Ecological environmental quality evaluation and driving factor analysis of the Lijiang River Basin,based on Google Earth Engine

For regional ecological management,it is important to evaluate the quality of ecosystems and analyze the underlying causes of ecological changes.Using the Google Earth Engine(GEE)platform,the remote sensing ecological index(RSEI)was calculated for the Lijiang River Basin in Guangxi Zhuang Autonomous Region for 1991,2001,2011,and 2021.Spatial autocorrelation analysis was employed to investigate spatiotemporal variations in the ecological environmental quality of the Lijiang River Basin.Furthermore,geographic detectors were used to quantitatively analyze influencing factors and their interaction effects on ecological environmental quality.The results verified that:1)From 1991 to 2021,the ecological environmental quality of the Lijiang River Basin demonstrated significant improvement.The area with good and excellent ecological environmental quality in proportion increased by 19.69%(3406.57 km^(2)),while the area with fair and poor ecological environmental quality in proportion decreased by 10.76%(1860.36 km^(2)).2)Spatially,the ecological environmental quality of the Lijiang River Basin exhibited a pattern of low quality in the central region and high quality in the periphery.Specifically,poor ecological environmental quality characterized the Guilin urban area,Pingle County,and Lingchuan County.3)From 1991 to 2021,a significant positive spatial correlation was observed in ecological environmental quality of the Lijiang River Basin.Areas with high-high agglomeration were predominantly forests and grasslands,indicating good ecological environmental quality,whereas areas with low-low agglomeration were dominated by cultivated land and construction land,indicating poor ecological environmental quality.4)Annual average precipitation and temperature exerted the most significant influence on the ecological environmental quality of the basin,and their interactions with other factors had the great influence.This study aimed to enhance understanding of the evolution of the ecological environment in the Lijiang River Basin of Guangxi Zhuang Autonomous Region and provide scientific guidance for decision-making and management related to ecology in the region.

Quantifying the response of surface urban heat island to urbanization using the annual temperature cycle model

Urban heat island(UHI),driving by urbanization,plays an important role in urban sustainability under climate change.However,the quantification of UHI’s response to urbanization is still challenging due to the lack of robust and continuous temperature and urbanization datasets and reliable quantification methods.This study proposed a framework to quantify the response of surface UHI(SUHI)to urban expansion using the annual temperate cycle model.We built a continuous annual SUHI series at the buffer level from 2003 to 2018 in the Jing-Jin-Ji region of China using MODIS land surface temperature and imperviousness derived from Landsat.We then investigated the spatiotemporal dynamic of SUHI under urban expansion and examined the underlying mechanism.Spatially,the largest SUHI interannual variations occurred in suburban areas compared to the urban center and rural areas.Temporally,the increase in SUHI under urban expansion was more significant in daytime compare to nighttime.We found that the seasonal variation of SUHI was largely affected by the seasonal variations of vegetation in rural areas and the interannual variation was mainly attributed to urban expansion in urban areas.Additionally,urban greening led to the decrease in summer daytime SHUI in central urban areas.These findings deepen the understanding of the long-term spatiotemporal dynamic of UHI and the quantitative relationship between UHI and urban expansion,providing a scientific basis for prediction and mitigation of UHI.

Spatio-temporal Characteristics of Disturbance of Land Use Change on Major Ecosystem Function Zones in China

In recent years, because of increasing human activities, ecosystems have been substantially disturbed and their service functions have been greatly compromised. Based on the effect of land use changes on the major ecosystem services, we estimated the ecosystem comprehensive anthropogenic disturbance index(ECADI) and analyzed the spatio-temporal characteristics of changes in the ECADI in China from 1990 to 2010. The average ECADI of the major ecosystem function zones in China in 2010 is approximately 0.382. The ECADI of Northeast China and North China is slightly higher than that of Northwest China and Southwest China. Most zones have slight changes in the ECADI. The average increases of ECADI in the major ecosystem function zones in China from 1990 to 2000 and from 2000 to 2010 are 0.0024 and 0.0002, respectively. The increase is mainly due to reclamation and urbanization, whereas the decrease is due to the implementation of ecosystem protection policies. During the last 20 years, the ECADI of water resources conservation zones increased first, and then stopped. The ECADI of soil conservation zones increased first, and then declined. The ECADI of sandstorm prevention zones, biodiversity conservation zones and flooding mitigation zones increased continuously. Our results may provide proposals to the government regarding land use planning and ecosystem protection plans in the major ecosystem zones. The major ecosystem function zones in the western part of China have been protected effectively. However, the major ecosystem function zones in the eastern part of China require more protection in the future.

