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Background With the increasing fragmentation of landscape induced by rapid urbanization, the construction of ecological networks is of great significance to alleviate the degradation of urban habitats and protect natural environments. However, there is considerable uncertainty when constructing ecological networks, especially the different approaches to selecting ecological sources. We used the southern Chinese city of Shenzhen as a study area to construct and optimize ecological networks using a coupling approach. Ecological source areas were extracted using morphological spatial pattern analysis (MSPA) and the landscape index method. Ecological networks were constructed using the minimal cumulative resistance (MCR) model and the gravity model. Stepping stones and ecological fault points were added in corridors to optimize the ecological network. Results Ten core areas with maximum importance patch values were extracted by the landscape index method as ecological source areas according to MSPA, after which corridors between ecological sources were constructed based on the MCR model. The constructed ecological networks were optimized using 35 stepping stones and 17 ecological fault points. The optimized ecological networks included 11 important corridors, 34 general corridors, and seven potential corridors. The results of corridor landscape-type analysis showed that a suitable ecological corridor is 60 to 200 m wide. Conclusions Overall, our results imply that ecological source areas can be identified virtually, and that ecological networks can be significantly optimized by combining MSPA and MCR models. These results provide a methodological reference for constructing ecological networks, and they will be useful for urban planning and biodiversity protection in Shenzhen and other similar regions around the world.

Shrub encroachment is very common in the semiarid regions of China. However, surprisingly little research has been conducted to evaluate the effects of shrubs on soil properties in these regions co...

Vegetation canopy interception (Ic) of precipitation is a considerable component of the global hydrological cycles. Although the measurement and modeling of canopy interception have been explored worldwide at the individual, stand or ecosystem scale, it is still unclear how to recognize this process at the regional or global scales within the context of global climate change. In this study, a revised Gash model was employed to estimate canopy interception based on remote sensing and meteorological data. The spatial and temporal variations in Ic were investigated and the main environmental factors were explored in China for the 2000–2018 period. The results showed that the revised Gash model performed well in modeling canopy interception at the regional scale compared with the PML_V2 dataset product and the in-situ measurements. The average annual Ic in China from 2000 to 2018 was 166.55 mm, with a significant decreasing spatial pattern from the Southeastern to the Northwestern regions. The ratio of canopy interception to precipitation (Ir) displayed a similar spatial pattern, with an average value of 22.30%. At the temporal scale, the mean annual Ic significantly increased at a rate of 1.79 mm yr−1 (p < 0.01) during the study period, and the increasing trend was more pronounced during the 2000–2009 period, at a rate of 3.34 mm yr−1 (p < 0.01). In most vegetation types, except for the deciduous broad-leaved forest and temperate desert, canopy interception showed a significant increasing trend (p < 0.01). Precipitation, temperature, and the normalized differential vegetation index (NDVI) were considered to be the main factors affecting the variations of Ic in China during the last two decades, with specific dominant factors varying in different areas. Specifically, precipitation was considered to control the variations of Ic in the Northwestern regions, temperature mainly influenced the Southern regions, and the NDVI was identified as the main factor in regions where significant ecological conservation projects are established, such as the Loess Plateau. Our findings are expected to not only contribute to the understanding of regional ecohydrological cycle but also provide valuable insights into the methodology of interception modeling at the regional and global scales.

The rapid development of urbanization has caused many ecological issues and greatly threatened the sustainable development of human society. The construction of ecological security patterns (ESPs) offers an effective way to balance ecological conservation and urbanization. This study aimed to take the highly urbanized city of Shenzhen, China, as a study area to construct an urban ESP and put forward suggestions for the urban development of ecological security. Ecological sources were identified through the Habitat Quality module in the InVEST model, and ecological corridors, strategic ecological nodes, and stepping-stone patches were extracted based on the minimum cumulative resistance (MCR) model. These elements together constituted the ESP. In particular, with the results of the continuous decline in the overall habitat quality, this study identified ten ecological sources with superior habitat quality, mainly distributed in rural woodlands, in urban green land, and in forest park patches. An optimized pattern for Shenzhen City with one axis, three belts, and four zones is proposed, with the study area divided into an ecological preservation zone, a limited development zone, an optimized development zone, and a key development zone. Moreover, forty-five ecological corridors were extracted and graded into three levels, presenting a spatial pattern of one axis and three belts. The appropriate widths of these ecological corridors were suggested to be between 30 and 60 m in Shenzhen City. In addition, we identified twenty-five ecological nodes, sixteen ecological fracture points, and sixteen stepping stones to improve the maintenance and construction of the ecological corridor network. More generally, this study demonstrates a scientific approach to identifying ESPs based on habitat quality, and can serve as a reference for the planning of urban ecological function regionalization.

