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2017 Vol.15 No.2
Published 2017-04-30
1
LIU Yuzhen, Alimujiang KASIMU, Abudumijiti ABULIKEMU
Remote sensing monitoring of dynamic change of desertification in typical areas along the Silk Road Economic Zone
[
Background
] Under the influence of high intensive human activities, resources and environment of "Silk Road Economic Zone" is facing severe problems and challenges. The ecological environment is very fragile along this region, especially in the middle part of the Second Eurasian Continental Bridge. Desert and Gobi area accounts for the greater proportion in this region, and desertification problems are very serious. The development and maturity of remote sensing technology may provide strong support for the analysis of the dynamic change of desertification.[
Methods
] MOD13Q1 with 250 m resolution from 2000 to 2014 were used as data sources, and normalized difference vegetation index method was applied to estimate vegetation coverage, and decision tree classification method of vegetation coverage was to classify desertification degree, then the dynamic change and transfer matrix of land desertification in Silk Road Economic Zone were obtained. [
Results
] The desertification land in the study area increased from 2000 to 2014, in which the growth amount of desertification land was 98 912.26 km
2
and the annual growth rate was 0.11%. Among them, the total area of none desertification transferred to desertification was 308 289.73 km
2
, which was larger than that of desertification transferred to none desertification and the area was 266 497.67 km
2
. In spatial distribution, the desertification degree in Central Asia gradually reduced from extremely severe desertification in southwest to light desertification in northeast, and this desertification trend was moving towards the north part of Kazakhstan constantly. Land desertification in China was mostly concentrated in Turpan, Tarim and Qaidam Basin, but the area of desertification in the northern part of Ningxia, Shaanxi, Gansu was reducing. [
Conclusion
] On the whole, the total desertification area along the Silk Road Economic Zone is increasing, and the desertification degree trends to more severe. The desertification problem is becoming more and more serious. By monitoring and analyzing the dynamic changes of desertification along the Silk Road Economic Zone using remote sensing during 2000—2014, this study provides a theoretical basis and data support for regulation and construction of sustainable development of the oasis in Silk Road Economic Zone.
2017 Vol. 15 (2): 1-8 [
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9
GAO Wei, YE Gongfu, HUANG Zhiqun, CHEN Zhiyong, YU Zaipeng, YUE Xinjian, CHEN Mengyao
Changes of carbon input influence soil respiration in a typical natural secondary forest on southern subtropical sandy coast
[
Background
] Globally, the pool of carbon in soils is greater than the pool contained in vegetation or the atmosphere, and changes in soil carbon content can therefore greatly affect the global carbon budget. Soil respiration is an essential process of carbon cycling in terrestrial ecosystems, thus the knowledge about influence of environmental factors and carbon input on soil respiration is critical for ecosystem management. [
Methods
] Four 20 m×20 m permanent fixed plots were established in a natural secondary forest in December 2014 in southeastern coast of Fujian Province, China, and four carbon input manipulations of root exclusion, litter exclusion, double litter and control(normal carbon inputs)were carried out in each plot. Monthly soil respiration (
R
s
) under different carbon input manipulations were measured by Li-8100 from March 2015 to February 2016. In addition, the dissolved organic carbon and microbial biomass carbon were determined after
R
s
measurement. One-way analysis of variance (ANOVA) with Duncan’s multiple comparison method was used to test the differences of
R
s
, soil temperature and soil moisture between different carbon input manipulations, besides the linear and nonlinear regression models were used to describe the relationship between seasonal
R
s
, soil temperature and soil moisture. [
Results
] The results showed that no significant difference was found for soil temperature and soil moisture at 10 cm depth between different treatments (
P
＞0.05). The seasonal pattern of
R
s
was obviously, which was higher in summer and lower in winter during the study period, and the highest fluxes observed in May 2015 or June 2015 and the lowest fluxes occurred in November 2015 or December 2015. The range of annual mean
R
s
for different treatments was double litter ＞ control ＞root exclusion ＞ litter exclusion, and all
Q
10
values in different carbon input manipulations were lower than that in control. The contribution of mineral soil, litter layers and roots to total soil respiration was 41.24%, 43.29% and 15.45%, respectively.
R
s
was significantly and exponentially correlated with soil temperature and linearly and positively correlated with soil moisture at 10 cm depth (
P
<0.05). The bi-factor models integrated W
10
with T
10
explained 45%~69% of the variations for
R
s
. The soil dissolved organic carbon and microbial biomass carbon were also influenced by carbon input changes, and the mean
R
s
significantly correlated with soil dissolved organic carbon and microbial biomass carbon concentration.[
Conclusions
] Our findings suggested that carbon input manipulations induced changes in soil labile carbon, and subsequently caused significant effects on soil respiration.
2017 Vol. 15 (2): 9-17 [
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18
DING Xuekun, ZHANG Shouhong, WANG Yujie, WANG Yunqi, LI Yunpeng
On the inter-annual variability of vegetated slope stability
[
Background
] Effects of vegetation on slope stability are mainly embodied in two ways: a) the stress of weight and wind load caused by plants; b) the effects of plant roots reinforcement. The effects of plant species and growth stages on soil may change with time, which are difficult to measure and quantify due to existing technology. This paper aims to build a evaluation model that considers the plant growth and evaluates the safety factors of the slope under different layouts with different types of plants. [
Methods
] A growth model of individual-plant was used to obtain the inter-annual variation characteristics of plants. Meanwhile, height, DBH, canopy and number of root properties such as root quantity, branching patterns, and root inclinations were measured and discussed. Weight, wind load, and root reinforcement were also calculated in this paper. Finally, a modified equation was used to calculate the factors of safety of different vegetated slopes. [
Results
] Results showed that weight, wind load, and plants roots resulted in large impacts on slope stability. Slopes with
Platycladus orientalis
(L.) Franco,
Vitex negundo
var.
heterophylla
might enhance 46.8% and 54.9% compared to bare slope, reaching to the top 1.549 and 1.817 from the 30
th
year to 50
th
year respectively. After that, the safety factors of vegetated slopes tended to stabilize during the later growth. The effect of weight and wind load weakened slope stability. The influence of weight decreased safety factors about 0.1% and 0.7%, and the roots had decreased safety factors about 5.9% and 5.8%. [
Conclusions
] Based on the results, this paper concludes that the weight of plants and wind load may reduce safety factors, but root presents positive effect on slope stability. With the changes of years, effects of plant weight on slope stability mainly remain unchanged in the whole growth period. However, effects of root and wind load may increase during the early growth stage and then remain unchanged during the later stage. When evaluating vegetated slope stability, effects of plant weight, roots and wind load cannot be ignored or the safety factor may be overestimated or underestimated. In addition, the results provide reference to a reasonable layout in protecting slope and may be conducive to the ecological engineering construction.
