利用SPOT和ETM+影像进行县级土地利用调查--以河北省万全县为例   总被引：7，自引：0，他引：7  

朱运海 江涛曹银璇  张运生 《四川测绘》2004,27(1):26-29

本文以SPOT和ETM 影像作为主要信息源，经过对图像进行几何纠正、配准、增强和融合等一系列处理后，在ARCVIEW GIS基础上，成功完成了对河北省万全县土地资源利用情况的调查分析。同时还对应用遥感技术成功获取土地资源利用信息的方法和技术进行了探讨。  相似文献   

土地利用动态管理系统研发中的若干问题研究   总被引：2，自引：0，他引：2  

刘志军吴冲龙  马小刚 《四川测绘》2004,27(3):109-112

土地利用管理是土地管理的核心内容之一。土地利用动态变化加剧了土地管理的压力，建设具有辅助决策功能的土地利用动态信息系统是大势所趋。本文在阐述建设此系统的重要意义基础上，讨论了系统研发中几个关键问题，即“动态”管理的实现、空间数据和属性数据集成管理和决策的初步实现等。本文提出的解决方法，对于类似土地信息系统的建设具有普遍的指导意义。  相似文献   

Changes in soil organic carbon and other physical soil properties along adjacent Mediterranean forest, grassland, and cropland ecosystems in Turkey   总被引：4，自引：0，他引：4  

F. Evrendilek  I. Celik  S. Kilic 《Journal of Arid Environments》2004,59(4):811

Cultivation, overgrazing, and overharvesting are seriously degrading forest and grassland ecosystems in the Taurus Mountains of the southern Mediterranean region of Turkey. This study investigated the effects of changes on soil organic carbon (SOC) content and other physical soil properties over a 12-year period in three adjacent ecosystems in a Mediterranean plateau. The ecosystems were cropland (converted from grasslands in 1990), open forest, and grassland. Soil samples from two depths, 0–10 and 10–20 cm, were collected for chemical and physical analyses at each of cropland, open forest, and grassland ecosystems. SOC pools at the 0–20 cm depth of cropland, forest, and grassland ecosystems were estimated at 32,636, 56,480, and 57,317 kg ha⁻¹, respectively. Conversion of grassland into cropland during the 12-year period increased the bulk density by 10.5% and soil erodibility by 46.2%; it decreased SOM by 48.8%, SOC content by 43%, available water capacity (AWC) by 30.5%, and total porosity by 9.1% for the 0–20 cm soil depth (p<0.001). The correlation matrix revealed that SOC content was positively correlated with AWC, total porosity, mean weight diameter (MWD), forest, and grassland, and negatively with bulk density, pH, soil erodibility factor, and cropland. The multiple regression (MLR) models indicated that any two of the three ecosystems and one of the two soil depths accounted for 86.5% of variation in mean SOC values ((p<0.001).  相似文献   

Land subsidence and caprock dolines caused by subsurface gypsum dissolution and the effect of subsidence on the fluvial system in the Upper Tigris Basin (between Bismil–Batman, Turkey)     

Uur Doan 《Geomorphology》2005,71(3-4):389-401

Karstification-based land subsidence was found in the Upper Tigris Basin with dimensions not seen anywhere else in Turkey. The area of land subsidence, where there are secondary and tertiary subsidence developments, reaches 140 km². Subsidence depth ranges between 40 and 70 m. The subsidence was formed as a result of subsurface gypsum dissolution in Lower Miocene formation. Although there are limestones together with gypsum and Eocene limestone below them in the area, a subsidence with such a large area is indicative of karstification in the gypsum. The stratigraphical cross-sections taken from the wells and the water analyses also verify this fact. The Lower Miocene gypsum, which shows confined aquifer features, was completely dissolved by the aggressive waters injected from the top and discharged through by Zellek Fault. This resulted in the development of subsidence and formation of caprock dolines on loosely textured Upper Miocene–Pliocene cover formations. The Tigris River runs through the subsidence area between Batman and Bismil. There are four terrace levels as T1 (40 m), T2 (30 m), T3 (10 m) and T4 (4–5 m) in the Tigris River valley. It was also found that there were some movements of the levels of the terraces in the valley by subsidence. The subsidence developed gradually throughout the Quaternary; however no terrace was formed purely because of subsidence.  相似文献   

Land degradation in the source region of the Yellow River, northeast Qinghai-Xizang Plateau: classification and evaluation   总被引：6，自引：0，他引：6  

Jianmin Feng  Tao Wang  Shanzhong Qi  Changwei Xie 《Environmental Geology》2005,47(4):459-466

Land degradation imposes a great threat to the world. It is not merely an environmental issue, but also a social and economic problem. Land desertification is among the main aspects of environment changes in the source region of the Yellow River. Previous studies focused on water resource utilization and soil erosion, but land degradation in the source region of the Yellow River even the whole Qinghai-Xizang Plateau received little attention. Based on the data obtained by field investigation and TM satellite images of 2000, this study provides the classification and evaluation information of the land degradation in the source region of the Yellow River. There are six types of land degradation in this region: water erosion in the northern mountains around the Gonghe Basin, sandy desertification in the Gonghe Basin and Upland Plain Area, aridization in the lower reaches, salinization in the Gonghe Basin, vegetation degradation in the intramontance basin and freezing and thawing erosion in the high mountains. The total degraded area is 34,429.6 km², making up 37.5% of the land in the study area. Finally, land degradation in the source region of the Yellow River was evaluated according to changes in the physical structure and chemical component of soils, land productivity, secondary soil salt and water conditions.  相似文献   

Landscape change and sandy desertification in arid areas: a case study in the Zhangye Region of Gansu Province, China   总被引：3，自引：0，他引：3  

