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The stability of artificial sand-binding vegetation determines the success or failure of restoration of degraded ecosystem, accurately evaluating the stability of artificial sand-binding vegetation can provide evidence for the future management and maintenance of re-vegetated regions. In this paper, a novel data-driven evaluation model was proposed by combining statistical methods and a neural network model to evaluate the stability of artificial sand-binding vegetation in the southeastern margins of the Tengger Desert, where the evaluation indexes were selected from vegetation, soil moisture, and soil. The evaluation results indicate that the stability of the artificially re-vegetated belt established in different years (1956a, 1964a, 1981a, and 1987a) tend to be stable with the increase of sand fixation years, and the artificially re-vegetated belts established in 1956a and 1964a have almost the same stability, but the stability of the artificially re-vegetated belt established in 1981a and 1987a have a significant difference. The evaluation results are reliable and accurate, which can provide evidence for the future management of artificial sand-binding vegetation.

Accurate estimation of evaporation is of great significance for understanding regional drought, and managing and applying limited water resources in dryland. However, the application of the traditional estimation approaches is limited due to the lack of required meteorological parameters or experimental conditions. In this study, a novel hybrid model was proposed to estimate the monthly pan Ep in dryland by integrating long short-term memory (LSTM) with grey wolf optimizer (GWO) algorithm and Kendall-τ correlation coefficient, where the GWO algorithm was employed to find the optimal hyper-parameters of LSTM, and Kendall-τ correlation coefficient was used to determine the input combination of meteorological variables. The model performance was compared to the performance of other methods based on the evaluation metrics, including root mean squared error (RMSE), the normalized mean squared error (NMSE), the mean absolute error (MAE), the mean absolute percentage error (MAPE), and Nash–Sutcliffe coefficient of efficiency (NSCE). The results indicated that the optimal input meteorological parameters of the hybrid Kendall-τ-GWO-LSTM models are the monthly average temperature, the minimum air temperature, the maximum air temperature, the minimum values of RMSE, NMSE, MAE, and MAPE are 38.28, 0.20, 26.62, and 19.96%, and the maximum NSCE is 0.89, suggesting that the hybrid Kendall-τ-GWO-LSTM exhibit better model performance than the other hybrid models. Thus, the hybrid Kendall-τ-GWO-LSTM model was highly recommended for estimating pan Ep with limited meteorological information in dryland. The present investigation provides a novel method to estimate the monthly pan Ep with limited meteorological variables in dryland by coupling a deep learning model with meta-heuristic algorithms and the data preprocessing techniques.

Desert regions are regarded as highly sensitive to climatic changes. In arid and semi-arid desert, photosynthetic organisms from biological soil crusts are poikilohydric and sensitive to fluctuations in precipitation. How do physiological properties such as concentration of biochemical constituents and enzymes respond to a precipitation gradient from semi-arid to arid desert regions? We sampled cyanobacteria and moss crusts from four desert regions with distinctly different amounts of annual rainfall. Subsequently, the contents of photosynthetic pigments, malondialdehyde (MDA), osmotic adjustment substances, and antioxidative enzyme activities were correlated with the means of annual precipitation, evaporation, and temperature at the various sites. Crust type, precipitation level, and their interaction had significant influences on many physiological properties (photosynthetic pigments, proline, soluble sugar, and superoxide dismutase). The contents of soluble protein, proline, and soluble sugar of cyanobacteria/moss crusts decreased with increasing precipitation level. Superoxide dismutase and catalase activities of cyanobacteria crusts decreased significantly with increasing annual precipitation. No significant variations in MDA were observed between different precipitation regions in the two crusts. Among the environmental variables tested, the annual amount of precipitation had the strongest effect on the physiological properties of moss/cyanobacteria crusts in different regions. Crust type combined with particular precipitation level influenced the physiological properties of crusts. Moreover, both moss and cyanobacteria crusts exhibited strong physiological adaptability to changes in precipitation. This result needs to be incorporated into future ecological models, which will help in understanding the function and vulnerability of biocrusts in the face of climate change.

Here, we cloned a phytoene desaturase (PDS) gene from Rehmannia glutinosa, and realized RgPDS1 knock out in R. glutinosa resulted in the generation of albino plants. Rehmannia glutinosa is a highly important traditional Chinese medicine (TCM) with specific pharmacology and economic value. R. glutinosa is a tetraploid plant, to date, no report has been published on gene editing of R. glutinosa. In this study, we combined the transcriptome database of R. glutinosa and the reported phytoene desaturase (PDS) gene sequences to obtain the PDS gene of R. glutinosa. Then, the PDS gene was used as a marker gene to verify the applicability and gene editing efficiency of the CRISPR/Cas9 system in R. glutinosa. The constructed CRISPR/Cas9 system was mediated by Agrobacterium to genetically transform into R. glutinosa, and successfully regenerated fully albino and chimeric albino plants. The next-generation sequencing (NGS) confirmed that the albino phenotype was indeed caused by RgPDS gene target site editing, and it was found that base deletion was more common than insertion or replacement. Our results revealed that zCas9 has a high editing efficiency on the R. glutinosa genome. This research lays a foundation for further use of gene editing technology to study the molecular functions of genes, create excellent germplasm, accelerate domestication, and improve the yield and quality of R. glutinosa.

In water-limited areas, shrubs influence biological soil crust (biocrust) composition and diversity via soil microenvironment alterations and through modifying biotic interactions amongst biocrust taxa. However, the relative contributions of shrubs to biocrust succession and assembly via the biotic and abiotic influences are poorly known. The community composition of biocrusts and soil properties in the interspace and beneath the dominant shrub (Artemisia ordosica) along a biocrust succession sequence were investigated. Biocrust interspecific interactions at a small scale (within shrub) were evaluated based on the co-occurrence pattern using null models. A hypothetical multigroup structural equation model (SEM) was proposed to evaluate the influence of multiple variables on the biocrust richness and to investigate the path variance between successional stages. Along the biocrust succession, shrubs significantly increased the size of bare soil gap by 489%, decreased lichens by 43% and increased soil organic matter by 13%. In years 18, 31and 37, the paths in SEM explained 59% of the variation in richness, only the effect of abiotic amelioration was significant (0.62). In years 54 and 62, the shrubs had direct (0.37) and indirect effect (0.10) via species interaction to biocrust richness. Shrubs directly and indirectly affected the community assembly of biocrusts. Biocrust species interactions are an important driver of biocrust diversity and primarily affect late succession. The increasing influences of shrubs suggests a close relationship between shrub and biocrust components in arid or semiarid ecosystems, with shrubs playing an important role in regulating biocrust assembly and maintaining biocrust richness.

