检索结果-南通市图书馆

Quantifying spatial scale of positive and negative terrains pattern at watershed-scale:Case in soil and water conservation region on Loess Plateau

引用

Journal of Mountain Science 2017年第8期14卷 1642-1654页

作者： YANG Feng ZHOU Yi school of geography and tourism Shaanxi Normal University

The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis(TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches(e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction(i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern alsoclearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors(i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China' Loess Plateau, it is crucial to u

关键词： Positive and negative terrains TTLQV Spatial pattern scale Loess landforms Loess Plateau

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Changes in the depths of seasonal freezing and thawing and their effects on vegetation in the Three-River Headwater Region of the Tibetan Plateau

引用

Journal of Mountain Science 2019年第12期16卷 2810-2827页

作者： WANG Rui DONG Zhi-bao ZHOU Zheng-chao school of geography and tourism Shaanxi Normal University

Frozen ground degradation plays an important role in vegetation growth and activity in high-altitude cold *** study estimated the spatiotemporal variations in the active layer thickness(ALT)of the permafrost region and the soil freeze depth(SFD)in the seasonally frozen ground region across the Three Rivers Source Region(TRSR)from 1980 to 2014 using the Stefan equation,and differentiated the effects of these variations on alpine vegetation in these two *** results showed that the average ALT from 1980 to 2014 increased by23.01 cm/10 a,while the average SFD decreased by 3.41 cm/10 a,and both changed intensively in the transitional zone between the seasonally frozen ground and *** 1982-2014,the increase in the normalized difference vegetation index(NDVI)and the advancement of the start of the vegetation growing season(SOS)in the seasonally frozen ground region(0.0078/10 a,1.83 d/10 a)were greater than those in the permafrost region(0.0057/10 a,0.39 d/10 a).The results of the correlation analysis indicated that increases in the ALT and decreases in the SFD in the TRSR could lead to increases in the NDVI and advancement of the *** soil moisture played a critical role in vegetation growth in association with the increasing ALT and decreasing *** NDVI for all vegetation types in the TRSR except for alpine vegetation showed an increasing trend that was significantly related to the SFD and *** the study period,the general frozen ground conditions were favorable to vegetation growth,while the average contributions of ALT and SFD to the interannual variation in the NDVI were greater than that of precipitation but less than that of temperature.

关键词： Frozen soil depth Active layer thickness Alpine vegetation Climate warming Three Rivers Source Region

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Predicting and assessing changes in NPP based on multi-scenario land use and cover simulations on the Loess Plateau

引用

Journal of Geographical Sciences 2021年第7期31卷 977-996页

作者： JIANG Xiaowei BAI Jianjun school of geography and tourism Shaanxi Normal UniversityXi'an 710119China

Land use/cover change(LUCC)is a major factor affecting net primary production(NPP).According to the LUCC of the Loess Plateau from 2005 to 2015,the LUCC patterns in 2025 in three scenarios were predicted by using the Future Land Use Simulation(FLUS)***,taking the average NPP of various land use/cover types in 16 years as the reference scale,the changes in NPP in multi-scenario simulations are predicted and analyzed,and the impact of different land use/cover transfers on NPP is *** results are as follows:(1)The land use/cover changes greatly in the baseline and fast development scenarios,and changes relatively little in the ecological protection scenarios.(2)The changes in NPP in different scenarios reflected the significant difference in the ecological protection *** the three scenarios promote an NPP increase,but the ecological protection scenario can promote NPP increases the most.(3)The changes in NPP caused by LUCC in the three scenarios reflected the significant difference in the various land use/cover types protection *** and predicting NPP changes in multi-scenario LUCC simulations in the future can provide a theoretical basis for decision makers to judge the future changes in ecological environments and ecological protection effects against different policy backgrounds.

