Spatiotemporal changes of gross primary productivity and its response to drought in the Mongolian Plateau under climate change

Gross primary productivity(GPP)of vegetation is an important constituent of the terrestrial carbon sinks and is significantly influenced by drought.Understanding the impact of droughts on different types of vegetation GPP provides insight into the spatiotemporal variation of terrestrial carbon sinks,aiding efforts to mitigate the detrimental effects of climate change.In this study,we utilized the precipitation and temperature data from the Climatic Research Unit,the standardized precipitation evapotranspiration index(SPEI),the standardized precipitation index(SPI),and the simulated vegetation GPP using the eddy covariance-light use efficiency(EC-LUE)model to analyze the spatiotemporal change of GPP and its response to different drought indices in the Mongolian Plateau during 1982-2018.The main findings indicated that vegetation GPP decreased in 50.53% of the plateau,mainly in its northern and northeastern parts,while it increased in the remaining 49.47%area.Specifically,meadow steppe(78.92%)and deciduous forest(79.46%)witnessed a significant decrease in vegetation GPP,while alpine steppe(75.08%),cropland(76.27%),and sandy vegetation(87.88%)recovered well.Warming aridification areas accounted for 71.39% of the affected areas,while 28.53% of the areas underwent severe aridification,mainly located in the south and central regions.Notably,the warming aridification areas of desert steppe(92.68%)and sandy vegetation(90.24%)were significant.Climate warming was found to amplify the sensitivity of coniferous forest,deciduous forest,meadow steppe,and alpine steppe GPP to drought.Additionally,the drought sensitivity of vegetation GPP in the Mongolian Plateau gradually decreased as altitude increased.The cumulative effect of drought on vegetation GPP persisted for 3.00-8.00 months.The findings of this study will improve the understanding of how drought influences vegetation in arid and semi-arid areas.

Spatiotemporal patterns and drivers of cultivated land conversion in Inner Mongolia Autonomous Region,northern China

Protection and optimization of cultivated land resources are of great significance to national food security.Cultivated land conversion in northern China has increased in recent years due to the industrialization and urbanization of society.However,the assessment of cultivated land conversion in this area is insufficient,posing a potential risk to cultivated land resources.This study evaluated the evolution and spatiotemporal patterns of cultivated land conversion in Inner Mongolia Autonomous Region,China,and the driving factors to improve rational utilization and to protect cultivated land resources.The spatiotemporal patterns of cultivated land conversion in Inner Mongolia were analyzed using the cultivated land conversion index,kernel density analysis,a standard deviation ellipse model,and a geographic detector.Results showed that from 2000 to 2020,the trends in cultivated land conversion area and rate in Inner Mongolia exhibited fluctuating growth,with the total area of cultivated land conversion reaching 7307.59 km^(2) at a rate of 6.69%.Spatial distribution of cultivated land conversion was primarily concentrated in the Hetao Plain,Nengjiang Plain,Liaohe Plain,and the Hohhot-Baotou-Ordos urban agglomeration.Moreover,the standard deviational ellipse of cultivated land conversion in Inner Mongolia exhibited a directional southwest-northeast-southwest-northeast distribution,with the northeast-southwest direction identified as the main driving force of spatial change in cultivated land conversion.Meanwhile,cultivated land conversion exhibited an increase-decrease-increase change process,indicating that spatial distribution of cultivated land conversion in Inner Mongolia became gradually apparent within the study period.The geographic detector results further revealed that the main driving factors of cultivated land conversion in Inner Mongolia were the share of secondary and tertiary industries and per-unit area yield of grain,with explanatory rates of 57.00%,55.00%,and 51.00%,respectively.Additionally,improved agricultural production efficiency and the coordinated development of population urbanization and industry resulted in cultivated land conversion.Collectively,the findings of this study indicated that,from 2000 to 2020,the cultivated land conversion in Inner Mongolia was significant and fluctuated in time,and had strong spatial heterogeneity.The primary drivers of these events included the effects of agriculture,population,and social economy.

