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Stipa tenacissima Does not Affect the Foliar δ^(13)C and δ^(15)N of Introduced Shrub Seedlings in a Mediterranean Semi-arid Steppe

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Journal of Integrative Plant Biology 2006年第8期48卷 897-905页

作者： fernando t.maestre Susana Bautista Jordi Cortina Departamento de Ecologia Universidad de AlicanteApartado de correos 9903080 AlicanteSpain Department of Biology Duke UniversityPhytotron BuildingScience DriveBox 90340DurhamNorth Carolina 27708-0340USA Centro de Estudios Ambientales del Mediterraneo C/ Charles Darwin 1446980 PaternaSpain

Recent studies have shown that the tussock grass Stipa tenacissima L. facilitates the establishment of late-successional shrubs, in what constitutes the first documented case of facilitation of woody plants by grasses. With the aim of increasing our knowledge of this interaction, in the present study we investigated the effects of S. tenacissima on the foliar δ13C, δ15N, nitrogen concentration, and carbon ： nitrogen ratio of introduced seedlings of Pistacia lentiscus L., Quercus coccifera L., and Medicago arborea L. in a semi-arid Mediterranean steppe. Six months after planting, the values of δ13C ranged between -26.9‰ and -29.6‰, whereas those of δ15N ranged between -1.9‰ and 2.7‰. the foliar C ： N ratio ranged between 10.7 and 53.5, and the nitrogen concentration ranged between 1.0% and 4.4%. We found no significant effect of the microsite provided by S. tenacissima on these variables in any of the species evaluated. the values of δ13C were negatively correlated with predawn water potentials in M. arborea and were positively correlated with relative growth rate in Q. coccifera. the values of δ15N were positively correlated with the biomass allocation to roots in the latter species. the present results suggest that the modification of environmental conditions in the are surrounding S. tenacissima was not strong enough to modify the foliar isotopic and nitrogen concentration of shrubs during the early stages after planting.

关键词： facilitation Medicago arborea Pistacia lentiscus Quercus coccifera stable isotopes steppe Stipa tenacissima.

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Functional leaf and size traits determine the photosynthetic response of 10 dryland species to warming

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Journal of Plant Ecology 2016年第6期9卷 773-783页

作者： Enrique Valencia JoséL.Quero fernando t.maestre Departamento de Biología y Geología Física y Química InorgánicaEscuela Superior de Ciencias Experimentales y TecnologíaUniversidad Rey Juan CarlosC/Tulipán s/n28933 MóstolesSpain Departamento de Ingeniería Forestal Escuela Técnica Superior de Ingeniería Agronómica y de MontesUniversidad de Córdoba Campus de Rabanales CrtaN-IV km.396C.P.14071 CórdobaSpain

Aims Relatively few studies so far have assessed how ongoing global warming will affect the photosynthetic performance of dryland plant *** evaluated the effects of warming on the photosynthetic rates of 10 species with contrasting functional attributes,and whether their functional traits modulated photosynthetic responses to *** A common garden experiment was conducted over 2 years with distinct environmental conditions(drier *** year).the experiment was designed as a randomized block design with two treatments:warming(control vs.~2.9℃ temperature increase)and species(Agropyron cristatum,Festuca ovina,Lygeum spartum,Medicago sativa,Plantago lanceolata,Psoralea bituminosa,Sanguisorba minor,Hedysarum coronarium,Dorycnium pentaphyllum and Phlomis herba-venti).We linked functional traits measurements with temporal variations in photosynthetic responses to *** Findings In the drier year,warming increased photosynthetic rates at the beginning of the growing season,suggesting a modification in the growing period(earlier spring).In the wetter year,functional traits modulated photosynthetic responses to *** species with shorter leaves(***)had higher photosynthetic rates under warming compared to smaller species with larger leaves(***).Our results highlight the importance of(i)studying photosynthetic responses along different years and(ii)considering functional traits when evaluating photosynthetic responses to climate change,particularly in stressful environments such as drylands.