2017 Vol. 15 (2): 18-24 [
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602
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25
ZHOU Ping, WEN Anbang, YAN Dongchun, SHI Zhonglin, LONG Yi
Understanding the effects of contour hedgerow and terracing hedgerow on soil and water conservation in the remote mountainous regions of Southwest China
[
Background
] Soil and water loss is a serious worldwide environmental problem, for example, soil loss from the sloping cultivated lands in the remote mountainous regions of Southwest China due to the abundant precipitation and steep sloping cultivated lands in these areas. Various soil protection techniques have been adopted to prevent soil loess, the local people did not admire the introduced contour hedgerow measurement from abroad; however, they have been actively accepted another traditional one, the terracing hedgerow. The purpose of this work is to understand the differences on soil and water conservation between contour hedgerow and terracing hedgerow. [
Methods
] The different structure between four treatments of contour hedgerow and terracing hedgerow were analysed. Meanwhile, three heights (0 cm, 10 cm, and 15 cm) of lynchet were set, and the soil erosion module, runoff efficiency, ratio of output and input, economic effects among the different treatments were compared. The soil anti-scourability was calculated using the equation, and analysis of variance ( ANOVA) was performed with SPSS 11.5 and Microsoft Excel software. [
Results
] The obvious difference was that terracing hedgerow with a certain height of walkway was more convenient for farming activities and effectively reduced soil and water loss. The treatment of terracing hedgerow 2 ( H15H) reduced runoff 55.56%±6.25% and reduced erosion modulus 79.26%±3.50% when compared to the sloping cultivated land plots with no lynchet and no hedgerow ( CK). The contributions of the independent variables on runoff, soil erosion reduction and soil anti-scouring were in the following order: terracing hedgerow 2 (H15H) > terracing hedgerow 1 (H10H) > contour hedgerow (H0H) > non-hedgerow (CK). The value of ratio of output to input of H15H treatment was 1.52, which was the highest value among different treatments. [
Conclusions
] Although the treatment of terracing hedgerow 2 ( H15H) needs more labour force, however, results in the higher hedgerow yield and ratio of output to input than other treatments as well as stronger anti-scourability. Thus, the traditional terracing hedgerow with 15 cm lynchet is recommended in the remote mountainous regions of Southwest China, even should be recommended often and used extensively in the similar climatic regions in other countries.
2017 Vol. 15 (2): 25-34 [
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35
LI Panpan, WANG Bing, LIU Guobin, LI Binbin
Effects of nitrogen addition on the population characteristics of
Bothriochloa ischaemum
and soil properties
[
Background
] Grassland ecosystem plays a great role in improving regional environment condition and maintaining soil and water. With the nitrogen deposition increasing, vegetation characteristics and soil properties of grassland ecosystem would be changed, which in turn influence their effects on reducing soil erosion.
Bothriochloa ischaemum
community is considered as typical vegetation on the Loess Plateau. Besides, the nitrogen content of soil in this region is relatively low. Hence, researching nitrogen addition effect on the characteristics of
B. ischaemum
community has a great significance in vegetation construction and soil and water conservation. [
Methods
]
B. ischaemum
was seeded in the soil bin (2 m in length and 1m in width; soil bulk density was 1.2 g/cm
3
) with 20 cm row spacing for each plant. Totally, 50 plants of
B. ischaemum
were seeded for each soil bin. Watered regularly during the first year and added nitrogen in the next year. Ammonium nitrate was used as nitrogen source with four nitrogen levels (0, 2.5, 5 and 10 g N/(m
2
·a)), which was added to the soil once every two weeks from June to August (six times in total). Moreover, the bare loess soil was selected as control. For each treatment, there were three repetitions and 15 soil bins totally. Inflorescence number and plant height of
B. ischaemum
were measured before each nitrogen addition, also the soil was sampled (0-5, 5-10, 10-20, and 20-30 cm) at the same time to determine the soil organic matter, total nitrogen and phosphorus, available nitrogen and phosphorus, pH and particle size distribution. At the end of growth stage, vegetation coverage, biomass of aboveground and roots (65 ℃, 48 h) were measured. In addition to this, root characteristics such as total surface area were measured with WinRHIZO software. The differences of vegetation characteristics and soil properties between all treatments were analyzed by multiple comparison method. [
Results
] 1) The height and inflorescence number of
B. ischaemum
reached the maximum at the nitrogen addition level of 2.5 g N/(m
2
·a), then decreased with the enhancement of nitrogen addition. 2) The aboveground biomass increased significantly with the growing nitrogen addition level (
P
<0.05) and the root biomass density of
B. ischaemum
got its maximum at 5 g N/(m
2
·a) nitrogen addition level. However, with nitrogen addition increased, root biomass density showed a decreasing trend. 3) With the nitrogen addition up, the soil organic matter and nitrate nitrogen content increased, while available phosphorus content decreased, whereas, there was no significant relationship between nitrogen levels and total nitrogen or ammonium nitrogen.[
Conclusions
] This study indicated that nitrogen deposition had a significant effect on grassland ecosystem. The
B. ischaemum
grew well with the certain nitrogen addition level, while lower or higher nitrogen addition level may limit its growth. This study may make a better understanding of potential impact of nitrogen deposition on the characteristics of vegetation and soil properties, and would provide fundamental scientific basis for regional vegetation construction under the background of global atmospheric nitrogen deposition.
