Glacier changes in the Sanjiangyuan Nature Reserve of China during 2000–2018

The glaciers in the Sanjiangyuan Nature Reserve of China (SNRC) are a significant water resource for the Yangtze,Yellow,and Mekong rivers.Based on Landsat Thematic Mapper(TM)/Operational Land Imager (OLI) images acquired in 2000,2010,and 2018,the outlines of glaciers in the SNRC were obtained by combining band ratio method with manual interpretation.There were 1714 glaciers in the SNRC in 2018,with an area of 2331.15±54.84 km2,an ice volume of 188.90±6.41 km3,and an average length of 1475.4±15 m.During 2000-2018,the corresponding values of glaciers decreased by 69,271.95±132.06 km2,18.59±8.83 km3,and 84.75±34 m,respectively.Glaciers in the Yangtze River source area witnessed the largest area loss (-154.45 km2),whereas glaciers in the Mekong River source area experienced the fastest area loss (-2.02％·a-1) and the maximum reduction of the average length (-125.82 m).Overall,the retreat of glaciers in the SNRC exhibited an accelerating trend.Especially,the loss rate of glacier area in the Yellow River source area in 2010-2018 was more than twice that in 2000-2010.The glacier change is primarily attributed to the significant rise in temperature during the ablation period.Some other factors including the size,orientation and terminus elevation of glaciers also contributed to the heterogeneity of glacier change.     

Spatio-temporal analysis of land-use conversion in the eastern coastal China during 1996–2005

Based on the acquaintance of the regional background of urban-rural transformational development and investigations on the spot,this paper discusses the holistic situation, dominant factors and mechanism of arable land loss and land for construction occupation in the coastal area of China over the last decade,with the aid of GIS technology.Conclusions of the research are summarized as follows：（1）the arable land had been continuously decreasing from 1996 to 2005,with a loss of 1,708,700 hm^2 and an average decrement of 170,900 hm^2 per year;（2）land for construction increased 1,373,700 hm^2 ,with an average increment of 153,200 hm^2 per year;（3）total area of encroachment on arable land for construction between 1996 and 2005 was 1,053,100 hm^2 ,accounting for 34.03%of the arable land loss in the same period,the percentages of which used for industrial land（INL）,transportation land（TRL）,rural construction land（RUL）and town construction land（TOL）are 45.03%,15.8%,15.47%and 11.5%,respectively;and（4）the fluctuation of the increase of construction land and encroachment on arable land in the area were deeply influenced by the nation＇s macroscopic land-use policies and development level of regional economy.The growth of population and advancement of technology promoted the rapid industrialization, construction of transportation infrastructures,rural urbanization and expansion of rural settlements in the eastern coastal area,and therefore were the primary driving forces of land-use conversion.     

Distribution and trend on consecutive days of severe weathers in China during 1959–2014

Based on daily surface climate data and weather phenomenon data, the spatial and temporal distribution and trend on the number of consecutive days of severe weathers were analyzed in China during 1959–2014. The results indicate that the number of consecutive days for hot weathers increased at a rate of 0.1 day per decade in China as a whole, while that for cold weathers, snowfall weathers, thunderstorm weathers and foggy weathers showed significant decreasing trends at rates of 1.4, 0.3, 0.4 and 0.4 day per decade, respectively. Spatially, there were more consecutive hot days and rainstorm days in southeastern China, and more consecutive cold days and snowfall days in northeastern China and western China. Consecutive thunderstorm days were more in southern China and southwestern China, and consecutive foggy days were more in some mountain stations. Over the past 56 years, annual number of consecutive cold days decreased mainly in most parts of western China and eastern China. Consecutive thunderstorm days decreased in most parts of China. The trend of consecutive hot days, snowfall days and foggy days was not significant in most parts of China, and that of consecutive rainstorm days was not significant in almost the entire China.     

