Southeastern Qinghai-Tibetan Plateau Research Articles

Last Deglaciation Climatic Fluctuation Record by the Palaeo-Daocheng Ice Cap, Southeastern Qinghai-Tibetan Plateau

The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau (QTP) is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides (TCN) 10Be and 26Al surface exposure dating was chosen to date the roche moutonnee, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap (p-DIC), southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of Bolling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.

Phylogeography of Rhodiola kirilowii (Crassulaceae): a story of Miocene divergence and quaternary expansion.

The evolution and current distribution of the Sino-Tibetan flora have been greatly affected by historical geological events, such as the uplift of the Qinghai-Tibetan Plateau (QTP), and Quaternary climatic oscillations. Rhodiola kirilowii, a perennial herb with its distribution ranging from the southeastern QTP and the Hengduan Mountains (HM) to adjacent northern China and central Asia, provides an excellent model to examine and disentangle the effect of both geological orogeny and climatic oscillation on the evolutionary history of species with such distribution patterns. We here conducted a phylogeographic study using sequences of two chloroplast fragments (trnL-F and trnS-G) and internal transcribed spacers in 29 populations of R. kirilowii. A total of 25 plastid haplotypes and 12 ITS ribotypes were found. Molecular clock estimation revealed deep divergence between the central Asian populations and other populations from the HM and northern China; this split occurred ca. 2.84 million year ago. The majority of populations from the mountains of northern China were dominated by a single haplotype or ribotype, while populations of the HM harbored both high genetic diversity and high haplotype diversity. This distribution pattern indicates that HM was either a diversification center or a refugium for R. kirilowii during the Quaternary climatic oscillations. The present distribution of this species on mountains in northern China may have resulted from a rapid glacial population expansion from the HM. This expansion was confirmed by the mismatch distribution analysis and negative Tajima's D and Fu's F S values, and was dated to ca. 168 thousand years ago. High genetic diversity and population differentiation in both plastid and ITS sequences were revealed; these imply restricted gene flow between populations. A distinct isolation-by-distance pattern was suggested by the Mantel test. Our results show that in old lineages, populations may harbour divergent genetic forms that are sufficient to maintain or even increase overall genetic diversity despite fragmentation and low within-population variation.

A 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau, China using tree-ring records

This paper presents a 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau using tree-ring records. Tree-ring samples were collected from the Hengduan Mountains in the southeastern part of the Qinghai-Tibet Plateau, China. A nearly 500-year chronology was developed using tree-ring width records. Correlation analysis shows moisture is the main factor limiting tree growth in this region. Ring-widths were significantly positively correlated with the Palmer Drought Severity Index (PDSI) and precipitation in many months. The highest correlation coefficient was found between the annual growth of trees and precipitation from the previous September to the current June (0.738). Based on this relationship, we reconstructed the precipitation history from 1509 to 2006. The reconstruction explains 54.4% (R 2adj =53.5%, N=49, F=56.12) of the actual precipitation variation during the calibration period (1958–2006). During the reliable period of the reconstruction (1549–2006), some low-frequency climate signals are included, indicating this region has been getting wetter in the last 20 years. The reconstruction documents six apparently dry and five pluvial periods and the 17th century dry period lasted longer than any other. When compared with other recent studies, this study and these earlier reconstructions show a similar trend in the variation of drought and pluvial. Further spatial correlation analysis confirms that the reconstructed precipitation adequately represents the rainfall history of the entire Hengduan Mountain area. The Multi-taper method, a type of spectral analysis, reveals that precipitation in this area had significant (P<0.01) spectral peaks at 3–5 a, 60 a and 79–85 a.

Phylogeography of Cyananthus delavayi (Campanulaceae) in Hengduan Mountains inferred from variation in nuclear and chloroplast DNA sequences

