Understanding the spatial heterogeneity of debris-flow-prone areas holds significant implications for regional risk management, particularly in seismically active regions with geological faults. Despite the significan...Understanding the spatial heterogeneity of debris-flow-prone areas holds significant implications for regional risk management, particularly in seismically active regions with geological faults. Despite the significance of this knowledge, a comprehensive quantification of the influence of regional topographical and geological factors on the spatial heterogeneity of debris-flow-prone areas has been lacking. This study selected the Hengduan Mountains, an earthquake-prone region characterized by diverse surface conditions and complex landforms, as a representative study area. An improved units zoning and objective factors identification methodology was employed in earthquake and fault analysis to assess the impact of seismic activity and geological factors on spatial heterogeneity of debrisflow prone areas. Results showed that the application of GIS technology with hydrodynamic intensity and geographical units analysis can effectively analyze debris-flow prone areas. Meanwhile, earthquake and fault zones obviously increase the density of debrisflow prone catchments and make them unevenly distributed. The number of debris-flow prone areas shows a nonlinear variation with the gradual increase of geomorphic factor value. Specifically, the area with 1000 m-2500 m elevation difference, 25°-30° average slope, and 0.13-0.15 land use index is the most favorable conditions for debris-flow occurrence;The average annual rainfall from 600 to 1150 mm and landslides gradient from 16° to 35° are the main causal factors to trigger debris flow. Our study sheds light on the quantification of spatial heterogeneity in debris flow-prone areas in earthquake-prone regions, which can offer crucial support for post-debris flow risk management strategies.展开更多
Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in ...Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.展开更多
An integrative study based on morphological data and mitochondrial molecular data of all known Nanorana(sensu stricto)species have revealed a new species from the Hengduan Mountains,N.huangi sp.nov.The new species can...An integrative study based on morphological data and mitochondrial molecular data of all known Nanorana(sensu stricto)species have revealed a new species from the Hengduan Mountains,N.huangi sp.nov.The new species can be distinguished from its congers by its:(1)medium body size,SVL 31.3–40.6 mm in adult males(n=12),39.2–48.1 mm in adult females(n=8);(2)absence of subarticular tubercles on fingers,with supernumerary tubercles below the base of the fingers small but distinct;(3)presence of dark dorsal patches without pale margins,generally creamy yellow ventral body basically,bright yellow ventral limbs;(4)small but prominent tympanum;(5)tibio-tarsal joint that reaches to the tympanum or the shoulder when hindlimbs adpressed forward towards body;(6)head length more than 30%of SVL.In addition,the new species can be separated from all other congeners by uncorrected genetic distances:ranging from 2.8%–7.5%of the mitochondrial 12S rRNA,1.1%–2.1%of the 16S rRNA,and 7.5%–11.5%of the COI.展开更多
Eothenomys miletus(E.miletus)is one of the rodent species found in Yunnan,and it has caused significant harm to local agricultural production.In this study,we aimed to investigate the differences in feeding habits and...Eothenomys miletus(E.miletus)is one of the rodent species found in Yunnan,and it has caused significant harm to local agricultural production.In this study,we aimed to investigate the differences in feeding habits and stomach fungi of E.miletus across different areas in the Hengduan mountain regions.By exploring the main factors affecting the feeding habits and fungi of E.miletus,this study provides a theoretical basis for the prevention and control of this species.We collected E.miletus specimens from five regions,namely Deqin,Xianggelila,Lijiang,Jianchuan,and Ailaoshan.We measured their feeding habits and the types of fungi in their stomachs using high-throughput sequencing technology.The results showed that E.miletus primarily fed on Poaceae,Oxalidaceae,Asteraceae,and Fabaceae.Food diversity of E.miletus in Ailaoshan and Jianchuan was significantly lower than in the other three regions.As for stomach fungi,Ascomycota and Basidiomycota were the absolute dominant sectors.Changes in the diversity of fungi in different regions were consistent with changes in food diversity.The diversity of fungi in Ailaoshan and Jianchuan regions was lower than in the other three regions.These findings suggest that the feeding habits of E.miletus in different regions were affected by plant species,which,in turn,affects the diversity of fungi in their stomachs.展开更多
Until recently, the agamid species, Japalura flaviceps was recognized to have the widest geographic dis- tribution among members of the genus occurring in China, from eastern Tibet to Shaanxi Province. However, recent...Until recently, the agamid species, Japalura flaviceps was recognized to have the widest geographic dis- tribution among members of the genus occurring in China, from eastern Tibet to Shaanxi Province. However, recent studies restricted the distribution of J. flaviceps to the Dadu River valley only in north- western Sichuan Province, suggesting that records of J. flaviceps outside the Dadu River valley likely represent undescribed diversity. During two herpeto- faunal surveys in 2013 and 2015, eight and 12 specimens of lizards of the genus Japalura were collected from the upper Nujiang (=Salween) Valley in eastern Tibet, China, and upper Lancang (=Mekong) Valley in northwestern Yunnan, China, respectively. These specimens display a unique suite of diagnostic morphological characters. Our robust comparisons of phenotype reveal that these populations can be distinguished readily from J. flaviceps and all other recognized congeners. Herein, we describe the two Japalura lineages as new spe- cies, Japalura laeviventris sp. nov. and Japalura iadina sp. nov.. In addition, we provide updated con- servation assessments for the new species as well as imperiled congeners according to the IUCN crite- ria for classification, discuss the importance of color patterns in the diagnosis and description of species in the genus Japalura, and discuss directions for future taxonomic studies of the group.展开更多
1.Introduction The Hengduan Mountains region(HDM)in southwest China,one of the earth's 34 biodiversity hotspots,is characterized by its unique geology,dramatic topography,a climate where snow and below freezing te...1.Introduction The Hengduan Mountains region(HDM)in southwest China,one of the earth's 34 biodiversity hotspots,is characterized by its unique geology,dramatic topography,a climate where snow and below freezing temperatures can occur on any day of the year,by its location at elevations averaging between(1400e)2000 and4500(e5300)meters above sea level(m a.s.l.),and by one of展开更多
To detect the horizontal pattern of phylogenetic structure shown by alpine plants, we measured phylogenetic structure using net related index(NRI) and net nearest taxon index(NTI), and analyzed the phylogenetic struct...To detect the horizontal pattern of phylogenetic structure shown by alpine plants, we measured phylogenetic structure using net related index(NRI) and net nearest taxon index(NTI), and analyzed the phylogenetic structure patterns of alpine plants along longitude, latitude and environmental gradients in the Hengduan Mountains Region(HDMR). Our results show that: 1) the phylogenetic structure tended to cluster with increasing latitude and longitude; 2) for NRI, latitude was closer related than longitude,while for NTI, longitude was closer related than latitude, though they both not significantly relate to NTI.The phylogenetic structure tended towards overdispersion in the southern HDMR, with good climate conditions of higher mean annual temperature and more mean annual precipitation. In contrast, with harsh climate conditions of lower mean annual temperature and less mean annual precipitation, the increasing environmental stress led to phylogenetic clustering in the northern HDMR. The results highlighted that in the alpine region of HDMR, environmental filters and geographical isolation had a great effect on the latitudinal and longitudinal alpine species distribution, respectively.展开更多