The establishment of artificial sand-binding vegetation is one of the main means for restoring damaged ecosystems that are impacted by global change. This study was conducted to evaluate the influence of environmental factors on ecosystem function (net ecosystem exchange (NEE), evapotranspiration (ET), and water use efficiency (WUE)) in an artificial sand-binding vegetation desert (with dominant shrubs, such as Artemisia ordosica and Caragana korshinskii, and herbaceous plants) in northwestern China. NEE, ET, and meteorological data were observed with the eddy covariance (EC) technique. The random forest (RF) method was used to identify major environmental factors that affected NEE, ET, and WUE. Our results showed that the mean annual NEE, ET, and WUE values were − 112.4 g C m−2, 232.1 mm, and 0.49 g C kg−1 H2O, respectively, during the 2015 to 2018 growing seasons. At the weekly scale, the most important drivers of NEE were the normalized difference vegetation index (NDVI) and soil water content (SWC). Rainfall, SWC, and NDVI were important drivers of ET. WUE was mainly controlled by rainfall and SWC. Linear regression showed that NEE had significant negative relationships with the NDVI and SWC. ET had positive relationships with rainfall, SWC, and the NDVI. WUE had significant negative relationships with SWC and rainfall. These findings indicate that drought inhibited ET more than carbon absorption, thus promoting the WUE of the ecosystem to some extent. The close relation of the ecosystem function to SWC implies that this ecosystem may be critically regulated by future climate change (specifically, changes in rainfall patterns).

Magnetic seizure therapy (MST) has established efficacy in the treatment of depression and a growing evidence base in the treatment of depression. We conducted the first systematic review and meta-analysis of the efficacy of MST in anti-depressive treatment and its impact on cognitive function (INPLASY registration number: INPLASY202170061). We searched for controlled trials published in English between 1 January 2001 to 31 December 2020 in PubMed, EMBASE, Cochrane Library, Web of Science, and PsycINFO databases. The evaluation process strictly followed the Cochrane bias risk assessment tool into the literature, and Meta-analysis was performed according to the Cochrane System Reviewer’s Manual. Data from a total of 285 patients from 10 studies were retained in the quantitative synthesis. The results showed no significant difference between MST and ECT in the antidepressant effect (SDM −0.13 [−0.78;0.52]). Compared with ECT, MST showed shorter recovery time (MD −5.67 [−9.75; −1.60]) and reorientation time (MD −14.67 [−27.96; −1.41]); and MST showed less cognitive impairment on the immediate recall of words (SDM 0.80 [0.35;1.25]), delayed recall of words (SDM 0.99 [0.01;0.74]), visual-spatial immediate memory (SDM 0.51 [0.20;0.83]), visual-spatial delayed memory (SDM 0.57 [0.11;1.02]), and the verbal fluency (SDM 0.51 [0.20;0.83]). Our evidence-based study is the first meta-analysis on the efficacy of MST in anti-depressive treatment and its effect on cognitive function. It showed that the curative effect of MST in anti-depressive treatment is equivalent to that of ECT. Besides, depressive patients with MST benefit more from cognitive function compared with ECT.

Biological soil crusts (BSCs) are widely considered critical for soil fertility in arid ecosystems. However, how microbial communities regulate the C and N cycles during BSC succession is not well understood. We utilized GeoChip 5.0 to analyze the functional potential of bacteria and fungi involved in the C and N cycles of BSCs along a 61-year revegetation chronosequence. The normalized average signal intensities of different functional genes involved in C and N metabolism in 61-year-old BSCs were significantly different from those in younger BSCs and most functional gene subcategories and the corresponding dominant functional populations were derived from bacterial rather than fungal communities. Most C degradation genes (dominated by the starch-degrading gene amyA) were derived from Actinobacteria (mainly Streptomyces) in bacteria, but Ascomycota (mainly Aspergillus) was the key population for lignin degradation (dominated by the phenol oxidase gene) during BSC succession. N cycle genes involved in denitrification (such as narG, nirK/S, and nosZ) and N fixation (nifH) were mainly derived from Unclassified Bacteria, whereas genes involved in ammonification (ureC) were mainly derived from Streptomyces. Moreover, redundancy analysis showed that soil biogeochemical properties were closely related to bacterial and fungal functional gene structures during BSC succession. These findings indicate that bacteria play a crucial role in the regulation of C and N cycles during BSC succession in arid ecosystems, while fungi perform supplementary degradation of lignin, and these communities can successfully stimulate an increase in C and N metabolism in soil during the later successional stages of BSCs.

Despite the important role of biological soil crusts in the soil carbon cycles of desert ecosystems, the responses of soil respiration in biological soil crust-dominated areas to warming are not well understood. The goal of this study was to investigate the expected increases in temperature on soil respiration both diurnally and seasonally in biological soil crust-dominated areas. We used open-top chambers to simulate warming in the Shapotou region in the Tengger Desert, northern China. An automated soil respiration system was used to measure the soil respiration rates in moss-dominated crusts. The measured environmental variables included the precipitation, volumetric soil water content, air temperature and soil temperature at depths of 0, 5, 10, 20, and 50 cm. The response of soil respiration to warming is a function of soil moisture following rainfall in desert ecosystems. Our results showed that 1.5 °C of simulated warming significantly decreased soil respiration, indicating that the inhibition of soil respiration was likely due to the reduction in soil water content at a relatively high temperature. Over daily cycles, hourly soil respiration rates have commonly been related to hourly temperatures. The observed diel hysteresis between hourly soil respiration and temperature resulted in semielliptical hysteresis loops, and the temperature often lagged behind soil respiration for several hours. The lag times between soil respiration and temperature were significantly and positively related to the depth of the soil temperature measurements. The proximate reason for the diel hysteresis between soil respiration and temperature was likely a mismatch between the depth of CO2 production and the depth of the temperature measurements. Our results indicate that warming increases the response of soil respiration to soil water availability in biological soil crust-dominated desert ecosystems. Therefore, the accelerated drying effect of warming on soil respiration and diel soil respiration patterns between soil respiration and temperature at different depths should be considered in future soil carbon cycle models for biological soil crust-dominated desert ecosystems.