Effects of rural–urban migration on vegetation greenness in fragile areas: A case study of Inner Mongolia in China

Different government departments and researchers have paid considerable attention at various levels to improving the eco-environment in ecologically fragile areas. Over the past decade, large numbers of people have emigrated from rural areas as a result of the rapid urbanization in Chinese society. The question then remains: to what extent does this migration affect the regional vegetation greenness in the areas that people have moved from? Based on normalized difference vegetation index (NDVI) data with a resolution of 1 km, as well as meteorological data and socio-economic data from 2000 to 2010 in Inner Mongolia, the spatio-temporal variation of vegetation greenness in the study area was analyzed via trend analysis and significance test methods. The contributions of human activities and natural factors to the variation of vegetation conditions during this period were also quantitatively tested and verified, using a multi-regression analysis method. We found that: (1) the vegetation greenness of the study area increased by 10.1% during 2000-2010. More than 28% of the vegetation greenness increased significantly, and only about 2% decreased evidently during the study period. (2) The area with significant degradation showed a banded distribution at the northern edge of the agro-pastoral ecotone in central Inner Mongolia. This indicates that the eco-environment is still fragile in this area, which should be paid close attention. The area where vegetation greenness significantly improved showed a concentrated distribution in the southeast and west of Inner Mongolia. (3) The effect of agricultural labor on vegetation greenness exceeded those due to natural factors (i.e. precipitation and temperature). The emigration of agricultural labor improved the regional vegetation greenness significantly.     

Human–environment dynamics during the Iron Age in the Lofoten Islands,Norway

Integrated archaeological and paleoenvironmental investigations provide long-term perspectives on human–environment interactions. In the North Atlantic region, early human settlements were established in marginal agricultural environments and were susceptible to various environmental stressors. The Lofoten Islands have had an important role in the history of this region, particularly during the Iron Age, when Lofoten developed from pioneering agricultural settlements to a prominent node of power and trade under Viking chieftains. Iron Age developments in Lofoten were concurrent with significant natural environmental changes, including variations in climate and sea level. However, there has not been a comprehensive investigation of their influence on early settlements. The purpose of the study is to review Iron Age cultural developments in Lofoten using published archaeological data and paleoenvironmental records of past climate and sea-level change, and to present specific examples of the intersection of early human development and natural environmental changes. The findings show that climate changes probably influenced agricultural phases and that relative sea-level variations had important impacts on maritime developments. In conclusion, the findings demonstrate that human–environment interactions were significant factors in Lofoten’s history and the authors suggest specific areas for future research.     

Uncertainty analysis of space–time prisms based on the moment-design method

Space–time prism (STP) is an important concept for the modeling of object movements in space and time. An STP can be conceptualized as the result of the potential path of a moving object revolving around in the three-dimensional space. Though the concept has found applications in time geography, research on the analysis and propagation of uncertainty in STPs, particularly under high degree of nonlinearity, is scanty. Based on the efficiency and effectiveness of the moment-design (M-D) method, this paper proposes an approach to deal with nonlinear error propagation problems in the potential path areas (PPAs) of STPs and their intersections. Propagation of errors to the PPA and its boundary, and to the intersection of two PPAs is investigated. Performance of the proposed method is evaluated via a series of experimental studies. In comparison with the Monte Carlo method and the implicit function method, simulation results show the advantages of the M-D method in the analysis of error propagation in STPs.     

Spatio-temporal variation prediction on Cd content in the rice grains from Northern Zhejiang Plain during 2014–2019 based on high-precision soil geochemical data

Journal of Geographical Sciences - In recent years, Cadmium (Cd) pollution has been found in many soil geochemical surveys in Northern Zhejiang Plain, a crucial rice production area in East China,...     