Response of ecosystem carbon storage to land use change from 1985 to 2050 in the Ningxia Section of Yellow River Basin,China

Regional sustainable development necessitates a holistic understanding of spatiotemporal variations in ecosystem carbon storage(ECS),particularly in ecologically sensitive areas with arid and semi-arid climate.In this study,we calculated the ECS in the Ningxia Section of Yellow River Basin,China from 1985 to 2020 using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model based on land use data.We further predicted the spatial distribution of ECS in 2050 under four land use scenarios:natural development scenario(NDS),ecological protection scenario(EPS),cultivated land protection scenario(CPS),and urban development scenario(UDS)using the patch-generating land use simulation(PLUS)model,and quantified the influences of natural and human factors on the spatial differentiation of ECS using the geographical detector(Geodetector).Results showed that the total ECS of the study area initially increased from 1985 until reaching a peak at 402.36×10^(6) t in 2010,followed by a decreasing trend to 2050.The spatial distribution of ECS was characterized by high values in the eastern and southern parts of the study area,and low values in the western and northern parts.Between 1985 and 2020,land use changes occurred mainly through the expansion of cultivated land,woodland,and construction land at the expense of unused land.The total ECS in 2050 under different land use scenarios(ranked as EPS>CPS>NDS>UDS)would be lower than that in 2020.Nighttime light was the largest contributor to the spatial differentiation of ECS,with soil type and annual mean temperature being the major natural driving factors.Findings of this study could provide guidance on the ecological construction and high-quality development in arid and semi-arid areas.

The discovery of Late Triassic hypabyssal mafic dykes in the Huozhou complex and their geological significance:Evidence from petrology,geochemistry,and geochronology

The Huozhou complex in the Trans-North China Orogen exhibits two events of mafic magmatism(separated by ca.700 Ma):Neoproterozoic(920±15 Ma)Shimenyu diabase and Late Triassic(217±2.5 Ma)Xingtangsi diabase.Investigations have focused on systematic petrology,zircon U-Pb dating,Lu-Hf isotopes,and lithogeochemistry.The research findings indicate that the Late Triassic Xingtangsi diabase of the Huozhou complex can be classified as a transitional type between intermediate and mafic rocks based on their SiO_(2)content.This classification is supported by an average SiO_(2)content of 53.94%,ranging from 53.33%to 54.28%.In the Zr/TiO_(2)vs.Ce diagram,all samples lie within the range of basalt.The zircons from the Late Triassic Xingtangsi diabase have lowε_(Hf)(t)values ranging from-12.7 to-8.7,with an average of-11.1.Additionally,the single-stage model age T_(DM1)is estimated to be between 1207 and 1701 Ma.These findings suggest that the magma responsible for the dyke originated from either partial melting or an enriched mantle source inside the Meso-Proterozoic lithospheric mantle.The elevated concentrations of Th(thorium)and LREEs(light rare earth elements),as well as the Th/Yb and Th/Nb ratios,suggest the potential incorporation of subducted sediments within the magma source region.The rock displays negative Nb,Ta,Zr,Hf,and Ti anomalies.These geochemical attributes align with the distinctive traits observed in volcanic rocks found within island arcs.The formation of the Late Triassic Xingtangsi diabase is likely associated with the geological context of an arc setting,which arises from the collision between the Yangtze plate and the North China Craton.

Effect of salinization on soil properties and mechanisms beneficial to microorganisms in salinized soil remediation-a review

Salinized soil is an important reserved arable land resource in China.The management and utilization of salinized soil can safeguard the current size of arable land and a stable grain yield.Salt accumulation will lead to the deterioration of soil properties,destroy soil production potential and damage soil ecological functions,which in turn will threaten global water and soil resources and food security,and affect sustainable socio-economic development.Microorganisms are important components of salinized soil.Microbial remediation is an important research tool in improving salinized soil and is key to realizing sustainable development of agriculture and the ecosystem.Knowledge about the impact of salinization on soil properties and measures using microorganisms in remediation of salinized soil has grown over time.However,the mechanisms governing these impacts and the ecological principles for microbial remediation are scarce.Thus,it is imperative to summarize the effects of salinization on soil physical,chemical,and microbial properties,and then review the related mechanisms of halophilic and halotolerant microorganisms in salinized soil remediation via direct and indirect pathways.The stability,persistence,and safety of the microbial remediation effect is also highlighted in this review to further promote the application of microbial remediation in salinized soil.The objective of this review is to provide reference and theoretical support for the improvement and utilization of salinized soil.

