Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneuro ns.Howeve r,current research on the spatial location of the spinal motoneuro...Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneuro ns.Howeve r,current research on the spatial location of the spinal motoneurons innervating differe nt muscles is limited.In this study,we investigated the spatial distribution and relative position of different motoneurons that control the deep muscles of the mouse hindlimbs,which were innervated by the obturator nerve,femoral nerve,inferior gluteal nerve,deep pe roneal nerve,and tibial nerve.Locations were visualized by combining a multiplex retrograde tracking technique compatible with three-dimensional imaging of solvent-cleared o rgans(3DISCO)and 3-D imaging technology based on lightsheet fluorescence microscopy(LSFM).Additionally,we propose the hypothesis that"messenger zones"exist as interlaced areas between the motoneuron pools that dominate the synergistic or antagonist muscle groups.We hypothesize that these interlaced neurons may participate in muscle coordination as messenger neurons.Analysis revealed the precise mutual positional relationships among the many motoneurons that innervate different deep muscles of the mouse.Not only do these findings update and supplement our knowledge regarding the overall spatial layout of spinal motoneurons that control mouse limb muscles,but they also provide insights into the mechanisms through which muscle activity is coordinated and the architecture of motor circuits.展开更多
The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals.In this paper,a novel three-dimensional(3D)grain-based model(GBM)based on particle flow cod...The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals.In this paper,a novel three-dimensional(3D)grain-based model(GBM)based on particle flow code(PFC),i.e.PFC3D-GBM,is proposed.This model can accomplish the grouping of mineral grains at the 3D scale and then filling them.Then,the effect of the position distribution,geometric size,and volume composite of mineral grains on the cracking behaviour and macroscopic properties of granite are examined by conducting Brazilian splitting tests.The numerical results show that when an external load is applied to a sample,force chains will form around each contact,and the orientation distribution of the force chains is uniform,which is independent of the external load level.Furthermore,the number of high-strength force chains is proportional to the external load level,and the main orientation distribution is consistent with the external loading direction.The main orientation of the cracks is vertical to that of the high-strength force chains.The geometric size of the mineral grains controls the mechanical behaviours.As the average grain size increases,the number of transgranular contacts with higher bonding strength in the region connecting both loading points increases.The number of high-strength force chains increases,leading to an increase in the stress concentration value required for the macroscopic failure of the sample.Due to the highest bonding strength,the generation of transgranular cracks in quartz requires a higher concentrated stress value.With increasing volume composition of quartz,the number of transgranular cracks in quartz distributed in the region connecting both loading points increases,which requires many high-strength force chains.The load level rises,leading to an increase in the tensile strength of the numerical sample.展开更多
Water-induced landslides in hydropower reservoirs pose a great threat to both project operation and human life.This paper examines three large reservoirs in Sichuan Province,China.Field surveys,site monitoring data an...Water-induced landslides in hydropower reservoirs pose a great threat to both project operation and human life.This paper examines three large reservoirs in Sichuan Province,China.Field surveys,site monitoring data analyses and numerical simulations are used to analyze the spatial distribution and failure mechanisms of water-induced landslides in reservoir areas.First,the general rules of landslide development in the reservoir area are summarized.The first rule is that most of the landslides have rear edge elevations of 100e500 m above the normal water level of the reservoir,with volumes in the range of 106 e107 m 3.When the volume exceeds a certain amount,the number of sites at which the landscape can withstand landslides is greatly reduced.Landslide hazards mainly occur in the middle section of the reservoir and less in the annex of the dam site and the latter half of the reservoir area.The second rule is that sedimentary rocks such as sandstone are more prone to landslide hazards than other lithologies.Then,the failure mechanism of changes in the water level that reduces the stability of the slope composed of different geomaterials is analyzed by a proposed slope stability framework that considers displacement and is discussed with the monitoring results.Permeability is an essential parameter for understanding the diametrically opposed deformation behavior of landslides experiencing filling-drawdown cycles during operation.This study seeks to provide inspiration to subsequent researchers,as well as guidance to technicians,on landslide prevention and control in reservoir areas.展开更多
Historical and current climate impacts reshape the evolutionary trajectory and ecological dynamics of entire vegetative communities,which can drive insect species distribution.Understanding the spatial distribution of...Historical and current climate impacts reshape the evolutionary trajectory and ecological dynamics of entire vegetative communities,which can drive insect species distribution.Understanding the spatial distribution of insects can enhance forest management effectiveness.The effects of historical and current climates in the spatial distribution of herbivorous tree insects in China were explored.A species distribution model simulated insect spatial distribution based on 596 species and the distribution probability and richness of these species were assessed in forest ecoregions.The explanatory power of the historical climate was stronger than that of the current climate,particularly historical annual precipitation and annual mean temperatures,for the distribution of herbivorous insects.Under both historical and current climatic conditions,herbivorous tree insects were and are mainly distributed in the North China Plain and the middle and lower reaches of the Yangtze River Plain,namely in the Huang He Plain mixed forests,Changjiang Plain evergreen forests,and Sichuan Basin evergreen broadleaf forests.The Yunnan-Guizhou Plateau and northeast China are regions with large impact differences between historical and current climates.The findings of this study provide valuable insights into herbivorous insect responses to sustained climate change and may contribute to long-term biodiversity conservation activities.展开更多
The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic...The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 m.The southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer monsoon.The hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of Bengal.The hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate water.These new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.展开更多