Abstract Phylogeographic studies on alpine plants endemic to the Hengduan Mountains of the southeastern Qinghai–Tibet Plateau are still limited in number. In this study, we used sequence variation of one nuclear gene (ncpGS, which encodes the chloroplastic glutamine synthetase) and in two chloroplast DNA segments to investigate the phylogeographic structure and population demographic history of Cyananthus delavayi, a narrow‐range species endemic to this region. We identified eight chlorotypes and 16 nuclear genotypes in a survey of 10 populations sampled throughout the range of the species. The results of both phylogenetic and network analyses suggested that the genealogical relationships of both chlorotypes and nuclear genotypes showed a clear geographical correlation. High total genetic diversity, low levels of within‐population diversity, and strong population differentiation (chloroplast DNA: hT= 0.827, hS= 0.087, NST= 0.899, GST= 0.895; nuclear DNA: hT= 0.910, hS= 0.348, NST= 0719, GST= 0.618) were identified. Based on the mismatch distribution analyses, no evidence of recent demographic population expansion was found for this species. Nested clade analyses of both chlorotypes and nuclear genotypes indicated that restricted gene flow resulting from isolation by distance and allopatric fragmentation were likely to have been the major processes that shaped their present‐day spatial distribution. Our dating of the genetic divergences between three major geographic lineages suggested that the largest glaciation of the early Quaternary developed in the Qinghai–Tibet Plateau and mountainous isolation may have together led to deep intraspecific vicariance within this species.

Predicaments and Protective Actions of Giant Panda Habitat of Baoxing County in Sichuan Province, China

The giant panda habitat of Baoxing County, located in the transition zone from Sichuan Basin to the edge of southeastern Qinghai-Tibet Plateau, is the critical and key ecological function areas. At present, the puzzled problems present that the whole ecological system was interrupted by ecological management from different local department policy and the long merits for protecting giant habitat was weaken by short-term economic profits from natural resources. Exploring marbles and constructing hydropower plants and the livelihood activities of residents in the world heritage protection zone threatened to the protection for giant panda habitats. The government and people have taken a series of measures in recent years to deal with conflict: setting up nature reserves, establishing ecological protection projects, speeding up adjustment of industrial structure and international cooperation. The development practice of Baoxing County over the years shows that it is a sustainable and effective measure to grow economy while simultaneously protecting the giant panda habitats through Integrated Ecosystem Management (IEM). However, giant panda protection is destined a protracted battle in economy development process.