Changes of Soil Labile Organic Carbon in Different Land Uses in Sanjiang Plain, Heilongjiang Province

In the Sanjiang Plain,Northeast China,the natural wetland is undergoing a rapid conversion into agricultural land,which has resulted in drastic ecological changes in the region. To investigate the effects of different land uses on soil labile organic carbon,soils of Calamagrostis angustifolia wetland,Carex lasiocarpa wetland,dry farmland,paddy field,forest land and abandoned cultivated land were collected for measuring the contents of soil microbial biomass carbon (MBC),dissolved organic carbon (DOC),readily oxidizable carbon (ROC) and carbohydrate carbon (CHC). The results show that soil organic carbon contents follow the order: Carex lasiocarpa wetland>Calamagrostis angustifolia wetland>forest land>paddy field>dry farmland. The contents of MBC and DOC in Calamagrostis angustifolia and Carex lasiocarpa wetlands are significantly higher than those in other land use types. The contents of CHC and ROC are the highest in Calamagrostis angustifolia wetland and the lowest in dry farmland. The contents of all the labile organic carbon increase along with the years of abandonment of cultivated land. The ratios of MBC,DOC and ROC to SOC also follow the order: Carex lasiocarpa wetland>Calamagrostis angustifolia wetland>forest land>paddy field>dry farmland,while the ratio of CHC to SOC is paddy field>forest field>Carex lasiocarpa wetland>Carex lasiocarpa wetland>dry farmland. When natural wetlands were cultivated,the activity of soil organic carbon tends to reduce in some extent due to the disappearance of heterotrophic environment and the reduction of vegetation residue. Thus,the abandonment of cultivated land is an effective way for restoring soil organic carbon.

Bio-geomorphologic features and growth process of Tamarix nabkhas in Hotan River Basin, Xinjiang

Tamarix nabkha is one of the most widespread nabkhas, distributing in the arid region of China. Based on the observations outdoors and the simulation experiments in laboratories, analysis in this paper refers to the biological geomorphologic features and growth process of Tamarix nabkhas in the middle and lower reaches of the Hotan River, Xinjiang. And the results indicate that the ecological type of Tamarix in the study area is a kind of Tugaic soil habitat based on the deep soil of the Populus Diversifolia forests and shrubs. This type of habitat can be divided into three kinds of sub-habitats which demonstrate the features of ecological environment of Tamarix nabkhas during the differential developed phases. Meanwhile, the Tamar, ix nabkha can exert intensified disturbance current on wind-sand flow on the ground,and its root and stems not only have strong potential of sprouting but are characteristic of wind erosion-tolerance, resistance to be buried by sand and respectively tough rigid of the lignified branches, for it has a rather longer life-time. Thus, the wind speed profile influenced by the Tamarix nabkha is different from the Phragmites nabkha and Alhagi nabkha. And the structure of the wind flow is beneficial to aeolian sand accumulating in/around Tamarix shrub, which can create unique Tamarix nabkhas with higher average gradient and longer periodicity of life. Tamarix nabkha evolution in the area experienced three stages： growth stage, mature and steady stage and withering stage. In each stage, morphological features and geomorphic process of Tamarix nabkha are different due to the discrep- ant interaction between the nabkha and aeolian sand flow.

C:N:P stoichiometry of perennial herbs’ organs in the alpine steppe of the northern Tibetan Plateau

The patterns of C:N:P stoichiometry across ecosystems are important in understanding biogeochemical processes. The stoichiometry of nutrients at the leaf and root level have been reported previously, but relationships of other plant organs, such as stems and the reproductive organs, remain unclear. We collected 228 samples of leaves, roots, stems and reproductive organs from 11 common plant species at 25 sites on the Tibetan Plateau to explore the relationships of C:N:P stoichiometry both within and across plant organs. The average C concentrations in the roots, leaves, stems and reproductive organs were 427.32, 410.51, 421.11 and 416.72 mg g-1, respectively. The shoot tissues(leaves, stems and reproductive organs) had significantly higher N and P concentrations than the roots. The N and P concentrations had a significant positive correlation within the same organ. The nutrient concentrations(N and P) and nutrient ratios(C:N, C:P and N:P) were significantly correlated across all pairwise organ combinations. Our data suggest that alpine perennial herbs share similar evolutionary histories and have constrained patterns of covariation for C concentrations, with differential patterns for N and P stoichiometry across organs. Our data also indicate that covarying sets of nutrient traits are consistent across environments and biogeographical regions and demonstrate convergent evolution in plant nutritional characteristics in extreme alpine environments.

