 20-40 mm. The optimal dress-soil ratio for the spoil of < 2 mm and 2-10 mm particle sizes was 40%, and was 60% for 10-20 mm and 20-40 mm particle size of spoil. Adding more than the optimal ratio of dress-soil caused little more amelioration effects of limestone spoil, and economic and ecological benefits were low.
[Conclusions]
By this study we obtained the soil water properties and growth of tall fescue in different particle size limestone spoil mixed with dress-soil, the research methods and results may provide a reference for mine spoil utilization and ecological restoration. We should focus on the influence in the ameliorating process of different rock types, mineral composition, weathering degree and salt content in the further research on the improvement of mine waste rocks.
2017 Vol. 15 (3): 114-122 [
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559
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556
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123
HUANG Yuhui, ZHANG Weiqiang, GAN Xianhua, TANG Honghui, PAN Lijun, XIAN Weiguang
Soil quality assessment on different tree species composition patterns in
Cunninghamia lanceolata
stand conversion in south subtropics
[Background]
The productivity and soil quality of
Cunninghamia lanceolata
plantation continuously decreased by managements of pure and successive plantation, short rotation, and clear-cutting harvest, which were harmful to forest sustainable development. In order to improve forest ecosystem productivity and soil quality,
C. lanceolata
and broadleaf mixed plantations (hereafter referred as mixed plantations) were established by planting different broadleaf tree species at the clear-cutting site of
C. lanceolata
plantations in south subtropics of China.
[Methods]
Taking soil chemical property of a 13-year-old pure
C. lanceolata
plantation as control, we studied the influence of tree species composition on soil characteristics at top 25 cm depth in 12 mixed plantations of 11-12 years old. We compared the differences of soil physical (bulk density, soil water content, total porosity, capillary and non-capillary porosity, and particle components) and chemical (pH, soil organic matter, total N, total P, available N, NH
4
+
-N, NO
3
-
-N and available P content) properties, as well as microbial biomass carbon and nitrogen content among 12 mixed plantations. Integrated soil quality index of each mixed plantation was calculated on the basis of principal component analysis.
[Results]
The results showed that the pH (4.15-4.71), available N (81.4-152.8 mg/kg) and available P (0.93-2.39 mg/kg) of mixed plantations were higher than those of pure
C. lanceolata
plantation (4.06 for pH, 30.8 mg/kg for available N and 0.76 mg/kg for available P, respectively). In contrast, the total P content of pure
C. lanceolata
plantation (0.34 g/kg) was higher than those of most mixed plantations (0.14-0.32 g/kg) except plantation C (0.45 g/kg). There were no consistent trends among different plantations for other soil property indexes. Soil quality index of mixed plantations varied from 0.25 to 0.64, which was higher than 0.6 in three kinds of tree species composition pattern, including 1)
Mytilaria laosensis + Cinnamomum camphora + Cinnamomum burmanni + Michelia macclurei + C. lanceolata, 2) M. laosensis + Liquidambar formosana + C. camphora + Winchia calophylla + C. lanceolata
,and
3) M. laosensis + L. formosana + C. camphora + Elaeocarpus sylvestris + C. lanceolata
, indicating greater ability on improving soil quality than other species composition patterns.
[Conclusions]
M. laosensis
and
C. camphora
could be much more helpful to improve soil quality than other species, while
Syzygium hainanense
and
Lagerstroemia speciosa
had no apparent effect. The three kinds of tree species composition pattern mentioned above should be appropriate in conversion of pure
C. lanceolata
plantation in south subtropics of China. The future study of stand conversion should be focused on the interspecific relationship, proportion of advantaged tree species, and density in mixed plantations.
2017 Vol. 15 (3): 123-130 [
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400
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578
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131
LIU Yongjie, HU Zhenhua, LIU Yongbing, LI Xiang, WANG Jiajia, LUO Nan, HONG Wenliang
Fertility, heavy metal pollution characteristics of river sediment and the risk assessment in Hainan Island
[Background]
It is pointed in the governmental document of "
Water Pollution Control Action Plan
" that the water sediment after dredging and disposal, could directly eliminate the phenomenon of black smelly water. The dredged sediment utilization is the main way of land use, ecological restoration materials, construction materials, sewage treatment, etc. Hainan is a unique volcanic tropical island in China, nutrients and heavy metals in sediments formed by unique soil parent material have become the academic research priorities, and the reuse of river sediment can solve the problem of insufficient exogenous soil in land ecological remediation project. Characterization and evaluation is an important prerequisite for sediment resource utilization. In order to understand the characteristics of river sediment in the tropical basalt area of Hainan Island and the possibility of resource utilization, comprehensive and detailed understanding of river sediment heavy metal pollution status, nutrient level and ecological risk, for the river sediment dredging and subsequent resource disposal, is of great significance.