Influences of drip and flood irrigation on soil carbon dioxide emission and soil carbon sequestration of maize cropland in the North China Plain

The need is pressing to investigate soil CO2 （carbon dioxide） emissions and soil organic carbon dynamics under water-saving irrigation practices in agricultural systems for exploring the potentials of soil carbon sequestration. A field experiment was conducted to compare the influences of drip irrigation （DI） and flood irrigation （FI） on soil organic carbon dynamics and the spatial and temporal variations in CO2 emissions during the summer maize growing season in the North China Plain using the static closed chamber method. The mean CO2 efflux over the growing season was larger under DI than that under FI. The cumulative CO2 emissions at the field scale were 1959.10 and 1759.12 g/m2 under DI and FI, respectively. The cumulative CO2 emission on plant rows （OR） was larger than that between plant rows （BR） under FI, and the cumulative CO2 emission on the irrigation pipes （OP） was larger than that between irrigation pipes （BP） under DI. The cumulative CO2 emissions of OP, BP and bare area （BA） under DI were larger than those of OR, BR and BA under FI, respectively. Additionally, DI promoted root respiration more effectively than FI did. The average proportion of root respiration contributing to the soil CO2 emissions of OP under DI was larger than that of OR under FI. A general conclusion drawn from this study is that soil CO2 emission was significantly influenced by the soil water content, soil temperature and air temperature under both DI and FI. Larger concentrations of dissolved organic carbon （DOC）, microbial biomass carbon （MBC） and total organic carbon （TOC） were observed under FI than those under DI. The observed high concentrations （DOC, MBC, and TOC） under FI might be resulted from the irrigation-associated soil saturation that in turn inhibited microbial activity and lowered decomposition rate of soil organic matter. However, DI increased the soil organic matter quality （the ratio of MBC to TOC） at the depth of 10-20 cm compared with FI. Our results suggest that the transformation from conventional FI to integrated DI can increase the CO2 emissions and DI needs to be combined with other management practices to reduce the CO2 emissions from summer maize fields in the North China Plain.

Land use and land cover change within the Koshi River Basin of the central Himalayas since 1990

Land change is a cause and consequence of global environmental change.Land use and land cover have changed considerably due to increasing human activities and climate change,which has become the core issue of major international research projects.This study interprets land use and land cover status and the changes within the Koshi River Basin(KRB)using Landsat remote sensing(RS)image data,and employs logistic regression model to analyze the influence of natural and socioeconomic driving forces on major land cover changes.The results showed that the areas of built-up land,bare land and forest in KRB increased from 1990 to 2015,including the largest increases in forest and the highest growth rate in construction land.Areas of glacier,grassland,sparse vegetation,shrub land,cropland,and wetland all decreased over the study period.From the perspective of driving analysis,the role of human activities in land use and land cover change is significant than climate factors.Cropland expansion is the reclamation of cropland by farmers,mainly from early deforestation.However,labor force separation,geological disasters and drought are the main factors of cropland shrinkage.The increase of forest area in India and Nepal was attributed to the government’s forest protection policies,such as Nepal’s community forestry has achieved remarkable results.The expansion and contraction of grassland were both dominated by climatic factors.The probability of grassland expansion increases with temperature and precipitation,while the probability of grassland contraction decreases with temperature and precipitation.

Spatio-temporal Differentiation of Residential Land for Coastal Town: A Case Study of Dalian Jinshitan

Based on SPOT5 satellite remote sensing images and land use data in five time phases covering the period 1988–2012, the distribution characteristics, spatial differentiation processes, and driving mechanisms affecting the residential land of the Jinshitan Tourist Resort were studied. The work included a combination of GIS technology, adoption of the differentiation index D, and the multi-group differentiation-measure model D(m). The results provided a basis for the following conclusions: 1) From 1988 to 2012, the degree of differentiation of the rural residential land first decreased, and then increased. The general residential, commercial residential and garden-house land-types all showed declining trends, of which the garden-house type presented the most intense volatility. 2) The overall background of the traditional residential land type was gradually replaced by a new residential land type, and the total area of residential land increased year by year, significantly improving the overall residential conditions. The areas of the new residential land type showed growth, and were increasingly widely distributed in the coastal tourist resorts, transportation corridors, and scenic areas. 3) Government policy, social differentiation, market mechanisms, and individual choices(along with other factors) were mutually promoted, although still restrained. However, all of these factors interacted to constrain the developmental direction and the processes affecting tourism real estate in the Dalian Jinshitan Tourist Resort.

