Sedimentary Characteristics,Ages,and Environmental Significance of Gravel Deposits and Loess in Shandong,Eastern China:Regional Response to Global Change Since the Last Glacial Period

Investigation of rarely studied gravel layers found in the loess in Shandong Province,eastern China,reveals the fabric characteristics of two gravel layers(G1,G2)and the sedimentary characteristics of loess at the typical and well-preserved Heiyu section(HY),where,to determine the paleoclimatic changes during Marine Isotope Stage 3a.Optically stimulated luminescence dates of the HY formation range from 0.26±0.02 ka to 39.00±2.00 ka.In addition,the ages of G1 and G2 were estimated using the Bayesian model to be 39.60-40.50 and 29.00-29.50 ka.G1 and G2 are mainly composed of fine and medium gravel,both of which were subangular to subrounded limestone,with gravel directions to NE and E.The average flow velocity,average depth,and flood peak flow of G1 are 1.10 m/s,0.49 m,and 37.04 m^(3)/s,respectively,calculated using the flow energy method,whereas those of G2 are 0.98 m/s,0.38 m,and 18.38 m^(3)/s,respectively.Analysis of climate proxy indices show that the sedimentary environment of the gravel and loess in HY might be a regional response to global change.

Effects of extreme soil water stress on photosynthetic efficiency and water consumption characteristics of Tamarix chinensis in China's Yellow River Delta

Soil moisture is a major limiting factor for plant growth on shell ridge islands in the Yellow River Delta.However, it is difficult to carry out situ experiment to study dominant plant photosynthesis physiological on the shell ridge islands under extreme soil water stress. To evaluate the adaptability of plants to light and moisture variations under extreme soil moisture conditions present on these islands, we measured photosynthetic gas exchange process,chlorophyll fluorescence, and stem sap flow variables for3-year-old trees of Tamarix chinensis Lour, a restoration species on these islands, subjected to three types of soilwater levels: waterlogging stress(WS), alternating dry–wet(WD), and severe drought stress(SS) to inform decisions on its planting and management on shell ridge islands. Gas exchange, chlorophyll fluorescence, and stem sap flow in T.chinensis were then measured. Net photosynthetic rate(PN), transpiration rate(E), and water use efficiency(WUE)were similar under WS and alternating dry–wet conditions,but their mean E and WUEdiffered significantly(P \ 0.05).Under SS, the PN, E and WUEof T. chinensis leaves varied slightly, and mean PN, E and WUEwere all low. Apparent quantum efficiency(AQY), light compensation point(LCP),light saturation point(LSP), and maximum net photosynthetic rate(PNmax) of leaves were not significantly different(P [ 0.05) under WS and dry–wet conditions; however,under extreme drought stress, compared with the dry–wet conditions, LCPwas higher, LSPwas lower, and AQYand PNmaxwere both at the lowest level. Therefore, drought stress weakened light adaptability of leaves, and the efficiency of light transformation was poorer.(3) Maximum photochemical efficiency(Fv/Fm) and the actual photochemical efficiency(UPSII) were similar under waterlogged stress and dry–wet conditions, indicating a similar healthy photosynthetic apparatus and photosynthetic reaction center activity, respectively. Under SS, Fv/Fmwas 0.631, and the coefficient of non-photochemical quenching(NPQ) was0.814, which indicated that while the photosynthetic mechanism was damaged, the absorbed light energy was mainly dissipated in the form of heat, and the potential photosynthetic productivity was significantly reduced. The daily cumulants of sap flow of T. chinensis under dry–wet alternation and severe drought stress were 22.25 and63.97% higher, respectively, than under waterlogging stress. Daily changes in sap flow velocity for T. chinensis differed under the three soil water levels. Stem sap flow was weak at night under severe drought stress. Under dry–wet alternation, daytime average stem sap flow velocity was the highest, and night stem flow accounted for 10.26%of the day cumulants, while under waterlogged stress, the average nightly stem flow velocity was the highest,accounting for 31.82% of the day cumulants. These results provide important information for regional vegetation restoration and ecological reconstruction.