This article mainly selects the image data of 4 years, and establishes the corresponding coastline markings and extraction principles based on the field investigation. The specific method is to use the visual method to extract the shoreline of a province in four periods, and use the 908 shoreline method to make a more accurate assessment. The main data are length, location, and soil quality, and finally, the corresponding statistical analysis is carried out. The combination of virtual reality and rehabilitation medicine has long been the current mainstream trend, and the balance rehabilitation training system produced by the combination of the two has an excellent prospect in the future. China’s economy has developed rapidly in recent years, and people’s material living conditions have also been greatly improved. However, the current health status of young people has shown a downward trend, especially in some colleges, primary and secondary schools, and feedback from physical test data. In universities, the physical health indicators of young people are declining year by year. In response to this situation, we must make corresponding countermeasures. At present, China has developed a sports health management software and released it on the Android platform. It mainly uses Bluetooth communication to connect with corresponding health monitoring equipment. The architecture mainly uses spring, and focuses on the mvc programming idea. Use a server to store data on the server side. Using JAVA language to develop communication uses Http language. The ultimate goal of the system development is to improve the physical health of young people as a whole, and to achieve overall psychological and physical health.

Global warming is expected to have profound effects on terrestrial carbon (C) fluxes, consequently influencing future climate. Biocrusts are important sources of C in the C cycle of desert ecosystems, where vascular plants are restricted by limited soil moisture. This study was conducted in order to evaluate the expected increases in temperature on soil respiration in biocrust-dominated areas. In a field warming experiment, we evaluated the impact of increased temperature on soil respiration in biocrust-dominated (moss-crusted and lichen-crusted) areas in Shapotou, China. In addition, the impacts of precipitation, soil temperature, and moisture on soil respiration were investigated. The effect of warming on soil respiration varied with soil water availability. Our results showed that soil respiration in moss-crusted and lichen-crusted areas in the warming treatment was significantly lower than that in the control. The observed inhibition of soil respiration by the increase in soil temperature was likely due to the reduction in soil moisture caused by the increased water evaporation rate under higher soil temperature. Warming also decreased cumulative C release in moss-crusted and lichen-crusted areas. Moreover, cumulative C release showed marked seasonal variations, with the highest C release occurring in summer and the lowest in winter. Over the seasonal cycle, soil respiration rates were positively correlated with precipitation, soil temperature, and volumetric soil water content. The results of this study indicate that warming may increase the sensitivity of soil respiration to water availability in biocrust-dominated areas in desert ecosystems, suggesting that biocrust should be considered in projections of future C budget.

Despite the important role of biological soil crusts in desert ecosystems, the responses of the crustal composition and distribution to changes in both climatic and edaphic factors at different spatial scales are not well understood. The goal of our research was to study the drivers of crustal community diversity at different scales, determine how crustal diversity and distribution patterns are related to abiotic and biotic factors, and identify the characteristics of crustal communities along a precipitation gradient. We investigated the distribution and characteristics of crustal communities based on 457 soil samples that were randomly collected from six desert regions of northern China. These regions represent a precipitation gradient from 450 mm in the east to 80–100 mm in the west. The measured environmental variables included soil moisture, pH, clay and silt content, soil organic carbon (SOC), total N, total P, total K, CaCO3 content, annual and perennial plant cover and crustal variables, including species richness, crustal cover and biomass. An ANOVA analysis, a stepwise regression and a redundancy analysis were used to analyse and interpret the response of biological soil crusts to environmental factors at two spatial scales. Our results showed that the moss distribution and biomass were strongly related to the topsoil moisture content. The highest diversity of cyanobacteria and algae was observed at sites with relatively dry topsoil, and lichen diversity was promoted at sites with fine-textured soils. In addition, the cover and biomass of moss were positively correlated with perennial plant cover and higher topsoil moisture, which was expected because plant cover provides shade for the moss. The cover and biomass of lichens, cyanobacteria and algae were positively correlated with that of annual plants because these plants may create an ideal habitat and provide nutrients. The physiochemical properties of the topsoil greatly influenced the distribution pattern of the crustal communities at the regional scale. The species richness and biomass of the crustal mosses were positively correlated with precipitation, whereas the species richness and biomass of cyanobacteria and algae were negatively correlated with precipitation at the landscape scale. Rainfall largely determined the species richness and cover of the crustal cyanobacteria and mosses, whereas soil properties had a greater impact on the crustal lichens. Future changes to rainfall regimes could result in the conversion of biological soil crusts and further contribute to changes in the structure and functioning of desert ecosystems.

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

Desert herbs, a crucial component of desert ecosystems, are sensitive to water and nutrient availability and therefore to environmental change. We aimed to determine element concentrations in desert herbs and their relationships with life form, taxonomy, climate, and soil environment. We measured concentrations of 11 elements in shoots and roots of 26 dominant desert herb species from 45 sites in a temperate desert. Shoots of desert herbs had greater concentrations of elements related to photosynthesis and water use efficiency (N, P, Mg, K) than roots. Concentrations of these elements (except N and P) were also greater in annual herbs than in perennial herbs. Greater Mg, K, and Na concentrations were observed in shoots of Chenopodiaceae (mostly C4 species) than in Poaceae (mostly C3 species). Soil properties and taxonomy explained 3.6–26 % and 2.8–24 % of the variation in shoot element concentrations, respectively, whereas climate factors explained only 0.05–6.5 % of the variation. Water and nutrient availability, which are affected by environmental change, influence concentrations of mineral elements in desert plants and their biogeochemical cycles in desert ecosystems.

