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Biodiversity effects and transgressive overyielding 被引量:6
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作者 Bernhard Schmid Andy Hector +1 位作者 Prasenjit Saha Michel Loreau 《Journal of Plant Ecology》 SCIE 2008年第2期95-102,共8页
Aims The potential for mixtures of plant species to produce more biomass than every one of their constituent species in monoculture is still controversially discussed in the literature.Here we tested how this socalled... Aims The potential for mixtures of plant species to produce more biomass than every one of their constituent species in monoculture is still controversially discussed in the literature.Here we tested how this socalled transgressive overyielding is affected by variation between and within species in monoculture yields in biodiversity experiments.Methods We use basic statistical principles to calculate expected maximum monoculture yield in a species pool used for a biodiversity experiment.Using a real example we show how between-and withinspecies variance components in monoculture yields can be obtained.Combining the two components we estimate the importance of sampling bias in transgressive overyielding analysis.Important Findings The net biodiversity effect(difference between mixture and average monoculture yield)needed to achieve transgressive overyielding increases with the number of species in a mixture and with the variation between constituent species in monoculture yields.If there is no significant variation between species,transgressive overyielding should not be calculated using the best monoculture,because in this case the difference between this species and the other species could exclusively reflect a sampling bias.The sampling bias decreases with increasing variation between species.Tests for transgressive overyielding require replicated species’monocultures.However,it can be doubted whether such an emphasis on monocultures in biodiversity experiments is justified if an analysis of transgressive overyielding is not the major goal. 展开更多
关键词 biodiversity experiments mixtures MONOCULTURES overyielding analysis sampling bias
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施肥和刈割协同对藏北高原禾草混播群落动态和超产的影响
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作者 周娟娟 魏巍 《草业学报》 CSCD 北大核心 2023年第10期28-39,共12页
应用乡土物种构建人工草地是修复退化草地的有效措施。本研究以藏北高原驯化的垂穗披碱草、麦宾草和中亚早熟禾3种乡土草种为试验对象,设置单播(S_(1)~S_(3))和混播(M_(1)~M_(4))共7个播种组合为主区,嵌套施肥(fertilization,F)、刈割(c... 应用乡土物种构建人工草地是修复退化草地的有效措施。本研究以藏北高原驯化的垂穗披碱草、麦宾草和中亚早熟禾3种乡土草种为试验对象,设置单播(S_(1)~S_(3))和混播(M_(1)~M_(4))共7个播种组合为主区,嵌套施肥(fertilization,F)、刈割(cutting,C)、施肥+刈割(F+C),无施肥无刈割(Con)为副区。筛选最佳播种组合,明确不同禾草草地的群落消长动态,探究混播草地超产效应和多样性效应以及物种个体对施肥和刈割的响应,以期为藏北高原退化草地的生态恢复提供科学依据。结果表明:不同播种组合禾草草地均表现出明显的生长季种群消长动态,地上生物量均在9月20日(生长季末)达到峰值,垂穗披碱草为混播群落优势种群;8月20日(孕穗期)根系生物量积累达到极大值,混播M4中F处理根系生物量最高,为669.61 g·m^(-2);垂穗披碱草+麦宾草+中亚早熟禾3物种混播(M_(4))地上生物量最高,F和F+C处理显著增加群落的地上生物量,F+C处理地上生物量高达3190.83 g·m^(-2),垂穗披碱草+麦宾草+中亚早熟禾混播配套施肥和刈割措施是藏北高原建植人工草地较理想的方式。结合自然对数响应比值(LNRR)分析,3个物种中垂穗披碱草的竞争力最强,中亚早熟禾次之,麦宾草最弱。混播M_(1)、M_(2)、M_(3)(Con和C处理)和M4相对产量总和(RYT)皆大于1,且都存在超产;其中,混播M1中Con和C处理、M_(2)中C、F和F+C处理、M_(4)中Con和C处理的选择效应和互补效应共同主导超产效应,M_(1)中F和F+C处理、M_(2)中Con处理、M_(3)中Con和C处理的互补作用主导超产效应。 展开更多