Zokors in the genus Eospalax,which are endemic to northern and western China,are subterranean rodents that inhabit various niches,including grasslands,high-altitude meadows,forests,and farmlands.Six species in Eospala...Zokors in the genus Eospalax,which are endemic to northern and western China,are subterranean rodents that inhabit various niches,including grasslands,high-altitude meadows,forests,and farmlands.Six species in Eospalax were described a century ago but their taxonomy and phylogeny remain controversial.In this study,we performed high-depth whole-genome sequencing of 47 zokor samples,comprising all six previously described species.Genomic analyses revealed a reliable and robust phylogeny of Eospalax and supported the validity of the six named species.According to the inferred phylogenetic relationships,Eospalax first divergent into two clades in the early Pliocene(ca.4.68 million years ago(Ma)),one inhabiting the highaltitude Qinghai-Xizang(Tibet)Plateau(QTP)and adjacent regions,and the another inhabiting the lowaltitude Loess Plateau and Qinling-Daba Mountains.The most recent divergences occurred between E.baileyi and E.smithii and between E.rufescens and E.rothschildi in the late Pliocene(ca.2.09 and 2.19 Ma,respectively).We also collected specimens of zokors in the southern Hengduan Mountains(Muli County,Sichuan Province),far from the known distributions of all other zokors.Morphological and molecular analyses strongly suggested that the specimens represent a new species,formally described here as Eospalax muliensis sp.nov.The new species belongs to the high-altitude clade and diverged from closely related species(ca.4.22 Ma)shortly after the first divergence in Eospalax.Interestingly,Eospalax muliensis sp.nov.possesses more supposedly plesiomorphic characters,suggesting a possible origin of the genus in the Hengduan Mountains.展开更多
Background:Natural forests in the Hengduan Mountains Region(HDMR)have pivotal ecological functions and provide diverse ecosystem services.Capturing long-term forest disturbance and drivers at a regional scale is cruci...Background:Natural forests in the Hengduan Mountains Region(HDMR)have pivotal ecological functions and provide diverse ecosystem services.Capturing long-term forest disturbance and drivers at a regional scale is crucial for sustainable forest management and biodiversity conservation.Methods:We used 30-m resolution Landsat time series images and the LandTrendr algorithm on the Google Earth Engine cloud platform to map forest disturbances at an annual time scale between 1990 and 2020 and attributed causal agents of forest disturbance,including fire,logging,road construction and insects,using disturbance properties and spectral and topographic variables in the random forest model.Results:The conventional and area-adjusted overall accuracies(OAs)of the forest disturbance map were 92.3% and 97.70%±0.06%,respectively,and the OA of mapping disturbance agents was 85.80%.The estimated disturbed forest area totalled 3313.13 km^(2)(approximately 2.31% of the total forest area in 1990)from 1990 to 2020,with considerable interannual fluctuations and significant regional differences.The predominant disturbance agent was fire,which comprised approximately 83.33% of the forest area disturbance,followed by logging(12.2%),insects(2.4%)and road construction(2.0%).Massive forest disturbances occurred mainly before 2000,and the post-2000 annual disturbance area significantly dropped by 55% compared with the pre-2000 value.Conclusions:This study provided spatially explicit and retrospective information on annual forest disturbance and associated agents in the HDMR.The findings suggest that China’s logging bans in natural forests combined with other forest sustainability programmes have effectively curbed forest disturbances in the HDMR,which has implications for enhancing future forest management and biodiversity conservation.展开更多
Elevational patterns of trait occurrence and functional diversity provide an important perspective for understanding biodiversity.However,previous studies have mostly examined functional diversity at the community sca...Elevational patterns of trait occurrence and functional diversity provide an important perspective for understanding biodiversity.However,previous studies have mostly examined functional diversity at the community scale.Here,we examined large-scale patterns of trait occurrence and functional diversity in Delphinium along an elevational gradient from 1000 to 5700 m in the Hengduan Mountains,SW China.Elevational distribution and trait data of 102 Delphinium species were compiled to evaluate the patterns of interspecific traits,species richness,and functional diversity.We found that the distribution of species richness showed a unimodal curve that peaked between 3500 and 4000 m;functional diversity and traits showed different patterns along an elevational gradient The functional diversity increased at a lower rate along an elevation gradient,whereas species richness continued to increase.Species with large ranges and non-endemic species were most affected by geometric constraints.Richness of species endemic to the Hengduan Mountains peaked at higher elevations,likely due to increased speciation and restricted dispersion under alpine conditions.We conclude that the middle elevation region is not only the functionally richest but also the most functionally stable region for Delphinium,which could be insurance against environmental change.Extreme conditions and strong environmental filters in an alpine environment may cause the convergence of species traits,which could relate to reducing nutrient trait investment and increasing reproductive trait investment.We conclude that large-scale studies are consistent with previous studies at the community scale.This may indicate that the relationship between functional diversity and species richness across different scales is the same.展开更多
Clonal reproduction(i.e.,production of potentially independent offspring by vegetative growth)is thought to provide plants with reproductive assurance.Thus,studying the evolution of clonal reproduction in local floras...Clonal reproduction(i.e.,production of potentially independent offspring by vegetative growth)is thought to provide plants with reproductive assurance.Thus,studying the evolution of clonal reproduction in local floras is crucial for our understanding of the adaptive mechanisms plants deploy in stressful environments such as alpine regions.In this study,we characterized clonal plant species in the subnival belt of the Hengduan Mountains(a global biodiversity hotspot with extreme environmental conditions in southwest China),in order to determine the effects of sex system,growth form,and elevational distribution on clonality.We compiled clonality data of angiosperm species belonging to 41 families in the subnival belt of the Hengduan Mountains using published information.Of the 793 species recorded in the region,47.92%(380 species)are clonal species.Both sex system and growth form had significant effects on the occurrence of clonal reproduction:unisexual species(79.79%)were more likely to be clonal than bisexual species(43.63%),and herbaceous species(51.04%)were more likely to be clonal than woody species(16.67%).Compared with non-alpine-endemic species(44.60%),alpine-endemic species(58.33%)showed a significantly higher proportion of clonal reproduction.Further logistic regression analysis showed a positive association between incidence of clonality and elevational range,indicating that species distributed at high elevations are more likely to be clonal.Furthermore,the elevational gradients in clonality were contingent on sex system or growth form.This study reveals that plants in the subnival belt of the Hengduan Mountains might optimize their probability of reproduction through clonal reproduction,a finding that adds to our growing understanding of plant's adaptations to harsh alpine environments.展开更多
