Aims Although ecological interactions are often conceptualized and stud-ied in a pairwise framework,ecologists recognize that the outcomes of these interactions are influenced by other members of the com-munity.Intera...Aims Although ecological interactions are often conceptualized and stud-ied in a pairwise framework,ecologists recognize that the outcomes of these interactions are influenced by other members of the com-munity.Interactions(i)between plants and insect herbivores and(I)between plants and mycorrhizal fungi are ubiquitous in terrestrial ecosystems and may be linked via common host plants.Previous studies suggest that colonization by arbuscular mycorrhizal fungi(AMF)can modifty plants'induced responses to herbivore attack,but these indirect effects of fungal symbionts are poorly understood.I investigated the role of AMF in induced plant response to a gen-eralist herbivore.Methods|manipulated AMF status and herbivory in Cucumis sativus L.(cucumber,Cucurbitaceae)in a greenhouse to investigate induced responses in the presence and absence of the mycorrhi-zal fungus Glomus intraradices(Glomeraceae).Spodoptera exigua Habner(Noctuidae)were used to manipulate prior damage and later as assay caterpillars.I also measured G.intraradices and her-bivory effects on plant N and effects on plant growth.Impor tant Findings AMF status affected the induced response of C.sativus,underscor-ing the importance of incorporating the roles of plant symbionts into plant defense theory.Assay caterpillars ate significantly more leaf tissue only on mycorrhizal plants that had experienced prior damage.Despite more consumption,biomass change in these cat-erpillars did not differ from those feeding on plants with other treat-ment combinations.Leaf N content was reduced by G.intraradices but unaffected by herbivory treatments,suggesting that the observed differences in assay caterpillar feeding were due to changes in defensive chemistry that depended on AMF.展开更多
Aims Climate change is predicted to cause both increased temperatures and changes in precipitation,leading to more severe droughts in some areas.How these changes will affect plant growth may depend in part on biotic ...Aims Climate change is predicted to cause both increased temperatures and changes in precipitation,leading to more severe droughts in some areas.How these changes will affect plant growth may depend in part on biotic context.Most vascular plants form symbiotic rela-tionships with arbuscular mycorrhizal fungi(AMF),root symbionts that provide soil nutrients to plants in exchange for carbohydrates,which may reduce the effects of environmental stresses on plants.We investigated if AMF modified temperature and drought effects on plant growth,fitness and defenses against herbivory.Methods We manipulated AMF presence,temperature and water availability on bell pepper plants(Capsicum annuum L.)in a field setting to measure plant growth and fitness responses.In a growth chamber experiment,we also investigated if AMF influenced insect herbi-vores feeding on plants at elevated temperatures.Important findings Drought consistently reduced plant growth,and AMF did not change drought impacts.However,with sufficient water,AMF tended to benefit plant growth and flower production(but not fruit production)compared to non-mycorrhizal plants.In the growth chamber,temperature and AMF influenced plant protein and phos-phorus contents,but not defensive chemistry or herbivore perfor-mance.Thus,AMF may ameliorate the effects of temperature stress due to climate change on plants by increasing growth and nutrient content,but these effects do not extend to the constitutive herbivory defenses examined here.展开更多
Aims The majority of angiosperms are pollinated by animals,and this interaction is of enormous importance in both agricultural and natural systems.Pollinator behavior is influenced by plants’floral traits,and these t...Aims The majority of angiosperms are pollinated by animals,and this interaction is of enormous importance in both agricultural and natural systems.Pollinator behavior is influenced by plants’floral traits,and these traits may be modified by interactions with other community members.In recent years,knowledge of ecological linkages between above-and belowground organ-isms has grown tremendously.Soil communities are extremely diverse,and when their interactions with plants influence floral characteristics,they have the potential to alter pollinator attrac-tion and visitation,but plant-pollinator interactions have been neglected in studies of the direct and indirect effects of soil organism-root interactions.Here,we review these belowground interactions,focusing on the effects of nitrogen-fixing bacteria,arbuscular mycorrhizal fungi and root-feeding herbivores,and their effects on floral traits and pollinators.Further,we identify gaps in our knowledge of these indirect effects and recommend promising directions and topics that should be addressed by future research.Important Findings Belowground organisms can influence a wide variety of floral traits that are important mediators of pollinator attraction,including the number and size of flowers and nectar and pollen production.Other traits that are known to influence pollinators in some plant species,such as floral volatiles,color and nectar composition,have rarely or never been examined in the context of belowground plant interac-tions.Despite clear effects on flowers,relatively few studies have measured pollinator responses to belowground interactions.When these indirect effects have been studied,both arbuscular mycorrhi-zal fungi and root herbivores were found to shift pollinator visitation patterns.Depending on the interaction,these changes may either increase or decrease pollinator attraction.Finally,we discuss future directions for ecological studies that will more fully integrate below-ground ecology with pollination biology.We advocate a multilevel approach 展开更多