关键词 人工草地 乡土物种 施肥和刈割 群落动态 超产效应 藏北高原
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植物群落物种多样性对生态系统生产力的影响 被引量:44
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作者 江小雷 张卫国 +1 位作者 严林 王刚 《草业学报》 CSCD 2004年第6期8-13,共6页
物种多样性对生态系统功能的影响是生态学领域所研究的核心科学问题之一。本研究利用人工构建的一年生植物群落,就植物群落物种多样性、植物功能群多样性和功能群成分对生态系统生产力的影响进行了研究,并对物种多样性-生态系统功能关... 物种多样性对生态系统功能的影响是生态学领域所研究的核心科学问题之一。本研究利用人工构建的一年生植物群落,就植物群落物种多样性、植物功能群多样性和功能群成分对生态系统生产力的影响进行了研究,并对物种多样性-生态系统功能关系的作用机制———取样效应和生态位互补效应进行了验证。结果表明,随着物种多样性的增加,群落生产力呈增加趋势,物种多样性对生态系统功能存在正效应,物种多样性增加的总体效应可通过生产力与物种数的二次函数关系y=-37.463x2+478.63x+1097.3,(R2=0.9167)得到较好的体现。功能群多样性和功能群成分均对系统功能有显著影响。总体而言,物种数一定时,功能群多样性较高的群落其生产力水平也较高,而功能群多样性一致时,含C3、C4功能成分的群落其生产力水平较其他群落的高。分析结果还表明,在多样性-生态系统功能关系中,取样效应和生态位互补效应共同发生作用,说明物种的特性及物种在资源利用方面表现出的异质性对生态系统功能可能都有重要影响。 展开更多
关键词 物种多样性 生态系统功能 生产力 取样效应 生态位互补效应 超产现象
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生产力、可靠度与物种多样性:微宇宙实验研究 被引量:26
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作者 张全国 张大勇 《生物多样性》 CAS CSCD 2002年第2期135-142,共8页
近年来,生物多样性与生态系统功能的关系成为生态学领域内一个重大科学问题。有一些实验研究表明,物种多样性的降低会使生态系统的生产力、稳定性等功能受损。然而对这些实验结果的解释却产生了激烈的争论,因为有两种机制——“生态... 近年来,生物多样性与生态系统功能的关系成为生态学领域内一个重大科学问题。有一些实验研究表明,物种多样性的降低会使生态系统的生产力、稳定性等功能受损。然而对这些实验结果的解释却产生了激烈的争论,因为有两种机制——“生态位互补”和“抽样效应”都可能会产生这种结果。本项研究通过微宇宙实验探讨了物种多样性与生态系统生产力及其可靠度的关系。在10种单细胞藻类中随机抽取物种,构建具有不同物种丰富度的水生群落,并使同一物种丰富度水平的群落之间没有物种交叉,然后检测物种丰富度对群落生产力及其可靠度的作用。群落生产力以藻类干重表示,自实验开始后第4周起,每周测定1次,共测5次。结果显示:物种丰富度对群落生产力有正效应,并且这种正效应随时间推移而增强;许多混合群落的生产力超过了该群落内所有物种的单产,即发生了超产现象;在实验初期某些特定物种对一些混合群落生产力有主要贡献,而在实验后期却没有任何多物种群落的生产力受个别物种存在与否的影响;群落生产力的可靠度与物种丰富度之间不存在显著相关。从以上结果可以得知:物种多样性对群落生产力有逐渐增强的正效应;物种多样性对生产力的正效应是生态位互补和抽样效应共同作用的结果,但随时间推移。 展开更多
关键词 生产力 可靠度 物种多样性 微宇宙实验 生态位互补 抽样效应 物种丰富度 植物群落
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资源互补效应对多样性-生产力关系的影响 被引量:9
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作者 江小雷 张卫国 段争虎 《植物生态学报》 CAS CSCD 北大核心 2005年第4期523-529,共7页
许多有关物种多样性_生态系统功能关系的观察、理论和实验研究都表明, 在局域尺度范围内, 植物种多样性对生态系统生产力存在正效应。然而, 对于促成这种关系的潜在生态学机制却缺乏足够的了解。该实验利用9种一年生栽培牧草, 采用各物... 许多有关物种多样性_生态系统功能关系的观察、理论和实验研究都表明, 在局域尺度范围内, 植物种多样性对生态系统生产力存在正效应。然而, 对于促成这种关系的潜在生态学机制却缺乏足够的了解。该实验利用9种一年生栽培牧草, 采用各物种单播及混播的方法, 构建不同多样性梯度的实验群落, 对物种多样性与生态系统生产力的关系及资源互补效应对系统生产力的影响进行了研究。结果表明, 在一年生植物群落内,植物种多样性在一定程度内对系统生产力存在正效应, 物种多样性与生产力呈二次函数关系, 关系式为y = -98.449x2+1 039.2 x - 42.407, (R2= 0.423 1)。各物种在资源利用、生长速度和竞争能力等功能特征方面存在较大差异, 最高产物种和最低产物种间产量相差5.8倍。在同一多样性梯度内, 不同物种组合的群落间生产力和互补效应也存在较大差异, 说明物种的成分对生态系统生产力也有重要影响。同时,在混播群落中程度不同地存在着资源的互补性利用, 说明物种多样性对系统生产力有增强作用, 但相关分析表明, 互补效应和物种多样性间不存在显著相关关系。互补效应的4种计算方法所反映的资源互补程度有所不同, 每种方法各有利弊, 在对系统的多样性效应作用机制进行评价时, 应根据具体情况, 同时采用几种方法, 以利于对资源互补效应做出恰当的估测。 展开更多
关键词 资源互补效应 物种多样性 生产力 生态系统
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Toward managing mixed-species stands: from parametrization to prescription 被引量:5
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作者 Hans Pretzsch Eric K. Zenner 《Forest Ecosystems》 SCIE CSCD 2017年第4期286-302,共17页