Soil water conditions play an important role in the formation of a collapsing gully, but we are still at the early stages of understanding how the soil water changes on the slope after different rainfall events due to a lack of high-frequency continuous field observations. This study aimed to reveal the response of soil water dynamics to rainfall events for different slope aspects and positions based on continuous multi-depth observations of soil water on a typical collapsing gully slope from 2017 to 2019 in Wuhua County, Guangdong Province, China. The vegetation characteristics and soil properties were investigated, and the storage of soil water was also calculated. The results showed that the dynamics and storage of soil water varied with the slope aspect, slope position and vegetation cover. The response time of the soil water to intensive rainfall events on the sunny slope was shorter than that on the shady slope, while soil water storage in the sunny slope was significantly lower than in the shady slope (p &lt, 0.01). For the different slope positions, the soil water response time to the intensive rainfall events on the upper slope was shorter than that in the middle slope, while the soil water storage in the middle slope was significantly higher than on the upper slope. This was mainly due to the redistribution runoff from the upper slope to middle slope, delaying the process by which rainwater infiltrated into the soil layers. Moreover, vegetation significantly allayed the response of soil water dynamics to an intensive rainfall event but increased the storage of soil water, owing to the protection of soil surface from rain and conservation of high soil clay content. The bare area in the middle position of the sunny slope was speculated to be the potential source of the collapsing gully because it lacked the cover of vegetation. Our findings highlight the importance of soil water dynamics on the formation of a collapsing gully and provided valuable insights for the optimization of soil conservation and management practices for collapsing erosion.

Grazing by livestock greatly affects the soil carbon (C) cycle in grassland ecosystems. However, the effects of grazing at different intensities and durations on the dynamics of soil C in its subsoil layers are not clearly understood. Here, we compiled data from 78 sites (in total 122 published studies) to examine the effects of varying grazing intensities and durations on soil C content at different depths for grasslands in China. Our meta-analysis revealed that grazing led to an overall decrease in soil C content and productivity of above-ground vegetation (e.g., above-ground biomass and litter) but an increase in below-ground biomass. Specifically, the effects of grazing on soil C content became less negative or even positive with increasing soil depths. An increase of soil C content was consequently found under light grazing (LG), although soil C content still decreased under moderate and heavy grazing. The increase in soil C content under LG could be largely attributed to the increase of soil C content in subsoil layers (>20 cm), despite that soil C content in surface soil layer (0-20 cm) decreased. Moreover, the magnitude of increase in soil C content under LG in subsoil layers increased with grazing duration. A possible reason of the increase in soil C content in the subsoil layers was due to the increases in below-ground biomass. Our study highlights that LG may modify the allocation of C input and promote its accumulation in subsoil layers, thus offsetting the negative impact of grazing on surface soil C content, a finding that has significant implications for C sequestration in grasslands.

How the presence of biological soil crusts (BSCs) and physical soil crusts (PSCs) regulates surface soil hydrological processes in the high-altitude alpine ecosystems is still a pressing scientific issue owing to a lack of convincing field observation data. This study highlights the interesting phenomenon whereby BSCs and PSCs are jointly distributed in opposite orientations under a canopy of patchy Achnatherum splendens grass on the alpine steppe of the Qinghai Lake watershed (Qinghai-Tibet Plateau, northwestern China). The vegetation characteristics (plant species, cover, and biomass) and soil properties (volumetric soil water content, hydraulic conductivity, temperature, salinity, and macroporosity) were investigated for BSCs zones, PSCs zones, and interpatch zones (IPZs) in the A. splendens patches (ASPs) system. The experimental results show that BSCs increased infiltration during wet periods by increasing significantly greater hydraulic conductivity and macroporosity (p

Rainwater is altered hydrologically and chemically as it passes through tree canopies to reach the soil surface, but this aspect of urban forest ecosystems has received less attention than that of natural ecosystems. Hydrological partitioning and changes in solute composition of rainfall were examined in an urban forest within Guangzhou city, in southern China, with reference to three typical subtropical urban tree species (Roystonea regia, Ficus microcarpa, and Lagerstroemia speciosa) with large but morphologically distinct canopies. Three components of rainfall, namely throughfall, stemflow, and interception, were measured and sampled from September 2018 to September 2019. A canopy budget model was used for estimating the contribution of canopy exchange and dry deposition to net rainfall (throughfall + stemflow) solute flux. Being a palm, R. regia recorded the highest percentages of throughfall (72.60%) and stemflow (8.68%) whereas interception was higher in F. microcarpa (33.48%) and L. speciosa (30.54%). The concentrations of almost all the solutes (Ca2+, K+, Na+, Mg2+, Cl−, NO3−, and SO42−) in throughfall and stemflow were higher than those in rainfall, suggesting that water was enriched with these solutes as a result of passing through the canopy. The model of canopy budget also showed that whereas all the three species were similar in terms of the leaching of macronutrient cations, the species differed in term of anions: whereas R. regia and L. speciosa generally absorbed or retained anions on foliage, twigs, or trunks, F. microcarpa leached Cl− and NO3− (presumably because of its unique aerial root). These results can inform the design of urban forests. For example, the lack of NO3− uptake by F. microcarpa suggests that it would be less suitable for mitigating the problems of N deposition which are significant in southern China than the other two species; on other hand, the rainfall partitioning and canopy exchange characteristics of L. speciosa make it more suitable for intercepting rainwater as well as for alleviating the problem of N deposition. The findings of this study therefore have significant implications for the selection of urban tree species in similar subtropical regions worldwide.

