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1.
The prehistoric and preindustrial deforestation of Europe   总被引:1,自引:0,他引:1  
Humans have transformed Europe's landscapes since the establishment of the first agricultural societies in the mid-Holocene. The most important anthropogenic alteration of the natural environment was the clearing of forests to establish cropland and pasture, and the exploitation of forests for fuel wood and construction materials. While the archaeological and paleoecological record documents the time history of anthropogenic deforestation at numerous individual sites, to study the effect that prehistoric and preindustrial deforestation had on continental-scale carbon and water cycles we require spatially explicit maps of changing forest cover through time. Previous attempts to map preindustrial anthropogenic land use and land cover change addressed only the recent past, or relied on simplistic extrapolations of present day land use patterns to past conditions. In this study we created a very high resolution, annually resolved time series of anthropogenic deforestation in Europe over the past three millennia by 1) digitizing and synthesizing a database of population history for Europe and surrounding areas, 2) developing a model to simulate anthropogenic deforestation based on population density that handles technological progress, and 3) applying the database and model to a gridded dataset of land suitability for agriculture and pasture to simulate spatial and temporal trends in anthropogenic deforestation. Our model results provide reasonable estimations of deforestation in Europe when compared to historical accounts. We simulate extensive European deforestation at 1000 BC, implying that past attempts to quantify anthropogenic perturbation of the Holocene carbon cycle may have greatly underestimated early human impact on the climate system.  相似文献   

2.
Along with the increase of population and extraordinary economic and social development, human appropriation of freshwater supply increases rapidly. Anthropogenic activities have become an important driving factor of the large-scale terrestrial water cycle. The hydrological effects of human water use have attracted growing attention. In this paper, we briefly reviewed the recent studies addressing the anthropogenic disturbance of the large-scale terrestrial water cycle. The review focused on the direct alteration of the water cycle for human needs, with special coverage for the primary aspects of human water use such as irrigation, domestic and industrial water use, reservoir regulation and groundwater mining. The state-of-the-art parameterization schemes of human water use for macroscale land surface hydrological modeling were introduced and the limitations of the schemes were discussed. Considering the impacts of human water use on the terrestrial water cycle is currently a challenge for macroscale land surface hydrological modeling, which hinders the use of the models in assessing water resources under changing environment. Further studies are needed to understand the interactions between human and water systems, to develop integrated assessment model of coupled human-water systems, and to assess regional and global water security.  相似文献   

3.
Conservation efforts often neglect the importance of monitoring of protected areas, which is key to adaptively managing dynamic landscapes. In many developing countries, like Trinidad, protected areas are set aside as a result of an agreement with an international conservation organization, often resulting in inadequate planning and monitoring of the protected area. Monitoring of protected areas allows for an examination of the conservation scheme implemented and enables improved conservation decisions to be made. The research presented provides an example of the use of technology in monitoring conservation strategies in two protected wetlands, Caroni and Nariva, in Trinidad. Remote sensing and fragmentation analyses are used to quantify land cover change within these two protected wetlands. Results show that the classification of Caroni immediately identifies a shift towards anthropogenic land cover types, suggesting an increase in human activity within the park. This finding is further supported by the continuous measures used, such as decreases in mean NDVI and greenness values suggesting a decrease in the amount or health of the vegetation. While the classification of Nariva suggests a return to natural land covers, the continuous measures of land cover change indicate the opposite. Land cover change analyses are limited in Trinidad and in the Caribbean in general, partly due to satellite data availability, thus this research presents remote sensing and landscape fragmentation analyses as new tools for monitoring land cover change and conservation effectiveness in Trinidad.  相似文献   

