Wastewater with relatively high nitrogen concentrations is a major source of nitrous oxide(N_2O) and methane(CH_4) emissions and exerts multiple stresses on the environment.Studies have shown that plant diversity play...Wastewater with relatively high nitrogen concentrations is a major source of nitrous oxide(N_2O) and methane(CH_4) emissions and exerts multiple stresses on the environment.Studies have shown that plant diversity plays an important role in ecosystem functioning.However, the effects of plant species diversity on CH_4 and N_2O emissions under high ammonium(NH_4^+-N) loading rates remain unclear. In this study, a microcosm experiment simulating vertical constructed wetlands supplied with high NH_4^+-N water levels was established. The treatments included four species richness levels(1, 2, 3, 4) and 15 species compositions. There was no significant relationship between species richness and N_2O emissions. However, N_2O emissions were significantly reduced by specific plant species composition. Notably, the communities with the presence of Rumex japonicus L. reduced N_2O emissions by 62% compared to communities without this species. This reduction in N_2O emissions may have been a result of decreased N concentrations and increased plant biomass. CH_4 emissions did not respond to plant species richness or species identity.Overall, plant species identity surpassed species richness in lowering N_2O emissions from constructed wetlands with high NH_4^+-N water. The results also suggest that communities with R. japonicus could achieve higher N removal and lower greenhouse gas emissions than other wetland species.展开更多
Mixed-species plantations generally exhibit higher ecosystem multifunctionality than monospecific plantations.However,it is unclear how tree species functional composition influences species mixture effects on ecosyst...Mixed-species plantations generally exhibit higher ecosystem multifunctionality than monospecific plantations.However,it is unclear how tree species functional composition influences species mixture effects on ecosystem multifunctionality.We selected 171 monospecific and mixed-species plantations from nine regions across subtropical China,and quantified 13 key ecosystem functional properties to investigate how species mixture effects on ecosystem multifunctionality are modulated by functional diversity and identity.We found that ecosystem multifunctionality was significantly higher(p<0.05)in mixed tree plantations than in monospecific plantations except the mixed-conifer species plantations.Across all regions,ecosystem multifunctionality was significantly higher(p<0.05)in mixed conifer-broadleaf plantations than in monospecific plantations of the corresponding species,but not different between mixed and monospecific coniferous plantations.The magnitude of species mixture effects on ecosystem multifunctionality varied greatly with tree species compositions.Taking Cunninghamia lanceolata Lamb.as an example,the effects varied from a range of 2.0%–9.6%when mixed with a conifer species to 36%–87%when mixed with a broadleaf species.The functional diversity was the dominate driver shaping ecosystem multifunctionality,while functional identity,as expressed by community-weighted mean of specific leaf area,also had a positive effect on ecosystem multifunctionality through the increased below-ground nitrogen and phosphorus stocks regulated by specific leaf area of the mixing tree species.Our study highlights the important role of functional diversity in shaping ecosystem multifunctionality across region-wide environmental conditions.Mixed conifer-broadleaf tree plantations with distinct functional traits benefit the enhancement of ecosystem multifunctionality,and the magnitude of species mixture effects is modulated by the functional identity of tree species composition;those relationships deserve a special consideratio展开更多
Aims Positive biodiversity-ecosystem functioning relationships have been widely reported,predominately from grassland ecosystems.However,this does not necessarily have to apply accordingly in more complex situations s...Aims Positive biodiversity-ecosystem functioning relationships have been widely reported,predominately from grassland ecosystems.However,this does not necessarily have to apply accordingly in more complex situations such as in forests across different vertical strata.For instance,overstorey tree species richness has been shown to be associated with a lower understorey productivity.Whether or not tree species richness effects add to understorey productivity by increasing(i.e.due to habitat heterogeneity)or reducing resource availability(i.e.through increasing competition)and whether understorey productivity is indeed being governed more strongly by tree species identity are likely to change over time.Moreover,studies also suggested that richness-productivity relationships change with the environmental context.Using an experimental forest plantation with manipulated tree species richness,this study examined these temporal and environmental dynamics across strata.Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of understorey biomass samples repeatedly collected over a time period of 3 years along a tree species richness gradient.The effects of tree species richness,tree species identities and time were studied across different environmental treatments for their impact on understorey biomass.Important Findings While we found significant and consistent tree layer identity effects on understorey biomass,no such effect was encountered for tree species richness.Our results also indicate that among structural layers in forests,there might not be a single,generalizable overstorey species richness-understorey productivity relationship,and that the extent as to which overstorey-related environmental factors such as light transmittance contribute to understorey productivity change with time.Overall,we demonstrate that temporal dynamics should be considered when studying relationship among structural layers in forests.展开更多