Paleo-Tethyan Oceanic Crust Subduction in the Eastern Section of the East Kunlun Orogenic Belt:Geochronology and Petrogenesis of the Qushi'ang Granodiorite

The Qushi’ang granodiorite（QSG） is located at the central east of the ophiolitic melange belt in the East Kunlun Orogenic Belt（EKOB） in the northern margin of the Qinghai-Tibetan Plateau. LA-MC-ICP-MS zircon U–Pb dating suggests that the granodiorite and mafic microgranular enclaves（MMEs） crystallized 246.61±0.62 and 245.45±0.9 Ma ago, respectively. Granodiorite, porphyritic diorite, and MMEs are metaluminous and medium-K calk-alkaline series, with island-arc magma features, such as LILE enrichment and HFSE depletion. The porphyritic diorite has high Cr（13.50 ppm to 59.01 ppm）, Ni（228.53 ppm to 261.29 ppm）, and Mg~#（46–54）. Granodiorite and porphyritic diorite have similar mineral compositions and evolved major and trace elements contents, particularly Cr and Ni, both of which are significantly higher than that in granites of the same period. The crystallization age of MMEs is close to that of granodiorite, and their major and trace elements contents are in-between porphyritic diorite and granodiorite. The results suggest that the original mafic magma, which was the product of mantle melting by subduction process, intruded into the lower crust（Kuhai Rock Group）, resulting in the formation of granodiorite. Countinous intrusion of mafic magma into the unconsolidated granodiorite formed MMEs and porphyritic diorite. The granodiorite reformed by late-stage strike-slip faulting tectonic event indicates that the strike-slip fault of Middle Kunlun and the collision of the Bayanhar block with East Kunlun were later than 246 Ma. Therefore, the formation of the QSG not only indicates the critical period of evolution of East Kunlun but also represents the tectonic transition from oceanic crust subduction to slab breaking.

Spatiotemporal variability of precipitation during 1961-2014 across the Mongolian Plateau

Precipitation is the dominant factor that controls vegetation growth and land-use practices in the arid and semiarid Mongolian Plateau(MP), so the spatiotemporal heterogeneity of precipitation change has been an important scientific question in the region. This study investigated the spatiotemporal characteristics of annual and seasonal precipitation across the entire MP based on monthly precipitation data from 136 meteorological stations during 1961–2014 by using a modified Mann–Kendall test, Sen's slope, Morlet Wavelet Transform, and geostatistical methods. Results show the following: 1) Annual precipitation decreased slightly from 1961 to 2014.Stations with positive and negative trends were 41.9%and 58.1%, respectively. Significant positive trends were mainly in the southwestern and northeastern regions of the plateau, whereas significant negative trends were in the northern and southeastern regions.2) Precipitation decreased at rates of-5.65 and-0.41 mm/decade in summer and autumn, respectively, but increased at 1.91 and 0.51 mm/decade in spring and winter. The contribution of spring and winter precipitation to the annual amount increased significantly, but that of summer precipitation decreased significantly. 3) A large majority of stations(80.2%) showed decreasing trends in summer,whereas 89.7% and 83.1% of stations showed increasing trends in spring and winter. The spatial distribution of trend magnitude in seasonal precipitation amount was strongly heterogeneous. 4)By climatic zones, precipitation increased in humid and arid zones, but decreased in a semiarid zone. On the whole, the MP experienced a drying trend, with significant regional differentiation and seasonal variations.