In this work, the effects of the sludge retention time (SRT, 35, 25, or 15 d) and pH (7.5, 8.0, 8.5) on denitrifying phosphorus removal were investigated using denitrifying phosphorus bacteria (DPBs) enriched in a sequencing batch reactor (SBR). The results indicated that shortening the SRT from 35 d to 25 d resulted in a decrease in the mixed liquor volatile suspended solids (MLVSS) from 2821 to 2301 mg·L

The etiology of urticaria is heterogeneous and allergic responses may be involved in it. The aim of the present study was to investigate the prevalence and distribution of sensitivity to inhaled and food allergens among patients with urticaria in Henan province (China). The levels of specific immunoglobulin E (sIgE) were detected using the AllergyScreen test and a total of 524/1,091 cases (48.0%) tested positive for sIgE to at least one of the 19 allergens. The most common inhaled allergens the urticaria patients were sensitive to were D. pteronyssinus (34.5%), cockroach (12.5%) and tree pollen mix (11.1%), while the food allergens with the highest rate of allergic reactions were cashew nut (8.1%), shrimp (6.8%) and crab (6.4%). The positive rates for D. pteronyssinus, dog hair, cockroach, mold mix, tree pollen mix and shrimp in the chronic urticaria group were higher than those in the acute urticaria group (P

Tropical monsoon forest soils have the potential to mitigate global warming by removing methane (CH4) from the atmosphere, yet whether this function would be altered under future precipitation regimes remains unclear. In this study, we conducted two rainfall manipulation treatments, including the delayed wet season (DW) and wetter wet season (WW), since 2012 in a tropical monsoon forest in southern China to investigate the impact of changing precipitation patterns on soil CH4 uptake over two measurement years between 2018 and 2019. We found that DW significantly increased the annual average soil CH4 uptake by 164%, mainly due to a significant increase during the dry season via enhancing soil moisture and soil enzyme activities. Although WW exerted a limited impact on the annual average soil CH4 uptake, it remarkably increased CH4 uptake during the dry season due to the alteration of soil temperature, nutrient conditions, and enzyme activities. Furthermore, we found that methanotrophic abundance increased and decreased with soil moisture during the dry and wet seasons, respectively. The optimum air-filled soil porosity for CH4 uptake was 0.45 m3 m−3. Our results suggested that the role of tropical monsoon forests as CH4 sinks would be enhanced under delayed wet season, which should not be overlooked for determining the global CH4 uptake capacity of forest soils in the future.

The interactions between deep-rooted grass patches and soil hydrological processes are unclear. This study used the deep-rooted grass Achnatherum splendens as an indicator plant to evaluate the relationship between spatial distributions of A. splendens patches and dynamics of soil water and salt using electromagnetic induction (EMI) methods in Qinghai Lake watershed on Qinghai-Tibet Plateau in northwestern China. An experimental plot of size 60 m × 60 m was designed for collecting repeated apparent electrical conductivity (ECa) images. Vegetation and soil properties (e.g. soil water, salinity, hydraulic conductivity and particle composition) were investigated. Results showed that soils in A. splendens patches had greater macroporosity and higher unsaturated hydraulic conductivity compared to interpatch zones. Analysis of temporal stability of ECa images showed that locations near A. splendens patches had greater water and salt contents compared to interpatch zones, and these locations also showed the greater increasing magnitudes. This indicated that A. splendens patches acted as focal points for accumulating soil water since the high and dense crown could trap the aeolian sediments and then improve infiltration capacity of soils. Process of root water uptake of A. splendens promoted salt ions transporting into the root zone, which was thought to be the main reason for the salt accumulation. The deep-rooted A. splendens changed soil hydrological properties and affected the dynamics of soil water and salt, and these eco-hydrological processes were determined using the EMI. Our findings provide valuable insights in understanding the eco-hydrological processes of deep-rooted patchy vegetation.

The spatial patterns and dynamics of soil water and salt at the field scale between rainfall events are not well understood due to a lack of appropriate instruments for measurements. In this study, we conducted time series EMI surveys and then mapped apparent electrical conductivity (ECa) to estimate the relative changes in soil water and salt in an Achnatherum splendens steppe ecosystem in Qinghai Lake watershed, China. The results indicated that ECa could be used as a surrogate for interpreting changes of water and salt content in soil. The ECa images clearly showed that ECa values increased rapidly after rainfall events, and the increased amplitudes of ECa values in soils under A. splendens (AS) were obviously greater than that of soil in the interspaces between A. splendens tussocks (IAS). This demonstrated that rainwater infiltrated faster and in greater quantity into the soils under AS because of their coarse-textured surface soils with greater macroporosity and higher hydraulic conductivity as compared to the interspace soils. Moreover, the increasing salinity in AS and decreasing salinity in IAS after rainfall events suggested that overland flow might perhaps have occurred from the interspaces into A. splendens areas. The temporal stability of ECa maps demonstrated that there was great soil variability at the study plot, especially in soil salt. This study highlighted that the time series ECa images could qualitatively capture dynamics of soil water and salt at the field scale after rainfall events, and it linked the dynamics of soil water and salt to vegetation variability.

