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Effects of plant coverage on shrub fertile islands in the Upper Minjiang River Valley

Science China(Life Sciences) 2018年第3期61卷 340-347页

作者： Laiye Qu Zhongbin Wang Yuanyuan Huang Yuxin Zhang Chengjun Song Keming Ma State Key Laboratory of Urban and regional Ecology Research Center for Eco-environmental Science Chinese Academy of SciencesBeijing 100085 China University of Chinese Academy of Sciences Beijing 100049 China Department of Microbiology and Plant Biology University of Oklahoma Norman 73019 USA Institute of Energy and Environmental Protection Chinese Academy of Agriculture Engineering Beijing 100125 China

The patchy distribution of vegetation in dry land results in well-documented "fertile islands". However, the response of shrub fertile islands to plant recovery and the underlying mechanisms, such as the linkage plant and soil properties, remain *** sampled soils from areas with three different plant coverages(25%, 45%, and 75%) and three of their adjacent inter-plants to investigate soil physicochemical and microbial properties in the upper Minjiang River arid valley. The results showed that these factors were influenced by the persistence of plants that contrasted with the inter-plant interspaces. We found fertile islands in under-plant soil that were enhanced with increasing plant coverage, from 25% to 45% and 75%; however, there were no significant differences between 45% and 75% plant coverage apart from the soil clay content and the fungi to bacteria ratio. The soil microbial communities in under-plant soil were strongly influenced by the total soil carbon(TC), soil organic carbon(SOC),and available nitrogen(AN), whereas the microbial communities in inter-plant soil were primarily constrained by the AN and available phosphorous(AP). Moreover, the inter-plant soil properties, including gravimetric soil water content, pH, electrical conductivity(EC), and soil C:N ratio, were also strongly influenced by adjacent vegetation, which suggested that fertile islands may be beneficial for plant recovery in this region.

关键词： fertile islands plant coverage plant recovery semi-arid region

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Hydrological response to land use and land cover changes in a sub-watershed of West Liaohe River Basin,China

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Journal of arid Land 2014年第6期6卷 678-689页

作者： XiaoLi YANG LiLiang REN Yi LIU DongLai JIAO ShanHu JIANG State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Geographic and Biologic Information Nanjing University of Posts and Telecommunications

In recent years, the streamflow of the Laohahe Basin in China showed a dramatic decrease during the rainy season as a result of climate change and/or human activities. The objective of this work was to document significant streamflow changes caused by land use and land cover （LULC） changes and to quantify the impacts of the observed changes in Laohahe Basin. in the study area, the observed streamflow has been influenced by LULC changes, dams, and irrigation from rivers, industry, livestock and human consumption. Most importantly, the growth of population and gross domestic product （GDP） accompanied by the growth in industrial and agricultural activities, which led to LULC changes with increased residential land and cropland and decreased grassland since 2000s. Statistical methods and Variable Infiltration Capacity （VIC） hydrological model were used to estimate the effects of climate change and LULC changes on streamflow and evaportranspiration lET）. First, the streamflow data of the study area were divided into three sub-periods according to the Pettitt test. The hydrological process was then simulated by VIC model from 1964 to 2009. Furthermore, we compared the simulated results based on land use scenarios in 1989, 1999 and 2007, respectively for exploring the effect of LULC changes on the spatio-temporal distribution of streamflow and ET in the Laohahe Basin. The results suggest that, accompanied with climate change, the LULC changes and human water consumption appeared to be the most likely factors contributing to the sig- nificant reduction in streamflow in the Laohahe Basin by 64% from1999 to 2009.