Regional accessibility of land traffic network in the Yangtze River Delta

In a given district, the accessibility of any point should be the synthetically evaluation of the internal and external accessibilities. Using MapX component and Delphi, the author presents an information system to calculate and analyze regional accessibility according to the shortest travel time, generating thus a mark diffusing figure. Based on land traffic network, this paper assesses the present and the future regional accessibilities of sixteen major cities in the Yangtze River Delta. The result shows that the regional accessibility of the Yangtze River Delta presents a fan with Shanghai as its core. The top two most accessible cities are Shanghai and Jiaxing, and the bottom two ones are Taizhou （Zhejiang province） and Nantong With the construction of Sutong Bridge, Hangzhouwan Bridge and Zhoushan Bridge, the regional internal accessibility of all cities will be improved. Especially for Shaoxing, Ningbo and Taizhou （Jiangsu province）, the regional internal accessibility will be decreased by one hour, and other cities will be shortened by about 25 minutes averagely. As the construction of Yangkou Harbor in Nantong, the regional external accessibility of the harbor cities in Jiangsu province will be speeded up by about one hour.

Characteristics of Wind Erosion and Deposition in Oasis-desert Ecotone in Southern Margin of Tarim Basin,China

The oasis-desert ecotone is a fragile ecological zone that is affected both by oasis and desert conditions. To understand the impact of the differences in wind power, and the influence of wind erosion and deposition on the ecotone, meteorological data and con- temporaneous wind erosion and deposition data were collected on the southern margin of Tarim Basin with serious sand-blown hazards. The wind velocity, average wind velocity, sand drift potential （DP）, resultant sand drift potential （RDP）, and sand transportation rate decrease significantly and successively across four landscape types with increasing vegetation coverage （VC）. Flat surfaces and areas of shifting sandy ground experience intense wind erosion with fast movement of mobile sand dunes; semi-fixed sand areas experience ex- tensive wind deposition but only slight wind erosion; and fixed sand areas experience only slight wind erosion and deposition. Volume of wind erosion on bare newly reclaimed farmland is up to 6.96 times that of bare shifting sandy ground. Wind erosion volume per unit area and VC follow an exponential function relationship in natural conditions, while wind deposition volume per unit area does not conform to any functions which has close relationship with vary topography and arrangement patterns of vegetation besides for VC. The results indicate that the volume of wind erosion has a close correlation with VC, and different types and distribution patterns of topog- raphy and vegetation also profoundly influence the wind deposition volume in the field, and underground water tables in different land- scape types control the plant community distribution. Keywords： wind erosion; wind deposition; oasis-desert ecotone; vegetation coverage （VC）; topography; Cele County

Effects of Rice Straw and Its Biochar Addition on Soil Labile Carbon and Soil Organic Carbon

Whether the biochar amendment could affect soil organic matter （SOM） turnover and hence soil carbon （C） stock remains poorly understood. Effects of the addition of ^13C-labelled rice straw or its pyrolysed biochar at 250 or 350℃ to a sugarcane soil （Ferrosol） on soil labile C （dissolved organic C, DOC; microbial biomass C, MBC; and mineralizable C, MC） and soil organic C （SOC） were investigated after 112 d of laboratory incubation at 25℃. Four treatments were examined as （1） the control soil without amendment （Soil）; （2） soil plus ^13C-labelled rice straw （Soil＋Straw）; （3） soil plus 250℃ biochar （Soil＋B250） and （4） soil plus 350℃biochar （Soil＋B350）. Compared to un-pyrolysed straw, biochars generally had an increased aryl C, carboxyl C, C and nitrogen concentrations, a decreased O-alkyl C and C：N ratio, but similar alkyl C and δ^13C （1 742- 1 877 %）. Among treatments, significant higher DOC, MBC and MC derived from the new C （straw or biochar） ranked as Soil＋Straw〉Soil＋B250〉Soil＋B350, whilst significant higher SOC from the new C as Soil＋B250〉Soil＋Straw≈Soil＋B350. Compared to Soil, DOC and MBC derived from the native soil were decreased under straw or biochar addition, whilst MC from the native soil was increased under straw addition but decreased under biochar addition. Meanwhile, native SOC was similar among the treatments, irrespective of the straw or biochar addition. Compared to Soil, significant higher total DOC and total MBC were under Soil＋Straw, but not under Soil＋B250 and Soil＋B350, whilst significant higher total MC and total SOC were under straw or biochar addition, except for MC under Soil＋B350. Our results demonstrated that the application of biochar to soil may be an appropriate management practice for increasing soil C storage.