CO2浓度升高和模拟氮沉降对青川箭竹叶营养质量的影响

通过研究大熊猫主食竹之一的青川箭竹(<em>Fargesia rufa </em>Yi)叶营养质量对CO₂浓度升高和模拟氮沉降的响应,预测在气候变化下箭竹和大熊猫之间的取食关系,以期为大熊猫的长久保护提供科学参考。利用人工环境控制生长室对青川箭竹幼苗进行了1个生长季节的大气CO₂浓度和施氮处理:(1)CON(对照,不添加N和环境CO₂浓度),(2)EC(环境CO₂浓度+350 μmol/mol、不添加N),(3)EN(添加5 g N m^-2 a^-1、环境CO₂浓度),(4)ECN(环境CO₂浓度+350 μmol/mol、添加5 g N m^-2 a^-1)。结果表明:EC处理对青川箭竹叶片的C含量无显著影响,但降低了叶片中N和P含量,从而导致C∶N增加,而N∶P没显著变化。另外,EC处理增加了叶片中可溶性蛋白、可溶性糖、淀粉、蔗糖和果糖的含量,但降低了木质素和纤维素含量。同时,EC也明显增加了叶片中防御物质单宁的含量。另一方面,EN处理显著降低了叶片中C的含量,并增加了N的含量,但没有改变P的含量,从而C∶N减小,而N∶P增加。EN显著提高了箭竹叶片可溶性蛋白、可溶性糖和木质素含量,减少了淀粉和纤维素,但对单宁无明显影响。ECN减少了箭竹叶的单宁和N、P的含量,但显著增加了叶的可溶性蛋白、可溶性糖、果糖、蔗糖和淀粉含量。大气CO₂浓度升高和氮沉降对叶的N、单宁、可溶性糖和淀粉含量具有显著的交互作用。在未来气候变化情景下,箭竹叶营养质量提高将可能影响叶的生物化学过程以及箭竹-大熊猫之间的取食关系。;Rising atmospheric carbon dioxide (CO₂) levels and increasing nitrogen deposition resulting from human activities have the potential to alter leaf nutrient quality and consequently alter plant/herbivore interactions.<em> Fargesia rufa</em> (Poaceae: Bambusoideae) is an important dietary bamboo for endangered giant pandas and is very vulnerable to climate change because it is one of the most widely distributed understory plants in subalpine coniferous forests in the southeastern Qinghai-Tibetan Plateau of China. Elevated CO₂ and nitrogen deposition will lead to change in the nutrient quality of <em>F. rufa</em> leaves, which could influence the growth and fecundity of giant pandas. Thus, understanding how elevated CO₂ and nitrogen deposition might change the nutritional quality and chemical defenses of<em> F. rufa</em> is an essential first step in predicting how giant pandas will respond to this component of climate change. However, there have been no studies on this aspect of <em>F. rufa</em> biology. The objects of this study were to (1) determine the effects of elevated CO₂ on the nutritive quality of <em>F. rufa</em>; (2) examine the effects of nitrogen on the quality of <em>F. rufa</em>; and (3) determine whether nitrogen alters the effects of elevated CO₂ on the foliar quality of bamboo. For this purpose, 30 seedlings were grown in each of six environmentally-controlled chambers for one growing season under the following conditions: control (CON; ambient CO₂concentration and N level), elevated CO₂ (EC; ambient CO₂ concentration + 350 μmol/mol, ambient N), extra N (EN; 5 g N m^-2 a^-1, ambient CO₂ concentration), and a combined treatment with both elevated CO₂ and extra N (ECN; ambient CO₂ concentration + 350 μmol/mol, 5 g N m^-2 a^-1). Leaves were analyzed for concentrations of carbon (C), nitrogen (N), phosphorus (P), soluble sugars, fructose, sucrose, lignin, cellulose, and C-based defensive compounds (tannins). Compared with CON, the EC treatment did not affect C concentration in leaves but led to a decline in N, P, and C∶N ratio, as well as lower cellulose and lignin levels in leaves. Also, EC induced an increase in the contents of soluble sugars, fructose, sucrose, soluble protein, and tannin. On the other hand, the addition of N tended to reduce C, C∶N ratio, starch, and cellulose contents in leaves. Leaf N, soluble sugar, soluble protein, and lignin contents were lower in treatments to which N was added than in treatments without additional N. Tannin and P in leaves tended not to change with the addition of N. The combined effects of elevated CO₂ and N on C, tannin, soluble sugars, and starch contents were significant. Although negative effects of elevated CO₂ on leaf nutrient quality in <em>F. rufa</em> were observed, the interaction of elevated CO₂and N appeared to be sufficient to actually improve leaf nutrient quality, indicating that climate change will likely impact not only the biochemical processes of <em>F. rufa</em> leaves but also the plant-giant panda interaction.

RAPD analysis of genetic diversity and population structure of Elymus sibiricus (Poaceae) native to the southeastern Qinghai-Tibet Plateau, China

Genetic diversity of Elymus sibiricus (Poaceae) was examined in eight populations from the southeast Qinghai-Tibet Plateau. We detected 291 RAPD polymorphic loci in 93 samples. The percentage of polymorphic bands (PPB) was 79%. Genetic diversity (H(E)) was 0.264, effective number of alleles (N(E)) was 1.444, Shannon's information index (H(O)) was 0.398, and expected Bayesian heterozygosity (H(B)) was 0.371. At the population level, PPB = 51%, N(E) = 1.306, H(E) = 0.176, I = 0.263, and H(B) = 0.247. A high level of genetic differentiation was detected based on Nei's genetic diversity analysis (G(ST) = 32.0%), Shannon's index analysis (33.7%), and the Bayesian method (θ(B) = 33.5%). The partitioning of molecular variance by AMOVA demonstrated significant genetic differentiation within populations (60%) and among populations (40%). The average number of individuals exchanged between populations per generation (N(m)) was 1.06. The populations were found to share high levels of genetic identity. No significant correlation was found between geographic distance and pairwise genetic distance (r = 0.7539, P = 0.9996). Correlation analysis revealed a significant correlation (r = 0.762) between RAPD H(E) found in this study and ISSR H(E) values from a previous study.

Postbreeding Movement and Habitat Use of the Plateau Brown Frog, Rana kukunoris, in a High-Elevation Wetland

We studied the movement patterns and habitat selection of 33 radio-tagged Plateau Brown Frogs (Rana kukunoris) in the Zoige Alpine Wetland in southeastern Qinghai-Tibet plateau. Our goals were to (1) understand postbreeding movement patterns of R. kukunoris; (2) describe microhabitat use, with special reference to use of small mammal burrows; (3) test for movement pattern and microhabitat use differences between sexes and between seasons; and (4) provide a preliminary description of overwintering sites. We found no differences in movement patterns between sexes in R. kukunoris, however, directional movement trends differed between habitats. Male and female R. kukunoris showed similar microhabitat selection with regard to air temperature, relative humidity, and vegetation height. Although males used mammal burrows more frequently than females at one study site, BaiHua, both sexes used these microhabitats frequently during their movements. Overwintering sites of R. kukunoris were characterized by year-round flowing water. Results from this study will assist in making decisions about conservation and land protection for this species.