The colonization and succession of diazotrophs are essential for the development of organic soil layers in desert. We examined the succession of diazotrophs in the well-established revegetated areas representing a chronosequence of 0 year (control), 22 years (restored artificially since 1981), 57 years (restored artificially since 1956), and more than 100 years (restored naturally) to determine the community assembly and active expression of diazotrophs. The pyrosequencing data revealed that Alphaproteobacteria-like diazotrophs predominated in the topsoil of our mobile dune site, while cyanobacterial diazotrophs predominated in the revegetated sites. The cyanobacterial diazotrophs were primarily composed of the heterocystous genera Anabaena, Calothrix, Cylindrospermum, Nodularia, Nostoc, Trichormus, and Mastigocladus. Almost all the nifH sequences belonged to the Cyanobacteria phylum (all the relative abundance values >99.1 %) at transcript level and all the active cyanobacterial diazotrophs distributed in the families Nostocaceae and Rivulariaceae. The most dominant active cyanobacterial genus was Cylindrospermum in all the samples. The rank abundance and community analyses demonstrated that most of the diazotrophic diversity originated from the “rare” species, and all the DNA-based diazotrophic libraries were richer and more diverse than their RNA-based counterparts in the revegetated sites. Significant differences in the diazotrophic community and their active population composition were observed among the four research sites. Samples from the 1981-revegetating site (predominated by cyanobacterial crusts) showed the highest nitrogenase activity, followed by samples from the naturally revegetating site (predominated by lichen crusts), the 1956-revegetating site (predominated by moss crusts), and the mobile dune site (without crusts). Collectively, our data highlight the importance of nitrogen fixation by the primary successional desert topsoil and suggest that the N2-fixing cyanobacteria are the key diazotrophs to the nitrogen budget and the development of topsoil in desert, which is critical for the succession of the degraded terrestrial ecosystems.

Age-related declines in photosynthesis and water potentials of revegetated Caragana korshinskii in arid desert regions are likely related to both reduced soil water availability and increased hydraulic resistance in xylem. In addition to soil water depletion, the degradation of revegetated sand-binding shrubs may be attributed to specific biological traits of the plant itself, such as aging. To improve our understanding of the physiological basis of observed age-related changes in photosynthetic capacity and water relations in drought-stressed xerophytic shrubs, we conducted in situ field experiments on juvenile, young-mature and relatively old-growth Caragana korshinskii Kom. during the 2013 growing season. Our results revealed significant age-related changes in gas exchange and water-use characteristics, including decreases in the rates of photosynthesis and transpiration, stomatal conductance, shoot water potential and leaf relative water content and increase in water use efficiency with increasing age. We also found that the gas exchange and water relations of all three age classes of C. korshinskii were similarly and significantly affected by soil and atmospheric water availabilities. We conclude that the age-related changes in photosynthetic capacity and water relations which occur in C. korshinskii are likely related to reduced soil water availability and increased hydraulic resistance in xylem, both of which result in a decline in water potential, stomatal conductance and photosynthetic capacity with increasing age of the shrub.

Such activities as mining, metal ore smelting and the discharging of mining wastes lead to heavy metal contamination. Phytoremediation, including phytoextraction and phytostabilization, has been considered for a long time to be effective in remediating metal-polluted soils. This research assessed the chance of 40 plants (35 species) distributing on mining-influenced sites for phytoremediation purposes. The results showed that total soil Ni, Cu, Cd, Cr and Co concentrations were in the ranges of 107–3045, 116–2580, 7.1–22.7, 115–897 and 23.2–144.3 mg kg−1, respectively, whereas heavy metal contents in plants were in the ranges of 0.60–435.61, 2.41–298.31, 0.03–32.10, 0.08–88.20 and 0.11–28.52 mg kg−1, respectively. Therefore, no species can be used for phytoextraction purposes because no hyperaccumulator was identified. Salsola passerine, Stipa capillata, Cynanchum Chinense and Halogeton glomeratus with translocation factor (TF) > 1 for all five metals were considered to be accumulators. All plants were observed to hold a bioconcentration factor (BCF) 1, reflecting its low metal accumulation potential. Among the species studied, Oxytropis aciphylla, Salix matsudana, Tamarix hispida, Robinia pseudoacacia, Picea crassifolia, Lycium barbarum and Phragmites communis had both a BCF and TF

Time synchronization is an essential building block of sensor network systems. In this paper, we present a comprehensive study of least squares algorithms for time synchronization in sensor networks, with a focus on continuous monitoring and data collection applications. We propose a set of algorithms to address a number of issues in practical implementation on typical low-cost sensor network platforms, including a scaled signal model to achieve numerical stability in an ill-conditioned problem, sequential estimators for the scaled signal model to reduce computational complexity, a fast initialization scheme to improve energy efficiency, and outlier detection algorithms to improve robustness in long-term autonomous operations. The proposed algorithms are implemented and a measurement-based simulation method is employed to study the performance.

Biological soil crusts (BSCs) are an important type of land cover in arid desert landscapes and play an important role in the carbon source-sink exchange within a desert system. In this study, two typical BSCs, moss crusts and algae crusts, were selected from a revegetated sandy area of the Tengger Desert in northern China, and the experiment was carried out over a 3 year period from January 2010 to November 2012. We obtained the effective active wetting time to maintain the physiological activity of BSCs based on the continuous field measurements and previous laboratory studies on BSCs photosynthesis and respiration rates. And then we developed a BSCs carbon fixation model that is driven by soil moisture. The results indicated that moss crusts and algae crusts had significant effects on soil moisture and temperature dynamics by decreasing rainfall infiltration. The mean carbon fixation rates of moss and algae crusts were 0.21 and 0.13 g C/(m2·d), respectively. The annual carbon fixations of moss crusts and algae crusts were 64.9 and 38.6 g C/(m2·a), respectively, and the carbon fixation of non-rainfall water reached 11.6 g C/(m2·a) (30.2% of the total) and 8.8 g C/(m2·a) (43.6% of the total), respectively. Finally, the model was tested and verified with continuous field observations. The data of the modeled and measured CO2 fluxes matched notably well. In desert regions, the carbon fixation is higher with high-frequency rainfall even the total amount of seasonal rainfall was the same.

