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Spatial pattern of plant species diversity and the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China

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Journal of Arid Land 2017年第3期9卷 379-393页

作者： ZHANG Pingping SHAO Ming'an ZHANG Xingchang Institute of soil and Water Conservation Northwest A&F University state key laboratory of soil erosion and dryland farming on the loess plateau Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water Resources key laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

Understanding the spatial pattern of plant species diversity and the influencing factors has important implications for the conservation and management of ecosystem biodiversity. The transitional zone between biomes in desert ecosystems, however, has received little attention in that regard. In this study, we conducted a quantitative field survey （including 187 sampling plots） in a 40-km2 study area to determine the spatial pattern of plant species diversity and analyze the influencing factors in a Gobi Desert within the Heihe River Basin, Northwest China. A total of 42 plant species belonging to 16 families and 39 genera were recorded. Shrub and semi-shrub species generally represented the major part of the plant communities （covering 90% of the land surface）, while annual and perennial herbaceous species occupied a large proportion of the total recorded species （71%）. Patrick richness index （R）, Shannon-Wiener diversity index （H）, Simpson＇s dominance index （D）, and Pielou＇s evenness index （I） were all moderately spadaUy variable, and the variability increased with increasing sampling area. The semivariograms for R and H＇ were best fitted with Gaussian models while the semivariograms for D andJ were best fitted with exponential models. Nugget-to-still ratios indicated a moderate spatial autocorrelation for R, H＇, and D while a strong spatial autocorrelation was observed for J. The spatial patterns of R and H＇ were closely related to the geographic location within the study area, with lower values near the oasis and higher values near the mountains. However, there was an opposite trend for D. R, H＇, and D were significantly correlated with elevation, soil texture, bulk density, saturated hydraulic conductivity, and total porosity （P〈0.05）. Generally speaking, locations at higher elevations tended to have higher species richness and diversity and the higher elevations were characterized by higher values in sand and gravel contents, bulk density, and saturated hydraul

关键词： species diversity spatial heterogeneity environmental factors Gobi Desert transitional zone

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Spatiotemporal patterns of non-point source nitrogen loss in an agricultural catchment

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Water Science and Engineering 2016年第2期9卷 125-133页

作者： Jian-feng Xu Wei Yin Lei Ai Xiao-kang Xin Zhi-hua Shi College of Resources and Environment Huazhong Agricultural University Wuhan 430070 China Changjiang Water Resources Protection Institute Wuhan 430051 China state key laboratory of soil erosion and dryland farming on the loess plateau Institute of Soil and Water ConservationChinese Academy of Sciences Yangling 712100 China

Non-point source nitrogen loss poses a risk to sustainable aquatic ecosystems. However, non-point sources, as well as impaired river segments with high nitrogen concentrations, are difficult to monitor and regulate because of their diffusive nature, budget constraints, and resource deficiencies. For the purpose of catchment management, the Bayesian maximum entropy approach and spatial regression models have been used to explore the spatiotemporal patterns of non-point source nitrogen loss. In this study, a total of 18 sampling sites were selected along the river network in the Hujiashan Catchment. Over the time period of 2008e2012, water samples were collected 116 times at each site and analyzed for non-point source nitrogen loss. The morphometric variables and soil drainage of different land cover types were studied and considered potential factors affecting nitrogen loss. The results revealed that, compared with the approach using the Euclidean distance, the Bayesian maximum entropy approach using the river distance led to an appreciable 10.1% reduction in the estimation error, and more than 53.3% and 44.7% of the river network in the dry and wet seasons, respectively, had a probability of non-point source nitrogen impairment. The proportion of the impaired river segments exhibited an overall decreasing trend in the study catchment from 2008 to 2012, and the reduction in the wet seasons was greater than that in the dry seasons. High nitrogen concentrations were primarily found in the downstream reaches and river segments close to the residential lands. Croplands and residential lands were the dominant factors affecting non-point source nitrogen loss, and explained up to 70.7%of total nitrogen in the dry seasons and 54.7% in the wet seasons. A thorough understanding of the location of impaired river segments and the dominant factors affecting total nitrogen concentration would have considerable importance for catchment management.