Ecosystem water use efficiency (WUE), defined as the ratio of gross primary productivity (GPP) to total ecosystem evapotranspiration (ET), is an important indicator of the coupling between the terrestrial carbon and water cycles. China's Loess Plateau (CLP) has been experiencing climatic warming in recent decades and large-scale revegetation since the early 2000s. Understanding the combined effects of revegetation and climate change on ecosystem WUE patterns is important for a better prediction of future changes of the water and carbon cycles in the region. In this study, we decompose ecosystem WUE into a two-component process, i.e., the ratio of carbon uptake to plant transpiration, GPP/T, and the ratio of plant transpiration to total evapotranspiration, T/ET. Based on this, we investigate the temporal variations of ecosystem WUE and examine the underlying controls of WUE dynamics on CLP during 1985–2015. We find that ecosystem WUE on CLP remains more or less unchanged during 1985–1999 as a result of an increased T/ET that is largely offset by a decreased GPP/T induced by increases in atmospheric vapor pressure deficit. In comparison, ecosystem WUE significantly increases during 2000–2015, owing to the increased leaf area index, which promotes the fraction of plant transpiration over total ET (i.e., T/ET). In facing the upcoming peak of greenness and continuing climate warming, our results suggest that CLP's ecosystem WUE may experience a downward trend in the future due to diminishing positive effects of leaf area index but increasing negative effects of atmospheric vapor pressure deficit. Our study highlights the importance of decomposing ecosystem WUE into component processes to better understand the mechanisms that underlying the changes of ecosystem WUE and to predict future ecosystem WUE dynamics.

The nitrogen and phosphorus removal characteristics during the start-up and the long-term operational stability of an anaerobic/anoxic (A/A) ABR coupled aerobic MBR system treating low C/N domestic wastewater were investigated. The results showed that the denitrifying phosphorus bacteria (DPBs) were successfully enriched within 46 d by controlling the nitrate recycling ratio (increasing from 150% to 300%), with a temperature of 30℃±2℃, volume loading rate of 0.8 kg·(m

Construction of ecological network is important for improving urban ecological environment under the scenarios of rapid urbanization. We extracted the core area with good connectivity as the ecological sources with the methods of morphological spatial pattern analysis (MSPA) and landscape index with Guangzhou City as the study area. The ecological network was then constructed by minimal cumulative resistance (MCR) model and was quantitatively analyzed by gravity model and connectivity indices. After that, an optimized ecological network was finally constructed. The results showed that ten core patches could be used as ecological sources. In addition, eighteen important corridors as well as twenty-seven general corridors were identified, which were mainly distributed in the northeast part of the city. Five more ecological sources and thirteen more planning corridors were suggested under the optimized ecological network. Our results indicated that forests were the main composition of ecological corridors. The appropriate width for the important corridor and planning corridor was 60-100 m and 30-60 m, respectively. Our results provide scientific guidance for designing urban ecological network.构建生态网络对改善快速城市化背景下城市生态环境问题具有重要作用.本研究以广州市为研究区,采用形态学空间分析方法(MSPA)和景观指数法,提取景观连通性较好的核心区作为生态源地,并基于最小累积阻力模型(MCR)构建广州市生态廊道网络,通过重力模型和连通性指数定量分析生态网络结构,最后提出生态网络的优化对策.结果表明: 广州市共有10块核心区可作为生态源地,重要廊道有18条,一般廊道有27条,主要分布在研究区东北部;优化后的生态网络增加了5个生态源地和13条规划廊道,其结构指数有所改善;林地是生态廊道的主要组成景观,重要廊道的适宜宽度为60～100 m,规划廊道的适宜宽度为30～60 m.研究结果可为城市生态廊道规划提供科学参考.

Regional-scale normalized difference vegetation index (NDVI) derived from satellite remote sensing observations and gridded climate data were used to study the seasonal responses and underlying mechanisms of vegetation growth over Tibetan Plateau to Pacific Decadal Oscillation (PDO) at period of 1982-2015, by performing Spearman correlation analysis and enhanced multivariate regression model: structural equation model (SEM). The results showed that there was significant negative correlation between PDO index and mean growing-season (April-October) NDVI over Tibetan Plateau; however, marked seasonal divergence in the relationship between PDO and vegetation growth existed among different seasons. It characterized with stronger negative correlation between PDO and NDVI in autumn than in summer, and winter PDO had significant effect on consequent summer vegetation growth. Additionally, it showed great divergence in control processes of PDO on vegetation growth among different seasons, with significant control of PDO on both temperature and precipitation in summer, and significant control of PDO on temperature only in autumn.利用卫星遥感观测的区域尺度归一化植被指数(NDVI)和格点气候数据,借助Spearman相关分析及基于多变量回归分析的结构方程模型,研究了1982—2015年青藏高原植被生长季节变化对太平洋10年际涛动(PDO)的响应格局及机理过程.结果表明: 青藏高原生长季(4—10月)平均NDVI与PDO指数存在显著的负相关关系,但是PDO与不同季节NDVI之间的关系呈现出明显的季节分异,具体表现为PDO与秋季NDVI的负相关关系强于夏季,且冬季PDO显著影响次年青藏高原夏季植被生长.另外,PDO对青藏高原植被生长的调控过程在季节间存在明显分异,夏季表现为PDO对温度和降水的共同调控,而秋季则以对温度调控为主.