Incorporating Exercise Efficiency to Evaluate the Accessibility and Capacity of Medical Resources in Tibet, China

Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China.Through introducing exercise efficiency, this study explores the accessibility of township residence to county-ship medical resources in Tibet using weighted mean travel time(WMT), and evaluates the medical capacity accordingly.The results show that: 1) the average travel time of township residence to county-level hospital is around2 h by motor vehicle in Tibet.More than half of the population can not reach the county-ship hospital within 1 h, 33.24% of the population can not reach within 2 h, and 3.75% of the population can not reach within 6 h.2) When considering the catchment of the medical resources and the population size, the WMT of the county-ship medical resources ranges from 0.25 h to 10.92 h.3) After adjusted by travel time and exercise efficiency, the county-ship medical capacity became more unequal, with 38 out of 74 counties could not meet the national guideline of 1.8 medical beds per 1000.4) In total, there are 17 counties with good WMT and sufficient medical resources,while 13 counties having very high WMT and low capacity of medical resources in Tibet.In the end, suggestions on medical resources relocation and to improve the capacity are provided.This study provides a method to incorporate exercise efficiency to access the accessibility and evaluate medical capacity that can be applied in high altitude ranges.

Study of the intensity and driving factors of land use/cover change in the Yarlung Zangbo River, Nyang Qu River, and Lhasa River region, Qinghai-Tibet Plateau of China

Land use/land cover(LULC) is an important part of exploring the interaction between natural environment and human activities and achieving regional sustainable development. Based on the data of LULC types(cropland, forest land, grassland, built-up land, and unused land) from 1990 to 2015, we analysed the intensity and driving factors of land use/cover change(LUCC) in the Yarlung Zangbo River,Nyang Qu River, and Lhasa River(YNL) region, Qinghai-Tibet Plateau of China, using intensity analysis method, cross-linking table method, and spatial econometric model. The results showed that LUCC in the YNL region was nonstationary from 1990 to 2015, showing a change pattern with "fast-slow-fast" and "U-shaped". Built-up land showed a steady increase pattern, while cropland showed a steady decrease pattern. The gain of built-up land mainly came from the loss of cropland. The transition pattern of LUCC in the YNL region was relatively single and stable during 1990–2015. The transition pattern from cropland and forest land to built-up land was a systematic change process of tendency and the transition pattern from grassland and unused land to cropland was a systematic change process of avoidance. The transition process of LUCC was the result of the combined effect of natural environment and social economic development in the YNL region. This study reveals the impact of ecological environment problems caused by human activities on the land resource system and provides scientific support for the study of ecological environment change and sustainable development of the Qinghai-Tibet Plateau.

Characteristics of Temperature Change in China over the Last 2000 years and Spatial Patterns of Dryness/Wetness during Cold and Warm Periods

This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation in China has exhibited significant 50–70-yr, 100–120-yr, and 200–250-yr cycles. Results also show that the amplitudes of decadal and centennial temperature variation were 1.3℃ and 0.7℃, respectively, with the latter significantly correlated with long-term changes in solar radiation, especially cold periods, which correspond approximately to sunspot minima. The most rapid warming in China occurred over AD 1870–2000, at a rate of 0.56°± 0.42℃（100 yr）^（-1）; however, temperatures recorded in the 20 th century may not be unprecedented for the last 2000 years, as data show records for the periods AD 981–1100 and AD1201–70 are comparable to the present. The ensemble means of dryness/wetness spatial patterns in eastern China across all centennial warm periods illustrate a tripole pattern： dry south of 25°N, wet from 25°–30°N, and dry to the north of 30°N. However, for all centennial cold periods, this spatial pattern also exhibits a meridional distribution. The increase in precipitation over the monsoonal regions of China associated with the 20 th century warming can primarily be attributed to a mega El Nino–Southern Oscillation and the Atlantic Multidecadal Oscillation. In addition, a significant association between increasing numbers of locusts and dry/cold conditions is found in eastern China. Plague intensity also generally increases in concert with wetness in northern China, while more precipitation is likely to have a negative effect in southern China.

Impacts of Land-use and Land-cover Changes on River Runoff in Yellow River Basin for Period of 1956–2012

River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-use and land-cover change(LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge(not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956–2012, especially from the mid-1980 s to the end-1990 s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980 s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology.