Remote mountainous villages are at risk of falling back into poverty,despite having been lifted out of extreme poverty.However,there has been a lack of focus on the factors contributing to povertyreturn in these villa...Remote mountainous villages are at risk of falling back into poverty,despite having been lifted out of extreme poverty.However,there has been a lack of focus on the factors contributing to povertyreturn in these villages,which making it difficult to understand the risks and their underlying causes.This study investigates the spatial distribution of 546 key assistance villages(KAVs)in the Liangshan mountainous region,a former poverty-stricken area,using the average nearest neighbor(ANN)and kernel density estimation(KDE)methods.Linear regression and geographically weighted regression(GWR)models are then employed to analyze the relationship between the KAVs'economy and potential povertyreturning factors.The results show that KAVs are primarily located in elevation ranges of 1800-2500 m(31.87%),with slopes of 6°-15°(42.67%)and 2-3 km from the township(28.94%).The distribution of KAVs exhibits distinct spatial clustering,forming four gathering areas.Several factors impact the KAVs'economy positively,including the normalized difference vegetation index(NDVI),built-up area,grassland,and education facilities,while elevation has a negative effect.The built-up area has the most critical impact on the rural economy,followed by NDVI and elevation.Additionally,education facilities and grassland areas also have significant effects.The study suggests promoting the Ex-situ Poverty Alleviation Relocation Program(ESPARP)and increasing rural built-up areas,grasslands,and educational facilities as practical measures for preventing poverty return and promoting economic development promotion in remote mountain villages.展开更多
In this study, we used high-resolution optical satellite images on the Google Earth platform to map large-scale landslides in Xianyang City, Shaanxi Province, China. After mapping, a comprehensive and detailed large-s...In this study, we used high-resolution optical satellite images on the Google Earth platform to map large-scale landslides in Xianyang City, Shaanxi Province, China. After mapping, a comprehensive and detailed large-scale landslide inventory that contains 2 924 large-scale landslides was obtained. We analyzed the spatial distribu-tion of landslides with seven influencing factors, including elevation, slope angle, aspect, curvature, lithology, distance to a river, and distance to the fault. Landslide Number, Landslide Area, Landslide Number Density(LND), and Landslide Area Percentage(LAP) were selected as indexes for the spatial distribution analysis. The results show that the number and area of landslides in the elevation range of 1 000–1 200 m is the highest. The highest number of landslides was observed in the slope angle of 25°–30°. North-facing slopes are prone to sliding. The area and number of landslides are the largest when the slope curvature ranges from-1.28 to 0. The LND and LAP reach their maxima when the slope curvature is less than-2.56. Areas covered by the Tertiary stratum with weakened fine-grained sandstone and siltstone show the highest LND and LAP values. Regarding distance to a river, the LAP peaks in the range of 300–600 m, whereas the LND peaks in an area larger than 2100 m. The values of LND and LNP rise as the distance from the faults increases, except for the locations 30 km away from active faults. This phenomenon is because active faults in this area pass through the plain areas, while landslides mostly occur in mountainous areas. The cataloging of landslide development in Xianyang City provides a significant scientific foundation for future research on landslides. In addition, the spatial distribution results are useful for landslide hazard prevention decisions and provide valuable references in this area.展开更多
As an important type of world heritage sites,cultural landscape has always been an important research subject.In order to explore the spatial distribution and evolution mode of cultural landscape all over the world,th...As an important type of world heritage sites,cultural landscape has always been an important research subject.In order to explore the spatial distribution and evolution mode of cultural landscape all over the world,the paper systematically elaborated the historical context of cultural landscape.The distribution characteristics were analyzed by statistical methods,and the connotation and evolution law represented by cultural landscape in different regions were expounded.The word frequency of regional heritage criteria was analyzed,and the local characteristics of each case were discussed.The research shows that the spatial distribution of global cultural landscape is unbalanced,mainly concentrated in Europe,and the spatial distribution characteristics are closely related to geographical environment,social history,economic development level and many other factors.In terms of inscribed criteria for world heritage sites,most cultural landscapes are mainly based on cultural criteria,but also involve natural criteria.The recognition and protection of cultural landscapes that simultaneously meet multiple criteria will become the focus in the future.展开更多
From January 2020 to December 2021,Ulanqab Meteorological Bureau of Inner Mongolia used VLF/LF lightning locator to carry out three-dimensional lightning monitoring in Ulanqab City,and compared with ADTD lightning loc...From January 2020 to December 2021,Ulanqab Meteorological Bureau of Inner Mongolia used VLF/LF lightning locator to carry out three-dimensional lightning monitoring in Ulanqab City,and compared with ADTD lightning location data in the same period.The results show that both VLF/LF lightning locator and ADTD lightning locator had excellent monitoring ability for lightning during flood season in Ulanqab.VLF/LF lightning locator was slightly superior to ADTD lightning locator in observation accuracy,the observation ability of low-current cloud-to-ground lightning,intracloud lightning observation and so on.There were obvious temporal and spatial characteristics of cloud-to-ground lightning during flood season in Ulanqab,and there was a certain correlation between the areas where lightning appeared frequently and surface water.Intracloud lightning was mainly concentrated at a height of 1-7 km.Negative cloud-to-ground lightning accounted for about 75%of total cloud-to-ground lightning,and negative intracloud lightning accounted for 39%of total intracloud lightning.展开更多
Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical ...Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical and representative. In this study, the relationship between settlements and topography, rivers and transportation, and the spatial distribution patterns of settlements, such as the aggregation and orientation characteristics of settlements, have been studied. The main conclusions include: 1) The settlement density decreases with the increase of elevation, slope, and distance from rivers and roads;76.25% and 63.17% of the settlements are distributed in the range of elevation 1500 - 3000 m and slope 6° - 25°, the upper reaches of the Min River are mostly alpine valley terrain, the bottom of the river has a low altitude, the landscape is undulating. The warm and humid climate is suitable for farming, conducive to agricultural production, and an ideal living environment for mountain residents. 2) The nuclear density of the settlement is distributed in strips along the axis of the river, and the closer to the river, the greater the nuclear density value. 3) Mathematical statistical methods were applied for the first time to realize the quantitative expression of the coupling of settlement and river direction. The influence of topographic conditions in different watersheds on the coupling degree of settlement extension and river flow direction was revealed. The slope of the fitted straight line between the settlement and river direction was 0.897, and the two directions were consistent. Except for the mainstream of the Min River, the larger values of the standard deviation ellipse flattening of settlements in each basin appeared in the upper reaches of the bay, and the overall trend showed a gradual decrease from the upstream to the downstream, which was consistent with the topographic change characteristics of the basin.展开更多