2017 Vol. 15 (2): 35-42 [
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43
LI Xiaoqian, XIA Jiangbao, ZHAO Ximei, YANG Jihua
Water and salt distribution characteristics of shallow soil at different diving water levels
[
Background
] Water and salt distribution of shallow soil are the main affecting factors of seedling growth. Taking soil columns planted with
Tamarix chinensis
Lour.(3-year-old), a constructive species in the Yellow River Delta as the research object, we aimed at studying how the diving water level (DWL) affects the water and salt distribution. [
Methods
] The experiment was carried out as such, first, planting the
T. chinensis
Lour. to soil column in the greenhouse, configuring the salt water in which mineralization degree was 6 grams per liter with sea salt, then setting up 6 diving water levels of 0.3 m, 0.6 m, 0.9 m, 1.2 m, 1.5 m, and 1.8 m, and each level set 3 repeats. In the use of drying method and residue drying method, the relative water content (RWC), salt content and absolute concentration at soil depths of 0-10 cm and 10-20 cm in a simulated device with DWL of 0.3 m, 0.6 m, 0.9 m, 1.2 m, 1.5 m and 1.8 m were measured. [
Results
] The RWC in 10-20 cm was higher than that in 0-10 cm and decreased significantly with the DWL increased (0-20 cm), but the decreasing degree in 0-10 cm was much higher than that in 10-20 cm, the highest reduction of the RWC was at both 1.2 m and 1.5 m. The salt content (0-10 cm) increased at first and then decreased with the DWL increasing, reached peak at 1.2 m (1.38%) and increased by106.35% compared with that at 0.3 m. The salt content (10-20 cm) was complex with the DWL changing, it changed smoothly at 0.3-0.9 m and increased at 1.2 m then decreased at 1.5-1.8 m, reached maximum at 1.2 m (1.33%) and increased by 304.04% compared with 0.3 m. The absolute concentration (0-10 cm) exponentially increased with the DWL increasing and maximum at 1.2 m (17.12%).The absolute concentration (10-20 cm) increased at first and then decreased with the DWL increasing and was maximal at 1.2 m (10.10%). [
Conclusions
] The RWC was significantly negative with the DWL (
P
< 0.01) while significantly positive for the salt level (
P
< 0.05); the absolute concentration (0-10 cm) was significantly positive with the DWL (
P
< 0.01) but significantly negative with the DWL (
P
< 0.01), the absolute concentration (10-20 cm) was significantly positive with the salt level (
P
< 0.01). This study provides theoretical basis and technical reference for the prevention of soil salinization in the Yellow River Delta and the planting management of
T. chinensis
Lour.
2017 Vol. 15 (2): 43-50 [
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51
YU Genting, XIA Jihong, BI Lidong, WANG Yingjun, LIN Lihuai, CAO Weijie, YI Zihan
Vegetation distribution and its driven-forces on the floodplains of small and medium rivers in hilly area
[
Background
] Vegetation in riparian zone is an important buffer to sustain the health of a river system. It is a typical ecotone characterized as edge effect, and plays a significant role in the conservation of river system health. Therefore, it is vital to know how the vegetation in floodplain distributes and what the driven-forces of the distribution are. [
Methods
] Taking the Lingshan River, in Longyou County, Zhejiang Province, as a typical example of small and medium rivers in hilly area, the characteristics of the vegetation distribution and its driven-forces were studied. After investigating the vegetation species in the quadrat sampling, the data was calculated and analyzed using the Clustering Analysis (CA) in SPSS software, and the Redundancy Analysis (RDA) in Canoco5 software and through which the composition and cluster numbers of vegetation species, the cosine of the angle at the origin of the two vectors, the contribution rate of driven-forces were calculated. On the basis of GPS site survey and the maps downloaded from Google Earth, the elevation and shape coefficient were analyzed by Digital Elevation Model (DEM) in Surfer software. Then combined with the regression analysis, the relationship between the vegetation and driven-forces were obtained. [
Results
] In the floodplain of Lingshan River, there were 62 vegetation species (61 kinds of
Angiospermaes
and one kind of
Pteridophyta
) and the vegetation community structure was mainly divided into 9 classes. The major three driven-forces of the vegetation distribution were elevation factor (ButtElev), shape coefficient (Shapindx) and hydrological characteristics (HydrChar), and their contribution rates were 37.50%, 27.50%, 16.82%, respectively. Particularly, under the influence of ButtElev, from outer to inner edge of floodplain, the moisture capacity varied from strong to weak, the diversity varied from low to high, and the biomass varied from small to large. There was at least 60 percent of the guarantee rate making the vegetation diversity between 1.03 and 1.96 when the SDI coefficient was between 2.0 and 4.0, and the Pe/Pa was between 0.12 and 0.3. The hydrological characteristics affected the morphological plasticity of vegetation and the habitat conditions of the floodplain. The sand content in the outer zone of the floodplain decreased with the increase of the distance from the water, and the anti-scour ability and moisture capacity of the vegetation decreased from strong to weak. [
Conclusions
] The elevation factor, shape coefficient and hydrological characteristics are the key driven-forces of vegetation distribution in small and medium rivers in hilly area. When we design ecological restoration projects, the three factors should be focused on, and the suitable measures should be employed in order to control and optimize the three factors.