4.
区域土地利用变化驱动力研究前景展望   总被引:29,自引:0,他引:29  
区域土地利用变化驱动力研究旨在从典型区域角度揭示土地利用变化背后的真正动因及其作用机理,进而动态模拟、预测区域土地利用变化过程。土地利用系统的自组织性及其内驱动因子作用的复杂性,决定了其研究必须与某一特定区域相联系,以便确定合适的可定量指标来体现外生驱动因子的驱动效果。系统地识别土地利用系统在不同控制状态下的驱动因子及其多种时空尺度效应,建立具有综合模拟的区域土地利用变化动态模型,能减少土地利用系统通常受临界值域和突变所左右的局面。区域土地利用变化驱动因子识别、区域土地利用变化驱动机制分析、区域土地利用变化驱动过程模拟等的研究现状表明,为更好地理解区域土地利用变化的机制和原因,测度现有及未来土地利用变化的速率、过程和地点,支持政府相关决策的制定与实施,促使区域土地利用变化向有利于人类的方向发展,区域土地利用变化驱动力分析应优先考虑以下研究领域:①驱动力因子识别及其作用效应的尺度依赖性;②驱动力因子的贡献量化及其在具体区域的非均一分布;③驱动力因子作用过程的自然反馈机制模型化。 [HT5H]关〓键〓词:[HT5K]  相似文献   

5.
The change in the tropical forests could be clearly linked to the expansion of the human population and economies. An understanding of the anthropogenic forcing plays an important role in analyzing the impacts of climate change and the fate of tropical forests in the present and future scenario. In the present study, we analyze the impact of natural and anthropogenic factors in forest dynamics in Katerniaghat wildlife sanctuary situated along the Indo-Nepal border in Uttar Pradesh state, India. The study site is under tremendous pressure due to anthropogenic factors from surrounding areas since last three decades. The vegetation cover of the sanctuary primarily comprised of Shorea robusta forests, Tectona grandis plantation, and mixed deciduous forest; while the land cover comprised of agriculture, barren land, and water bodies. The classification accuracy was 83.5%, 91.5%, and 95.2% with MSS, IKONOS, and Quickbird datasets, respectively. Shorea robusta forests showed an increase of 16 km2; while Tectona grandis increased by 63.01 km2 during 1975–2010. The spatial heterogeneity in these tropical vegetation classes surrounded by the human dominated agricultural lands could not be addressed using Landsat MSS data due to coarse spatial resolution; whereas the IKONOS and Quickbird satellite datasets proved to advantageous, thus being able to precisely address the variations within the vegetation classes as well as in the land cover classes and along the edge areas. Massive deforestation during 1970s along the adjoining international boundary with Nepal has led to destruction of the wildlife corridor and has exposed the wildlife sanctuary to human interference like grazing and poaching. Higher rates of forest dynamics during the 25-year period indicate the vulnerability of the ecosystem to the natural and anthropogenic disturbances in the proximity of the sanctuary.  相似文献   

6.
土地结构与土地演替研究   总被引:6,自引:0,他引:6  
在以往对黄土高原和秦巴山地等地区土地研究的基础上,提出土地结构是土地空间组合格局与土地演替及土地时间变化规律的观点;分析了土地质与量群聚的对比关系和
土地由一种属性转变为另一种属性的过程;用信息论中的熵函数给出了土地出现的频率和复杂度;用耗散结构理论“涨落”给出了土地自然演替(不可逆)和人为演替(可逆)两种演
替模式。
     相似文献   

7.
Dawn C. Parker  Amy Hessl 《Geoforum》2008,39(2):789-804
Land-use systems are characterized by complex interactions between human decision-makers and their biophysical environment. Mismatches between the scale of human drivers and the impacts of human decisions potentially threaten the ecological sustainability of these systems. This article reviews sources of complexity in land-use systems, moving from the human decision level to human interactions to effects over space, time and scale. Selected challenges in modeling such systems and potential resolutions are discussed, including strategies to empiricize complex models and methods for linking models across human and natural systems. Illustrative examples from published literature and an ongoing research project focused on timber harvest and carbon sequestration are used throughout the paper. The paper concludes with a brief discussion of remaining challenges to modeling indirect and cross-scale linkages and of the potential utility of complex models of land systems.  相似文献   

8.
气候变化对陆地水循环影响研究的问题   总被引:29,自引:5,他引:24  
简要地回顾了现存的由气候情景驱动水文模型研究气候变化对陆地水循环影响的方法。指出这种单向连接方法很难将气候变暖及人类活动引起的陆地水循环变化反馈给大气。这既影响对降雨的预测精度,又不能正确地描写陆地水循环的变化。近10年来气候学家对大气环流模型中陆面过程模型的改进以及水文气候学家对大尺度水文模型研究所取得的进展,展现了它们之间的互补性,以及未来用水文-气候耦合模型方法研究气候变化与人类活动对陆地水循环影响及水资源预测的可能性。  相似文献   

