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2019 Vol.17 No.1
Published 2019-02-28
1
GUO Luomin, LI Xiaoli, WANG Wen, ZHANG Ying, CHANG Ping
Influence of slope on the splash erosion of mauve Pisha-sandstone in bare areas
[Background]
Understanding the mechanism of splash erosion is of great significance to establish the rainfall erosion model of Pisha-sandstone. This paper is to study the splash erosion mechanism of the Pisha-sandstone in the bare area of the Ordos Zhungeqi area, the southern Inner Mongolia of China.
[Methods]
This study used the rainfall simulator to perform the splash erosion experiment. It designed 5 different rainfall kinetic energies (7.15,9.14,10.21,14.24, and 16.22 J/(m
2
·mm)) and 6 different slopes (5°, 10°, 15°, 20°, 25° and 30°), to explore the changing on the quality of splash erosion on uphill and downhill and the amount change of total splash erosion and net splash erosion. Based on the theory of mechanics and geometry, the impact causes of slope change on splash erosion were analyzed.
[Results]
1)Under the same rainfall conditions, splash erosion on uphill decreased with the increase of slope. At same time, the splash erosion on downhill showed the trend of increasing first and then decreasing with the increase of slope, then there was a critical slope where there was a maximum splash erosion from the downhill, it was 25°. 2) There was an exponential function between the amount of the splash erosion and the rainfall kinetic energy, and the coefficient term of the exponential function was a trigonometric function of slope. 3) From the geometric point of view, the variation of the slope gradient resulted in the change of the maximum migration distance to the migrating particles in different directions. 4) The change of the component of rainfall kinetic energy along the horizontal and normal directions of the soil's surface was the important reason of critical slopes occuring. 5) The total splash erosion did not show obvious regularity with the change of slope. The variation of net splash erosion with slope was similar to that of downhill.
[Conclusions]
This study provides a theoretical basis for further study of the hydraulic erosion mechanism of Pisha-sandstone.
2019 Vol. 17 (1): 1-9 [
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10
CHAI Yafan, ZHOU Bo, LÜ Wenqiang, WU Yufeng
Erosion process and infiltration features of red soil slumping slope sediment under artificial simulated rainfall condition
[Background]
Erosion of red soil is one of the serious forms of soil erosion in the gully region of the Loess Plateau. However, the erosion characteristics of the sloping erosion and the infiltration of the slope are not studied in depth. It is of great significance to further explore its erosion process and permeability for preventing the erosion of red soil.
[Methods]
Test materials from the shady slope and the sunny slope of Tianjiagou watershed in Gansu province were collected, and filled into the experimental trough tank at 10 degree as similar to natural dump status as possible. Four rainfall intensities of 16.1, 29.3, 40.5, and 51.3 mm/h were set by simulated artificial rainfall Norton 8100 from USA, 3 times of experiment were repeated for each rainfall intensity, thus total 12 experiments were conducted. Runoff period, rainfall duration, runoff yield, average runoff rate, runoff coefficient, sediment yield, average sediment rate, and infiltration rate were recorded and calculated. The data was processed by Excel 2007.
[Results]
For the erosion process of the red soil slumping slope sediment, the total runoff generated under 4 rainfall intensities (16.1, 29.3, 40.5, and 51.3 mm/h) was 2 250, 5 174, 10 036, and 17 612 cm
3
, respectively. The total amount of sediment production increased gradually from 290 g (in 16.1 mm/h) to 810 g (in 51.3 mm/h),which expressed as follows 290 g (in 16.1 mm/h) < 620 g (in 29.3 mm/h) < 780 g (in 40.5 mm/h) < 810 g (in 51.3 mm/h).The time required for reaching peak sediment was shortened from 26 min to 16 min, which were 26, 20, 18 and 16 min, respectively. The time required for sediment reaching stabilization in the runoff showed similar changes with the time required for reaching peak sediment,which were 34, 32, 30 and 26 min, respectively, and the average infiltration rates were 0.22, 0.37, 0.44, and 0.45 mm/min, respectively, and steady infiltration rates gradually increased,and appeared as from 0.19 to 0.39 mm/min.
[Conclusions]
As rainfall intensity increases, the runoff, sediment yield, and infiltration rate under different rainfall intensity of the red soil slumping slope sediment increase gradually, while the trend of increasing the rate of steady infiltration is not obvious, and the time required for stable production and sediment production is gradually shortened. In addition to this, the conclusions of this study may provide guidance for the prevention and control of erosive erosion and improvement of the red soil slumping slope sediment.
2019 Vol. 17 (1): 10-15 [
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16
YANG Weige, DAI Ru, ZHANG Yan, LI Meilan, GONG Wei
Analysis of variations and causes in runoff and sediment of Yangtze River during 2000-2015
[Background]
The study on the change of runoff and sediment in the Yangtze River and its causes can provide theoretical basis for mastering the evolution law of runoff and sediment of the Yangtze River.
[Methods]
Based on the measured data of runoff and sediment of Yangtze River's seven major hydrologic stations (Pingshan, Zhuotuo, Cuntan, Yichang, Shashi, Hankou and Datong) and using statistical methods and the double accumulated method, this paper analyzed the changes characteristic and causes of runoff and sediment in Yangtze River during 2000 to 2015.