关键词： Non-point source nitrogen Bayesian maximum entropy River distance Spatial regression Spatiotemporal pattern

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Changes in diversity,composition and assembly processes of soil microbial communities during Robinia pseudoacacia *** on the loess plateau,China

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Journal of Arid Land 2022年第5期14卷 561-575页

作者： WANG Kun WANG Xiaoxia FEI Hongyan WAN Chuanyu HAN Fengpeng state key laboratory of soil erosion and dryland farming on the loess plateau College of Natural Resources and EnvironmentNorthwest A&F UniversityYangling 712100China Research Center on soil&Water Conservation Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China

Robinia pseudoacacia L.(RP)restoration has increased vegetation cover in semi-arid regions on the loess plateau of China,but ecological problems have also occurred due to RP restoration,such as reduced soil ***,it is still uncertain how microbial diversity,composition and assembly processes change with RP restoration in semi-arid ***,amplicon sequencing of small subunit ribosomal ribonucleic acid(16S rRNA)and internal transcribed spacer(ITS)genes was performed to study soil bacterial and fungal diversity,composition and assembly processes at four study sites with different stand ages of RP plantations(Y10,RP plantation with stand ages less than 10 a;Y15,RP plantation with stand ages approximately 15 a;Y25,RP plantation with stand ages approximately 25 a;and Y40,RP plantation with stand ages approximately 40 a)along a 40-a chronosequence on the loess *** diversity of soil bacteria and fungi increased significantly during the restoration period from 10 to 15 a(Psoil bacterial communities were mainly related to changes in soil total nitrogen,nitrate nitrogen and moisture contents,while soil fungal communities were mainly shaped by soil organic carbon and nitrate nitrogen *** communities were structured by the heterogeneous selection and stochastic process,while fungal communities were structured primarily by the stochastic *** RP restoration induced an increase in the relative importance of heterogeneous selection on bacterial ***,this study reveals t

关键词： Robinia pseudoacacia microbial diversity community structure community assembly restoration semi-arid regions

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Effects of physical crust on soil detachment by overland flow in the loess plateau region of China

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International soil and Water Conservation Research 2024年第1期12卷 107-120页

作者： Jiaxin Liu Liding Chen Bing Wang Xiaoyu Peng School of Ecology and Environmental Science Yunnan UniversityKunming650091China state key laboratory of soil erosion and dryland farming on the loess plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYanglingShaanxi712100China University of Chinese Academy of Sciences Beijing100049China

Physical soil crust(PSC),a key component of surface soil structure,exists extensively in loess *** is considered to have a significant effect on soil detachment ***,the long-term effects and the corresponding mechanisms of PSC on soil detachment by overland flow are still not well understood,especially in natural *** investigate temporal variation in soil erosion resistance and the underlying factors during PSC formation,an 8×8-m soil plot was exposed to natural conditions in the loess plateau over a 524-day period spanning two rainy seasons and a winter between them.A flume test was conducted to determine soil detachment capacity(Dc)under six designed flow shear stress levels(5.66-22.11 Pa)using crusted(SC)and non-crusted(NSC)soil samples at different PSC development ***,two soil erosion resistance parameters,rill erodibility(K_(r))and critical shear stress(τ_(c)),were *** time,in the SC and NSC treatments,K_(r)decreased from 0.516 to 0.120 s m^(-1)and 0.521 to 0.223 s m^(-1),respectively,whileτ_(c)increased from 0.49 to 4.42 Pa and 0.26-2.46 Pa,*** in soil erosion resistance was rapid in the first one to two months,and then slowed down,with slight fluctuations *** the SC treatment,K_(r)was 42%lower andτ_(c)was 67%greater than those in the NSC *** properties changed greatly for both *** increased from 0 to 7.09 mm in the SC *** increased from 2.91 to 9.04 kPa and 3.01-4.78 kPa in SC and NSC treatments,*** soil erosion resistance parameters could be well predicted by SCT and Coh in the SC treatment(R^(2)≥0.82),while their best predictor was Coh in the NSC treatment(R^(2)≥0.90).The results demonstrate that PSC formation enhances soil erosion resistance in the soil detachment process in the loess region under natural *** study revealed the important role and complexity of PSC in the process of soil erosion,and provided theor

