Deserts Of China Research Articles

The microstructure, phase transformation and sinterability of desert sand

Desert sand has been widely used to manufacture paving materials, concrete, cement clinker, ceramics, glass, and bulk materials. It has different effects on the processing and properties of the materials from that of quartz sand, clay, and aggregates; however, the physicochemical characteristics of desert sand have not been deeply realized in term of the materialogy, bringing about much confusion in the manufacturing. In the present study, desert-sand samples were collected at different locations in the Hobq desert, a typical desert in China, their microstructure, phase composition, phase transformation, and sinterability were examined using X-ray diffraction (XRD), scanning electronic microscope (SEM), transmission electronic microscope (TEM), differential scanning calorimeter (DSC) techniques, as well as a sintering test. Results show that the sampling location had a little influence on the characteristics. Desert-sand granules were not uniform, which displayed variety of morphology and microstructure and some microcracks existed inside. They had a phase composition of α-quartz, amorphous SiO2, glass phase, and feldspars, some of them were with nano and submicron sizes. α-quartz was a dominant phase and had distorted crystal lattices. Four phase transformations successively occurred upon heating: α-quartz to β-quartz and further to β-tridymite, low-melting substances melt, and amorphous SiO2 and β-tridymite to β-cristobalite. Desert-sand powder compacts had an excellent self-sinterability, the densest bodies and the highest mechanical properties occurred when sintered at 1100 °C for 2 h. This information is beneficial to understand the mechanism and control the synthesis and properties of desert-sand materials.

Responses of feldspathic sandstone and sand-reconstituted soil C and N to freeze–thaw cycles

Abstract The Mu Us Desert in China is significantly affected by seasonal freeze–thaw processes. In order to evaluate the adaptation potential of reconstituted soil with different proportions of feldspathic sandstone and sand to extreme environment, the laboratory simulation freeze-thaw experiments was conducted to study the characteristics of soil C and N under freeze–thaw conditions. The results showed that the content of soil organic matter reached the peak after two cycles of freezing and thawing in T1, T2 and T3, compared to before freeze–thaw cycle, the soil organic matter content increased by 70, 55 and 59%. After ten cycles of freezing and thawing, the content of soil organic matter increased significantly in T2 and T3. After one cycle of freezing and thawing, soil nitrogen content reached the peak. After ten cycles of freeze–thaw cycle, compared to before freeze–thaw cycle, the contents of ammonium nitrogen increased by 10, 49 and 11%, and the contents of nitrate nitrogen increased by 14, 39 and 34% in T1, T2 and T3. In conclusion, short-term freeze–thaw cycles in the Mu Us Desert significantly increased the accumulation of soil carbon and nitrogen reconstructed by different ratios of feldspathic sandstone and sand, and T2 and T3 treatments had better retention performance on soil organic matter and nitrogen, which has a good adaptability to the extreme environment.

Characteristics of Optical Properties and Heating Rates of Dust Aerosol over Taklimakan Desert and Tibetan Plateau in China Based on CALIPSO and SBDART