Aims Chalk grasslands are subject to vegetation dynamics that range from species-rich open grasslands to tall and encroached grasslands,and woods and forests.In grasslands,earthworms impact plant communities and ecosy...Aims Chalk grasslands are subject to vegetation dynamics that range from species-rich open grasslands to tall and encroached grasslands,and woods and forests.In grasslands,earthworms impact plant communities and ecosystem functioning through the modification of soil physical,chemical and microbiological properties,but also through their selective ingestion and vertical transportation of seeds from the soil seed bank.Laboratory experiments showed that seed-earthworm interactions are species specific,but little is known on the impact of seed-earthworm interactions in the field.The overall aim of this study was to better understand seed-earthworm interactions and their impact on the plant community.First we analyzed the composition of seedlings emerging from casts after earthworm ingestion.Then we compared seedling composition in casts to the plant composition of emerging seedlings from the soil and of the aboveground vegetation along four stages of the secondary succession of chalk grasslands.Methods Four stages of the secondary succession of a chalk grassland—from open sward to woods—were sampled in Upper Normandy,France,in February 2010.Within each successional stage(×3 replicates),we sampled the standing vegetation,soil seed bank at three soil depths(0-2,2-5 and 5-10 cm)and earthworm surface casts along transects.Soil and cast samples were water sieved before samples were spread onto trays and placed into a greenhouse.Emerging seedlings were counted and identified.Effect of successional stage and origin of samples on mean and variability of abundance and species richness of seedlings emerging from casts and soil seed banks were analyzed.Plant compositions were compared between all sample types.We used generalized mixed-effect models and a distance-based redundancy multivariate analysis.Important Findings Seedling abundance was always higher in earthworm casts than in the soil seed bank and increased up to 5-fold,4-fold and 3.5-fold,respectively,in the tall grassland,woods and encroached grassland compared t展开更多
Aims Intensive land management practices can compromise soil biodiversity,thus jeopardizing long-term soil productivity.Arbuscular mycorrhizal fungi(AMF)play a pivotal role in promoting soil productivity through oblig...Aims Intensive land management practices can compromise soil biodiversity,thus jeopardizing long-term soil productivity.Arbuscular mycorrhizal fungi(AMF)play a pivotal role in promoting soil productivity through obligate symbiotic associations with plants.However,it is not clear how properties of plant communities,especially species richness and composition influence the viability of AMF populations in soils.Methods Here we test whether monocultures of eight plant species from different plant functional groups,or a diverse mixture of plant species,maintain more viable AMF propagules.To address this question,we extracted AMF spores from 12-year old plant monocultures and mixtures and paired single AMF spores with single plants in a factorial design crossing AMF spore origin with plant species identity.Important Findings AMF spores from diverse plant mixtures were more successful at colonizing multiple plant species and plant individuals than AMF spores from plant monocultures.Furthermore,we found evidence that AMF spores originating from diverse mixtures more strongly increased biomass than AMF from monocultures in the legume Trifolium repens L.AMF viability and ability to interact with many plant species were greater when AMF spores originated from 12-year old mixtures than monocultures.Our results show for the first time that diverse plant communities can sustain AMF viability in soils and demonstrate the potential of diverse plant communities to maintain viable AMF propagules that are a key component to soil health and productivity.展开更多
In nature,plant communities are affected simultaneously by a variety of functionally dissimilar organisms both above and below the ground.However,there is a gap of knowledge on interactive effects of functionally diss...In nature,plant communities are affected simultaneously by a variety of functionally dissimilar organisms both above and below the ground.However,there is a gap of knowledge on interactive effects of functionally dissimilar organisms on plant communities that is needed to be filled to better understand and predict the general impact of biotic factors on plant communities.Methods We conducted a full-factorial mesocosm study to investigate the individual and combined impacts of above-and belowground functionally dissimilar organisms on a grassland plant community.We studied the effects of aboveground herbivores(Helix aspersa,Gastropoda),arbuscular mycorrhizal fungi(AMF;Glomus spp.,Glomeromycota)and endogeic earthworms(Aporrectodea spp.,Lumbricidae)on the diversity,structure and productivity of an experimental grassland plant community and each other.Important Findings Aboveground herbivory by snails decreased,AMF increased and earthworms had no effects on the diversity of the grassland plant community,while their combined effects were additive.The biomass of the plant community was negatively affected by snails and AMF,while no effects of earthworms or interaction effects were found.The plant species were differently affected by snails and AMF.No effects of the above-and belowground organisms on each other’s performance were detected.Since the effects of the functionally dissimilar organisms on the grassland plant community were mainly independent,the results indicate that their combined effects may be predicted by knowing the individual effects,at least under the conditions used in the present mesocosm study.展开更多
基金U.S.Department of Agriculture(NRI 2008-02346)Northern Illinois University Department of Biological Sciencesthe Northern Illinois University Institute for the Study of the Environment,Sustainability,and Energy.