9.
To manage dryland salinity, one needs to know how changed land use affects groundwater recharge. Few techniques are available for comparing 'deep drainage' under different land uses. Soil-tracer methods, although good for replication and remote field sites, are subject to spatial variability. Lysimeters are good for comparisons but are difficult for drier areas and sloping land. Agronomic water-balance studies, where appropriate soil-water measurements exist, may be used with a soil-vegetation model to estimate long-term deep drainage. Complex models are required to analyze specific land-use differences, such as perenniality and root and leaf area dynamics, but models require intensive and extensive data for calibration. This approach is time-consuming, labour-intensive, and difficult in remote locations. Because of the one-dimensionality of most soil-vegetation models and the small fraction of the total water balance that is deep drainage, little success has occurred in extrapolating beyond the research plot, or to spatially heterogeneous systems such as alley farming. Some 'top-down' modelling and landscape disaggregation approaches have been partially successful in making catchment or regional-scale predictions. The direction for further work depends on the level of recharge reduction that is required for most groundwater systems and difficulties that it imposes. Electronic Publication  相似文献   

10.
农业土地利用对岩溶地下水影响研究综述   总被引:4,自引:4,他引:0  
贾亚男 《中国岩溶》2003,22(4):306-312
地球表层系统最突出的景观标志是土地利用/土地覆被。人类通过土地利用改变天然土地覆被从而对脆弱敏感的岩溶水文系统产生了重大的影响。文章着重从农业土地利用出发综述了当前农业土地利用对岩溶水影响的研究。农业土地利用对岩溶地下水的影响主要围绕着水质和水量两个核心从以下几个方面展开:天然植被的清除,农业灌溉和排水,农业集约化所带来的化肥杀虫剂等的使用以及污染物质在岩溶含水层中的运移和影响。在此基础上作者从研究内容,理论方法和建立模型等方面都提出了自己的想法和建议。   相似文献   

11.
We examined the anthropogenic and natural causes of flood risks in six representative cities in the Gangwon Province of Korea. Flood damage per capita is mostly explained by cumulative upper 5% summer precipitation amount and the year. The increasing flood damage is also associated with deforestation in upstream areas and intensive land use in lowlands. Human encroachment on floodplains made these urban communities more vulnerable to floods. Without changes in the current flood management systems of these cities, their vulnerability to flood risks will remain and may even increase under changing climate conditions.  相似文献   

12.
In many countries worldwide, similar state policies on land management have been implemented as a response to deforestation in mountainous areas. So far, few studies have examined to which extent these policies have actually contributed to reforestation. This is the focus of our analysis, based on a case study in Vietnam. Because land access and land use were traditionally governed by common rules, we examine land use changes from an institutional perspective. We use the Institutional Analysis and Development (IAD) framework, coupled with an historical perspective and the analysis of actors’ perception and dominant narratives on land management and forests. Results show that national policies significantly interfered with local factors, leading to a complex course of decision-making and action. Substantial reforestation in the area was not a response by farmers to policy incentives but rather the unexpected outcome of the disruption of local institutions by these policies. We argue that, because national interventions have relied on false or exaggerated narratives and beliefs, their implementation is in conflict with the local reality in upland areas, leading to unpredictable and locally dependent outcomes. We defend hence the need for local level studies and also recommend considering local institutions for land use change analysis in contexts where land use systems are characterised by a high degree of human interaction.  相似文献   