F. Luo  S. Z. Qi  H. L. Xiao 《Environmental Geology》2005,49(1):90-97

The Zhangye Region of Gansu Province is an important agricultural base in arid northwestern China. During the twentieth century, especially in the last five decades, the region has experienced sandy desertification. To document the status and causes of this deterioration, satellite images, meteorological and socioeconomic data to assess landscape change from 1993 to 2002 were interpreted and analyzed. The results show that during the intervening 9-year period the area of sandy lands has increased by 642.2 km², which consist of aeolian sand dune (357.1 km²) and potential sandy land (216.3 km²). Although the development and reversion of sandy desertification co-exist, the sandy desertification in this area seems serious and is attributable to the irrational use of water and land.  相似文献   

Environmental significance of C/C and O/O ratios of modern land-snail shells from the southern great plains of North America     

Meena Balakrishnan  James L. Theler  Don G. Wyckoff 《Quaternary Research》2005,63(1):15-30

¹³C/¹²C and ¹⁸O/¹⁶O ratios of aragonite shells of modern land snails from the southern Great Plains of North America were measured for samples from twelve localities in a narrow east-west corridor that extended from the Flint Hills in North Central Oklahoma to the foothills of the Sangre de Cristo Mountains in Northern New Mexico, USA. Across the study area, shell δ¹⁸O values (PDB scale) ranged from −4.1‰ to 1.2‰, while δ¹³C values ranged from −13.2‰ to 0.0‰. δ¹⁸O values of the shell aragonite were predicted with a published, steady state, evaporative flux balance model. The predicted values differed (with one exception) by less than 1‰ from locality averages of measured δ¹⁸O values. This similarity suggests that relative humidity at the time of snail activity is an important control on the δ¹⁸O values of the aragonite and emphasizes the seasonal nature of the climatic information preserved in the shells. Correlated δ¹³C values of coexisting Vallonia and Gastrocopta suggest similar feeding habits and imply that these genera can provide information on variations in southern Great Plains plant ecology. Although there is considerable scatter, multispecies, transect average δ¹³C values of the modern aragonite shells are related to variations in the type of photosynthesis (i.e., C₃, C₄) in the local plant communities. The results of this study emphasize the desirability of obtaining isotope ratios representing averages of many shells in a locale to reduce possible biases associated with local variations among individuals, species, etc., and thus better represent the “neighborhood” scale temporal and/or spatial environmental variations of interest in studies of modern and ancient systems.  相似文献   

固沙林庇护区内降尘特征的初步观测   总被引：2，自引：1，他引：2  

张华  何红  李锋瑞 《干旱区地理》2005,28(2):156-160

采用野外定位实测法,连续两年对科尔沁沙地24龄人工固沙杨树(Populussimonii)林庇护区内4～6月份及强沙尘暴事件中的降尘特征进行了观测研究。结果表明:(1)林地庇护区内4、5月份的降尘量较多,分别为273和437kg/hm2,6月份的降尘量较少,为171kg/hm2。(2)林地中央的滞尘效应在风蚀季节和强沙尘暴天气过程中十分显著。(3)林地庇护区内的降尘中粒径<0.02mm颗粒含量占60.7%,降尘中的全C、全N和速效P含量分别高达1.676%、0.163%和210.66mg/kg,这对风沙土表层土壤的细化和养分的积累具有重要的生态学意义。  相似文献   

A global review of the impact of forest property rights interventions on poverty     

《Global Environmental Change》2021

Secure property rights are widely understood as critical for socio-economic development and sustainable land management in forested areas. Policies and programs, ranging from devolution of specific resource rights to formal land titling, have therefore been implemented to strengthen forest tenure and property rights in countries around the world. Despite the prevalence and importance of these efforts, however, systematic understanding of their effects on poverty remains lacking. We address this gap by systematically reviewing evidence on the impact of forest property rights interventions on poverty worldwide. We drew from a systematic map of evidence on forest-poverty links (Cheng et al., 2019) and used a population-intervention-comparator-outcome (PICO) framework to identify relevant studies. Our final dataset included 61 articles published from 2002 to 2016 comprising 91 case studies across 24 countries. Of these, only 11 articles (22 cases) used quasi-experimental methods to control for confounders. We find that almost all studied interventions (n = 88; 97%) focused on rights to access a forest area or withdraw resources from it. Relatively few studied interventions supported the more extensive property rights of exclusion (32%) and alienation (10%). Overall, reported impacts on both income/consumption and capital/assets dimensions of poverty were generally positive or mixed. Results from more robust quasi-experimental assessments showed greater variation, with case studies as likely to report negative as positive impacts on both poverty dimensions. We find tentative support for the economic theory that more secure property rights yield positive welfare effects. However, the paucity of evidence from more robust impact assessments constrains our ability to draw generalizable conclusions about the poverty impacts of different kinds of forest property rights interventions.  相似文献   

Historical paths to current unrest: Extending the temporal lens in analysing geographies of agrarian change and conflict     

《Geoforum》2016

The proliferation of soybean monoculture and its expansion into previously marginal territories in Argentina have resulted in land conflicts and attacks on peasant communities that possess land without having secured tenure. However, the rapid and intensive modernisation and industrialisation of agriculture production has had differentiated effect on different territories in Argentina. This article posit that understanding these differences requires an extended temporal analysis. While social research tends to focus on the present or recent past, this paper joins calls for greater attention to historical context and processes when examining current social dynamics and geographies. Focusing on the province of Santiago del Estero in Northwest Argentina, this paper provides a particular temporal-thematic approach for conducting such a historical path analysis, which here focuses on the province’s changing agrarian structures and political shifts that resulted in a complex, irregular and subsequently unstable land tenure system.  相似文献