Basic infrastructures and services present an important socio-economic and territorial equity issue, because the availability of these makes it possible to improve the living conditions of populations, makes territori...Basic infrastructures and services present an important socio-economic and territorial equity issue, because the availability of these makes it possible to improve the living conditions of populations, makes territories attractive and stimulates their development. The objective of our study has been achieved, so our results provided information on the rate of propagation of basic infrastructures and services, as well as the evolution of the forms of spatial distribution of the latter. The data used comes from the census and geolocation of basic infrastructures and services in the Niakhar area, carried out by the IRD in 2018. Centrographic measurements were used to describe the overall spatial distribution and the use of chi-square statistics confirmed the existence of a preferential direction of distribution. To verify the existence of a spatial structure of infrastructure and service seeding, the Ripley statistic is used. Our results can be useful for land use planning and spatial resource allocation policies. Indeed, the identification of different types of spatial aggregates and the highlighting of the preferred directions of the distribution of basic infrastructures and services, make it possible to correct disparities in the spatial distribution of basic resources.展开更多
As cultural facilities,physical bookstore is an important part of urban infrastructure.Influenced by the development of social economy and the internet,physical bookstores also have become a combination of cultural sp...As cultural facilities,physical bookstore is an important part of urban infrastructure.Influenced by the development of social economy and the internet,physical bookstores also have become a combination of cultural space and tourism experience.In this case,it is necessary to explore the spatial characteristics and influencing factors of physical bookstores.This study uses Density-Based Spatial Clustering of Applications with Noise(DBSCAN),spatial analysis and geographical detectors to calculate the spatial distribution pattern and factors influencing physical bookstores in national central cities/municipality(hereafter using cities)in western China.Based on spatial data,population density,road density and other data,this study constructed a data set of the influencing factors of physical bookstores,consisting of 11 factors along 6 dimensions for 3 national central cities in western China.The results are as follows:first,the spatial distribution pattern of physical bookstores in Xi’an,Chengdu,and Chongqing is unbalanced.The spatial distribution of physical bookstores in Xi’an and Chongqing is from southwest to northeast and are relatively clustered,while those in Chengdu are relatively discrete.Second,the spatial distribution pattern of physical bookstores has been formed under the influence of different factors.The intensity and significance of influencing factors differ in the case cities.However,in general,the social factor,business factor,the density of research facilities,tourism factor and road density are the main driving factors in the three cities.There is a synergistic relationship between public libraries and physical bookstores.Third,the explanatory power becomes stronger after the interaction between various factors.In Xi’an and Chengdu,the density of communities and the density of research facilities have stronger explanatory power for the dependent variable after interacting with other factors.However,in Chongqing,the traffic factors have stronger explanatory power for the dependent variable after interacting with other factors.The results could provide a practical reference for the sustainable development of physical bookstores and encourage a love of reading among the public.展开更多
Salvia miltiorrhiza and S.grandifolia are rich in diterpenoids and have therapeutic effects on cardiovascular diseases.In this study,the spatial distribution of diterpenoids in both species was analyzed by a combinati...Salvia miltiorrhiza and S.grandifolia are rich in diterpenoids and have therapeutic effects on cardiovascular diseases.In this study,the spatial distribution of diterpenoids in both species was analyzed by a combination of metabolomics and mass spectrometry imaging techniques.The results indicated that diterpenoids in S.miltiorrhiza were mainly abietane-type norditerpenoid quinones with a furan or dihydrofuran D-ring and were mainly distributed in the periderm of the roots,e.g.cryptotanshinone and tanshinone IIA.The compounds in S.grandifolia were mainly phenolic abietane-type tricyclic diterpenoids with six-or seven-membered C-rings,and were widely distributed in the periderm,phloem,and xylem of the roots,e.g.11-hydroxy-sugiol,11,20-dihydroxy-sugiol,and 11,20-dihydroxy-ferruginol.In addition,the leaves of S.grandifolia were rich in tanshinone biosynthesis precursors,such as 11-hydroxy-sugiol,while those of S.miltiorrhiza were rich in phenolic acids.Genes in the upstream pathway of tanshinone biosynthesis were highly expressed in the root of S.grandifolia,and genes in the downstream pathway were highly expressed in the root of S.miltiorrhiza.Here,we describe the specific tissue distributions and mechanisms of diterpenoids in two Salvia species,which will facilitate further investigations of the biosynthesis of diterpenoids in plant synthetic biology.展开更多
Growing public awareness of the importance of protecting biodiversity requires the development of forest practices that increase the complexity of stand structure.Understanding the ecological processes of different fo...Growing public awareness of the importance of protecting biodiversity requires the development of forest practices that increase the complexity of stand structure.Understanding the ecological processes of different forest vegetation provide insights into community coexistence mechanisms.In this paper,the spatial patterns of three different communities,evergreen broadleaf forest,deciduous broadleaf forest,and mixed needleleaf and broadleaf forest at Mt.Huangshan,China,were quantified with four structural parameters,the mingling index,the uniform angle index,the diameter dominance index and the crowdedness index.All trees with a diameter at breast height of more than 5 cm were measured.Our analyses highlighted that most trees in the three communities were extremely dense and slightly clumped,with a moderate size differentiation and high mixed structure.In mixed needleleaf and broadleaf forest,the distribution pattern of tree species was better than the other two forests.Overall,spatial patterns in mixed needleleaf and broadleaf forest exhibited a strong stability-effect,that is,the stand had a suitable environment for the stable survival of the forest.With the increasing of elevation,the degree of the mingling index and the crowdedness index increased,however,there was no influence on the uniform angle index and the diameter dominance index.Further,at the same elevation,four structural parameters of shady slope were larger than that of sunny slope.Then we found the relationship between stand spatial structure and environment factors had important influence on forest structure.Our work contributes to the knowledge of population structure,and further provide theoretical basis for the sustainable development of forest resources and protecting biodiversity of Huangshan Mountain.In future studies,it is necessary to explore the limiting factors of community spatial distribution by combining species diversity and functional traits.展开更多