A better understanding and a more quantitative design of mixed-species stands will contribute to more integrative and goal-oriented research in mixed-species forests. Much recent work has indicated that the structure ... A better understanding and a more quantitative design of mixed-species stands will contribute to more integrative and goal-oriented research in mixed-species forests. Much recent work has indicated that the structure and growth of mixed species forests may fundamentally differ from monocultures. Here we suggest how to progress from the present accumulation of phenomenological findings to a design of mixed-species stands and advanced silvicultural prescriptions by means of modelling. First, the knowledge of mixing effects on the structure and growth at the stand, species, and individual tree level is reviewed, with a focus on those findings that are most essential for suitable modelling and silvicultural designs and the regulation of mixed stands as opposed to monocultures. Then, the key role of growth models, stand simulators, and scenario assessments for designing mixed species stands is discussed The next section illustrates that existing forest stand growth models require some fundamental modifications to become suitable for both monocultures and mixed-species stands. We then explore how silvicultural prescriptions derived from scenario runs would need to be both quantified and simplified for transfer to forest management and demonstrated in training plots. Finally, we address the main remaining knowledge gaps that could be remedied through empirical research. 展开更多
关键词 Multiplicative mixing effects overyieldING Overdensity Modelling mixing effects Scenario analysis Silvicultural prescriptions Practical guidelines
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Tree species richness enhances stand productivity while stand structure can have opposite effects, based on forest inventory data from Germany and the United States of America 被引量:3
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作者 Laura Zeller Jingjing Liang Hans Pretzsch 《Forest Ecosystems》 SCIE CSCD 2018年第1期36-52,共17页
Background: in recent studies, mixed forests were found to be more productive than monocultures with everything else remaining the same. Methods: To find out if this productivity is caused by tree species richness, ... Background: in recent studies, mixed forests were found to be more productive than monocultures with everything else remaining the same. Methods: To find out if this productivity is caused by tree species richness, by a more heterogeneous stand structure or both, we analyzed the effects of forest structure and tree species richness on stand productivity, based on inventory data of temperate forests in the United States of America and Germany. Results: Having accounted for effects such as tree size and stand density, we found that: (I) tree species richness increased stand productivity in both countries while the effect of tree size heterogeneity on productivity was negative in Germany but positive in the USA; (11) productivity was highest at sites with an intermediate amount of precipitation; and (111) growth limitations due water scarcity or low temperature may enhance structural heterogeneity. Conclusions: In the context of forest ecosystem goods and services, as well as future sustainable forest resource management, the associated implications would be: 展开更多
关键词 Big data overyieldING Tree size heterogeneity Tree species mixing Climate Biodiversity-productivityrelationship