[Results]
The result showed that the volume of runoff and sediment load of Yangtze River's seven major hydrologic stations decreased. Meanwhile, the volume of runoff did not change significantly, but the sediment runoff changed in a large range. The proportion of the runoff volume of the station in the upper Yangzer River sites in Datong station was small, while the proportion of sediment transport was larger. It indicated that the sediment of the Yangtze River was mainly from the upstream region. There was a significant positive correlation between annual runoff and sediment transport in the sever station site of the Yangzer River. But the correlation coefficient of runoff and sediment transport in Pingshan station was relatively high (
R
2
=0.67), and the correlation coefficients of other stations were low. The double mass curve of Pingshan, Zhuotuo and Cuntan had an obvious turning point in 2010 and 2012, which showed that the sediment load was decreased significantly in the upper Yangtze River the from 2012. The double mass curves of Yichang, Hankou and Datong station had an obvious turning point in 2002 and 2005. The slope was reduced after the turning point which showed that the sediment load was decreased significantly in the middle and lower reaches of Yangtze River from 2002. Moreover, The turning point of Shashi station was in 2002 and 2007 and the amount of sediment has been a certain degree of control after 2007 in Shashi hydrologic station. The annual runoff in the Yangtze River basin from 2000 to 2015 year has not changed significantly, and the trend of runoff and annual rainfall was consistent. The Sediment discharge was on a downward trend, the change trend of the annual precipitation and sediment from 2003 to 2009 was poor consistency, which showed that the precipitation had little impact on the sediment concentration between 2000 and 2015 in the Yangtze River. The reservoir sediment, the soil and water conservation engineering and other human activities are the main reasons that cause Yangtze River's relations of water and sediment changing obviously since 2000.
[Conclusions]
This research could provide the theoretical basis for the protection of the Yangtze River.
2019 Vol. 17 (1): 16-23 [
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24
BO Shengnan, WANG Yunqi, MA Chao, LI Yaguang
Quantified effects of fixing soil by root system of
Broussonetia papyrifera
based on experiment and model
[Background]
Roots of vegetation play an important role in slope stability, and increase soil strength. To study and quantify the effect of the root system on soil reinforcement, taking the
Broussonetia papyrifera
as the research object, the reinforcement effect of the root system of the
B. papyrifera
was determined by two methods of experimental determination and model calculation.
[Methods]
We used root-soil samples of
B. papyrifera
with different root diameters and volumes, and measured the pull strength of root-soil samples. Direct shear instrument was used to determine the shear strength of the root-soil and soil blocks. Wu model was to calculate the root shear strength increment of the root-soil samples. Compared measured values with the calculated values by Wu model, the effect of the diameter and the number of roots on the increment of shear strength were analyzed.
[Results]
1) The tensile strength and pull strength of
B. papyrifera
root decreased with the increase of diameter. Two strengths intersected at a diameter of 1.3 mm. The root's pull strength was greater than the tensile strength when the diameter was < 1.3 mm; the tensile strength was higher than the pull strength when the root system was > 1.3 mm. 2) The results of the direct shear test showed that when the positive pressure on the shear surface was smaller, the shear strength of the soil-root blocks increased with the increase of the root diameter and the number of roots. As the positive pressure increased, the relationship between the shear strength and root diameter and the number of roots was no longer a simple incremental relationship. The maximum shear strength of root-soil complexes with the same number of roots migrated toward the smaller diameter of the average root diameter. 3) Wu model overestimated the effect of roots on soil reinforcement, and high valuation increased as the number of roots and root diameter increases.
[Conclusions]
There is a threshold between the tensile strength and the pull strength, and it is 1.3 mm. Under a certain range of root cross-sectional area ratio, the influence of the increase in shear strength of smaller diameter roots is more significant than the number of roots. For soil of Jiufeng and the root of
B. papyrifera
, we revised the
k
' value as 0.45. In addition, how to improve the simulation accuracy of the model and explore the numerical model of strength suitable for the failure of different plant roots is still a direction in this field.
2019 Vol. 17 (1): 24-30 [
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412
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362
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31
ZHANG Lina, XU Li, QIN Ru, SHI Ruijia, YANG Yuping
Evaluation of water conservation capacity of three shrub forests based on fuzzy matter-element model: A case study of Heidaigou open pit mine dump in Inner Mongolia
[Background]
The water-holding capacity of litter layer and soil layer of forest land is an important indicator of soil and water conservation function of forest land, and they are two important indexes to evaluate the capacity of water conservation. There has been no reported literature on the water conservation function of typical shrubbery in Heidaigou mining area yet. In recent years, the evaluation of water conservation capacity based on fuzzy matter-element model is considered as a simple, direct and scientific method. Therefore, fuzzy matter-element model was used to evaluate the water-holding capacity of litter layer and soil layer of forest land in Heidaigou of Inner Mongolia.
[Methods]
This study took the litter and soil under shrub forest of
Caragana korshinskii
,
Sabina vulgaris
and
Prunus armeniaca
of artificial planting 15 years as the research object on the same platform of dump in Heidaigou open pit mine. The methods of soaking, drying and cutting-ring were used to study the accumulation of litter, water-holding characteristics of litter, physical properties of soil and water-holding characteristics of soil. Fifteen indexes affecting litter and soil water-holding capacity were selected to establish the evaluation index system of water conservation capacity of three kinds of shrub forest. The fuzzy matter-element model of Euclid approach degree was used to evaluate the water conservation capacity of three shrubs.
[Results]
The species composition and growth status of shrub vegetation were different, which resulted in great differences in the thickness of litter, the amount of storage and the characteristics of water-holding under the forest. And the variation ranges of litter thickness and the amount of storage of three shrub types were 0.83-1.08 cm and 2.42-3.82 t/hm
2
, respectively. The index values of water-holding characteristics of litter layer were the largest in
S. vulgaris
shrub, especially maximum water-holding capacity and effective interception rate. Soil development affected bulk density and porosity of soil, which led to differences in soil physical properties. The soil bulk density of three shrub types showed the rule of
C. korshinskii
(1.50 g/cm
3
) >
S. vulgaris
(1.44 g/cm
3
) >
P. armeniaca
(1.43 g/cm
3
).The variation law of soil porosity in three shrubs was consistent with that of corresponding water content. In addition to soil bulk density, non-capillary porosity and effective water-holding capacity, the index values of the soil layer were also the best in
S. vulgaris
shrub. The order of Euclid approach degree of three shrubs was
R
Sabina vulgaris
>
R
Prunus armeniaca
>
R
Caragana korshinskii
.
