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Key evidence of the role of desertification in protecting the underlying permafrost in the Qinghai-Tibet Plateau.

ABSTRACT: Previous research has shown that the temperature of underlying permafrost decreases after the ground surface is covered with sand. No significant conclusions have yet been drawn that explain why this happens, because the heat transfer mechanism effects of the sand layer on the underlying permafrost remain unclear. These mechanisms were studied in the present work. We found that the upward shortwave radiation flux of the Qinghai-Tibet Plateau ground surface with a sand layer covering was higher than that of the surface without sand; thus, the atmospheric heat reflected by the sand layer is greater than that reflected by the surface without sand. Therefore, the net radiation of the surface with the sand layer is lower than that of the surface without sand, which reduces the heat available to warm the sand layer. Because sand is both a porous medium and a weak pervious conductor with poor heat conductivity, less heat is conducted through the sand layer to the underground permafrost than in soil without the sand deposition layer. This phenomenon results in a decrease in the ground temperature of the permafrost under the sand layer, which plays a key role in protecting the permafrost.

SUBMITTER: Xie S

PROVIDER: S-EPMC4606803 | biostudies-other | 2015

REPOSITORIES: biostudies-other

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Qinghai-Tibet Plateau soil

Project description:Qinghai-Tibet Plateau soil

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Unexpectedly minor nitrous oxide emissions from fluvial networks draining permafrost catchments of the East Qinghai-Tibet Plateau.

Project description:Streams and rivers emit substantial amounts of nitrous oxide (N2O) and are therefore an essential component of global nitrogen (N) cycle. Permafrost soils store a large reservoir of dormant N that, upon thawing, can enter fluvial networks and partly degrade to N2O, yet the role of waterborne release of N2O in permafrost regions is unclear. Here we report N2O concentrations and fluxes during different seasons between 2016 and 2018 in four watersheds on the East Qinghai-Tibet Plateau. Thawing permafrost soils are known to emit N2O at a high rate, but permafrost rivers draining the East Qinghai-Tibet Plateau behave as unexpectedly minor sources of atmospheric N2O. Such low N2O fluxes are associated with low riverine dissolved inorganic N (DIN) after terrestrial plant uptake, unfavorable conditions for N2O generation via denitrification, and low N2O yield due to a small ratio of nitrite reductase: nitrous oxide reductase in these rivers. We estimate fluvial N2O emissions of 0.432 - 0.463 Gg N2O-N yr-1 from permafrost landscapes on the entire Qinghai-Tibet Plateau, which is marginal (~0.15%) given their areal contribution to global streams and rivers (0.7%). However, we suggest that these permafrost-affected rivers can shift from minor sources to strong emitters in the warmer future, likely giving rise to the permafrost non-carbon feedback that intensifies warming.

| S-EPMC8854393 | biostudies-literature

The effect of decreasing permafrost stability on ecosystem carbon in the northeastern margin of the Qinghai-Tibet Plateau.

Project description:The objective of this study is to investigate the effect of decreased permafrost stability on carbon storage of the alpine ecosystems in the northeastern margin of the Qinghai-Tibet Plateau. During July and August 2013, we selected 18 sites in five types of permafrost (stable, substable, transitional, unstable, and extremely unstable) regions. We measured aboveground phytomass carbon (APC) and soil respiration (SR), soil inorganic carbon (SIC), soil organic carbon (SOC), belowground phytomass carbon, and soil properties down to 50 cm at same types of soils and grasslands. The results indicated that ecosystem carbon in cold calcic soils first decreased and then increased as the permafrost stability declined. Overall, decreasing permafrost stability was expected to reduce ecosystem carbon in meadows, but it was not obvious in swamp meadows and steppes. APC decreased significantly, but SIC and SOC in steppes first decreased and then increased with declining permafrost stability. Soil clay fraction and soil moisture were the controls for site variations of ecosystem carbon. The spatial variations in SR were possibly controlled by soil moisture and precipitation. This meant that alpine ecosystems carbon reduction was strongly affected by permafrost degradation in meadows, but the effects were complex in swamp meadows and steppes.

| S-EPMC5843650 | biostudies-literature

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| S-EPMC8861457 | biostudies-literature

Importance of active layer freeze-thaw cycles on the riverine dissolved carbon export on the Qinghai-Tibet Plateau permafrost region.

