The unimodal latitudinal pattern of K,Ca and Mg concentration and its potential drivers in forest foliage in eastern China

Potassium(K),calcium(Ca),and magnesium(Mg)are essential elements with important physiological functions in plants.Previous studies showed that leaf K,Ca,and Mg concentrations generally increase with increasing latitudes.However,recent meta-analyses suggested the possibility of a unimodal pattern in the concentrations of these elements along latitudinal gradients.The authenticity of this unimodal latitudinal pattern,however,requires validation through large-scale field experimental data,and exploration of the underlying mechanisms if the pattern is confirmed.Here,we collected leaves of common species of woody plants from 19 montane forests in the north-south transect of eastern China,including 322 species from 160 genera,67 families;and then determined leaf K,Ca,and Mg concentrations to explore their latitudinal patterns and driving mechanisms.Our results support unimodal latitudinal patterns for all three elements in woody plants across eastern China,with peak values at latitude 36.5±1.0°N.The shift of plant-functional-type compositions from evergreen broadleaves to deciduous broadleaves and to conifers along this latitudinal span was the key factor contributing to these patterns.Climatic factors,mainly temperature,and to a lesser extent solar radiation and precipitation,were the main environmental drivers.These factors,by altering the composition of plant communities and regulating plant physiological activities,influence the latitudinal patterns of plant nutrient concentrations.Our findings also suggest that high leaf K,Ca,and Mg concentrations may represent an adaptive strategy for plants to withstand water stress,which might be used to predict plant nutrient responses to climate changes at large scales,and broaden the understanding of biogeochemical cycling of K,Ca,and Mg.

Strong evidence for latitudinal diversity gradient in mosses across the world

Species richness generally decreases with increasing latitude,a biodiversity gradient that has long been considered as one of the few laws in ecology.This latitudinal diversity gradient has been observed in many major groups of organisms.In plants,the latitudinal diversity gradient has been observed in vascular plants,angiosperms,ferns,and liverworts.However,a conspicuous latitudinal diversity gradient in mosses at a global or continental scale has not been observed until now.Here,we analyze a comprehensive data set including moss species in each band of 20° in latitude worldwide.Our results show that moss species richness decreases strongly with increasing latitude,regardless of whether the globe is considered as a whole or different longitudinal segments(e.g.,Old World versus New World) are considered separately.This result holds when variation in area size among latitudinal bands is taken into account.Pearson's correlation coefficient between latitude and species richness is-0.99 for both the Northern and Southern Hemispheres.Because bryophytes are an extant lineage of early land plants and because mosses not only include most of extant species of bryophytes but also are important constituents of most terrestrial ecosystems,understanding geographic patterns of mosses is particularly important The finding of our study fills a critical knowledge gap.

Modelling,Validation,and Calculations of Stratospheric Ozone Dynamics and Latitudinal Changes

This paper presents an engineering system approach of 2-D cylindrical model of mass balance calculations with convection,diffusion,and all potential photolysis,ozone generating and depleting chemical reactions considered.This model was developed,validated,and tested under different conditions for the stratospheric ozone.The calculated ozone concentrations and profile in the stratosphere at both the Equator and mid-latitudinal location of 40°S were found to exhibit a similar and close profile and peak value of the published measured data.The discrepancy between the calculations and measurements for the average ozone concentration was shown to be less than 1%and the variation of distributions to be less than 19%.The latitudinal changes of ozone concentrations,distribution,and peak of the layer were found to shift from 9.41 ppm at mid-altitude of z=30 km at the Equator,to 7.81 ppm at z=34.5 km at 40°S,to 5.78 ppm at higher altitude z=39 km at the South Pole.The total ozone abundances at strategic latitudes at 0°S,20°S,40°S,60°S,and 90°S,were found to remain stable and not much changed,from 305 DU to 335 DU,except a smaller value of 288 DU at the South Pole.The possible explanations of ozone profile change and peak shifting as affected by solar/UV radiation,latitudinal locations,and ozone-depleting reactions were discussed and elaborated.The 2-D ozone Model presented in this paper is a robust,efficient,executable,and validated model for studying the complex ozone phenomena in the stratosphere.

