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Analysis of structural characteristics and spatial distribution of the national intangible cultural heritage in China and its policy implications
BaiCui Xu,JingHu Pan
Sciences in Cold and Arid Regions    2019, 11 (5): 389-406.   DOI: 10.3724/SP.J.1226.2019.00389.
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Based on an investigation of four published batches listing 3,140 national intangible cultural heritage (ICH) projects in China and using GIS and some quantitative analysis methods, the spatial structure was investigated and the characteristics and distribution discussed. The distribution of ICHs in China is agglomerative and spatially dependent. From the view of ICH type, each type is distributed in different places, for different reasons, with history being the most important one we found. Nationwide, high-density cores are located in the Beijing-Tianjin-Hebei region and the Yangtze River Delta region. High densities of ICH are concentrated in flat, water-rich regions where broad-leaved forests dominate plains and low mountain areas—areas that have fertile soil, pleasant weather, a long history of culture, ethnic agglomeration, and development. This paper suggests that development of the ICH should be based on discovering unknown items, to break the existing pattern of strong cohesion and high density, and to seek a balanced development of the whole.

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A concise overview on historical black carbon in ice cores and remote lake sediments in the northern hemisphere
Poonam Thapa,JianZhong Xu,Bigyan Neupane
Sciences in Cold and Arid Regions    2021, 13 (3): 179-194.   DOI: 10.3724/SP.J.1226.2021.20055.
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Black Carbon (BC), as a driver of environmental change, could significantly impact the snow by accelerating melting and decreasing albedo. Systematic documentation of BC studies is crucial for a better understanding of its spatial and temporal trends. This study reviewed the BC studies in the ice core and remote lake sediments and their sources in the northern hemisphere. The literature surveyed points to around 2.9 to 3.7 times increase of BC in the European Alps and up to a three-fold increase of BC in the Himalayan-Tibetan Plateau (HTP) after the onset of industrialization in Europe and Asia, respectively. BC concentration from Greenland ice core showed seven times increase with an interrupted trend after 1950's. South Asian emissions were dominant in the HTP along with a contribution from the Middle East, whereas Western European and local emissions were responsible for the change in BC concentration in the European Alps. In the Arctic, contributions from North America, Europe and Asia persisted. Similarly, a historical reconstruction of lake sediments records demonstrates the effects of emissions from long-range transport, sediment focusing, local anthropogenic activities, precipitation and total input of flux on the BC concentration.

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Discussion on pile axial load test methods and their applicability in cold regions
JiaWei Gao,Ji Chen,Xin Hou,QiHang Mei,YongHeng Liu
Sciences in Cold and Arid Regions    2022, 14 (4): 267-281.   DOI: 10.1016/j.rcar.2022.09.005.
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The measurement of pile axial load is of great significance to determining pile foundation design parameters such as skin friction and end bearing capacity and analyzing load transfer mechanisms. Affected by the temperature and ice content of frozen ground, the interface contact relationship between pile foundation and frozen soil is complicated, making pile axial load measurements more uncertain than that in non-frozen ground. Therefore, it is necessary to gain an in-depth understanding of the current pile axial load test methods. Four methods are systematically reviewed: vibrating wire sensors, strain gauges, sliding micrometers, and optical fiber strain sensors. At the same time, the applicability of the four test methods in frozen soil regions is discussed in detail. The first two methods are mature and commonly used. The sliding micrometer is only suitable for short-term measurement. While the Fiber Bragg grating (FBG) strain gauge meets the monitoring requirements, the Brillouin optical time-domain reflectometer (BOTDR) needs further verification. This paper aims to provide a technical reference for selecting and applying different methods in the pile axial load test for the stability study and bearing capacity assessment of pile foundations in cold regions.

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Qualitative and quantitative phytochemical analysis of selected mosses with different alcoholic solvents
Kehinde O. Olasoji,Amos M. Makinde,Bolajoko A. Akinpelu,Musibau O. Isa
Sciences in Cold and Arid Regions    2019, 11 (5): 382-388.   DOI: 10.3724/SP.J.1226.2019.00382.
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This study was conducted to investigate the qualitative and quantitative phytochemical content of the crude extracts of Archidium ohioense, Pelekium gratum, and Hyophila involuta with different alcoholic solvents (ethanol, methanol, Seaman's Schnapps, fresh oil-palm wine, and fresh Raffia-palm wine). The mosses were collected from their natural populations on the central campus of the Obafemi Awolowo University, Ile-Ife, Nigeria. The yield of the extracts was weighed for all the solvents, and the qualitative and quantitative evaluations of the extracts were carried out using standard methods. The results of phytochemical analysis of the crude extracts from the mosses showed the presence of saponins, cardiac glycosides, triterpenes, alkaloids, flavonoids, and steroids. The quantitative phytochemical analysis of the crude extracts showed that ethanolic extracts of Hyophila involuta had the highest flavonoid content (288.37±0.10 mg RE/g), and Raffia-palm-wine extracts of Hyophila involuta had the highest saponin content (224.70±0.02 mg/g), while the methanolic extract of Archidium ohioense had the highest cardiac glycosides content (63.71±0.14 mg/g), and the Raffia-palm wine extract of Hyophila involuta had the highest alkaloids content (102.50±0.12 mg/g). Raffia- and oil-palm wines were observed to be the most effective solvents for all the mosses studied, followed by Seaman's Schnapp, while methanol and ethanol were less effective. The study concluded that the extracts of the mosses studied contain pharmacologically active constituents that can be used for therapeutic purposes.