The spatial and temporal distributions of dust aerosol and its radiative heating effect over Taklimakan Desert (TD) and Tibetan Plateau (TP) were analyzed using the CALIPSO aerosol products and the SBDART model during 2007–2020. The annual dust aerosol optical depths (DAOD at 532 nm) ranged from 0.266 to 0.318 over TD and 0.086 to 0.108 over TP, with means of 0.286 ± 0.015 and 0.097 ± 0.006, respectively. The regional mean DAODs of TD (TP) from spring to winter were 0.375 ± 0.020 (0.107 ± 0.010), 0.334 ± 0.028 (0.110 ± 0.010), 0.235 ± 0.026 (0.071 ± 0.008), and 0.212 ± 0.045 (0.083 ± 0.011), respectively. The maximal (minimal) seasonal DAOD of TD appeared in spring (winter), while that of TP appeared in summer (autumn). Although neither the annual nor the seasonal DAODs showed a statistically significant trend over both TD and TP, their yearly fluctuations were apparent, showing coefficients of variation of 0.053 and 0.065 over TD and TP, respectively. The profile of dust extinction coefficient (σD) showed the maximum in spring and summer over TD and TP, respectively. It showed a weak increasing trend of σD over both TD and TP in spring, but a decreasing trend in autumn. The dust of TD is concentrated within 1–4 km, where the annual averaged shortwave (SW) dust heating rates (DHRs) were larger than 2 K·day−1 from March to September. Over TP, the dust heating layer with SW DHR > 2 K·day−1 ranged from 3 to 4 km during March to June. The SW DHR was much larger in spring and summer than in the other two seasons over both regions, with the maximum in spring. A relatively strong dust heating layer with top >5 km appeared along the north slope of the TP, indicating an important energy transport channel from TD to TP, especially in spring and summer. It showed an increasing trend of the SW DHR over both TD and TP in spring and winter, but a decreasing trend in summer and autumn. Over TD, the most powerful heating appeared within 2–4 km, but the strength and the area of high-value DHR reduced from spring to winter. The highest SW DHR of TP appeared over the Qaidam Basin, acting as an important transmission channel of dust and its heating. For the columnar mean of lower than 10 km, the annual mean DHRs of TD and TP were 0.93 and 0.48 K⋅day−1, respectively. Although the DAOD and DHR of TP were both lower, its shortwave dust heating efficiency (DHE) was 1.7 times that of TD, which suggested that the same amount of dust imported to TP could generate a stronger heating effect than it did at the source.

What determines plant species diversity along the Modern Silk Road in the east?

As primary producers, plants provide food, oxygen, and other resources for global ecosystems, and should therefore be given priority in biodiversity protection. Most biodiversity research focuses on biodiversity hotspots, while biodiversity coldspots, such as deserts, are largely ignored. We propose that the factors shaping plant species diversity differ between biodiversity hot spots and cold spots, especially for desert ecosystems. To test this hypothesis, we investigated plant species diversity along the Modern Silk Road in the Northwest China desert, an area characterized by low precipitation, scarce vegetation, a limited number of species, and variable human activities. Surface soil was sampled from 144 plots, environmental DNA (eDNA) was extracted from soil samples, and seed plant species were identified using DNA metabarcoding technology. A total of 671 seed plant species were detected, which was more diverse than indicated by plot survey data. Plant species diversity gradually decreased from east to west along the Silk Road. In this area, temperature determines plant species diversity more than precipitation. Additionally, human activity has altered plant species diversity by introducing crops and invasive plants and eliminating environmentally adapted indigenous plants. Our results demonstrate the potential of eDNA metabarcoding technology for plant species diversity surveying. Desert plants have adapted to dry environments by relying on underground water or utilizing occasional rainfall as ephemerals, which are often not visible during surface surveys because of their short aboveground life cycle but can be detected with eDNA metabarcoding technology. Groundwater maintenance and human activity control are recommended for plant species diversity conservation and desertification control.

Atmospheric Vapor Impact on Desert Vegetation and Desert Ecohydrological System

The ability of plants to absorb unsaturated atmospheric water vapor is a controversial topic. To study how vegetation in arid areas survives under limited water resources, this study uses Tamarisk in the Ulan Buh Desert of China as an example. The in-situ observation of a newly designed Lysimeter and sap flow meter system were used to monitor the precipitation infiltration and the utilization efficiency of Tamarisk of atmospheric vapor. The results show that the annual precipitation of 84 mm in arid areas could still result in deep soil recharge (DSR) with a recharge rate of 5 mm/year. Furthermore, DSR is detectable even in the winter, and the 5-year average DSR was 5.77% of the annual precipitation. It appears that the small precipitation events are critically important for the survival of Tamarisk. When the atmospheric relative humidity reaches 70%, Tamarisk leaves can absorb the unsaturated atmospheric vapor, which accounts for 13.2% of the annual precipitation amount. To adapt to the arid environment, Tamarisk can harvest its water supply from several sources including atmospheric vapor and micro-precipitation events (whose precipitation is below the measurement limit of 0.2 mm of the precipitation gauge) and can still permit a certain amount of recharge to replenish the deep soil moisture. Such an ecohydrological dynamic is of great significance to desert vegetation.