13.
In many metropolitan regions, natural sources contribute a substantial fraction of volatile organic compound (VOC) emissions. These biogenic VOC emissions are precursors to tropospheric Ozone (O3) formation. Because forests make up 59% of the land area in Taiwan Province, China, the biogenic VOC emissions from forests and farmland could play an important role in photochemical reactions. On the other hand, anthropogenic emissions might also be one of the major inputs for ground level O3 concentrations. Hence, emission inventory data, grouped as point, area, mobile and biogenic VOC sources, are a composite of reported and estimated pollutant emission information and are used by many air quality models to simulate ground level O3 concentrations. Before using relevant air quality models, the emission inventory data generally require huge amounts of processing for spatial, temporal, and species congruence with respect to the associated air quality modeling work. The fist part of this research applied satellite remote sensing and geographic information system (GIS) analyses to characterize land use/land cover (LULC) patterns, integrating various sources of anthropogenic emissions and biogenic emissions associated with a variety of plant species. To investigate the significance of biogenic VOC emissions on ozone formation, meteorological and air quality modeling were then employed to generate hourly ozone estimates for a case study of a high ozone episode in southern Taiwan, which is the leading industrial hub on the island. To enhance the modeling accuracy, a unique software module, SMOKE, was set up for emission processing to prepare emission inputs for the U.S. EPA’s Models-3/CMAQ. An emission inventory of Taiwan, TEDS 4.2, was used as the anthropogenic emission inventory. Biogenic emission modeling was accomplished by BEIS-2 in SMOKE, with improvement of local LULC data and revised emission factors. Research findings show that the majority of biogenic VOC emissions occur in the mountainous areas and farmlands. However, the modeling outputs show that downwind of the most heavily populated and industrialized areas, these biogenic VOC emissions have less impact on air quality than do anthropogenic emissions.  相似文献   

14.
The leading role of water and its interactions with other key environmental elements was well understood already in Antique time. Due to the later fragmentarization of science, this leading role seems to have become hidden, if not neglected. Today, both life-support systems and the productivity of land and water systems are increasingly threatened by human pressure, influencing water availability, water-related land productivity, water quality and productivity of aquatic ecosystems. The world may in fact be approaching or even overshooting its carrying capacity in certain regions, producing quite dangerous conditions. Basically, the anthropogenic influences from a rapidly growing world population with rising demands will produce a reshaped landscape with altered ways of functioning, and a growing water crowding.Paying due attention to water phenomena and functions, this modified landscape has to be analyzed to identify the new strategies by which life support can be managed in the future. A conceptual base is urgently needed, addressing both natural and anthropogenic conditions and phenomena. In follow up of Agenda 21, the paper focuses on landscape analysis for the integration of land and water. It analyzes the main natural components of landscape systems and the ways in which the determinants are being influenced by human activities. A multitude of different interactions between land characteristics and water phenomena are identified. Due to the integrity of the water cycle, these interactions will have to be synthesized and integrated. When the natural funtions of a particular landscape are known, together with the anthropogenic pressure and the various influences from which it is composed, the landscape analysis in this paper may be useful in support of planning, projection and conceptualization of landscape management and spatial organization of land.  相似文献   

15.
减缓全球变暖与温室气体吸收汇研究进展   总被引:28,自引:8,他引:20  
对减缓全球气候变化与温室气体“汇”的最新研究进展作了较为详尽的综述。针对目前温室气体汇研究中的主要前沿科学问题进行了深入分析:包括汇的定义、种类及方法学问题,土地利用变化和森林以及农业土壤汇的种类及计算中存在的一些问题,人类活动对自然生态系统源汇状况的影响等;对还估算各种温室气体源汇的不确定性作了分析总结;在列举了一些气候变化框架公约缔约国及发展中国家对《京都议定书》中引入温室气体“汇”的看法及态  相似文献   

16.
The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Fe, Mn and Zn) were determined in soils under different land use types in an urban environment in order to study the impact of land uses on the concentrations of metals in the soils. The mean concentration range of metals for all land use types were 42.1 to 410, 11.2 to 118.2, 4388.2 to 31891.1, 9.7 to 65.4, 0.1 to 1.8, 4.7 to 35.2, 2.0 to 16.8 and 77.9 to 881.7 mg/kg, for Mn, Pb, Fe, Cu, Cd, Cr, Ni and Zn, respectively. The computed multiple pollution index (MPI) indicated that 67 % of the examined sites had MPI values between 1 and 20 i.e. at the pollution range, while 33 % of sites had MPI values of zero which indicated that these sites were not polluted with the studied metals. Zinc had the highest impact on the multiple pollution index values. Three main principal components were identified from the principal component analysis which include (i) Cu, Zn, Pb, Cr and Ni originating from both industrial and agricultural sources, and as well as automobile exhausts; (ii) Fe and Mn which originated from both natural and anthropogenic sources; (iii) Cd which its anthropogenic origin is different from components I and II. This study provided information on the sources of metals in the urban environment and extent of contamination associated with each land use, which are useful in the ranking of contaminated sites, environmental quality management, environmental forensic studies and guidance for remediation/redevelopment of contaminated land.  相似文献   