Effects of soil drought stress on photosynthetic gas exchange traits and chlorophyll fluorescence in Forsythia suspensa

To clarify the changes in plant photosynthesis and mechanisms underlying those responses to gradually increasing soil drought stress and reveal quantitative relationships between photosynthesis and soil moisture,soil water conditions were controlled in greenhouse pot experiments using 2-year-old seedlings of Forsythia suspensa(Thunb.) Vahl. Photosynthetic gas exchange and chlorophyll fluorescence variables were measured and analyzed under 13 gradients of soil water content. Net photosynthetic rate(PN), stomatal conductance(gs), and water-use efficiency(WUE) in the seedlings exhibited a clear threshold response to the relative soil water content(RSWC). The highest PNand WUEoccurred at RSWCof51.84 and 64.10%, respectively. Both PNand WUEwere higher than the average levels at 39.79% B RSWCB 73.04%. When RSWCdecreased from 51.84 to 37.52%,PN, gs, and the intercellular CO2 concentration(Ci)markedly decreased with increasing drought stress; the corresponding stomatal limitation(Ls) substantially increased, and nonphotochemical quenching(NPQ) also tended to increase, indicating that within this range of soil water content, excessive excitation energy was dispersed from photosystem II(PSII) in the form of heat, and the reduction in PNwas primarily due to stomatal limitation.While RSWCdecreased below 37.52%, there were significant decreases in the maximal quantum yield of PSII photochemistry(Fv/Fm) and the effective quantum yield of PSII photochemistry(UPSII), photochemical quenching(qP), and NPQ; in contrast, minimal fluorescence yield of the dark-adapted state(F0) increased markedly. Thus,the major limiting factor for the PNreduction changed to a nonstomatal limitation due to PSII damage. Therefore, an RSWCof 37.52% is the maximum allowable water deficit for the normal growth of seedlings of F. suspensa, and a water content lower than this level should be avoided in field soil water management. Water contents should be maintained in the range of 39.79% B RSWCB 73.04% to ensure normal function of the photosynthetic apparatus and high levels of photosynthesis and efficiency in F.suspensa.

Interpreting sedimentation dynamics at Longxi catchment in the Three Gorges Area,China,using Cs-137 activity,particle size and rainfall erosivity

Reservoir sedimentation dynamics were interpreted using Cs-137 activity,particle size and rainfall erosivity analysis in conjunction with sediment profile coring.Two sediment cores were retrieved from the Changshou reservoir of Chongqing,which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an acrylic tube with an inner diameter of 6 cm.The extracted cores were sectioned at 2 cm intervals.All sediment core samples were dried,sieved(<2 mm) and weighed.137 Cs activity was measured by γ-ray spectrometry.The particle size of the core samples was measured using laser particlesize granulometry.Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends.The peak fallout of 137 Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B.The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982,1989,1998 and 2005,respectively.Sedimentation rates were calculated according to the sediment profile chronological controls of 1956,1963,1982,1989,1998 and 2005.The highest sedimentation rate was around 2.0 cm?a^(-1) between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented,leading to accelerated soil erosion in the Longxi catchment.Since 1990 s,andparticularly since 2005,sedimentation rates clearly decreased,since a number of soil conservation programs have been carried out in the catchment.The combined use of 137 Cs chronology,particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration.Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.

Magmatism-Related Thermal Simulation of Volcanic Arcs in the Molucca Sea Bidirectional Subduction System

The bidirectional subduction system,island arc magmatic activities,and thermal structure of the forearc basin in the Molucca Sea are taken into consideration in this study.The active volcanic arcs on both sides of the bidirectional subduction zone in the Molucca Sea are undergoing arc-arc collisions.We applied a finite element thermal simulation method to reconstruct the thermal evolution history of the Molucca Sea Plate based on geophysical data.Then,we analyzed the thermodynamic characteristics of island arc volcanism on both sides of the bidirectional subduction zone.The results showed that at 10Myr,the oceanic ridge of the Molucca Sea Plate was asymmetrically biased to the west,causing this bidirectional subduction to be deeper in the west than in the east.Furthermore,the oceanic ridge subducted under the Sangihe arc at 5.5Myr,causing intermittent cessation of volcanic activities.Due to the convergence of bidirectional subduction,the geothermal gradient in the top 3km depth of the forearc area between the Sangihe and Halmahera arcs decreased from about 60℃km^(−1) at 4Myr to about 38℃km^(−1) today.Finally,within the 45–100 km depth range of the sliding surface of the subduction,anomalously high-temperature zones formed due to shear friction during the bidirectional subduction.