Spatio-Temporal Patterns and Driving Forces of Desertification in Otindag Sandy Land, Inner Mongolia, China, in Recent 30 Years

Background: Desertification is one of the main obstacles to global sustainable development. Monitoring, evaluating and mastering its driving factors are very important for the prevention and control of desertification. As one of the largest deserts in China, the development of desertification in Otindag Sandy Land (OSL) resulted in the reduction in land productivity and serious ecological/environmental consequences. Although many ecological restoration projects have been carried out, the vegetation restoration of OSL and the impact mechanism of climate and human activities on desertification remain unclear. Methods: Taking OSL as the research area, this paper constructs the desertification index by using the remote sensing images and meteorological and socio-economic data, between 1986 and 2016, and analyzes the spatio-temporal evolution process and driving factors of desertification by using trend analysis and spearman rank correlation. Results: The results showed that: (1) Desertification in the OSL has fluctuated greatly during the past 30 years. Desertification recovered between 1986 and 1990, expanded and increased between 1990 and 2000, reduced between 2000 and 2004, developed rapidly between 2004 and 2007, and recovered again between 2007 and 2016; (2) The desertification of OSL is dominated by a non-significant change trend, accounting for 73.27%. In the significant change trend, the area of desertification rising trend is 20.32%, which is mainly located in the north and east, and the area of declining trend is 6.41%, which is mainly located in the southwest; (3) Desertification is the result of the superposition of climate and human activities. Climate change is the main influencing factor, followed by human activities, and the superposition effects of the two are spatio-temporal differences. Conclusions: These results shed light on the development of desertification in OSL and the relative importance and complex interrelationship between human activities and climate in regulating the process of desertification. Based on this, we suggest continuing to implement the ecological restoration policy and avoid the destruction of vegetation by large-scale animal husbandry in order to improve the situation of desertification.

Selection and evaluation of pseudo-invariant calibration sites in the Badain Jaran and Tengger Desert of China based on Sentinel satellite data

Selection and evaluation of pseudo-invariant calibration sites in the Badain Jaran and Tengger Desert of China based on Sentinel satellite data

The ecological uniqueness of plant communities and their determinants across the temperate deserts of China

The ecological uniqueness of plant communities and their determinants across the temperate deserts of China

Abandonment of ancient cities near the Salawusu River valley, China, triggered by stream capture

Several cities in the Salawusu River basin in the western Mu Su Desert of China were abandoned after the Yuan Dynasty (1271 to 1368 CE). Incisions of rivers caused by earth uplift coupled with a drier climate after the Yuan Dynasty have previously been attributed to such irreversible abandonments. Here we use geomorphological analyses, coupled with hydrological reconstructions to investigate the ancient stream patterns in the period leading up to the abandonments. We find that the abandonment of wells, the thermoluminescence age of which is about 640 years before present, in these cities coincided with a stream capture event that led to rapid river valley incision of up to 95 mm/year. We suggest that this stream piracy event lowered the water table in the area and triggered the abandonment of settlements, rather than a change to a drier climate as previously believed. We conclude that when considering environmental influences on archaeological records, geographic events must be considered in addition to climatic change.

Contrasting Regulators of the Onset and End of the Seed Release Phenology of a Temperate Desert Shrub Nitraria tangutorum