Understanding species-specific changes in water-use patterns under recent climate scenarios is necessary to predict accurately the responses of seasonally dry ecosystems to future climate. In this study, we conducted a precipitation manipulation experiment to investigate the changes in water-use patterns of two coexisting species (Achnatherum splendens and Allium tanguticum) to alterations in soil water content (SWC) resulting from increased and decreased rainfall treatments. The results showed that the leaf water potential (Ψ) of A. splendens and A. tanguticum responded to changes in shallow and middle SWC at both the control and treatment plots. However, A. splendens proportionally extracted water from the shallow soil layer (0-10cm) when it was available but shifted to absorbing deep soil water (30-60 cm) during drought. By contrast, the A. tanguticum did not differ significantly in uptake depth between treatment and control plots but entirely depended on water from shallow soil layers. The flexible water-use patterns of A.splendens may be a key factor facilitating its dominance and it better acclimates the recent climate change in the alpine grassland community around Qinghai Lake.

The yield of stemflow from vegetation is mostly affected by rainfall and canopy structure, but few past studies have paid attention to the dynamics of canopy structure during the growth season. Artemisia ordosica is a typical subshrub, very different from trees and shrubs. Assessing the influence of canopy structure and rainfall on stemflow yield in A. ordosica during the growth season will fill a knowledge gap in our understanding of stemflow yield from subshrub species. This study therefore examined the effects of those two factors on stemflow at two growth stages of A. ordosica, using 20 experimental individuals in the Mu Us sandy land of northern China. It demonstrated that the mean stemflow percentage of gross rainfall (SF%) for this subshrub was 8.56%, and the average funneling ratio was 75.80. The critical control factors of stemflow volumes were rainfall amount and canopy area, which varied greatly during the growth season. The SF% was significantly lower during the reproductive growth stage than during the vegetative growth stage, because of the rapid increase in leaf area index at the former stage. This evaluation of the effects of vegetation growth dynamics on stemflow yield will improve the accuracy of future hydrological models.

Stable isotopic compositions (δ18O and δD) have been utilized as a useful indicator for evaluating the current and historical climatic and environmental changes. Therefore, it is vital to understand the relationship between the stable isotopic contents in lake water and the variations of lake level, particularly in Lake Qinghai, China. In this study, we analyzed the variations of isotope compositions (δ18O, δD and d-excess) in lake water and precipitation by using the samples that were collected from Lake Qinghai region during the period from 2009 to 2012. The results showed that the average isotopic contents of δ18O and δD in lake water were higher than those in precipitation, which were contrary to the variations of d-excess. The linear regression correlations between δ18O and δD in lake water and precipitation showed that the local evaporative line (LEL) in lake water (δD=5.88δ18O-2.41) deviated significantly from the local meteoric water line (LMWL) in precipitation (δD=8.26δ18O+16.91), indicating that evaporative enrichment had a significant impact on isotopic contents in lake water. Moreover, we also quantified the E/I ratio (evaporation-to-input ratio) in Lake Qinghai based on the lake water isotopic enrichment model derived from the Rayleigh equation. The changes of E/I ratios (ranging from 0.29 to 0.36 between 2009 and 2012) clearly revealed the shifts of lake levels in Lake Qinghai in recent years. The average E/I ratio of 0.40 reflected that water budget in Lake Qinghai was positive, and consistent with the rising lake levels and the increasing lake areas in many lakes of the Tibetan Plateau. These findings provide some evidences for studying the hydrological balance or water budget by using δ18O values of lake sedimentary materials and contribute to the reconstruction of paleolake water level and paleoclimate from an isotopic enrichment model in Lake Qinghai.

In this paper, the working mechanism and high characteristics of an InP/InGaAsP uni-traveling-carrier (UTC) double hetero-junction phototransistor (DHPT) has been analyzed. The UTC-DHPT employs a heavy doping base and two hetero-junctions to realize UTC structure to ease the contract between HPT responsivity and HPT working speed. Optical responsivity and optical transit frequency are analyzed physically through illustrated several kinds of paramistic capacitors in BE junction and BC junction under different electrical bias, optical bias and combined electrical and optical bias in this work. The results show that three-terminal (3T) working mode with combined electrical bias and optical bias in base achieves a highest maxim fT of 120GHz at collector current of 30mA and keeps the same optical responsivity (37.5A/W) compared with two-terminal (2T) working mode.