[Conclusions]
The order of water conservation capacity of litter layer in three kinds of shrub forest was
S. vulgaris
>
C. korshinskii
>
P. armeniaca
. The order of water conservation ability of soil layer in three kinds of shrub forest was
S. vulgaris
>
P. armeniaca
>
C. korshinskii
. The order of Euclid approach degree of three kinds of shrubs was
S. vulgaris
(0.869 3) >
P. armeniaca
(0.202 7) >
C. korshinskii
(0.151 8), the water conservation capacity of
S. vulgaris
in the study area was the strongest, followed by
P. armeniaca
shrub, and that of
C. korshinskii
was poor.
2019 Vol. 17 (1): 31-38 [
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434
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39
YIN Xiaoai, ZHOU Yunchao, YE Lipeng
Nutrient-planting density coupling effect in the root growth of
Pinus massoniana
seedlings
[Background]
Root system plays key role in soil and water conservation, while coupling effect of planting density and soil nutrient on the root growth of plant remains unclear.
Pinus massoniana
is a dominant tree species in Guizhou province, and thus selected as study material in this study. This work aims to clarify 2 questions:1) the response mechanism of
P. massoniana
seedlings roots to planting density and soil nutrients; and 2) the mechanism or effect of planting density-nutrient coupling among roots of
P. massoniana
seedlings.
[Methods]
The pot experiment was carried out in this study, 6 planting densities (1-6 Trees/pot) and 6 soil types (A
0
-A
5
) were set to explore the growth of
P. massoniana
roots, A0-A5 consisted of different ratio of layer A (leaching layer) and layer B (deposition layer), and their nutrients were in order:A
0
< A
1
< A
2
< A
3
< A
4
< A
5
. Root morphology indexes, including root length, root surface area, root volume, and root biomass, were analyzed by Expression 10000XL 1.0 and Win RHIZOC Pro 2004b, and the data were processed using Microsoft Excel 2013 and SPSS 20.0 software.
[Results]
Root surface area, root length, root volume and root biomass increased with the increase of soil nutrient, and were the maximum at planting density of 1 tree/pot. The total root length in the planting density 1 tree/pot was higher than that in planting density 6 trees/pot 30.7% (A
0
), 64.5% (A
1
), 51.2% (A
2
), 67.3% (A
3
), 54.7% (A
4
) and 72.2% (A
5
). The total root volume in planting density 1 tree/pot was higher than that in 6 trees/pot by 57.2% (A
0
), 55.3% (A
1
) than, 74.1% (A
2
), 47.2% (A
3
), 51.2% (A
4
) and 65.2% (A
5
). The competition intensity of roots in different soil nutrients showed as middle nutrient > high nutrient > low nutrient, and each nutrient had the highest competition index at planting density 6 trees/pot by 0.502 (A
0
), 0.641 (A
1
), 0.737 (A
2
), 0.623 (A
3
), 0.753 (A
4
) and 0.629 (A
5
). The correlation coefficient between total root length and soil nutrients was the largest (
R
2
=0.945). Planting density had a greater impact on root growth than soil nutrients in the coupling effect of soil nutrient and planting density. There was a binary functional relationship between the two and the root system. The soil nutrient was positively correlated with root growth, and the positive correlation coefficient ranged in 0.044 and 1.436. The planting density was negatively correlated with root growth, and the negative correlation coefficient was in (-34.757) and (-1.901).
[Conclusions]
Under medium and medium planting density conditions, medium soil nutrient is more suitable for root growth of
P. massoniana
. There are other interactions between the roots of adjacent plants, which are hypothesized as inhibitory effects, the results of plant roots inhibiting the growth of adjacent roots. Increased soil nutrients weaken competition between roots, and increased planting density increases competition among roots. The binary density function can be used to explain the planting density and nutrient conditions suitable for root growth of
P. massoniana
.
2019 Vol. 17 (1): 39-47 [
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48
SUN Yubo, BI Huaxing, DUAN Hangqi, PENG Ruidong, WANG Jingjing
Fine-root morphological variation and below-ground competition of an apple-peanut intercropping system
[Background]
Apple-peanut intercropping system is one of the major agroforestry systems on the Loess Plateau of China. However, the extensive management practices for apple-peanut intercropping system leads to intense competition among species for below-ground resources, which results in low overall economic efficiency. To alleviate the interspecific below-ground competition of apple-peanut intercropping system, a scientific basis and technical support for management practices should be investigated.
[Methods]
A stratified excavation method was performed both to explore the variation of fine-root morphological variation and to quantify the interspecific below-ground competition status of apple-peanut intercropping system and monocropping systems. Among them, the apple trees were planted for 7 years, and the planting densities of apple trees and peanuts were 500 and 83 333 plants/hm
2
, respectively. Peanut was cultivated at a distance of 0.5 m from the apple tree row. The area within 0.5 m of the apple tree row was used for fine-root sampling (4.0 m×4.0 m) in both the apple-peanut intercropping system and monocropped apple treatments. Three sections (4.0 m×0.4 m) were randomly selected as the fine-root sampling area in the monocropped peanut treatment. Fine-root dry weight was measured by sampling, while fine-root biomass density, fine-root vertical barycenter and below-ground interspecific competition intensity index were calculated.