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Biodiversity, productivity, and temporal stability in a natural grassland ecosystem of China 被引量:3
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作者 Bing Liu WenZhi Zhao +1 位作者 YangYang Meng Chan Liu 《Research in Cold and Arid Regions》 CSCD 2018年第4期293-304,共12页
Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richnes... Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richness and aboveground biomass,and simulated the competitive assemblages in a natural grassland ecosystem of China, aiming to test some assumptions and predictions about biodiversity–stability relationships. Our results show that aboveground productivity and temporal stability increased significantly with increasing species richness, and via a combination of overyielding, species asynchrony, and portfolio effects. Species interactions resulted in overyielding caused by trait-independent complementarity, and were not offset by a negative dominance effect and trait-dependent complementarity effect. Therefore, the mechanisms underlying the biodiversity effect shifted from the selection effect to the complementarity effect as diversity increased, and both effects were coexisted but the complementarity effect represent a mechanism that facilitates long term species coexistence in a natural grassland ecosystem of China. 展开更多
关键词 BIODIVERSITY PRODUCTIVITY TEMPORAL stability overyieldING EFFECT SPECIES interactions complementarity EFFECT selection EFFECT
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不同豆禾混播比例对植物种间关系及草地生产力的影响 被引量:4
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作者 郭川 赵艳兰 +5 位作者 李香君 周冀琼 刘琳 孙飞达 白彦福 马骢毓 《草业科学》 CAS CSCD 北大核心 2022年第11期2307-2316,共10页
选取西南山地丘陵区常见的4种豆禾牧草鸭茅(Dactylis glomerata)、多年生黑麦草(Lolium perenne)、白三叶(Trifolium repens)、红三叶(T.pratense),设置3个豆禾比例[5:5(L_(5)G_(5))、4:6(L_(4)G_(6))、3:7(L_(3)G_(7))]及4种草单播(DG... 选取西南山地丘陵区常见的4种豆禾牧草鸭茅(Dactylis glomerata)、多年生黑麦草(Lolium perenne)、白三叶(Trifolium repens)、红三叶(T.pratense),设置3个豆禾比例[5:5(L_(5)G_(5))、4:6(L_(4)G_(6))、3:7(L_(3)G_(7))]及4种草单播(DG、LP、BP、TP)共7个处理。通过在3和30 cm土层进行^(15)N同位素标定,分析不同混播比例下,由不同固氮潜力及根系深度植物构建的混播及单播群落的相对总产量、竞争强度、土地当量比、超产效应、补偿效应、选择效应、植物氮磷含量、固氮量和固氮率的异同,探究混播草地的生产性能及垂直生态位养分吸收策略,揭示高产稳定混播草地的维持机制。结果表明,相较单播,4种植物混播草地具有明显的超产优势,其中L_(5)G_(5)处理的地上生物量、相对总产量、土地当量比、超产效应和植物全磷含量最高;混播草地中较高的生产力主要受到补偿效应的影响。相较单播,L_(5)G_(5)混播草地中植物在土层3 cm的^(15)N吸收量及豆科固氮量均显著提升(P<0.05),L_(5)G_(5)混播植物在浅层3 cm土壤的氮素吸收量及豆科的固氮量显著高于在深层30 cm土壤(P<0.05)。本研究为西南地区多年生混播草地生产力提升提供了理论基础及技术支撑。 展开更多
关键词 豆禾混播 超产效应 补偿效应 固氮量 氮磷吸收 生态位 种间竞争
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马尾松混交林的超产效应及其影响因素 被引量:2
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作者 林润东 张进如 +3 位作者 李石一宁 姚晓东 王小红 陈光水 《亚热带资源与环境学报》 2022年第1期43-50,共8页
营造马尾松混交林被认为是提高马尾松人工林的生产力和生态服务的理想方法,但马尾松混交林的生产力是否具有超产效应及其影响因素目前仍不清楚。为此,通过收集已报道的26篇文献中50个马尾松混交林林分和树种水平的总生物量及各器官生物... 营造马尾松混交林被认为是提高马尾松人工林的生产力和生态服务的理想方法,但马尾松混交林的生产力是否具有超产效应及其影响因素目前仍不清楚。为此,通过收集已报道的26篇文献中50个马尾松混交林林分和树种水平的总生物量及各器官生物量数据,分析马尾松混交林的超产效应及其影响因素。结果表明:整体上,马尾松混交林的乔木层生物量和地上生物量均显著高于纯林。林分水平乔木层生物量超产44.8%,地上生物量超产49.4%,树种水平马尾松总生物量超产31.3%,地上生物量超产36.9%。混交林中马尾松树高和胸径相比纯林也得到了提高。与纯林相比,混交林中马尾松的树枝生物量分配增加,根生物量分配和根茎比减小,树高/胸高断面积比减小。同时,马尾松混交林的混交效应与林龄呈边缘显著正相关,但与初植密度、混交比例、保留密度、气候因子、小地形等因素均没有显著关系。由meta分析可得,混交林可以提高马尾松生物量的超产效应,促进马尾松的生长发育,优化马尾松林的林分结构。 展开更多