Urban expansion and intra-urban land evolution as well as their natural environmental constraints in arid/semiarid regions of China from 2000–2018

Rapid urbanization has occurred in arid/semiarid China,threatening the sustainability of fragile dryland ecosystems;however,our knowledge of natural environmental constraints on multiscale urban lands in this region is still lacking.To solve this issue,this study retrieved 15-m multiscale urban lands.Results indicated that urban area increased by 68%during 2000–2018,and one-third of the increase was contributed by only three large cities.The coverage of impervious surface area(ISA) and vegetated area(VA) increased by 16.6%and 1.38%,respectively.Such land-cover change may be helpful in suppressing wind erosion and sand storms.We also found that the newly urban lands had relatively lower ISA and higher VA than the old urban lands,indicating an improved human settlement environment.Strong environmental constraints on urban expansion were identified,with cities in oasis urban environments(OUEs) that had water supply expanding 150% faster than cities in desert urban environments(DUEs).Urban development was also constrained by terrain,with 73% of the ISA expansion occurring in relatively flat areas.Overall,the aggregated pattern of urbanization and the increase in ISA and VA in the newly urbanized lands have improved water-use efficiency and ecological services and benefited desert ecosystem protection in arid/semiarid China.

Diverse Climatic and Anthropogenic Impacts on Desertification in the Middle Reaches of Yarlung Zangbo River Catchment on the Tibetan Plateau

The unique desertification processes occurring under the Alpine climate and ecosystem on the Tibetan Plateau could provide critical clues to the natural and anthropogenic impacts on desertification.This study used the Landsat data to investigate the spatial and temporal distribution of desertification from 1990 to 2020 in two areas(Shannan and Mainling),within the Yarlung Zangbo River Basin.The results show not only distinct spatial patterns but also various temporal changes of desertification.In Shannan,aeolian sand was distributed over wide areas from valley floor to mountain slope,while in Mainling,it is distributed sporadically at the footslope.The aeolian sandy land initially expanded before undergoing long-term shrinkage in Shannan.While in Mainling,it steadily expanded followed by a rapid decrease.These changes are attributed to both climate change and human activites.The increase in temperature causes desertification expansion in Shannan,while favorable climate conditions coupled with decreasing human activity promoted desertification reversal.However,both the expansion and shrinkage of desertification were sensitive to human activity in Mainling.This highlights the diverse responses of desertification to natural and anthropogenic impacts on different backgrounds of climatic and vegetation coverage.A threshold of climatic conditions may control the dominance factors in desertification,shifting from natural to anthropogenic elements.

Black Locust Transpiration Responses to Soil Water Availability as Affected by Meteorological Factors and Soil Texture

On the Loess Plateau of China, a dry soil layer may form due to excess transpiration, leading to degradation of black locust(Robinia pseudoacacia) stands. In order to better manage projects involving black locust, this study was intended to investigate the response of black locust transpiration rate to soil water availability as affected by meteorological factors using two representative soils(loamy clay and sandy loam) on the Loess Plateau. Four soil water contents were maintained for black locust seedlings grown in pots initially outdoors and then in a climate-controlled chamber, by either drying or irrigating the pots. In both environments, daily transpiration rates were related by a power function to air temperature and by a logistic function to reference evapotranspiration(ET0). Transpiration rates were more susceptible to changes in the meteorological conditions in the sandy loam than in the loamy clay soil. The transpiration rate in the well-watered treatment was greater for black locust grown in the sandy loam than in the loamy clay soil. Normalized transpiration rates were unaffected by ET0 until a critical value of soil water content(θc) was attained; the θc value decreased significantly for the loamy clay soil but increased significantly for the sandy loam soil when ET0 increased. These suggested that the effect of the meteorological condition on the transpiration characteristics of black locust was dependent on soil texture.

Electrical properties of dry polycrystalline olivine mixed with various chromite contents: Implications for the high conductivity anomalies in subduction zones

Chromite,a crucial high-conductivity mineral phase of peridotite in ophiolite suites,has a significant effect on the electrical structure of subduction zones.The electrical conductivities of sintered polycrystalline olivine containing various volume percents of chromite(0,4,7,10,13,16,18,21,23,100 vol.%)were measured using a complex impedance spectroscopic technique in the frequency range of 10^(−1)-10^(6) Hz under the conditions of 1.0-3.0 GPa and 873-1223 K.The relationship between the conductivities of the chromite-bearing olivine aggregates and temperatures conformed to the Arrhenius equation.The positive effect of pressure on the conductivities of the olivine-chromite systems was much weaker than that of temperature.The chromite content had an important effect on the conductivities of the olivine-chromite systems,and the bulk conductivities increased with increasing volume fraction of chromite to a certain extent.The inclusion of 16 vol.%chromites dramatically enhanced the bulk conductivity,implying that the percolation threshold of interconnectivity of chromite in the olivine-chromite systems is-16 vol.%.The fitted activation enthalpies for pure polycrystalline olivine,polycrystalline olivine with isolated chromite,polycrystalline olivine with interconnected chromites,and pure polycrystalline chromite were 1.25,0.78-0.87,0.48-0.54,and 0.47 eV,respectively.Based on the chemical compositions and activation enthalpies,small polaron conduction was proposed to be the dominant conduction mechanism for polycrystalline olivine with various chromite contents.Furthermore,the conductivities of polycrystalline olivine with interconnected chromite(10-1.5-100.5 S/m)provides a reasonable explanation for the high conductivity anomalies in subduction-related tectonic environments.