Biological soil crusts (BSCs) are an important cover in arid desert landscapes, and have a profound effect on the CO2 exchange in the desert system. Although a large number of studies have focused on the CO2 flux at the soil–air interface, relatively few studies have examined the soil CO2 concentration in individual layers of the soil profile. In this study, the spatiotemporal dynamics of CO2 concentration throughout the soil profile under two typical BSCs (algae crusts and moss crusts) and its driving factors were examined in a revegetated sandy area of the Tengger Desert from Mar 2010 to Oct 2012. Our results showed that the mean values of the vertical soil CO2 concentrations under algal crusts and moss crusts were 600–1,200 μmol/mol at the 0–40 cm soil profiles and increased linearly with soil depth. Daily CO2 concentrations showed a single-peak curve and often had a 1–2 h time delay after the maximum soil temperature. During the rainy season, the mean soil CO2 concentration profile was 1,200–2,000 μmol/mol, which was 2–5 times higher as compared to the dry season (400–800 μmol/mol). Annually, soil moisture content was the key limiting factor of the soil CO2 concentration, but at the daily time scale, soil temperature was the main limiting factor. Combined with infiltration depth of crusted soils, we predicted that precipitation of 10–15 mm was the most effective driving factor in arid desert regions.

Soil water repellency (WR) is an important physical characteristic of soil surface. It is capable of largely influencing the hydrological and geomorphological processes of soil, as well as affecting the ecological processes of plants, such as growth and seed germination, and has thus been a hot topic in recent research around the world. In this paper, the capillary rise method was used to study the soil WR characteristics of Nitraria tangutorun nebkhas. Soil water repellencies at different succession stages of Nitraria tangutorun were investigated, and the relationships between soil WR and soil organic matter, total N, and total P, soil texture, pH, and concentrations of CO3 2- , HCO3 - , Cl - , SO4 2- , Na + , K + , Ca 2+ and Mg 2+ were discussed. Soil WR may be demonstrated at the following nebkhas dune evolvement stages: extremely degraded>degraded>stabilized>well developed>newly developed>quick sand. Apart from some soil at the bottom, the WR of other soils (crest and slope of dune) was found to be largest at the topsoil, and decreased as the soil depth increased. The results showed that multiple factors affected soil WR characteristics, e.g. WR increased significantly as the contents of soil organic matter and total N increased, but did not change as the total P content increased. Soil texture was a key factor affecting soil WR; soil WR increased significantly as clay content increased, and decreased significantly as sand content increased. Low pH was shown to be more suitable for the occurrence of soil WR. Four cations (Ca 2+ , Mg 2+

Soil water is the key abiotic limiting factor in desert areas and hydrological processes determine the vegetation composition, patterns and processes in desert regions. The hydrological processes can be altered by vegetation succession. In this paper, we review the major advances in ecohydrological research and their potential impact on plant-water relations in revegetated desert communities. The major advances in ecohydrological research over the past 50 years in desert areas were analyzed using a case study that investigated the long-term ecosystem effects of sand-binding vegetation in the Tengger Desert. Key challenges and opportunities for ecohydrology research in the future are also discussed in the context of the major scientific issues affecting sand binding vegetation.

The effect and safety of catgut implantation at acupoints o treat allergic rhinitis (ICD-10 code J30.4) remain controversial. Here, we used a sham catgut implantation group to determine whether catgut implantation at acupoints is an effective and safe treatment for allergic rhinitis. A randomized double-blind clinical trial, with parallel groups was conducted. Skin prick and puncture test (SPT) was performed to confirm the diagnosis before enrollment. The participants received two sessions of treatments of active or sham catgut implantation at acupoints (once every two weeks) with a follow-up phase of 8 weeks. The visual analogue scale (VAS) and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) were used to determine the severity of allergic rhinitis. The use of anti-allergic medication was used as a secondary indicator. The incidence of adverse events was also recorded and analyzed. An improvement of the VAS and RQLQ scores was observed in both the active and sham-controlled group sat four and eight weeks after the treatment in the self-control analysis. Comparison revealed no significant difference between the treatment and sham-controlled groups until 8 weeks after the 2-week treatment regimen (t = −2.424, P = 0.017). However, the RQLQ scores significantly differed between the two groups after 4 weeks of treatment completion (t = −2.045, P = 0.05) and this difference lasted until the end of 8-week follow-up (t = −2.246, P = 0.033). Throughout the treatment regimen, none of the participants took any relief medication, and no severe adverse events occurred. Our findings suggest that catgut implantation at acupoints is an effective and safe method for symptomatic treatment of allergic rhinitis. Chinese Clinical Trial Registry ChiCTR-TRC- 12002191 (Date of Registration: 2012-05-09)

Explore how soil CO2 efflux and its components change after moving sand dunes are stabilized with shrubs, and how abiotic factors affect those components at different scales. Soil CO2 efflux from a sand-stabilized area was compared to that from moving sand dunes in the Tengger Desert. To partition rhizosphere respiration (RR) from soil basal respiration (RB), a root-isolation plot was established. Compared to moving sand dunes, total soil respiration (RT) in the sand-stabilized area increased 3.2 fold to 0.28 ± 0.08 μmol CO2 m-2 s-1, two thirds of which was from RB. Shrub patchiness produced spatial variation in soil respiration, whereas temporal dynamics of soil respiration were affected mainly by soil water content. Shallow soil water content (0–20 cm) influenced RT and RB, whereas deep soil water content (30–210 cm) influenced RR and the ratio RR/RT. During most of the year when soil water content was below field capacity, diurnal changes in soil respiration were partially decoupled from soil temperature but could be modeled using soil temperature and photosynthetic active radiation. Sand-dune stabilization increased soil respiration, and increased RB from biological soil crust and altered soil properties such as increased soil organic matter contributed more than increased RR from increased shrubs.