Spatiotemporal changes of eco-environmental quality based on remote sensing-based ecological index in the Hotan Oasis,Xinjiang

The rapid economic development that the Hotan Oasis in Xinjiang Uygur Autonomous Region,China has undergone in recent years may face some challenges in its ecological environment.Therefore,an analysis of the spatiotemporal changes in ecological environment of the Hotan Oasis is important for its sustainable development.First,we constructed an improved remote sensing-based ecological index(RSEI)in 1990,1995,2000,2005,2010,2015 and 2020 on the Google Earth Engine(GEE)platform and implemented change detection for their spatial distribution.Second,we performed a spatial autocorrelation analysis on RSEI distribution map and used land-use and land-cover change(LUCC)data to analyze the reasons of RSEI changes.Finally,we investigated the applicability of improved RSEI to arid area.The results showed that mean of RSEI rose from 0.41 to 0.50,showing a slight upward trend.During the 30-a period,2.66% of the regions improved significantly,10.74% improved moderately and 32.21% improved slightly,respectively.The global Moran's I were 0.891,0.889,0.847 and 0.777 for 1990,2000,2010 and 2020,respectively,and the local indicators of spatial autocorrelation(LISA)distribution map showed that the high-high cluster was mainly distributed in the central part of the Hotan Oasis,and the low-low cluster was mainly distributed in the outer edge of the oasis.RSEI at the periphery of the oasis changes from low to high with time,with the fragmentation of RSEI distribution within the oasis increasing.Its distribution and changes are predominantly driven by anthropologic factors,including the expansion of artificial oasis into the desert,the replacement of desert ecosystems by farmland ecosystems,and the increase in the distribution of impervious surfaces.The improved RSEI can reflect the eco-environmental quality effectively of the oasis in arid area with relatively high applicability.The high efficiency exhibited with this approach makes it convenient for rapid,high frequency and macroscopic monitoring of eco-environmental quality in study area.

Effect of temperature on soil respiration in a Chinese fir forest

Soil samples collected from the surface soil （0-10 cm） in an 88-year-old Chinese fir （Cunninghamia lanceolata） forest in Nanping Fujian, China were incubated for 90 days at the temperatures of 15℃, 25℃ and 35℃ in laboratory. The soil CO2 evolution rates were measured at the incubation time of 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 and 90 days. The results showed that CO2 evolution rates of soil samples varied significantly with incubation time and temperature during the incubation period. Mean CO2 evolution rate and cumulative amount of CO2 evolution from soil were highest at 35℃, followed by those at 25℃, and 15℃. Substantial differences in CO2 evolution rate were found in Q10 values calculated for the 2nd and 90th day of incubation. The Q10 value for the average CO2 evolution rate was 2.0 at the temperature range of 15-25℃, but it decreased to 1.2 at 25 35℃. Soil CO2 evolution rates decreased with the incubation time. The cumulative mineralized C at the end of incubation period （on the 90th day） was less than 10% of the initial C amounts prior to incubation.

Spatial-temporal Evolution Characteristics and Decoupling Analysis of Influencing Factors of China’s Aviation Carbon Emissions

The aviation industry has become one of the top ten greenhouse gas emission industries in the world. China’s aviation carbon emissions continue to increase, but the analysis of its influencing factors at the provincial level is still incomplete. This paper firstly uses Stochastic Impacts by Regression on Population, Affluence and Technology model(STIRPAT) model to analyze the time series evolution of China’s aviation carbon emissions from 2000 to 2019. Secondly, it uses the Logarithmic Mean Divisia Index(LDMI) model to analyze the influencing characteristics and degree of four factors on China’s aviation carbon emissions, which are air transportation revenue, aviation route structure, air transportation intensity and aviation energy intensity. Thirdly, it determines the various factors’ influencing direction and evolution trend of 31 provinces’ aviation carbon emissions in China(not including Hong Kong, Macao, Taiwan of China due to incomplete data). Finally, it derives the decoupling effort model and analyzes the decoupling relationship and decoupling effort degree between air carbon emissions and air transportation revenue in different provinces. The study found that from 2000 to2019, China’s total aviation carbon emissions continued to grow, while the growth rate of aviation carbon emissions showed a fluctuating downward trend. Air transportation revenue and aviation route structure promote the growth of total aviation carbon emissions, and air transportation intensity and aviation energy intensity have a restraining effect on the growth of total aviation carbon emissions. The scope of negative driving effect of air transportation revenue and air transportation intensity on total aviation carbon emissions in various provinces has increased. While the scope of positive driving influence of aviation route structure on total aviation carbon emissions of various provinces has increased, aviation energy intensity mainly has negative driving influence on total aviation carbon emissions of each province. Overall, the emission reduction trend in the areas to the west and north of the Qinling-Huaihe River Line is obvious. The decoupling mode between air carbon emissions and air transportation revenue in 31 provinces is mainly expansion negative decoupling.The air transportation intensity effect shows strong decoupling efforts in most provinces, the decoupling effort of aviation route structure effect and aviation energy intensity effect is not prominent.