Industrial land expansion in rural China threatens environmental securities

China’s rural industrialization has been a major driver for its rapid economic growth during the recent decades,but its myriad environmental risks are yet to be fully understood.Based on a comprehensive national land-use data set,our study shows that the area of China’s rural industrial land(RIL)quadrupled during 1990–2015,reaching 39338 km2 in 2015,comparable to urbanization in magnitude but with a much greater degree of landscape fragmentation which implies stronger ecological and environmental impacts.About 91%of the protected areas in the central China were within 50 km from rural industrial land,thus exposed to industrial disturbances.Accelerated rural industrial land expansion,particularly in regions under high geo-hazard risks,led to dramatically increased environmental risks,threatening the safety and health of both rural industrial workers and residents.Moreover,negative effects from rural industrial land expansion could partially offset the crop production growth in recent decades.The underprivileged rural population in the west bears a disproportionally large share of the increased environmental risks.China urgently needs to design and implement sustainable policies to restrict and reshape its rural industrialization.This study aims to inspire policy makers and researchers to rethink the current model of industrial expansion and improve rural industrial land planning,which is important for achieving the sustainable development goals of China.

Fungal diversity notes 1512–1610: taxonomic and phylogenetic contributions on genera and species of fungal taxa

This article is the 14th in the Fungal Diversity Notes series,wherein we report 98 taxa distributed in two phyla,seven classes,26 orders and 50 families which are described and illustrated.Taxa in this study were collected from Australia,Brazil,Burkina Faso,Chile,China,Cyprus,Egypt,France,French Guiana,India,Indonesia,Italy,Laos,Mexico,Russia,Sri Lanka,Thailand,and Vietnam.There are 59 new taxa,39 new hosts and new geographical distributions with one new combination.The 59 new species comprise Angustimassarina kunmingense,Asterina lopi,Asterina brigadeirensis,Bartalinia bidenticola,Bartalinia caryotae,Buellia pruinocalcarea,Coltricia insularis,Colletotrichum fexuosum,Colletotrichum thasutense,Coniochaeta caraganae,Coniothyrium yuccicola,Dematipyriforma aquatic,Dematipyriforma globispora,Dematipyriforma nilotica,Distoseptispora bambusicola,Fulvifomes jawadhuvensis,Fulvifomes malaiyanurensis,Fulvifomes thiruvannamalaiensis,Fusarium purpurea,Gerronema atrovirens,Gerronema favum,Gerronema keralense,Gerronema kuruvense,Grammothele taiwanensis,Hongkongmyces changchunensis,Hypoxylon inaequale,Kirschsteiniothelia acutisporum,Kirschsteiniothelia crustaceum,Kirschsteiniothelia extensum,Kirschsteiniothelia septemseptatum,Kirschsteiniothelia spatiosum,Lecanora immersocalcarea,Lepiota subthailandica,Lindgomyces guizhouensis,Marthe asmius pallidoaurantiacus,Marasmius tangerinus,Neovaginatispora mangiferae,Pararamichloridium aquisubtropicum,Pestalotiopsis piraubensis,Phacidium chinaum,Phaeoisaria goiasensis,Phaeoseptum thailandicum,Pleurothecium aquisubtropicum,Pseudocercospora vernoniae,Pyrenophora verruculosa,Rhachomyces cruralis,Rhachomyces hyperommae,Rhachomyces magrinii,Rhachomyces platyprosophi,Rhizomarasmius cunninghamietorum,Skeletocutis cangshanensis,Skeletocutis subchrysella,Sporisorium anadelphiae-leptocomae,Tetraploa dashaoensis,Tomentella exiguelata,Tomentella fuscoaraneosa,Tricholomopsis lechatii,Vaginatispora favispora and Wetmoreana blastidiocalcarea.The new combination is Torula sundara.The 39 new records on hosts and geographical distribution comprise Apiospora guiyangensis,Aplosporella artocarpi,Ascochyta medicaginicola,Astrocystis bambusicola,Athelia rolfsii,Bambusicola bambusae,Bipolaris luttrellii,Botryosphaeria dothidea,Chlorophyllum squamulosum,Colletotrichum aeschynomenes,Colletotrichum pandanicola,Coprinopsis cinerea,Corylicola italica,Curvularia alcornii,Curvularia senegalensis,Diaporthe foeniculina,Diaporthe longicolla,Diaporthe phaseolorum,Diatrypella quercina,Fusarium brachygibbosum,Helicoma aquaticum,Lepiota metulispora,Lepiota pongduadensis,Lepiota subvenenata,Melanconiella meridionalis,Monotosporella erecta,Nodulosphaeria digitalis,Palmiascoma gregariascomum,Periconia byssoides,Periconia cortaderiae,Pleopunctum ellipsoideum,Psilocybe keralensis,Scedosporium apiospermum,Scedosporium dehoogii,Scedosporium marina,Spegazzinia deightonii,Torula fci,Wiesneriomyces laurinus and Xylaria venosula.All these taxa are supported by morphological and multigene phylogenetic analyses.This article allows the researchers to publish fungal collections which areimportant for future studies.An updated,accurate and timely report of fungus-host and fungus-geography is important.We also provide an updated list of fungal taxa published in the previous fungal diversity notes.In this list,erroneous taxa and synonyms are marked and corrected accordingly.

