Wuqi County Research Articles

The evaluation of soil stability in loess hilly and gully region of Northern Shaanxi based on GIS

Based on the previous research in loess hilly region of Northern Shaanxi, this paper takes the soil erosion degree as the main measure of soil stability and the soil utility, annual average rainfall in flood season (from June to September), and topography, as the main measure indexes of soil stability. After that, the evaluation system of soil stability in loess hilly region of Northern Shaanxi can be constructed, which can be done by special analysis of GIS. The results illustrate that the soil stability showed a trend of high south‐east and low north‐west. Soil with good stability is mainly distributed in Ganquan County, and Yanchuan County, where vegetation coverage is high, vegetation types are mostly forest land and grassland, ecological environment is good, and precipitation erosion effect is not significant. Soil with intermediate stability is mainly distributed in Baota district and its surrounding areas, where the main vegetation types are bush fallow and grassland, and the terrain is flat and gently rolling. Soil with the worst stability is mainly distributed in Suide County, and Wuqi County. The area is mostly sandy and desert, the terrain is fragmented, soil is loose, vegetation cover is not high, making the soil the worst soil stability, and strong rainfall conditions are prone to soil erosion. The prerequisite of the implementation of soil consolidation projects is having evaluation on soil stability. The research results can be the theoretical evidence, and implement guarantee of regional soil exploitation and reorganization, and the reference to enhancing the assurance of ecological safety.

Niche of main populations and environmental interpretation in grassland of Loess Plateau hilly region, China

Focused on different rehabilitation ages grassland in Wuqi County in loess hilly region, the present study aimed to explore niche characteristics of populations and their influence factors. The results showed that the dominant species were Artemisia sacrorum, A. leucophylla, A. scoparia, Lespedeza daurica and Poa sphondylodes, and the dominant species varied along with the rehabilitation age. The niche breadth of dominant populations increased with increasing rehabilitation age from 5 to 10 years, indicating enhanced adaptability to the environment. The niche breadth indices of the populations decreased from 10 to 20 years, and then increased from 20 to 25 years. After 25 years, the niche breadth of the grassland narrowed gradually, indicating weakened adaptability. The niche breadth indices of most populations peaked at 10 and 25 years, respectively. There was no li-near relationship between synthetic dominance index and niche breadth in different grass communities. With the increasing rehabilitation age, the niche overlap indices were highest at 15 years with a single hump pattern, indicating that the interspecific competition increased to the highest at 15 years and then decreased. It was shown that attitude, soil water content (SWC) and soil organic matter content (SOM) were the main factors affecting the niche breadth, while soil total nitrogen content (STN), attitude and SWC were the main factors affecting the niche overlap. There was no linear relationship between niche breadth and niche overlap of tested species in different rehabilitation ages due to resource spatial heterogeneity and growth stages of grass species. These findings indicated that with the increasing rehabilitation age, the population adaptability to the environment are generally enhanced and the resource competition among populations increases and then decreases. It was concluded that attitude, SWC and STN were the key environmental factors that affect population adaptability and interspecific relationship in natural grassland of loess hilly region.

Competitive Edge of Riverbank Villages and Problems of Hilly Villages in the Rural Loess Plateau of China: Using a Statistical Table of Wucangbao Township, Wuqi County, Shaanxi Province

Competitive Edge of Riverbank Villages and Problems of Hilly Villages in the Rural Loess Plateau of China: Using a Statistical Table of Wucangbao Township, Wuqi County, Shaanxi Province

The Dynamic Trend of Soil Water Content in Artificial Forests on the Loess Plateau, China

Extensive vegetation restoration projects have been widely implemented on the Loess Plateau, China, since 1998. In addition, increasing attention has been paid to the influence of revegetation on soil water. However, the response of the soil water content (SWC) to vegetation construction and management has not been adequately studied. In this study, three types of typical artificial vegetation on level bench land were selected, including Pinus tabulaeformis Carr., Prunus sibirica L., and Hippophae rhamnoides Linn., with the natural grassland used as a control group in Wuqi County. The 0–160 cm SWC was monitored biweekly from August 2010 to June 2013 using a portable time domain reflectometry system. The serial autocorrelation test, Mann–Kendall trend test, and prewhitening Mann–Kendall test were employed to systematically analyze the trends in soil water dynamics. The results show that the SWC of the three selected artificial forests/shrub had a significant accumulation process in the 0–160 cm profile during the monitoring period, whereas such an increasing tendency was not observed for natural grassland. Furthermore, the greatest responses were observed in the Pinus tabulaeformis Carr. plantation.