关键词： hydrological response land use and land cover changes streamflow evapotranspiration semi-arid region

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Mapping Soil Texture Based on Field Soil Moisture Observations at a High Temporal Resolution in an Oasis Agricultural Area

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Pedosphere 2016年第5期26卷 699-708页

作者： YANG Renmin LIU Feng ZHANG Ganlin ZHAO Yuguo LI Decheng YANG Jinling YANG Fei YANG Fan State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) University of Chinese Academy of Sciences Beijing 100049(China)

Due to the almost homogeneous topography in low relief areas, it is usually difficult to make accurate predictions of soil properties using topographic covariates. In this study, we examined how time series of field soil moisture observations can be used to estimate soil texture in an oasis agricultural area with low relief in the semi-arid region of northwest China. Time series of field-observed soil moisture variations were recorded for 132 h beginning at the end of an irrigation event during which the surface soil was *** correlation between two time-adjacent soil moisture conditions was used to select the factors for fuzzy c-means clustering. In each of the ten generated clusters, soil texture of the soil sample with the maximum fuzzy membership value was taken as the cluster centroid. Finally, a linearly weighted average was used to predict soil texture from the centroids. The results showed that soil moisture increased with the increase of clay and silt contents, but decreased with the increase of sand content. The spatial patterns of soil moisture changed during the entire soil drying phase. We assumed that these changes were mainly caused by spatial heterogeneity of soil texture. A total of 64 independent samples were used to evaluate the prediction accuracy. The root mean square error(RMSE)values of clay, silt and sand were 1.63, 2.81 and 3.71, respectively. The mean relative error(RE) values were 9.57% for clay, 3.77% for silt and 12.83% for sand. It could be concluded that the method used in this study was effective for soil texture mapping in the low-relief oasis agricultural area and could be applicable in other similar irrigation agricultural areas.

关键词： digital soil mapping fuzzy c-means clustering low relief particle-size distribution semi-arid region water content

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Response of forestland soil water content to heavy rainfall on Beijing Mountain, northern China

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Journal of Forestry Research 2016年第3期27卷 541-550页

作者： Jianbo Jia Xinxiao Yu Yitao Li College of Soil and Water Conservation Beijing Forestry University Beijing 100083 People's Republic of China Shanxi Institute of Forest Inventory and Planning Taiyuan 030012 People's Republic of China

Continuous recording of precipitation and soil water content（SWC）, especially during long periods of torrential rainfall, has proven challenging. Over a 16 h period spanning 21-22 July, 2012, Beijing experienced historic rainfall that totaled 164.4 mm. We used large lysimeter technology in four forested plots to record precipitation and variation in SWC at 10-min intervals to quantify the response of forestland SWC to heavy rainfall in a semi-arid area. Mean,maximum and minimum rainfall intensities were 23.4, 46.8and 12.0 mm/h, respectively. Rainfall was concentrated in 2-6 mm bursts that accounted for 67.32 % of the total rainfall event. Soil moisture conditions in this region are strongly dependent on patterns of precipitation. Water infiltration into 20, 40, 60, 80, 100, 120 and 160 cm soil layers required 1, 5,20, 37, 46, 52 and 61 mm of precipitation, respectively, and to fully saturate these soil layers required 80, 120, 140, 150, 180,200 and 220 mm of precipitation, respectively.

关键词： semi-arid region Soil water content Soilwater deficit Lysimeter

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A field investigation of wind erosion in the farming–pastoral ecotone of northern China using a portable wind tunnel: a case study in Yanchi County

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Journal of arid Land 2018年第1期10卷 27-38页

作者： nan ling dong zhibao xiao weiqiang li chao xiao nan song shaopeng xiao fengjun du lingtong School of Geography and Tourism Shaanxi Normal UniversityXi'an 710119China Research Center for Westerm Development Ningxia UniversityYinchuan 750021China Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China Ningxia UniversityYinchuan 750021China