关键词： photosynthesis climate change Mediterranean functional traits open top chambers

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Nitrogen addition delays the emergence of an aridity-induced threshold for plant biomass

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National Science Review 2023年第11期10卷 148-159页

作者： Hailing Li César terrer Miguel Berdugo fernando t.maestre Zaichun Zhu Josep Pe?uelas Kailiang Yu Lin Luo Jie-Yu Gong Jian-Sheng Ye State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems College of EcologyLanzhou University Department of Civil and Environmental Engineering Massachusetts Institute of Technology Instituto Multidisciplinar para el Estudio del Medio“Ramón Margalef ”Universidad de Alicante Institut de Biologia Evolutiva(CSIC-UPF) Departamento de Ecología Universidad de Alicante School of Urban Planning and Design Peking University Shenzhen Graduate SchoolPeking University CSIC Global Ecology Unit CREAF-CSIC-UAB CREAF Cerdanyola del Vallès High Meadows Environmental Institute Princeton University

Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity, potentially causing land degradation and desertification. It is largely unknown,however, whether these thresholds can be altered by other key global change drivers known to affect the water-use efficiency and productivity of vegetation, such as elevated CO2and nitrogen(N). Using >5000 empirical measurements of plant biomass, we showed that crossing an aridity(1–precipitation/potential evapotranspiration) threshold of ～0.50, which marks the transition from dry sub-humid to semi-arid climates, led to abrupt declines in aboveground biomass(AGB) and progressive increases in root:shoot ratios, thus importantly affecting carbon stocks and their distribution. N addition significantly increased AGB and delayed the emergence of its aridity threshold from 0.49 to 0.55(P te sensing estimates of leaf area index with simulations from multiple models, we found that CO2enrichment did not alter the observed aridity threshold. By 2100, and under the RCP 8.5 scenario, we forecast a 0.3% net increase in the global land area exceeding the aridity threshold detected under a scenario that includes N deposition, in comparison to a 2.9% net increase if the N effect is not considered. Our study thus indicates that N addition could mitigate to a great extent the negative impact of increasing aridity on plant biomass in drylands. these findings are critical for improving forecasts of abrupt vegetation changes in response to ongoing global environmental change.

关键词： aboveground biomass root:shoot ratios elevated CO2 nitrogen fertilization ecosystem threshold

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Variation in the methods leads to variation in the interpretation of biodiversity-ecosystem multifunctionality relationships

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Journal of Plant Ecology 2020年第4期13卷 431-441页

作者： Xin Jing Case M.Prager Aimée t.Classen fernando t.maestre Jin-Sheng He Nathan J.Sanders Rubenstein School of Environment and Natural Resources University of VermontBurlingtonVT 05405USA Gund Institute for Environment University of VermontBurlingtonVT 05405USA Center for Macroecology Evolutionand ClimateNatural History Museum of DenmarkCopenhagenDenmark Departamento de Biología GeologíaFísica y Química InorgánicaEscuela Superior de Ciencias Experimentales y TecnologíaUniversidad Rey Juan CarlosMóstoles 28933Spain Departamento de Ecología and Instituto Multidisciplinar para el Estudio del Medio“Ramon Margalef” Universidad de AlicanteAlicanteSpain Department of Ecology College of Urban and Environmental SciencesPeking UniversityBeijingChina Environmental Program Rubenstein School of Environment and Natural ResourcesUniversity of VermontBurlingtonVT 05405USA Present address:Department of Earth and Environmental Sciences KU LeuvenCelestijnenlaan 200E3001 LeuvenBelgium