[Methods]
The typical river pond Tangliutang was selected as the research object, and the typical section distribution point in August 2015 was used. The heavy metals and fertility of 52 sediment samples were tested and evaluated by different evaluation methods. Data was statistically processed by SPSS 22.
[Results]
1) According to the index of soil nutrient grading in the second national soil survey, the total nitrogen content in the sediment reached grade Ⅰ, the contents of total phosphorus, total potassium and organic matter were in grade Ⅱ, and the CEC (Cation Exchange Capacity) reached grade Ⅳ. The gray relational index of each fertility index was higher than that in the control area, which indicated that the nutrient of river sediment was fine. 2) Standard "
Environmental Quality Evaluation Standards for Farmland of Edible Agricultural Products
" (HJ 332-2006) was used to evaluate the heavy metal pollution of the sediment. The main pollutants were Cd and Hg, Cd exceeded the standard by 14% with 65.4% samples, and Hg exceeded the standard by 11% with 59.6% samples. 3) The evaluation results of geo-accumulative pollution index and comprehensive geo-accumulative pollution index (I
cgeo
) showed that the main pollutants in the river sediment were Cd and Hg, while the river sediment was moderate pollution. 4) The evaluation of potential ecological risk index showed that Hg was the most important potential ecological risk factor. The sediment was at the level of "slight ecological hazard" according to comprehensive potential ecological risk index
E
RI
.
[Conclusions]
Under the situation of above results. Whether or not the sediment can be applied in land reuse is up to each practical case, for instance, it can be used for forest restoration but not for rice planting. This study provides a scientific basis and technical support for the ecological reconstruction and soil resource utilization of dredged sediment in the major land rehabilitation project of Nandu River ndu River in Hainan Province.
2017 Vol. 15 (3): 131-138 [
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546
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139
QIU Jin'an, LIU Xilin
Status and comprehensive analysis of
benggang
research in China based on knowledge maps
[Background]
Benggang
is an erosion gully, which widely distributes in the tropical and subtropical granite-covered areas of southern China, generally composed of hillslope, headwall, colluvium, gully, and alluvial fan affecting by water and gravity. It has a serious threat on the local security of ecology, food, flood control and living security.
[Methods]
In order to review the development process of
benggang
research in China in the past half century, this paper used the CNKI (
China National Knowledge Infrastructure
) database as the data source to statistically analyze the number, annual growth rate and published journals of
benggang
research papers in 1966-2016. Based on CiteSpace, the knowledge maps of
benggang
research were excavated and analyzed visually, and the core author group, main research institutions and high frequency keywords were identified.
[Results]
1) The number of papers about
benggang
research published in China between 1966 and 2016 showed a fluctuating trend. 2) The published journals of
benggang
research were mainly related to the disciplines of soil and water conservation, reflecting the interdisciplinary research need to be strengthened. The overall impact factors of these published journals were relatively low, reflecting that the level of
benggang
research needs to be improved. 3) There were few academic exchanges among research institutions, and their scientific research strength differed significantly. Therefore, the exchanges and cooperation between the research teams need to be enhanced to achieve common development. 4) "
Benggang
", "
benggang
erosion", "soil erosion", " water and soil loss", "hillslope", "weathered crust" and so on were the main keywords of
benggang
research in China. "Colluvium" and "shear strength" were the hot spots of
benggang
research in recent years. The most published papers of
benggang
research were related to the prevention and control measures, while quantitative researches were scarce.
[Conclusions]
Through the visual excavation and analysis of knowledge maps of
benggang
research, it is conducive to scientific researchers to have a more comprehensive, objective and accurate understanding on the history and current situation of
benggang
research in China, so as to better refine the research direction, and provide more in-depth specific guidance.
2017 Vol. 15 (3): 139-148 [
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