[Objective] The aim was to study the spatial information of temperature and precipitation data in Hengduan mountains. [Method] Considering GIS spatial interpolation and numerical statistics theory, spatial prediction ...[Objective] The aim was to study the spatial information of temperature and precipitation data in Hengduan mountains. [Method] Considering GIS spatial interpolation and numerical statistics theory, spatial prediction were carried out to the ten years average temperature and precipitation flux observation data in 109 sparse meteorological stations in Hengduan Mountains. Based on the spatial range of geographic position of Hengduan Mountains, and 1∶1 000 000 scale DEM as data sources, and using trend surface simulation and residual ordinary Kriging interpolation correction method, the spatial continuous surface for annual average temperature and precipitation were studied. [Result] It was scientific and reasonable to use certain unevenly distributed sparse climate observation station value, and by dint of trend simulation and residue interpolation method to get climate consecutive spatial result. This method can not only accurate the temperature and precipitation spatial distributions to grid point, but also can reflect macro and micro geography factors and topographic influence factor of variation. Furthermore, it can be predicted error term trend surface reasonable spatial distribution. Simulation results were basically in accordance with the objective law, and can be used for the region climate data spatial informatization simulation. [Conclusion] The study provided scientific spatial basic data for the further study of ecological and vegetation in Hengduan Mountains.展开更多
Polyploids contribute substantially to plant evolution and biodiversity;however,the mechanisms by which they succeed are still unclear.According to the polyploid adaptation hypothesis,successful polyploids spread by r...Polyploids contribute substantially to plant evolution and biodiversity;however,the mechanisms by which they succeed are still unclear.According to the polyploid adaptation hypothesis,successful polyploids spread by repeated adaptive responses to new environments.Here,we tested this hypothesis using two tetraploid yellowcresses(Rorippa),the endemic Rorippa elata and the widespread Rorippa palustris,in the temperate biodiversity hotspot of the Hengduan Mountains.Speciation modes were resolved by phylogenetic modeling using 12 low-copy nuclear loci.Phylogeographical patterns were then examined using haplotypes phased from four plastid and ITS markers,coupled with historical niche reconstruction by ecological niche modeling.We inferred the time of hybrid origins for both species as the mid-Pleistocene,with shared glacial refugia within the southern Hengduan Mountains.Phylogeographic and ecological niche reconstruction indicated recurrent northward colonization by both species after speciation,possibly tracking denuded habitats created by glacial retreat during interglacial periods.Common garden experiment involving perennial R.elata conducted over two years revealed significant changes in fitness-related traits across source latitudes or altitudes,including latitudinal increases in survival rate and compactness of plant architecture,suggesting gradual adaptation during range expansion.These findings support the polyploid adaptation hypothesis and suggest that the spread of polyploids was aided by adaptive responses to environmental changes during the Pleistocene.Our results thus provide insight into the evolutionary success of polyploids in high-altitude environments.展开更多
A population of Japalura from Yunnan Province, China, previously assigned to Japalura splendida, is described as a new species. The new species has been recorded between 1 138–2 500 m in the Nu River drainage between...A population of Japalura from Yunnan Province, China, previously assigned to Japalura splendida, is described as a new species. The new species has been recorded between 1 138–2 500 m in the Nu River drainage between the towns of Liuku and Binzhongluo, and on the lower western slopes of the Nushan and eastern slopes of the Goaligongshan. The new species can be distinguished from other species of Japalura, except J. dymondi, by the following combination of characters: exposed tympani, prominent dorso-lateral stripes, and small gular scales. It is very similar with but differs from J. dymondi by having smooth or feebly keeled dorsal head scales, three relatively enlarged spines on either side of the post-occiput area, strongly keeled and mucronate scales on occiput area and within the lateral stripes, back of arm and leg green, higher number of dorsal-ridge scales(DS) and fourth toe subdigital scales(T4S). A principal component analysis of body measurements of adult male specimens of the new species and J. dymondi showed principal component 1 loading highest for upper arm length, fourth toe length and snout to eye length and principal component 2 loading highest for head width, head length and fourth toe length.展开更多
The Hengduan Mountains region is a biodiversity hotspot. In this study, we report the karyotypes of 19 species(21 populations) of Asteraceae from this region, 14 of which are reported for the first time. We also exami...The Hengduan Mountains region is a biodiversity hotspot. In this study, we report the karyotypes of 19 species(21 populations) of Asteraceae from this region, 14 of which are reported for the first time. We also examined polyploidy in Asteraceae plants and summarized karyotype data in the literature for 69 congeneric taxa. In these genera, there were five different ploidy levels in the region, though the most dominant was diploid(73.08%). There is no direct evidence that ploidy level and karyotype asymmetry are associated with the distribution of recorded Asteraceae species from the Hengduan Mountains. This suggests that polyploidy(26.92%) may not play an important role in the evolutionary history of these plants, even though, among these genera, the ratio of paleopolyploidy was high(46.15%).展开更多