English

&nbsp; &nbsp; A molecular investigation on the species of&nbsp;Populus&nbsp;belonging to sectionTacamahaca&nbsp;was undertaken with the aim of inferring genetic relationships within the section. The ISSR and cpDNA RFLP-based UPGMA analyses were performed for seven&nbsp;Populus&nbsp;species, with 50 specimens representing 10 accessions from southeastern Qinghai-Tibetan Plateau, China. The results provided molecular evidence suggesting that&nbsp;Populus schneideri&nbsp;is highly genetically similar toPopulus kangdingensis, as also indicated by previous studies with respect to their morphological characters. Similarly, the combination of cpSSR and nuclear SSR analyses showed that&nbsp;Populus trinervis&nbsp;and&nbsp;Populus simonii&nbsp;have a close genetic affinity, indicating their closed sister relationships. Although&nbsp;Populus yunnanensisis distinct from the other species based on nuclear ISSR analysis; it formed a clade with&nbsp;P. simonii&nbsp;and&nbsp;P. trinervis. This reflects similar maternal phylogeny among the three species. In addition, the cluster analyses clearly showed a close relationship among accessions of the same species and suggested monophyly inPopulus przewalskii&nbsp;and&nbsp;Populus cathayana. Our results demonstrated that the combination of cpDNA-RFLP and ISSR molecular markers enables a clear estimation of genetic relationships among&nbsp;Populus&nbsp;species and they provided information for preliminary conclusions that will be helpful in guiding future research. &nbsp; Key words:&nbsp;Populus, section&nbsp;Tacamahaca, genetic relationships. &nbsp;

Effects of enhanced UV-B radiation on growth and photosynthetic responses of four species of seedlings in subalpine forests of the eastern Tibet plateau

We assessed the influence of enhanced UV-B radiation on growth, root morphology, leaf morphology and anatomy, pigment concentrations and gas exchange of seedlings of four tree species ( Abies faxoniana, Acer mono, Picea asperata and Swida hemsleyi) from the southeastern Qinghai-Tibetan Plateau of China. Potted seedlings were exposed outdoors in Sichuan Province, China to two levels of UV-B (ambient UV-B, 11.02 KJ m −2 day −1; and enhanced UV-B, 14.33 KJ m −2 day −1). Exposure to enhanced UV-B radiation had significant effects on seedling growth and morphological and photosynthetic traits of the four species. Total and belowground biomass was lower in seedlings exposed to enhanced UV-B radiation in all four species. Concentrations of photosynthetic pigments (Chl (a + b)) and UV-B-absorbing compounds in the leaves of all four species was lower in seedlings exposed to enhanced UV-B radiation, but the Chl a/b ratio was not affected. Enhanced UV-B markedly reduced the net photosynthetic rate and increased the intercellular CO 2 concentration in the four species. Differences in stomatal conductance to water vapor were observed in all four species. Responses differed among the four species. Generally, exposure to enhanced UV-B radiation led to shrinkage and curling of leaves in A. mono and S. hemsleyi seedlings, and reduced the leaf number and mass in A. mono seedlings. Exposure to enhanced UV-B radiation markedly reduced the palisade tissue thickness in A. mono leaves but led to thicker leaves in S. hemsleyi seedlings. These results imply that broad-leaved tree seedlings were more sensitive to enhanced UV-B radiation than conifer seedlings.