Seed release is crucial in the reproductive cycle of many desert plant species, but their responses to precipitation changes are still unclear. To clarify the response patterns, we conducted a long-term in situ water addition experiment with five treatments, including natural precipitation (control) plus an extra 25%, 50%, 75%, and 100% of the local mean annual precipitation (145 mm), in a temperate desert in northwestern China. Both the onset and end of the seed release phenophase of the locally dominant shrub, Nitraria tangutorum, were observed from 2012 to 2018. The results showed that both the onset and end time of seed release, especially the end time, were significantly affected by water addition treatment. On average, the end time of seed release was advanced by 3.9 d, 7.3 d, 10.8 d, and 3.8 d under +25%, +50%, +75%, and +100% water addition treatments, respectively, over the seven-year study, compared with the control. The changes in the onset time were relatively small (only several hours), and the duration of seed release was shortened by 4.0 d, 7.5 d, 10.8 d, and 2.0 d under +25%, +50%, +75%, and +100% water addition treatments, respectively. The onset and end time of seed release varied greatly between the years. Preceding fruit ripening and summer temperature jointly regulated the inter-annual variation of the onset time of seed release, while the cumulative summer precipitation played a key role in driving the inter-annual variation of the end time. The annual mean temperature controlled the inter-annual variation of the seed release duration, and these interactions were all non-linear.

Tensile properties of six desert shrub species in Hobq Desert, China

Abstract Desert shrubs are often planted to control wind erosion, land desertification, and desert expansion. Their motions of bending and vibration can absorb and disperse kinetic energy of wind, so as to protect the erodible surfaces close-by. According to continuum mechanics, the quantification of mechanical properties of shrubs is critical to understand their dynamic behaviors. In this study, the conventional tensile tests of six dominant desert shrub species’ stems mainly sampled in the Hobq Desert of China are performed. It is found that the tensile strength of Tamarix ramosissima and Hedysarum scoparium are larger than others, whereas Caragana korshinskii and Hippophae rhamnoides are more flexible. And then, it is theoretically and experimentally proved that the tensile strength and Young’s modulus of these desert shrubs both decrease with the increase of diameter.

Non-viviparous pre-dispersal seed germination in Amaranthaceae in the cold deserts of Central Asia

In the broad context of understanding the relationship between timing of seed germination and adaptation of a plant species to its habitat, the purpose of this study was to purse an observation of pre-dispersal seed germination of Salsola brachiata (Amaranthaceae) in late winter 2021 in the Amaranthaceae species-rich cold deserts in northwest China (Central Asia). We searched for pre-dispersal germination in species of Amaranthaceae growing in sand dunes (S), salt deserts (SD) and gravel deserts (GD). We examined 69 species in 155 populations in autumn 2021 and 52 species in 12 populations in early spring 2022. No seeds of any of the 69 species germinated on the mother plants in autumn 2021, while 30 of 52 species (57.7%) did so during snowmelt in early spring 2022. The rank order of species with few to many seeds germinated on the mother plants was annuals (66.7%) > small shrubs (23.3%) > small trees (6.7%) > shrubs (3.3%). The number of species in S, SD, and GD with pre-dispersal germinated seeds was 16 of 27 (59.3%), 15 of 31 (48.4%), and 15 of 30 (50.0%), respectively. The high species occurrence of pre-dispersal germination in early spring suggested that it might be adaptive in the unpredictable-rainfall growing-season environment of the cold deserts of Central Asia, a center of diversity of Amaranthaceae. However, preliminary studies on seedling/juvenile survival of S. brachiata showed that those from post-dispersal soil-germinated seeds had the best survival, suggesting that pre-dispersal seed germination may be maladaptive.

Green silk roads, partner state development, and environmental governance: Belt and road infrastructure on the Sino-East African frontier

ABSTRACT China's Belt and Road Initiative (BRI) is reorienting global development. Few scholars, however, query relationships between green silk road discourse, BRI infrastructure, partner state development goals, and environmental governance. This article details the roots of green silk road discourse in efforts to environmentally engineer China's desert landscapes. Much like large-scale nature-based infrastructure projects in China, BRI infrastructure projects abroad precipitate a range of socioeconomic and environmental outcomes. Through juxtaposing terrestrial infrastructure development in Ethiopia with maritime infrastructure development in Djibouti, the article demonstrates how different types of BRI infrastructure projects shape environmental governance and advance the development agendas of partner countries. Sugar plantations, roads, railways, and energy infrastructure in Ethiopia further Ethiopian state development plans while transforming Indigenous people's relations to their land and livelihoods. In Djibouti, port infrastructure and military bases figure centrally in strategic rentiership for the Djiboutian state with ancillary effects on fisheries and international trade. The article illustrates how relative articulations between East African central government development interests, environmental governance, and infrastructure are mediated by varieties of Chinese capital. The comparative analysis disrupts simplistic narratives of “win-win” partnerships and “China as threat” to partner state autonomy.