Village classification is the first step to implementing China’s rural revitalization(RR)strategy,and understanding the geographic differences in the distribution of village types helps to grasp the pathway of their ...Village classification is the first step to implementing China’s rural revitalization(RR)strategy,and understanding the geographic differences in the distribution of village types helps to grasp the pathway of their unique development.This study spatialized9250 villages in Jilin Province(divided into six types)of China,and their distribution characteristics and influencing factors were examined using methods such as kernel density estimation,Ripley’s K function,the co-location quotient,and Geodetector.The results indicate that the spatial distribution balance and density of village types are different.All types of villages show an agglomeration distribution pattern,but the scale and intensity vary.There is a strong spatial association between agglomerative promotion(AP)and stable improvement(SIm)villages,as well as between characteristic protection(CP)and prospering frontier and enriching people(PE)villages.The factors affecting their distribution include terrain undulation,the percentage of arable land,the distance to the county town,road network density,population density,gross domestic product(GDP),and industrial enterprise density.The influencing factors for the distribution of village types are closely related to the function of each village.Based on the differences in the spatial distribution and influencing factors of different village types,policy suggestions are given for classified development.展开更多
We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of t...We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang(Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns dif fered in the two lakes and were af fected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish >45 cm(smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes.展开更多
Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional c...Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.展开更多
Carex tussock plays an important role in supporting biodiversity and carbon sequestration of wetland ecosystems,while it is highly threatened by climate change and anthropogenic activities.Therefore,identifying the po...Carex tussock plays an important role in supporting biodiversity and carbon sequestration of wetland ecosystems,while it is highly threatened by climate change and anthropogenic activities.Therefore,identifying the potential distribution patterns of Carex tussocks wetland is vital for their targeted conservation and restoration.The current and future(2050s and 2070s)potential habitats distribution of Carex tussocks in Northeast China were predicted using a Maximum Entropy(Maxent)model based on 68 current data of Carex tussock distributions and three groups of environmental variables(bioclimate,topography,soil properties).Results show that isothermality,seasonal precipitation variability and altitude are important factors that determine the distribution of Carex tussock.The high suitable habitat of Carex tussock is about 5.7×10^(4)km^(2) and mainly distributed in the Sanjiang Plain,Songnen Plain,Changbai Mountains and Da Hinggan Mountains.The area of stable habitats of Carex tussock is significantly higher than the lost and expanded habitats in the future climate scenarios,and the unsuitable habitats mainly occur in Da Hinggan Mountains,Xiao Hinggan Mountains and Changbai Mountains.Overall,Carex tussock wetlands at high altitude and high latitude are more sensitive to climate change,and more attention should be invested in high latitude and high altitude areas.展开更多
By using geography quantitative methods and Arc GIS,the spatial distribution characteristics,types,rules and influencing factors of 20 representative rural tourism attractions in Yangzhou City were analyzed.The result...By using geography quantitative methods and Arc GIS,the spatial distribution characteristics,types,rules and influencing factors of 20 representative rural tourism attractions in Yangzhou City were analyzed.The results show that the traffic accessibility of various regions in Yangzhou City correlated positively with the spacial distribution of rural tourist attractions in quantity in these regions.The rural tourist attractions were dense in regions 10-20 km away from the center of the city;there was only one rural tourist attraction in regions 40-70 km away from the center of the city;some big rural tourist attractions were distributed in regions 70-90 km away from the center of the city;market orientation influenced the spatial distribution of the rural tourist attractions obviously.In regions 0-30 km away from the center of the city,most rural tourist attractions mainly provided recreation and entertainment services for tourists;in regions more than 70 km away from the center of the city,most rural tourist attractions mainly provided health and recuperation services for tourists;in regions 30-50 km away from the center of the city,the service functions of the rural tourist attractions were compound and diversified.展开更多
China is vigorously implementing a rural revitalization strategy with the prosperity of rural industries as the primary goal.The characteristic economy of’One Village One Product’(OVOP)is particularly significant in...China is vigorously implementing a rural revitalization strategy with the prosperity of rural industries as the primary goal.The characteristic economy of’One Village One Product’(OVOP)is particularly significant in promoting rural revitalization and increasing farmers’income.Accurately identifying the spatial distribution characteristics and influencing factors of agricultural specialized villages(ASVs)under OVOP provides a preliminary research basis for constructing the theoretical framework of specialization and clustering of rural industrial development.This study takes Guangdong Province,China as an example,using kernel density estimation,Ripley’s K function,geometric fractals,principal component regression and other methods to identify the spatial distribution characteristics and influencing factors of ASVs.It was found that the ASVs in Guangdong Province are dominated by the planting industry,with an uneven number in space and a multi patch distribution.Specifically,ASVs are mainly distributed in the Chaoshan Plain in the eastern Guangdong,the northern mountainous area of Guangzhou,and the eastern part of Maoming City.Its spatial distribution mode obeys the aggregation distribution pattern at the scale of province,region and municipality(prefecture-level city).In addition,the formation and development of ASVs are affected by multiple internal and external factors.The influence of basic factors such as natural environmental conditions is gradually weakening,while the influence of social and economic factors such as market demand is gradually increasing.This study can enrich the research results of ASVs and provide guidance and reference for the long-term and high-quality development of rural industry revitalization.展开更多
基金supported by the Chinese National General Program of the National Natural Science Foundation of China,No.82072162(to XY)。
文摘Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneuro ns.Howeve r,current research on the spatial location of the spinal motoneurons innervating differe nt muscles is limited.In this study,we investigated the spatial distribution and relative position of different motoneurons that control the deep muscles of the mouse hindlimbs,which were innervated by the obturator nerve,femoral nerve,inferior gluteal nerve,deep pe roneal nerve,and tibial nerve.Locations were visualized by combining a multiplex retrograde tracking technique compatible with three-dimensional imaging of solvent-cleared o rgans(3DISCO)and 3-D imaging technology based on lightsheet fluorescence microscopy(LSFM).Additionally,we propose the hypothesis that"messenger zones"exist as interlaced areas between the motoneuron pools that dominate the synergistic or antagonist muscle groups.We hypothesize that these interlaced neurons may participate in muscle coordination as messenger neurons.Analysis revealed the precise mutual positional relationships among the many motoneurons that innervate different deep muscles of the mouse.Not only do these findings update and supplement our knowledge regarding the overall spatial layout of spinal motoneurons that control mouse limb muscles,but they also provide insights into the mechanisms through which muscle activity is coordinated and the architecture of motor circuits.