Latitudinal and interannual variations of the spring phytoplankton bloom peak in the East Asian marginal seas

Combined studies of latitudinal and interannual variations of annual phytoplankton bloom peak in East Asian marginal seas(17°–58°N, including the northern South China Sea(SCS), Kuroshio waters, the Sea of Japan and the Okhotsk Sea) are rarely. Based on satellite-retrieved ten-year(2003–2012) median timing of the annual Chlorophyll a concentration(Chl a) climax, here we report that this annual spring bloom peak generally delays from the SCS in January to the Okhotsk Sea in June at a rate of(21.20±2.86) km/d(decadal median±SD). Spring bloom is dominant feature of the phytoplankton annual cycle over these regions, except for the SCS which features winter bloom. The fluctuation of the annual peak timing is mainly within ±48 d departured from the decadal median peak date, therefore this period(the decadal median peak date ±48 d) is defined as annual spring bloom period. As sea surface temperature rises, earlier spring bloom peak timing but decreasing averaged Chl a biomass in the spring bloom period due to insufficient light is evident in the Okhotsk Sea from 2003 to 2012. For the rest of three study domains, there are no significant interannual variance trend of the peak timing and the averaged Chl a biomass. Furthermore this change of spring phytoplankton bloom timing and magnitude in the Okhotsk Sea challenges previous prediction that ocean warming would enhance algal productivity at high latitudes.

Latitudinal distribution of CO_2 and CH_4 on the route of the Chinese Arctic R esearch Expedition 2003

During the 2nd Chinese Arctic Research Expedition, 20 pair of atmospheric samples were collected on the cruising route from Shanghai to Arctic Ocean using NOAA/ESRL flask sampling unit. Mean concentration of CO2 and CH4 were analyzed in different latitude zone from 30°N to 80°N and the distribution characteristics were studied. Mean concentration of CO2 decrease toward high latitude which indicates the uptake effect of CO2 by ocean. Coinciding with the CH4 global distribution character, mean CH4 concentration increase from 45°N to the North Pole region. Regional or local air mass may influence the greenhouse gas concentrations near seashore in the middle latitude （30°N-45°N）.

THE GLOBAL TECTONIC SYSTEMS AND A LATITUDINAL MOUNTAIN-PLATEAU CHAIN ON THE NORTH HEMISPHERE

Three global tectonic systems that formed since the middle Jurassic (160Ma ago)are outlined based on the global map of the Cenozoic and Mesozoic tectonics edited by Ma Zongjin et al.(1996).They are the circum\|Pacific tectonic system,the mid\|ocean ridge tectonic system and the intra\|continental tectonic system of the north hemisphere.The map shows that about 80% of the total length of the continental orogens are concentrate on the north hemisphere of the earth,of which a latitudinal mountain\|plateau chain occur within a zone between north latitude 20°and 50°.Seismic and volcanic activities demonstrate that the intracontinental tectonic system on the north hemisphere is still active.Whilst distribution of the continental deep\|focus earthquakes and almost ultra high\|pressure rock found so far over the World,that are assumed both related to recent or previous deep subduction of continent,along with this zone.The latitudinal mountain\|plateau chain is subdivided into four active tectonic region of Qinghai—Xizang(Tibet),Iranian,eastern mediterranean and North American,both characterized by an individual similar mountain\|plateau\|basin structure with major active boundaries or controlling faults (Fig.1).These active regions are all close to primary dynamic boundaries of continent\|continent collision.Solution of source mechanisms shows that regional tectonic stress field in these regions are dominated by a nearly NS or NNE—SSW direction compression corresponding to a local plate motions and a global compressive zone.Correlation between the formation of the continental latitudinal mountain\|plateau chain on north hemisphere and the oceanic plate tectonics is discussed using the information of the “Map of Magnetic Lineations of the World’s Ocean Basins (Cande et al.,1989)”and the Cenozoic and Mesozoic tectonic evolution in the continents.Total 49 accretion units formed during 6 accretion stages of the ocean spreading in three chief oceans (the Pacific,the India and the Atlantic)si nce 160Ma ago,are subdivided.The distinguished oceanic accretion tectonics in combination with the geometrical and kinematics data of adjust continental f ragments allowed outline of the development of the continental latitudinal tecto nic zone of north hemisphere.Whilst,two global asymmetrical geodynamic systems of north\|south an east\|west direction,that may be composed of meridional conve ction,latitudinal convection and inertial flow resulting from the variation of the Earth’s rotational velocity,are used to discuss on the two global geodynamic systems in which the intracontinental latitudinal tectonic zone developed.