Perhaps no region on earth presents such a confusing array of place names as does the area made up of the former provinces of Kham and Amdo in historic Tibet (Xizang). Within these areas, cities, towns, villages, moun...Perhaps no region on earth presents such a confusing array of place names as does the area made up of the former provinces of Kham and Amdo in historic Tibet (Xizang). Within these areas, cities, towns, villages, mountains, lakes and other geographic features have at least two names applied to them, one Tibetan, the other Chinese. Overlying this indigenous nomenclature are the names applied by outsiders, mostly Europeans, each of whom used their native language to transliterate the names they heard or read from Tibetan or Chinese script, and names in the languages of other ethnic minorities who live within the area. Adding to the confusion are the conflicting “standards” for transliterating Tibetan and Chinese names. To resolve the inconsistencies and uncertainties of place names in this region, a multilingual gazetteer and thesaurus was prepared. The gazetteer-thesaurus was compiled to be used as a tool for correlating the often radically different names assigned to a single place or feature and to provide the geographic coordinates for each. The impetus for this project was the need to assign geographic coordinates to plant specimens collected in the area since the latter part of the 19th century up until the advent and widespread use of Global Positioning System (GPS) receivers in the 1990s. Georeferencing specimens is necessary for plotting the historical distribution of species and for more completely understanding the information contained on specimen labels. Knowing the distribution of plants is important for answering phylogenetic questions, determining local and widespread biogeographical patterns, identifying areas of unusually high diversity or endemism, and determining areas in need of special protection. The value of such a gazetteer, however, extends well beyond the field of botany. It is intended to be of use to anyone with a desire to know the nomenclatural history of places in the area and for pinpointing with a fair degree of accuracy the location of each of those places.展开更多
The Fraction of Absorbed Photosynthetically Active Radiation(FPAR) is an important indicator of the primary productivity of vegetation. FPAR is often used to estimate the assimilation of carbon dioxide in vegetation. ...The Fraction of Absorbed Photosynthetically Active Radiation(FPAR) is an important indicator of the primary productivity of vegetation. FPAR is often used to estimate the assimilation of carbon dioxide in vegetation. Based on MOD15 A2 H/FPAR data product, the temporal and spatial variation characteristics and variation trend of FPAR in different vegetation types in 2001 to 2018 were analyzed in the Hengduan Mountains. The response of FPAR to climate change was investigated by using Pearson correlation analytical method and partial least squares regression analysis. Results showed that the FPAR in Hengduan Mountains presented an increasing trend with time. Spatially, it was high in the south and low in the north, and it also showed obvious vertical zonality by elevation gradient.The vegetation FPAR was found to be positively correlated with air temperature and sunshine duration but negatively correlated with precipitation. Partial least squares regression analysis showed that the influence of sunshine duration on vegetation FPAR in Hengduan Mountains was stronger than that of air temperature and precipitation.展开更多
Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification andgeologic significance of whole-rock Rb-Sr isochrons as well as the factors influencing homogenization of theisotopic...Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification andgeologic significance of whole-rock Rb-Sr isochrons as well as the factors influencing homogenization of theisotopic systems are discussed. Usually. there is no good linear correlation of isochrons for diorites andalkali-rich intrusive rocks (including alkaline rock and alkalic granite). But by means of the external isochron ofmonominerals from the rocks. isochrons with good linear correlation as well as ages and Sr initial ratios with ahigh confidence can be obtained. In order to obtain a satisfactory isochron, the discriminant parameters shouldbe calculated from the Rb/Sr ratios and estimated ages of samples. Only those that meet the requirements canbe used as the Rb-Sr isochrons. The quality of an isochron should be judged from three factors, i.e. correlationcoefficient. MSWD and homogenization degree.展开更多
Variations and trends in extreme climate events are more sensitive to climate change than the mean values,and so have received much attention.In this study,twelve indices of temperature extremes and 11 indices of prec...Variations and trends in extreme climate events are more sensitive to climate change than the mean values,and so have received much attention.In this study,twelve indices of temperature extremes and 11 indices of precipitation extremes at 32 meteorological stations in Hengduan Mountains were examined for the period 1961-2008.The results reveal statistically significant increases in the temperature of the warmest and coldest nights and in the frequencies of extreme warm days and nights.Decreases of the diurnal temperature range and the numbers of frost days and ice days are statistically significant.Regional averages of growing season length also display the trends consistent and significant with warming.At a large proportion of the stations,patterns of temperature extremes are consistent with warming since 1961:warming trends in minimum temperature indices are greater than those relating to maximum temperature.As the center of the Shaluli Mountain,the warming magnitudes decrease from inner to outer.Changes in precipitation extremes is low:trends are difficult to detect against the larger inter-annual and decadal-scale variability of precipitation,and only the wet day precipitation and the regional trend in consecutive dry days are significant at the 0.05 level.It can be concluded that the variation of extreme precipitation events is not obvious in the Hengduan Mountains,however,the regional trends generally decrease from the south to the north.Overall,the spatial distribution of temporal changes of all extreme climate indices in the Hengduan Mountains illustrated here reflects the climatic complexity in mountainous regions.展开更多
基金supported by the Hubei Provincial Engineering Research Center of Slope Habitat Construction Technique Using Cement-based Materials Open Research Program (Grant No. 2022SNJ112022SNJ12)+4 种基金National Natural Science Foundation of China (Grant No. 42371014)Hubei Key Laboratory of Disaster Prevention and Mitigation (China Three Gorges University) Open Research Program (Grant No. 2022KJZ122023KJZ19)CRSRI Open Research Program (Grant No. CKWV2021888/KY)the Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences (Grant No. KLMHESP20-0)。
文摘Understanding the spatial heterogeneity of debris-flow-prone areas holds significant implications for regional risk management, particularly in seismically active regions with geological faults. Despite the significance of this knowledge, a comprehensive quantification of the influence of regional topographical and geological factors on the spatial heterogeneity of debris-flow-prone areas has been lacking. This study selected the Hengduan Mountains, an earthquake-prone region characterized by diverse surface conditions and complex landforms, as a representative study area. An improved units zoning and objective factors identification methodology was employed in earthquake and fault analysis to assess the impact of seismic activity and geological factors on spatial heterogeneity of debrisflow prone areas. Results showed that the application of GIS technology with hydrodynamic intensity and geographical units analysis can effectively analyze debris-flow prone areas. Meanwhile, earthquake and fault zones obviously increase the density of debrisflow prone catchments and make them unevenly distributed. The number of debris-flow prone areas shows a nonlinear variation with the gradual increase of geomorphic factor value. Specifically, the area with 1000 m-2500 m elevation difference, 25°-30° average slope, and 0.13-0.15 land use index is the most favorable conditions for debris-flow occurrence;The average annual rainfall from 600 to 1150 mm and landslides gradient from 16° to 35° are the main causal factors to trigger debris flow. Our study sheds light on the quantification of spatial heterogeneity in debris flow-prone areas in earthquake-prone regions, which can offer crucial support for post-debris flow risk management strategies.