关键词： Physical soil crust formation soil heterogeneity Rill erodibility Critical shear stress

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Effects of water and nitrogen on growth and relative competitive ability of introduced versus native C_(4)grass species in the semi-arid loess plateau of China

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Journal of Arid Land 2021年第7期13卷 730-743页

作者： DING Wenli XU Weizhou GAO Zhijuan XU Bingcheng state key laboratory of soil erosion and dryland farming on the loess plateau Northwest A&F UniversityYangling 712100China College of Life Science Yulin UniversityYulin 719000China Institute of soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China

Switchgrass is an introduced C_(4)grass in the semi-arid loess plateau of China,but there is a lack of information to assess its ecological invasive *** this study,Old World bluestems(native C_(4)grass)and switchgrass were sowed at five mixture ratios(8:0,6:2,4:4,2:6 and 0:8)under two soil water levels(80%field capacity(FC)and 40%FC)and two nitrogen(N)treatments(0 and 100 mg N/kg dry soil,termed N0-unfertilized and N1-fertilized treatments,respectively)in a pot experiment in ***,root morphological traits and relative competitive abilities of these two species were *** showed that biomass of both species was significantly greater under 80%FC or N fertilization,and switchgrass had a relatively larger root:shoot ratio(RSR).Total root length(TRL)and root surface area(RSA)of switchgrass were significantly higher under 80%FC irrespective of N treatment,while those of Old World bluestems were only significantly higher under N fertilization.N had no significant effect on TRL and RSA of switchgrass,while RSA of Old World bluestems significantly increased under 80%FC and N *** 40%FC and N0-unfertilized treatment,the aggressivity of Old World bluestems was larger than zero at 2:6 and 4:4 mixture ratios of two species,whereas it was close to zero at 6:2 mixture *** competitive ability of switchgrass significantly increased under 80%FC or N *** aggressivity of Old World bluestems was negative at 6:2 mixture ratio under 80%FC and N fertilization,while it was positive at 2:6 mixture *** may become more aggressive when N deposition or rainfall increases,while a proper mixture ratio with appropriate water and N management could help with grassland management in the semi-arid loess plateau.

关键词： aggressivity nitrogen deposition relative competitive ability root trait water stress

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N and P resorption as functions of the needle age class in two conifer trees

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Journal of Plant Ecology 2018年第5期11卷 780-788页

作者： Zhiyou Yuan Xinrong Shi Feng Jiao Fengpeng Han state key laboratory of soil erosion and dryland farming on the loess plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYanglingShaanxi 712100China Institute of soil and Water Conservation Chinese Academy of Science and Ministry of Water ResourceYanglingShaanxi 712100China

Aims Given the importance of resorption in nutrient conservations,nu-trient resorption should change with leaf age if resorption depends on nutrient content,and if nutrient content changes with leaf ***,no study has addressed this *** Here,we measured N and P concentrations of needles of different ages in two woody evergreen conifer species-white spruce(Picea glauca Voss.)and balsam fir(Abies balsamea Mill.)-to determine the effects of needle aging on nutrient *** Findings For both species,N and P concentrations were higher in newer needles than in older *** resorption efficiency,*** of nutrients resorbed during senescence,also declined significantly with needle age from 73 to 22%in these two evergreen conifer *** difference in nutrient resorp-tion between old and young needles may be attributed to the size of N and P sink tissues,which is likely to decrease with needle *** results suggest that needle age affects the extent of N and P resorption in these two evergreen conifer species.