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Soil freezing process and different expressions for the soil-freezing characteristic curve
JunPing Ren, Sai K. Vanapalli, Zhong Han
Sciences in Cold and Arid Regions    2017, 9 (3): 221-228.   DOI: 10.3724/SP.J.1226.2017.00221
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The soil-freezing characteristic curve (SFCC), which represents the relationship between unfrozen water content and sub-freezing temperature (or suction at ice-water interface) in a freezing soil, can be used for understanding the transportation of heat, water, and solute in frozen soils. In this paper, the soil freezing process and the similarity between the SFCC of saturated frozen soil and soil-water characteristic curve (SWCC) of unfrozen unsaturated soil are reviewed. Based on similar characteristics between SWCC and SFCC, a conceptual SFCC is drawn for illustrating the main features of soil freezing and thawing processes. Various SFCC expressions from the literature are summarized. Four widely used expressions (i.e., power relationship, exponential relationship, van Genuchten 1980 equation and Fredlund and Xing 1994 equation) are evaluated using published experimental data on four different soils (i.e., sandy loam, silt, clay, and saline silt). Results show that the exponential relationship and van Genuchten (1980) equation are more suitable for sandy soils. The simple power relationship can be used to reasonably best-fit the SFCC for soils with different particle sizes; however, it exhibits limitations when fitting the saline silt data. The Fredlund and Xing (1994) equation is suitable for fitting the SFCCs for all soils studied in this paper.
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Light-absorbing impurities on Keqikaer Glacier in western Tien Shan: concentrations and potential impact on albedo reduction
YuLan Zhang, ShiChang Kang, Min Xu, Michael Sprenger, TanGuang Gao, ZhiYuan Cong, ChaoLiu Li, JunMing Guo, ZhiQiang Xu, Yang Li, Gang Li, XiaoFei Li, YaJun Liu, HaiDong Han
Sciences in Cold and Arid Regions    2017, 9 (2): 97-111.   DOI: 10.3724/SP.J.1226.2017.00097
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Light-absorbing impurities on glaciers are important factors that influence glacial surface albedo and accelerate glacier melt. In this study, the quantity of light-absorbing impurities on Keqikaer Glacier in western Tien Shan, Central Asia, was measured. We found that the average concentrations of black carbon was 2,180 ng/g, with a range from 250 ng/g to more than 10,000 ng/g. The average concentrations of organic carbon and mineral dust were 1,738 ng/g and 194 μg/g, respectively. Based on simulations performed with the Snow Ice Aerosol Radiative model simulations, black carbon and dust are responsible for approximately 64% and 9%, respectively, of the albedo reduction, and are associated with instantaneous radiative forcing of 323.18 W/m2 (ranging from 142.16 to 619.25 W/m2) and 24.05 W/m2 (ranging from 0.15 to 69.77 W/m2), respectively. For different scenarios, the albedo and radiative forcing effect of black carbon is considerably greater than that of dust. The estimated radiative forcing at Keqikaer Glacier is higher than most similar values estimated by previous studies on the Tibetan Plateau, perhaps as a result of black carbon enrichment by melt scavenging. Light-absorbing impurities deposited on Keqikaer Glacier appear to mainly originate from central Asia, Siberia, western China (including the Taklimakan Desert) and parts of South Asia in summer, and from the Middle East and Central Asia in winter. A footprint analysis indicates that a large fraction (>60%) of the black carbon contributions on Keqikaer Glacier comes from anthropogenic sources. These results provide a scientific basis for regional mitigation efforts to reduce black carbon.
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Constitutive models and salt migration mechanisms of saline frozen soil and the-state-of-the-practice countermeasures in cold regions
YuanMing Lai,ZheMin You,Jing Zhang
Sciences in Cold and Arid Regions    2021, 13 (1): 1-17.   DOI: 10.3724/SP.J.1226.2021.20045
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A series of saline soil-related problems, including salt expansion and collapse, frost heave and thaw settlement, threaten the safety of the road traffic and the built infrastructure in cold regions. This article presents a comprehensive review of the physical and mechanical properties, salt migration mechanisms of saline soil in cold environment, and the countermeasures in practice. It is organized as follows: (1) The basic physical characteristics; (2) The strength criteria and constitutive models; (3) Water and salt migration characteristics and mechanisms; and (4) Countermeasures of frost heave and salt expansion. The review provides a holistic perspective for recent progress in the strength characteristics, mechanisms of frost heave and salt expansion, engineering countermeasures of saline soil in cold regions. Future research is proposed on issues such as the effects of salt erosion on concrete and salt corrosion of metal under the joint action of evaporation and freeze-thaw cycles.

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Characteristics of permafrost degradation in Northeast China and its ecological effects: A review
ShanShan Chen,ShuYing Zang,Li Sun
Sciences in Cold and Arid Regions    2020, 12 (1): 1-11.   DOI: 10.3724/SP.J.1226.2020.00001.
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Latitudinal permafrost in Northern Northeast (NNE) China is located in the southern margin of the Eurasian continent, and is very sensitive to climatic and environmental change. Numerical simulations indicate that air temperature in the permafrost regions of Northeast China has been on the rise since the 1950s, and will keep rising in the 21st century, leading to extensive degradation of permafrost. Permafrost degradation in NNE China has its own characteristics, such as northward shifts in the shape of a "W" for the permafrost southern boundary (SLP), discontinuous permafrost degradation into island-like frozen soil, and gradually disappearing island permafrost. Permafrost degradation leads to deterioration of the ecological environment in cold regions. As a result, the belt of larch forests dominated by Larix gmelinii has shifted northwards and wetland areas with symbiotic relationships with permafrost have decreased significantly. With rapid retreat and thinning of permafrost and vegetation change, the CO2 and CH4 flux increases with mean air temperature from continuous to sporadic permafrost areas as a result of activity of methanogen enhancement, positively feeding back to climate warming. This paper reviews the features of permafrost degradation, the effects of permafrost degradation on wetland and forest ecosystem structure and function, and greenhouse gas emissions on latitudinal permafrost in NNE China. We also put forward critical questions about the aforementioned effects, including: (1) establish long-term permafrost observation systems to evaluate the distribution of permafrost and SLP change, in order to study the feedback of permafrost to climate change; (2) carry out research about the effects of permafrost degradation on the wetland ecosystem and the response of Xing'an larch to global change, and predict ecosystem dynamics in permafrost degradation based on long-term field observation; (3) focus intensively on the dynamics of greenhouse gas flux in permafrost degradation of Northeast China and the feedback of greenhouse gas emissions to climate change; (4) quantitative studies on the permafrost carbon feedback and vegetation carbon feedback due to permafrost change to climate multi-impact and estimate the balance of C in permafrost regions in the future.

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Cryosphere evapotranspiration in the Tibetan Plateau: A review
KunXin Wang,YinSheng Zhang,Ning Ma,YanHong Guo,YaoHui Qiang
Sciences in Cold and Arid Regions    2020, 12 (6): 355-370.   DOI: 10.3724/SP.J.1226.2020.00355
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Land surface actual evapotranspiration is an important process that influences the Earth's energy and water cycles and determines the water and heat transfer in the soil-vegetation-atmosphere system. Meanwhile, the cryosphere's hydrological process is receiving extensive attention, and its water problem needs to be understood from multiple perspectives. As the main part of the Chinese cryosphere, the Tibetan Plateau faces significant climate and environmental change. There are active interaction and pronounced feedback between the environment and ETa in the cryosphere. This article mainly focuses on the research progress of ETa in the Tibetan Plateau. It first reviews the ETa process, characteristics, and impact factors of typical underlying surfaces in the Tibetan Plateau (alpine meadows, alpine steppes, alpine wetlands, alpine forests, lakes). Then it compares the temporal and spatial variations of ETa at different scales. In addition, considering the current greening of cryosphere vegetation due to climate change, it discusses the relationship between vegetation greening and transpiration to help clarify how vegetation activities are related to the regional water cycle and surface energy budget.

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Frost susceptibility of soils―A confusing concept that can misguide geotechnical design in cold regions
DaiChao Sheng
Sciences in Cold and Arid Regions    2021, 13 (2): 87-94.   DOI: 10.3724/SP.J.1226.2021.20051
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Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments.