Changed surface roughness by wind erosion accelerates water erosion

Wind and water erosion are two dominant types of erosion that lead to losses of soil and water; understanding their interactions is important for estimating soil quality and environmental impacts in regions where both types of erosion occur. This study was devoted to investigate the characteristics of the surface roughness, runoff, and erosion rates under a one-way wind erosion-rain erosion sequence. The experimental setup included a wind tunnel and a rain simulator. Soil samples were collected from a sloped wasteland in Wuqi County, northern Shaanxi province, China. This experiment was conducted with wind erosion firstly and water erosion thereafter, with three wind speeds (0 [control], 11, and 14 m s−1) and rain intensities (60, 80, and 100 mm h−1). The physical properties of top soil samples (0–1 cm) were analyzed after each wind erosion test. The soil surface roughness (mm), runoff (mm h−1), and erosion (g m−2 h−1) rates were calculated after wind and water erosion. Linear regression analysis was used to estimate the relationships between surface roughness, runoff rate, erosion rate, and erosion factors. Wind erosion increased the sand content in the top 1 cm of soil in simulation area by 6.51–6.74 % and decreased clay and silt contents by 7.65–9.15 and 17.94–18.15 %, respectively, relative to the original surface soil. Compared with the control, the wind erosion treatments increased the surface roughness, runoff, and erosion rates by 8.12–78.06, 4.5–21.69, and 7.25–38.97 %, respectively, at wind speeds of 11 and 14 m s−1. The relationship between runoff and rain duration under different rain intensities after wind erosion were described well by a logarithmic function, whereas a large degree of variation was observed in erosion rate. The increased values of runoff and erosion rates in the different treatments, however, became weaker with increasing rain intensity, probably due to the much higher energy of the rain at the highest intensity, which decreased the proportional influence of wind erosion on the microtopography of the soil. Linear regression showed that surface roughness, runoff, and erosion rates were positively associated with wind speed and rain intensity (P < 0.01). Wind erosion clearly has the capacity to intensify water erosion. Results demonstrate the need for controlling of wind erosion to reduce water erosion in regions where both types of erosion occur. Moreover, a consideration of the impact of wind erosion on water erosion is required for effective erosion prediction in these regions.

Effects of microtopography on spatial point pattern of forest stands on the semi-arid Loess Plateau, China

Microtopography may affect the distribution of forests through its effect on rain redistribution and soil water distribution on the semi-arid Loess Plateau, China. In this study, we investigated the characteristics of microtopography on two shady slopes (slope A, 5 hm2, uniform slope; slope B, 5 hm2, microtopography slope) and surveyed the height, the diameter at breast height and the location (x, y coordinates) of all selected individual trees (Robinia pseudoacacia Linn., Pyrus betulifolia Bunge, Populus hopeiensis Hu & Chow, Armeniaca sibirica Lam., Populus simonii Carr. and Ulmus pumila Linn.) on slope A and slope B in the watersheds of Wuqi county, Shaanxi province. Subsequently, the effects of microtopography on the spatial pattern of forest stands were analyzed using Ripley’s K(r) function. The results showed that: (1) The maximal aggregation radiuses of the tree species on the uniform slope (slope A) were larger than 40 m, whereas those of the tree species on the microtopography slope (slope B) were smaller than 30 m. (2) On slope B, the spatial association of R. pseudoacacia with P. betulifolia, A. sibirica, P. simonii and U. pumila varied from being strongly negative to positive at microtopography scales. The spatial association of Populus hopeiensis Hu & Chow with U. pumila also varied from being strongly negative to positive at microtopography scales. However, there was no spatial association between P. betulifolia and P. hopeiensis, P. betulifolia and A. sibirica, P. betulifolia and P. simonii, P. betulifolia and U. pumila, P. hopeiensis and A. sibirica, P. hopeiensis and P. simonii, A. sibirica and P. simonii, A. sibirica and U. pumila, and P. simonii and U. pumila. On slope A, the spatial association between tree species were strongly negative. The results suggest that microtopography may shape tree distribution patterns on the semi-arid Loess Plateau.