2017 Vol. 15 (2): 51-61 [
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608
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62
LIU Wenling, MA Yujun, WU Yinan, LI Xiaoyan, LIU Lei, WEI Junqi
Effects of plateau pika’s disturbance on soil moisture characteristics of different land surface types in Qinghai Lake watershed
[
Background
] The plateau pika (
Ochotona curzoniae
) is a keystone species for maintaining the biodiversity on the Qinghai-Tibet Plateau, and its disturbance has an important influence on the function of alpine meadow ecosystem. To date, however, few studies have examined the soil moisture characteristics of different land surface types generated by the plateau pika's disturbance. [
Methods
] The study was carried out in the Qinghai Lake watershed, northeast of Qinghai-Tibet Plateau. There are four typical land surface types generated by the plateau pika's disturbance: grassland, new mound, old mound and bare land. We investigated the characteristics of soil moisture and its corresponding influence factors (including soil clay content, soil organic matter, soil bulk density, vegetation coverage, and aboveground biomass) among four land surface types, based on the continuous measurement and sampling analysis. Firstly, we analyzed the response of soil moisture to various rainfall events, and the vertical distribution of monthly soil moisture of different land surface types. Then, the redundancy analysis (RDA) was used to get the key factors leading to these differences. [
Results
] Plateau pika's disturbance often generated various surface types, resulted in the direct and indirect effects on the soil physicochemical properties, and then changed the soil moisture characteristics of alpine meadow ecosystem. The response of soil moisture at shallow layer to various rainfall events was different. The beginning time of new mound and old mound was shorter than that of grassland and bare land, and the changing extent of soil moisture response to various rainfall events had the following trend: new mound > old mound > grassland > bare land. The vertical distribution of soil moisture varied obviously between four land surface types during the whole growing season. With the increase of soil depth, the soil moisture firstly decreased and then increased for grassland, firstly increased and then decreased for new mound, and continually decreased for old mound and bare land. Generally, the soil moisture of grassland was higher than other land surface types, and the difference of soil moisture at the depth of 0-30 cm was the most significant. The key factors resulting in the differences of soil moisture among different land surface types included soil clay content, soil organic matter, soil bulk density, vegetation coverage, and aboveground biomass. [
Conclusions
] The experimental results showed that the plateau pika's disturbance accelerated the hydrological process in the beginning, and slowed it later. These results are essential in explaining the effect of plateau pika’s disturbance on water conservation capacity of alpine meadow, and could also be beneficial to the management and protection of the ecosystem in Qinghai Lake watershed.
2017 Vol. 15 (2): 62-69 [
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70
CHEN Shichao, WANG Meng, GAO Yong, WANG Ji, LIU Zongqi, WANG Xiang, ZHANG Xiaowei
Influences of the different GGR
6
concentrations on the seed vigor and germination characteristics of
Astragalus adsurgens
[
Background
] Regulator for growth, development and reproduction of the plant, is an important means to improve adaptability and production capacity, and has a key impact on ecological construction of desert land management using plant measures. The seed germination ability affects directly the growth, reproduction and production of plants, determines the success of some plants settled in the adversity, and has a critical effect on the life history, population growth, the formation and succession of plants.
Astragalus adsurgens
is one of the main species for soil and water conservation and ecological construction in the Loess Plateau of China. Understanding the effects of plant growth regulators on seed vigor and germination characteristics of
A. adsurgens
is for improving adaptive ability to adverse environment and for increasing vegetative coverage during restoration and reconstruction of vegetation. [
Methods
] The concentrations of 0, 50, 100, 150 and 200 mg/L plant growth regulator GGR
6
solution, respectively at 20 ℃ (G
50
, G
100
, G
150
, and G
200
) and dark conditions (CK) were designed to soak
A. adsurgens
seed for 24 hours, and the influences of GGR
6
on seed vigor and germination characteristics of
A. adsurgens
were observed. Seed viability test (a constant temperature of 30 ℃) and germination test (constant temperature, relative humidity of 80%, 12 h light and 12 h darkness alternating) were conducted in the artificial climate chamber for the observation of seed vigor, germination energy, germination rate, germination index and vigor index with five replications of each treatment. Excel and SAS 9.0 statistical software were used for data processing, mapping and variance analysis. The suitable GGR
6
concentration for
A. adsurgens
seed germination was selected by membership function method. [
Results
] 1) The seed germination of
A. adsurgens
was "unimodal type", and the same tendency presented in the different treatments. The order of seed germination rate was CK > G
50
> G
100
> G
150
> G
200
in the first day, and peak value of germination rate (2 to 4 days) was CK < G
50
< G
100
< G
150
< G
200
. 2) Seed vigor, germination energy, germination rate, germination index, and vigor index of
A. adsurgens
increased with increasing concentration of GGR
6
when GGR
6
concentration was below 100 mg/L. The effects of the treatments on seed vigor, germination energy, germination rate, and vigor index were not obvious when the GGR
6
concentration was higher than that of 100 mg/L, and germination index also decreased. [
Conclusions
] 1) GGR
6
solution improved the speed and rate of seed germination of
A. adsurgens
(Germination process advanced 1 day). 2) Each value increased significantly (
P
< 0.05) when the concentration were 50-100 mg/L. 3) The order of seed vigor and germination characteristic indexes based on the average values of membership function was G
100
> G
200
> G
150
> G
50
> CK. The optimal GGR
6
concentration was 100 mg/L for seed germination of
A. adsurgens
.
2017 Vol. 15 (2): 70-78 [
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79
ZHANG Hua, WANG Xinyu, ZHANG Junda, QU Bingpeng, WANG Xiaoping, GONG Xiaoqiang, ZHANG Lu, SUN Xiangyang
Investigation and distributions of the bare lands among gardens and greenbelts in winter within the 5th Ring of Beijing
[
Background
] In the north of China, large area of bare land accompanied with leaf dropping of broad leaved plant in winter, easily resulting the dust pollution and air pollution. It is important reason for the gradually worse of haze pollution in the northern cities of China. Thus, accurately grasping the distribution of bare land in winter and establishing a reasonable management plan is of significance for environmental protection and ecological construction of northern cities of China. [
Methods
] Beijing, as one of the most representative cities in the north of China, was taken as the survey object in this study. The bare lands of gardens and greenbelts within the 5th Ring of Beijing were investigated using survey method defined in the
National Soil Survey Technical Regulation
. Total 100 survey samples were set up with board type location method. And 250 000 m
2
, accounting for 3.73% of the total area of 5th Ring of Beijing, were investigated. The study was carried out by 3 types of bare lawn, bare shrubs, and bare tree-pit land. [
Results
] Area of greenbelts was 87 539.84 m
2
, accounting for 35.02% of total area of this survey, suggesting that the majority within 5th Ring of Beijing occupied by hardening land such as buildings and roads. Among the surveyed greenbelts, the area of lawn green, shrubs green, and tree-pit green was 66 647.30 m
2
, 16 329.64 m
2
, and 4 562.91 m
2
, indicating the lawn green was the main proportion of greenbelts within the 5th Ring of Beijing. The results for bare land demonstrated that the contribution rate of bare lawn to total bare land was 78.11%, i.e., it was the major type of bare land within the 5th Ring of Beijing and corresponding measures should be firstly taken to improve bare lawn in future. Among 100 surveyed samples, 43.42% lawn green and 24.25% shrubs green became bare land in winter; moreover, the proportion of tree-pit green becoming bare land was up to 90.91%, indicating that there was no coverage for most tree-pits in winter. The regional distribution of bare land showed that 13 of top 20 surveyed plots of bare land were distributed in the area between the South 4th Ring and the South 5th Ring, accounting for 51.66% of the total surveyed bare land. This indicated that the area between South 4th Ring and the South 5th Ring exposed to severe bare land in winter. [
Conclusions
] Bare land not only caused soil erosion and soil nutrient loss with the 5th Ring of Beijing, but also increased haze pollution degree and deteriorated urban air quality. From the results that lawn green occupied a large proportion of gardens and greenbelts within the 5th Ring of Beijing, we suggest that we may strictly control the area of bare land in winter and ensure the protection of the ecological environment in Beijing in winter by planting cold-resistant turf grass varieties within the 5th Ring of Beijing to replace easy wilt turf grass, and using cut branches and bushes from maintaining gardens and greenbelts as cover materials to efficiently cover the bare land.