Latitudinal Density Distribution Function of Level Ellipsoid with Isopotential Condition

The implication of density in latitudinal correction to gravity measurement is investigated and the inner Iink of the density or the level ellipsoid with its latitude is also predicted. In this paper the density integral formulae or gravity potential at pole and equator of the revolving ellipsoid are derived. In accordance with the gravity potential condition at pole and on equator of tbe level ellip soid, the Iatitudinal density distribution function of the level ellipsoid is given and further the hypothesis that radial aud longitudinal mean density of the earth normally distribute along latitudinal direction and its latitudinal density on the equator is larger than those at poles is put forward.

PALEOMAGNETIC ESTIMATE OF THE MESOZOIC—CENOZOIC LATITUDINAL DISPLACEMENT OF TERRENES IN THE QINGHAI—TIBET PLATEAU AND ITS SIGNIFICANCE

The Mesozoic—Cenozoic latitudinal displacement amounts of terranes (or blocks) in the Qinghai—Tibet plateau were calculated in paleomagnetism. These terranes (or blocks) include Tarim and Qaidam blocks, East Kunlun, Baryan Har, Qiangtang, Lhasa and Himalaya terranes. The calculated results are listed in table 1. These results show that:(1) There was the latitudinal displacement difference between central area and southwestern area in the Tarim southern margin since the lower Cretaceous. There was a southward latitudinal movement from the beginning of middle Jurassic or upper Jurassic (Zhou Qingjie, 1992). The northward movement amounts of the Tarim northern margin since the Paleocene are greater than that of the Tarim southern margin. Tarim southern margin has moved northward about 1100km since the Paleocene, Tarim northern margin has done about 1700km. Qaidam has moved northward about 3100km since lower\|middle Jurassic. The northward displacement amount of Qaidam since Paleocene is about 810km, near to that of the central area, Tarim southern margin.

Latitudinal patterns of climatic variables and influence of local topography on climatic variables in the dry valleys of southwestern China

Climate is a key factor to determine the pattern of ecosystems;however,the latitudinal patterns of climatic variables in the arid and semiarid areas remain largely unclear when compared to humid areas.The topography of the dry valleys of southwestern China plays an important role in the formation of climate.However,its impact on the climate remains qualitative.In this study,eight climatic variables from 12 meteorological stations were analyzed to explore their latitudinal patterns in the wet and dry seasons from 1961 to 2019.We also quantified the effects of local topography(RH10)on the climatic variables.The results were as follows:sunshine duration,total solar radiation,average temperature,and evaporation decreased significantly,and wind speed increased significantly with increasing latitude in the annual,wet,and dry seasons(P<0.001).Relative humidity and precipitation decreased significantly with increasing latitude in the wet season(P<0.001),and no obvious change pattern was observed in the dry season.Aridity index significantly decreased(toward dryness)with increasing latitude in the wet season and increased in the dry season(P<0.001).Wind speed had a significantly positive relationship with topography(RH10)(P<0.01),whereas precipitation and aridity index were negatively associated with topography in the wet season and positively associated with topography in the dry season.Dryness was positively associated with RH10 in the wet season,and negatively in the dry season.The results of our research could provide new perspectives for understanding the relationship between topography and drought in the dry valleys of southwestern China.