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Seasonal variation of airborne fungi of the Tiantishan Grottoes and Western Xia Museum, Wuwei, China
YuLong Duan,FaSi Wu,DongPeng He,RuiHong Xu,HuYuan Feng,Tuo Chen,GuangXiu Liu,WanFu Wang
Sciences in Cold and Arid Regions    2021, 13 (6): 522-532.   DOI: 10.3724/SP.J.1226.2021.20102
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In this study, a systematic survey of cultural airborne fungi was carried out in the occurrence environments of wall paintings that are preserved in the Tiantishan Grottoes and the Western Xia Museum, China. A bio-aerosol sampler was used for sampling in four seasons in 2016. Culture-dependent and -independent methods were taken to acquire airborne fungal concentration and purified strains; by the extraction of genomic DNA, amplification of fungal ITS rRNA gene region, sequencing, and phylogenetic analysis, thereafter the fungal community composition and distribution characteristics of different study sites were clarified. We disclosure the main environmental factors which may be responsible for dynamic changes of airborne fungi at the sampling sites. The concentration of cultural airborne fungi was in a range from 13 to 1,576 CFU/m3, no significant difference between the two sites at the Tiantishan Grottoes, with obvious characteristics of seasonal variation, in winter and spring were higher than in summer and autumn. Also, there was a significant difference in fungal concentration between the inside and outside of the Western Xia Museum, the outside of the museum was far more than the inside of the museum in the four seasons, particularly in the winter. Eight fungal genera were detected, including Cladosporium, Penicillium, Alternaria, and Filobasidium as the dominant groups. The airborne fungal community structures of the Tiantishan Grottoes show a distinct characteristic of seasonal variation and spatial distribution. Relative humidity, temperature and seasonal rainfall influence airborne fungal distribution. Some of the isolated strains have the potential to cause biodeterioration of ancient wall paintings. This study provides supporting information for the pre-warning conservation of cultural relics that are preserved at local sites and inside museums.

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Culturable bacterial diversity in hypolithic and peripheral soils in the west of the Hexi Corridor desert and its influencing factors
LiFang He,ShiWeng Li,GaoSen Zhang,XiuKun Wu,BingLin Zhang,Wei Zhang
Sciences in Cold and Arid Regions    2020, 12 (1): 47-58.   DOI: 10.3724/SP.J.1226.2020.00047.
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Microbes inhabiting the desert respond sensitively to environmental changes and may be an indicator for changes in the desert ecosystem. Hypolithic microbial communities in the desert play a vital role in ecosystem processes such as soil formation and organic matter accumulation. This study investigated and compared the culturable bacterial community structure and diversity in hypolithic and peripheral soils, and the interaction between bacteria and environmental factors. The bacteria were isolated using four different kinds of media and identified by 16S rRNA gene-sequence analysis. The numbers of culturable bacteria in the hypolithic and peripheral soils ranged from 3.0×104 to 3.6×105 CFU/g and from 6.5×104 to 5.3×105 CFU/g, respectively, indicating that the bacteria number in peripheral soil was higher than that in hypolithic soil. A total of 98 species belonging to 34 genera were identified, among which Arthrobacter, Bacillus,and Streptomyces were found dominantly and widely distributed. The community of culturable bacteria had obvious sample specificity, and the diversity in hypolithic soil was higher than that in peripheral soil. On the regional scale, the distribution of culturable bacteria and the environmental factors showed regular changes. On the local scale, the high heterogeneity of the hypolithic environment determined the specificity of the number and species of culturable bacteria.

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Study of thermal properties of supraglacial debris and degree-day factors on Lirung Glacier, Nepal
Mohan Bahadur Chand,Rijan Bhakta Kayastha
Sciences in Cold and Arid Regions    2018, 10 (5): 357-368.   DOI: 10.3724/SP.J.1226.2018.00357
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The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons. Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon (2013), winter (2013), and pre-monsoon (2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors (DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of ?20.81 °C/m, 4.05 °C/m, and ?7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.

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Fossil Taiwannia from the Lower Cretaceous Yixian Formation of western Liaoning, Northeast China and its phytogeography significance
MingZhen Zhang,BaoXia Du,PeiHong Jin,BaiNian Sun
Sciences in Cold and Arid Regions    2018, 10 (6): 502-515.   DOI: 10.3724/SP.J.1226.2018.00502
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Fossil Taiwania was discovered from the Lower Cretaceous Yixian Formation of Lingyuan City, western Liaoning Province, Northeast China. It is identified as a new species, Taiwania lingyuanensis sp. nov.. The present specimen is preserved as impressions with well defined leaf shoots system and reproductive structures. Leaves are dimorphic, spirally and imbricately arranged. They are scale-like on the main and cone-bearing branchlets, and subulate to falcate-subulate on the juvenile or sterile shoots. The seed cones are singly elliptic, ovate or elongate-ovate and terminally borne on ultimate shoots, bearing 22–24 scale-bracts complexes imbricately and helically arranged around the cone axis, the bracts are broad-ovate, rhomboidal or hexagonal with entire margins. Both the leafy shoots morphology and reproductive structures are similar to extant Taiwania. Furthermore, geological distribution and molecular biological evidences support that Taiwania is probably originated from the eastern Asia at least in the Early Cretaceous and widely distributed in the North Hemisphere thereafter.

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Guest Editors Fujun Niu and Jiankun Liu for special Issue International Conference on Permafrost
Sciences in Cold and Arid Regions    2021, 13 (2): 1-1.  
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Biological improvement of saline alkali soil reference system: A review
XueQin Wang,Xu Xing,FengJu Zhang,Kong Xin
Sciences in Cold and Arid Regions    2018, 10 (6): 516-521.   DOI: 10.3724/SP.J.1226.2018.00000
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This work presents a reference system overview to improve the efficiency of biological improvement of saline-alkali soil developed during the last thirty years, ranging from connotation, general methods and species, soil desalination, soil structure, soil organic content, microbial flora, enzyme activity, yield and economic benefits. The reference system presented is divided into three main groups: suitable varieties, suitable cultivation measures, and a comprehensive evaluation system. There has been a lot of research on biological improvement of saline alkali soil, but these studies are very fragmented and lack a comprehensive standard system. Also, there is a lack of practical significance, particularly with regard to optimal species, densities and times of sowing for particular regions. On the other hand, the corresponding cultivation measure is very important. Therefore, a reference system plays an important role to the effect of biological improvement of saline alkali soil.

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Numerical simulations on cutting of frozen soil using HJC Model
WenQiang Zhang,YongHong Niu
Sciences in Cold and Arid Regions    2020, 12 (3): 134-143.   DOI: 10.3724/SP.J.1226.2020.00134
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Numerical simulation is known as an effective method for mechanical properties during frozen soil excavation. In order to reveal the development of cutting force, effective stress and cutting fragments in frozen silt during the cutting process, we introduce an explicit finite element program LS-DYNA to establish a two-dimensional numerical model of the frozen soil cut. We also use the Holmquist-Johnson-Cook (HJC) damage constitutive model for simulating the variation of soil mechanical properties according to the strong dependence between the cutting tool and frozen silt during the process with different cutting depths, angles and velocities. Meanwhile, a series of experimental results are acquired of frozen silt cutting to prove the application of the HJC model during simulation of cutting force variations. The result shows that the cutting force and fragment size are strongly influenced by cutting depths and cutting velocities increased, and the maximum effective stress at points where the tool contacts frozen soil during the cutting process. In addition, when the cutting angle is 52°, the cutting force is the smallest, and the cutting angle is optimum. Thus, the prediction of frozen soil mechanical properties on the cutting process by this model is conducive to selecting machinery equipment in the field.