文摘Aims Although ecological interactions are often conceptualized and stud-ied in a pairwise framework,ecologists recognize that the outcomes of these interactions are influenced by other members of the com-munity.Interactions(i)between plants and insect herbivores and(I)between plants and mycorrhizal fungi are ubiquitous in terrestrial ecosystems and may be linked via common host plants.Previous studies suggest that colonization by arbuscular mycorrhizal fungi(AMF)can modifty plants'induced responses to herbivore attack,but these indirect effects of fungal symbionts are poorly understood.I investigated the role of AMF in induced plant response to a gen-eralist herbivore.Methods|manipulated AMF status and herbivory in Cucumis sativus L.(cucumber,Cucurbitaceae)in a greenhouse to investigate induced responses in the presence and absence of the mycorrhi-zal fungus Glomus intraradices(Glomeraceae).Spodoptera exigua Habner(Noctuidae)were used to manipulate prior damage and later as assay caterpillars.I also measured G.intraradices and her-bivory effects on plant N and effects on plant growth.Impor tant Findings AMF status affected the induced response of C.sativus,underscor-ing the importance of incorporating the roles of plant symbionts into plant defense theory.Assay caterpillars ate significantly more leaf tissue only on mycorrhizal plants that had experienced prior damage.Despite more consumption,biomass change in these cat-erpillars did not differ from those feeding on plants with other treat-ment combinations.Leaf N content was reduced by G.intraradices but unaffected by herbivory treatments,suggesting that the observed differences in assay caterpillar feeding were due to changes in defensive chemistry that depended on AMF.
基金This work was supported in part by a Research and Artistry Opportunity Grant from Northern Illinois University.
文摘Aims Climate change is predicted to cause both increased temperatures and changes in precipitation,leading to more severe droughts in some areas.How these changes will affect plant growth may depend in part on biotic context.Most vascular plants form symbiotic rela-tionships with arbuscular mycorrhizal fungi(AMF),root symbionts that provide soil nutrients to plants in exchange for carbohydrates,which may reduce the effects of environmental stresses on plants.We investigated if AMF modified temperature and drought effects on plant growth,fitness and defenses against herbivory.Methods We manipulated AMF presence,temperature and water availability on bell pepper plants(Capsicum annuum L.)in a field setting to measure plant growth and fitness responses.In a growth chamber experiment,we also investigated if AMF influenced insect herbi-vores feeding on plants at elevated temperatures.Important findings Drought consistently reduced plant growth,and AMF did not change drought impacts.However,with sufficient water,AMF tended to benefit plant growth and flower production(but not fruit production)compared to non-mycorrhizal plants.In the growth chamber,temperature and AMF influenced plant protein and phos-phorus contents,but not defensive chemistry or herbivore perfor-mance.Thus,AMF may ameliorate the effects of temperature stress due to climate change on plants by increasing growth and nutrient content,but these effects do not extend to the constitutive herbivory defenses examined here.
文摘Aims The majority of angiosperms are pollinated by animals,and this interaction is of enormous importance in both agricultural and natural systems.Pollinator behavior is influenced by plants’floral traits,and these traits may be modified by interactions with other community members.In recent years,knowledge of ecological linkages between above-and belowground organ-isms has grown tremendously.Soil communities are extremely diverse,and when their interactions with plants influence floral characteristics,they have the potential to alter pollinator attrac-tion and visitation,but plant-pollinator interactions have been neglected in studies of the direct and indirect effects of soil organism-root interactions.Here,we review these belowground interactions,focusing on the effects of nitrogen-fixing bacteria,arbuscular mycorrhizal fungi and root-feeding herbivores,and their effects on floral traits and pollinators.Further,we identify gaps in our knowledge of these indirect effects and recommend promising directions and topics that should be addressed by future research.Important Findings Belowground organisms can influence a wide variety of floral traits that are important mediators of pollinator attraction,including the number and size of flowers and nectar and pollen production.Other traits that are known to influence pollinators in some plant species,such as floral volatiles,color and nectar composition,have rarely or never been examined in the context of belowground plant interac-tions.Despite clear effects on flowers,relatively few studies have measured pollinator responses to belowground interactions.When these indirect effects have been studied,both arbuscular mycorrhi-zal fungi and root herbivores were found to shift pollinator visitation patterns.Depending on the interaction,these changes may either increase or decrease pollinator attraction.Finally,we discuss future directions for ecological studies that will more fully integrate below-ground ecology with pollination biology.We advocate a multilevel approach
基金Upper Normandy region and the SCALE research network.
