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| 1 | Assessing the effects of vegetation and precipitation on soil erosion in the Three-River Headwaters Region of the Qinghai-Tibet Plateau,China显示文摘Soil erosion in the Three-River Headwaters Region(TRHR)of the Qinghai-Tibet Plateau in China has a significant impact on local economic development and ecological environment.Vegetation and precipitation are considered to be the main factors for the variation in soil erosion.However,it is a big challenge to analyze the impacts of precipitation and vegetation respectively as well as their combined effects on soil erosion from the pixel scale.To assess the influences of vegetation and precipitation on the variation of soil erosion from 2005 to 2015,we employed the Revised Universal Soil Loss Equation(RUSLE)model to evaluate soil erosion in the TRHR,and then developed a method using the Logarithmic Mean Divisia Index model(LMDI)which can exponentially decompose the influencing factors,to calculate the contribution values of the vegetation cover factor(C factor)and the rainfall erosivity factor(R factor)to the variation of soil erosion from the pixel scale.In general,soil erosion in the TRHR was alleviated from 2005 to 2015,of which about 54.95%of the area where soil erosion decreased was caused by the combined effects of the C factor and the R factor,and 41.31%was caused by the change in the R factor.There were relatively few areas with increased soil erosion modulus,of which 64.10%of the area where soil erosion increased was caused by the change in the C factor,and 23.88%was caused by the combined effects of the C factor and the R factor.Therefore,the combined effects of the C factor and the R factor were regarded as the main driving force for the decrease of soil erosion,while the C factor was the dominant factor for the increase of soil erosion.The area with decreased soil erosion caused by the C factor(12.10×10^3 km^2)was larger than the area with increased soil erosion caused by the C factor(8.30×10^3 km^2),which indicated that vegetation had a positive effect on soil erosion.This study generally put forward a new method for quantitative assessment of the impacts of the influencing factors on soil erosion,and also provided a scientific basis for the regional control of soil erosion. | HE Qian DAI Xiao'ai CHEN Shiqi | 2020 | Journal of Arid Land2020，12，5： | 9 |
| 2 | Estimation of spatial and temporal changes in net primary production based on Carnegie Ames Stanford Approach(CASA) model in semi-arid rangelands of Semirom County, Iran显示文摘Net primary production(NPP) is an indicator of rangeland ecosystem function. This research assessed the potential of the Carnegie Ames Stanford Approach(CASA) model for estimating NPP and its spatial and temporal changes in semi-arid rangelands of Semirom County, Iran. Using CASA model, we estimated the NPP values based on monthly climate data and the normalized difference vegetation index(NDVI) obtained from the MODIS sensor. Regression analysis was then applied to compare the estimated production data with observed production data. The spatial and temporal changes in NPP and light utilization efficiency(LUE) were investigated in different rangeland vegetation types. The standardized precipitation index(SPI) was also calculated at different time scales and the correlation of SPI with NPP changes was determined. The results indicated that the estimated NPP values varied from 0.00 to 74.48 g C/(m^2·a). The observed and estimated NPP values had different correlations, depending on rangeland conditions and vegetation types. The highest and lowest correlations were respectively observed in Astragalus spp.