基金the National Natural Science Foundation of China(Grant Nos.42205059 and 42005075)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA23090303 and XDB40010302)+1 种基金the State Key Laboratory of Cryospheric Science(Grant No.SKLCS-ZZ-2024 and SKLCS-ZZ-2023)the Key Laboratory of Mountain Hazards and Earth Surface Processes.
文摘Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.
基金This work is supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,Grant No.2019QZKK05010503)China Biodiversity Observation Networks(Sino BON-Amphibian and Reptile)+1 种基金Field work was conducted under permission of the Forestry and Grassland Administration of Xizang Autonomous Region(No.2021[71])Forestry and Grassland Administration of Yunnan Province(No.2019[825]).
文摘An integrative study based on morphological data and mitochondrial molecular data of all known Nanorana(sensu stricto)species have revealed a new species from the Hengduan Mountains,N.huangi sp.nov.The new species can be distinguished from its congers by its:(1)medium body size,SVL 31.3–40.6 mm in adult males(n=12),39.2–48.1 mm in adult females(n=8);(2)absence of subarticular tubercles on fingers,with supernumerary tubercles below the base of the fingers small but distinct;(3)presence of dark dorsal patches without pale margins,generally creamy yellow ventral body basically,bright yellow ventral limbs;(4)small but prominent tympanum;(5)tibio-tarsal joint that reaches to the tympanum or the shoulder when hindlimbs adpressed forward towards body;(6)head length more than 30%of SVL.In addition,the new species can be separated from all other congeners by uncorrected genetic distances:ranging from 2.8%–7.5%of the mitochondrial 12S rRNA,1.1%–2.1%of the 16S rRNA,and 7.5%–11.5%of the COI.
基金This work was supported by the National Natural Scientific Foundation of China(No.32160254)Yunnan Ten Thousand Talents Plan Young and Elite Talents Project(YNWR-QNRC-2019-047)Yunnan Provincial Middle-Young Academic and Technical Leader candidate(2019HB013).
文摘Eothenomys miletus(E.miletus)is one of the rodent species found in Yunnan,and it has caused significant harm to local agricultural production.In this study,we aimed to investigate the differences in feeding habits and stomach fungi of E.miletus across different areas in the Hengduan mountain regions.By exploring the main factors affecting the feeding habits and fungi of E.miletus,this study provides a theoretical basis for the prevention and control of this species.We collected E.miletus specimens from five regions,namely Deqin,Xianggelila,Lijiang,Jianchuan,and Ailaoshan.We measured their feeding habits and the types of fungi in their stomachs using high-throughput sequencing technology.The results showed that E.miletus primarily fed on Poaceae,Oxalidaceae,Asteraceae,and Fabaceae.Food diversity of E.miletus in Ailaoshan and Jianchuan was significantly lower than in the other three regions.As for stomach fungi,Ascomycota and Basidiomycota were the absolute dominant sectors.Changes in the diversity of fungi in different regions were consistent with changes in food diversity.The diversity of fungi in Ailaoshan and Jianchuan regions was lower than in the other three regions.These findings suggest that the feeding habits of E.miletus in different regions were affected by plant species,which,in turn,affects the diversity of fungi in their stomachs.
基金supported by the National Natural Science Foundation of China,Grant No.30670146the National Infrastructure of Natural Resources for Science and Technology,Grant No.2005DKA21403.
基金supported by the Ministry of Science and Technology of China(2014FY210200,2011FY120200)the Animal Branch of the Germplasm Bank of Wild Species of Chinese Academy of Sciences(the Large Research Infrastructure Funding)
文摘Until recently, the agamid species, Japalura flaviceps was recognized to have the widest geographic dis- tribution among members of the genus occurring in China, from eastern Tibet to Shaanxi Province. However, recent studies restricted the distribution of J. flaviceps to the Dadu River valley only in north- western Sichuan Province, suggesting that records of J. flaviceps outside the Dadu River valley likely represent undescribed diversity. During two herpeto- faunal surveys in 2013 and 2015, eight and 12 specimens of lizards of the genus Japalura were collected from the upper Nujiang (=Salween) Valley in eastern Tibet, China, and upper Lancang (=Mekong) Valley in northwestern Yunnan, China, respectively. These specimens display a unique suite of diagnostic morphological characters. Our robust comparisons of phenotype reveal that these populations can be distinguished readily from J. flaviceps and all other recognized congeners. Herein, we describe the two Japalura lineages as new spe- cies, Japalura laeviventris sp. nov. and Japalura iadina sp. nov.. In addition, we provide updated con- servation assessments for the new species as well as imperiled congeners according to the IUCN crite- ria for classification, discuss the importance of color patterns in the diagnosis and description of species in the genus Japalura, and discuss directions for future taxonomic studies of the group.
基金funded by the Major Program of the National Natural Science Foundation of China (31590823 to H.S.),the National Natural Science Foundation of China(31370004 and 31570213 to J.W.Z.,31700165 to T.D.)the National Key R&D Program of China (2017YFC0505200 to H.S.)CAS ‘Light of West China’ Program to T.D.