The farming-pastoral ecotone in northern China is an extremely fr@e ecological zone where wind erosion of cropland and rangeland is easy to occur. In this study, using a portable wind tunnel as a wind simulator, we conducted field simulated wind erosion experiments combined with laboratory analysis to investigate wind erosion of soils in trampled rangeland, non-tilled cropland and tilled cropland in Yanchi County, China. The results showed that compared with rangeland, the cropland had a higher soil water holding capacity and lower soil bulk density. The wind erosion rate of trampled rangeland was much higher than those of non-tilled cropland and tilled cropland. For cropland, the wind erosion rate of the soil after tilling was surprisingly less than that of the soil before tilling. With increasing of wind speed, the volume mean diameter of the eroded sediment collected by the trough in the wind tunnel generally increased while the clay and silt content decreased for all soils. The temporal variation in wind erosion of the trampled rangeland indicated that particle entrainment and dust emission decreased exponentially with erosion time through the successive wind erosion events due to the exhaustion of erodible particles.

关键词： wind erosion rate wind tunnel eroded sediment soil particle size cropland rangeland semi-arid region

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Evapotranspiration and soil water relationships in a range of disturbed and undisturbed ecosystems in the semi-arid Inner Mongolia,China

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Journal of Plant Ecology 2011年第1期4卷 49-60页

作者： Nan Lu Shiping Chen Burkhard Wilske Ge Sun Jiquan Chen Department of Environmental Sciences University of ToledoToledoOH 43606USA Research Center for Eco-Environmental Sciences Chinese Academy of Sciences18 Shuangqing RoadBeijing 100085China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyThe Chinese Academy of Sciences20 Xiangshan NanxincunBeijing 100093China USDA Forest Service Southern Research Station 920 Main CampusVenture II BuildingSuite 300RaleighNC 27606USA

Aims Evapotranspiration(ET)is a key component of water balance and is closely linked to ecosystem *** arid regions,large proportion of precipitation(PPT)is returned to the atmosphere through ET,with only a small amount available to *** objective was to examine the variability in ET–soil water relationship based on a set of ecosystems that are representative for semi-arid Inner Mongolia and its main land use *** This study used Eddy covariance(EC)data of water vapor(***,mm),PPT(mm),soil volumetric water content(VWC,%),root biomass density and soil properties from three paired sites in semi-arid Inner Mongolia:cropland(Cropland-D)versus undisturbed grassland(Steppe-D),grazed grassland(Grazed Steppe-X)versus fenced grassland(Fenced Steppe-X)and poplar plantation(Poplar-K)versus undisturbed shrubland(Shrubland-K).The paired sites experienced similar climate conditions and were equipped with the same monitoring *** Findings The ET/PPT ratio was significantly lower at Cropland-D and Grazed Steppe-X in comparison to the undisturbed grasslands,Steppe-D and Fenced *** differences are in part explained by the lower VWC in the upper soil layers associated with compaction of surface soil in heavily grazed and fallow *** contrast,the ET/PPT ratio was much higher at the poplar plantation compared to the undisturbed shrubland because poplar roots tap *** VWC of different soil layers responded differently to rainfall events across the six study *** for Poplar-K,ETwas significantly constrained by VWC at the other five sites,although the correlation coefficients varied among soil *** relative contribution of soil water to ET correlated with the density of root biomass in the soil(R2=0.67,P<0.01).The soil water storage in the upper 50 cm of soil contributed 59,43,64 and 23%of total water loss as ET at Steppe-D,Cropland-D,Shrubland-K and Poplar-K,*** across-site analysis indicate

关键词： evapotranspiration soil water storage land use Inner Mongolia semi-arid region eddy-flux measurements

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Gross nitrogen transformations and N2O emission sources in sandy loam and silt loam soils

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Journal of arid Land 2021年第5期13卷 487-499页

作者： LANG Man LI Ping WEI Wei Jiangsu Key Laboratory of Agricultural Meteorology Nanjing University of Information Science&TechnologyNanjing 210044China Department of Agricultural Resources and Environment Nanjing University of Information Science&TechnologyNanjing 210044China