-Agropyron spp. rangeland(R^2=0.75) with good condition and Gundelia spp.-Cousinia spp. rangeland(R^2=0.36) with poor and very poor conditions. The maximum and minimum LUE values were found in Astragalus spp.-Agropyron spp. rangeland(0.117 g C/MJ) with good condition and annual grassesannual forbs rangeland(0.010 g C/MJ), respectively. According to the correlations between SPI and NPP changes, the effects of drought periods on NPP depended on vegetation types and rangeland conditions. Annual plants had the highest drought sensitivity while shrubs exhibited the lowest drought sensitivity. The positive effects of wet periods on NPP were less evident in degraded areas where the destructive effects of drought were more prominent. Therefore, determining vegetation types and rangeland conditions is essential in NPP estimation. The findings of this study confirmed the potential of the CASA for estimating rangeland production. Therefore, the model output maps can be used to evaluate, monitor and optimize rangeland management in semi-arid rangelands of Iran where MODIS NPP products are not available. | Fatemeh HADIAN Reza JAFARI Hossein BASHARI Mostafa TARTESH Kenneth DCLARKE | 2019 | Journal of Arid Land2019，11，4： | 7 |
| 3 | 结构方程模型在兴安落叶松林生长中的应用显示文摘【目的】通过结构方程模型,确定气候、土壤和海拔对兴安落叶松林生长指标的影响以及路径关系。【方法】选取年平均气温、年平均降水量、太阳辐射、土壤全氮含量、土壤有机碳密度和海拔作为影响因素,探究兴安落叶松地上生物量、地下生物量、树高与这些影响因素的关系,并利用AMOS 21.0软件构建衡量兴安落叶松生长的3个指标与气候、土壤和海拔的结构方程模型。【结果】兴安落叶松的地上生物量、地下生物量随着海拔、年平均降水量的增大呈现先增大后减少的趋势,树高随着海拔的增加而增加。地上和地下生物量随着土壤有机碳密度的增加而增加。海拔对兴安落叶松生长的总效应系数为0.200且是正向效应,海拔对兴安落叶松生长的直接效应(0.224)大于间接效应(-0.024);气候因子对兴安落叶松林生长的总影响系数为-0.771且是负向效应;土壤因子对兴安落叶松生长的总影响系数为-0.216,其对兴安落叶松林生长起到一定的抑制作用。【结论】根据结构方程模型的路径系数,气候因子的总影响系数绝对值最大,其次是土壤和海拔,兴安落叶松林静态生长主要受到气候因子的制约。 | 高羽 李静 刘洋 乌雅瀚 巩家星 辛启睿 | 2023 | 南京林业大学学报(自然科学版)2023，47，1： | 2 |
| 4 | Regional difference and dynamic mechanism of locality of the Chinese farming-pastoral ecotone based on geotagged photos from Panoramio显示文摘Cross-regional locality research reflects the influences of natural environment and the human activities due to the abundant land types and the multiple landscape combinations in related regions. The Chinese farming-pastoral ecotone is a typical large-scale region but few studies were conducted. This research contributed to the understanding of cross-regional locality of the Chinese farming-pastoral ecotone from different scales, including national, sectional, and provincial administrative units by utilizing geotagged photos(GTPs) obtained from the Panoramio website. The major results were as follows:(1) the locality elements of the Chinese farming-pastoral ecotone included 52 free nodes classified into 8 types of scene attributes;(2) there were huge differences between locality elements of different regions, and there was a negative correlation between the similarity degree of elements of different provinces and their spatial distances;(3) the Chinese farming-pastoral ecotone could be divided into the northern, central and southern sections, whose localities had differences in element constitution, association structure and the strength of elements, system stability and the anti-interference capability; and(4) the evolution of the localities of the northern and central sections was mainly influenced by human activities, while the locality of southern section retained more natural features. On a theoretical level, this research aimed to establish the research methodology of locality from the perspective of open data on the web with strong operability and replicability. On a practical level, this research could enrich the structuring recognition of the locality of the Chinese farming-pastoral ecotone and the comprehension of its dynamic mechanism. The results provide a reference for locality differentiation protection and the development of a cross-regional scale. | WANG Fang LI Yixi DONG Ying ZHU Xiaohua | 2018 | Journal of Arid Land2018，10，2： | 1 |