Impact of the Sloping Land Conversion Program on rural household income: An integrated estimation

The objective of this study is to identify the pathways of the potential impacts of the Sloping Land Conversion Program (SLCP) on household income and quantify these impacts along the identified pathways. We fulfill this objective by developing an integrated analytic framework and using data collected from Wuqi county of Shaanxi for the period 2004–2010. This integrated analytic framework enables us to formulate a structural equation model for testing hypotheses regarding the direct and indirect impacts of the SLCP. It is found that the direct effect of the SLCP on household income is positive but very small and insignificant, suggesting that retiring cropland has, at least, not reduced income from farming. Moreover, the SLCP has had a much higher and even increasing indirect impact on household income through promoting labor transfer and relaxing liquidity constraints. Overall, the SLCP's total impact on household income ranged from 3% in 2004 to 9% in 2010 excluding the insignificant direct impact. The research and policy implications of our work are discussed.

退耕还林地结构与生态功能耦合关系研究

PDF HTML阅读 XML下载 导出引用 引用提醒 退耕还林地结构与生态功能的耦合关系 DOI: 10.5846/stxb201301010007 作者: 作者单位: 北京林业大学 水土保持学院 荒漠化防治重点实验室,北京林业大学 水土保持学院 荒漠化防治重点实验室,北京林业大学 水土保持学院 荒漠化防治重点实验室,北京林业大学 水土保持学院 荒漠化防治重点实验室,北京林业大学 水土保持学院 荒漠化防治重点实验室 作者简介: 通讯作者: 中图分类号: S727. 21 基金项目: 国家"十一五"科技支撑项目（2006BAD26B0702） Modeling the degree of coupling and interaction between forest structure and ecological function in a grain for green project, Shanxi, China Author: Affiliation: key Laboratary of Soil and Water Conservation Combating of Ministry of Education, College of Soil and Water Conservation, College of Forestry, Beijing Forestry University,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:退耕还林的林地结构与生态功能效益是退耕还林工程的关键性问题。基于典型黄土高原丘陵沟壑地7种代表性的退耕还林模式的野外调查和取样分析结果，选取14个林地结构因子和2个代表性生态功能因子，对林地结构进行因子分析，并构建了林地结构与生态功能的灰色关联度模型和耦合协调度模型。用建立的模型分析吴起县退耕还林地7种模式的林地结构、土壤侵蚀及地表径流数据，结果表明，不同林地结构因子间相关度不同，经过主成分分析降维为4个主成分因子，分别反映了林分的乔木层结构指标、上层结构生物量指标、土壤层指标及其它指标；不同林地结构因子与生态功能的关联度系数不同，林地结构因子对地表径流的影响明显高于对土壤侵蚀率的影响，其中林分组成对径流的影响最明显，土壤因子影响最不明显；草本层生物量、枯落物生物量等近地表的相关结构对土壤侵蚀的作用明显。不同退耕还林模式的林地结构与生态功能的耦合协调度状况都不良好，仍需要进行调整和改善。 Abstract:Forest structure and ecological function serve important roles in China's Grain for Green project. This paper analyzes seven grain for green patterns in the Loess Plateau Gully and Hill Region using data analysis and modeling. Fourteen forest structure factors and two ecological function factors were selected for analysis; these factors were reduced dimensionally using factor analysis, and models of the degree of coupling and interaction between forest structure and ecological function were constructed. Based on the model, analysis of data related to forest structure, soil erosion and runoff was completed for the Grain for Green project in WuQi County, Shanxi Province, China. The results reveal various relationships exist between the different forest structural factors analyzed here. All the factors can be reduced dimensionally into four main factors identified here as F1, F2, F3, and F4. These four factors represent the tree layer, upper canopy layer mass, soils and an alternative factor, respectively. A component score coefficient matrix in the Grain for Green patterns was obtained by multiplying the factor coefficient and the corresponding basic data, and then combining the scores to calculate a component score. Each forest structural feature was expressed using the component score coefficient matrix, which shows that two types of forests, pure Robinia pseudoacacia and mixed Robinia pseudoacacia/Fructus Hippophae had the highest F1 score; pure Caragana intermedia forest had the highest F2 score; and pure Fructus Hippophae forest had the highest F3 score. The coupling degree of the Grain for Green patterns differed between different models, and the integrative indices of forest structure did not correlate well with those of ecological function. The integrated index measuring the relationship between ecological function and surface runoff is larger than the index measuring the relationship between ecological function and soil erosion. Forest component factors have the most obvious effect on ecological function, and the effect of the soil factor is the least obvious. The mass of herb layer, litter layer and some other structures near the ground play the main role in the ecological function of controlling soil erosion. The relationships of forest structure and ecological function in the grain for green project differ in the various patterns. Forest structure and ecological function were most closely related in areas with pure Fructus Hippophae, while index score belongs to the middle coupling coordinative level. Pinus tabulaeformis had the least interaction between forest structure and ecological function. Calculating the score for all types of models discussed above shows a measure of the degree of interaction between the forest structure and ecological functions can be measured with a score of 0.6, which is considered to indicate a weak interaction. Therefore, forest structure and ecological function should be improved during the application of any Grain for Green project in the Loess Plateau Gully and Hill Region. 参考文献 相似文献 引证文献