Effect of Chorus Latitudinal Distribution on Evolution of Outer Radiation Belt Electrons

Primary result on the impact of the latitudinal distribution of whistler-mode chorus upon temporal evolution of the phase space density （PSD） of outer radiation belt energetic electrons was presented. We evaluate diffusion rates in pitch angle and momentum due to a band of chorus frequency distributed at a standard Gaussian spectrum, and solve a 2-D bounce-averaged momentum-pitch-angle Fokker-Planck equation at L = 4.5. It is shown that chorus is effective in accelerating electrons and can increase PSD for energy of ～1 MeV by a factor of 10 or more in about one day, which is consistent with observation. Moreover, the latitudinal distribution of chorus has a great impact on the acceleration of electrons. As the latitudinal distribution increases, the efficient acceleration region extends from higher pitch angles to lower pitch angles, and even covers the entire pitch angle region when chorus power reaches the maximum latitude λm = 45°.

Preyminary Investigations on the Global Summer Monsoonal Drought Mechanics and the Latitudinal Teleconnections

The question of possible teleconnections between the middle latitude general circulation and the Indian south-west monsoon was investigated in this paper. Within the framework of a simple model it was shown that there can exist such an interaction via the ultra-long Rossby waves.

Discussing the Oil-Control Effects of the North Latitudinal 38° Belt in Central Part of the Ordos Basin

The Ordos Basin in the western part of the North China Craton is commonly believed to be a multi-controlled oil- bearing basin. It is bounded by the Xing＇an--Mongolian Orogen to the north, the Qingling Orogen to the south, the Lüliang mountain to the east and the Helanshan--Liupanshan mountain belt to the west. The interpretation of geophysical data reveals a latitudinal （38°） fault belt in the centre of the Ordos Basin, which controls the hydrocarbon generation, migration and accumulation in the basin. This study attempts to investigate this belt from outcrops and indicates a structurally controlled system of migration fairway within the fault belt.

Latitudinal differentiation and patterns of temperate and subtropical plants in the Qinling-Daba Mountains

Geographically,the Qinling-Daba Mountains serve as the main body of the north-south transitional zone of China.However,the transitional patterns of their plant species still need to be clarified.This study analyzed latitudinal variations of plant species richness,relative importance values(RIV),and plant species abundance based on plant community field survey data for 163 sample sites along three north-south transect lines in the eastern,middle,and western parts of the study areas.The difference in RIV between subtropical and temperate species(SND-RIV)was selected to reveal the latitudinal interlacing pattern of northern and southern plant species.Along the eastern(Sanmenxia-Yichang),middle(Xi’an-Dazhou),and western(Tianshui-Guangyuan)transects,the richness and RIV of subtropical plant species increased while those of temperate plant species decreased from north to south.In the eastern transect,temperate plant species richness and RIV were the highest at Shennongjia and Funiu Mountain,respectively,because of their high elevations.In the middle transect,subtropical plant species richness and RIV were the highest in the Daba Mountains.In the western transect,richness and RIV were higher for subtropical than temperate plant species from the south of Longnan.The crisscrossing areas of northern and southern plant species were∼180 km,∼100 km,and∼60 km wide for the eastern,middle,and western transects,respectively,showing a narrowing trend from east to west.For the eastern and western transects,decreases in subtropical plant species distribution from south to north could be attributed to a decrease in mean annual precipitation in the same direction.However,for the middle transect,mean annual temperature had a slightly greater influence on plant species’latitudinal distribution than the moisture index.This study provides a more solid scientific basis for future investigations of this key geographical boundary in China.

Physiological but not morphological adjustments along latitudinal gradients in a human commensal species,the Eurasian tree sparrow