关键词： net primary production(NPP) scenario simulation land use/cover change(LUCC) Loess Plateau

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The spatio-temporal heterogeneity of county-level economic development and primary drivers across the Loess Plateau,China

引用

Journal of Geographical Sciences 2021年第3期31卷 423-436页

作者： LIU Shijun XUE Liang school of geography and tourism Shaanxi Normal UniversityXi'an 710119China

Unbalanced economic growth is a ubiquitous phenomenon while investigating the regional development at a large spatial ***,it is of great significance to analyze the spatio-temporal pattern of regional economic growth and the drivers to understand and facilitate the economic development of low development *** a county as a fundamental study unit,we used the county-level per capita GDP data on the Loess Plateau from 2005 to 2017,and geographic variables such as slope,elevation,and population density to analyze the spatio-temporal differences and the driving factors of the county-level economic development in the Loess Plateau by employing both conventional and advanced quantitative methods including Exploratory Spatial Data Analysis(ESDA)and the geographic detector *** results suggested that:(1)The selected indicators,including absolute difference,the fluctuation of relative difference and total difference of economic development on the Loess Plateau,all show steady increasing trends,respectively.(2)There are 64.5%of the counties with economic development being below the average level of the whole Loss Plateau *** relatively high developed counties are distributed in the"A"-shaped regions in Inner Mongolia Autonomous Region,Shaanxi,and Henan provinces,however,the low development counties are mainly located in the"V"-shaped regions in Gansu and Shanxi provinces.(3)GDP,investment in fixed assets and urbanization rate are the major driving factors influencing the regional economic development,and the combined effects are far greater than that of any individual factor.

关键词： county economic development difference driving factor Loess Plateau

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Different Responses of Vegetation to Frozen Ground Degradation in the Source Region of the Yellow River from 1980 to 2018

引用

Chinese Geographical Science 2020年第4期30卷 557-571页

作者： WANG Rui DONG Zhibao ZHOU Zhengchao school of geography and tourism Shaanxi Normal UniversityXi'an 710119China

Frozen ground degradation under a warming climate profoundly influences the growth of alpine vegetation in the source region of the Qinghai-Tibet *** study investigated spatiotemporal variations in the frozen ground distribution,the active layer thickness(ALT)of permafrost(PF)soil and the soil freeze depth(SFD)in seasonally frozen soil from 1980 to 2018 using the temperature at the top of permafrost(TTOP)model and Stefan *** compared the effects of these variations on vegetation growth among different frozen ground types and vegetation types in the source region of the Yellow River(SRYR).The results showed that approximately half of the PF area(20.37%of the SRYR)was projected to degrade into seasonally frozen ground(SFG)during the past four decades;furthermore,the areal average ALT increased by 3.47 cm/yr,and the areal average SFD decreased by 0.93 cm/yr from 1980 to ***,the growing season Normalized Difference Vegetation Index(NDVI)presented an increasing trend of 0.002/10 yr,and the increase rate and proportion of areas with NDVI increase were largest in the transition zone where PF degraded to SFG(the PF to SFG zone).A correlation analysis indicated that variations in ALT and SFD in the SRYR were significantly correlated with increases of NDVI in the growing ***,a rapid decrease in SFD(<-1.4 cm/10 yr)could have reduced the soil moisture and,thus,decreased the *** NDVI for most vegetation types exhibited a significant positive correlation with ALT and a negative correlation with ***,the steppe NDVI exhibited a significant negative correlation with the SFD in the PF to SFG zone but a positive correlation in the SFG zone,which was mainly limited by water condition because of different change rates of the SFD.

关键词： permafrost seasonally frozen ground vegetation dynamics climate change source region of the Yellow River

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Quantitative assessment of the spatial distribution of^(239+240)Pu inventory derived from global fallout in soils from Asia and Europe

引用

Journal of Geographical Sciences 2022年第4期32卷 605-616页

作者： CAO Liguo ZHOU Zhengchao WANG Ning XIAO Shun school of geography and tourism Shaanxi Normal UniversityXi'an 710119China

Due to the atmospheric nuclear weapon tests carried out,terrestrial environments have been extensively contaminated by global fallout of plutonium(Pu)***^(239+240)Pu inventories in soil profiles from undisturbed and flat forest or grasslands(reference sites)mainly from Europe and Asia are considered as important background for evaluating soil ***,we conducted a literature survey over an area extending from 2.6°W to 148.9°E and from 53.2°S to 76.6°N,with the purpose of analyzing the spatial distribution of^(239+240)Pu inventories and possible controlling *** aim of this work was to derive an empirical model of^(239+240)Pu inventory based on currently available^(239+240)Pu data,precipitation and *** results show that,in general,the latitudinal distribution of^(239+240)Pu inventory was consistent with the UNSCEAR ***,the^(239+240)Pu inventories are higher than the UNSCEAR data,especially in the Northern *** addition,close relationships(at the 0.01 significance level)were identified between^(239+240)Pu inventories and annual precipitation and *** empirical formula was therefore developed to estimate^(239+240)Pu inventories in soils based on latitude and precipitation ***,future research may require more data of measured^(239+240)Pu inventories in soil profiles that can be used to compare,validate and improve upon the accuracy of the inferred empirical equation.