Desert characterized by alkaline soil with low organic matter and nutrients has a high soil oxidative potential. We hypothesized that oxidase activities would recover faster than hydrolases during the succession of sand-fixing community. Sand dunes stabilized in different years, including a moving sand dune and a steppe at the southeastern fringe of the Tengger Desert, were selected to investigate restoration of extracellular enzyme activities (EEAs) in a 50-year chronosequence. Oxidases showed significantly higher activities than hydrolases at all ten studied sites and EEAs exibited a decreasing trend from catalase, phenol oxidase, sucrase, urease, alkaline phosphatase, α-Amylase to cellulase. After 50 years of revegetation, most EEAs in topsoil recovered to 50–83% of that of the steppe except for urease. Oxidase activities recovered earlier and faster than hydrolases, while hydrolases activities attained the fastest recovery at 19–25 years in the 50-year chronosequence. Recovery of EEAs was modulated by the succession of the sand-fixed community: oxidases activities exhibited peak recovery rates at the stage when shrubs dominated the community, while recovery of hydrolases activities appeared to be mainly regulated by biological soil crusts and annual plants.

Special Issue Guest Editorial

Programmed cell death (PCD) is an active cellular suicide that occurs both in animals and plants throughout development and in response to abiotic or biotic stress. In contrast to plant hypersensitive response-like cell death, little is known about the molecular machinery that regulates the halophyte plant PCD under high salinity stress. Since mitogen-activated protein kinases (MAPKs) are involved in plant response/tolerance to salt stress, and plant MAPK genes belong to the extracellular signal-regulated kinase (ERK) subfamily, we have investigated the role of ERK-like enzymes in high salinity stress-induced cell death in Thellungiella halophila. The data showed that ERK-like enzymes were early (10 min) and transiently activated under 300 mM NaCl stress. Pretreatment with 10 μM U0126, a special MEK/ERK inhibitor, resulted in a small but statistically significant increase of the percentage of terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL)-positive nuclei in contrast to salt alone. The effects of U0126 on H2O2 production and cytochrome c (cyt c) release were also investigated. We found that the pretreatment with U0126 accelerated H2O2 production as well as cyt c release, and eventually enhanced cell death. The results suggest that ERK-like enzymes in Thellungiella halophila may act as a positive regulator of salt tolerance, as illustrated by pretreatment with U0126 which enhanced cell death under high salinity stress.

The present study showed the toxicity caused by heavy metal and its detoxification responses in two desert plants: perennial Peganum harmala and annual Halogeton glomeratus. In pot experiments, 1-month-old seedlings were grown under control and three levels of combined heavy metal stress. Seedling growth as well as heavy metal accumulation, antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX)] activities and the contents of malondialdehyde (MDA), and hydrogen peroxide (H2O2) in leaves was examined after 2 months of heavy metal exposure. Compared with H. glomeratus, growth of P. harmala was more severely inhibited. In leaves, the heavy metal accumulation pattern in both the plants was dose-dependent, being more in H. glomeratus. H. glomeratus exhibited a typical antioxidative defense mechanism, as evidenced by the elevated activities of all the three enzymes tested. P. harmala exhibited a different enzyme response pattern, with a significant reduction in CAT activity, and elevated SOD and APX activities, but significantly elevated APX activity was only at the lowest heavy metal concentration. MDA and H2O2 contents were significantly enhanced in leaves of heavy metal-treated P. harmala, but in H. glomeratus were elevated only at the highest heavy metal treatment. These results indicated that H. glomeratus had a greater capacity than P. harmala to adapt to oxidative stress caused by heavy metal stress, and antioxidative defense in H. glomeratus might play an important role in heavy metal tolerance.

Wireless sensor networks (WSNs) have great potential to revolutionize many science and engineering domains. We present a novel environmental monitoring system with a focus on overall system architecture for seamless integration of wired and wireless sensors for long-term, remote, and near-real-time monitoring. We also present a unified framework for sensor data collection, management, visualization, dissemination, and exchange, conforming to the new Sensor Web Enablement standard. Some initial field testing results are also presented. The monitoring system is being integrated into the Texas Environmental Observatory infrastructure for long-term operation. As part of the integrated system, a new WSN-based soil moisture monitoring system is developed and deployed to support hydrologic monitoring and modeling research. This work represents a significant contribution to the empirical study of the emerging WSN technology. We address many practical issues in real-world application scenarios that are often neglected in the existing WSN research.

Shrub species are considered the dominant plants in arid desert ecosystems, unlike in semiarid steppe zones or in grassland ecosystems. On the Alxa Plateau, northern China, sparse vegetation with cover ranging from 15% to 30% is characterized mainly by multifarious shrubs because herbaceous species are strongly restricted by the extreme drought climate, wind erosion, overgrazing and sand burial. Patterns in shrub species richness and species abundance in relation to environmental conditions were examined by DCA (detrended correspondence analysis) and interpreted by a biplot. The relationships between species diversity and environmental factors were examined using regression analyses. Our results show that the distributions of the shrub species in response to environmental conditions can be grouped into four ecological types, corresponding with the biological traits of the shrubs and their responses to the gradients of soil texture and soil water content. Patterns in species richness and species abundance were mainly determined by the deeper soil water content, instead of the soil texture as hypothesized by numerous studies in semiarid grasslands. With exception of the deeper soil water content, soil organic matter and total N content were positively correlated with species abundance, while pH was negatively correlated with it. These findings imply that it is vital for current shrub diversity conservation to reduce agricultural water use in the middle reaches of the Heihe River, which supplies water for the lower reaches in the western parts of the plateau, and to reduce the amount of groundwater exploitation and urban and oasis water use, to increase the water supply from Helan Mountain to the eastern desert of the Alxa Plateau.