Aims Biodiversity is often positively related to the capacity of an ecosystem to provide multiple functions simultaneously(***).However,there is some controversy over whether biodiversity–multifunctionality relationships depend on the number of functions ***,investigators have documented contrasting findings that the effects of biodiversity on ecosystem multifunctionality do not change or increase with the number of ecosystem ***,we provide some clarity on this issue by examining the statistical underpinnings of different multifunctionality *** We used simulations and data from a variety of empirical studies conducted across spatial scales(from local to global)and biomes(temperate and alpine grasslands,forests and drylands).We revisited three methods to quantify multifunctionality including the averaging approach,summing approach and threshold-based *** Findings Biodiversity–multifunctionality relationships either did not change or increased as more functions were *** results were best explained by the statistical underpinnings of the averaging and summing multifunctionality ***,by averaging the individual ecosystem functions,the biodiversity–multifunctionality relationships equal the population mean of biodiversity-single function relationships,and thus will not change with the number of ***,by summing the individual ecosystem functions,the strength of biodiversity–multifunctionality relationships increases as the number of functions *** proposed a scaling standardization method by converting the averaging or summing metrics into a scaling metric,which would make comparisons among different biodiversity *** addition,we showed that the range-relevant standardization can be applied to the threshold-based approach by solving for the mathematical artefact of the approach(*** effects of biodiversity may artificially increase with

关键词： averaging approach biodiversity ecosystem multifunctionality multiple threshold approach plant species richness spatial scale

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Breaking the land degradation-poverty nexus in drylands

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Science Bulletin 2022年第24期67卷 2508-2512页

作者： Nan Lü Bojie Fu Mark Stafford-Smith fernando t.maestre Linhai Cheng State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China CSIRO Land&Water Canberra ACT 2601Australia Department of Ecology University of AlicanteCarretera de San Vicente del RaspeigAlicante 03690Spain Multidisciplinary Institute for Environment Studies“Ramon Margalef” University of AlicanteCarretera de San Vicente del RaspeigAlicante 03690Spain

Drylands cover approximately 41%of the global land surface and provide homes to more than two billion people. Collectively,drylands constitute the largest terrestrial biome on the planet,and despite their low productivity per land area compared to other ecosystems, they have a major impact on the ecological functioning and climate of our planet through carbon storage, albedo, dust production, and water cycling [1].

关键词： planet 土地退化 cycling

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干旱区主导全球植被生产力增加趋势

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Science Bulletin 2023年第2期68卷 224-232,M0004页

作者：王帅傅伯杰魏芳莉朴世龙 fernando t.maestre Lixin Wang Wenzhe Jiao 刘焱序李琰李长嘉赵文武 State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100871China Department of Ecology University of AlicanteCarretera de San Vicente del RaspeigAlicante 03690Spain Multidisciplinary Institute for Environment Studies“Ramon Margalef” University of AlicanteCarretera de San Vicente del RaspeigAlicante 03690Spain Department of Earth Sciences Indiana University-Purdue University IndianapolisIndianapolis IN 46202USA

旱区(drylands)是指年平均降雨量与潜在蒸散发之比小于0.65的区域,占全球陆地表面的42%,是最易受气候变化影响的地区之一.然而,目前关于旱区植被对气候变化的响应特征及其对全球变绿和陆地生态系统生产力变化的相对贡献仍不清楚.本研究... 详细信息

旱区(drylands)是指年平均降雨量与潜在蒸散发之比小于0.65的区域,占全球陆地表面的42%,是最易受气候变化影响的地区之一.然而,目前关于旱区植被对气候变化的响应特征及其对全球变绿和陆地生态系统生产力变化的相对贡献仍不清楚.本研究通过集成模型和遥感数据分析发现,旱区对全球变绿的贡献较小,仅占33%±15%,但却主导了全球植被生产力(GPP)增加趋势,贡献达65%±16%旱区植被光合利用效率升高是解释变绿与生产力增加不一致的主要原因.旱区光能利用率主要受土壤水分的影响,大气水汽压差作用不显著,而非旱区主要受大气水汽压差的影响,土壤水的作用有限.因此,需要强调使用不同的水分胁迫指标来预测不同区域植被生产力变化的重要性,这也有助于理解较长时间尺度上植被绿度与生产力之间的解耦关系.