The soil type is a key factor influencing N(nitrogen)cycling in soil;however,gross N transformations and N_(2)O emission sources are still poorly *** this study,a laboratory 15N tracing experiment was carried out at 60%WHC(water holding capacity)and 25℃to evaluate the gross N transformation rates and N_(2)O emission pathways in sandy loam and silt loam soils in a semi-arid region of Heilongjiang Province,*** results showed that the gross rates of N mineralization,immobilization,and nitrification were 3.60,1.90,and 5.63 mg N/(kg·d)in silt loam soil,respectively,which were 3.62,4.26,and 3.13 times those in sandy loam soil,*** ratios of the gross nitrification rate to the ammonium immobilization rate(n/ia)in sandy loam soil and silt loam soil were all higher than 1.00,whereas the n/ia in sandy loam soil(4.36)was significantly higher than that in silt loam soil(3.08).This result indicated that the ability of sandy loam soil to release and conserve the available N was relatively poor in comparison with silt loam soil,and the relatively strong nitrification rate compared to the immobilization rate may lead to N loss through NO_(3)–*** aerobic conditions,both nitrification and denitrification made contributions to N_(2)O *** was the dominant pathway leading to N_(2)O production in soils and was responsible for 82.0%of the total emitted N_(2)O in sandy loam soil,which was significantly higher than that in silt loam soil(71.7%).However,the average contribution of denitrification to total N_(2)O production in sandy loam soil was 17.9%,which was significantly lower than that in silt loam soil(28.3%).These results are valuable for developing reasonable fertilization management and proposing effective greenhouse gas mitigation strategies in different soil types in semiarid regions.

关键词： gross N transformation rates 15N tracing N2O emission sources sandy loam silt loam semi-arid region

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Effects of climate change and land-use changes on spatiotemporal distributions of blue water and green water in Ningxia, Northwest China

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Journal of arid Land 2021年第7期13卷 674-687页

作者： WU Jun DENG Guoning ZHOU Dongmei ZHU Xiaoyan MA Jing CEN Guozhang JIN Yinli ZHANG Jun College of Resources and Environmental Science Gansu Agricultural UniversityLanzhou 730070China Research Center for Water-saving Agriculture in Gansu Province Lanzhou 730070China Gansu Provincial Key Laboratory of arid Land Crop Science Gansu Agricultural UniversityLanzhou 730070China

Water resources are a crucial factor that determines the health of ecosystems and socio-economic development;however,they are under threat due to climate change and human *** quantitative assessment of water resources using the concept of blue water and green water can improve regional water resources *** this study,spatiotemporal distributions of blue water and green water were simulated and analyzed under scenarios of climate change and land-use changes using the Soil and Water Assessment Tool(SWAT)in Ningxia Hui Autonomous region,Northwest China,between 2009 and *** water,a leading component of water resources,accounted for more than 69.00%of the total water resources in *** water and green water showed a single peak trend on the monthly and annual scales during the study *** the spatial scale,the southern region of Ningxia showed higher blue water and green water resources than the northern *** spatiotemporal distribution features of blue water,green water,and green water flow had strong correlations with ***,the simulation identified the climate change in Ningxia to be more influential on blue water and green water than land-use *** study provides a specific scientific foundation to manage water resources in Ningxia when encountered with climate change together with human activities.

关键词： blue water green water climate change human activities SWAT semi-arid region

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Aboveground nutrient components of Eucalyptus camaldulensis and E. grandis in semiarid Brazil under the nature and the mycorrhizal inoculation conditions

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Journal of Forestry Research 2009年第1期20卷 15-22页

作者： Marcela C. Pagano Antonio F. Bellote Maria R. Scotti Microorganism-Plant Interaction LaboratolT Institute of Biological Sciences Federal University of Minas Gerais Av. Antonio Carlos 6627 Pampulha CEP： 31270-901 Belo Horizonte MG Brazil Embrapa Forestry Estrada da Ribeira km 111 Caixa Postal 319 - Colombo PR - 83411-000- Brazil.