文摘1.Introduction The Hengduan Mountains region(HDM)in southwest China,one of the earth's 34 biodiversity hotspots,is characterized by its unique geology,dramatic topography,a climate where snow and below freezing temperatures can occur on any day of the year,by its location at elevations averaging between(1400e)2000 and4500(e5300)meters above sea level(m a.s.l.),and by one of
基金supported by Major Program of National Natural Science Foundation of China grant no. 31590823 to Hang Sunthe National Natural Science Foundation of China (NSFC) Grant No. 31560063Key Disciplines (Ecology) Project of Yunnan Education Department
文摘To detect the horizontal pattern of phylogenetic structure shown by alpine plants, we measured phylogenetic structure using net related index(NRI) and net nearest taxon index(NTI), and analyzed the phylogenetic structure patterns of alpine plants along longitude, latitude and environmental gradients in the Hengduan Mountains Region(HDMR). Our results show that: 1) the phylogenetic structure tended to cluster with increasing latitude and longitude; 2) for NRI, latitude was closer related than longitude,while for NTI, longitude was closer related than latitude, though they both not significantly relate to NTI.The phylogenetic structure tended towards overdispersion in the southern HDMR, with good climate conditions of higher mean annual temperature and more mean annual precipitation. In contrast, with harsh climate conditions of lower mean annual temperature and less mean annual precipitation, the increasing environmental stress led to phylogenetic clustering in the northern HDMR. The results highlighted that in the alpine region of HDMR, environmental filters and geographical isolation had a great effect on the latitudinal and longitudinal alpine species distribution, respectively.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK05010218,2019QZKK05010110)National Natural Science Foundation of China(32100339,31871277)+2 种基金supported by the Yunling Scholar ProjectTen-Thousand Talents Plan of Yunnan Provincesupported by the Youth Innovation Promotion Association,Chinese Academy of Sciences。
文摘Zokors in the genus Eospalax,which are endemic to northern and western China,are subterranean rodents that inhabit various niches,including grasslands,high-altitude meadows,forests,and farmlands.Six species in Eospalax were described a century ago but their taxonomy and phylogeny remain controversial.In this study,we performed high-depth whole-genome sequencing of 47 zokor samples,comprising all six previously described species.Genomic analyses revealed a reliable and robust phylogeny of Eospalax and supported the validity of the six named species.According to the inferred phylogenetic relationships,Eospalax first divergent into two clades in the early Pliocene(ca.4.68 million years ago(Ma)),one inhabiting the highaltitude Qinghai-Xizang(Tibet)Plateau(QTP)and adjacent regions,and the another inhabiting the lowaltitude Loess Plateau and Qinling-Daba Mountains.The most recent divergences occurred between E.baileyi and E.smithii and between E.rufescens and E.rothschildi in the late Pliocene(ca.2.09 and 2.19 Ma,respectively).We also collected specimens of zokors in the southern Hengduan Mountains(Muli County,Sichuan Province),far from the known distributions of all other zokors.Morphological and molecular analyses strongly suggested that the specimens represent a new species,formally described here as Eospalax muliensis sp.nov.The new species belongs to the high-altitude clade and diverged from closely related species(ca.4.22 Ma)shortly after the first divergence in Eospalax.Interestingly,Eospalax muliensis sp.nov.possesses more supposedly plesiomorphic characters,suggesting a possible origin of the genus in the Hengduan Mountains.
基金jointly funded by the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK04020103)National Natural Science Foundation of China(41971239)programme for provincial innovative team of the climate change study of the Greater Mekong Subregion(2019HC027).
文摘Background:Natural forests in the Hengduan Mountains Region(HDMR)have pivotal ecological functions and provide diverse ecosystem services.Capturing long-term forest disturbance and drivers at a regional scale is crucial for sustainable forest management and biodiversity conservation.Methods:We used 30-m resolution Landsat time series images and the LandTrendr algorithm on the Google Earth Engine cloud platform to map forest disturbances at an annual time scale between 1990 and 2020 and attributed causal agents of forest disturbance,including fire,logging,road construction and insects,using disturbance properties and spectral and topographic variables in the random forest model.Results:The conventional and area-adjusted overall accuracies(OAs)of the forest disturbance map were 92.3% and 97.70%±0.06%,respectively,and the OA of mapping disturbance agents was 85.80%.The estimated disturbed forest area totalled 3313.13 km^(2)(approximately 2.31% of the total forest area in 1990)from 1990 to 2020,with considerable interannual fluctuations and significant regional differences.The predominant disturbance agent was fire,which comprised approximately 83.33% of the forest area disturbance,followed by logging(12.2%),insects(2.4%)and road construction(2.0%).Massive forest disturbances occurred mainly before 2000,and the post-2000 annual disturbance area significantly dropped by 55% compared with the pre-2000 value.Conclusions:This study provided spatially explicit and retrospective information on annual forest disturbance and associated agents in the HDMR.The findings suggest that China’s logging bans in natural forests combined with other forest sustainability programmes have effectively curbed forest disturbances in the HDMR,which has implications for enhancing future forest management and biodiversity conservation.
基金We thank Jiahui Chen for his kind help to provide the data source of functional traits.We thank Lu Sun for his kind help with R.This study was supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0502)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20050203)and the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U1802232).
文摘Elevational patterns of trait occurrence and functional diversity provide an important perspective for understanding biodiversity.However,previous studies have mostly examined functional diversity at the community scale.Here,we examined large-scale patterns of trait occurrence and functional diversity in Delphinium along an elevational gradient from 1000 to 5700 m in the Hengduan Mountains,SW China.Elevational distribution and trait data of 102 Delphinium species were compiled to evaluate the patterns of interspecific traits,species richness,and functional diversity.We found that the distribution of species richness showed a unimodal curve that peaked between 3500 and 4000 m;functional diversity and traits showed different patterns along an elevational gradient The functional diversity increased at a lower rate along an elevation gradient,whereas species richness continued to increase.Species with large ranges and non-endemic species were most affected by geometric constraints.Richness of species endemic to the Hengduan Mountains peaked at higher elevations,likely due to increased speciation and restricted dispersion under alpine conditions.We conclude that the middle elevation region is not only the functionally richest but also the most functionally stable region for Delphinium,which could be insurance against environmental change.Extreme conditions and strong environmental filters in an alpine environment may cause the convergence of species traits,which could relate to reducing nutrient trait investment and increasing reproductive trait investment.We conclude that large-scale studies are consistent with previous studies at the community scale.This may indicate that the relationship between functional diversity and species richness across different scales is the same.