Decade-long unsustainable vegetation management practices increase macronutrient losses from the plant-soil system in the Taklamakan Desert

Arid ecosystems are characterized by low availability and mobility of soil nutrients and slow geochemical cycles. Management of native vegetation in such ecosystems for fuel, livestock grazing, and other agricultural activities (burning and cutting) may threaten semi-natural communities due to the changes in nutrient cycles and soil fertility. Alhagi sparsifolia is a dominant perennial legume in the Taklamakan Desert of northwestern China and has been used as fodder for livestock and plays a crucial ecological role in stabilizing dunes in the oasis-desert ecotone. We evaluated the effects of long-term (12 years) burning and cutting of plant biomass on the mineral nutrition of A. sparsifolia and associated soils at two depths (0–50 and 50–100 cm) in the field conditions following the block design experiment. We found that burning effects tended to be restricted to the topsoil (0–50 cm), and the concentration of many micro-and macronutrients was increased. Burning was associated with a decrease in plant nitrogen (N) and phosphorus (P) concentration, whereas concentrations of other micro-and macronutrients increased; overall, burning reduced foliar stocks of N, P, and potassium (K). Annual cutting elicited smaller increases in soil mineral (total sulfur, total P, calcium, magnesium, and available P and K) concentrations than burning, and soil enzymatic activities increased. There were contrasting response patterns of leaf N and P concentration and macro-and micronutrients between the two management approaches. Burning and cutting reduced leaf N and P concentrations, while changes in root and shoot N and P concentrations depended on treatments. Thus, burning and cutting of A. sparsifolia impact organ nutrient stoichiometry (increased losses of macronutrients from arid plant-soil ecosystems) and nutritional quality (for feeding livestock), particularly due to predicted rises in extreme climatic events under climate change that are expected to increase risks of soil erosion, however, impacts on native trophic webs remain unclear.

The responses to long-term nitrogen addition of soil bacterial, fungal, and archaeal communities in a desert ecosystem.

Nitrogen (N) deposition is a worldwide issue caused by human activity. Long-term deposition of N strongly influences plant productivity and community composition. However, it is still unclear how the microbial community responds to long-term N addition in a desert ecosystem. Therefore, a long-term experiment was conducted in the Gurbantonggut Desert in northwestern China in 2015. Four N addition rates, 0 (CK), 5 (N1), 20 (N2), and 80 (N3) kg N ha−1 yr.−1, were tested and the soil was sampled after 6 years of N addition. High-throughput sequencing (HTS) was used to analyze the soil microbial composition. The HTS results showed that N addition had no significant effect on the bacterial α-diversity and β-diversity (p > 0.05) but significantly reduced the archaeal β-diversity (p < 0.05). The fungal Chao1 and ACE indexes in the N2 treatment increased by 24.10 and 26.07%, respectively. In addition, N addition affected the bacterial and fungal community structures. For example, compared to CK, the relative abundance of Actinobacteria increased by 17.80%, and the relative abundance of Bacteroidetes was reduced by 44.46% under N3 treatment. Additionally, N addition also changed the bacterial and fungal community functions. The N3 treatment showed increased relative abundance of nitrate-reducing bacteria (27.06% higher than CK). The relative abundance of symbiotrophic fungi was increased in the N1 treatment (253.11% higher than CK). SOC and NH4+-N could explain 62% of the changes in the fungal community function. N addition can directly affect the bacterial community function or indirectly through NO3−-N. These results suggest that different microbial groups may have various responses to N addition. Compared with bacteria and fungi, the effect of N addition was less on the archaeal community. Meanwhile, N-mediated changes of the soil properties play an essential role in changes in the microbial community. The results in the present study provided a reliable basis for an understanding of how the microbial community in a desert ecosystem adapts to long-term N deposition.