Calibration and validation of SiBcrop Model for simulating LAI and surface heat fluxes of winter wheat in the North China Plain

The accurate representation of surface characteristic is an important process to simulate surface energy and water flux in land-atmosphere boundary layer.Coupling crop growth model in land surface model is an important method to accurately express the surface characteristics and biophysical processes in farmland.However,the previous work mainly focused on crops in single cropping system,less work was done in multiple cropping systems.This article described how to modify the sub-model in the SiBcrop to realize the accuracy simulation of leaf area index(LAI),latent heat flux(LHF)and sensible heat flux(SHF)of winter wheat growing in double cropping system in the North China Plain(NCP).The seeding date of winter wheat was firstly reset according to the actual growing environment in the NCP.The phenophases,LAI and heat fluxes in 2004–2006 at Yucheng Station,Shandong Province,China were used to calibrate the model.The validations of LHF and SHF were based on the measurements at Yucheng Station in 2007–2010 and at Guantao Station,Hebei Province,China in 2009–2010.The results showed the significant accuracy of the calibrated model in simulating these variables,with which the R2,root mean square error(RMSE)and index of agreement(IOA)between simulated and observed variables were obviously improved than the original code.The sensitivities of the above variables to seeding date were also displayed to further explain the simulation error of the SiBcrop Model.Overall,the research results indicated the modified SiBcrop Model can be applied to simulate the growth and flux process of winter wheat growing in double cropping system in the NCP.

Review of studies on land use and land cover change in Nepal

Land use and land cover(LULC) in Nepal has undergone constant change over the past few decades due to major changes caused by anthropogenic and natural factors and their impacts on the national and regional environment and climate.This comprehensive review of past and present studies of land use and land cover change(LUCC) in Nepal concentrates on cropland, grassland, forest, snow/glacier cover and urban areas. While most small area studies have gathered data from different sources and research over a short period, across large areas most historical studies have been based on aerial photographs such as the Land Resource Mapping Project in 1986. The recent trend in studies in Nepal is to focus on new concepts and techniques to analyze LULC status on the basis of satellite imagery, with the help of geographic information system and remote sensing tools. Studies based on historical documents, and historical and recent spatial data on LULC, have clearly shown an increase in cropland areas in Nepal,and present results indicating different rates and magnitudes. A decrease in forest and snow/glacier coverage is reported in most studies. Little information is available on grassland and urban areas from past research. The unprecedented rate of urbanization in Nepal has led to significant urban land changes over the past 30 years. Meanwhile, long term historical LUCC research in Nepal is required for extensive work on spatially explicit reconstructions on the basis of historical and primary data collection, including LULC archives and drivers for future change.

Spatial and temporal change patterns of freeze-thaw erosion in the three-river source region under the stress of climate warming

The three-river source region(TRSR), located in the Qinghai-Tibet Plateau in China, suffers from serious freeze-thaw(FT) erosion in China. Considering the unique eco-environment and the driving factors of the FT process in the TRSR, we introduce the driving force factors of FT erosion(rainfall erosivity and wind field intensity during FT period) and precipitation during the FT period(indicating the phase-changed water content). The objective was to establish an improved evaluation method of FT erosion in the TRSR. The method has good applicability in the study region with an overall precision of 92%. The spatial and temporal changes of FT erosion from 2000 to 2015 are analyzed. Results show that FT erosion is widely distributed in the TRSR, with slight and mild erosion being the most widely distributed, followed by moderate erosion. Among the three sub-regions, the source region of the Yellow River has the slightest erosion intensity, whereas the erosion intensity of the source region of Yangtze River is the most severe. A slight improvement can be observed in the condition of FTerosion over the whole study region from 2000 to 2015. Vegetation coverage is the dominant factor affecting the intensity of FT erosion in the zones with sparse vegetation or bare land, whereas the climate factors play an important role in high vegetation coverage area. Slopes>28° also have a significant effect on the intensity of FT erosion in the zones. The results can provide a scientific basis for the prevention and management of the soil FT erosion in the TRSR.