Spatiotemporal features of soil and water loss in Three Gorges Reservoir Area of Chongqing

Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing.In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to 2004 based on RS and GIS techniques.The results showed that:(1) The soil and water loss area decreased from 1999 to 2004.(2) Soil and water loss mainly exists in purple soil,yellow soil,limestone soil,paddy soil and yellow brown soil distributed areas.(3) The dry slope land and sparse woodland that are intensively influenced by human activities experienced most serious soil and water loss.(4) Soil and water loss in the study area indicated an obvious vertical differentiation characteristic.(5) There is a significant correlation between soil and water loss and slope.(6) There is no obvious correlation between soil and water loss and aspect.(7) Soil and water loss mainly exists in the values of R between 300 and 340 distribution area.The very-high soil and water loss has obvious correlation with R.

Spatial-temporal Evolution of the Urban-rural Coordination Relationship in Northeast China in 1990-2018

To comprehensively understand the law of urban-rural relationship and propose scientific measures of urban-rural coordinated development in Northeast China,this study uses the coupling coordination degree model and geographically and temporally weighted regression(GTWR)model to analyze the spatial-temporal patterns and the corresponding driving mechanisms of its urban-rural coordination since 1990.The results are as follows.First,the urban-rural coupling coordination degree in Northeast China was very low and improved slowly,but its stages of evolution is a good interpretation of the strategic arrangements of China's urbanization.Second,the urban-rural coupling coordination degree in Northeast China had spatial differences and was characterized by central polarization,converging on urban agglomeration,which was high in the south and low in the north.Moreover,the gap between the north and south weakened.Third,the spatial-temporal evolution of the urban-rural coordination relationship in Northeast China was influenced by pulling from the central cities,pushing from rural transformation,and government regulations.The influence intensity of the three mechanisms was weak,but the pulling from the central cities was stronger than that of the other two mechanisms.Furthermore,the spatial difference between the three mechanisms determines the spatial pattern and its evolution of the urban-rural coordination relationship in Northeast China.Fourth,to promote the development of urban-rural coordination in Northeast China,it is essential to advance urban-rural economic correlation,enhance the government^role in regulating and guiding,and adopt different policies for each region in Northeast China.

Late Pleistocene aeolian activity in Haitan Island, Southeast China: Insights from optically stimulated luminescence dating of coastal dunes on marine terraces

The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.

Landslide Susceptibility Assessment of the Youfang Catchment using Logistic Regression

A detailed landslide susceptibility map was produced in the Youfang catchment using logistic regression method with datasets developed for a geographic information system(GIS).Known as one of the most landslide-prone areas in China, the Youfang catchment of Longnan mountain region,which lies in the transitional area among QinghaiTibet Plateau, loess Plateau and Sichuan Basin, was selected as a representative case to evaluate the frequency and distribution of landslides.Statistical relationships for landslide susceptibility assessment were developed using landslide and landslide causative factor databases.Logistic regression(LR)was used to create the landslide susceptibility maps based on a series of available data sources: landslide inventory; distance to drainage systems, faults and roads; slope angle and aspect; topographic elevation and topographical wetness index, and land use.The quality of the landslide susceptibility map produced in this paper was validated and the result can be used fordesigning protective and mitigation measures against landslide hazards.The landslide susceptibility map is expected to provide a fundamental tool for landslide hazards assessment and risk management in the Youfang catchment.