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Biodiversity, productivity, and temporal stability in a natural grassland ecosystem of China
Bing Liu, WenZhi Zhao, YangYang Meng, Chan Liu
Sciences in Cold and Arid Regions    2018, 10 (4): 293-304.   DOI: 10.3724/SP.J.1226.2018.00293
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Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richness and aboveground biomass, and simulated the competitive assemblages in a natural grassland ecosystem of China, aiming to test some assumptions and predictions about biodiversity–stability relationships. Our results show that aboveground productivity and temporal stability increased significantly with increasing species richness, and via a combination of overyielding, species asynchrony, and portfolio effects. Species interactions resulted in overyielding caused by trait-independent complementarity, and were not offset by a negative dominance effect and trait-dependent complementarity effect. Therefore, the mechanisms underlying the biodiversity effect shifted from the selection effect to the complementarity effect as diversity increased, and both effects were coexisted but the complementarity effect represent a mechanism that facilitates long term species coexistence in a natural grassland ecosystem of China.

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Summary of research on frost heave for subgrade in seasonal frozen ground
Shuang Jia,BoWen Tai,ShouChen Qi,Lei Li,Tao Chen
Sciences in Cold and Arid Regions    2021, 13 (3): 195-205.   DOI: 10.3724/SP.J.1226.2021.20092.
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The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens' living standards. However, railway construction in seasonally frozen soil areas is often faced with frost heave, leading to uneven subgrades which seriously threaten traffic safety. This article summarizes extant research results on frost heave mechanism, frost heave factors, and anti-frost measures of railway subgrades in seasonally frozen soil areas.

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A meta-analysis of the impacts of forest logging on soil CO2 efflux
LongFei Chen,YangZhou Xiang,ZhiBin He,Jun Du,PengFei Lin,Xi Zhu
Sciences in Cold and Arid Regions    2020, 12 (3): 165-179.   DOI: 10.3724/SP.J.1226.2020.00165
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Soil CO2 efflux, the second largest flux in a forest carbon budget, plays an important role in global carbon cycling. Forest logging is expected to have large effects on soil CO2 efflux and carbon sequestration in forest ecosystems. However, a comprehensive understanding of soil CO2 efflux dynamics in response to forest logging remains elusive due to large variability in results obtained across individual studies. Here, we used a meta-analysis approach to synthesize the results of 77 individual field studies to determine the impacts of forest logging on soil CO2 efflux. Our results reveal that forest logging significantly stimulated soil CO2 efflux of the growing season by 5.02%. However, averaged across all studies, non-significant effect was detected following forest logging. The large variation among forest logging impacts was best explained by forest type, logging type, and time since logging. Soil CO2 efflux in coniferous forests exhibited a significant increase (4.38%) due to forest logging, while mixed and hardwood forests showed no significant change. Logging type also had a significant effect on soil CO2 efflux, with thinning increasing soil CO2 efflux by 12.05%, while clear-cutting decreasing soil CO2 efflux by 8.63%. The time since logging also had variable effects, with higher soil CO2 efflux for 2 years after logging, and lower for 3-6 years after logging; when exceeded 6 years, soil CO2 efflux increased. As significantly negative impacts of forest logging were detected on fine root biomass, the general positive effects on soil CO2 efflux can be explained by the accelerated decomposition of organic matter as a result of elevated soil temperature and organic substrate quality. Our results demonstrate that forest logging had potentially negative effects on carbon sequestration in forest ecosystems.

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Theoretical expressions for soil particle detachment rate due to saltation bombardment in wind erosion
XuYang Liu,WenXiao Ning,ZhenTing Wang
Sciences in Cold and Arid Regions    2020, 12 (4): 234-241.   DOI: 10.3724/SP.J.1226.2020.00234
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Saltation bombardment is a dominate dust emission mechanism in wind erosion. For loose surfaces, splash entrainment has been well understood theoretically. However, the mass loss predictions of cohesive soils are generally empirical in most wind erosion models. In this study, the soil particle detachment of a bare, smooth, dry, and uncrusted soil surface caused by saltation bombardment is modeled by means of classical mechanics. It is shown that detachment rate can be analytically expressed in terms of the kinetic energy or mass flux of saltating grains and several common mechanical parameters of soils, including Poisson's ratio, Young's modulus, cohesion and friction angle. The novel expressions can describe dust emission rate from cohesive surfaces and are helpful to quantify the anti-erodibility of soil. It is proposed that the mechanical properties of soils should be appropriately included in physically-based wind erosion models.

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Seed germination and seedling growth of Pycnanthus angolensis (Welw.) Warb., African false nutmeg
Sakpere A.M.A.
Sciences in Cold and Arid Regions    2019, 11 (5): 350-359.   DOI: 10.3724/SP.J.1226.2019.00350.
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This study investigated the germination behavior and seedling growth of Pycnanthus angolensis seeds. The germination study was carried out in the laboratory and included pretreatment studies and observation of the seed-germination process. For each treatment, three replications of 20 seeds were sown in a transparent plastic germination box (12cm × 22cm × 5cm) lined with moistened filter paper at room temperature. To monitor seedling growth, seedlings were transplanted into pots filled with topsoil and laid out in a completely randomized design. Ten seedlings replicated thrice were measured monthly; and the shoot height, leaf area, and root length, as well as the fresh and dry weights of the seedlings, were recorded. Results showed that mechanically scarified seeds exhibited the significantly highest germination percent (83.33%, P <0.005), followed by control seeds (70.83%), whereas seeds treated with 98% sulphuric acid (H2SO4) displayed the lowest germination percent (1.67). The endospermous seeds exhibited cryptogeal germination, while seeds stored for a month (with or without arils) failed to germinate. During seed germination, radicle protrusion continued with a pseudo-opening of the root, through which the brownish cotyledonary petiole was emitted, thus releasing the plumule at the posterior position. Moreover, P. angolensis exhibited a slow growth rate, attaining a shoot height of 73 cm within a year. The highest positive change in leaf number and area was recorded in the fourth month, a period during which the least change in shoot height occurred. The study concluded that mechanical scarification of the seeds ensured significant and faster germination than chemical scarification or no treatment at all. Additionally, P. angolensis displayed a cryptogeal germination, with the seedling growth of the tree species observed to be slow.