Spatiotemporal changes in frequency and intensity of high-temperature events in China during 1961–2014

In this study, we explored spatial patterns and the temporal trends in high-temperature events (HTEs) for the mainland of China during 1961–2014 based on a daily- maximum surface-air-temperature dataset of 494 stations and nonparametric trend detection methods. With three thresholds of 35°C (HTE35), 37°C (HTE37), and 40°C (HTE40), HTEs occurred in 82%, 71%, and 37% of the surveyed stations and showed an overall increasing trend in both frequency and intensity during 1961–2014. In northern and southeastern China, HTEs showed a significant increasing trend in both frequency and intensity, whilst a decreasing trend for both was observed in central China. Despite such regional heterogeneity, HTEs overwhelmingly presented three-phase characteristics in all three representative regions and throughout China; the phases are 1961–1980, 1980–1990, and 1990–2014. Both frequency and intensity of HTEs have strongly increased during 1990–2014 at 54.86%, 48.38%, and 23.28% of the investigated stations for HTE35, HTE37 and HTE40, respectively. These findings implied that HTEs adaptation should be paid further attention in the future over China because the wide spread distribution of HTEs and their increasing trends in both frequency and intensity during recent decades might pose challenges to the sustainability of human society and the ecosystem.     

The shape of Fraught – urban – rural – the nation-state: tensions and dynamics

I argue that the tension between cities and nation states go through the countryside, or rural areas, at least in the U.S. Further, cities are decidedly constrained in their abilities to effectuate many of the changes associated with them: addressing climate change, economic inequality and more. What is missing is the way in which rural alienation from economic prosperity plays out politically.     

Distribution and trend in the thermal growing season in China during 1961–2015

Abstract

Based on daily mean temperature at 1863 meteorological stations in China, the trend in the thermal growing season was investigated and time-evolving probability distributions of temperature were examined. Results showed that during 1961–2015, the growing season was extended at rates of 1.5–5.0 days decade^?1 in Northeast China, North China, Northwest China, and western and central parts of Southwest China. This change was ascribed to an earlier start of the growing season at rates of 1.5–3.0 days decade^?1 in North China, the northern and western parts of Northeast China, and the northeastern part of Northwest China, and a later end at rates of 0.5–2.5 days decade^?1 in Northwest China, the western and northern parts of Southwest China, and the northwest of North China. The earlier start of the growing season was in accordance with the rapid warming of lower portions of the spring temperature distribution in Northeast China, North China, and Northwest China. The later end of the growing season corresponded to rapid warming in the lower percentiles of autumn temperature distribution in Northwest China. The growing season is more sensitive to warming of lower percentiles of temperature distribution than other portions.     

Lake evolution and its implication for environmental changes in China during 1950–2000

Lakes in China have undergone considerable environmental changes during the past 50 years, e.g. lake level, water area changes, as did in the past several thousands years. The enhanced human activities, such as land reclamation, application of chemical fertilizer, land use and cover, irrigation and industrialization in the catchment etc., have played an important role on the recent decades＇ changes of these lakes, although constrained to a great extent by the natural impact. Comparative study on variations of lake volume （water level, depth and area） in the eastern and western lake regions of China during 1950-2000 indicated that, lake volume in the eastern region had approximately undergone a two-stage change, i.e. a dramatic decrease from the 1950s to 1970s, and a continuous increase between the 1980s and 1990s; while, in the western region, lake volume had been decreasing nearly all the time. Further studies on some typical lakes concluded that, climatic change was a primary factor for the variations of lake volume during the past 50 years, although human activities showed important effect.     