Responses of soil microbial communities to freeze–thaw cycles in a Chinese temperate forest

Background:Freeze–thaw events are common in boreal and temperate forest ecosystems and are increasingly infuenced by climate warming.Soil microorganisms play an important role in maintaining ecosystem stability,but their responses to freeze–thaw cycles(FTCs)are poorly understood.We conducted a feld freeze–thaw experiment in a natural Korean pine and broadleaf mixed forest in the Changbai Mountain Nature Reserve,China,to determine the dynamic responses of soil microbial communities to FTCs.Results:Bacteria were more sensitive than fungi to FTCs.Fungal biomass,diversity and community composition were not signifcantly afected by freeze–thaw regardless of the stage.Moderate initial freeze–thaw resulted in increased bacterial biomass,diversity,and copiotrophic taxa abundance.Subsequent FTCs reduced the bacterial biomass and diversity.Compared with the initial FTC,subsequent FTCs exerted an opposite efect on the direction of change in the composition and function of the bacterial community.Soil water content,dissolved organic carbon,ammonium nitrogen,and total dissolved phosphorus were important factors determining bacterial community diversity and composition during FTCs.Moreover,the functional potentials of the microbial community involved in C and N cycling were also afected by FTCs.Conclusions:Diferent stages of FTCs have diferent ecological efects on the soil environment and microbial activities.Soil FTCs changed the soil nutrients and water availability and then mainly infuenced bacterial community composition,diversity,and functional potentials,which may disturb C and N states in this temperate forest soil.This study also improves our understanding of microbial communities regulating their ecological functions in response to climate change.

Devonian-Carboniferous Pillow OIB-Type Basalts in the Youjiang Basin,SW China:Implications for the Eastern Extension of the Paleo-Tethys Branch Ocean

Late Paleozoic pillow basalts are well preserved in the Youjiang Basin of SW China.In this study,we conducted geochemical and Sr-Nd isotopic study on the Late Devonian and Late Carboniferous basalts in Napo area,Youjiang Basin.The analyzed samples comprise moderate SiO2,TiO2,Mg#,and REE contents,with slightly positive or negative Eu anomalies,similar to the chemical nature of OIB(Oceanic island basalt).All basalts show low(^(143)Nd/^(144)Nd)iand(^(87)Sr/^(86)Sr)ivalues,close to EMI-type(I-type Enriched Mantle)magma source.Late Carboniferous basalts display higher(^(87)Sr/^(86)Sr)i,Nb/Th,and lowerε_(Nd)(t),Zr/Nb values than those of the Late Devonian basalts,implying progressively decreased enrichment components in the magma source processes.Such evolution trend reflects a continuous lithospheric thinning event,supporting a progressive rifting setting of the Youjiang Basin along the southwestern margin of the Yangtze Block in Late Paleozoic.Combined with regional geological background,the Youjiang Basin is viewed as a continental rift basin related to the opening of the Paleo-Tethys Ocean in Late Devonian and became a passive continental margin basin in Carboniferous.The Paleo-Tethys branch ocean probably extended further to the southern Youjiang Basin,likely corresponding to the Song Ma suture zone.