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Progress, problems and prospects of palynology in reconstructing environmental change in inland arid areas of Asia
YongTao Zhao,YunFa Miao,Yan Lei,XianYong Cao,MingXing Xiang
Sciences in Cold and Arid Regions    2021, 13 (4): 271-291.   DOI: 10.3724/SP.J.1226.2021.20049.
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Studying the climatic and environmental changes on different time scales in inland arid regions of Asia can greatly improve our understanding of climatic influences for the Qinghai-Tibet Plateau in the context of global change. Pollen, as a remnant of seed plants, is sensitive to environmental factors including precipitation, temperature and altitude, and is a classic proxy in environmental reconstruction. In the last two decades, great progress in the application of palynology to inland areas of Asia has highlighted the role of palynology in paleoclimatic and paleoenvironmental research. The main progress is as follows. (1) On the tectonic time scale of the late Cenozoic, the palaeoclimatological sequence has been established on the basis of pollen percentage, concentration and taxon. Pollen data have revealed a continuous enhancement of drought in the inland arid region of Asia, in contrast to evidence acquired based on other proxies. (2) In the late Quaternary, an increase in herbaceous plants further supports the intensification of drought associated with global cooling. In more detail, the palynological record shows a glacial-interglacial pattern consistent with changes in global ice volume. (3) The Holocene pollen record has been established at a high resolution and across a wide range of inland areas. In general, it presents an arid grassland environment in the early Holocene, followed by the development of woody plants in the mid- to late-Holocene climate optimum. This pattern is related to moisture changes in areas dominated by the westerlies. There are also significant regional differences in the pattern and amplitude of vegetation response to the Holocene environment. (4) Modern pollen studies based on vegetation surveys, meteorological data and statistics show that topsoil palynology can better reflect regional vegetation types (e.g., grassland, meadow, desert). Drier climates yield higher pollen contents of drought-tolerant plants such as Chenopodioideae, Ephedra, and Nitriaria, while contents of Artemisia and Poaceae are greater under humid climates. Besides these achievements, problems remain in palynological research: for example, pollen extraction, identification, interpretation, and quantitative reconstruction. In the future, we encourage strengthened interdisciplinary cooperation to improve experimental methods and innovation. Firstly, we should strengthen palynological classification and improve the skill of identification; secondly, laboratory experiments are needed to better constrain pollen transport dynamics in water and air; thirdly, more rigorous mathematical principles will improve the reliability of reconstructions and deepen the knowledge of plant geography; and finally, new areas and methods in palynology should be explored, for example DNA, UV-B and isotopic analysis. It is expected that palynology will continue to develop, and we hope it will continue to play an important role in the study of past climatic and environmental changes.

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Changes in the global cryosphere and their impacts: A review and new perspective
ShiYin Liu,TongHua Wu,Xin Wang,XiaoDong Wu,XiaoJun Yao,Qiao Liu,Yong Zhang,JunFeng Wei,XiaoFan Zhu
Sciences in Cold and Arid Regions    2020, 12 (6): 343-354.   DOI: 10.3724/SP.J.1226.2020.00343
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As one of the five components of Earth's climatic system, the cryosphere has been undergoing rapid shrinking due to global warming. Studies on the formation, evolution, distribution and dynamics of cryospheric components and their interactions with the human system are of increasing importance to society. In recent decades, the mass loss of glaciers, including the Greenland and Antarctic ice sheets, has accelerated. The extent of sea ice and snow cover has been shrinking, and permafrost has been degrading. The main sustainable development goals in cryospheric regions have been impacted. The shrinking of the cryosphere results in sea-level rise, which is currently affecting, or is soon expected to affect, 17 coastal megacities and some small island countries. In East Asia, South Asia and North America, climate anomalies are closely related to the extent of Arctic sea ice and snow cover in the Northern Hemisphere. Increasing freshwater melting from the ice sheets and sea ice may be one reason for the slowdown in Atlantic meridional overturning circulation in the Arctic and Southern Oceans. The foundations of ports and infrastructure in the circum-Arctic permafrost regions suffer from the consequences of permafrost degradation. In high plateaus and mountainous regions, the cryosphere's shrinking has led to fluctuations in river runoff, caused water shortages and increased flooding risks in certain areas. These changes in cryospheric components have shown significant heterogeneity at different temporal and spatial scales. Our results suggest that the quantitative evaluation of future changes in the cryosphere still needs to be improved by enhancing existing observations and model simulations. Theoretical and methodological innovations are required to strengthen social economies' resilience to the impact of cryospheric change.

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Spatial distribution of supraglacial debris thickness on glaciers of the China-Pakistan Economic Corridor and surroundings
YaJie Zheng,Yong Zhang,Ju Gu,Xin Wang,ZongLi Jiang,JunFeng Wei
Sciences in Cold and Arid Regions    2020, 12 (6): 447-460.   DOI: 10.3724/SP.J.1226.2020.00447
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Debris-covered glaciers, characterized by the presence of supraglacial debris mantles in their ablation zones, are widespread in the China-Pakistan Economic Corridor (CPEC) and surroundings. For these glaciers, thin debris layers accelerate the melting of underlying ice compared to that of bare ice, while thick debris layers retard ice melting, called debris-cover effect. Knowledge about the thickness and thermal properties of debris cover on CPEC glaciers is still unclear, making it difficult to assess the regional debris-cover effect. In this study, thermal resistance of the debris layer estimated from remotely sensed data reveals that about 54.0% of CPEC glaciers are debris-covered glaciers, on which the total debris-covered area is about 5,072 km2, accounting for 14.0% of the total glacier area of the study region. We find that marked difference in the extent and thickness of debris cover is apparent from region to region, as well as the debris-cover effect. 53.3% of the total debris-covered area of the study region is concentrated in Karakoram, followed by Pamir with 30.2% of the total debris-covered area. As revealed by the thermal resistance, the debris thickness is thick in Hindu Kush on average, with the mean thermal resistance of 7.0×10-2 ((m2?K)/W), followed by Karakoram, while the thickness in western Himalaya is thin with the mean value of 2.0×10-2 ((m2?K)/W). Our findings provide a basis for better assessments of changes in debris-covered glaciers and their associated hydrological impacts in the CPEC and surroundings.