Phylogeography of Potentilla fruticosa (Rosaceae) in the Qinghai-Tibetan Plateau revisited: a reappraisal and new insights

Background: Most empirical studies to date have suggested that alpine plants in the central Qinghai-Tibetan Plateau (QTP) originated from the south-eastern QTP. However, previous phylogeographcial analysis of Potentilla fruticosa suggested that it diversified in the central QTP, which has also been assumed to have been a glacial refugium, and expanded to the north-eastern regions during the mid-Holocene period. Aim: We reappraise this claim in the light of information acquired from sampling, haplotyping and analysing additional populations. Methods: We sequenced the chloroplast trnT-L intergenic spacer of 346 individuals collected from 52 populations. We reconstructed phylogenetic relationships among haplotypes through Bayesian and Network analysis, and used several methods for demographic analysis. Results: Some common and highly divergent haplotypes were distributed in the central, western and south-eastern QTP. Mismatch and other population genetic analyses applied to our data suggested that a distinct range expansion had occurred between approximately 30,000 and 325,000 years ago (kya). Conclusions: Besides the possible postglacial expansion in the north-eastern QTP, our results further suggested that the range of the species radically expanded across the whole Plateau before the last glacial maximum (around 18 kya) and the south-eastern, western and central QTP regions had together provided important refugia during recent glacial stages. These findings, in contrast to the previous conclusions, highlight the importance of adequate sampling strategies in phylogeographical studies.

Plant recolonization in the Himalaya from the southeastern Qinghai-Tibetan Plateau: Geographical isolation contributed to high population differentiation

The Himalaya–Hengduan Mountains region (HHM) in the southern and southeastern Qinghai-Tibetan Plateau (QTP) is considered an important reservoir and a differentiation center for temperate and alpine plants in the Cenozoic. To reveal how plants responded to the Quaternary climatic oscillations in the QTP, the phylogeographical histories of a few subalpine and alpine plants have been investigated, but nearly all studies used only uniparentally inherited cytoplasmic DNA markers, and only a couple of them included sampling from the Himalaya. In this study, range-wide genetic variation of the Himalayan hemlock ( Tsuga dumosa), an important forest species in the HHM, was surveyed using DNA markers from three genomes. All markers revealed genetic depauperation in the Himalaya and richness in the Hengduan Mountains populations. Surprisingly, population differentiation of this wind-pollinated conifer is very high in all three genomes, with few common and many private nuclear gene alleles. These results, together with fossil evidence, clearly indicate that T. dumosa recolonized the Himalaya from the Hengduan Mountains before the Last Glacial Maximum (LGM), accompanied with strong founder effects, and the influence of the earlier glaciations on demographic histories of the QTP plants could be much stronger than that of the LGM. The strong population differentiation in T. dumosa could be attributed to restricted gene flow caused by the complicated topography in the HHM that formed during the uplift of the QTP, and thus sheds lights on the importance of geographical isolation in the development of high plant species diversity in this biodiversity hotspot.

Spatial variability of soil carbon, nitrogen, and phosphorus content and storage in an alpine wetland in the Qinghai - Tibet Plateau, China

This study considers the spatial variability of soil organic carbon, nitrogen, and phosphorus storage in a drained alpine wetland and the possible relationships with soil properties. Top 0–0.30 m soil samples were collected in a typical alpine wetland in the south-eastern Qinghai–Tibet plateau using grid sampling. There was high spatial variability for soil organic carbon density (SOCD), soil total nitrogen density (STND), and soil total phosphorous density (STPD) in the drained alpine wetland. Spherical models best described the structure of the semivariograms for SOCD and STPD, and an exponential model for STND, with the range parameter of &lt;4 m. Similar spatial distribution with lower or higher patches of C, N, and P storage were observed. SOCD, STND, and STPD were significantly negatively correlated with soil moisture (P &lt; 0.01), and significantly positively correlated with bulk density (P &lt; 0.01). However, no significant correlations were observed between SOCD, STND, and STPD and soil pH values. Wetland drainage might lead to higher C, N, and P densities in top 0.30 m soils due to peat compaction; thus, it is necessary to incorporate water table fluctuations or the whole depth of peat layers to estimating precisely C, N and P storage.