2017 Vol. 15 (2): 79-84 [
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455
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561
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85
WANG Hong, ZHANG Enhong, MENG Jin, XU Xiaolin
Error analysis of precipitable water vapor by GPS/MET and its application in precipitation forecast
[
Background
] The products of Precipitable Water Vapor (PWV) retrieved by GPS/MET (GPS/Meteorology) have the advantages of near real-time and for all-weather, etc., which provide more data sets for network monitoring in soil and water conservation field, thus, the data quality and the role of PWV is particularly important in precipitation forecast. [
Methods
] Comparing the PWV retrieved by GPS/MET with those observed by sounding and microwave radiometer, the data quality of GPS/MET was analyzed. The relationship of PWV retrieved by GPS/MET and ground precipitation was analyzed, and the role of PWV in precipitation forecast was investigated. The PWV data sets used in the paper which contained GPS/MET, sounding and microwave radiometer detections were observed in 2015 at Zhangqiu station located at Jinan, capital of Shandong province, an eastern city of China. The data set of rain intensity recorded by ground automatic weather stations was also used. [
Results
]1) The evolution trend of PWV retrieved by GPS/MET, sounding and microwave radiometer in 2015 was consistent, and peaks and troughs presented a well correspondence. Throughout the year, there was a clear monthly variation of PWV, showing a single peak distribution with time. Therefore, GPS/MET may reflect the variation of PWV in the atmosphere over time. 2) Although the biases between GPS/MET, microwave radiometer and sounding were large, the dispersion degree was not large, indicating that there was a systematic error between GPS/MET and the other two methods. 3) PWV started to increase about 10 hours before precipitation to the ground, and then maintained at a large value, indicating that the there was an obvious process of water vapor accumulation before rainfall. PWV reached the max value while precipitation started, the max rain intensity corresponded to max PWV well. After precipitation ended, the PWV fell rapidly. 4) The max PWV was the prerequisite of rainfall. The greater PWV value observed by GPS than average was, the larger the probability of precipitation was. For Zhangqiu station, considering the times and probability of precipitation comprehensively, the PWV increasing more than 6mm in consecutive 4 hours was selected to be an evidence of the precipitation happening. [
Conclusions
]Based on the well matching of PWV observed by GPS with the other two detections (sounding and microwave radiometer), PWV data set retrieved by GPS/MET was reliable,and played an indicative role in precipitation forecast by analyzing the relationship between PWV and rain intensity. As an interdisciplinary link between meteorology and soil and water conservation field, GPS/MET may provide data support for decision-making section and in soil and water conservation practice.
2017 Vol. 15 (2): 85-91 [
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615
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519
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92
ZHANG Le, XU Pingping, LI Suyan, SUN Xiangyang, ZHANG Tao, LIU Zihao, YAO Liyuan
Amelioration effects of organic-inorganic compound amendment on coastal saline-alkali soil
[
Background
] The urbanization level in coastal areas are higher than other areas in China, and the coastal soils in these areas are threatened by salinization, which could cause negative effects on ornamental plants surviving and growing, thus the ornamental value and ecological functions of the urban green land was reduced. In this way, the improvement of saline-alkali soil should result in a significant impact upon construction of urban green space in coastal areas. [
Methods
] The experiment was conducted in a greenbelt of Bohai district in Cangzhou City of Hebei Province, where is in high salinity. An organic modifier (Green waste compost:Pyrolysised garden wastes in 4∶1 as 0, 5%, 10%, and 15% of being-ameliorated soil volume) and phosphogypsum (0, 1, 2, and 3 kg/m
2
) were utilized for the soil amendments, totally 16 treatments by combining any 2 of them, and 0 of them as the control. Each treatment was laid in an experimental plot (12 m×6 m) with 3 repeats of planting
Sophora japonica
. Soil samples were collected at 3 random sites of topsoil (0-20 cm) in each plot in July 2014, October 2014, March 2015 and July 2015. OHAUS Starter 3C was used for measuring pH, dual-indicator neutralization titration method for CO
2-
3
and HCO
-
3
, silver nitrate titration method (Moore method) for Cl
-
, EDTA titration method for Ca
2+
and Mg
2+
, indirect EDTA complexometric titration for SO
2-
4
, flame photometry (FP6410, Shanghai) for K
+
and Na
+
, and total salt content was the sum of 8 ions’ concentrations. The data were analyzed by Excel 2010 and SPSS 18 software, single factor analysis of variance (one-way ANOVA) was to compare the differences among different treatments, and the multiple comparisons were examined by Duncan method. [
Results
] 1) The soil pH decreased obviously with the addition of organic modifier and phosphogypsum, and phosphogypsum played a leading role. To prevent the negative impacts to the plants from the drastic variations of pH caused by the application of phosphogypsum, organic modifier should be applied at the same time. 2) Single-factor experiment showed that soil SAR (Sodium Absorption Ratio) significantly decreased when this 2 soil amendments were more used. Moreover, phosphogypsum showed better effects than organic modifier. Interaction experiments showed that combined application of phosphogypsum and organic modifier achieved better effect in decreasing SAR than single application. 3) The content of Cl
-
significantly decreased with the application of phosphogypsum and organic modifier, but SO
2-
4
was the opposite. 4) The experimental results demonstrate that combined application of phosphogypsum and organic modifier was suggested to get the better effect, the recommended addition of phosphogypsum and organic modifier were 1 kg/m
2
and 5% (volume ratio, about 3.35 kg/m
2
), which improved the saline soil effectively. [
Conclusions
] Due to the low cost, waste resource recovery and the solid environmental effects in treatment process, organic modifier is more practicable in the improvement of saline-alkali soil. Besides, this improvement method for saline soil provids a feasible plan for beneficial reuse of phosphogypsum and organic modifier.