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Influence of fines content on the anti-frost properties of coarse-grained soil
TianLiang Wang, ZuRun Yue, TieCheng Sun, JinChuang Hua
Sciences in Cold and Arid Regions    2015, 7 (4): 407-413.   DOI: 10.3724/SP.J.1226.2015.00407
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This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows:(1) the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; (2) the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; (3) with increasing numbers of freeze-thaw cycles,the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engineering design values; and (4) considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway subgrade coarse-grained soil fillings in frozen regions.
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Spatiotemporal change of carbon storage in the Loess Plateau of northern Shaanxi, based on the InVEST Model
ShaoYang Liu, NingKe Hu, Jin Zhang, ZhiChao Lv
Sciences in Cold and Arid Regions    2018, 10 (3): 240-250.   DOI: 10.3724/SP.J.1226.2018.00240
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In recent years, land use and land cover have under gone tremendous change on the Loess Plateau, leading to temporal and spatial variation over many ecological factors, such as carbon storage. Based on four series of land-use data from remote-sensing imaging, spatiotemporal changes of land-use types and volume changes were analyzed. Combined with carbon-stock-assessment modules of the InVEST (integrated valuation ecosystem services and tradeoffs) model, the carbon-storage change was estimated and analyzed at the subcounty and subbasin scales. The results show that (1) cultivated land and grassland area decreased, while woodland and urban land area increased in northern Shaanxi; (2) the average carbon storage in Huangling County and the Beiluo River Basin is the largest, while that of Yuyang County and the Xinshui River Basin is the minimum, and that of Wuqi County showed the greatest growth; (3) carbon storage in the study area showed a definite decrease in 2000, but in general has increased from 1995 to 2010; (4) carbon-storage figures of subbasins and counties are all restricted by the natural status and land-use landscape of the whole study area. From the results, it can be seen that the effect of ecological policies is remarkable. This study has important implications for the rational planning of land use, adjustment of the ecosystem carbon cycle, and related policies.
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Surface-deformation monitoring in the permafrost regions over the Tibetan Plateau, using Sentinel-1 data
ZhenMing Wu, Lin Zhao, Lin Liu, Rui Zhu, ZeShen Gao, YongPing Qiao, LiMing Tian, HuaYun Zhou, MeiZhen Xie
Sciences in Cold and Arid Regions    2018, 10 (2): 114-125.   DOI: 10.3724/SP.J.1226.2018.00114
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Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to measure surface deformation over the Tibetan Plateau. However, the accuracy and applicability of the D-InSAR method are not well estimated due to the lack of in-situ validation. In this paper, we mapped the seasonal and long-term displacement of Tanggula (TGL) and Liangdaohe (LDH) permafrost regions with a stack of Sentinel-1 acquisitions using the Small Baseline Subset InSAR (SBAS-InSAR) method. In the TGL region, with its dry soils and sparse vegetation, the InSAR-derived surface-deformation trend was consistent with ground-based leveling results; long-term changes of the active layer showed a settlement rate of around 1 to 3 mm/a due to the melting of ground ice, indicating a degrading permafrost in this area. Around half of the deformation was picked up on monitoring, in contrast with in-situ measurements in LDH, implying that the D-InSAR method remarkably underestimated the surface-deformation. This phenomenon may be induced by the large soil-water content, high vegetation coverage, or a combination of these two factors in this region. This study demonstrates that surface deformation could be mapped accurately for a specific region with Sentinel-1 C-band data, such as in the TGL region. Moreover, although the D-InSAR technology provides an efficient solution for broad surface-deformation monitoring in permafrost regions, it shows a poor performance in the region with high soil-water content and dense vegetation coverage.
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Thickness estimation of the Longbasaba Glacier: methods and application
GuangLi He,JunFeng Wei,Xin Wang
Sciences in Cold and Arid Regions    2020, 12 (6): 477-490.   DOI: 10.3724/SP.J.1226.2020.00477
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A total of 71,177 glaciers exist on the Qinghai-Tibet Plateau, according to the Randolph Glacier Inventory (RGI 6.0). Despite their large number, glacier ice thickness data are relatively scarce. This study utilizes digital elevation model data and ground-penetrating radar thickness measurements to estimate the distribution and variation of ice thickness of the Longbasaba Glacier using Glacier bed Topography (GlabTop), a full-width expansion model, and the Huss and Farinotti (HF) model. Results show that the average absolute deviations of GlabTop, the full-width expansion model, and the HF model are 9.8, 15.5, and 10.9 m, respectively, indicating that GlabTop performs the best in simulating glacier thickness distribution. During 1980-2015, the Longbasaba Glacier thinned by an average of 7.9±1.3 m or 0.23±0.04 m/a, and its ice volume shrunk by 0.28±0.04 km3 with an average reduction rate of 0.0081±0.0001 km3/a. In the investigation period, the area and volume of Longbasaba Lake expanded at rates of 0.12±0.01 km2/a and 0.0132±0.0018 km3/a, respectively. This proglacial lake could potentially extend up to 5,000 m from the lake dam.

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A review of the interaction between the cryosphere and atmosphere
YongJian Ding,JianPing Yang,ShengXia Wang,YaPing Chang
Sciences in Cold and Arid Regions    2020, 12 (6): 329-342.   DOI: 10.3724/SP.J.1226.2020.00329
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The interaction between the cryosphere and atmosphere is an essential and extremely sensitive mutual action process on the earth. Due to global warming and the cryospheric melting, more and more attention has been paid to the interaction process between the cryosphere and atmosphere, especially the feedback of the cryosphere change to the atmosphere. A comprehensive review of the studies on the interaction between the cryosphere and atmosphere is conducted from two aspects: (1) effects of climate change on the cryosphere or responses of the cryosphere to climate change; and (2) feedback of the cryosphere change to the climate. The response of the cryosphere to climate change is lagging. Such a lagging and cumulative effect of temperature rise within the cryosphere have resulted in a rapid change in the cryosphere in the 21st century, and its impacts have become more significant. The feedback from cryosphere change on the climate are omnifarious. Among them, the effects of sea ice loss and snow cover change, especially the Arctic sea ice loss and the Northern Hemisphere snow cover change, are the most prominent. The Arctic amplification (AA) associated with sea ice feedback is disturbing , and the feedback generated by the effect of temperature rise on snow properties in the Northern Hemisphere is also of great concern. There are growing evidence of the impact of the Arctic cryosphere melting on mid-latitude weather and climate. Weakened storm troughs, steered jet stream and amplified planetary waves associated with energy propagation become the key to explaining the links between Arctic cryosphere change and atmospheric circulation. There is still a great deal of uncertainty about how cryosphere change affects the weather and climate through different atmospheric circulation processes at different spatial and temporal scales due to observation and simulation problems.