A Review on Diagnostic Phytoliths for the Application in Paleovegetation Reconstruction and Environmental Archaeology in East Asia

Phytoliths are extensively utilized as an archaeobotanical indicator in paleovegetation reconstruction and environmental archaeology. Over the past two decades, numerous phytolith morphotypes, particularly those exhibiting diagnostic morphological features and over representative of source plants at the genus and species levels, were discovered and reported. These advancements have significantly contributed to phytolith-based vegetation reconstruction on different timescales, enhanced our understanding of prehistoric plant utilization, and elucidated cultivation and domestication processes of key crops in ancient agriculture. However, there are still inconsistencies and misunderstandings regarding the morphological characteristics of diagnostic phytoliths in various plant groups. This review highlighted the standardization in the classification and description of phytolith morphotypes, and summarized the advancements in phytolith morphology research over the past two decades. Morphological illustrations of diagnostic phytoliths from various plant groups, particularly key crops and their relatives from dryland and rice agriculture in East Asia, were presented as references for phytolith identification and application. Finally, this review proposes future directions for phytolith morphological studies, emphasizing the comprehensive consideration of anatomical structure and morphometric parameters, as well as the need for extensive research on modern plant phytoliths and control experiments on phytolith growth.

Mapping cropping patterns in the North China Plain over the past 300 years and an analysis of the drivers of change

It is essential to map the cropping patterns when investigating the mechanisms and impacts of climate change.However,the long-term evolution of cropping patterns remains poorly understood.This study collected hundreds of records of cropping intensity and crop combinations from local gazetteers and other relevant articles for the North China Plain(NCP)over the past 300 years.Then,we analyzed the evolutionary characteristics and drivers in terms of climate change and advances in agricultural technology.From the Qing Dynasty to the 1950s,one harvest per year(1H1Y)was the dominant pattern in the northern NCP,and three harvests in two years(3H2Y)was the dominant pattern in Henan and Shandong provinces.The 1H1Y crops were cereals and sorghum.The 3H2Y crop combinations were spring maize,winter wheat,and beans.In the 1960s and 1970s,the cropping intensity in much of the NCP was two harvests per year(2H1Y)or a mix of the 2H1Y and 3H2Y patterns.In the 1980s,the cropping intensity in the NCP was dominated by 2H1Y.Since the 1960s,the 2H1Y crop compositions have been winter wheat-summer maize in Shandong,Henan,and Hebei provinces,while winter wheat-rice dominated north of the Huaihe River.The 3H2Y summer crop changed from beans to maize/cereals over time.Climate warming was not the dominant factor driving the evolution of cropping intensity in the NCP.Advances in agricultural production conditions and reforms in production relations have promoted the rapid development of multiple cropping since the 1950s.

Characteristics and hazards of different snow avalanche types in a continental snow climate region in the Central Tianshan Mountains

Snow avalanches are a common natural hazard in many countries with seasonally snow-covered mountains.The avalanche hazard varies with snow avalanche type in different snow climate regions and at different times.The ability to understand the characteristics of avalanche activity and hazards of different snow avalanche types is a prerequisite for improving avalanche disaster management in the mid-altitude region of the Central Tianshan Mountains.In this study,we collected data related to avalanche,snowpack,and meteorology during four snow seasons(from 2015 to 2019),and analysed the characteristics and hazards of different types of avalanches.The snow climate of the mid-altitude region of the Central Tianshan Mountains was examined using a snow climate classification scheme,and the results showed that the mountain range has a continental snow climate.To quantify the hazards of different types of avalanches and describe their situation over time in the continental snow climate region,this study used the avalanche hazard degree to assess the hazards of four types of avalanches,i.e.,full-depth dry snow avalanches,full-depth wet snow avalanches,surface-layer dry snow avalanches,and surface-layer wet snow avalanches.The results indicated that surface-layer dry snow avalanches were characterized by large sizes and high release frequencies,which made them having the highest avalanche hazard degree in the Central Tianshan Mountains with a continental snow climate.The overall avalanche hazard showed a single peak pattern over time during the snow season,and the greatest hazard occurred in the second half of February when the snowpack was deep and the temperature increased.This study can help the disaster and emergency management departments rationally arrange avalanche relief resources and develop avalanche prevention strategies.

Crop production changes and the impact of Grain for Green program in the Loess Plateau of China