Project description:The Qinghai-Tibet Plateau (QTP) is experiencing severe permafrost degradation, which can affect the hydrological and biogeochemical processes. Yet how the permafrost change affects riverine carbon export remains uncertain. Here, we investigated the seasonal variations of dissolved inorganic and organic carbon (DIC and DOC) during flow seasons in a watershed located in the central QTP permafrost region. The results showed that riverine DIC concentrations (27.81 ± 9.75 mg L-1) were much higher than DOC concentrations (6.57 ± 2.24 mg L-1). DIC and DOC fluxes were 3.95 and 0.94 g C m-2 year-1, respectively. DIC concentrations increased from initial thaw (May) to freeze period (October), while DOC concentrations remained relatively steady. Daily dissolved carbon concentrations were more closely correlated with baseflow than that with total runoff. Spatially, average DIC and DOC concentrations were positively correlated with vegetation coverage but negatively correlated with bare land coverage. DIC concentrations increased with the thawed and frozen depths due to increased soil interflow, more thaw-released carbon, more groundwater contribution, and possibly more carbonate weathering by soil CO2 formed carbonic acid. The DIC and DOC fluxes increased with thawed depth and decreased with frozen layer thickness. The seasonality of riverine dissolved carbon export was highly dependent on active layer thawing and freezing processes, which highlights the importance of changing permafrost for riverine carbon export. Future warming in the QTP permafrost region may alter the quantity and mechanisms of riverine carbon export.

| S-EPMC6585901 | biostudies-literature

Genetic evidence for subspecies differentiation of the Himalayan marmot, Marmota himalayana, in the Qinghai-Tibet Plateau.

Project description:The primary host of plague in the Qinghai-Tibet Plateau (QTP), China, is Marmota himalayana, which plays an essential role in the maintenance, transmission, and prevalence of plague. To achieve a more clear insight into the differentiation of M. himalayana, complete cytochrome b (cyt b) gene and 11 microsatellite loci were analyzed for a total of 423 individuals from 43 localities in the northeast of the QTP. Phylogenetic analyses with maximum likelihood and Bayesian inference methods showed that all derived haplotypes diverged into two primary well-supported monophyletic lineages, I and II, which corresponded to the referential sequences of two recognized subspecies, M. h. himalayana and M. h. robusta, respectively. The divergence between the two lineages was estimated to be at about 1.03 million years ago, nearly synchronously with the divergence between M. baibacina and M. kastschenkoi and much earlier than that between M. vancouverensis and M. caligata. Genetic structure analyses based on the microsatellite dataset detected significant admixture between the two lineages in the mixed region, which verified the intraspecies level of the differentiation between the two lineages. Our results for the first time demonstrated the coexistence of M. h. himalayana and M. h. robusta, and also, determined the distribution range of the two subspecies in the northeast of QTP. We provided fundamental information for more effective plague control in the QTP.

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Mosquitoes and mosquito-borne arboviruses in the Qinghai-Tibet Plateau--focused on the Qinghai area, China.

Project description:An investigation was conducted to identify the distribution of mosquitoes and mosquito-borne arboviruses in the Qinghai-Tibet Plateau, China from July to August in 2007. A total of 8,147 mosquitoes representing six species from three genera (Aedes, Culex, and Anopheles) were collected in three locations (Geermu city, altitude of 2,780 m; Xining city, 2,200 m; Minhe county, 1,700 m). Six virus isolates were obtained including Tahyna virus (TAHV), Liaoning virus, and Culex pipiens pallens Densovirus. A serosurvey showed immunoglobulin G antibodies by immunofluorescence assay (IFA) against TAHV in residents of all three locations. The IFA-positive human samples were confirmed by 90% plaque-reduction neutralization tests (PRNT(90)) against TAHV with titers ranging from 1:20 to 1:10,240. In addition, TAHV seropositive cows, sheep, and swine were found in these locations. This investigation represents the first isolation of TAHV from Ae. (Och.) detritus and the first evidence of TAHV infection in residents and livestock in the Qinghai-Tibet Plateau.