2017 Vol. 15 (2): 92-99 [
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600
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100
LI Yaoming, WANG Yujie, WANG Yunqi
Ecological risk assessment in Beijing based on GIS
[
Background
] Ecological risk assessment has been studied by many countries and research scholars. The conventional index of evaluation system is difficult to obtain, which makes ecological risk assessment in some underdeveloped regions infeasible. The constant transformation of land type and structure, the substantial reduction of agricultural land; meanwhile, industrial and mining production emissions of chemicals has caused the environmental degradation in mountainous areas, population explosion, habitat loss, loss of biodiversity, etc. China's current risk assessment borrows from other types of ecological risk assessment system, which does not have an appropriate assessment system, and data collections some evaluation indicators of are too complicated. Thevefore, how to evaluate ecological risk assessment in practice? How to conduct effective ecological risk assessment and benefit of the production and construction? [
Methods
] Based on the research of ecological risk assessment, we analyzed the system according to sources of risk, risk receptors, exposure and hazard. Taking Beijing as the data source for remote sensing images, combined with GIS tools to analyze Beijing ecological risk level of distribution, selected multiple indicators were analyzed. We also studied key indexes in Beijing ecological risk assessment system, and endowed weights for each indexes, and finally obtained Beijing ecological risk assessment maps. [
Results
] 1) In densely populated areas, there have a higher ecological risk levels (Moderate risk and High risk) because of its closely related to human activities. 2) Overall, ecological risk level (Mild risk) of northern and western mountain area is higher than those in the southern and the eastern. 3) When two regions have the same ecological risk level, the major sources of risk may be different due to regional characteristics, however, neighborhoods trend to have the same major sources of risk. 4) By building and screening the index and ecological risk assessment system, a reasonable transformation of these indicators for ecological risk assessment system has been fitted in this system. At the same time, combined with the current research progress and soil and water loss investigation, it can be used in other parts of ecological risk assessment model for other areas. [
Conclusions
] Based on an earlier ecological risk assessment theory, the new ecological risk assessment methods can overcome the shortcomings of traditional single-factor evaluation, comprehensive index evaluation, and conducive to ecological risk assessment for other regions.
2017 Vol. 15 (2): 100-106 [
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478
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2021KB] (
537
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107
XU Jiajia, YU Zhancheng, SHI Longjun, ZHANG Xiaoxia, ZHANG Jianjun
Effects of soil and water conservation measures on soil physical properties and soil anti-scourability of Beijing mountainous area: A case study of the Puwa Watershed in Fangshan District
[
Background
] In order to evaluate the effect of soil and water conservation in small watershed management in Beijing mountainous area for many years, and to provide theoretical support for small watershed management and vegetation reconstruction in the future, taking Puwa small watershed of Fangshan District in Beijing as research target, soil physical properties, soil texture, infiltration and soil anti-scourability of all major kinds of soil and water conservation measures were studied. [
Methods
] The sample plots of 7 typical soil and water conservation measures was selected and investigated, and the data were acquired through typical plot survey, test of field soil anti-scourability, and method of single-ring. [
Results
] The soil density increased and soil porosity decreased significantly with the increasing of the soil depth. The soil density, total porosity and capillary porosity varied with the measures consistently. The order of effects on improving soil structure were
Quercus liaotungensis
secondary forest >
Larix principis-rupprechtii
and
Pinus tabulaeformis
mixed forest > terraces with stone banks>
Pinus tabulaeformis
forest >
Larix principis-rupprechtii
forest >
vitex negundo
shrub, while there was no significant effect for
Platycladus orientailis
forest. The soil particles in this area were mostly rich in powder, and the fractal dimension showed that the permeability of all kinds of soil and water conservation measures was promising. Compared with weed land, the scoured soil amount decreased significantly, the runoff time was prolonged, and the order of the scoured soil amount was as
L. principis-rupprechtii
and
P. tabulaeformis
mixed forest(0.82 kg/cm
3
)<
P. orientailis
forest(1.14 kg/cm
3
)<
L. principis-rupprechtii
forest(1.30 kg/cm
3
)<
Q. liaotungensis
secondary forest(3.91 kg/cm
3
)<
P. tabulaeformis
forest(5.96 kg/cm
3
)<
vitex negundo
shrub(10.88 kg/cm
3
), and the order of runoff scouring time was as
Q. liaotungensis
secondary forest(55.65 s/m)>
L. principis-rupprechtii
and
P. tabuliformis
mixed forest(46.82 s/m)>
L. principis-rupprechtii
forest(28.19 s/m)>
vitex negundo
shrub(22.39 s/m)>
P. orientailis
forest(17.48 s/m)>
P. tabuliformis
(16.94 s/m).The amount of soil loss showed a negative correlation with fine sand, medium silt, but a positive correlation with non-capillary porosity, indicating that the effect of non-capillary pore size formed by large diameter roots on soil erosion resistance might be negative. [
Conclusions
] In summary, the soil and water conservation capacity of the mixed forest of
L. principis-rupprechtii
and
P. tabulaeformis
shows a great advantage followed by terraces with stone banks which should be the principal consideration of small watershed management.