关键词： spatial distribution plutonium global fallout precipitation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Projected Regional 1.50℃and 2.00℃Warming Threshold-crossing Time Worldwide Using the CMIP6 Models

引用

Chinese Geographical Science 2023年第6期33卷 1095-1108页

作者： MENG Yali DUAN Keqin SHANG Wei SHI Peihong LI Shuangshuang CHENG Ying CHEN Rong ZHANG Zhaopeng school of geography and tourism Shaanxi Normal UniversityXi’an710119China

The Paris Agreement aims to limit global warming to well below 2.00℃and pursue efforts to limit the temperature increase to 1.50℃.However,the response of climate change to unbalanced global warming is affected by spatial and temporal *** better understand the regional warming response to global warming at 1.50℃and 2.00℃,we detected the 1.50℃and 2.00℃warming threshold-crossing time(WTT)above pre-industrial levels globally using the Coupled Model Intercomparison Project phase 6(CMIP6)*** findings indicate that the 1.50℃or 2.00℃WTT differs substantially *** warming rate of land would be approximately 1.35–1.46 times that of the ocean between 60°N–60°S in 2015–***,the land would experience a 1.50℃(2.00℃)warming at least 10–20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50℃(2.00℃)***,the Southern Ocean between 0°and 60°S considerably slows down the global 1.50℃and 2.00℃*** 2040–2060,over 98.70%(77.50%),99.70%(89.30%),99.80%(93.40%),and 100.00%(98.00%)of the land will have warmed by over 1.50℃(2.00℃)under SSP(Shared Socioeconomic Pathway)1–2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5,*** conclude that regional 1.50℃(2.00℃)WTT should be fully considered,especially in vulnerable high-latitude and high-altitude regions.

关键词： CMIP6(Coupled Model Intercomparison Project phase 6) global warming 1.50℃warming time 2.00℃warming time regional differences

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Source-sink landscape spatial characteristics and effect on non-point source pollution in a small catchment of the Three Gorge Reservoir Region

引用

Journal of Mountain Science 2018年第2期15卷 327-339页

作者： WANG Jin-liang NI Jiu-pai CHEN Cheng-long XIE De-ti SHAO Jing-an CHEN Fang-xin LEI Ping school of Resources and Environment Southwest University school of geography and tourism Chongqing Normal University

The source and sink landscape patterns refer to landscape types or units that can either promote positive evolvement of non-point source(NPS) pollution process, or can prevent/defer the ecological process, respectively. Therefore, the role of a catchment landscape pattern in nutrient losses can be identified based on the spatial arrangement of source and sink landscapes. To reveal the relations between landscape spatial characteristics and NPS pollution in small catchment, a case study was carried out in a Wangjiagou small catchment of the Three Gorges Reservoir Region(TGRR), China. Google earth imagery for 2015 were processed and used to differentiate source and sink landscape types, and six subcatchments were selected as sample regions for monitoring nitrogen and phosphorus *** elevation, slope gradient and relative flow length was used to construct the Lorenz curves of different source and sink landscape types in the catchment, in order to assess the source and sink landscape spatial characteristics. By calculating the location-weighted landscape indices of each subcatchment and total catchment, the landscape spatial load characteristics affecting the NPS pollution was identified, with a further Pearson correlation analysis for location-weighted landscape indices and nitrogen-phosphorus monitoring indicators. The analysis of Lorenz curve has revealed that the obtained distribution trend of Lorenz curve and curve area quantified well the spatial characteristics of source and sink landscape pattern related to the relative elevation, slope gradient and relative flow length in small catchment. Results of Pearson correction analysis indicated that location-weighted landscape index(LWLI) combining of terrain and landscape type factor did better in reflecting the status of nitrogen and phosphorus loss than the indices related to relative elevation, slope gradient and relative flow length.