基金This work was supported by the Science Research Foundation of Yunnan Provincial Department of Education(2019J0551 to Y.Q.Gao).
文摘Clonal reproduction(i.e.,production of potentially independent offspring by vegetative growth)is thought to provide plants with reproductive assurance.Thus,studying the evolution of clonal reproduction in local floras is crucial for our understanding of the adaptive mechanisms plants deploy in stressful environments such as alpine regions.In this study,we characterized clonal plant species in the subnival belt of the Hengduan Mountains(a global biodiversity hotspot with extreme environmental conditions in southwest China),in order to determine the effects of sex system,growth form,and elevational distribution on clonality.We compiled clonality data of angiosperm species belonging to 41 families in the subnival belt of the Hengduan Mountains using published information.Of the 793 species recorded in the region,47.92%(380 species)are clonal species.Both sex system and growth form had significant effects on the occurrence of clonal reproduction:unisexual species(79.79%)were more likely to be clonal than bisexual species(43.63%),and herbaceous species(51.04%)were more likely to be clonal than woody species(16.67%).Compared with non-alpine-endemic species(44.60%),alpine-endemic species(58.33%)showed a significantly higher proportion of clonal reproduction.Further logistic regression analysis showed a positive association between incidence of clonality and elevational range,indicating that species distributed at high elevations are more likely to be clonal.Furthermore,the elevational gradients in clonality were contingent on sex system or growth form.This study reveals that plants in the subnival belt of the Hengduan Mountains might optimize their probability of reproduction through clonal reproduction,a finding that adds to our growing understanding of plant's adaptations to harsh alpine environments.
基金Supported by Forest Management Key Subject Construction Project of Southwest Forestry University(XKZ200901)
文摘[Objective] The aim was to study the spatial information of temperature and precipitation data in Hengduan mountains. [Method] Considering GIS spatial interpolation and numerical statistics theory, spatial prediction were carried out to the ten years average temperature and precipitation flux observation data in 109 sparse meteorological stations in Hengduan Mountains. Based on the spatial range of geographic position of Hengduan Mountains, and 1∶1 000 000 scale DEM as data sources, and using trend surface simulation and residual ordinary Kriging interpolation correction method, the spatial continuous surface for annual average temperature and precipitation were studied. [Result] It was scientific and reasonable to use certain unevenly distributed sparse climate observation station value, and by dint of trend simulation and residue interpolation method to get climate consecutive spatial result. This method can not only accurate the temperature and precipitation spatial distributions to grid point, but also can reflect macro and micro geography factors and topographic influence factor of variation. Furthermore, it can be predicted error term trend surface reasonable spatial distribution. Simulation results were basically in accordance with the objective law, and can be used for the region climate data spatial informatization simulation. [Conclusion] The study provided scientific spatial basic data for the further study of ecological and vegetation in Hengduan Mountains.
基金supported by the National Natural Science Foundation of China(31800177,32170224,and U1802242)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB31000000)+2 种基金T-S.H.is also supported by the Youth Innovation Promotion Association CAS(2020391)China Scholarship Council(201804910061)CAS Light of West China Program.We acknowledge Ya-Long Guo at the Institute of Botany CAS for providing Capsella rubella seeds and revising the manuscript.
文摘Polyploids contribute substantially to plant evolution and biodiversity;however,the mechanisms by which they succeed are still unclear.According to the polyploid adaptation hypothesis,successful polyploids spread by repeated adaptive responses to new environments.Here,we tested this hypothesis using two tetraploid yellowcresses(Rorippa),the endemic Rorippa elata and the widespread Rorippa palustris,in the temperate biodiversity hotspot of the Hengduan Mountains.Speciation modes were resolved by phylogenetic modeling using 12 low-copy nuclear loci.Phylogeographical patterns were then examined using haplotypes phased from four plastid and ITS markers,coupled with historical niche reconstruction by ecological niche modeling.We inferred the time of hybrid origins for both species as the mid-Pleistocene,with shared glacial refugia within the southern Hengduan Mountains.Phylogeographic and ecological niche reconstruction indicated recurrent northward colonization by both species after speciation,possibly tracking denuded habitats created by glacial retreat during interglacial periods.Common garden experiment involving perennial R.elata conducted over two years revealed significant changes in fitness-related traits across source latitudes or altitudes,including latitudinal increases in survival rate and compactness of plant architecture,suggesting gradual adaptation during range expansion.These findings support the polyploid adaptation hypothesis and suggest that the spread of polyploids was aided by adaptive responses to environmental changes during the Pleistocene.Our results thus provide insight into the evolutionary success of polyploids in high-altitude environments.
基金provided by funds from the National Science Foundation of China (NSFC) to D. Q. RAO (NSFC-39570090)the National Science Foundation grant DEB-0103795 to the late Joseph B. SLOWINSKI and Peter FRITSCH+1 种基金the National Geographic Society Grant for Research and Exploration (7340-02)from the contributors to the California Academy of Sciences’ China Natural History Project
文摘A population of Japalura from Yunnan Province, China, previously assigned to Japalura splendida, is described as a new species. The new species has been recorded between 1 138–2 500 m in the Nu River drainage between the towns of Liuku and Binzhongluo, and on the lower western slopes of the Nushan and eastern slopes of the Goaligongshan. The new species can be distinguished from other species of Japalura, except J. dymondi, by the following combination of characters: exposed tympani, prominent dorso-lateral stripes, and small gular scales. It is very similar with but differs from J. dymondi by having smooth or feebly keeled dorsal head scales, three relatively enlarged spines on either side of the post-occiput area, strongly keeled and mucronate scales on occiput area and within the lateral stripes, back of arm and leg green, higher number of dorsal-ridge scales(DS) and fourth toe subdigital scales(T4S). A principal component analysis of body measurements of adult male specimens of the new species and J. dymondi showed principal component 1 loading highest for upper arm length, fourth toe length and snout to eye length and principal component 2 loading highest for head width, head length and fourth toe length.