关键词：光能利用率水汽压差气候变化影响植被生产力旱区潜在蒸散发相对贡献集成模型

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Recent leveling off of vegetation greenness and primary production reveals the increasing soil water limitations on the greening Earth

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Science Bulletin 2021年第14期66卷 1462-1471,M0004页

作者： Xiaoming Feng Bojie Fu Yuan Zhang Naiqing Pan Zhenzhong Zeng Hanqin tian Yihe Lyu Yongzhe Chen Philippe Ciais Yingping Wang Lu Zhang Lei Cheng fernando t.maestre Marcos Fernández-Martínez Jordi Sardans Josep Peñuelas State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China International Center for Climate and Global Change Research School of Forestry and Wildlife SciencesAuburn UniversityAuburnAL 36832USA School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Laboratoire des Sciences du Climat et de l’Environnement CEA CNRS UVSQGif-sur-Yvette 91191France Oceans and Atmosphere Commonwealth Scientific and Industrial Research OrganisationAspendaleVictoria 3195Australia South China Botanic Garden Chinese Academy of SciencesGuangzhou 510650China Land and Water Commonwealth Scientific and Industrial Research OrganisationBlack MountainCanberraACT 2601Australia School of Water Resources and Hydropower Engineering Wuhan UniversityWuhan 430072China Departamento de Ecología and Instituto Multidisciplinar para el Estudio del Medio“Ramon Margalef” Universidad de AlicanteAlicante 03690Spain Global Ecology Unit CREAF-CEAB-UAB Spanish National Research CouncilCerdanyola del VallèsCatalonia 08193Spain

Global vegetation photosynthesis and productivity have increased substantially since the 1980s,but this trend is heterogeneous in both time and ***,we categorize the secular trend in global vegetation greenness into sustained greening,sustained browning and *** found that by 2016,increased global vegetation greenness had begun to level off,with the area of browning increasing in the last decade,reaching 39.0 million km^(2)(35.9%of the world’s vegetated area).this area is larger than the area with sustained increasing growth(27.8 million km^(2),26.4%);thus,12.0%±3.1%(0.019±0.004 NDVI a^(-1))of the previous earlier increase has been offset since 2010(2010–2016,Ption also leveled off,following the trend in vegetation greenness in time and *** leveling off was caused by increasing soil water limitations due to the spatial expansion of drought,whose impact dominated over the impacts of temperature and solar *** response of global gross primary production to soil water limitation was not identified by land submodels within Earth system *** results provide empirical evidence that global vegetation greenness and primary production are offset by water stress and suggest that as global warming continues,land submodels may overestimate the world’s capacity to take up carbon with global vegetation greening.

关键词： Ensemble empirical mode decomposition Global carbon cycle Global vegetation primary productivity Leveling off of Earth greening Global warming Soil water limitation

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Slope reliability and back analysis of failure with geotechnical parameters estimated using Bayesian inference

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 628-643页

作者： Luis-fernando Contreras Edwin t.Brown the University of Queensland St Lucia Campus

A Bayesian approach is proposed for the inference of the geotechnical parameters used in slope *** methodology involves the construction of posterior probability distributions that combine prior information on the parameter values with typical data from laboratory tests and site investigations used in *** posterior distributions are often complex,multidimensional functions whose analysis requires the use of Markov chain Monte Carlo(MCMC)*** procedures are used to draw representative samples of the parameters investigated,providing information on their best estimate values,variability and *** paper describes the methodology to define the posterior distributions of the input parameters for slope design and the use of these results for evaluation of the reliability of a slope with the first order reliability method(FORM).the reliability analysis corresponds to a forward stability analysis of the slope where the factor of safety(FS)is calculated with a surrogate model from the more likely values of the input *** Bayesian model is also used to update the estimation of the input parameters based on the back analysis of slope *** this case,the condition FS?1 is treated as a data point that is compared with the model prediction of *** analysis requires a sufficient number of observations of failure to outbalance the effect of the initial input *** parameters are updated according to their uncertainty,which is determined by the amount of data supporting *** methodology is illustrated with an example of a rock slope characterised with a Hoek-Brown rock mass *** example is used to highlight the advantages of using Bayesian methods for the slope reliability analysis and to show the effects of data support on the results of the updating process from back analysis of failure.