Spectral clustering eigenvector selection of hyperspectral image based on the coincidence degree of data distribution

Spectral clustering is a well-regarded subspace clustering algorithm that exhibits outstanding performance in hyperspectral image classification through eigenvalue decomposition of the Laplacian matrix.However,its classification accuracy is severely limited by the selected eigenvectors,and the commonly used eigenvectors not only fail to guarantee the inclusion of detailed discriminative information,but also have high computational complexity.To address these challenges,we proposed an intuitive eigenvector selection method based on the coincidence degree of data distribution(CDES).First,the clustering result of improved k-means,which can well reflect the spatial distribution of various types was used as the reference map.Then,the adjusted Rand index and adjusted mutual information were calculated to assess the data distribution consistency between each eigenvector and the reference map.Finally,the eigenvectors with high coincidence degrees were selected for clustering.A case study on hyperspectral mineral mapping demonstrated that the mapping accuracies of CDES are approximately 56.3%,15.5%,and 10.5%higher than those of the commonly used top,high entropy,and high relevance eigenvectors,and CDES can save more than 99%of the eigenvector selection time.Especially,due to the unsupervised nature of k-means,CDES provides a novel solution for autonomous feature selection of hyperspectral images.

Changes in global land surface frozen ground and freeze-thaw processes during 1950-2020 based on ERA5-Land data

Frozen ground(FG)plays an important role in global and regional climates and environments through changes in land freeze-thaw processes,which have been conducted mainly in different regions.However,the changes in land surface freeze-thaw processes under climate change on a global scale are still unclear.Based on ERA5-Land hourly land skin temperature data,this study evaluated changes in the global FG area,global land surface first freeze date(FFD),last freeze date(LFD)and frost-free period(FFP)from 1950 to 2020.The results show that the current FG areas(1991-2020 mean)in the Northern Hemisphere(NH),Southern Hemisphere(SH),and globe are 68.50×10^(6),9.03×10^(6),and 77.53×10^(6)km^(2),which account for 72.4%,26.8%,and 60.4%of the exposed land(excluding glaciers,ice sheets,and water bodies)in the NH,SH and the globe,respectively;further,relative to 1951-1980,the FG area decreased by 1.9%,8.8%,and 2.8%,respectively.Seasonally FG at lower latitudes degrades to intermittently FG,and intermittently FG degrades to non-frozen ground,which caused the global FG boundary to retreat to higher latitudes from 1950 to 2020.The annual FG areas in the NH,SH,and globe all show significant decreasing trends(p<0.05)from 1950 to 2020 at-0.32×10^(6),-0.22×10^(6),and-0.54×10^(6)km^(2)per decade,respectively.The FFP prolongation in the NH is mainly influenced by LFD advance,while in the SH it is mainly controlled by FFD delay.The prolongation trend of FFP in the NH(1.34 d per decade)is larger than that in the SH(1.15 d per decade).

区域多维发展综合测度方法及应用（英文）

National and international research on regional development has matured from the use of single elements and indicators to the application of comprehensive multi-element and multi-indicator measures.We selected 12 indicators from six dimensions for analysis in this study,including income,consumption,education,population urbanization,traffic,and indoor living facilities.We then proposed the polyhedron method to comprehensively measure levels of regional multidimensional development.We also enhanced the polygon and vector sum methods to render them more suitable for studying the status of regional multidimensional development.Finally,we measured levels of regional multidimensional development at county,city,and provincial scales across China and analyzed spatial differences using the three methods above and the weighted sum method applied widely.The results of this study reveal the presence of remarkable regional differences at the county scale across China in terms of single and multidimensional levels of regional development.Analyses show that values of the regional multidimensional development index(RMDI)are high in eastern coastal areas,intermediate in the midlands and in northern border regions,and low in the southwest and in western border regions.Districts characterized by enhanced and the highest levels of this index are distributed in eastern coastal areas,including cities in central and western regions,as well as areas characterized by the development of energy and mineral resources.The regional distribution of reduced and the lowest levels of this index is consistent with concentrations of areas that have always been impoverished.Correlation analyses of the results generated by the four methods at provincial,city,and county scales show that all are equivalent in practical application and can be used to generate satisfactory measures for regional multidimensional development.Additional correlation analyses between RMDI values calculated using the polyhedron method and per capita gross domestic product(GDP)demonstrate that the latter is not a meaningful proxy for the level of regional multidimensional development.