Human commensal species take advantage of anthropogenic conditions that are less likely to be challenged by the selective pressures of natural environments.Their morphological and physiological phenotypes can therefore dissociate from habitat characteristics.Understanding how these species adjust their morphological and physiological traits across latitudinal gradients is fundamental to uncovering the eco-physiological strategies underlying coping mechanisms.Here,we studied morphological traits in breeding Eurasian tree sparrows(ETSs;Passer montanus)among low-latitude(Yunnan and Hunan)and middle-latitude(Hebei)localities in China.We then compared body mass;lengths of bill,tarsometatarsus,wing,total body,and tail feather;and baseline and capture stress-induced levels of plasma corticosterone(CORT)and the metabolites including glucose(Glu),total triglyceride(TG),free fatty acid(FFA),total protein,and uric acid(UA).None of the measured morphological parameters varied with latitude except in the Hunan population,which demonstrated longer bills than those in other populations.Stress-induced CORT levels significantly exceeded baseline levels and decreased with increasing latitude,but total integrated CORT levels did not vary with latitude.Capture stress-induced significantly increased Glu levels and decreased TG levels,independent of site.However,the Hunan population had significantly higher baseline CORT,baseline and stress-induced FFA levels,but lower UA levels,which differed from other populations.Our results suggest that rather than morphological adjustments,physiological adjustments are mainly involved in coping mechanisms for middle-latitude adaptation in ETSs.It is worth investigating whether other avian species also exhibit such dissociation from external morphological designs while depending on physiological adjustments.

Latitudinal and Seasonal Variations in Tropical Cyclone-Induced Ocean Surface Cooling in the Tropical Western North Pacific

The passage of tropical cyclones induces ocean surface cooling through vertical mixing,upwelling,and surface heat loss.The dependence of tropical cyclone-induced ocean surface cooling on the intensity and translation speed of tropical cyclones has been documented in previous studies.The present study investigates the latitudinal and seasonal variations in tropical cyclone-induced ocean surface cooling in the tropical western North Pacific based on data for the 2001–2020 period.Our analysis focuses on the open ocean(0°–25°N,130°E–180°)to reduce the interference of coastal topography so that the obtained results better represent the influences of the intensity and translation speed of tropical cyclones.Our analysis confirms the dependence on the intensity and translation speed of tropical cyclone-induced cooling.The new findings are as follows.First,the time to reach the maximum cooling increases with the magnitude of the maximum cooling.Second,the magnitude of ocean surface cooling increases with latitude in the tropical region for tropical cyclones with different intensities and translation speeds.Third,the ocean surface cooling is larger in summer and autumn than in spring for tropical cyclones with different intensities and translation speeds.Fourth,the dependence of ocean surface cooling on the translation speed is more obvious at higher latitudes in the tropics and less apparent in spring.These new findings add to the existing knowledge of the impacts of tropical cyclone intensity and translation speed on ocean surface cooling.

The mid-domain effect in flowering phenology

The timing of flowering is an important driver of species distribution and community assembly patterns.However,we still have much to learn about the factors that shape flowering diversity(i.e.,number of species flowering per period) in plant communities.One potential explanation of flowering diversity is the mid-domain effect,which states that geometric constraints on species ranges within a bounded domain(space or time) will yield a mid-domain peak in diversity regardless of ecological factors.Here,we determine whether the mid-domain effect explains peak flowering time(i.e.,when most species of communities are flowering) across China.We used phenological data of 16,267 herbaceous and woody species from the provincial Flora in China and species distribution data from the Chinese Vascular Plant Distribution Database to determine relationships between the observed number of species flowering and the number of species flowering as predicted by the mid-domain effect model,as well as between three climatic variables(mean minimum monthly temperature,mean monthly precipitation,and mean monthly sunshine duration).We found that the mid-domain effect explained a significant proportion of the temporal variation in flowering diversity across all species in China.Further,the mid-domain effect explained a greater proportion of variance in flowering diversity at higher latitudes than at lower latitudes.The patterns of flowering diversity for both herbaceous and woody species were related to both the mid-domain effect and environmental variables.Our findings indicate that including geometric constraints in conjunction with abiotic and biotic predictors will improve predictions of flowering diversity patterns.