基金the financial support of the National Natural Science Foundation of China(Grant No.52179118)the Graduate Innovation Program of China University of Mining and Technology(Grant No.2022WLKXJ032)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX22_2581).
文摘The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals.In this paper,a novel three-dimensional(3D)grain-based model(GBM)based on particle flow code(PFC),i.e.PFC3D-GBM,is proposed.This model can accomplish the grouping of mineral grains at the 3D scale and then filling them.Then,the effect of the position distribution,geometric size,and volume composite of mineral grains on the cracking behaviour and macroscopic properties of granite are examined by conducting Brazilian splitting tests.The numerical results show that when an external load is applied to a sample,force chains will form around each contact,and the orientation distribution of the force chains is uniform,which is independent of the external load level.Furthermore,the number of high-strength force chains is proportional to the external load level,and the main orientation distribution is consistent with the external loading direction.The main orientation of the cracks is vertical to that of the high-strength force chains.The geometric size of the mineral grains controls the mechanical behaviours.As the average grain size increases,the number of transgranular contacts with higher bonding strength in the region connecting both loading points increases.The number of high-strength force chains increases,leading to an increase in the stress concentration value required for the macroscopic failure of the sample.Due to the highest bonding strength,the generation of transgranular cracks in quartz requires a higher concentrated stress value.With increasing volume composition of quartz,the number of transgranular cracks in quartz distributed in the region connecting both loading points increases,which requires many high-strength force chains.The load level rises,leading to an increase in the tensile strength of the numerical sample.
基金We gratefully acknowledge the support of the National Key R&D Program of China(Grant No.2017YFC1501102)the National Nat-ural Science Foundation of China(Grant No.41977229)the Sichuan Youth Science and Technology Innovation Research Team Project(Grant No.2020JDTD0006).
文摘Water-induced landslides in hydropower reservoirs pose a great threat to both project operation and human life.This paper examines three large reservoirs in Sichuan Province,China.Field surveys,site monitoring data analyses and numerical simulations are used to analyze the spatial distribution and failure mechanisms of water-induced landslides in reservoir areas.First,the general rules of landslide development in the reservoir area are summarized.The first rule is that most of the landslides have rear edge elevations of 100e500 m above the normal water level of the reservoir,with volumes in the range of 106 e107 m 3.When the volume exceeds a certain amount,the number of sites at which the landscape can withstand landslides is greatly reduced.Landslide hazards mainly occur in the middle section of the reservoir and less in the annex of the dam site and the latter half of the reservoir area.The second rule is that sedimentary rocks such as sandstone are more prone to landslide hazards than other lithologies.Then,the failure mechanism of changes in the water level that reduces the stability of the slope composed of different geomaterials is analyzed by a proposed slope stability framework that considers displacement and is discussed with the monitoring results.Permeability is an essential parameter for understanding the diametrically opposed deformation behavior of landslides experiencing filling-drawdown cycles during operation.This study seeks to provide inspiration to subsequent researchers,as well as guidance to technicians,on landslide prevention and control in reservoir areas.
基金supported by the National Natural Science Foundation of China (Nos.31800449 and 31800464)。
文摘Historical and current climate impacts reshape the evolutionary trajectory and ecological dynamics of entire vegetative communities,which can drive insect species distribution.Understanding the spatial distribution of insects can enhance forest management effectiveness.The effects of historical and current climates in the spatial distribution of herbivorous tree insects in China were explored.A species distribution model simulated insect spatial distribution based on 596 species and the distribution probability and richness of these species were assessed in forest ecoregions.The explanatory power of the historical climate was stronger than that of the current climate,particularly historical annual precipitation and annual mean temperatures,for the distribution of herbivorous insects.Under both historical and current climatic conditions,herbivorous tree insects were and are mainly distributed in the North China Plain and the middle and lower reaches of the Yangtze River Plain,namely in the Huang He Plain mixed forests,Changjiang Plain evergreen forests,and Sichuan Basin evergreen broadleaf forests.The Yunnan-Guizhou Plateau and northeast China are regions with large impact differences between historical and current climates.The findings of this study provide valuable insights into herbivorous insect responses to sustained climate change and may contribute to long-term biodiversity conservation activities.
基金supported by the National Natural Science Foundation of China(No.41806099)the Global Change and Air-Sea Interaction Project of China(No.GASI-04-HYST-06).
文摘The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 m.The southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer monsoon.The hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of Bengal.The hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate water.These new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.