[Results]
1) The fine roots of apple trees were mainly distributed within 1.7 m from the apple tree row. The farther the section was to the apple tree row, the less the fine-root mass density of the apple trees, while the more the fine-root mass density of the intercropped peanut. The fine-root mass density of both apple trees and intercropped peanut of the northern apple tree row was greater than that of the southern, and the fine-root biomass density of the intercropped apple trees and intercropped peanut were less than that of the monocropping systems. 2) The fine roots of apple trees concentrated mostly within the soil depths of 0-60 cm, and those of apple trees and peanut were distributed mostly within the 20-40 cm and 0-20 cm soil depth, respectively. Compared with that in the monocropping systems, the fine-root mass density of the intercropped apple trees and peanut decreased in each soil layer. 3) Compared with that of the monocropping systems, the fine-root vertical barycenter of the intercropped apple trees displaced deeper soil, and the fine-root vertical barycenter of the peanut displaced shallower soil; the fine-root vertical barycenter of both apple trees and peanut displaced deeper soil with distance from the apple tree row. 4) The components of the apple-peanut intercropping system competed for soil water and nutrients at distances 0.5-2.5 m from the apple tree row. The interspecific below-ground competition intensity was slightly greater in the south of a apple tree row than the north of a row. The interspecific below-ground competition index of the apple-peanut intercropping system in the 0.5-1.7 m area of apple trees was greater than 0.53, which was the main area of interspecific below-ground competition. And a relatively greater intensity of below-ground interspecific competition in the apple-peanut intercropping system for soil water and nutrients occurred within distances of 0.5-1.7 m from the apple tree row.
[Conclusions]
To effectively alleviate the below-ground interspecific competition in apple-peanut intercropping system and obtain more production, farmers should appropriately increase the distance between peanut and apple tree rows. Peanut should be planted in areas at distances of 1.7 m away from apple tree rows. Furthermore, farmers should also increase water and fertilizer input within the 0-20 cm soil layer in intercropping area. Irrigation and fertilization can be appropriately increased with the distance from the apple tree row; in addition, input in the south side of an apple tree row should be slightly greater than those in the north side of the row.
2019 Vol. 17 (1): 48-56 [
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57
WANG Shan, SHAN Lishan, ZHANG Zhengzhong, SU Ming, LI Yi, BAI Lei
Effects of precipitation on seed germination and seedling emergence of
Reaumuria soongarica
[Background]
In temperate deserts of China,
Reaumuria soongarica
is one of the dominant species. This study aim to explore the response of seed germination and emergence to precipitation patterns. Which would provide a scientific basis for further study of the response characteristics of typical desert plants under the background of global climate change.
[Methods]
The experiment,under artificial control conditions,were composed by two parts:1) 2 water absorption and 4 drought time gradients,2) 5 precipitation gradients and 6 precipitation frequencies.
[Results]
1)The seed germination of
R.soongarica
was significantly affected by the duration of drought (
P
<0.01). Compared with the control,the germination rate of
R.soongarica
seeds with water absorption (1 d or 2 d) was significantly increased after short-term drought (1 d,2 d and 4 d). The germination rate would decrease after a long-term drought (8 d). 2)Seedling emergence of
R.soongarica
was significantly affected by precipitation quantity and precipitation frequency (
P
<0.01). The emergence rate was increased with the increase of precipitation frequency. When the precipitation rate quantity is 30 times/month and precipitation frequency is 100 mm,the emergence rate is the highest. 3)The length of radicle and the duration of drought had significant effects on the ability of seedlings to regain growth after rewatering (
P
<0.01). The ability of seedlings to regain growth after rewatering decreased with the increase of radicle length before drought. Under the same radicle length, prolonging the drought time will reduce the ability of seedlings to resume growth after rehydration.
[Conclusions]
The optimal precipitation of
R.soongarica
seedlings is 100 mm, and the best precipitation frequency is 30 times/month. The changes of precipitation quantity and precipitation frequency caused by climate change will significantly affect the regeneration of
R.soongarica
seedlings.
2019 Vol. 17 (1): 57-63 [
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442
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373
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64
JIANG Song, MENG Jijun, CHEN Yiyun
Analysis of hydrological effects of land use and landscape pattern in the middle reaches of Heihe River
[Background]
Regional land use and the pattern of landscape have an important influence on hydrological effects. Previous studies on the influence mechanism of water yield focused on the land use area, but take little consideration about landscape pattern.
[Methods]
This study was conducted in the middle reaches of Heihe River, which locates in the arid area of Northwest China. Based on the land use data (2000, 2010, and 2014), climate data (1999-2015) and basic geographic information data, this study established InVEST model to simulate the water yield. On the scale of land use, considering the spatial factors, this study analyzed the effects of land use types on water yield by means of ordinary least squares regression model, spatial regression model and geographically weighted regression model. On the scale of landscape, combining principal component analysis to screen landscape index, this study further analyzed the effects of landscape pattern on water yield.
[Results]
1) The middle reaches of Heihe River had more water yield in the southeast, less in the northwest, and the water yield in 2000, 2010, and 2014 was 1.73×10
8
m
3
、1.63×10
8
m
3
、1.38×10
8
m
3
respectively. 2) On the scale of land use, the regression coefficients of wood land, water and farmland were all greater than 0, and the coefficients of construction land and bare land were all less than 0. On the scale of landscape, the regression coefficient of the first principal component which was mainly explained by landscape richness and evenness was greater than 0, and the coefficient of the second principal component explained by area standard deviation was less than 0. Water yield is promoted in wood land, water and farmland, but reduced in construction land and bare land. 3) The Moran's I of residual of ordinary least squares regression model and spatial error model was -0.43 (
P
=0.03), 0.12 (
P
=0.11) respectively. The
R
2
of ordinary least squares regression model, spatial regression model and geographically weighted regression model was 0.59, 0.71, 0.90 respectively. On landscape scale, the more abundant the landscape types, the more evenly the patches distribute, the more conducive to water yield, while conversely, water yield is suppressed. The spatial regression model eliminates the negative spatial correlation of regression residuals. Geographically weighted regression improves the model performance.