Assessment of the Intertropical Convergence Zone over the Atlantic Ocean through an Algorithm Based on Precipitation

The Intertropical Convergence Zone(ITCZ)is a key atmospheric system on a global scale,primarily driven by trade wind convergence near the equator.The ITCZ plays a crucial role in modulating the climate of the borders of tropical continental areas.For instance,Northeastern Brazil experiences a climate influenced by the ITCZ over the Atlantic Ocean.In some periods,the ITCZ exhibits double bands,known as the double ITCZ.While the features of the ITCZ have been described using various approaches and atmospheric variables,there is still a lack of regional studies focusing on the ITCZ and double ITCZ in the Atlantic Ocean.In this context,the main goals of this study are(1)to describe a simple algorithm based on precipitation to identify the ITCZ and double ITCZ,(2)to present a climatology(1997-2022)of the position,width,and intensity of these two convective bands,and(3)to investigate variabilities in the ITCZ characteristics associated with anomalies of sea surface temperature(SST)in the tropical Pacific and Atlantic oceans.The double ITCZ typically occurs southward of the main cloud band,and between February and April,both bands are more distant(~4.5°).In the western sector of the Atlantic Ocean,the ITCZ and its double band extend to more southerly latitudes in austral autumn.Considering the entire Atlantic basin,the annual mean of the latitudinal position,width,and intensity of the ITCZ is 4.9°N,4.2°,and 11 mm/day,respectively,while for the double ITCZ,it is 0.4°N,2.6°,10.3 mm/day,respectively.While the SST anomalies in the Pacific Ocean(El Niño and La Niña episodes)affect more the ITCZ width,the SST anomalies in the Tropical South Atlantic affect both its position and width.

Earth's density flattening and hypothesis of latitudinal normal density

In this paper, the definition of latitudinal density and density flattening of the level ellipsoid is given, and integral formulas of latitudinal density for pole gravity and equator gravity are derived. According to the pole gravity condition and equator gravity condition for the level ellipsoid, latitudinal density distribution function of the level ellipsoid is obtained. It is proved mathematically that latitudinal density of the earth's equator is larger than that of the pole, the earth's density flat-tening calculated preliminarily is 1/322, and hypothesis of the earth's latitudinal normal density is further proposed, so that theoretical preparation for studying the forming cause of the earth gravity in problems such as continent drift, mantle convection, and submarine extension is made well.

Invasion by alligator weed,Alternanthera philoxeroides,is associated with decreased species diversity across the latitudinal gradient in China

Aims Invasive species occurrence and their effects on biodiversity may vary along latitudes.We examined the occurrence(species cover)and relative dominance(importance value)of invasive alligator weed,Alternanthera philoxeroides,in its terrestrial habitat in China through a large-scale latitudinal field investigation.Methods We established 59 plots along the latitudinal transect from 21°N to 37°N.We recorded species name,abundance,height and individual species coverage of plants in every quadrat.We then measuredα-species diversity variations associated with the A.philoxeroides community across the latitudinal range.We also analyzed the effect of latitude on plant species’distributions in this community by using canonical correspondence analysis(CCA).Important Findings We found that species cover and importance value of A.philoxe-roides increased in areas<35°N,but decreased at higher latitudes.Lower latitudes supported greater species diversity than higher latitudes.Small-scale invasion of A.philoxeroides was associated with higher species diversity,but community diversity was lower when A.philoxeroides species cover exceeded 36%.Community plant species changed from mesophyte to hygrophyte gradually from low to high latitude.Our research suggests that latitude had significant influences on community diversity which interacted with the biotic resistance of a community and impact of invasion.Consequently,A.philoxeroides may become more invasive and have greater negative impacts on community species diversity in higher latitudes as global climate changes.

Latitudinal distribution of iodine in sediments in the Chukchi Sea and the Bering Sea

Iodine is an important trace element associated closely with human being, and it will influence humans normal growth if lacking it. Meanwhile, iodine is an important catalyzer, and is important in atmospheric chemistry study. In nature, iodine is rich mainly in marine organism and sediment, and marine sediment has the largest storage of iodine. The analysis results of sediment samples obtained by the First Chinese National Arctic Research Expedition indicate that iodine contents in sediments in the Chukchi Sea and the Bering Sea are 98.110-6 and 73.810-6, respec-tively, which are higher than those in sediments of Chinese marginal seas and the southern Pacific Ocean, and show the trend of increase from low latitude to high latitude. This paper proposes a pattern of iodine latitudinal distribution on the basis of the distribution characteristic of iodine and its enrichment mechanism in sediments of the Chukchi Sea and the Bering Sea.