Molecular phylogeography of alpine plant Metagentiana striata (Gentianaceae)

Herbaceous plants have a short life cycle and are sensitive to environmental changes. Thus, they may serve as good models to elucidate historical processes of plant populations since Quaternary glaciations. Molecular phylogeographic analysis is a powerful tool to reveal the population history of plants and animals. To understand the geographic history of alpine plants in the Qinghai-Tibet Plateau, which is still poorly known, we surveyed sequence variation of the chloroplast DNA (cpDNA) noncoding fragment trnH (GUG)-psbA intergenic spacer throughout the range of Metagentiana striata (Maxim.) T. N. Ho, S. W. Liu & S. L. Chen, an annual and herbaceous alpine plant in the Qinghai-Tibet Plateau and adjacent areas. Seven haplotypes were detected by analyzing 155 individuals from 13 populations of this species. One haplotype (A) was common and widespread, and three haplotypes (E, F and G) were unique in their populations. The center of haplotype diversity is located in the Hengduan Mountains of southeastern Qinghai-Tibet Plateau, with 2-3 haplotypes present in each of four populations. In populations from the northeastern and eastern Qinghai-Tibet Plateau as well as from adjacent regions, however, only a single haplotype was found in each population, with different populations having different haplotypes. An analysis of molecular variance (AMOVA) for populations of M striata showed that the genetic variation mainly resided among populations (73.05%), and the estimates of interpopulation differentiation were very high (G(ST)=0.805, F(ST)=0.731, N(ST)=0.859). Further, a significant phylogeographic structure was present (N(ST) > G(ST), P<0.05) whereas the value of average gene flow was low (N(m)=0.184) in the entire geographical range. Along with the nested clade analysis (NCA), our results suggested that the Hengduan Mountains of southeastern Qinghai-Tibet Plateau served as a possible refugium during the Quaternary glaciations, and the interglacial or post-glacial range expansion by plants from the refugium followed by allopatric and past fragmentation shaped the present distribution patterns of haplotypes and populations.

Population Genetic Survey of Populus cathayana Originating From Southeastern Qinghai-Tibetan Plateau of China Based on SSR Markers

AbstractIn this study, the genetic diversity of Populus cathayana Rehd was investigated using microsatellite markers. In a total of 150 individuals collected from six natural populations in the southeastern part of the Qinghai-Tibetan Plateau in China, a high level of microsatellite polymorphism was detected. At the seven investigated microsatellite loci, the number of alleles per locus ranged from 5 to 16, with a mean of 11.3, the observed heterozygosities across populations ranged from 0.408 to 0.986, with a mean of 0.792, and the expected heterozygosities across populations ranged from 0.511 to 0.891, with a mean of 0.802. The proportion of genetic differentiation among populations accounted for 37.3% of the whole genetic diversity. The presence of such a high level of genetic diversity could be attributed to the features of the species and the habitats where the sampled populations occur: The southeastern part of the Qinghai-Tibetan Plateau is regarded as the natural distribution and variation center of the genus Populus in China. Variation in environmental conditions and selection pressures in different populations, and topographic dispersal barriers could be factors associated with the high level of genetic differentiation found among populations. The populations possessed significant heterozygosity excesses, which may be due to extensive population mixing at the local scale. The cluster analysis showed that the populations are not strictly grouped according to their geographic distances but the habitat characteristics also influence the divergence pattern. In addition, we suggest that population SHY should be regarded as an ecologically divergent species of P. cathayana.

Genetic diversity of populus cathayana Rehd populations in southwestern china revealed by ISSR markers

As a native species to China, Populus cathayana Rehd is well-adapted to the wet and cold environments where it occurs. It is considered to be an important reforestation species in western China. In the present study, we surveyed the level of genetic variation and the pattern of genetic structure in seven natural populations of P. cathayana, originating from the southeastern Qinghai-Tibetan Plateau of China, by using ISSR (inter-simple sequence repeats) markers. Based on eight primers, 158 clear and reproducible DNA fragments were generated, of which 156 (98.7%) were polymorphic. The average value of Nei's gene diversity ( h) equaled 0.331. The coefficient of genetic differentiation ( G ST) equaled 0.477, which means that 47.7% of the total molecular variance existed among populations. Such a high level of divergence present among populations may be caused by the complex topography and variable climatic conditions present in the southeastern Qinghai-Tibetan Plateau which effectively restrict gene flow. Moreover, there is a lack of significant association between genetic and geographical distances ( r = 0.3122, P > 0.05) in the populations of P. cathayana. The application of a novel method, which combines geographical coordinates and genetic differentiation to detect barriers for gene flow, allowed us to identify two zones of lowered gene flow. The ISSR method used in the present genetic fingerprinting-based study proved to be an effective high-resolution tool for identifying patterns of genetic variation present in forest trees. In the case of P. cathayana, such information is greatly needed for planning conservation genetic actions to ensure the maintenance of appropriate levels of genetic variation.