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Evaluating soil acidification risk and its effects on biodiversity–ecosystem multifunctionality relationships in the drylands of China
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作者 Lan Du Shengchuan Tian +5 位作者 Nan Zhao Bin Zhang Xiaohan Mu Lisong Tang Xinjun Zheng Yan Li 《Forest Ecosystems》 SCIE CSCD 2024年第2期162-171,共10页
Background:Soil acidifcationn caused by anthropogenic activities may aft soil biochemical cydling,bidiversity,productivity,and multiple eosystem-related functions in drylands.However,to date,such information is lackin... Background:Soil acidifcationn caused by anthropogenic activities may aft soil biochemical cydling,bidiversity,productivity,and multiple eosystem-related functions in drylands.However,to date,such information is lacking to support this hypothesis.Methods Based on a transect survey of 78 naturally assembled shrub communities,we caloulated acid deposition flux in Northwest China and evaluated its likely ecological ffets by testing three altemnative hypotheses,namely:.nidche complementarity,mass ratio,and vegetation quantity hypotheses Rao's quadratic entopy and community-weighted mean traits were employed to represent the complementary aspect of niche complementarity and mass ratio effects,respectively.Resulbs:We observed that in the past four decades,the concentrations of exchangeable base cations in soil in Northwest China have decreased significantly to the extent of having faced the risk of depletion,whereas changes in the calium carbonate content and pH of soil were not significant.Adid deposition primani ly increased the aboweground biomass and shrub density in shrublands but had no sigmificant effect on shrub richness and ecasystem multifunctionality(EMF),indicating that acid deposition had positive but weak ecological effects on dryland ecosystems.Community wd ghted mean of functional traits(representing the mass ratio hypothesis)correlated negatively with EMF,whereas both Rao's quadratic entropy(representing the niche complementarity hypothesis)and aboveground biomass(representing the vegetation quantity hypothesis)correlated positively but insignifcantly with EMF.These biodiversity-EMF relationships highlight the fragility and instability of drylands relative to forest ecasystems.Concuions:The findings from this study serve as important reference points to understand the ris of soil acidification in arid regions and its impacts on biodiversity-EMF relationships. 展开更多
关键词 Soil acidification risk BIODIVERSITY Ecosystem multifunctionality Niche complementarity hypothesis mass ratio hypothesis Vegetation quantity hypothesis
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Evaluating alternative hypotheses behind biodiversity and multifunctionality relationships in the forests of Northeastern China 被引量:2
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作者 Qingmin Yue Minhui Hao +5 位作者 Yan Geng Xuerui Wang Klaus von Gadow Chunyu Zhang Xiuhai Zhao Lushuang Gao 《Forest Ecosystems》 SCIE CSCD 2022年第3期301-310,共10页
Background:The importance of biodiversity in maintaining multiple ecosystem functions has been widely accepted.However,the specific mechanisms affecting biodiversity and ecosystem multifunctionality(BEMF)relationships... Background:The importance of biodiversity in maintaining multiple ecosystem functions has been widely accepted.However,the specific mechanisms affecting biodiversity and ecosystem multifunctionality(BEMF)relationships in forests are largely unknown.This is particularly evident for the macroscale of a large forested landscape.Methods:Based on 412 one-tenth hectare field plots distributed over forested areas across northeastern China,we evaluated three alternative hypotheses explaining the relationships between BEMF,namely:niche complementarity,mass ratio,and vegetation quantity effect.We used Rao's quadratic entropy and community weighted mean trait values to quantify forest“biodiversity”.These two variables represent two complementary aspects of functional properties,which are in line with niche complementary and mass ratio effects,respectively.Results:Ecosystem multifunctionality was negatively associated with the community weighted mean values of acquisitive traits(a proxy of mass ratio effect).Rao's quadratic entropy(a proxy of niche complementarity)had no relationship with ecosystem multifunctionality.Higher stand biomass greatly increased ecosystem multifunctionality,which is in line with the vegetation quantity effect.Our results confirm that in the temperate forests of northeastern China,the relationship of BEMF was primarily affected by vegetation quantity,followed by mass ratio effects.Conclusions:The results of this study contribute to a better understanding of the main drivers of ecosystem multifunctionality in forest ecosystems.The results of this study provide additional evidence to support the vegetation quantity and mass ratio hypotheses in forest ecosystems. 展开更多
关键词 Biodiversity and ecosystem multifunctionality Biomass Functional traits mass ratio effect Niche complementarity effect Vegetation quantity effect
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采用质量差和超小导程/直径比丝杠传动的 点胶量精细计量技术及系统设计(英文)
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作者 顾立志 郭帅亮 +1 位作者 韩佳兴 钟琛 《华侨大学学报(自然科学版)》 北大核心 2017年第6期760-767,共8页
基于冗余技术原理,采用制件点胶前后质量差和超小导程/直径比阿基米德丝杠技术组合,辅以自润滑双导轨设计,保证点胶量控制胶滴为(0.200±0.001)g;采用模块化设计,实现点胶机性能的高精度和功能的适度柔性,并通过模块化试制模拟样机... 基于冗余技术原理,采用制件点胶前后质量差和超小导程/直径比阿基米德丝杠技术组合,辅以自润滑双导轨设计,保证点胶量控制胶滴为(0.200±0.001)g;采用模块化设计,实现点胶机性能的高精度和功能的适度柔性,并通过模块化试制模拟样机,优化点胶机的空间结构及整机可靠性.研究结果表明:该方案保证了点胶量的实时精密控制且同时满足生产节拍的要求. 展开更多
关键词 精细计量 点胶量 质量差 超小导程/直径比丝杠 冗余技术 线性误差
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用磁聚焦法测量真空磁导率
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作者 黄河 马静 刘竹琴 《信息技术》 2012年第5期52-54,共3页
用水平偏转板间电场给电子加速,使电子具有共同的平行于电场场强的速度;将示波管置于载流螺线管的匀强磁场里,电子在磁场中做圆周运动的周期与电子的速度无关,从而可以达到电子束聚焦的效果。利用电子在电场和磁场中受到洛伦兹力的作用... 用水平偏转板间电场给电子加速,使电子具有共同的平行于电场场强的速度;将示波管置于载流螺线管的匀强磁场里,电子在磁场中做圆周运动的周期与电子的速度无关,从而可以达到电子束聚焦的效果。利用电子在电场和磁场中受到洛伦兹力的作用和其轨迹的特点,以电子荷质比为已知量,从间接角度出发测量空气磁导率。 展开更多
关键词 真空磁导率 磁聚焦法 电子荷质比
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土壤水含量的表述及方程式 被引量:3
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作者 杨继民 郭柏寿 +2 位作者 潘学燕 成敏 杨继涛 《编辑学报》 CSSCI 北大核心 2012年第5期443-445,共3页
列举书刊中关于土壤水含量的表述及方程式,指出其表述及方程式的疏漏和错误之处。认为:土壤水含量以质量计的应称为土壤质量含水量或土壤水土质量比,采用量符号ξ;以体积计的应称为土壤体积含水量或土壤水体积分数,采用量符号φ。分别... 列举书刊中关于土壤水含量的表述及方程式,指出其表述及方程式的疏漏和错误之处。认为:土壤水含量以质量计的应称为土壤质量含水量或土壤水土质量比,采用量符号ξ;以体积计的应称为土壤体积含水量或土壤水体积分数,采用量符号φ。分别给出了规范的量方程式和数值方程式。 展开更多
关键词 土壤质量含水量 质量比 土壤体积含水量 体积分数 量方程式 数值方程式
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