2017 Vol. 15 (2): 107-114 [
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510
) [
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785KB] (
626
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115
Aikeremu·REHEMAN, Yusufujiang·RUSULI
Ecological effects of the First Water Diversion Hub Station in Kaidu River based on the vegetation index
[
Background
] Human activities including water conservancy projects construction and water diversion affect the regional hydrological process and ecological environment. Water conservancy construction is a double-edged sword, due to coexisting both advantages and disadvantages for environmental security and socio-economic development. The impact of water division on ecological water uses has become the focus of environmental impact assessment for water diversion projects in arid regions. Scientific analysis and precise evaluation of the water conservancy project construction provide an important theoretical basis for the harmonious development of regional water conservancy project and ecological environment. Many water conservancy projects have been built to meet the needs of economic and social development in the Yanqi basin, Xinjiang, China since several decades. The First Water Diversion Hub Station built in 1999 is a most important water conservancy project in Kaidu River, and it leads to change of land cover and alter the underlying surface conditions obviously. In this paper, the ecological effects of the First Water Diversion Hub Station in Kaidu River were carefully studied by the technologies of geographic information system and remote sensing. [
Methods
] Considering the vegetation situation of study area, the land cover was classified as bare land, sand, cultivated area, wetland and water from Landsat images. In order to eliminate the influence of the soil background on the vegetation index as far as possible, the adjusted soil-vegetation index (SAVI) was used as the vegetation index of the vegetation cover types. The biomass in different land cover types were calculated using SAVI respectively. Then, the impact of water conservancy project construction on the change of vegetation cover and biomass was discussed together with hydrological data encompassed the period between 1974 and 2014. [
Results
] After The First Water Diversion Hub Station completed,the land use dynamic degree increased (
R
t
=0.29), the growth of cultivated land and water body were especially obvious. The cultivated land increased approximately 104.9% during 1994 and 2015; at the same time, the bare land decreased about 53.8%. Based on the comparative analysis of water resources utilization efficiency and ecological environment quality before and after the water conservancy project built, the annual ineffective water loss amount decreased about 1.045×10
8
m
3
. It is understood that the water conservancy project effectively adjusted the spatio-temporal distribution of water resources in Kaidu River oasis area, and met the human requirements for water resources utilization. After the operation of water conservancy project,the vegetation coverage and biomass of the study area increased, and bare land decreased gradually. [
Conclusions
] On the one hand, the First Water Diversion Hub Station in Kaidu River improved the water diversion and allocation conditions, the original goal of efficient water resources utilization were achieved. On the other hand, it plays an important role in the ecological environment by increasing the regional vegetation coverage.
2017 Vol. 15 (2): 115-124 [
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608
) [
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4183KB] (
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125
LIU Fang, HE Baoyin, KOU Jiefeng
Landsat thermal remote sensing to investigate the present situation and variation characteristics of karst rocky desertification in Pingguo County of Guangxi, Southwest China
[
Background
] Karst rocky desertification is a serious ecological problem in the southwest of China, and the degradation of ecosystems limits the regional social and economic development, which attracts extensive attention. Remote sensing technology shows many advantages, such as rapidness and economy. It is an indispensable means for rapid, large-scale, qualitative evaluation and quantitative information extraction of rocky desertification. The traditional remote sensing monitoring method of Karst rocky desertification (KRD) is mainly based on visual interpretation and comprehensive index method. Both methods need large workload but in low efficiency. The KRD monitoring method based on thermal infrared remote sensing was proposed to explore the thermal characteristics of Karst rock. The method has the advantages of clear physical meaning concise method and less subjectivity. [
Methods
] The method is based on the limestone reflectivity different from vegetation reflectivity in the vicinity of 11 μm in the thermal infrared band, where limestone is a reflectance peak and the vegetation reflectivity low. A typical sample area of KRD was established with reference to the high resolution image of Google Earth, and the threshold temperature of typical desertification area was determined. The research covers the determination of grading index of rocky desertification, the extraction of Karst area in Pingguo County, the extraction of construction land, the determination of rocky desertification grade threshold, the classification of KRD, the distribution characteristics of KRD at various levels, and dynamic analysis of KRD. [
Results
] In 2014 each level of KRD accounted for the total Karst area in Pingguo County: none KRD was 18.47%, mainly distributed in the gentle areas; potential KRD was 32.90%, widely distributed in Pingguo karst area; slight KRD was 24.80%, was striped in the middle and southwest of Pingguo County karst area; moderate KRD accounted for 18.94%, showed a strip along the mountain trend distribution; severe KRD accounted for 4.89%, was flat or dotted distribution of Pingguo County southeast and central. Classification results of KRD in 2006: none KRD was 16.08%, potential was 33.24%, slight accounted for 22.18%; moderate KRD accounted for 20.63%; severe KRD accounted for 7.15%. The analysis of KRD change in Pingguo County shows that the overall situation of KRD in 2014 is better than that in 2006, but the KRD in some areas has a tendency of deterioration. [
Conclusions
] Compared with other methods, the method proposed in this paper reduced the artificially subjectivity of traditional visual interpretation and improved the efficiency of interpretation. Compared with KRD index, the method is more concise and needs less data. The method can obtain more objective and accurate karst rock desertification information and can be popularized and applied.
2017 Vol. 15 (2): 125-131 [
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655
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3588KB] (
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132
ZHANG Yawen, XU Wensheng, HAN Pei, SHEN Shengyu, WANG Zhigang, ZHANG Pingcang
Application of the UAV remote sensing technology in soil and water conservation monitoring in construction projects: A case study of water resources allocation for the region of north Hubei
[
Background
] The Unmanned Aerial Vehicle (UAV) remote sensing is a new technology for soil and water conservation monitoring. It fills the gap between satellite remote sensing and surface observation, which provides a flexible method for users. However, as to combine this new technology with the criterion and specification in soil and water conservation monitoring in construction projects, more practices are needed. [
Methods
] We conducted a case study for the application of UAV remote sensing technology in soil and water conservation monitoring. This case study was based on a practical construction project called "Water Resources Allocation for the Region of North Hubei" and was divided into three parts: the acquisition of basic remote sensing data, the extraction of monitoring information and the application of information in monitoring work. First, we took the aerial images of some typical regions of the project, then using the software Agisoft Photoscan Professional, we processed the raw data to generate two products, the Digital Elevation Model (DEM) and Digital Orthophoto Map (DOM) for each region. Finally, based on the criterion and specification in soil and water conservation monitoring in construction projects, the application of extracted information from the DEM and DOM results aims to apply effective information into practical monitoring work [
Results
] The result showed that horizontal resolutions for all the DOM were less than 0.05 m and those for all the DEM were less than 0.2 m. The computer automatic classification was much faster than visual interpretation for classifying the land cover type. However, the computer automatic method had some problems of misclassifying the shadow of the water soil and coverings into vegetation. Based on the UAV method, the disturbed production and living areas in construction project for the exit of Jihong Tunnel, the entrance of 16
th
section, the 1
th
and 2
th
disposal area in the 16
th
section were 16 562.2 m
2
, 5 153.8 m
2
, 4 268.6 m
2
and 19 108.5 m
2
, respectively. The volume of the 1
th
and 2
th
disposal area in the 16
th
section was 11 thousand m
3
and 172 thousand m
3
. The 1
th
and 2
th
temporary cover area of the 1
th
disposal area in the 16
th
section was 166.9 m
2
and 1 229.9 m
2
, respectively. Compared to the statistical results of the construction organization, the monitoring values based on the UAV and the traditional methods were mostly controlled in 10% of the difference, meeting the relevant requirements. However, the monitoring efficiency of the UAV WAS three to five times of that by the traditional methods. [
Conclusions
] These monitoring information are all required by the criterion and specification in soil and water conservation monitoring in construction projects. Therefore, by applying UAV remote sensing technology in soil and water conservation monitoring, we may acquire some essential information quickly and easily. Our study shows the feasibility of this method and also reveals that compared to traditional monitoring methods, the information extracted by this method are more accurate and can also save the monitoring cost and improve the monitoring efficiency.