陕西省栎黄枯叶蛾蛹的空间分布

Trabala vishnou gigantina Yang(Lepidoptera: Lasiocampidae) is one of the most important defoliators in China.Larvae of T.vishnou gigantina feed on tender leaves primarily causing damage to the crown layer.In the last few years,the use of single species plantations combined with poor management and a lack of adequate monitoring and early warning has allowed populations of this pest to erupt and cause serious damage in Hippophae rhamnoides L.forest stands in Wuqi County,Shaanxi Province,China. Spatial distribution is one of the most important properties of insect populations.It provides dynamic information about insect populations,describes individual associations,and allows the prediction of variations in spatial distribution patterns.Geostatistical methods provide very powerful tools for explaining the spatial distribution of many species.These methods allow both the direct measurement of spatial distribution of organisms and tracking of changes in distribution over time because the exact location of the species has been documented at a specific point in time. To further investigate spatial distribution and effectively control this pest species,spatial distribution patterns of T.vishnou gigantina pupae were analyzed using geostatistical methods in pure H.rhamnoides forests with different slopes and densities.Results show high levels of pupating occurred mainly in mid-August.Also,males pupated 3.7 days earlier than females.Pupae were also widely distributed on southeastern facing shady slopes,and on west and north facing sunny slopes.Pupae gathered mainly at heights of 30—75 cm on trees.Analysis of isotropic variograms indicated T.vishnou gigantina pupae spaced themselves 95.609,47.379,79.238,and 42.415 m apart in densely forested shady slopes,open forests on shady slopes,densely forested sunny slopes,and open forests on sunny slopes,respectively,while the intensity of local spatial continuity was 0.760,0.561,0.649,and 0.407,respectively,in the above stands.Also,semivariogram analysis revealed the Gaussian model had the best fit to T.vishnou gigantina pupae distributional patterns in dense forests,implying an intense spatial aggregation pattern,while the linear model fitted best with the open forest,implying a random distribution.As the maps with Kriging interpolation described,T.vishnou gigantina pupae exhibited an edge effect and an obvious directional distribution;the pupae had a clustered distribution at the edge of the plantation and occurred in point locations scattered inside the plantation.Numbers of clustered plaque gradually declined toward the center of the forested area.This was reflected in the tendency of the pupae to cluster together on a spatial scale,and in the direction of their proliferation. Currently,T.vishnou gigantina infestations are most commonly controlled using chemical pesticides.However,H.rhamnoides is an economically and ecologically important plant,so residues need to be considered when spraying pesticides.Based on the spatial distribution characters,we suggest picking the pupa manually on the sunny slopes and especially on the edges of seabuckthorn plantations at a height of 30—75 cm to limit reproduction of this pest species.Research results demonstrate the spatial distribution patterns of T.vishnou gigantina pupae in pure H.rhamnoides forests,providing a theoretical basis and practical guidance for controlling populations of this insect pest.This research will provide a meaningful foundation for integrated pest management.

Evaluating China’s Slope Land Conversion Program as sustainable management in Tianquan and Wuqi Counties

Increased soil erosion on sloped land has become a significant environmental concern in China that has been attributed to human activities such as deforestation, over-cultivation, and over-grazing of livestock. In order to reduce soil erosion on sloped lands, the Chinese government has responded by implementing large-scale, ecological rehabilitation programs, including the “Grain for Green” reforestation project. This program involves financial incentives to transition farmers into other economic activities with the goal of reducing ecological pressures and degradation. Because of the scope and potential impacts from these programs, detailed research is needed to understand their social and ecological effects. This paper reports on research conducted in Tianquan County, Sichuan Province, and Wuqi County, Shaanxi Province, that evaluates the effects of the program upon local economies and household livelihood systems. The paper argues that the successful conversion of farmland under “Grain for Green” depends upon local government involvement, local economic development, and funding for local projects. Without economic development within rural economies, we conclude that farmers will remain dependent upon continued subsidy assistance to meet the policy’s ambitious environmental restrictions, thereby undermining the program’s long-term sustainability.