| 5 | Comparison of leaf area index inversion for grassland vegetation through remotely sensed spectra by unmanned aerial vehicle and field-based spectroradiometer显示文摘Aims Remote sensing technology has been proved useful in mapping grass-land vegetation properties.Spectral features of vegetation cover can be recorded by optical sensors on board of different platforms.With increas-ing popularity of applying unmanned aerial vehicle(UAV)to mapping plant cover,the study aims to investigate the possible applications and potential issues related to mapping leaf area index(LAI)through integra-tion of remote sensing imagery collected by multiple sensors.Methods This paper applied the collected spectral data through field-based(FLD)and UAV-borne spectroradiometer to map LAI in a Sino-German experiment pasture located in the Xilingol grassland,Inner Mongolia,China.Spectroradiometers on FLD and UAV platforms were taken to measure spectral reflectance related to the targeted vegetation proper-ties.Based on eight vegetation indices(VIs)computed from the col-lected hyperspectral data,regression models were used to inverse LAI.The spectral responses between FLD and UAV platforms were com-pared,and the regression models relating LAI with VIs from FLD and UAV were established.The modeled LAIs by UAV and FLD platforms were analyzed in order to evaluate the feasibility of potential integra-tion of spectra data for mapping vegetation from the two platforms.Important Findings Results indicated that the spectral reflectance between FLD and UAV showed critical gaps in the green and near-infrared regions of the spec-trum over densely vegetated areas,while the gaps were small over sparsely vegetated areas.The VI values from FLD spectra were greater than their UAV-based counterparts.Out of all the VIs,broadband gen-eralized soil-adjusted vegetation index(GESAVI)and narrow-band nNDVI2 were found to achieve the best results in terms of the accuracy of the inversed LAIs for both FLD and UAV platforms.We conclude that GESAVI and nNDVI2 are the two promising VIs for both platforms and thus preferred for LAI inversion to carry spectra integration of the two platforms.We suggest that accuracy on the LAI inversion could be improved by applying more advanced functions(e.g.non-linear)con-sidering the observed bias for the difference between the UAV-and FLD-inversed LAIs,especially when LAI was low. | Zongyao Sha Yuwei Wang Yongfei Bai Yujin Zhao Hua Jin Ya Na Xiaoliang Meng | 2019 | Journal of Plant Ecology2019，12，3： | 1 |
| 6 | 基于云模型的乡村振兴战略实施效果综合评价显示文摘针对脱贫攻坚与乡村振兴的有效衔接问题,聚焦乡村振兴战略总要求,以农村相对贫困群众为研究对象,对乡村振兴战略的落实效果进行了阶段性评价。首先,采用决策表属性约简与主客观博弈对14个评价指标进行科学赋权以消除感知数据的随机性与主观性,随后结合云模型理论,生成评价综合云图,该方法最大的优势在于能够经过雾化直观展现出群众对乡村振兴战略实施效果的真实评价。其次,立足于群众真实感知视角,基于593份重庆市农村脱贫家庭数据进行实证分析。结果表明,群众对乡村振兴战略评价从高到低依次为:居住条件,村级硬件建设,公平氛围,外部帮扶,温饱改善,程序规范。最后根据研究结论提出一系列针对性的政策建议。 | 陈义安 王斯 杨澈洲 | 2022 | 重庆社会科学2022，，11： | 1 |
| 7 | 基于反射率和亮度温度的锡林郭勒积雪深度估算显示文摘积雪是我国西北干旱半干旱区重要的水资源,也是影响全球气候变化的重要因子之一。目前光学影像反射率和雷达亮温数据是积雪遥感领域的主要数据,本文首次结合两类遥感数据估算积雪深度,并比较偏最小二乘法和机器学习算法(人工神经网络、支持向量机和随机森林算法)在积雪深度估算方面的表现。以锡林郭勒盟2012—2015年积雪深度数据为例,基于反射率和亮度温度相结合的积雪深度估算精度优于单个数据源,且随机森林算法表现最好,均方根误差为2.93 cm,满足实际应用的需求。研究结果对我国西北地区水资源分布、生态环境评估等研究具有重要意义。 | 李慧融 | 2020 | 干旱区地理2020，43，6： | 0 |
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