To systematically collect the thrombelastography (TEG)-or thromboelastometry (ROTEM)-related data, and predict to evaluate their values for the prediction of thromboembolic events.Databases including PubMed, Central and Embase were searched for the related clinical trials, and the references were retrieved manually; these included references were assessed qualitatively by the QUADAS-2 tool; finally the enrolled researches were qualitatively analyzed.A total of 15 studies consisting of 293 VTE patients met the inclusion criteria. The overall quality and the accuracy of TEG or ROTEM in predicting VTE varied a lot. Two thirds of the studies displayed that the changes of TEG parameters or ROTEM were related to the occurrence of VTE.The present studies showed that the TEG or ROTEM for predicting the VTE display higher difference in accuracy, therefore, the combination of TEG or ROTEM with other laboratory tests may improve the accuracy of VTE diagnosis.

The Qinghai–Tibet Plateau is a sensitive area of global climate changes, and riparian ecosystems are thought as “hotspots” for climate change adaptation, but little work has been conducted regarding the alpine riparian ecosystems on the Qinghai–Tibet Plateau. We measured evapotranspiration ( ET ) and surface energy fluxes over the riparian shrub Myricaria squamosa Desv., which is widely distributed on the Qinghai–Tibet Plateau but has not been studied until now. The results indicated that annual ET was 390 mm and 503 mm for the period of 2010 to 2011 and 2011 to 2012, respectively, which was higher than the amount of precipitation during the same period. Cumulative ET was lower than the cumulative reference evapotranspiration during the entire experimental period, whereas ET in August was higher than reference evapotranspiration. ET in the growing season occupied over 80% of annual ET with a maximum daily ET of 7.2 mm d − 1 , and the ET in the non-growing season was quite low because of the frozen soil. In general, temperature and net radiation were the key variables controlling daily ET rates for M. squamosa . Annual sensible heat flux ( H ) consumed 60% of net radiation ( R n ) and latent heat flux ( LE ) 40% during the three years of the study. LE occupied the main part of R n from July to September. H was the highest in May and June, then sunk in the mid-growing season, and rebounded the other peak at late September and early October. Daily ground heat flux was positive from April to mid-September, and it was an important heat source of land surface in the winter and spring. This study highlighted that as an alpine riparian ecosystem in a semiarid region, ET and surface energy partitioning of the M. squamosa community are strongly affected by the freeze–thaw cycle, groundwater fluctuation, precipitation pulses and soil water content. We speculate that climate warming has a significant impact on ET process and surface energy partitioning of the M. squamosa community by influencing the freeze–thaw cycle and soil water content.

Riparian zones are vulnerable to water regimes, which alter soil water availability and impact the persistence of riparian plants. However, little is known about the water use patterns of alpine riparian shrubs (e.g., Myricaria squamosa) in response to changes in soil water availability on the Qinghai–Tibet Plateau. This study examined the water-use patterns of M. squamosa along a zone of gradual degradation (light, moderate, and severe), located in the lower reaches of the Shaliu River in the Qinghai Lake watershed. Stable water isotopes (δ2H and δ18O) in xylem water, soil water and groundwater, as well as leaf water potential were monitored during the growing seasons from 2012 to 2013, and quantified the water-use proportions via MixSIAR model. Results showed significant differences in the isotopic signatures of M. squamosa from the light, moderate, and severe degradation sites across seasons, suggesting that M. squamosa exploited different water sources. MixSIAR results also revealed that M. squamosa used high proportions of shallow soil water in the light degradation site (35.4%) compared with the severe degradation sites (13.4%). By contrast, M. squamosa exhibited an ability to shift its water sources and to rely more on groundwater in the severe degradation site across seasons. The contrasting water-use patterns of M. squamosa along the gradual degradation zone were closely linked with the distributions of active root zones when competing for water. Higher predawn leaf water potential (Ψpd) of M. squamosa (mean Ψpd = −2.29 ± 0.7 MPa) was found in the light degradation site and lower Ψpd values in the severe degradation site (mean Ψpd = −3.3 ± 0.8 MPa), suggesting that M. squamosa depended on a high degree of flexible plasticity in water use to alleviate water stress along the gradual degradation. These results linked to water-use patterns and ecophysiological characteristics (e.g., Ψpd) of plants responding to changes in available water are important for informing decision-making management strategies designed to prevent ecological degradation.

Many arid grasslands around the world are affected by shrub encroachment. However, the transition states of shrub-encroached ecosystems are still poorly known, and the effects of human disturbances are difficult to quantify during the transition process. This study investigated plant biomass, community characteristics, and water capturing capability of the shrub and interspace grass patches during the different transition states of Caragana microphylla Lam-encroached grassland in response to the intensity of anthropogenic disturbances. The results indicate that the number of plant species increased with the disturbance intensity at the shrub patches and that the total aboveground biomass (AB) significantly decreased from the slightly disturbed site to the moderately disturbed site, then significantly increased from the moderately disturbed site to the seriously disturbed site. The total belowground biomass (BB) was much greater in the shrub patches than the interspace grass patches at the above three sites. The results also suggest that grass or shrub dominance were alternative stable states in the processes of shrub encroachment but that a threshold existed during state transition. Dye tracing experiments showed that shrubs had higher water capturing capability than grass. The shrubs could capture and transport water to the deeper soil layers in the shrub patches. We speculate that the competitive advantage for biomass and water by shrubs could be reversed for grass if the disturbance intensity does not exceed a threshold value. A continual increase of anthropogenic disturbance would further lower the water capturing capability of grasses, leading to an increase of biomass and the size of shrub patches and a shift in the landscape to a shrub-dominated state, which would be irreversible.