The Spatial–Temporal Hierarchy of Inequality in Urban China: A Prefectural City–Level Study

Inequality has been the subject of intense debates in China, but inequality across cities remains less studied. This article investigates economic inequality based on prefectural-level cities during the period from 1990 to 2010. Statistical analyses indicate that interregional inequality among cities has increased, which is mostly attributable to widening intraregional inequality, especially within the western region. The high gross domestic product (GDP) per capita clusters emerged in the Pearl River Delta in the 1990s, spread to the Yangtze River Delta in the 2000s, and then reached north China in the 2010s. In contrast, the number of low GDP per capita clusters significantly increased in the central and western regions in the 2010s. In addition, the significance of national development zones and foreign direct investment indicates the greatest effect of globalization on the increasing intercity inequality. Decentralization also contributes to the intercity inequality of China. We suggest that in addition to national programs aimed at reducing the inequality between the eastern region and the rest of China, efforts are needed to reduce inequality within each region through provincial and local government policies, especially in western China. Key Words: China, cluster, decentralization, globalization, regional inequality, urban inequality.     

A Note on Tree Deaths during the Current (2001–?) Drought in South-eastern Australia

Tree deaths over large areas during droughts are uncommon. In the semi-arid zone of New South Wales (NSW) such events were last reported during the prolonged droughts of 1895–1903 and 1939–45, though whether caused solely by drought is open to question. Anecdotal and quantitative evidence during the current prolonged drought (2001–?) in NSW's sub-humid zone (where deaths are localised) and semi-arid zone (where deaths are more extensive) suggest that climatic conditions are comparable to, and perhaps more severe than, those of the earlier prolonged droughts. It is suggested that lack of access to deep soil moisture due to inherent shallow rooting, or due to site conditions, is the most likely cause; and that this may be associated with higher than optimal tree densities in cohorts of trees that arose from previous regeneration events during periods of well above average rainfall. A more thorough examination of the extent and severity of this event is warranted.     

Spatial-temporal variations in cold surge events in northern China during the period 1960–2016

Journal of Geographical Sciences - Among the most devastating extreme weather events, cold surge (CS) events frequently impact northern China. It has been reported that extreme weather events will...     

Change and continuity of income divide in the American Southeast: A metropolitan scale analyses, 2000–2014

Changing racial/ethnic diversity along with economic growth have also drawn renewed public attention to growing income inequality and lack of economic well-being in the American society. This paper investigates one element of contemporary inequality – the income divide between the richest and the poorest population groups in the metropolises of the U.S. Southeast. This paper examines income divide across southern U.S. metropolises in 2000 and 2014, their change during 2000–2014, their variation across major races/ethnicities, and their relationships with important metropolitan characteristics such as diversity, intermixing, socio-economic status and built-environment attributes. Cartographic, ranking/matrix, and correlations analyses suggest that the largest, most diverse, most segregated, and those with a greater presence of better educated are the most income divided metropolises, whereas the small-to-mid-sized metropolises, with lesser educated population are less divided. The income divide has increased during 2000–2014 in a majority of these metropolises, and for all races/ethnicities, even though Whites and Asians are relatively better-off compared to overall population whereas Blacks and Hispanics lag behind.     

Remote sensing assessment of the ecological benefits provided by national key ecological projects in China during 2000–2019

We propose a theoretical framework for assessing the ecological benefits provided by key national ecological projects in China over the past 20 years. A dataset consisting of six primary indicators and nine secondary indicators of ecosystem structure, ecosystem quality,and ecosystem services for 2000–2019 was generated using ground survey and remote sensing data. Ecological benefits were quantitatively evaluated following the implementation of these projects in China. Areas with medium, relative...     

Correlation analysis between vegetation coverage and climate drought conditions in North China during 2001–2013