关键词： evergreen conifer needle age nutrient resorption Picea glauca Abies balsamea

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Study on the facilities and procedures for meltwater erosion of thawed soil

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International soil and Water Conservation Research 2016年第2期4卷 142-147页

作者： Yunyun Ban Tingwu Lei Chao Chen Zhiqiang Liu China Agricultural University Beijing 100083PR China state key laboratory of soil erosion and dryland farming on the loess plateau Institute of Soil and Water ConservationCAS and MWRYangling 712100PR China

High erosion rate of seasonal thawed soils by snow-and ice-melting runoff in the high altitude and latitude cold regions has great impacts on ecological systems,industries,agriculture and various manmade infrastructures as well as people's *** facilities and procedures are of great importance for the studies on simulating erosion processes of melt-frozen *** study focuses on the method and facility for simulating the thawing process of frozen *** facility includes soil freezing system,meltwater supply system and experimental flume system for thawed soil *** soil freezing system provides enough space to freeze soil columns in *** water supply system deliveries snow-or icemelting water flow of constant-rate at 0℃.The soil flumes of 200 or 300 cm long,10 cm wide and 12 cm high are designed to be assemble and convenient for soil freezing before they are thawed in one-dimensional manner from top to *** one-dimensional thawing process is realized as *** frozen soil flume is put on ice boxes and thermally insulated with heat-insulating materials all around to prevent frozen soil from being thawed from sidewalls and *** soil thaws with this system shows that it can meet the requirements of simulating the process of soil thawing from top to *** thawed soil flumes are connected from end to end to form rills of 6–8 m long to run the erosion experiments under different designed hydraulic *** equipment provides facility,method and operation process for simulating one-dimensional soil thawing to serve research on the effect of thawed soil depth on erosion process.

关键词： Melt-frozen soil erosion Method Facilities Procedures

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Changes in fine root biomass of Picea abies forests:predicting the potential impacts of climate change

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Journal of Plant Ecology 2018年第4期11卷 595-603页

作者： Z.Y.Yuan X.R.Shi F.Jiao F.P.Han state key laboratory of soil erosion and dryland farming on the loess plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYanglingShaanxi 712100China Institute of soil and Water Conservation Chinese Academy of Science and Ministry of Water ResourceYanglingShaanxi 712100China

Aims the impact of global warming on belowground processes,espe-cially on fine root production,is poorly understood in comparison with its aboveground *** Here,we compiled 227 measurements to assess the influence of temperature and precipitation on fine root biomass of Norway spruce(Picea abies[L.]Karst)forest ecosystems in the Eurasia boreal *** Findings We found that fine root biomass decreased significantly with *** was a biomass increase of 0.63 Mg ha−1 and 0.32 Mg ha−1 for fine roots<2 and<1 mm in diameter,respectively,with 1°C increase of mean annual *** was an increase of 0.5 and 0.1 Mg ha−1 per 100 mm year−1 precipitation for the two size classes of fine *** the adaption of root production can match the pace of global warming and water is not a limiting factor for plant growth,fine root biomass would be expected to increase by 40-140%in response to the predicted increase in tem-perature(3-10°C)over the next *** analyses highlighted the strongly positive influences of temperature and precipitation on belowground function,suggesting that predicted future climate change could substantially enhance belowground biomass in the boreal region where the greatest warming is *** potential increase of belowground biomass,coupled with aboveground biomass,may provide a better understanding of climate-ecosystem feedbacks.