文摘Aims Chalk grasslands are subject to vegetation dynamics that range from species-rich open grasslands to tall and encroached grasslands,and woods and forests.In grasslands,earthworms impact plant communities and ecosystem functioning through the modification of soil physical,chemical and microbiological properties,but also through their selective ingestion and vertical transportation of seeds from the soil seed bank.Laboratory experiments showed that seed-earthworm interactions are species specific,but little is known on the impact of seed-earthworm interactions in the field.The overall aim of this study was to better understand seed-earthworm interactions and their impact on the plant community.First we analyzed the composition of seedlings emerging from casts after earthworm ingestion.Then we compared seedling composition in casts to the plant composition of emerging seedlings from the soil and of the aboveground vegetation along four stages of the secondary succession of chalk grasslands.Methods Four stages of the secondary succession of a chalk grassland—from open sward to woods—were sampled in Upper Normandy,France,in February 2010.Within each successional stage(×3 replicates),we sampled the standing vegetation,soil seed bank at three soil depths(0-2,2-5 and 5-10 cm)and earthworm surface casts along transects.Soil and cast samples were water sieved before samples were spread onto trays and placed into a greenhouse.Emerging seedlings were counted and identified.Effect of successional stage and origin of samples on mean and variability of abundance and species richness of seedlings emerging from casts and soil seed banks were analyzed.Plant compositions were compared between all sample types.We used generalized mixed-effect models and a distance-based redundancy multivariate analysis.Important Findings Seedling abundance was always higher in earthworm casts than in the soil seed bank and increased up to 5-fold,4-fold and 3.5-fold,respectively,in the tall grassland,woods and encroached grassland compared t
基金supported by the German Research Foundation(RO2397/7)conducted in the framework of the Jena Experiment(FOR 456/1451)+1 种基金with additional support from the Friedrich Schiller University of JenaFurther support was provided by the German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig,funded by the German Research Foundation(FZT 118).
文摘Aims Intensive land management practices can compromise soil biodiversity,thus jeopardizing long-term soil productivity.Arbuscular mycorrhizal fungi(AMF)play a pivotal role in promoting soil productivity through obligate symbiotic associations with plants.However,it is not clear how properties of plant communities,especially species richness and composition influence the viability of AMF populations in soils.Methods Here we test whether monocultures of eight plant species from different plant functional groups,or a diverse mixture of plant species,maintain more viable AMF propagules.To address this question,we extracted AMF spores from 12-year old plant monocultures and mixtures and paired single AMF spores with single plants in a factorial design crossing AMF spore origin with plant species identity.Important Findings AMF spores from diverse plant mixtures were more successful at colonizing multiple plant species and plant individuals than AMF spores from plant monocultures.Furthermore,we found evidence that AMF spores originating from diverse mixtures more strongly increased biomass than AMF from monocultures in the legume Trifolium repens L.AMF viability and ability to interact with many plant species were greater when AMF spores originated from 12-year old mixtures than monocultures.Our results show for the first time that diverse plant communities can sustain AMF viability in soils and demonstrate the potential of diverse plant communities to maintain viable AMF propagules that are a key component to soil health and productivity.
文摘In nature,plant communities are affected simultaneously by a variety of functionally dissimilar organisms both above and below the ground.However,there is a gap of knowledge on interactive effects of functionally dissimilar organisms on plant communities that is needed to be filled to better understand and predict the general impact of biotic factors on plant communities.Methods We conducted a full-factorial mesocosm study to investigate the individual and combined impacts of above-and belowground functionally dissimilar organisms on a grassland plant community.We studied the effects of aboveground herbivores(Helix aspersa,Gastropoda),arbuscular mycorrhizal fungi(AMF;Glomus spp.,Glomeromycota)and endogeic earthworms(Aporrectodea spp.,Lumbricidae)on the diversity,structure and productivity of an experimental grassland plant community and each other.Important Findings Aboveground herbivory by snails decreased,AMF increased and earthworms had no effects on the diversity of the grassland plant community,while their combined effects were additive.The biomass of the plant community was negatively affected by snails and AMF,while no effects of earthworms or interaction effects were found.The plant species were differently affected by snails and AMF.No effects of the above-and belowground organisms on each other’s performance were detected.Since the effects of the functionally dissimilar organisms on the grassland plant community were mainly independent,the results indicate that their combined effects may be predicted by knowing the individual effects,at least under the conditions used in the present mesocosm study.