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Cutting of Phragmites australis as a lake restoration technique: Productivity calculation and nutrient removal in Wuliangsuhai Lake, northern China
Jan Felix Köbbing, Niels Thevs, Stefan Zerbe
Sciences in Cold and Arid Regions    2016, 8 (5): 400-410.   DOI: 10.3724/SP.J.1226.2016.00400
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Reed is one of the most frequent and dominant species in wetlands all over the world, with common reed (Phragmites australis (Cav.) Trin. ex Steud.) as the most widely distributed species. In many wetlands, P. australis plays a highly ambivalent role. On the one hand, in many wetlands it purifies wastewater, provides habitat for numerous species, and is a potentially valuable raw material, while on the other hand it is an invasive species which expands aggressively, prevents fishing, blocks ditches and waterways, and builds monospecies stands. This paper uses the eutrophic reed-swamp of Wuliangsuhai Lake in Inner Mongolia, northern China, as a case to present the multiple benefits of regular reed cutting. The reed area and aboveground biomass production are calculated based on field data. Combined with data about water and reed nutrient content, the impact of reed cutting on the lake nutrient budget (N and P) is investigated. Currently, at this lake around 100,000 tons of reed are harvested in winter annually, removing 16% and 8% of the total nitrogen and phosphorus influx, respectively. Harvesting all available winter reed could increase the nutrient removal rates to 48% and 24%, respectively. We also consider the effects of summer harvesting, in which reed biomass removal could overcompensate for the nutrient influx but could potentially reduce reed regrowth.
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Comparative study of probable maximum precipitation and isohyetal maps for mountainous regions, Pakistan
Muhammad Waseem Boota, Ghulam Nabi, Tanveer Abbas, HuiJun Jin, Ayesha Yousaf, Muhammad Azeem Boota
Sciences in Cold and Arid Regions    2018, 10 (1): 55-68.   DOI: 10.3724/SP.J.1226.2018.00055
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Probable maximum precipitation (PMP) is widely used by hydrologists for appraisal of probable maximum flood (PMF) used for soil and water conservation structures, and design of dam spillways. A number of methods such as empirical, statistical and dynamic are used to estimate PMP, the most favored being statistical and hydro-meteorological. In this paper, PMP estimation in mountainous regions of Pakistan is studied using statistical as well as physically based hydro-meteorological approaches. Daily precipitation, dew point, wind speed and temperature data is processed to estimate PMP for a one-day duration. Maximum precipitation for different return periods is estimated by using statistical approaches such as Gumble and Log-Pearson type-III (LP-III) distribution. Goodness of fit (GOF) test, chi-square test, correlation coefficient and coefficient of determination were applied to Gumble and LP-III distributions. Results reveal that among statistical approaches, Gumble distribution performed the best result compared to LP-III distribution. Isohyetal maps of the study area at different return periods are produced by using the GIS tool, and PMP in mountainous regions varies from 150 to 320 mm at an average value of 230.83 mm. The ratio of PMP for one-day duration to highest observed rainfall (HOR) varied from 1.08 to 1.29 with an average value of 1.18. An appropriate frequency factor (Km) is very important which is a function of mean for observed precipitation and PMP for 1-day duration, and Km values varies from 2.54 to 4.68. The coefficient of variability (Cv) varies from minimum value of 28% to maximum value of 43.35%. It was concluded that the statistical approach gives higher results compared to moisture maximization (MM) approach. In the hydro-meteorological approach, moisture maximization (MM) and wind moisture maximization (WMM) techniques were applied and it was concluded that wind moisture maximization approach gives higher results of PMP as compared to moisture maximization approach as well as for Hershfield technique. Therefore, it is suggested that MM approach is the most favored in the study area for PMP estimation, which leads to acceptable results, compared to WMM and statistical approaches.
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Characteristics of land-atmosphere energy and turbulent fluxes over the plateau steppe in central Tibetan Plateau
MaoShan Li, ZhongBo Su, YaoMing Ma, XueLong Chen, Lang Zhang, ZeYong Hu
Sciences in Cold and Arid Regions    2016, 8 (2): 103-115.   DOI: 10.3724/SP.J.1226.2016.00103
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The land-atmosphere energy and turbulence exchange is key to understanding land surface processes on the Tibetan Plateau(TP).Using observed data for Aug.4 to Dec.3,2012 from the Bujiao observation point(BJ) of the Nagqu Plateau Climate and Environment Station(NPCE-BJ),different characteristics of the energy flux during the Asian summer monsoon(ASM) season and post-monsoon period were analyzed.This study outlines the impact of the ASM on energy fluxes in the central TP.It also demonstrates that the surface energy closure rate during the ASM season is higher than that of the post-monsoon period.Footprint modeling shows the distribution of data quality assessments(QA) and quality controls(QC) surrounding the observation point.The measured turbulent flux data at the NPCE-BJ site were highly representative of the target land-use type.The target surface contributed more to the fluxes under unstable conditions than under stable conditions.The main wind directions(180°and 210°) with the highest data density showed flux contributions reaching 100%,even under stable conditions.The lowest flux contributions were found in sectors with low data density, e.g.,90.4% in the 360°sector under stable conditions during the ASM season.Lastly,a surface energy water balance(SEWAB) model was used to gap-fill any absent or corrected turbulence data.The potential simulation error was also explored in this study.The Nash-Sutcliffe model efficiency coefficients(NSEs) of the observed fluxes with the SEWAB model runs were 0.78 for sensible heat flux and 0.63 for latent heat flux during the ASM season,but unrealistic values of-0.9 for latent heat flux during the post-monsoon period.
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Simulation and prediction of monthly accumulated runoff, based on several neural network models under poor data availability
JianPing Qian,JianPing Zhao,Yi Liu,XinLong Feng,DongWei Gui
Sciences in Cold and Arid Regions    2018, 10 (6): 468-481.   DOI: 10.3724/SP.J.1226.2018.00468
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Most previous research on areas with abundant rainfall shows that simulations using rainfall-runoff modes have a very high prediction accuracy and applicability when using a back-propagation (BP), feed-forward, multilayer perceptron artificial neural network (ANN). However, in runoff areas with relatively low rainfall or a dry climate, more studies are needed. In these areas—of which oasis-plain areas are a particularly good example—the existence and development of runoff depends largely on that which is generated from alpine regions. Quantitative analysis of the uncertainty of runoff simulation under climate change is the key to improving the utilization and management of water resources in arid areas. Therefore, in this context, three kinds of BP feed-forward, three-layer ANNs with similar structure were chosen as models in this paper. Taking the oasis–plain region traverse by the Qira River Basin in Xinjiang, China, as the research area, the monthly accumulated runoff of the Qira River in the next month was simulated and predicted. The results showed that the training precision of a compact wavelet neural network is low; but from the forecasting results, it could be concluded that the training algorithm can better reflect the whole law of samples. The traditional artificial neural network (TANN) model and radial basis-function neural network (RBFNN) model showed higher accuracy in the training and prediction stage. However, the TANN model, more sensitive to the selection of input variables, requires a large number of numerical simulations to determine the appropriate input variables and the number of hidden-layer neurons. Hence, The RBFNN model is more suitable for the study of such problems. And it can be extended to other similar research arid-oasis areas on the southern edge of the Kunlun Mountains and provides a reference for sustainable water-resource management of arid-oasis areas.