Water is the source of all the creatures on the earth and energy is the main factor driving the world. With the increasing population and global change, water and energy conservation have become worldwide focal issues, particularly in the water-stressed and energy-limited regions. Rainwater harvesting, based on the collection and storage of rainfall runoff, has been widely used for domestic use and agricultural production in arid and semiarid regions. It has advantages of simple operation, high adaption, low cost and less energy consumption. This study reviewed rainwater harvesting systems adopted in the Loess Plateau of China and analyzed water use efficiency (WUE) for various rainwater harvesting techniques. Supplemental irrigation using harvested rainwater could increase crop yield by more than 30%, and WUE ranged from 0.7 to 5.7 kg m −3 for spring wheat, corn and flax, and 30-40 kg m −3 for vegetables. Moreover, energy consumption for rainwater harvesting based on single family was compared with traditional water supply in the city of the Loess Plateau using the life cycle assessment (LCA) method. Results showed that energy consumption yielded per unit harvested rainwater was 25.96 MJ m −3 yr −1 which was much less than 62.25 MJ m −3 yr −1 for main water supply in Baoji City, Shanxi Province, meaning that rainwater harvesting saved energy by 139.8% as compared to the main water supply system. This study highlights the importance and potential of rainwater harvesting for water and energy conservation in the near future.

“Grain for Green Program” (GGP), i.e., re-conversion of cropland into forest or grassland, initiated by Chinese government has a profound impact on mitigating environmental degradation. The objectives of this study were to assess the changes of some soil properties during the processes of re-conversion from cropland to grassland over time in the semiarid steppe region of north China. Two sites with different ages of re-conversion were selected for measurements of organic matter (SOM), total nitrogen (TN) and phosphorus (TP), bulk density (BD) and grain size distribution. Saturated hydraulic conductivity was determined by the constant hydraulic head method and unsaturated hydraulic conductivity by disc infiltrometer at tensions of 30, 60 and 150 mm. Soil water content was measured using the gravimetric method. Wetting front depths in the soil after rainfall were also recorded at the study sites. Natural grasslands had higher belowground biomass than re-converted grasslands. Re-converted grasslands had lower SOM and TN at depths of 0–20 cm and higher saturated hydraulic conductivity at depths of 0–10 cm than natural grassland. The natural grassland soils had higher soil water contents in the surface soil (0–20 cm) and lower soil water contents at deeper depths than re-converted grassland soils. Soil aggregate stability reached the natural steppe level 12 years after re-conversion. The recovery of soil properties after GGP appeared to be slow, and these properties did not return to natural grassland status before cultivation after 12 years of re-conversion.

The niche differentiation of resources among coexisting plants commonly reflects the fundamental functions of plant coexistence in water-limited ecosystems. However, the dynamics of water use patterns by coexisting plants that respond to soil moisture pulses are scarcely known in the semiarid alpine ecosystems of the Qinghai–Tibetan Plateau, particularly for deep-rooted grasses such as Achnatherum splendens in the Qinghai Lake watershed. Hence, we used the stable deuterium isotope method to detect the potential water sources for A. splendens during two growing seasons of 2013 and 2014. Our results indicate that SWC and δD values of shallow soil layer (0–10 cm) showed the highest variations in comparison with those in other soil layers during the growing seasons due to the combined effect of evaporation and precipitation inputs. A. splendens depended largely on shallow soil water availability at the early growing season. At the peak of the growing season, this deep-rooted grass A. splendens and shallow-rooted grass Leymus chinensis showed a high degree of response in the water use source to the changes in soil moisture pulses and shifted their water source from shallow to deep soil layer because water in the shallow soil layer became less available due to a long-time rainless days with strong evaporation effect on the shallow soil layer. In contrast, shallow soil water was utilized by all coexisting plants owing to an abrupt increase in shallow SWC with large events or long-lasting small events. At the late growing season, A. splendens used water from the shallow (0–10 cm) and middle soil layer (10–30 cm), while L. chinensis mainly relied on the shallow soil layer water. Comparatively, shallow-rooted herbs (Heteropappus altaicus and Allium tanguticum) predominantly used water from the shallow soil layer (0–10 cm) over the entire growing seasons regardless of soil water availability. Overall, the contrasting water use patterns by coexisting plants demonstrate their adaptations to the fluctuations of soil moisture pulses in water-limited ecosystems.