关键词： Source-sink landscape Non-point sourcepollution Nutrient loss Lorenz curve Landscapeindex Small catchment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Land cover change and eco-environmental quality response of different geomorphic units on the Chinese Loess Plateau

引用

Journal of Arid Land 2020年第1期12卷 29-43页

作者： SONG Yongyong XUE Dongqian DAI Lanhai WANG Pengtao HUANG Xiaogang XIA Siyou school of geography and tourism Shaanxi Normal UniversityXi'an 710119China school of tourism&Research Institute of Human geography Xi'an International Studies UniversityXi'an 710128China school of geography Science Nanjing Normal UniversityNanjing 210023China

Land cover in the Chinese Loess Plateau has undergone dramatic changes since the late *** the trend in land cover change and eco-environmental quality response of different geomorphic units in this stage is a realistic requirement for promoting sustainable development of the Chinese Loess *** on the data of geomorphic units and land cover in 1990,2000,2010 and 2018 of the Chinese Loess Plateau,we studied the trend of land cover change and eco-environmental quality response of different geomorphic units by using a significance index of land cover change,a proportion index of land cover change and an eco-environmental response *** results indicated that from 1990 to 2018,the areas of forestland and construction land substantially increased,whereas those of cropland,grassland,wetland and unused land considerably *** cover change exhibited large geomorphic differences,and the main conversion of land cover was from cropland into other land *** trend of land cover change in the loess tablelands and sandy loess hills declined,whereas the unstable trends in the other geomorphic units ***-environmental quality varied among different geomorphic *** expansion of construction land and degradation of forestland,grassland and wetland resulted in the deterioration of eco-environmental *** conversion of cropland and unused land into forestland and grassland,and the conversion of grassland into forestland were the main factors that drove the improvement of eco-environmental *** findings of this study may provide theoretical reference and support decision making for the optimization of land use structure and the improvement of eco-environmental quality on the Chinese Loess Plateau.

关键词： cropland degradation eco-environmental quality index grassland human activity unused land relative ecological value

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Contribution of underlying terrain to sand dunes: evidence from the Qaidam Basin, Northwest China

引用

Journal of Arid Land 2021年第12期13卷 1215-1229页

作者： LI Jiyan QU Xin DONG Zhibao CAI Yingying LIU Min REN Xiaozong CUI Xujia school of geography Science Taiyuan Normal UniversityJinzhong 030619China school of geography and tourism Shaanxi Normal UniversityXi'an 710119China

Underlying terrain strongly influences dune ***,the impacts of underlying terrain on the dune formation are poorly *** the present research,we focused on dunes that formed in the alluvial fans and dry salt flats in the Qaidam Basin,Northwest *** quantified the dunes'sediment characteristics on different types of underlying terrain and the terrain's effects on the surface quartz grains by analyzing grain-size distribution,soluble salt contents and grain surface *** showed that barchan dunes were dominated by medium sands with a unimodal frequency distribution,whose peak corresponded to the saltation *** dunes were mainly composed of fine sands with a bimodal frequency distribution,whose main peak represented the saltation load,and whose secondary peak represented the modified saltation or suspension *** was transported from source area by running water(inland rivers)over short distances and by wind over relatively longer ***,quartz grains had poor roundness and were dominated by sub-angular and angular *** micro-textures indicated that dune sands were successively transported by exogenic agents(glaciation,fluviation and wind).Soluble salt contents were low in dunes that developed in the alluvial fans,which represented a low-energy chemical environment,so the grain surface micro-textures mainly resulted from mechanical erosion,with weak micro-textures formed by SiO2 solution and ***,soluble salt contents were much higher in dunes that developed in the dry salt flats,which indicated a high-energy chemical ***,in addition to micro-structures caused by mechanical erosion,micro-textures formed by SiO2 solution and precipitation also well *** results improve understanding of the sediment characteristics of dune sands and the effects of underlying terrain on dune development in the Qaidam Basin,China.

关键词： dune grain-size distribution soluble salts surface micro-texture Qaidam Basin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：