基金supported by the Sichuan Province Science and Technology Support Program(Grant No.2020YFS0309)the Key Research Institution of Philosophy and Social Sciences in Sichuan Province:Research Center for Yi Culture(Grant No.YZWH 2303)the Key Research Institution of Philosophy and Social Sciences in Sichuan Province:Research Center of National Parks(Grant No.GJGY2023-YB001)。
文摘Remote mountainous villages are at risk of falling back into poverty,despite having been lifted out of extreme poverty.However,there has been a lack of focus on the factors contributing to povertyreturn in these villages,which making it difficult to understand the risks and their underlying causes.This study investigates the spatial distribution of 546 key assistance villages(KAVs)in the Liangshan mountainous region,a former poverty-stricken area,using the average nearest neighbor(ANN)and kernel density estimation(KDE)methods.Linear regression and geographically weighted regression(GWR)models are then employed to analyze the relationship between the KAVs'economy and potential povertyreturning factors.The results show that KAVs are primarily located in elevation ranges of 1800-2500 m(31.87%),with slopes of 6°-15°(42.67%)and 2-3 km from the township(28.94%).The distribution of KAVs exhibits distinct spatial clustering,forming four gathering areas.Several factors impact the KAVs'economy positively,including the normalized difference vegetation index(NDVI),built-up area,grassland,and education facilities,while elevation has a negative effect.The built-up area has the most critical impact on the rural economy,followed by NDVI and elevation.Additionally,education facilities and grassland areas also have significant effects.The study suggests promoting the Ex-situ Poverty Alleviation Relocation Program(ESPARP)and increasing rural built-up areas,grasslands,and educational facilities as practical measures for preventing poverty return and promoting economic development promotion in remote mountain villages.
基金This study was supported by the National Institute of Natural Hazards,Ministry of Emergency Management of China(ZDJ 2021-12)the National Key Research and Development Program of China(2021YFB3901205).
文摘In this study, we used high-resolution optical satellite images on the Google Earth platform to map large-scale landslides in Xianyang City, Shaanxi Province, China. After mapping, a comprehensive and detailed large-scale landslide inventory that contains 2 924 large-scale landslides was obtained. We analyzed the spatial distribu-tion of landslides with seven influencing factors, including elevation, slope angle, aspect, curvature, lithology, distance to a river, and distance to the fault. Landslide Number, Landslide Area, Landslide Number Density(LND), and Landslide Area Percentage(LAP) were selected as indexes for the spatial distribution analysis. The results show that the number and area of landslides in the elevation range of 1 000–1 200 m is the highest. The highest number of landslides was observed in the slope angle of 25°–30°. North-facing slopes are prone to sliding. The area and number of landslides are the largest when the slope curvature ranges from-1.28 to 0. The LND and LAP reach their maxima when the slope curvature is less than-2.56. Areas covered by the Tertiary stratum with weakened fine-grained sandstone and siltstone show the highest LND and LAP values. Regarding distance to a river, the LAP peaks in the range of 300–600 m, whereas the LND peaks in an area larger than 2100 m. The values of LND and LNP rise as the distance from the faults increases, except for the locations 30 km away from active faults. This phenomenon is because active faults in this area pass through the plain areas, while landslides mostly occur in mountainous areas. The cataloging of landslide development in Xianyang City provides a significant scientific foundation for future research on landslides. In addition, the spatial distribution results are useful for landslide hazard prevention decisions and provide valuable references in this area.
基金Sponsored by China Overseas Expertise Introduction Program for Discipline Innovation(D17016)Programme of State of Conservation of Wulingyuan World Natural Heritage Site(2022)。
文摘As an important type of world heritage sites,cultural landscape has always been an important research subject.In order to explore the spatial distribution and evolution mode of cultural landscape all over the world,the paper systematically elaborated the historical context of cultural landscape.The distribution characteristics were analyzed by statistical methods,and the connotation and evolution law represented by cultural landscape in different regions were expounded.The word frequency of regional heritage criteria was analyzed,and the local characteristics of each case were discussed.The research shows that the spatial distribution of global cultural landscape is unbalanced,mainly concentrated in Europe,and the spatial distribution characteristics are closely related to geographical environment,social history,economic development level and many other factors.In terms of inscribed criteria for world heritage sites,most cultural landscapes are mainly based on cultural criteria,but also involve natural criteria.The recognition and protection of cultural landscapes that simultaneously meet multiple criteria will become the focus in the future.
文摘From January 2020 to December 2021,Ulanqab Meteorological Bureau of Inner Mongolia used VLF/LF lightning locator to carry out three-dimensional lightning monitoring in Ulanqab City,and compared with ADTD lightning location data in the same period.The results show that both VLF/LF lightning locator and ADTD lightning locator had excellent monitoring ability for lightning during flood season in Ulanqab.VLF/LF lightning locator was slightly superior to ADTD lightning locator in observation accuracy,the observation ability of low-current cloud-to-ground lightning,intracloud lightning observation and so on.There were obvious temporal and spatial characteristics of cloud-to-ground lightning during flood season in Ulanqab,and there was a certain correlation between the areas where lightning appeared frequently and surface water.Intracloud lightning was mainly concentrated at a height of 1-7 km.Negative cloud-to-ground lightning accounted for about 75%of total cloud-to-ground lightning,and negative intracloud lightning accounted for 39%of total intracloud lightning.
文摘Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical and representative. In this study, the relationship between settlements and topography, rivers and transportation, and the spatial distribution patterns of settlements, such as the aggregation and orientation characteristics of settlements, have been studied. The main conclusions include: 1) The settlement density decreases with the increase of elevation, slope, and distance from rivers and roads;76.25% and 63.17% of the settlements are distributed in the range of elevation 1500 - 3000 m and slope 6° - 25°, the upper reaches of the Min River are mostly alpine valley terrain, the bottom of the river has a low altitude, the landscape is undulating. The warm and humid climate is suitable for farming, conducive to agricultural production, and an ideal living environment for mountain residents. 2) The nuclear density of the settlement is distributed in strips along the axis of the river, and the closer to the river, the greater the nuclear density value. 3) Mathematical statistical methods were applied for the first time to realize the quantitative expression of the coupling of settlement and river direction. The influence of topographic conditions in different watersheds on the coupling degree of settlement extension and river flow direction was revealed. The slope of the fitted straight line between the settlement and river direction was 0.897, and the two directions were consistent. Except for the mainstream of the Min River, the larger values of the standard deviation ellipse flattening of settlements in each basin appeared in the upper reaches of the bay, and the overall trend showed a gradual decrease from the upstream to the downstream, which was consistent with the topographic change characteristics of the basin.