Climate change is one of the most important factors that affect vegetation distribution in North China. Among all climatic factors, drought is considered to have the most significant effect on the environment. Based on previous studies, the climate drought index can be used to assess the evolutionary trend of the ecological environment under various arid climatic conditions. It is necessary for us to further explore the relationship between vegetation coverage (index) and climate drought conditions. Therefore, in this study, based on MODIS-NDVI products and meteorological observation data, the Palmer Drought Severity Index (PDSI) and vegetation coverage in North China were first calculated. Then, the interannual variations of PDSI and vegetation coverage during 2001–2013 were analyzed using a Theil-Sen slope estimator. Finally, an ecoregion perspective of the correlation between them was discussed. The experimental results demonstrated that the PDSI index and vegetation coverage value varied over different ecoregions. During the period 2001–2013, vegetation coverage increased in the southern and northern mountains of North China, while it showed a decreasing trend in the Beijing-Tianjin-Tangshan City Circle area and suburban agricultural zone located in Hebei Province and Henan Province). Over 13 years, the climate of the northeastern part of North China became more humid, while in the southern part of North China, it tended to be dry. According to the correlation analysis results, 73.37% of North China showed a positive correlation between the vegetation coverage and climate drought index. A negative correlation was observed mainly in urban and suburban areas of Beijing, Tianjin, Hebei Province, and Henan Province. In most parts of North China, drought conditions in summer and autumn had a strong influence on vegetation coverage.     

Modeling the spatio-temporal changes in land uses and its impacts on ecosystem services in Northeast China over 2000–2050

Land use and its dynamics have attracted considerable scientific attention for their significant ecological and socioeconomic implications. Many studies have investigated the past changes in land use, but efforts exploring the potential changes in land use and implications under future scenarios are still lacking. Here we simulate the future land use changes and their impacts on ecosystem services in Northeast China (NEC) over the period of 2000–2050 using the CLUE–S (Conversion of Land Use and its Effects at Small regional extent) model under the scenarios of ecological security (ESS), food security (FSS) and comprehensive development (CDS). The model was validated against remote sensing data in 2005. Overall, the accuracy of the CLUE–S model was evaluated at 82.5%. Obtained results show that future cropland changes mainly occur in the Songnen Plain and the Liaohe Plain, forest and grassland changes are concentrated in the southern Lesser Khingan Mountains and the western Changbai Mountains, while the Sanjiang Plain will witness major changes of the wetlands. Our results also show that even though CDS is defined based on the goals of the regional development plan, the ecological service value (ESV) under CDS is RMB 2656.18 billion in 2050. The ESV of CDS is lower compared with the other scenarios. Thus, CDS is not an optimum scenario for eco-environmental protection, especially for the wetlands, which should be given higher priority for future development. The issue of coordination is also critical in future development. The results can help to assist structural adjustments for agriculture and to guide policy interventions in NEC.     

Vulnerability of natural ecosystem in China under regional climate scenarios：An analysis based on eco-geographical regions

Assessment of vulnerability for natural ecosystem to climate change is a hot topic in climate change and ecology,and will support adapting and mitigating climate change. In this study,LPJ model modified according to features of China's natural ecosystems was employed to simulate ecosystem dynamics under A2,B2 and A1B scenarios. Vulnerability of natural ecosystem to climate change was assessed according to the vulnerability assessment model. Based on eco-geographical regions,vulnerability of natural ecosystem to climate change was analyzed. Results suggest that vulnerability for China's natural ecosystems would strengthen in the east and weaken in the west,but the pattern of ecosystem vulnerability would not be altered by climate change,which rises from southeast to northeast gradually. Increase in ecosystem vulnerable degree would mainly concentrate in temperate humid/sub-humid region and warm temperate humid/sub-humid region. Decrease in ecosystem vulnerable degree may emerge in northwestern arid region and Qinghai-Tibet Plateau region. In the near-term scale,natural ecosystem in China would be slightly affected by climate change. However,in mid-term and long-term scales,there would be severely adverse effect,particularly in the east with better water and thermal condition.     

NDVI changes in China between 1989 and 1999 using change vector analysis based on time series data

1 Introduction The land surface has considerable control on the planet抯 energy balance, biogeochemical cycles and hydrologic cycle, which in turn significantly influences the climate system. Therefore, the global environmental change community has paid great attention to the land use/cover change (LUCC). Many researchers have focused on the land cover classification and change by using remotely sensed data. Changes in land-cover are driven by four categories of causes[1]: (1) long-term nat…