[Conclusions]
The middle reaches of Heihe River have a decreasing trend with the increase of the year, which is directly related to the change of local land use and landscape pattern. These results may provide reference for regional ecosystem management.
2019 Vol. 17 (1): 64-73 [
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496
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1336KB] (
384
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74
LI Zhiguang, XU Yongli, WANG Yongsheng
Contents and assessment methods of water and soil conservation target responsibility
[Background]
The state attaches great importance to ecological civilization construction, and assessment methods for ecological civilization construction goals have been issued. As important content of ecological civilization construction, the implementation of the target responsibility system for soil and water conservation and the reward and punishment system for assessment are not universal.
[Methods]
By analyzing the list of responsibilities stipulated in the soil and water conservation law of the People's Republic of China, this paper further clarified the indexes, constructed a legal system of target responsibility for soil and water conservation, and put forward a comprehensive evaluation method.
[Results]
The index system includes the leading organizations, the construction and implementation of rules and regulations, the formulation of soil and water conservation planning, the prevention and implementation of soil erosion, the management and implementation of soil erosion, the supervision of law enforcement and monitoring and evaluation of soil and water conservation, a total of 7 kinds of soil and water conservation target responsibility, as well as the 48 indicators to reflect these responsibilities. Based on the index system, the comprehensive evaluation model of objective responsibility (LZZS) was established, and the application process of "series" and "parallel" models was put forward, and the suggestions for the application and development of the model were also proposed.
[Conclusions]
This paper can provide a reference for local governments at all levels to establish goals and responsibilities for soil and water conservation, reward and punishment systems for assessment, to comprehensively and effectively promote the prevention and control of soil erosion and to promote the construction of ecological civilization.
2019 Vol. 17 (1): 74-81 [
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446
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814KB] (
685
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82
LI Yuanhang, HE Kangning, ZHANG Tan, ZHANG Zhenzhong, YIN Baosi, LIN Sha, WANG Li
Effects of salt stress on the photosynthetic and physiological indexes of
Lycium ruthenicum
[Background]
The Qaidam Basin is one of the most serious land salinization areas in China, especially secondary salinization, which not only has serious impacts on the survival of local residents and agricultural development, but also hinders the construction of ecological environment. Recently, the nutrients, trace elements, polysaccharides and pigments of
Lycium ruthenicum
have mainly been analyzed by scholars, but the ecological benefits have been less investigated, especially stress resistance. At present, the research area is mainly concentrated in Ningxia,there is very little research on the Qaidam area,especially secondary saline land.Therefore, it is importment to determine the resistance of
L. ruthenicum
and to explore its salt tolerance mechanism, which is essential to improve the ecological security and economic benefits of the Qaidam Basin.
[Methods]
1-year-old
L. ruthenicum
seedlings were used for pot comparison test in Nuomuhong Farm on the southeastern edge of the Qaidam Basin. Salt stress environment was simulated using salt solution concentration gradients of 0,50,100,200 and 400 mmol/L, there were 3 repeats in each gradient, thus totally 15 pots. Through the weighing method, soil was controlled in the amount of water as 75%±0.3% of the field water capacity. The growth trend, photosynthetic characteristics, and chlorophyll fluorescence characteristics of the
L. ruthenicum
were measured by Meter ruler,Licor-6400,handy PEA chlorophyll fluorescence instrument, and spectrophotometer respectively under salt stress. Data were analyzed according to ANOVA by SPSS statistical software and the significant differences among means were identified by Duncan's multiple range tests at a significance level of
P
<0.05, and all data were presented as mean ±SE.
[Results]
1) High concentrations (100-400 mmol/L) of salt stress significantly decreased plant height increment, chlorophyll content, and maximum fluorescence yield (
F
m
). 2) The net photosynthetic rate (
P
n
), stomatal conductance (
G
s
), transpiration rate (
T
r
) and maximum photochemical efficiency (
F
v
/
F
m
) of the plants significantly reduced when the salt concentration was >100 mmol/L. These indicators were elevated but not so significant when the salt concentration was 50 mmol/L. 3) When the salt concentration was 400 mmol/L, the
F
o
decreased significantly. 4) Low concentration of salt stress (50-100 mmol/L) decreased the
C
i
. When the salt concentration exceeded 200 mmol/L,
C
i
increased significantly.
[Conclusions]
In a summary, the chlorophyll content and photosynthetic physiological indicators of
L. ruthenicum
seedlings significantly reduced under high salt stress, which ultimately led to the inhibition of plant growth. At this time,non-stomatal limitation and inactivation of photochemical activity were the main factors affecting photosynthesis. Under low concentration of salt stress,the physiological growth indicators of
L. ruthenicum
did not change significantly, exhibiting a certain degree of salt tolerance.
2019 Vol. 17 (1): 82-88 [
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432
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386
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89
HUANG Tongli, TANG Lixia, CHEN Long, ZHANG Qiaoyan
Root architecture and ecological adaptation strategy of three shrubs in karst area
[Background]
Ecological environment in the karst area is very fragile and the soil erosion is serious.Plant roots play an important role in controlling shallow landslides, consolidating soils, and preventing soil erosion.Root architecture is one of the important factors affecting the function of soil fixation. Therefore, studying the unique root architecture of shrubs in this area is of great significance for evaluating the soil and water conservation effects of plant roots.
[Methods]
In this study,the whole plant root system was excavated by stepwise mining, and the diameter, height, crown width, root diameter, root length and root angle were measured. The topological index, root connection length and root branching rate of three shrub roots in Karst area of central Guizhou were analyzed, and the horizontal distribution characteristics and root bending characteristics of roots were discussed.