文摘Basic infrastructures and services present an important socio-economic and territorial equity issue, because the availability of these makes it possible to improve the living conditions of populations, makes territories attractive and stimulates their development. The objective of our study has been achieved, so our results provided information on the rate of propagation of basic infrastructures and services, as well as the evolution of the forms of spatial distribution of the latter. The data used comes from the census and geolocation of basic infrastructures and services in the Niakhar area, carried out by the IRD in 2018. Centrographic measurements were used to describe the overall spatial distribution and the use of chi-square statistics confirmed the existence of a preferential direction of distribution. To verify the existence of a spatial structure of infrastructure and service seeding, the Ripley statistic is used. Our results can be useful for land use planning and spatial resource allocation policies. Indeed, the identification of different types of spatial aggregates and the highlighting of the preferred directions of the distribution of basic infrastructures and services, make it possible to correct disparities in the spatial distribution of basic resources.
基金Under the auspices of National Natural Science Foundation of China(No.41271179)。
文摘As cultural facilities,physical bookstore is an important part of urban infrastructure.Influenced by the development of social economy and the internet,physical bookstores also have become a combination of cultural space and tourism experience.In this case,it is necessary to explore the spatial characteristics and influencing factors of physical bookstores.This study uses Density-Based Spatial Clustering of Applications with Noise(DBSCAN),spatial analysis and geographical detectors to calculate the spatial distribution pattern and factors influencing physical bookstores in national central cities/municipality(hereafter using cities)in western China.Based on spatial data,population density,road density and other data,this study constructed a data set of the influencing factors of physical bookstores,consisting of 11 factors along 6 dimensions for 3 national central cities in western China.The results are as follows:first,the spatial distribution pattern of physical bookstores in Xi’an,Chengdu,and Chongqing is unbalanced.The spatial distribution of physical bookstores in Xi’an and Chongqing is from southwest to northeast and are relatively clustered,while those in Chengdu are relatively discrete.Second,the spatial distribution pattern of physical bookstores has been formed under the influence of different factors.The intensity and significance of influencing factors differ in the case cities.However,in general,the social factor,business factor,the density of research facilities,tourism factor and road density are the main driving factors in the three cities.There is a synergistic relationship between public libraries and physical bookstores.Third,the explanatory power becomes stronger after the interaction between various factors.In Xi’an and Chengdu,the density of communities and the density of research facilities have stronger explanatory power for the dependent variable after interacting with other factors.However,in Chongqing,the traffic factors have stronger explanatory power for the dependent variable after interacting with other factors.The results could provide a practical reference for the sustainable development of physical bookstores and encourage a love of reading among the public.
基金This work was financially supported by Zhejiang Provincial Nat-ural Science Foundation of China(No.LR21H280002)a Key Sci-entific and Technological Grant of Zhejiang for Breeding New Agricultural Varieties(No.2021C02074)+1 种基金the Key project of the Central Government:Capacity Building of Sustainable Utilization of Traditional Chinese Medicine Resources(No.2060302)the National Natural Science Foundation of China for State Key Laboratory(No.81973415).
文摘Salvia miltiorrhiza and S.grandifolia are rich in diterpenoids and have therapeutic effects on cardiovascular diseases.In this study,the spatial distribution of diterpenoids in both species was analyzed by a combination of metabolomics and mass spectrometry imaging techniques.The results indicated that diterpenoids in S.miltiorrhiza were mainly abietane-type norditerpenoid quinones with a furan or dihydrofuran D-ring and were mainly distributed in the periderm of the roots,e.g.cryptotanshinone and tanshinone IIA.The compounds in S.grandifolia were mainly phenolic abietane-type tricyclic diterpenoids with six-or seven-membered C-rings,and were widely distributed in the periderm,phloem,and xylem of the roots,e.g.11-hydroxy-sugiol,11,20-dihydroxy-sugiol,and 11,20-dihydroxy-ferruginol.In addition,the leaves of S.grandifolia were rich in tanshinone biosynthesis precursors,such as 11-hydroxy-sugiol,while those of S.miltiorrhiza were rich in phenolic acids.Genes in the upstream pathway of tanshinone biosynthesis were highly expressed in the root of S.grandifolia,and genes in the downstream pathway were highly expressed in the root of S.miltiorrhiza.Here,we describe the specific tissue distributions and mechanisms of diterpenoids in two Salvia species,which will facilitate further investigations of the biosynthesis of diterpenoids in plant synthetic biology.
基金supported by The Special Foundation for National Science and Technology Basic Resources Investigation of China(2019FY202300)the Biodiversity Investigation,Observation and Assessment Program of Ministry of Ecology and Environment of China(2110404).
文摘Growing public awareness of the importance of protecting biodiversity requires the development of forest practices that increase the complexity of stand structure.Understanding the ecological processes of different forest vegetation provide insights into community coexistence mechanisms.In this paper,the spatial patterns of three different communities,evergreen broadleaf forest,deciduous broadleaf forest,and mixed needleleaf and broadleaf forest at Mt.Huangshan,China,were quantified with four structural parameters,the mingling index,the uniform angle index,the diameter dominance index and the crowdedness index.All trees with a diameter at breast height of more than 5 cm were measured.Our analyses highlighted that most trees in the three communities were extremely dense and slightly clumped,with a moderate size differentiation and high mixed structure.In mixed needleleaf and broadleaf forest,the distribution pattern of tree species was better than the other two forests.Overall,spatial patterns in mixed needleleaf and broadleaf forest exhibited a strong stability-effect,that is,the stand had a suitable environment for the stable survival of the forest.With the increasing of elevation,the degree of the mingling index and the crowdedness index increased,however,there was no influence on the uniform angle index and the diameter dominance index.Further,at the same elevation,four structural parameters of shady slope were larger than that of sunny slope.Then we found the relationship between stand spatial structure and environment factors had important influence on forest structure.Our work contributes to the knowledge of population structure,and further provide theoretical basis for the sustainable development of forest resources and protecting biodiversity of Huangshan Mountain.In future studies,it is necessary to explore the limiting factors of community spatial distribution by combining species diversity and functional traits.