Corrigendum: Ecologic service, economic benefits, and sustainability of the man-made ecosystem in the Taklamakan Desert

The longest artificial highway shelterbelt flowing across the Taklimakan desert was conducted in 2005. To ensure the sustainable development of the highway and shelterbelts, scholars have carried out a large number of studies on the shelterbelt since 1991. This review is based on an ongoing 30-year monitoring program from 1991-2021. We find that with the increase of shelterbelt age, some ecological and economic benefits gradually appear, such as saving transportation cost, promoting economic development in Southern Xinjiang, improving the sandy soil and microenvironment, and increasing the biodiversity. In the meanwhile, some adverse phenomena also exist, such as the high maintenance costs, water tables decreasing because of irrigation, threats of the protected species, pollution from pumping oil wells, and the potential damage from highway burying as sand dunes move forward. In view of these problems, some suggestions are as follows. Firstly, the science-policy sections of both the UNFCCC the UNCCD should pay special attention to providing research-based guidance for the international cooperation and coordination. Secondly, China government should provide the necessary funding to establish the 27th China desert observation and research station to ensure long-term monitoring, and slow the pace of construction on the desert highway to allow time to develop strategies that minimize the impact on wild animals. Thirdly, it is necessary to apply solar photovoltaic power in well irrigation and sand industry development. Fourthly, the sand-blocking belt of 10 m in width and 10 m away from the outside of upwind shelterbelt can be laid every five years in view of sand-buried roads. In short, the inter-agency collaboration and coordination are both essential to ensuring the success of sustainable development and management of the Taklimakan Desert Man-made Ecosystem.

Geochemical characteristics of surface aeolian sand in the Badain Jaran Desert, northwestern China: Implications for weathering, sedimentary processes and provenance

Knowledge of the provenance of the aeolian sand in deserts is crucial for revealing their development and the corresponding driving mechanisms. As the second-largest desert in China, the Badain Jaran Desert (BJD) has developed the tallest megadunes on Earth. However, the material source of these dunes, especially the provenance of different particle size fractions, is debated. Here, we address these issues using new geochemical data, consisting of the major, trace, and rare earth elemental signatures of different particle-size fractions of dune sands in the BJD and sediments from potential source areas. The source area sediments are from the rivers originating in the Qilian Mts., the Gobi regions between the Heihe River and the BJD, the piedmont of the Gobi-Altay Mts., and the alluvial fan of the Beida Mts. The results show that the dune sands of the BJD are mainly derived from felsic source rocks subjected to weak chemical weathering in the source area. The fine fraction (<63 μm) of the aeolian sand in the BJD has experienced some degree of sedimentary sorting and recycling, despite its mineralogical immaturity. Furthermore, comparison of the immobile trace elements and rare earth element (REE) ratios of the samples from the BJD with those from the potential source regions, together with the results of multidimensional scaling and principal component analysis, shows that the coarse fraction (63–250 μm) of the dune sand in the BJD originated mainly from fluvial and Gobi deposits eroded from the Qilian Mts.; whereas the fine fraction has a mixture of provenances, including the Qilian Mts. and the Gobi-Altay Mts., although the latter contribution is of limited significance.

A Temporary Broadband Seismic Array in the Largest Desert of China: TASTE

Abstract In early Permian, a mantle plume heated up the Tarim block and formed the Tarim large igneous province. It is an interesting phenomenon to explore the interaction between mantle plume and a thick continent lithosphere, because mantle plume has been proposed to be an important route of material and energy transportation in the earth. Currently, the Tarim block is surrounded by Tibetan plateau to its south edge and Tian Shan orogeny to its north edge. The combined effects of both mantle plume activity and plate tectonics should have significantly changed the structure and composition of the Tarim block because of its amalgamations in Neoproterozoic. Seismic imaging plays a key role on revealing the deep structure of the Earth, which could help unravel the questions mentioned before. However, the harsh natural environment in the central part of the Tarim basin, the Taklimakan desert—the largest desert in China—has seriously hampered the broadband seismological observation. From July 2017 to November 2019, the Institute of Geology and Geophysics, Chinese Academy of Sciences deployed a 2D broadband seismic array named the Tarim seismic Array for lithoSpheric signaTure of mantle plumE (TASTE) over the inner part of the Tarim basin with an averaged spacing of 60–70 km. The primary target of this project is to obtain a detailed lithospheric structure to resolve the possible lithospheric signatures of Permian mantle plume activity. Here we introduce the basic information of the TASTE network and the performance of these instruments by analyzing the background noise level. Preliminary results of receiver function and ambient noise analyses are also shown, which may suggest a thick sedimentary layer, as well as complicated crust and lithospheric feature.