关键词 马尾松 混交林 生物量 超产 META分析
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混播比例对三江源人工草地植被和土壤养分特征的影响 被引量:17
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作者 李文 魏廷虎 +5 位作者 永措巴占 才仁塔次 周玉海 张雁平 李文浩 郭卫兴 《草业学报》 CSCD 北大核心 2021年第12期39-48,共10页
建植混播人工草地是修复三江源黑土滩退化草地的有效措施,但不同混播比例下植被和土壤养分特征的变化尚不明确。以垂穗披碱草、中华羊茅和青海草地早熟禾分别按1∶1∶1(M_(4)),2∶1∶1(M_(5)),1∶2∶1(M_(6)),1∶1∶2(M_(7)),2∶2∶1(M_... 建植混播人工草地是修复三江源黑土滩退化草地的有效措施,但不同混播比例下植被和土壤养分特征的变化尚不明确。以垂穗披碱草、中华羊茅和青海草地早熟禾分别按1∶1∶1(M_(4)),2∶1∶1(M_(5)),1∶2∶1(M_(6)),1∶1∶2(M_(7)),2∶2∶1(M_(8)),2∶1∶2(M_(9))和1∶2∶2(M_(10))建植混播人工草地,并以各组分单播为对照,研究生产力、物种多样性、超产效应、多样性净效应(包括互补效应和选择效应)和土壤养分特征的变化,并采用多准则决策模型-TOPSIS进行综合评价,以筛选最佳混播比例,以期为三江源退化草地生态修复提供科学依据。结果表明:混播处理地上生物量显著高于中华羊茅和青海草地早熟禾单播的生物量,但显著低于垂穗披碱草单播处理,混播处理地上生物量在M_(5)、M_(8)、M_(9)和M_(10)处理较高。而地下生物量在混播处理间无显著差异。混播处理中,仅M_(5)、M_(8)、M_(9)和M_(10)处理存在超产,达40.4~71.1 g·m^(-2)。M_(4)和M_(6)处理的多样性净效应均小于0,说明由于物种竞争导致群落减产。而M_(7)~M_(10)混播处理的多样性净效应均大于0,说明物种生态位的互补使得群落高产。M_(8)和M_(9)处理中互补效应和选择效应共同主导了超产效应,而M_(5)和M_(10)处理中主要由互补作用主导超产效应。表层土壤的有机质、全氮、全磷、速效磷和速效钾含量在M_(6)、M_(7)和M_(10)混播处理中较高。TOPSIS模型综合评价表明,M_(10)混播处理不但可保持较高的生产力,还可显著提高土壤的养分含量,是三江源区人工草地建植的理想混播比例。 展开更多
关键词 人工草地 混播比例 生产力 超产效应 土壤养分 三江源
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HOW MULTISPECIES INTERCROP ADVANTAGE RESPONDS TO WATER STRESS:A YIELDCOMPONENT ECOLOGICAL FRAMEWORK AND ITS EXPERIMENTAL APPLICATION 被引量:2
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作者 Luis GARCIA-BARRIOS Yanus A.DECHNIK-VAZQUEZ 《Frontiers of Agricultural Science and Engineering》 2021年第3期416-431,共16页
Absolute yield and land use efficiency can be higher in multicrops.Though this phenomenon is common,it is not always the case.Also,these two benefits are frequently confused and do not necessarily occur together.Cropp... Absolute yield and land use efficiency can be higher in multicrops.Though this phenomenon is common,it is not always the case.Also,these two benefits are frequently confused and do not necessarily occur together.Cropping choices become more complex when considering that multicrops are subject to strong spatial and temporal variation in average soil moisture,which will worsen with climate change.Intercropping in agroecosystems is expected to buffer this impact by favoring resistance to reduced humidity,but there are few empirical/experimental studies to validate this claim.It is not clear if relatively higher multicrop yield and land use efficiency will persist in the face of reduced soil moisture,and how the relation between these benefits might change.Here,we present a relatively simple framework for analyzing this situation.We propose a relative multicrop resistance(RMR)index that captures all possible scenarios of absolute and relative multicrop overyield under water stress.We dissect the ecological components of RMR to understand the relation between higher multicrop yield and land use efficiency and the ecological causes of different overyield scenarios.We demonstrate the use of this framework with data from a 128 microplot greenhouse experiment with small annual crops,arranged as seven-species multicrops and their corresponding monocrops,all under two contrasting watering regimes.We applied simple but robust statistical procedures to resulting data(based on bootstrap methods)to compare RMR,and its components,between different plants/plant parts.We also provide simple graphical tools to analyze the data. 展开更多