[Results]
1)The three shrubs adopt similar adaptive strategies to the limited living space of karst, and the topological index
TI
is close to 1, that is, they all tend to the herringbone structure. 2)The total root connection length of the three shrubs was longer,which was characterized by
Cassia bicapsularis
(597.17 cm) >
Indigofera amblyantha
(589.23 cm) >
Pyracantha fortuneana
(567.53 cm),but the difference between the species was not significant (
P
>0.05). In addition there was no significant difference between the root connection lengths of the tertiary and fourth roots (
P
>0.05), and there was a extremely significant difference between the root lengths of the other levels (
P
<0.01). 3)The total root branching rate of
Pyracantha fortuneana
(2.314) >
Indigofera amblyantha
(1.747) >
Cassia bicapsularis
(1.541), that is, the root branching ability of Pyracantha spinosa was the strongest. 4)The root systems of three shrubs distribute unevenly in horizontal direction, and there is uncertainty. In addition, shrub roots also exhibit a unique entangled and curved shape in the search for growth space.
[Conclusions]
In order to adapt to the karst fragile habitat, the shrub root system adopts the development of the herringbone structure, increases the length of root connection, reduces the branching rate of the root system, and grows in a curved winding manner, and the root system is unevenly distributed horizontally and is explored by the external habitat and the root itself. The common impact of the mechanism.
2019 Vol. 17 (1): 89-94 [
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495
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95
LIU Xinchun, ZHAO Yonggang, LIU Xiaofang, ZHU Xingfei, GAO Ran, LI Wenyu
Distribution of moisture storage and fine root biomass in deep soil layers under typical artificial vegetation during the growing season in the Loess Plateau of western Shanxi, China
[Background]
The Loess Plateau of western Shanxi is one of China's most degraded land regions with serious soil erosion. Since the Grain-for-Green Program was implemented in this region, a growing number of exotic trees have been introduced by human activities. Due to their strong water consumption via deep roots, the contradiction between vegetation water demand and soil water supply has become increasingly prominent. Currently, there is a lack of research linking the characteristics of deep (>2 m) soil moisture storage (SMS) and fine root distribution in the Plateau. This study analyzed the distribution of SMS and fine root biomass (FRB), and assessed their relationship under typical artificial vegetation types during the growing season in western Shanxi of the Loess Plateau.
[Methods]
Four artificial vegetation types (
Medicago sativa, Robinia pseudoacacia, Platycladus orientalis
, and
Juglans regia
) were selected from the study region, with long-term cropland as the control. Soil and root samples were taken from depths of 0-500 cm at 10 or 20 cm intervals. SMS was derived from soil moisture content that was measured based on oven-drying at 105-110℃, while FRB (<2 mm) was measured after drying at 80℃ to constant weight. Differences among the treatments in deep layers were examined for SMS and FRB by one-way analysis of variance. The relationship between SMS and FRB in each deep layer was analyzed using Pearson's correlation coefficients.
[Results]
Based on the distribution of soil moisture content, the soil profile was divided into 2 layers of shallow (0-70 cm) and deep (70-500 cm); the latter was subdivided into precipitation infiltration layer (70-160 cm), transition layer (160-280 cm), and relatively stable layer (280-500 cm). The SMS in deep layers significantly differed among the 5 treatments (
P
<0.05). Compared with the control, the total deficit of SMS in deep soil profile under artificial vegetation types ranked as
R. pseudoacacia
(-448.25 mm) >
J. regia
(-357.6 mm) >
M. sativa
(-170.83 mm) >
P. orientalis
(-161.93 mm). There were significant negative correlations between FRB and SMS in the infiltration and stable layers (
P
<0.05). The FRB in deep soil profile of all 5 treatments accounted for approximately 37% of the FRB in the total soil profile. The average FRB in deep soil profile decreased in the order
P. orientalis
(2.9 g/m
2
) >
R. pseudoacacia
(2.68 g/m
2
) >
J. regia
(2.67 g/m
2
) >
M. sativa
(1.67 g/m
2
) > control (0.56 g/m
2
).
[Conclusions]
Deep soil moisture was depleted by artificial vegetation and this was closely related to the distribution of FRB in the deep soil profile. The strong linkage between local moisture conditions in the soil and water consumption by plant roots (especially
R. pseudoacacia
and
J. regia
) should be considered during the construction of artificial vegetation in the semi-arid Loess Plateau region.
2019 Vol. 17 (1): 95-101 [
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468
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102
WANG Henian, ZHANG Manyin, CUI Lijuan, YU Xinxiao
Effects of climate change and human activities on streamflow in Haihe mountainous area
[Background]
Climate change and human activity are the major influence factors on streamflow. The effects of climate change and catchment changes on the long-term water balance are of considerable interest at a range of spatial scales. Haihe basin is the most serious and prominent area in China, studying the effects of climate and human activity on streamflow is of great significance for water resources management.
[Methods]
The Budyko framework has been widely used to attribute changes in streamflow to the effects of climate and human activity. And the method of double mass curve (DMC) is often used in the analysis of the consistency of hydro-meteorological factors and their inter-annual variations because a plot of the two cumulative quantities during the same period exhibits a straight line. In this study, we chose the mountainous area of Haihe basin as our study area, and used Budyko hypothesis and double mass curve to analyze the effects of climate and human activity on streamflow.