关键词： Bayesian analysis Hoek-Brown criterion Slope reliability Back analysis of failure

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Bayesian data analysis to quantify the uncertainty of intact rock strength

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第1期10卷 11-31页

作者： Luis fernando Contreras Edwin t.Brown Marc Ruest the University of Queensland St Lucia CampusBrisbaneQLD 4072Australia Golder Associates Pty.Ltd. BrisbaneAustralia

One of the main difficulties in the geotechnical design process lies in dealing with uncertainty. Uncertainty is associated with natural variation of properties, and the imprecision and unpredictability caused by insufficient information on parameters or models. Probabilistic methods are normally used to quantify uncertainty. However, the frequentist approach commonly used for this purpose has some ***, it lacks a formal framework for incorporating knowledge not represented by data. Second, it has limitations in providing a proper measure of the confidence of parameters inferred from data. the Bayesian approach offers a better framework for treating uncertainty in geotechnical design. the advantages of the Bayesian approach for uncertainty quantification are highlighted in this paper with the Bayesian regression analysis of laboratory test data to infer the intact rock strength parameters σand mused in the Hoek-Brown strength criterion. two case examples are used to illustrate different aspects of the Bayesian methodology and to contrast the approach with a frequentist approach represented by the nonlinear least squares(NLLS) method. the paper discusses the use of a Student’s t-distribution versus a normal distribution to handle outliers, the consideration of absolute versus relative residuals, and the comparison of quality of fitting results based on standard errors and Bayes factors. Uncertainty quantification with confidence and prediction intervals of the frequentist approach is compared with that based on scatter plots and bands of fitted envelopes of the Bayesian approach. Finally, the Bayesian method is extended to consider two improvements of the fitting analysis. the first is the case in which the Hoek-Brown parameter, a, is treated as a variable to improve the fitting in the triaxial region. the second is the incorporation of the uncertainty in the estimation of the direct tensile strength from Brazilian test results within the overall evaluati

关键词： Uncertainty Intact rock strength Bayesian analysis Hoek-Brown criterion

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transport mechanism in chemically reactive hybrid nanofluid flow containing gyrotactic micro-organisms over a curved oscillatory surface

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 177-192页

作者： M.NAVEED M.IMRAN t.ASGHAR Z.ABBAS Department of Mathematics Division of Science and TechnologyUniversity of Education Department of Mathematics The Islamia University of Bahawalpur

this paper examines the transport analysis, including both heat transfer and mass transfer, in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface. the influence of magnetic fields is also inspected in terms of their physical characteristics. to depict the phenomena of transport, modified versions of both Fick's and Fourier's laws are used. Additionally, the characteristics of both heterogeneous and homogeneous chemical reactions are also incorporated. Utilizing a curvilinear coordinate system, the flow problem is formulated as partial differential equations(PDEs)for momentum, concentration, microorganism field, and energy. An analytical solution to the obtained flow equations is achieved utilizing the homotopy analysis method(HAM).the effects of significant flow parameters on the pressure and microorganism fields, velocity, oscillation velocity, concentration, and temperature distributions are shown via graphs. Furthermore, the variations in skin friction, mass transfer rate, heat transfer rate, and local motile number due to different involved parameters are presented in tables and are analyzed in detail. Graphical results indicate that the curves of velocity and temperature fields are enhanced as the values of the solid volume fraction variables *** is also verified that the concentration rate field decreases as the values of the homogeneous reaction strength parameter and the radius of curvature parameter increase, and it increases with the Schmidt number and the heterogeneous reaction strength *** outcomes show a favorable response of the motile number to advanced values of the Peclet number, the Schmidt number, the microorganism difference parameter, and the bio-convective Lewis number.

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