2017 Vol. 15 (2): 132-139 [
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792
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13202KB] (
584
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140
GAO Haidong, JIA Lianlian, PANG Guowei, YUAN Shuilong
Runoff-sediment effect of “fully filled” check dam and related prevention and control measures
[
Background
] Large-scale check dams in the Loess Plateau of China play a key role in sediment reduction and regional environmental improvement in the Yellow River basin. However, changes in the effects of runoff-sediment and related prevention and control measures on check dam under full capacity conditions have been rarely studied. [
Methods
] Based on geospatial data, we employed the RULSE and GAST hydrodynamic model to calculate soil erosion modulus and flow velocity, respectively.[
Results
] Here, we analyzed check dam once they reached full capacity, with the following changes found: 1) within the check dam control area, the surface slope and gully channel gradient both decreased, flow length was shortened, and the cross-section evolved from a V-shaped gully to a U-shaped gully; 2) using RUSLE computations and Guandigou No. 4 check dam as an example, the mean soil erosion modulus within the check dam control area was 4 472 t/(km
2
·a) before the check dam was built, but this decreased by 10% to 4 019 t/(km
2
·a) after the check dam was fully filled, thus
in-situ
erosion reduction was significant and sediment retention occurred from check dam construction to full capacity; 3) runoff flow velocity fell significantly from 0.83 m/s before construction to 0.27 m/s after the check dam reached capacity, but runoff flow velocity on the outer slope of the check dam increased significantly, in particular, the maximum runoff flow velocity at the bottom reached 3.76 m/s; and 4) "off-site" erosion reduction of the check dam decreased once the check dam reached full capacity. [
Conclusions
] Based on the above changes observed under the extreme siltation conditions, the following prevention and control measures are proposed: 1) spillway-based flood discharge works should be established in the gully channels of all catchments to improve connectivity within a branch gully and between branch and main gullies, thereby increasing flood discharge capacity; 2) the planting of trees and grasses and creating terraced fields built with local conditions considered should be undertaken to enhance slope erosion control, reduce flood and sediment supply to the slope surface, dissipate water erosion energy on the slope surface, and lower the risk to dam farmland after full capacity is reached; and 3) catchwater drains and drainage ditches, as well as engineering and vegetation measures, should be implemented to help prevent and control dam and steep slope erosion and increase vegetation cover of the outer slopes of a dam body. The results of this study are intended to provide scientific evidence to help improve check dam construction in the Loess Plateau of China.
2017 Vol. 15 (2): 140-145 [
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617
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146
ZHANG Hongri, WANG Guiyao, LAN Sulian, XIA Yiqi, SHA Linchuan
Effects of mud with rice straw as slope protection material on the water migrationin highway subgrade
[
Background
] In the southern China moist region, rainwater infiltration of slope surface and water migration in subgrade are the main factors for its bearing capacity degradation. Lacking protection will lead to cracking or excessive erosion on slope surface. In order to reduce water content changing in subgrade in sunny or rainy weather, a new material consisting of clay and rice straw is developed, and its application for slope protection is probed in this paper. [
Methods
] Firstly, the mud with rice straw was prepared by mixing the shredded clay with water and rice straw in 5-10 cm. And then the permeability coefficient and anti-penetrability performance of compacted clay, pure mud, mud with rice straw and vegetation was determined by variable head permeability test and impermeability test. Afterwards, an indoor-test simulating embankment slope in continuous natural radiation and continuous slope scouring was executed to probe soil moisture inside subgrade in condition 1: bare slope, condition 2: slope under the protection of pure mud, condition 3: slope under the protection of mud with rice straw, condition 4: condition 2 + grass seeds, and condition 5: condition 3 + grass seeds. Through the sampling test of the water content distribution in subgrade center of 60 cm horizontal depth under above conditions, the water migration characteristics of the subgrade under extreme weather conditions were studied. [
Result
] The permeability coefficient of the material of mud with rice straw was 0.81×10
-5
cm/s. The permeation time of mud with rice straw and vegetation samples was 21 h in the 4th and 5th dry-wet cycle penetration tests. In the dry weather condition, the moisture content of the mud decreased to 13.6% after 50 days in condition 3, and the moisture content was 17.2%-21.4% after 50 days in condition 5 in which the water content of the soil was stable. In the heavy rainfall scouring test, the water content of the condition 3 and condition 4 was only slightly increased at the 6th hour, while the water content of the soil in the horizontal depth of 20 cm was slightly increased in condition 5. [
Conclusions
] Mud with rice straw presents small permeability coefficient and optimal permeability. The mud cracks was reduced in dry weather and soil moisture was effectively maintained, what was beneficial to the plant growth. The mud with rice straw can improve the moisture migration performance in slope surface under heavy rainfall erosion, and keep the stability of the internal moisture content in subgrade. After the vegetation root growth and development, it can form a green ecological environmental protection system, thus, it has a great significance to highway ecological construction.
2017 Vol. 15 (2): 146-152 [
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606
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4058KB] (
536
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