[Results]
The results show that:1) the precipitation, streamflow and potential evapotranspiration in Haihe basin are all obvious decreased trends, while the temperature is an obvious increased trend; the mann-kendall analysis results show that the streamflow has an abrupt change in 1980; 2) the study period (1957-2000) can be divided into a reference period (1957-1979) and a change period (1980-2000) based on the change point of 1980, the mean streamflow in the reference period and the change period are 115.12 mm and 69.94 mm, respectively, and experiences a large reduction of 45.18 mm; 3)in this change, the effect of climate change were 10.89 mm and accounted for 24.11%, and among them, the effect of precipitation change was decreasing 13.94 mm (accounted for 82.05%) and the effect of potential evapotranspiration was increasing 3.05 mm (accounted for 17.95%); 4) After 1979, human activities began to have a significant effect on watershed streamflow; among the change of streamflow in Haihe basin, the effect of human activities were 33.87 mm and accounted for 74.97%.
[Conclutions]
There are many factors affecting the runoff of the river basin, such as land use change, water conservancy project, water resources development and so on; human activities affect the process of regional water circulation by changing the type of underlying surface, and Haihe Basin is one of the most serious areas affected by human activities. Most studies showed that the effect of human activities on streamflow is far greater than the effect of climate change, and in this study, the results also show that for the changes of streamflow in Haihe mountainous area in 1957-2000, the major factor is human activity and its contribution rate is large as 74.97%, while the contribution rate of climate change is only 24.11%.
2019 Vol. 17 (1): 102-108 [
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346
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523
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109
GUO Qiaoling, MA Zhihua, SU Ning, YANG Yunsong, HAN Zhenying
Effects of cracks in coal mining subsidence area on soil moisture content in Shenfu-Dongsheng coalfield
[Background]
Shenfu-Dongsheng coalfield is an important coal base in China. The occurrence of a large area collapse and a large number of ground cracks reduced soil and water conservation, resulting in soil and water loss. Studying the effect of cracks on soil moisture content in subsidence area of coal mining may provide basic support for controlling soil and water loss and protecting ecological environment.
[Methods]
Taking coal mining subsidence area in Shigetai Coal Mine as the research target, the 52 sampling sites were set up in the 100 m×100 m test area of subsidence area. Then the 7 soil layers, such as 0, 10, 20, 30, 40, 50, and 60 cm depth in each sampling site, were sampled respectively. mathematical statistics were used to analyze the soil moisture content in the cracks (8,4,3,2, and 1 cm), and in the unfractured areas. The spatial variability of soil moisture content in coal mining subsidence area was analyzed by geostatistics and Surfer 11.0.
[Results]
1)In the same depth soil layer, the soil moisture content in the crack area was obviously less than that in the non-crack area. With the increase of crack width the decrease amplitude of soil moisture content was increasing. 2) In vertical distribution, the soil moisture content increased with the increase of soil depth when the crack width ≤ 3 cm. It indicated the moisture content at the relatively deep soil layer was less affected by the narrow crack. The soilmoisture content under the ground 30 cm to 60 cm was obviously less than when the crack width >3 cm, indicating the crack with large width had greater influence on the moisture content at relatively deep soil layer. 3)In horizontal variation of soil moisture content, the low soil moisture content of each soil layer was in the crack development zone. The high soil moisture content of each soil layer was in vegetation covering zone of non-crack area. 4) In vertical variation of soil moisture content, the variation intensity in the soil layers of 0 cm and 40-60 cm in crack zone was greater than that in non-crack zone. The variation intensity in the soil layers of 10-30 cm in crack zone was less than that in non-crack zone.
[Conclusions]
This study proved that the crack in the coal mining subsidence area destroyed soil structure, resulted in the decrease of soil moisture content, affected the spatial distribution of soil moisture, caused soil water loss, and consequently led to ecological degradation.
2019 Vol. 17 (1): 109-116 [
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496
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358
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117
YANG Chuye, WANG Li, SU Fangli, LI Haifu
Characteristics of soil salinity in the distribution area of
Suaeda heteroptera
in Liaohe estuary wetlands
[Background]
The floristic and plant distribution of coastal wetland are significantly affected by soil salinity,
Suaeda heteroptera
, as a typical plant in the Liaohe estuary wetlands of Liaoning province, forms a unique landscape of red beach, which attracts tourists from inland and abroad. However, the area of
S. heteroptera
in Liaohe estuary wetland is decreasing year by year since 2015. Thus it is very urgent for us to protect the
S. heteroptera
with analyzing the main factors of soil salinization and estimating the salinity growth threshold of
S. heteroptera
in Liaohe estuary wetland.
[Methods]
In April 2018, we selected a sample plot in Liaohe estuary wetland with
S. heteroptera
distribution, we chose 3 types of area, junction area of bare beach and
S. heteroptera
, pure
S. heteroptera
growing area, and junction area of
S. heteroptera
and
Phragmites australis
. Soil samples at depths of 0-10 cm, 10-20 cm and 20-30 cm were collected according to the "three-point sampling method". Soil base ion index, Na
+
、K
+
、Ca
2+
、Mg
2+
、Cl
-
、SO
4
2-
、HCO
3
-
and pH,was measured by experiment. All data were analyzed by SPSS and Excel for statistical analysis.
[Results]
The cations in distribution areas of
S. heteroptera
were mainly Na
+
, K
+
, Ca
2+
and Mg
2+
, while the anions were mainly Cl
-
, SO
4
2-
and HCO
3
-
. The soil salinity anions in each layer were mainly Cl
-
, accounting for 18.55%, 17.3% and 23.95% of soil base ions at 0-10 cm, 10-20 cm and 20-30 cm, respectively. Cations were mainly Na
+
, accounting for 43.2%, 42.2% and 35.8% of 3 soil layers from top to bottom. Correlation analysis results demonstrated that the soil total salt content and HCO
3
-
, was positively associated with other base ions, the anion in the strongest correlation with total salt was Cl
-
, and the correlation coefficient was 0.966; the cations in the strongest correlation were Ca
2+
and Na
+
, and the correlation coefficient was 0.956 and 0.912, respectively, The correlation between soil pH and HCO
3
-
was insignificantly positive, but negative correlation with other base ions. The pH value at the junction of reed and
S. heteroptera
area and pure
S. heteroptera
area were higher than that at the junction area of bare beach and
S. heteroptera
, and the pH value generally increased with the deepening of soil layer. The results of principal component analysis showed that the 4 ions of Na
+
, Ca
2+
, Cl
-
and SO
4
2-
accounted for more than 85% of all base ions in the soil at a depth of 0-30 cm within the region, which were the main ion types affecting soil salinity. The HCO
3
-
presented a certain effect on soil alkalinity.