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A review on the ambit and prospects of C3 and C4 plants in Nigeria
Abdulwakeel Ayokun-nun Ajao, Oludare Oladipo Agboola, Sefiu Adekilekun Saheed
Sciences in Cold and Arid Regions    2017, 9 (6): 587-598.   DOI: 10.3724/SP.J.1226.2017.00587
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Despite the enormous applications of photosynthesis in global carbon budget and food security, photosynthesis research has not been adequately explored as a research focus in Nigeria. Previous works on C3 and C4 plants in Nigeria were mainly on the use of anatomical characteristics to delimit plant species into their respective pathways, with no attention being paid to its applications. In this review, past and present knowledge gaps in this area of study are elucidated. Information used in this review were sourced from referred research articles and books in reputable journals. The results revealed that C3 and C4 plants are distributed among 21 genera and 11 families in Nigeria. In addition there is dearth of informatio such that only three genera have been classified based on diverse photosynthetic pathways with no information found on the physiological and biochemical characterization of these genera. Moreover, further research is also suggested for tackling new challenges in the area of food productivity and climate change.
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Cracking in an expansive soil under freeze–thaw cycles
Yang Lu, SiHong Liu
Sciences in Cold and Arid Regions    2017, 9 (4): 392-397.   DOI: 10.3724/SP.J.1226.2017.00392
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Expansive soils located in cold regions can easily endure the action of frost heaving and cyclic freezing–thawing. Cracking can also occur in expansive clayey soils under freeze–thaw cycles, of which little attention has been paid on this issue. In this study, laboratory experiment and cracking analysis were performed on an expansive soil. Crack patterns were quantitatively analyzed using the fractal concept. The relationships among crack pattern, water loss, number of freeze–thaw cycles, and fractal dimension were discussed. It was found that crack patterns on the surface exhibit a hierarchical network structure that is fractal at a statistical level. Cracks induced by freeze–thaw cycles are shorter, more irregularly oriented, and slowly evolves from an irregularly rectilinear pattern towards a polygonal or quasi–hexagonal one; water loss, closely related to specimen thickness, plays a significant role in the process of soil cracking; crack development under freeze-thaw cycles are not only attributed to capillary effect, but also to expansion and absorption effects.
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Proline and soluble sugars accumulation in three pepper species (Capsicum spp) in response to water stress imposed at different stages of growth
Gideon O. Okunlola, Richard O. Akinwale, Adekunle A. Adelusi
Sciences in Cold and Arid Regions    2016, 8 (3): 205-211.   DOI: 10.3724/SP.J.1226.2016.00205
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Drought is a major production constraint for major fruits and vegetable crops in the tropics.This study was conducted to investigate the effect of limited water supply at three growth stages (vegetative,flowering and fruiting) on the accumulation of proline and soluble sugars in three pepper species.Seeds of the three pepper species,Capsicum chinense Jacq.,C.annuum L.and C.frutescens L.were raised in a nursery and the seedlings were transplanted into seventy two plastic pots arranged in a randomized complete block design with three replicates,25 days after planting.Four water treatments,200 mL of water supplied twice daily (W1),once in every three days (W2),once in every five days (W3),and zero water supplied throughout growing period (W0) were imposed at three vegetative,flowering,and fruiting growth stages.Data were collected on relative water content,free proline and total soluble sugar.Data collected were subjected to analysis of variance and means were separated using Duncan's multiple range test.Results show that the concentration of proline and soluble sugar in leaves of the three pepper species were found to be remarkable at the different stages of growth in the stressed plants.
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The mass-balance characteristics and sensitivities to climate variables of Laohugou Glacier No. 12, western Qilian Mountains, China
JiZu Chen, ShiChang Kang, Xiang Qin, WenTao Du, WeiJun Sun, YuShuo Liu
Sciences in Cold and Arid Regions    2017, 9 (6): 543-553.   DOI: 10.3724/SP.J.1226.2017.00543
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Due to global warming, glaciers on the Tibetan Plateau (TP) are experiencing widespread shrinkage; however, the mechanisms controlling glacier variations across the TP are still rather unclear, especially on the northeastern TP. In this study, a physically based, distributed surface-energy and mass-balance model was used to simulate glacier mass balance forced by meteorological data. The model was applied to Laohugou No. 12 Glacier, western Qilian Mountains, China, during 2010~2012. The simulated albedo and mass balance were validated and calibrated by in situ measurements. The simulated annual glacier-wide mass balances were -385 mm water equivalent (w.e.) in 2010/2011 and -232 mm w.e. in 2011/2012, respectively. The mean equilibrium-line altitude (ELA) was 5,015 m a.s.l., during 2010~2012, which ascended by 215 m compared to that in the 1970s. The mean accumulation area ratio (AAR) was 39% during the two years. Climatic-sensitivity experiments indicated that the change of glacier mass balance resulting from a 1.5 ℃ increase in air temperature could be offset by a 30% increase in annual precipitation. The glacier mass balance varied linearly with precipitation, at a rate of 130 mm w.e. per 10% change in total precipitation.
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Uncertainty analysis of runoff and sedimentation in a forested watershed using sequential uncertainty fitting method
Tanveer Abbas, Ghulam Nabi, Muhammad W. Boota, Fiaz Hussain, Muhammad I. Azam, HuiJun Jin, Muhammad Faisal
Sciences in Cold and Arid Regions    2016, 8 (4): 297-310.   DOI: 10.3724/SP.J.1226.2016.00297
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The Soil and Water Assessment Tool (SWAT) was implemented in a small forested watershed of the Soan River Basin in northern Pakistan through application of the sequential uncertainty fitting (SUFI-2) method to investigate the associated uncertainty in runoff and sediment load estimation. The model was calibrated for a 10-year period (1991-2000) with an initial 4-year warm-up period (1987-1990), and was validated for the subsequent 10-year period (2001-2010). The model evaluation indices R2 (the coefficient of determination), NS (the Nash-Sutcliffe efficiency), and PBIAS (percent bias) for stream flows simulation indicated that there was a good agreement between the measured and simulated flows. To assess the uncertainty in the model outputs, p-factor (a 95% prediction uncertainty, 95PPU) and r-factors (average wideness width of the 95PPU band divided by the standard deviation of the observed values) were taken into account. The 95PPU band bracketed 72% of the observed data during the calibration and 67% during the validation. The r-factor was 0.81 during the calibration and 0.68 during the validation. For monthly sediment yield, the model evaluation coefficients (R2 and NS) for the calibration were computed as 0.81 and 0.79, respectively; for validation, they were 0.78 and 0.74, respectively. Meanwhile, the 95PPU covered more than 60% of the observed sediment data during calibration and validation. Moreover, improved model prediction and parameter estimation were observed with the increased number of iterations. However, the model performance became worse after the fourth iterations due to an unreasonable parameter estimation. Overall results indicated the applicability of the SWAT model with moderate levels of uncertainty during the calibration and high levels during the validation. Thus, this calibrated SWAT model can be used for assessment of water balance components, climate change studies, and land use management practices.
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Research on pile performance and state-of-the-art practice in cold regions
JianKun Liu, TengFei Wang, Zhi Wen
Sciences in Cold and Arid Regions    2018, 10 (1): 1-11.   DOI: 10.3724/SP.J.1226.2018.00001
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A pile foundation is commonly adopted in geotechnical engineering to support structures, and its application has been extended to cold-regions engineering. In past decades, a host of scholars investigated pile behaviors and proposed design guidelines for seasonally frozen ground or permafrost. This paper reviews the research with respect to pile performance and engineering practice in cold regions, organized as follows: (1) creep tests and bearing capacity, (2) frost-jacking hazards, (3) laterally loaded piles, (4) dynamic responses, (5) refreezing due to concrete-hydration heat, and (6) improved countermeasures and design methods. We first summarize previous research and recent progress; then, predict the development trend of pile foundations in cold regions and recommend further research.
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