A study was conducted to evaluate the aboveground biomass, nutrient content and the percentages of mycorrhizal colonization in Eucalyptus camaldulensis and Eucalyptus grand＆ plantations in the semiarid region （ 15° 09′ S 43° 49′ W） in the north of the State of Minas Gerais in Brazil. Results show that the total above-ground biomass （dry matter） was 33.6 ***^-1 for E. camaldulensis and 53.1 Mg·ha^-1 for E. grandis. The biomass of the stem wood, leaves, branches, and stein bark for E. camaldulens accounted for 64.4%, 19.6%, 15.4%, and 0.6% of the total biomass, respectively （Table 2）; meanwhile a similar partition of the total above-ground biomass was also found for E. grand＆. The dry matter of leaves and branches of E. camaldulensis accounted for 35% of total biomass, and the contents of N, P, K, Ca, Mg, and S in leaves and branches accounted for 15.5%, 0.7%, 12.3%, 22.6%, 1.9%, and 1.4% of those in total above-ground biomass, respectively. In the trunk （bark and wood）, nutrient accumulation in general was lower. Nutrient content of E. grand＆ presented little variation compared with that orE. camaJd^llensis. Wood localized in superior parts of trunk presented a higher concentration of P and bark contained significant amounts of nutrients, especially in E. grand＆. This indicated that leaving vegetal waste is of importance on the site in reducing the loss of tree productivity in this semi-arid region. The two species showed mycotrophy.

关键词： Eucalyptus biomass nutrient components semi-arid region mycorrhizal symbioses Brazil

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Quantification of groundwater recharge and evapotranspiration along a semi-arid wetland transect using diurnal water table fluctuations

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Journal of arid Land 2021年第5期13卷 455-469页

作者： JIA Wuhui YIN Lihe ZHANG Maosheng ZHANG Xinxin ZHANG Jun TANG Xiaoping DONG Jiaqiu School of Water Resources and Environment China University of Geosciences(Beijing)Beijing 100083China Xi'an Center of Geological Survey China Geological SurveyXi'an 710054China Institute of Disaster Prevention and Ecological Restoration Xi'an Jiaotong UniversityXi'an 710049China Chinese Academy of Geological Sciences Beijing 100037China

Groundwater is a vital water resource in arid and semi-arid *** groundwater table fluctuations are widely used to quantify rainfall recharge and groundwater evapotranspiration(ET_(g)).To assess groundwater resources for sustainable use,we estimated groundwater recharge and ET_(g) using the diurnal water table fluctuations at three sites along a section with different depths to water table(DWT)within a wetland of the Mukai Lake in the Ordos Plateau,Northwest *** water table level was monitored at an hourly resolution using a Keller DCX-22 A data logger that measured both the total pressure and barometric pressure,so that the effect of barometric pressure could be *** this study site,a rapid water table response to rainfall was observed in two shallow wells(i.e.,Obs1 and Obs2),at which diurnal water table fluctuations were also observed over the study period during rainless days,indicating that the main factors influencing water table variation are rainfall and ET_(g).However,at the deep-water table site(Obs3),the groundwater level only reacted to the heaviest rainfalls and showed no diurnal *** recharge and ET_(g) were quantified for the entire hydrological year(June 2017–June 2018)using the water table fluctuation method and the Loheide method,respectively,with depth-dependent specific *** results show that the total annual groundwater recharge was approximately 207 mm,accounting for 52%of rainfall at Obs1,while groundwater recharge was approximately 250 and 21 mm at Obs2 and Obs3,accounting for 63%and 5%of rainfall,*** addition,the rates of groundwater recharge were mainly determined by rainfall intensity and *** daily mean ET_(g) at Obs1 and Obs2 over the study period was 4.3 and 2.5 mm,respectively,and the main determining factors were DWT and net radiation.

关键词： groundwater recharge groundwater evapotranspiration water table fluctuation semi-arid region Ordos Plateau

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