关键词： boreal forest carbon climate change fine roots latitudinal gradient mean annual temperature and precipitation Norway spruce Picea abies production and biomass

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Effect of shrub-grass vegetation coverage and slope gradient on runoff and sediment yield under simulated rainfall

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International Journal of Sediment Research 2021年第1期36卷 29-37页

作者： Dandan Han Jingcheng Deng Chaojun Gu Xingmin Mu Peng Gao Jianjian Gao state key laboratory of soil erosion and dryland Agriculture on loess plateau Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources University of Chinese Academy of Sciences state key laboratory of soil erosion and dryland Agriculture on loess plateau Northwest A&F University Yangtze River Basin Monitoring Center Station for soil and Water Conservation Changjiang Water Resources Commission Suide Test Station of Water and soil Conservation Yellow River Conservancy Committee of the Ministry of Water Resources

Evaluating the benefits of sediment and runoff reduction in different vegetation types is essential for studying the mechanisms of soil and water conservation on the loess *** experiment was conducted in shrub-grass plots with nine levels of mixed vegetation coverage from 0% to 70%,three slopes(10°,15°,and 20°) and two rainfall intensities(1.0 and 2.5 mm/min).The results showed that the vegetation coverage and slope gradient significantly affect runoff and sediment ***-grass vegetation coverage had a significant effect on the runoff start-time,runoff flow velocity,runoff rate,and soil erosion rate on *** vegetation coverage could effectively delay the runoff starttime and decrease the runoff flow ***,the effects of the slope gradient on runoff and sediment yield are opposite to those of vegetation ***-grass vegetation coverage could effectively increase runoff and sediment yield reduction benefits,while their benefits were affected by the rainfall *** the 1.0 mm/min rainfall intensity,the reduction in the sediment production rate was greater than that under the 2.5 mm/min ***,when the shrub-grass vegetation coverage exceeded 42%,the runoff reduction benefit was more obvious at higher rainfall *** cumulative sediment yield increased with increasing cumulative runoff,and the rate of increase in the cumulative runoff was greater than that of the cumulative sediment yield with increasing of shrub-grass vegetation ***,there was a power function relationship between cumulative sediment yield and cumulative runoff yield(P loess plateau.

关键词： Simulated rainfall Shrub-grass coverage Slope Runoff and sediment yield

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Changes in soil free-living diazotrophic community and co-occurrence patterns along desert wetland degradation gradient in the Mu Us Desert,northern China

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Pedosphere 2023年第4期33卷 638-648页

作者： Kun WANG Hongyan FEI Qian TONG Chuanyu WAN Ruopeng PAN Fengpeng HAN state key laboratory of soil erosion and dryland farming on the loess plateau College of Natural Resources and EnvironmentNorthwest A&F UniversityShaanxi 712100(China) Research Center on soil&Water Conservation Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourcesShaanxi 712100(China)

Climate change and human activity have led to the degradation of desert ***-living diazotrophs are vital for soil nitrogen ***,a comprehensive understanding of how soil free-living diazotrophic communities and their co-occurrence patterns respond to desert wetland degradation is ***,quantitative polymerase chain reaction(qPCR),amplicon sequencing targeting nitrogenase gene(nifH),and network analysis were used to investigate the abundance,diversity,community composition,and co-occurrence patterns of soil free-living diazotrophs along the wetland degradation gradient,i.e.,non-degraded(ND),lightly degraded(LD),moderately degraded(MD),and severely degraded(SD),in the southeastern Mu Us Desert,northern *** abundance and Shannon,Simpson,Chao 1,and ACE indexes decreased(P0.05)was observed between ND and LD *** relative abundance of Proteobacteria generally decreased(by 53.5%–19.7%)across the different degradation levels,while the relative abundance of Cyanobacteria increased(by 6.2%–40.1%)from ND to MD *** abundance,diversity,and community composition of diazotrophs were most strongly related to soil organic carbon,followed by total nitrogen,moisture,and *** least number of network nodes and edges and the lowest density were observed for MD and SD wetlands,indicating that the complexity of free-living diazotrophic networks was reduced by continued ***,severe desert wetland degradation affected the abundance,diversity,and network complexity of soil free-living diazotrophs more negatively than light *** degradation promoted the growth of autotrophic diazotrophs and inhibited the growth of heterotrophic *** changes were mostly related to the loss of soil organic carbon.

关键词： amplicon sequencing biological nitrogen fixation co-occurrence network analysis nifH gene quantitative polymerase chain reaction soil organic carbon

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