| S-EPMC2844569 | biostudies-literature

Plant Resource Availability of Medicinal Fritillaria Species in Traditional Producing Regions in Qinghai-Tibet Plateau.

Project description:The genus Fritillaria (Liliaceae) comprises of ~140 species of bulbous perennials, which are distributed in the temperate zone of the Northern Hemisphere. Fritillaria species have attracted much attention because of their commercial value, partly as ornamental plants but principally as a source of material for use in traditional medicine. The use of Fritillaria extracts is well established in some countries in Eastern Europe (e.g., Turkey), and Asia (e.g., China, Japan). In traditional Chinese medicine, the medicinal Fritillaria species is called Bulbus Fritillariae Cirrhosae (BFC), which has been used as a traditional medicine for thousands of years. However, to the best of our knowledge, there are no reports on resource investigation of plants of BFC in the last ten years. In this study, we chose 32 traditional producing regions in Qinghai-Tibet Plateau to perform an investigation on resource availability of BFC. In five sites we did not find any plants of BFC. Results show that the average number of the plants of BFC per quadrat in 26 sites was less than 7, and the average resource density was <22 mg/m2. Habitat types and plant morphology of BFC plants were recorded. Our investigation shows that the area for artificial cultivation of BFC is larger than 400 hm2 and productivity was higher than 180 t. In addition, the total alkaloid contents of samples from cultivated bases and plantations are higher than that from wild fields. This study suggests that the wild populations of BFC are still at the risk of depletion. Artificial cultivation of BFC might be an important way to resolve the current contradiction between resource protection and resource utilization. In addition, identifying the closest European relatives of the Fritillaria species used in traditional medicine may resolve this contradiction.

| S-EPMC5545572 | biostudies-other

Flower color polymorphism of a wild Iris on the Qinghai-Tibet plateau.

Project description:BackgroundFlower color plays a crucial role in attracting pollinators and facilitating environmental adaptation. Investigating the causes of flower color polymorphism and understanding their potential effects on both ecology and genetics can enhance our understanding of flower color polymorphism in wild plant.ResultsIn this study, we examined the differences of potential male and female fitness between purple- and yellow- flower individuals in Iris potaninii on the Qinghai-Tibet Plateau, and screened key genes and positively selective genes involved in flower color change. Our results showed that yellow flower exhibited a higher pollen-to-ovule ratio. Yellow flowers were derived from purple flowers due to the loss of anthocyanins, and F3H could be an essential gene affecting flower color variation though expression regulation and sequence polymorphism in this species. Furthermore, our findings suggest that genes positively selected in yellow-flowered I. potaninii might be involved in nucleotide excision repair and plant-pathogen interactions.ConclusionsThese results suggest that F3H induces the flower color variation of Iris potaninii, and the subsequent ecological and additive positive selection on yellow flowers may further enhance plant adaptations to alpine environments.

| S-EPMC10709947 | biostudies-literature

Ptilagrostis contracta (Stipeae, Poaceae), a New Species Endemic to Qinghai-Tibet Plateau.

Project description:A new species, Ptilagrostis contracta, endemic to Qinghai-Tibet Plateau is described and illustrated. It is distinguished from other species in Ptilagrostis by having contracted panicles, 1-geniculate awns with hairy columns and scabrous bristles and evenly pubescent lemmas. Evidence from lemma epidermal pattern, cytology and molecular phylogenetic analyses based on the nuclear ITS sequence data confirm its systematic position in Ptilagrostis.

| S-EPMC5218392 | biostudies-literature

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