基金supported by the National Natural Science Foundation of China (31670206, 31360049) to Zhi-Min Limajor Program of NSFC (grant 31590823, 31590820) to Hang Sun,NSFC (31370004, 31570213) to Jian-Wen Zhang
文摘The Hengduan Mountains region is a biodiversity hotspot. In this study, we report the karyotypes of 19 species(21 populations) of Asteraceae from this region, 14 of which are reported for the first time. We also examined polyploidy in Asteraceae plants and summarized karyotype data in the literature for 69 congeneric taxa. In these genera, there were five different ploidy levels in the region, though the most dominant was diploid(73.08%). There is no direct evidence that ploidy level and karyotype asymmetry are associated with the distribution of recorded Asteraceae species from the Hengduan Mountains. This suggests that polyploidy(26.92%) may not play an important role in the evolutionary history of these plants, even though, among these genera, the ratio of paleopolyploidy was high(46.15%).
基金Supported by the U. S. National Science Foundation, Grant No. DEB-0321846, and the National Natural Science Foundation of China, Grant No. 40332021.
文摘Perhaps no region on earth presents such a confusing array of place names as does the area made up of the former provinces of Kham and Amdo in historic Tibet (Xizang). Within these areas, cities, towns, villages, mountains, lakes and other geographic features have at least two names applied to them, one Tibetan, the other Chinese. Overlying this indigenous nomenclature are the names applied by outsiders, mostly Europeans, each of whom used their native language to transliterate the names they heard or read from Tibetan or Chinese script, and names in the languages of other ethnic minorities who live within the area. Adding to the confusion are the conflicting “standards” for transliterating Tibetan and Chinese names. To resolve the inconsistencies and uncertainties of place names in this region, a multilingual gazetteer and thesaurus was prepared. The gazetteer-thesaurus was compiled to be used as a tool for correlating the often radically different names assigned to a single place or feature and to provide the geographic coordinates for each. The impetus for this project was the need to assign geographic coordinates to plant specimens collected in the area since the latter part of the 19th century up until the advent and widespread use of Global Positioning System (GPS) receivers in the 1990s. Georeferencing specimens is necessary for plotting the historical distribution of species and for more completely understanding the information contained on specimen labels. Knowing the distribution of plants is important for answering phylogenetic questions, determining local and widespread biogeographical patterns, identifying areas of unusually high diversity or endemism, and determining areas in need of special protection. The value of such a gazetteer, however, extends well beyond the field of botany. It is intended to be of use to anyone with a desire to know the nomenclatural history of places in the area and for pinpointing with a fair degree of accuracy the location of each of those places.
基金supported by the National Natural Science Foundation of China (41801099)the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0307, 2019QZKK0301)。
文摘The Fraction of Absorbed Photosynthetically Active Radiation(FPAR) is an important indicator of the primary productivity of vegetation. FPAR is often used to estimate the assimilation of carbon dioxide in vegetation. Based on MOD15 A2 H/FPAR data product, the temporal and spatial variation characteristics and variation trend of FPAR in different vegetation types in 2001 to 2018 were analyzed in the Hengduan Mountains. The response of FPAR to climate change was investigated by using Pearson correlation analytical method and partial least squares regression analysis. Results showed that the FPAR in Hengduan Mountains presented an increasing trend with time. Spatially, it was high in the south and low in the north, and it also showed obvious vertical zonality by elevation gradient.The vegetation FPAR was found to be positively correlated with air temperature and sunshine duration but negatively correlated with precipitation. Partial least squares regression analysis showed that the influence of sunshine duration on vegetation FPAR in Hengduan Mountains was stronger than that of air temperature and precipitation.
文摘Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification andgeologic significance of whole-rock Rb-Sr isochrons as well as the factors influencing homogenization of theisotopic systems are discussed. Usually. there is no good linear correlation of isochrons for diorites andalkali-rich intrusive rocks (including alkaline rock and alkalic granite). But by means of the external isochron ofmonominerals from the rocks. isochrons with good linear correlation as well as ages and Sr initial ratios with ahigh confidence can be obtained. In order to obtain a satisfactory isochron, the discriminant parameters shouldbe calculated from the Rb/Sr ratios and estimated ages of samples. Only those that meet the requirements canbe used as the Rb-Sr isochrons. The quality of an isochron should be judged from three factors, i.e. correlationcoefficient. MSWD and homogenization degree.
基金Under the auspices of West Light Foundation of Chinese Academy of Sciences (No. Y000141001)Key Program ofNational Natural Science Foundation of China (No. 91025002)+1 种基金Program for Incubation of Specialists in Glaciology and Geocryology of National Natural Science Foundation of China (No. 11J0930003)National Natural Science Foundation of China (No. 40725001,30970492)
文摘Variations and trends in extreme climate events are more sensitive to climate change than the mean values,and so have received much attention.In this study,twelve indices of temperature extremes and 11 indices of precipitation extremes at 32 meteorological stations in Hengduan Mountains were examined for the period 1961-2008.The results reveal statistically significant increases in the temperature of the warmest and coldest nights and in the frequencies of extreme warm days and nights.Decreases of the diurnal temperature range and the numbers of frost days and ice days are statistically significant.Regional averages of growing season length also display the trends consistent and significant with warming.At a large proportion of the stations,patterns of temperature extremes are consistent with warming since 1961:warming trends in minimum temperature indices are greater than those relating to maximum temperature.As the center of the Shaluli Mountain,the warming magnitudes decrease from inner to outer.Changes in precipitation extremes is low:trends are difficult to detect against the larger inter-annual and decadal-scale variability of precipitation,and only the wet day precipitation and the regional trend in consecutive dry days are significant at the 0.05 level.It can be concluded that the variation of extreme precipitation events is not obvious in the Hengduan Mountains,however,the regional trends generally decrease from the south to the north.Overall,the spatial distribution of temporal changes of all extreme climate indices in the Hengduan Mountains illustrated here reflects the climatic complexity in mountainous regions.