Palaeomagnetic Chronology and Paleoenvironmental Records of the Wuqi Paleolake of Late Neogene in the Northern Chinese Loess Plateau

AbstractThe sequence of aeolian red clay and loess deposited in northern China since late Neogene is an ideal palaeoclimate recorder. A profile consisting of loess, lacustrine deposits and red clay was found at Wuqi County in the northern Chinese Loess Plateau. Preliminary investigations were carried out on the typical Tufosi section in order to provide the age constraints of the lacustrine deposits (namely the Wuqi paleolake). Rock magnetic results demonstrate that the magnetic carriers of the characteristic remanent magnetization of lacustrine deposits are mainly magnetite and hematite. The correlation between the magnetic polarity sequence of the Tufosi section and geomagnetic polarity time scale is very well. The age of the bottom of the section is 4.28 Ma B. P. approximately. The Wuqi paleolake formed at about 3.0 Ma B. P. and died out around 1.2 Ma B. P. The regional environment became colder and drier during this period as implied by the variations of lithology, magnetic susceptibility, grain size and sedimentation rates. The evolution history of the Wuqi paleolake can be divided into three stages: the paleolake was formed during the period of 3.0~2.5 Ma B. P. and the water body was relatively deep; the lake became shallow markedly as the result of paleoclimate change during 2.50~2.05 Ma B. P.; during 2.05~1.20 Ma B. P., reduction of the water body led to the extinction of the lake. Climatic deterioration in this region around 1.2 Ma B. P. was the main reason for the end of the Wuqi paleolake. Besides, the headward erosion of the North Luo River caused by regional tectonism was probably a factor, too.

Agricultural Productivity Changes Induced by the Sloping Land Conversion Program: An Analysis of Wuqi County in the Loess Plateau Region

This paper examines the agricultural productivity change induced by the Sloping Land Conversion Program (SLCP) using the Malmquist index method and household data collected from Wuqi. We find that during the period of 1998-2004, the total factor productivity (TFP) grew by 15.8%. While numerous households suffered a TFP decline, the majority of them experienced a large gain. By decomposing the TFP, we further show that its increase is due exclusively to the improvement of technical efficiency rather than to technological change. To validate these findings and put them in perspective, we also estimated the TFP change with county-level aggregate data. It is revealed that driven by technological change and scale efficiency, the TFP grew slightly during the period of 1992-1998. Because of the tremendous cropland reduction and production mode shift caused by implementing the SLCP, the TFP declined substantially during the first three years of the program; due to continued improvement of technical efficiency; however, its growth accelerated later. Altogether, our evidence consistently suggests that implementing the SLCP has contributed to the agricultural TFP growth in the longer term and that the efficiency improvement has resulted mainly from the increased public expenditures for extension services and diffusion of technical knowledge. Wuqi's experience proves that it is possible to achieve environmental conservation and increase productivity simultaneously, even when facing a cropland reduction and production mode alternation.

Effects of Roads on Small Mammals

Based on the vegetation survey on 18 sampling plots in Wuqi County of Shaanxi Province, and by using the methods of substituting space series for time series and of contrastive analysis, the dynamics of plant community species diversity in the process of ecological rehabilitation in the County was analyzed from the aspects of succession time, rehabilitation mode, and slope direction. The results showed that in the 25 years natural succession series, the natural restoration community on previous cropland experienced the sequence of Salsola collina, Artemisia scoparia, Lespedeza davurica, Artemisia sacrorum, and Bothriochloa ischcemum, with the dominant species tended to be changed from annual to perennial and from low-class to high-class. The variations of species number, Margalef index, Simpson index, Shannon-Wiener index, and Pielou index in the succession process could all be described by a quadratic function y = at2 + bt + c, suggesting that after the outside pressure removed, the degraded ecosystem in loess area could naturally restore to an advanced and steady state, but the restoration rate would be very slow. With the same site factors and restoration periods, the Margalef index, Shannon-Wiener index and Pielou index of herb layer decreased in the order of naturally restoring on previous cropland (I) > converting cropland to grassland (II) > converting cropland to forestland (III) > afforestation on barren hills (IV), while Simpson index changed in adverse. Comparing with natural restoration, the community types of herb layer in II and III were at the more advanced stage of natural succession series though the species diversity index was lower, indicating that artificial planting would accelerate the succession process. In the same period of rehabilitation, the Margalef index, Shannon-Wiener index and Pielou index of natural restoration community were obviously higher on shady slope than on sunny slope, and the community type was at the more advanced stage of natural succession series, suggesting that the basic ecological rehabilitation condition on sunny slope was worse, and the succession rate was slower.