[Conclusions]
The thresholds of soil salt content in 0-30 cm ranged in 9.54-18.46 cmol/kg in the pure
S. heteroptera
growing area and its 2 junction areas of Liaohe estuary wetland. The results of principal component analysis provide theoretical basis for comprehensive analysis and evaluation of soil salt spatial distribution in
S. heteroptera
community and its interlaced areas.
2019 Vol. 17 (1): 117-123 [
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124
LUO Zhidong, LIU Erjia, QI Shi, ZHAO Yuan
High-resolution remote sensing monitoring and evaluation engineering mode of soil erosion based on system engineering
[Background]
High-resolution remote sensing technology is an important means to monitor and evaluate soil erosion. The regional applicability of high-resolution remote sensing information extraction automation algorithm is poor, the multi-period dynamic error fluctuation of remote sensing information extraction results is large, the integration of remote sensing information extraction and soil erosion monitoring and evaluation business is poor, and the overall application efficiency is not high.
[Methods]
Based on the research status of soil erosion monitoring and evaluation by high-resolution remote sensing, this paper considered the application of remote sensing technology in soil erosion monitoring and evaluation as a whole by using the principles and methods of system engineering, and put forward the construction idea of engineering model of high-resolution remote sensing monitoring and evaluation of soil erosion. This paper also clarified the conceptual connotation and main characteristics of the model, and put forward the overall framework of the model, as well as the construction content and implementation approach of the key elements of the model.
[Results]
After research, the model mainly includes 3 core elements:engineering comprehensive knowledge base model, engineering remote sensing information extraction algorithm model and engineering integrated model. Among them, the engineering comprehensive knowledge base model is mainly based on the spatial management framework system of parallel integration of soil and water conservation zoning and county administrative divisions, which standardizes and solidifies business and expert knowledge; the engineering remote sensing information extraction algorithm model is mainly to extract target objects and sub-regions for different high-resolution remote sensing information. An information extraction algorithm set with model and algorithm as the core is established, and the engineering integrated model mainly integrates the basic data, application software system and infrastructure equipment environment. In Hengshan county of Yulin city, Shanxi province, a demonstrating application on agriculture and animal husbandry was carried out. Automatic overall classification accuracy was 87.58%. After the engineering model corrected, classification accuracy was 95%. Based on the engineering application of the system platform and using integrated basic data, we completed the evaluation of soil erosion in Hengshan county, andthe overall efficiency of the evaluation increased by 2-3 times.
[Conclusions]
This model realizes systematic and collaborative optimization of monitoring and evaluating soil erosion using remote sensing, greatly improves its the stability, accuracy, practicability and comparability, and may provide technical support to promote dynamic assessment and governance of Chinese soil erosion.
2019 Vol. 17 (1): 124-130 [
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131
ZHAO Yongjun, YUAN Pujin, LIU Xianchun
Considerations on the positive and negative list in the administrative examination and approval of soil and water conservation scheme
[Background]
In order to do well the reformation of the administrative examination and approval items, the Ministry of Water Resources will explore and formulate list of positive and negative sides for the approval of soil and water conservation scheme.
[Methods]
In this paper, the practical work of several kinds of positive and negative lists,such as Industry access, project access, access to government and administrative approval are summarized and analyzed. Also, some related research about soil and water conservation are consulted. On this basis, the basic principles and general ideas of the positive and negative list for the approval of soil and water conservation scheme are put forward.
[Results]
The main contents of positive and negative list from the basic case of the project, the project site, construction scheme, construction organization and scheduling, waste disposal, earthwork, debit the scope of responsibility, control objectives, control measures of soil and water conservation, the construction organization and scheduling of the soil and water conservation measures, monitoring, investment etc., are discussed. The positive list includes 13 items, such as:1) The scheme is reported before construction. 2) Site selection does not involve restricted areas. 3) The project construction plan describes clearly. 4) Main earth and stone square engineering construction technology is clear. 5) The responsibility boundary for soil erosion control is clear. 6) The standard grade and index value of soil erosion control are clear. 7) The location of abandoned soil(slag) field is clear and meets for compliance of site selection. 8) The system of measures for water and soil conservation in sub-districts is complete and the design standards are clear. 9) Topsoil protection measures are clear. 10) The task, content and reporting system for soil and water conservation monitoring and supervision are clear. 11) the compensation for soil and water conservation is clear. The negative list includes 11 items, the scheme will be refused if any item can not be satisfied. Among the items, several questions should be taken more attention, such as, if the project has been constructed or finished without government's approval, persons or the organizations should be punished. The scheme can not be admitted if the construction progress did not implement the "Three simul taneity" system and did not satisfy the principle of first stopping and then abandoning.
[Conclusions]
It is a powerful action that the positive and negative list of approval of soil and water conservation scheme are carried out. This will reduce the discretionary power of the executive branch, and support the public's right to know. In general, the soil and water conservation scheme that is meet the requirements of the positive list, the administrative examination and approval procedures will be simplified or accelerated. If the scheme that is meet the requirements of the negative list, it will be refused.
2019 Vol. 17 (1): 131-136 [
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