Since the Grain for Green(GFG)program was implemented in 1999,most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland.To understand its impact on the food production,this study analyzed the spatiotemporal changes of food crop production(FCP)in the plateau and quantified the contribution of sown area and yield changes to the total FCP during 1998–2014 using factor decomposition models,and then discussed the impact of GFG program on the FCP based on literature data.With the implementation of GFG program,total sown area in the Loess Plateau quickly deceased by 17.3%from 1998 to 2003,and then gradually restored to 1.03×107 hm2 in 2010.Thereafter,it slightly decreased to 1.02×107 hm2(94.6%of the area in 1998)in 2014.By contrast,total FCP generally showed an apparent growth trend,averagely increased by 1.71%per year in the whole plateau during 1998–2014.This increase was jointly contributed by the improved yield of individual crops,and the adjustment of cropping structure,i.e.,the expansion of high yield maize crop.The factor decomposition analysis results indicate that the sown area shrinkage only reduced the growth rate of total FCP by 0.29%per year during 1998–2014,although a significant impact was found for the early stage of 1999–2003.The results suggest that the implementation of GFG program would not induce an obvious risk of the food security.Therefore,it is suggested that the GFG program should be set as a long-term strategic policy,by not only supporting the conversion of slope farmlands,but also helping local farmers to seek sustainable ways of land use to improve the income and livelihood.It can be combined with the poverty eradication program,to simultaneously achieve the national goals of ecological civilization building and the livelihood improvement of rural people in the Loess Plateau.Considering rainfall limitation,the conversion of slope farmlands should be prioritized to grasslands.

Monitoring Intra-annual Spatiotemporal Changes in Urban Heat Islands in 1449 Cities in China Based on Remote Sensing

This study aimed to accurately study the intra-annual spatiotemporal variation in the surface urban heat island intensities(SUHIIs) in 1449 cities in China.First, China was divided into five environmental regions.Then, the SUHIIs were accurately calculated based on the modified definitions of the city extents and their corresponding nearby rural areas.Finally, we explored the spatiotemporal variation of the mean, maximum, and minimum values, and ranges of SUHIIs from several aspects.The results showed that larger annual mean daytime SUHIIs occurred in hot-humid South China and cold-humid northeastern China, and the smallest occurred in arid and semiarid west China.The seasonal order of the SUHIIs was summer > spring > autumn > winter in all the temperate regions except west China.The SUHIIs were obviously larger during the rainy season than the dry season in the tropical region.Nevertheless, significant differences were not observed between the two seasons within the rainy or dry periods.During the daytime, the maximum SUHIIs mostly occurred in summer in each region, while the minimum occurred in winter.A few cold island phenomena existed during the nighttime.The maximum SUHIIs were generally significantly positively correlated with the minimum SUHIIs during the daytime, nighttime and all-day in all environmental regions throughout the year and the four seasons.Moreover, significant correlation scarcely existed between the daytime and nighttime ranges of the SUHIIs.In addition, the daytime SUHIIs were also insignificantly correlated with the nighttime SUHIIs in half of the cases.

Spatio-temporal variation of spring phenology in Tibetan Plateau and its linkage to climate change from 1982 to 2012

The influence of climate change on vegetation phenology is a heated issue in current climate change study.We used GIMMS-3g NDVI data to detect the spatio-temporal dynamics of the start of the growing season(SGS) over the Tibetan Plateau(TP) from 1982 to 2012 and to analyze its relationship with temperature and precipitation.No significant trend was observed in the SGS at the regional scale during the study period(R^2 = 0.03,P = 0.352).However,there were three time periods(1982-1999,1999-2008 and 2008-2012) with identifiable,distinctly different trends.Regions with a significant advancing trend were mainly scattered throughout the humid and semi-humid areas,whereas the regions with a significant delaying trend were mostly distributed throughout the semi-arid areas.Statistical analysis showed that the response of the SGS to climate change varies spatially.The SGS was significantly correlated with the spring temperature and the start of the thermal growth season(STGS) in the relatively humid area.With increasing aridity,theimportance of the spring temperature for the SGS gradually decreased.However,the influences of precipitation and winter temperature on the SGS were complicated across the plateau.

Use of the Max Ent model to predict changes in sloth bear(Melursus ursinus)habitats in the Gandaki River Basin,Nepal

The Gandaki River Basin(GRB),located in the central Himalaya,provides habitats for a large number of important flora and fauna species.The habitats of key protected species have changed over time as a result of climate changes and human activities related to land use change,including the development of roads.This study assessed the present and future distributions of sloth bear(Melursus ursinus)habitats using the maximum entropy(Max Ent)model.Bioclimatic data,a digital elevation model and roads were used as environmental layers to assess current and future distributions of habitat.Results show that the overall habitat within the study area is likely to undergo important changes in the future.Bio 8(the mean temperature of the wettest quarter)and slope were found to be important variables affecting the distribution of the species.The habitats very highly suitable for sloth bears currently cover an area of 148 km^(2) within the GRB.These habitats are predicted to increase by 122 km^(2) more by 2050.Overall,a net change by 680.38 km^(2) was found in the GRB.Conservation measures are necessary for this key protected species and its habitat within the GRB and elsewhere in Nepal.