The Oasis-desert ecotone plays an important role in ensuring oasis ecological security. This study was to determine the main factors on the changes of desert vegetation in the oasis-desert ecotone, and to understand the mechanisms of the long-term changes. During past 50 years, the dominant plant species of Tamarix-vegetation in the Minqin oasis-desert ecotone changed from mesophytes to xerophytes and finally to super-xerophytes. The vegetative distribution area (belt width of Tamarix-vegetation between desert and oasis) markedly decreased from 1,000 m past to 30 m current. The coverage of Tamarix bushes reduced from 25 to 7%. The importance value (IV) of the bushes fell from 0.957 to 0.752, and Simpson index decreased from 0.702 in 1959–0.589 in 1992, and then increased to 0.712 in 2002. These changes in vegetation were closely related with the rapid decrease of groundwater table and the reduction of soil moisture due to unsustainable use of water resources for expanded agriculture development. These findings suggested that the change of Tamarix-vegetation in the oasis-desert ecotone was a process of vegetation degradation and concurrent desertification. The maintaining of stable groundwater and Tamarix-vegetation is a vital prerequisite for dryland management, especially, conserving ecological health of oasis-desert systems.

Desert shrubs, a dominant component of desert ecosystems, need to maintain sufficient levels of nutrients in their different organs to ensure operation of various physiological functions for the purpose of survival and reproduction. In the present study, we analyzed 10 elements in leaves, stems and roots of 24 dominant shrub species from 52 sites across a temperate desert ecosystem in northwestern China. We found that concentrations of all 10 elements were higher in leaves than in stems and roots, that non-legumes had higher levels of leaf Na and Mg than did legumes and that Na was more concentrated in C4 leaves than in C3 leaves. Scaling relationships of elements between the photosynthetic organ (leaf) and non-photosynthetic organs (stem and root) were allometric. Results of principal components analysis (PCA) highlighted the important role of the elements responsible for osmoregulation (K and Na) in water utilization of desert shrubs. Soil properties and taxonomy explained most variation of element concentrations in desert shrubs. Desert shrubs may not be particularly susceptible to future change in climate factors, because most elements (including N, P, K, Ca, Mn, Zn and Cu) associated with photosynthesis, osmoregulation, enzyme activity and water use efficiency primarily depend on soil conditions.

The presence of biological soil crusts can affect the germination and survival of vascular plants, but the reasons are not well investigated. We have conducted a field investigation and greenhouse experiments to test the effect of crusts on two desert annual plants, which occur on the stabilized dunes of the Tengger Desert in N China. The results showed that biological soil crusts negatively influenced the seed bank of Eragrostis poaeoides and Bassia dasyphylla. The important effect of biological soil crusts on seed germination and establishment were performed indirectly through reducing the amount of germinating seeds. Field investigation and experimental results with regard to the seed bank indicated that higher seedling density was found in disturbed crust soil and bare soil surface than in intact crust soils. Greenhouse experiments showed that the effects of biological soil crusts on germination and establishment of the two plants are not obvious in moist condition, while disturbed crusts are more favorable to seed germination in dry treatment. Significant differences in biomass were found between disturbed crust soil and bare soil. Survival and growth of the two annual plants were enhanced in both algal and moss crusts during the season of rainfall or in moist environment, but crusts did not affect seedling survival in the dry period. The small seeded E. poaeoides has higher germination than larger-seeded B. dasyphylla in crust soils, but B. dasyphylla has a relatively higher survival rate than E. poaeoides in crust soils.

The integration of location information with day-to-day applications will grow significantly over the next decade as the technology’s accuracy evolves. Currently outdoor localization, thanks to the Global Positioning System (GPS), has revolutionized navigation-based applications running on automotive GPS-enabled devices and smart phones. Applications range from guiding drivers to their destinations to providing point-by-point directions to the closest cinema or coffee shop. The success of GPS has been due to the reliability, availability, and practical accuracy that the orbiting satellites covering the globe provide. However, GPS provides limited coverage indoors and poor quality information in urban areas and near buildings which has motivated research in indoor geolocation in the last decade. A major challenge facing the indoor localization industry is the indoor propagation problem. The indoor environment is not friendly to wireless signals and that is manifested through limited coverage, multipath propagation, and the non-line-of-sight (NLOS) problem. Many research areas developed in the last decade to address those challenges. A fundamental aspect to addressing the challenges is understanding the indoor propagation mechanisms affecting the accuracy of localization; and efforts to measure, characterize and model the wireless channel from a geolocation perspective have received significant attention. Further algorithms and techniques to mitigate the multipath and NLOS problems have emerged recently for many systems (e.g. WLAN, WSN, UWB, etc.). Another area of research that has evolved around the indoor problem is the inertial measurement unit (IMU) based approaches in navigation and tracking (e.g. Kalman filters, particle filters, etc.) which adds another dimension to indoor location estimation. Finally hybrid technologies and signals of opportunity approaches have gained popularity recently to harness the most available information in order to improve robustness and accuracy of indoor localization systems. Although many approaches have been investigated and proposed, accurate indoor location remains a challenging problem. This special issue aims at attracting research papers focusing on mitigating the indoor geolocation challenges. The annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) is one of the premier conferences in the wireless research arena and has a long history of bringing together academia, industry and regulatory bodies. Today, it has become one of the IEEE Communication Society’s flagship conferences in telecommunications. The 23rd IEEE PIMRC was held successfully in Sydney Australia, from 9 to 12 September 2012, where several hundred researchers met to share their latest research results in wireless technologies. In this special issue, we have compiled the extended versions of the best papers on indoor geolocation techniques from this conference as well as a few invited papers from wellknown experts in this field. The invited authors have done an excellent job in substantially extending the conference version of the papers, which significantly improved the X. Li (&) Department of Electrical Engineering, University of North Texas, Denton, TX, USA e-mail: xinrong.li@unt.edu