基金Under the auspices of the Foundation of the Education Department of Jilin Province,China(No.JJKH20211290KJ)National Natural Science Foundation of China(No.42171198)。
文摘Village classification is the first step to implementing China’s rural revitalization(RR)strategy,and understanding the geographic differences in the distribution of village types helps to grasp the pathway of their unique development.This study spatialized9250 villages in Jilin Province(divided into six types)of China,and their distribution characteristics and influencing factors were examined using methods such as kernel density estimation,Ripley’s K function,the co-location quotient,and Geodetector.The results indicate that the spatial distribution balance and density of village types are different.All types of villages show an agglomeration distribution pattern,but the scale and intensity vary.There is a strong spatial association between agglomerative promotion(AP)and stable improvement(SIm)villages,as well as between characteristic protection(CP)and prospering frontier and enriching people(PE)villages.The factors affecting their distribution include terrain undulation,the percentage of arable land,the distance to the county town,road network density,population density,gross domestic product(GDP),and industrial enterprise density.The influencing factors for the distribution of village types are closely related to the function of each village.Based on the differences in the spatial distribution and influencing factors of different village types,policy suggestions are given for classified development.
基金Supported by the Special Scientific Research Fund of Agriculture Public Welfare Profession of China(No.201303056)the State Key Laboratory of Freshwater Ecology and Biotechnology(No.2011FBZ28)the Science and Technology Research Project of China Three Gorges Corporation(No.CT-12-08-01)
文摘We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang(Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns dif fered in the two lakes and were af fected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish >45 cm(smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes.
基金supported by the National Natural Science Foundation of China(Grant No.11822203and 11702026)。
文摘Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.
基金Under the auspices of the National Natural Science Foundation of China(No.41871101)the Science and Technology Development Project of Jilin Province(No.20190201115JC)the‘Strategic Priority Research Program’of the Chinese Academy of Sciences(No.XDA23060402)。
文摘Carex tussock plays an important role in supporting biodiversity and carbon sequestration of wetland ecosystems,while it is highly threatened by climate change and anthropogenic activities.Therefore,identifying the potential distribution patterns of Carex tussocks wetland is vital for their targeted conservation and restoration.The current and future(2050s and 2070s)potential habitats distribution of Carex tussocks in Northeast China were predicted using a Maximum Entropy(Maxent)model based on 68 current data of Carex tussock distributions and three groups of environmental variables(bioclimate,topography,soil properties).Results show that isothermality,seasonal precipitation variability and altitude are important factors that determine the distribution of Carex tussock.The high suitable habitat of Carex tussock is about 5.7×10^(4)km^(2) and mainly distributed in the Sanjiang Plain,Songnen Plain,Changbai Mountains and Da Hinggan Mountains.The area of stable habitats of Carex tussock is significantly higher than the lost and expanded habitats in the future climate scenarios,and the unsuitable habitats mainly occur in Da Hinggan Mountains,Xiao Hinggan Mountains and Changbai Mountains.Overall,Carex tussock wetlands at high altitude and high latitude are more sensitive to climate change,and more attention should be invested in high latitude and high altitude areas.
基金Sponsored by Science Foundation for Young Scholars of Hunan Agricultural University(14QN25)
文摘By using geography quantitative methods and Arc GIS,the spatial distribution characteristics,types,rules and influencing factors of 20 representative rural tourism attractions in Yangzhou City were analyzed.The results show that the traffic accessibility of various regions in Yangzhou City correlated positively with the spacial distribution of rural tourist attractions in quantity in these regions.The rural tourist attractions were dense in regions 10-20 km away from the center of the city;there was only one rural tourist attraction in regions 40-70 km away from the center of the city;some big rural tourist attractions were distributed in regions 70-90 km away from the center of the city;market orientation influenced the spatial distribution of the rural tourist attractions obviously.In regions 0-30 km away from the center of the city,most rural tourist attractions mainly provided recreation and entertainment services for tourists;in regions more than 70 km away from the center of the city,most rural tourist attractions mainly provided health and recuperation services for tourists;in regions 30-50 km away from the center of the city,the service functions of the rural tourist attractions were compound and diversified.
基金Under the auspices of National Natural Science Foundation of China(No.42171193,41871177)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.22lgqb13)Guangzhou Science and Technology Project(No.202102080254)。
文摘China is vigorously implementing a rural revitalization strategy with the prosperity of rural industries as the primary goal.The characteristic economy of’One Village One Product’(OVOP)is particularly significant in promoting rural revitalization and increasing farmers’income.Accurately identifying the spatial distribution characteristics and influencing factors of agricultural specialized villages(ASVs)under OVOP provides a preliminary research basis for constructing the theoretical framework of specialization and clustering of rural industrial development.This study takes Guangdong Province,China as an example,using kernel density estimation,Ripley’s K function,geometric fractals,principal component regression and other methods to identify the spatial distribution characteristics and influencing factors of ASVs.It was found that the ASVs in Guangdong Province are dominated by the planting industry,with an uneven number in space and a multi patch distribution.Specifically,ASVs are mainly distributed in the Chaoshan Plain in the eastern Guangdong,the northern mountainous area of Guangzhou,and the eastern part of Maoming City.Its spatial distribution mode obeys the aggregation distribution pattern at the scale of province,region and municipality(prefecture-level city).In addition,the formation and development of ASVs are affected by multiple internal and external factors.The influence of basic factors such as natural environmental conditions is gradually weakening,while the influence of social and economic factors such as market demand is gradually increasing.This study can enrich the research results of ASVs and provide guidance and reference for the long-term and high-quality development of rural industry revitalization.