N addition alters growth, non-structural carbohydrates, and C:N:P stoichiometry of Reaumuriasoongorica seedlings in Northwest China

Reaumuria soongorica is an important biological barrier for ecological protection in the Gobi Desert in northwestern China, where soil nitrogen availability is low. N deposition has recently increased significantly in Gobi Desert, and the responses of R. soongorica to N enrichment may become a problem for ecological restoration and protection. However, little is known about the effects of N addition on the biomass, non-structural carbohydrates (NSC), and carbon:nitrogen:phosphorus (C:N:P) stoichiometry of R. soongorica in this region. Here, we examined changes in biomass, NSC and C:N:P ratios of different organs of R. soongorica seedlings in four N addition treatments: 0 (N0), 4.6 (N1), 9.2 (N2), and 13.8 (N3) g m−2 year−1. N addition up to 9.2 g m−2 year−1 significantly increased the biomass of different organs, simultaneously increasing the belowground: aboveground ratio of R. soongorica seedlings. Root NSC concentrations significantly increased under all N addition treatments, but leaf and stem NSC concentrations only increased under the N1 and N2 addition treatments. Nitrogen addition enhanced the soluble sugar concentrations (SSC) of leaves and roots, and reduced starch concentrations (SC) of all organs. Stem and root N concentrations significantly increased under the N2 and N3 treatments, and leaf N concentrations only increased under the N3 treatment, but N addition had no significant effect on plant C and P concentrations. Leaf and stem C:N ratios decreased significantly under the N2 and N3 treatments, but root C:N decreased significantly in all N addition treatments. The N3 treatment significantly increased the N:P ratio of all organs. N addition significantly enhanced available N (AN), available P (AP) and total phosphorus (TP) in rhizosphere soil. Our results suggest that N addition alters the biomass, NSC, N concentrations, C:N and N:P ratios of all plant organs, but roots responded more strongly than stems or leaves to N addition, potentially allowing the plants to absorb more water from the arid soil in this region ensuring the survival of R. soongorica seedlings. Rhizosphere soil AP, AN and TP concentrations were important factors affecting the NSC concentrations and stoichiometric characteristics of R. soongorica.

Yeast Diversity in the Qaidam Basin Desert in China with the Description of Five New Yeast Species.

The Qaidam Basin is the highest and one of the largest and driest deserts on Earth. It is considered a mars analog area in China. In contrast to numerous studies concerning its geology, geophysical, and chemistry, relatively few studies have reported microbial diversity and distribution in this area. Here, we investigated culturable yeast diversity in the northeast Qaidam Basin. A total of 194 yeast strains were isolated, and 12 genera and 21 species were identified, among which 19 were basidiomycetous yeasts. Naganishia albida, N. adeliensis, and Filobasidium magnum were the three most dominant species and were distributed in thirteen samples from eight locations. Five new species (Filobasidium chaidanensis, Kondoa globosum, Symmetrospora salmoneus, Teunia nitrariae, and Vishniacozyma pseudodimennae) were found and described based on ITS and D1D2 gene loci together with phenotypic characteristics and physiochemical analysis. Representative strains from each species were chosen for the salt-tolerant test, in which species showed different responses to different levels of NaCl concentrations. Further, the strain from soil can adapt well to the higher salt stress compared to those from plants or lichens. Our study represents the first report of the yeast diversity in the Qaidam Basin, including five new species, and also provides further information on the halotolerance of yeasts from the saline environment in mars analog.