Taking annual plant Eragrostis poaeides in the artificial vegetation-stabilized sand dune in the Shapotou Experimental Research Station as example, study has been done on the adaptation strategies of annual plants to random environment through fixed quadrat observations of population changes and fixed plant determinations of individual growth, seed germination, population dynamics, spatial distribution pattern of population, competition and regulation. During the growing season, the survival rate of annual plants depends on the precipitation intensity and precipitation duration which activate the germination of seeds. The optimal germination strategy of annual plants in this habitat during the growing season appears as continuous germination under suitable conditions. Such continuous germination is an adaptive characteristic of annual plants to random environment. In addition, the variation processes of population size and regulation mechanism of E. poaeoides are studied. Statistical results of natural population in four consecutive years show that water condition in the habitat is the leading factor affecting the population dynamics of E. poaeoides. During the establishment period E. poaeoides had a higher death rate, but in the middle to later period they could survive stably. Due to the limitation of soil moisture, the competition among individuals for water inevitably led to self-thinning phenomena. Under very arid condition, the survival curve of annual herbs entirely appears as Deevey III type (C type), but under relatively adequate precipitation condition, the survival curve appears as intermediate type. The strategy of life history obviously appears as r-strategy. Plant species of r-strategy often occurs in the early succession stage of the communities. In the relatively adequate and evenly-distributed rainfall years, E. poaeoides population exhibited a density-dependent, i. e., survival rate increased with decrease in population density. The main pattern to regulate the population number for the intraspecific competition is to regulate the highly variable initial density into a final density with narrow variation range.

Most wireless devices manufactured today are equipped with a plurality of sensors and communication capabilities. Handheld devices can nowadays connect through multiple communication networks, such as 3G/LTE, WiFi, Bluetooth, Zigbee, WiMax, UWB, etc. They are also capable of sensing the environment, taking still images or videos, finding their location, detecting hand movements via accelerometers, and reading RFID tags. These devices have advanced operating systems capable of sophisticated signal processing and wireless communications. Much research is needed to use the sensing and communication capabilities of the newest generation of wireless devices to build new applications such as real-time youtube or wikis that collect, process, and report live data to public for security, news, or entertainment purposes. Among the applications envisioned for the new technology are vehicular networks, assistive technologies, eHoming (smart home), and the entertainment industry. The powerful capabilities of new smart phones and PDAs motivate new directions in academic research that seek to fully harvest the potential of advanced features for the creation of new network services. Most such emerging services will need the user location, which is not usually trivial to obtain. Interesting applications where location is an important factor for service enabling are assistive technologies, especially for navigation of visually impaired, vehicular safety enhancement, event and situation-aware services, and so on. Despite much effort in recent years on location estimation both using active and passive methods, location estimation remains to be a challenging problem, especially in indoor environments where GPS signal is not available or the GPS location estimate is fairly inaccurate. This special issue tries to address some of the challenges in the location estimation and offer solutions where available. The annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) is one of the premier conferences in the wireless research arena and has a long history of bringing together academia, industry and regulatory bodies. Today, it has become one of the IEEE Communication Society’s flagship conferences in telecommunications. The 22nd IEEE PIMRC was held successfully in Toronto, Canada, from September 11 to 14, 2011, where over 600 researchers met to share their latest research results in wireless technologies. In this special issue, we have compiled the extended versions of the best papers on localization from this conference as well as a few invited papers from well-known experts in this field. The invited authors have done an excellent job in substantially extending the conference version of the papers, which significantly improved the quality of the manuscripts. The objective of this special issue is to provide the readers a timely perspective on the exciting new developments in the field of wireless localization technologies. The first paper, ‘‘A Comprehensive Tutorial on Localization: Algorithms and Performance Analysis Tools’’ by Davide Macagnano, Giuseppe Destino, and Giuseppe Abreu, was originally presented at PIMRC 2011 as a tutorial. The authors diligently converted the half-day tutorial presentation into a long tutorial article to provide a comprehensive view of technological solutions and theoretical fundamentals of localization and tracking (LT) systems for wireless S. Valaee Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada e-mail: valaee@comm.utoronto.ca

Background Acupuncture has been used in China to treat tinnitus for a long time. There is debate as to whether or not De Qi is a key factor in achieving the efficacy of acupuncture. However, there is no sufficient evidence obtained from randomized controlled trials to confirm the role of De Qi in the treatment of acupuncture for tinnitus. This study aims to identify the effect of De Qi for patients who receive acupuncture to alleviate tinnitus by a prospective, double-blind, randomized, sham-controlled trial. Methods and design This study compares two acupuncture groups (with or without manipulation) in 292 patients with a history of subjective tinnitus. The trial will be conducted in the Teaching Hospital of Chengdu University of Traditional Chinese Medicine. In the study, the patients will be randomly assigned into two groups according to a computer-generated randomization list and assessed prior to treatment. Then, they will receive 5 daily sessions of 30 minutes each time for 4 consecutive weeks and undergo a 12-week follow-up phase. The administration of acupuncture follows the guidelines for clinical research on acupuncture (WHO Regional Publication, Western Pacific Series Number 15, 1995), and is performed double-blind by physicians well-trained in acupuncture. The measures of outcome include the subjective symptoms scores and quantitative sensations of De Qi evaluated by Visual Analog Scales (VAS) and the Chinese version of the ‘modified’ Massachusetts General Hospital Acupuncture Sensation Scale (C-MMASS). Furthermore, adverse events are recorded and analyzed. If any subjects are withdrawn from the trial, intention-to-treat analysis (ITT) and per-protocol (PP) analysis will be performed. Discussion The key features of this trial include the randomization procedures, large sample and the standardized protocol to evaluate De Qi qualitatively and quantitatively in the treatment of acupuncture for tinnitus. The trial will be the first study with a high evidence level in China to assess the efficacy of De Qi in the treatment of tinnitus in a randomized, double-blind, sham-controlled manner. Trial registration Chinese Clinical Trial Registry: ChiCTR-TRC-14004720 (6 May 2014).

Species traits, environmental gradients, and distribution pattern could be three main tools providing mechanistic understanding of ecosystems, predicting the key issues in ecological stability, balance, and succession orientation. Present study is focused on a desert-oasis area, characterized by possible two abiotic environmental gradients and the distribution of seven plant species dominating four types of sand dunes. Aim of this study is to find the desert survival mechanisms for sand-binding application. Within the accessions of this transitional belt, three major types of water use characteristics could be defined. Dominant species including shrubs and herbs were significantly negatively correlated with their diurnal transpiration at rhizosphere moisture (P