关键词 agroecosystem sustainability crop overyielding intercrop drought resistance overyield ecological components
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中亚热带森林植物多样性增加导致细根生物量“超产” 被引量:38
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作者 刘聪 项文化 +2 位作者 田大伦 方晰 彭长辉 《植物生态学报》 CAS CSCD 北大核心 2011年第5期539-550,共12页
细根在森林生态系统C分配和养分循环过程中发挥着重要作用,但对地下细根与植物多样性之间关系的研究相对较少。该研究选择中亚热带从单一树种的杉木(Cunninghamia lanceolata)人工林到多树种的常绿阔叶林(青冈(Cyclobalanopsis glauca)... 细根在森林生态系统C分配和养分循环过程中发挥着重要作用,但对地下细根与植物多样性之间关系的研究相对较少。该研究选择中亚热带从单一树种的杉木(Cunninghamia lanceolata)人工林到多树种的常绿阔叶林(青冈(Cyclobalanopsis glauca)-石栎(Lithocarpus glaber)林)的不同植物多样性梯度,用根钻法采集细根并测定其生物量,用Win-RHIZO2005C根系分析系统测定细根形态参数,以验证以下3个假设:1)植物种类丰富度高的林分其细根生产存在"地下超产"现象;2)根系空间生态位的分离水平是否随着植物多样性增多而增大?3)细根是否通过形态可塑性对林木竞争做出响应?结果显示:从单一树种的杉木人工林到植物种类较复杂的青冈-石栎常绿阔叶林,0-30cm土层的林分细根总生物量和活细根生物量均呈增加的趋势,即细根总生物量为杉木林(305.20g·m-2)<马尾松(Pinus massoniana)林(374.25g·m-2)<南酸枣(Choerospondias axillaris)林(537.42g·m-2)<青冈林(579.33g·m-2),活细根生物量为杉木林(268.74g·m-2)<马尾松林(299.15g·m-2)<南酸枣林(457.32g·m-2)<青冈林(508.47g·m-2),各森林类型之间的细根总生物量差异显著(p<0.05),但活细根生物量差异不显著。土壤垂直剖面上,除杉木林细根生物量随土层变化不显著外,其他森林类型的活细根生物量和总细根生物量均随土层变化显著,表层细根生物量随树种多样性的升高呈减小趋势,据此推测树种间的生态位分离水平逐渐增大。植物多样性的不同对林分的细根形态及空间分布格局影响不显著,细根形态可塑性对生物量变化响应不明显。 展开更多
关键词 生物量 细根 形态 “超产”现象 植物多样性 中亚热带
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Leaf area increases with species richness in young experimental stands of subtropical trees 被引量:13
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作者 Siyi Peng Bernhard Schmid +1 位作者 Josephine Haase Pascal A.Niklaus 《Journal of Plant Ecology》 SCIE CSCD 2017年第1期128-135,共8页
Aims Most biodiversity-ecosystem functioning research has been carried out in grassland ecosystems,and little is known about whether forest ecosystems,in particular outside the temperate zone,respond similarly.Here,we... Aims Most biodiversity-ecosystem functioning research has been carried out in grassland ecosystems,and little is known about whether forest ecosystems,in particular outside the temperate zone,respond similarly.Here,we tested whether productivity,assessed as leaf area index(LAI),increases with species richness in young experimental stands of subtropical trees,whether this response is similar for early-season leaf area(which is dominated by evergreens)and seasonal leaf area increase(which is dominated by deciduous species),and whether responses saturate at high species richness.Methods We used a planted tree biodiversity experiment in south-east China to test our hypotheses.LAI was determined three times by digital hemispheric photography in 144 plots that had been planted with 400 trees each,forming communities with 1,2,4,8 or 16 tree species.Important Findings LAI increased significantly with tree species richness in the fifth year of stand establishment.Similar,but weaker,statistically non-significant trends were observed 1 year before.We did not observe leaf area overyielding and the presence of particularly productive and unproductive