Aims Plants use different types of responses such as tolerance and induced defense to mitigate the effects of herbivores.The direc-tion and magnitude of both these plant responses can vary with plant age.However,most ...Aims Plants use different types of responses such as tolerance and induced defense to mitigate the effects of herbivores.The direc-tion and magnitude of both these plant responses can vary with plant age.However,most studies have focused on aboveground herbivory,whereas important feeding occurs belowground.Here,we tested the hypothesis that plant tolerance and defense following shoot damage or root herbivory depends on plant age.Methods In order to test our hypothesis,we exposed the perennial grass spe-cies Holcus lanatus to defoliation and root nematode inoculation at three growth stages(young,intermediate and old plants),and exam-ined responses of plant traits related to tolerance(regrowth follow-ing defoliation)and defense(leaf and root nitrogen and phenolics).Important Findings Defoliation overall reduced plant shoot and root biomass as well as foliar concentrations of phenolics regardless of plant age at defoli-ation.In contrast,defoliation increased foliar N concentrations,but only when defoliation occurred at intermediate and old plant age.Inoculation with root-feeding nematodes reduced root N concentra-tions after a prolonged period of growth,but only when nematodes had been inoculated when plants were young.The relative shoot re-growth rate of plants increased immediately after defoliation but this was independent of the plant age at which defoliation occurred,i.e.was not stronger in plants that were defoliated at a more advanced age,as hypothesized.Similarly,relative root growth rates increased shortly after defoliation,but this was only observed for plants defoli-ated when they were young.We conclude that plant responses to aboveground and belowground herbivory in traits related to both defense and tolerance are affected by plant age,but do not gener-ally change with plant age.展开更多
Changes in soil chemistry after invasion by bracken(Pteridium aquilinum)have been studied in heathlands,but comparable studies in meadows are lacking.We investigated if bracken invasion into P-deficient meadows alters...Changes in soil chemistry after invasion by bracken(Pteridium aquilinum)have been studied in heathlands,but comparable studies in meadows are lacking.We investigated if bracken invasion into P-deficient meadows alters the soil nutrient-resource pool,as well as the mechanisms behind it linked to soil processes and bracken nutrition.Furthermore,we investigated how community composition responds to differences in soil chemistry before and after the invasion.Soil and plant material sampling,along with vegetation survey,were performed during bracken peak biomass.Data analyses included analysis of variance and canonical correspondence analysis(CCA).Bracken invasion increased soil P availability,soil organic C concentration,as well as C:N,C:S and N:S ratios,while decreasing Fe and Co concentrations.Bracken pinnae were rich in P,and its rhizomes were rich in K,whereas N:P of pinnae and rhizomes was low.CCA showed contrasting abundance patterns of frequent meadow species related to P and K availability.Holcus lanatus exhibited competitive advantage under extremely low P availability.Increase in P availability under bracken may have occurred through promoting the leaching of Fe and Al.By increasing P availability for its growth and increasing N limitation for other species,bracken can gain a competitive advantage from the soil resource-niche perspective.Its ability to increase soil P availability,along with the physiological mechanisms behind its high P acquisition efficiency,seem to differentiate bracken from other species of competitive ecological strategy,which are mainly confined to nutrient-rich environments.This enabled bracken to invade P-deficient meadows.展开更多
基金This work was funded by a grant from the China Scholarship Council(no.2011630083 to M.G.W.).This is NIOO-KNAW publication number 6340.
文摘Aims Plants use different types of responses such as tolerance and induced defense to mitigate the effects of herbivores.The direc-tion and magnitude of both these plant responses can vary with plant age.However,most studies have focused on aboveground herbivory,whereas important feeding occurs belowground.Here,we tested the hypothesis that plant tolerance and defense following shoot damage or root herbivory depends on plant age.Methods In order to test our hypothesis,we exposed the perennial grass spe-cies Holcus lanatus to defoliation and root nematode inoculation at three growth stages(young,intermediate and old plants),and exam-ined responses of plant traits related to tolerance(regrowth follow-ing defoliation)and defense(leaf and root nitrogen and phenolics).Important Findings Defoliation overall reduced plant shoot and root biomass as well as foliar concentrations of phenolics regardless of plant age at defoli-ation.In contrast,defoliation increased foliar N concentrations,but only when defoliation occurred at intermediate and old plant age.Inoculation with root-feeding nematodes reduced root N concentra-tions after a prolonged period of growth,but only when nematodes had been inoculated when plants were young.The relative shoot re-growth rate of plants increased immediately after defoliation but this was independent of the plant age at which defoliation occurred,i.e.was not stronger in plants that were defoliated at a more advanced age,as hypothesized.Similarly,relative root growth rates increased shortly after defoliation,but this was only observed for plants defoli-ated when they were young.We conclude that plant responses to aboveground and belowground herbivory in traits related to both defense and tolerance are affected by plant age,but do not gener-ally change with plant age.
文摘Changes in soil chemistry after invasion by bracken(Pteridium aquilinum)have been studied in heathlands,but comparable studies in meadows are lacking.We investigated if bracken invasion into P-deficient meadows alters the soil nutrient-resource pool,as well as the mechanisms behind it linked to soil processes and bracken nutrition.Furthermore,we investigated how community composition responds to differences in soil chemistry before and after the invasion.Soil and plant material sampling,along with vegetation survey,were performed during bracken peak biomass.Data analyses included analysis of variance and canonical correspondence analysis(CCA).Bracken invasion increased soil P availability,soil organic C concentration,as well as C:N,C:S and N:S ratios,while decreasing Fe and Co concentrations.Bracken pinnae were rich in P,and its rhizomes were rich in K,whereas N:P of pinnae and rhizomes was low.CCA showed contrasting abundance patterns of frequent meadow species related to P and K availability.Holcus lanatus exhibited competitive advantage under extremely low P availability.Increase in P availability under bracken may have occurred through promoting the leaching of Fe and Al.By increasing P availability for its growth and increasing N limitation for other species,bracken can gain a competitive advantage from the soil resource-niche perspective.Its ability to increase soil P availability,along with the physiological mechanisms behind its high P acquisition efficiency,seem to differentiate bracken from other species of competitive ecological strategy,which are mainly confined to nutrient-rich environments.This enabled bracken to invade P-deficient meadows.