17.
A persistent theme in land and agrarian studies is the appropriation of land and natural resources by mostly Western foreigners and the inequitable division of land and natural resources between Indigenous people and white settlers. It was this overt racial inequality in land ownership and the accompanying structures of oppression that led to the rise of liberation movements in Africa, South America and Asia. Most, if not all, land and agrarian reform programmes in the former colonies take the racial inequality in land as their point of departure. The same applies to the process of changing the inequalities in the use and ownership of natural resources such as wildlife, fisheries and forests. Whereas critical scholarship and social movements vehemently opposed the racialized nature of land dispossession, less attention has been paid to the persistence of racialized tenure systems. The silence on the racial character of land and natural resource tenure is rather surprising given that colonial tenure systems were based on race and racist grounds. This paper draws on examples from nature conservancies and communal land reform in southern Africa to argue that the dual land and natural resource tenure inherent from colonialism and apartheid remains intact in contemporary southern Africa. It also suggests that the democratic governments in the region and critical scholarship have failed to challenge the racialized character of land tenure. Instead, they continued to reinvent orthodox views of society and culture. Race seems to matter most in property regimes in the region in as far as it relates to equity rather than its initial categorization of people. The consequences of the persistence of the racialized tenure systems are that the success or failure of land and resource use and management reproduces racial explanations.  相似文献   

18.
Using enhanced land surface temperatures (LSTs) image retrieved from Landsat ETM+, this article shows that thermal information associated with faults have been detected. These anomalies may be provided by geothermal natural convection through faults and partially influence the ground surface thermal environment. The study area in southern segment of Longmen Mountains thrust belt of Western Sichuan Basin contains complex faults and folds with recent earthquake activity. In order to study the faults for future oil exploration, we use LST data retrieved from Landsat thermal infrared band to detect the thermal information associated with faults. The LSTs are enhanced by filtering out anthropogenic activity and influence land cover classes, and interpolating to contour map. The spatial patterns of the enhanced images revealed the spatial correspondence between the thermal information and the dip planes of faults when compared with the explanation profiles and geologic features obtained from the 3D-seismic geophysical data. The thermal-affected ranges calculated and the statistically significant of regression model also indicate the result that the thermal information located near the faults are consistent with the faults’ dip planes.  相似文献   

19.
从西部开发的历史经验与教训、土地利用的不合理现状等方面,阐述国家在实施西部地区大开发战略中加强土地利用控制的必要性及其重要意义。在此基础上,提出土地利用控制的目标与任务。分析了对西部经济发展、自然生态环境建设与保护等密切相关的耕地、林地和草地等在土地利用与控制中存在的问题,进而提出相应的土地利用控制措施与对策。  相似文献   

20.
The lateral transport of bicarbonate as dissolved inorganic carbon (DIC) to the oceans is an integral component of the global carbon budget and can represent the sequestration of CO2 from the atmosphere. Recently studies have implicated land use change, in particular agricultural development, as an accelerator of bicarbonate export. However, due to the co-variation of land use, bedrock and surficial geologies, and the relationship between bicarbonate export and climate, the impact of anthropogenic activities on DIC export remains an important research question. In order to examine the land use controls on DIC export from small temperate watersheds we sampled 19 streams draining catchments of varying land uses with similar bedrock and surficial geologies. In addition to an agricultural effect, there was a strong correlation between the percent of watershed in urban development and DIC concentrations and DIC yields. Urban watersheds exported 7.8 times more DIC than their nearby forested counterparts and 2.0 times more DIC than nearby agricultural catchments. Isotopic data suggest that excess DIC export from altered systems results from increased chemical weathering, enhanced CO2 production within urban green spaces, and as a result of organic matter loading from septic systems and leaky sewer lines. Furthermore, we found that nitrogen additions (e.g. fertilizers and manure) are aiding in the dissolution of lime, increasing the total export of DIC from agricultural watersheds. Calculated anthropogenic loading rates ranged from 0.43 to 0.86 mol C m− 2 yr− 1. These loading rates suggest that a significant portion of global DIC export might be attributable to human activities, although the impacts on CO2 sequestration are difficult to determine.  相似文献   

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