species explained large amounts of variation in leaf area,suggesting that selection-type effects contributed substantially to the biodiversity effects we found in this early phase of stand establishment.Effects sizes were moderate to large and comparable in magnitude to the ones reported for grassland ecosystems.Subtropical(and tropical)forests harbor substantial parts of global net primary production and are critical for the Earth’s carbon and hydrological cycle,and our results suggest that tree diversity critically supports these ecosystem services. 展开更多
关键词 BEF-China digital hemispheric photography field biodiversity experiment overyieldING subtropical forest
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Effects of monoculture-conditioned soils on common tallgrass prairie species productivity
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作者 Thomas P.McKenna Brian J.Darby Kathryn A.Yurkonis 《Journal of Plant Ecology》 SCIE CSCD 2019年第3期474-484,共11页
Aims Within biodiversity-ecosystem function experiments,it is widely understood that yields of some species rapidly decline when planted in monoculture.This effect may arise due to decreased access to soil nutrients o... Aims Within biodiversity-ecosystem function experiments,it is widely understood that yields of some species rapidly decline when planted in monoculture.This effect may arise due to decreased access to soil nutrients or an increase in detrimental soil patho-gens within monoculture plantings.To determine whether or not soil conditioning affects tall grass prairie species biomass produc-tion,we conducted a field experiment to assess species growth in conspecifically and heterospecifically conditioned soils and a greenhouse experiment to elucidate how conspecific soil biota affected species growth.Methods To test for species-specific soil effects,seedlings of the legume Astragulus canadensis,the cool-season grass Elymus canaden-sis,the forb Helianthus maximiliani and the warm-season grass Panicum virgatum were grown in field plots that had either been conspecifically or heterospecifically conditioned over 2 years.Plant growth was recorded over a single growing season,and soils were assessed for differences in their nematode(mesofauna)communities.Seedlings of these species were additionally grown over a 6-week period in conspecifically conditioned soil that was either untreated,heated to 60°C,sterilized(autoclaved at 120°C)or heated to 60°C and reinoculated with conspecific soil biota.The two heating treatments were used to compare growth responses between a low-and high-temperature soil treatment.The reinoculation treatment was used to assess the effect of soil biota in light of any nutrient changes that may have occurred with soil heating.Important Findings Elymus canadensis,H.maximiliani and P.virgatum growth was improved in field plots conditioned by the legume A.canadensis com-pared with their growth in conspecifically conditioned(home)soils.Despite variation(grass versus nongrass)in their soil nematode com-munities,there was no evidence to suggest that these three species were inhibited by conspecific or functionally conspecific soil condi-tioning in the field.Astragulus