Plant water use patterns reflect the complex interactions between different functional types and environmental conditions in water-limited ecosystems. However, the mechanisms underlying the water use patterns of plants in the alpine desert of the Qinghai–Tibet Plateau remain poorly understood. This study investigated seasonal variations in the water sources of herbs ( Carex moorcroftii , Astragalus adsurgens ) and shrubs ( Artemisia oxycephala , Hippophae rhamnoides ) using stable oxygen-18 isotope methods. The results indicated that the native herbs ( C. moorcroftii , A. adsurgens ) and one of the shrubs ( A. oxycephala ) mainly relied on water from the shallow layer (0–30 cm) throughout the growing season, while the introduced shrub ( H. rhamnoides ) showed plasticity in switching between water from shallow and deep soil layers depending on soil water availability. All studied plants primarily depended on water from shallow soil layers early in the season. The differences of water use patterns between the introduced and native plants are closely linked with the range of active root zones when competing for water. Our findings will facilitate the mechanistic understanding of plant–soil–water relations in alpine desert ecosystems and provide information for screening introduced species for sand fixation.

Interactions between lakes and the atmosphere at high-altitudes are still poorly understood due to difficulty in accessibility of direct measurements. This is particularly true for the Qinghai–Tibet Plateau (QTP), where approximately 50% of the lakes in China are located. Continuous direct measurements of the water flux and surface energy budget were made over the largest high-altitude saline lake in China, Qinghai Lake on the northeastern QTP, using the eddy covariance (EC) method from 11 May, 2013 through 10 May, 2015. Results indicated that annual evaporation of Qinghai Lake was 832.5 mm for 2013/2014 and 823.6 mm for 2014/2015, respectively. The surface energy budget and evaporation showed a strong seasonal pattern, with peaks in the latent and sensible heat flux observed in autumn and early winter. There was a 2–3 month delay between the maximum net radiation and maximum latent and sensible heat fluxes. Intraseasonal and seasonal variations in latent and sensible heat flux were strongly affected by different air masses. Westerly cold and dry air masses increased evaporation while southeast moist air mass suppressed evaporation, suggesting that the lakes might serve as an 'air-conditioner' to modify the temporal heat and water flux in the QTP.

Shrub patch configuration is a long-term evolutionary response to several environmental drivers and an equilibrium state in species competition. However, the variance in configuration along the precipitation gradient and its association with climate, soil, and adjacent vegetation remains unclear. Our study aimed to assess the variation of shrub patch configuration along a climatic gradient and the factors that affect shrub patch configuration, on the Inner Mongolia Plateau of Northwest China. Results showed that climate, soil, and vegetation contributed to 72.9% of the variance in shrub patch configuration. Interestingly, interspace/shrub radius ratio showed a decreasing trend with increasing precipitation transect. Patch size was positively correlated with aboveground biomass of interspace grass. Shrubs generally aggregated in high patches with low density on coarse soil texture, and vice versa. Moreover, shrub patches tended to occupy a larger percentage of landscape with increasing rainfall. To our knowledge, our study provides the first quantification of the effects of climate, soil, and vegetation on shrub patch configuration along a precipitation gradient in Northwest China, and may contribute to a better understanding of the structure and functions of shrub ecosystems with a broader ecological application in arid and semiarid regions.

To study the serum leptin level and insulin resistance on sustained virological response (SVR) in patients with chronic hepatitis C and to evaluate whether serum leptin level and insulin resistance are independent risk factors.Forty chronic hepatitis C patients were treated with interferon (alpha-2a) 5 MU and ribavirin 1.0 g for 24 weeks. The fasting serum leptin, insulin, glucose, HCV RNA load, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were measured and the insulin resistance index (HOMA-IR: homeostasis model of assessment) and body mass index (BMI) were calculated. Statistical methods used were univariate analyses and multivariable regression analyses.Of the 40 patients, 23 patients (57.5%) had a sustained virological response and 17 patients (42.5%) had a non-sustained virological response. Patients with a sustained virological response had lower serum leptin, HOMA-IR and BMI. Their SVR was associated with age, HCV RNA loads, serum leptin level, and insulin resistance, when analyzed with univariate analyses. SVR was not associated with sex, ALT, or AST. With multivariable regression analyses, serum leptin level and insulin resistance were found to be independent prediction factors for SVR in chronic hepatitis C patients with antivirus treatment.Serum leptin level and insulin resistance were associated with SVR in chronic hepatitis C patients; they were independent prediction factors for SVR.

In this paper, wave dynamics processes occurring in pulse detonation devices are analyzed both numerically and experimentally, including the propagation of detonation fronts, the motion of rarefaction waves in gas exhausting phase and the diffraction of shock waves at thrust nozzles. Numerical results are also compared with experiments to confirm the observed wave phenomena. In order to estimate operation roles of pulse detonation engines more accurately, the initiation of the air/hydrogen mixture is also examined experimentally at certain conditions. Numerical analysis indicates that pulse detonation devices can be operated in a quite high frequency, the gas-filling phase occupies a longer time in one detonation cycle, and decreasing the length of detonation chambers for the higher operation frequency is possible, but has its limitation.Copyright © 2002 by ASME