canadensis was the only species whose growth was reduced in conspecifically conditioned field soil.In the greenhouse,E.canadensis growth increased in all of the heat-treated soils,likely a response to a fertilization effect associated with soil heat-ing.Panicum virgatum growth also increased among the heated soils.However,its growth decreased in heated soils where conspecific soil mesofauna were reintroduced,indicating that this grass may be inhib-ited by soil mesofauna.Finally,A.canadensis growth decreased in soils treated to fully remove soil biota and was not affected by rein-troduction of soil mesofauna,suggesting that this species negatively responds to soil changes that occur with extreme heating.At least for the suite of tallgrass prairie species evaluated within this experiment,it appears that changes in soil chemistry and generalist soil biota,as opposed to increasing species-specific soil pathogens,more strongly contribute to temporal disparities in their performance. 展开更多
关键词 Astragulus canadensis DIVERSITY Elymus canadensis Helianthus maximiliani MONOCULTURE overyieldING Panicum virgatum PRODUCTIVITY soil biota soil conditioning
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一年生和多年生豆禾混播草地超产与多样性效应的比较 被引量:11
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作者 黎松松 王宁欣 +4 位作者 郑伟 朱亚琼 王祥 马军 朱进忠 《植物生态学报》 CAS CSCD 北大核心 2021年第1期23-37,共15页
为了测度一年生和多年生豆禾混播草地的超产效应与植物多样性效应的关系,明确一年生和多年生混播草地的高产优势,探索豆禾混播草地多样性效应和超产效应对其生态功能的响应机制,于2013–2015年在新疆伊犁地区昭苏盆地开展了3年的牧草产... 为了测度一年生和多年生豆禾混播草地的超产效应与植物多样性效应的关系,明确一年生和多年生混播草地的高产优势,探索豆禾混播草地多样性效应和超产效应对其生态功能的响应机制,于2013–2015年在新疆伊犁地区昭苏盆地开展了3年的牧草产量观测试验。该试验设置3种牧草混播种类和混播比例,分别为一年生豆禾混播草地(2种牧草混播, AM2)和多年生豆禾混播草地(2种牧草混播, PM2;4种牧草混播, PM4;6种牧草混播, PM6),豆禾混播比例分别为6:4、5:5和4:6。结果表明:1) 2013、2014年和3年平均值AM2的超产幅度小于PM2和PM6, 2015年AM2的超产幅度大于PM2、PM4和PM6;混播群落生产力与群落组分中生产力最高产物种单产以及各组分种平均单产的差值表现出相似的规律。2) 2013、2014年和3年平均值AM2的互补效应大于PM2、PM4和PM6,AM2的选择效应则远小于互补效应,PM2、PM4和PM6的互补效应则比较稳定。3)物种丰富度和物种均匀度与牧草产量(群落生产力)大部分情况下呈单峰的"饱和上升型"模式,分别在4种牧草混播和豆禾混播比例为5:5时,具有较高生产力。4)多年生豆禾混播草地的互补效应、选择效应和多样性净效应均随生长年限的延长而呈下降趋势,也导致了超产幅度、超产效应及其稳定性的下降。由此可见,在建植初期,互补效应和选择效应共同主导了多年生豆禾混播草地的超产效应,而随着生长年限的延长,选择效应则成为主要影响因素;一年生豆禾混播草地的超产效应则一直受互补效应的影响。 展开更多
关键词 物种丰富度 物种均匀度 超产效应 互补效应 选择效应 多样性净效应 生长年限
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温带针阔混交林生物量稳定性影响机制 被引量:3
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作者 于水今 王娟 +1 位作者 张春雨 赵秀海 《植物生态学报》 CAS CSCD 北大核心 2022年第6期632-641,共10页
森林生态系统通过响应环境波动和干扰而产生时间变化,对其稳定性机制的研究有利于生态系统服务。温带针阔混交林是全球森林生态系统的重要组成部分,该研究致力于探索超产效应、林分结构、物种异步性及优势物种稳定性对温带天然针阔混交... 森林生态系统通过响应环境波动和干扰而产生时间变化,对其稳定性机制的研究有利于生态系统服务。温带针阔混交林是全球森林生态系统的重要组成部分,该研究致力于探索超产效应、林分结构、物种异步性及优势物种稳定性对温带天然针阔混交林群落稳定性的影响,以明确主要影响机制。该研究分别设定物种丰富度、胸径变异系数、物种异步性和优势物种稳定性为解释变量,群落生物量稳定性、生物量平均值和生物量标准差为响应变量,构建3个结构方程模型,比较各变量间直接与间接效应的相对大小。主要结果为:(1)结构方程模型提供了良好的拟合效果,并占群落生物量稳定性变化的40.6%;(2)物种丰富度与生物量平均值、生物量标准差均呈显著负相关关系,路径系数分别为–0.103和–0.061;(3)胸径变异系数与群落生物量稳定性及生物量平均值均呈显著负相关关系,路径系数分别为–0.123和–0.097;(4)物种异步性与群落生物量稳定性、生物量平均值、生物量标准差均呈显著正相关关系,路径系数分别为0.055、0.085和0.055;(5)优势物种稳定性与群落生物量稳定性和生物量平均值呈显著正相关关系,路径系数分别为0.623和0.085,与生物量标准差间显著负相关,路径系数为–0.608。研究结果表明尽管林分结构和物种异步性对温带针阔混交林群落生物量稳定性均有显著影响,但优势物种稳定性是最主要的直接影响因素。 展开更多
关键词 群落生物量稳定性 超产效应 林分结构 物种异步性 优势物种稳定性
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