Foliar fungal pathogens affect forest ecosystem processes by exerting highly species-specific impacts on growth and survival of trees.As many ecosystem processes in forests depend on functional diversity of specific t...Foliar fungal pathogens affect forest ecosystem processes by exerting highly species-specific impacts on growth and survival of trees.As many ecosystem processes in forests depend on functional diversity of specific tree species,a close relationship is expected between this and foliar fungal pathogen infestation.Testing for such a relationship in the German tree diversity experiment BIOTREE(Bechstedt),we hypothesized that pathogen richness and pathogen load decline with increasing functional diversity of tree communities.Using macro-and microscopic analyses,we assessed pathogen richness and load on 16 tree species in plots that,although differing in functional diversity,had the same tree species richness.We found no effects of functional diversity on pathogen richness or load.However,we encountered strong species identity effects in plot species composition,as susceptible tree species contributed positively to each community’s pathogen richness and load.Furthermore,testing for effects of particular leaf traits and geographical range size of host species revealed a significant effect of total leaf phenolics,which was unexpected as pathogen richness increased with increasing content in polyphenolics.Our study showed that at the community level,host species’identity was more important for foliar fungal pathogen richness and load than the functional diversity of host trees.The positive relationship between pathogen richness and phenolics in leaves,along with the finding that pathogen richness is very much conserved in tree species,point to an evolutionary arms race between hosts and fungi resulting from fungi increasing their capacity to infect tree leaves and trees boosting their defences.展开更多
基金supported by the National Natural Science Foundation of China(Nos.31670329,31470463,31500321,31770434)
文摘Wastewater with relatively high nitrogen concentrations is a major source of nitrous oxide(N_2O) and methane(CH_4) emissions and exerts multiple stresses on the environment.Studies have shown that plant diversity plays an important role in ecosystem functioning.However, the effects of plant species diversity on CH_4 and N_2O emissions under high ammonium(NH_4^+-N) loading rates remain unclear. In this study, a microcosm experiment simulating vertical constructed wetlands supplied with high NH_4^+-N water levels was established. The treatments included four species richness levels(1, 2, 3, 4) and 15 species compositions. There was no significant relationship between species richness and N_2O emissions. However, N_2O emissions were significantly reduced by specific plant species composition. Notably, the communities with the presence of Rumex japonicus L. reduced N_2O emissions by 62% compared to communities without this species. This reduction in N_2O emissions may have been a result of decreased N concentrations and increased plant biomass. CH_4 emissions did not respond to plant species richness or species identity.Overall, plant species identity surpassed species richness in lowering N_2O emissions from constructed wetlands with high NH_4^+-N water. The results also suggest that communities with R. japonicus could achieve higher N removal and lower greenhouse gas emissions than other wetland species.
基金funded by the National Natural Science Foundation of China (No. 31930078)the National Key Research and Development Program of China (No. 2021YFD2200405)
文摘Mixed-species plantations generally exhibit higher ecosystem multifunctionality than monospecific plantations.However,it is unclear how tree species functional composition influences species mixture effects on ecosystem multifunctionality.We selected 171 monospecific and mixed-species plantations from nine regions across subtropical China,and quantified 13 key ecosystem functional properties to investigate how species mixture effects on ecosystem multifunctionality are modulated by functional diversity and identity.We found that ecosystem multifunctionality was significantly higher(p<0.05)in mixed tree plantations than in monospecific plantations except the mixed-conifer species plantations.Across all regions,ecosystem multifunctionality was significantly higher(p<0.05)in mixed conifer-broadleaf plantations than in monospecific plantations of the corresponding species,but not different between mixed and monospecific coniferous plantations.The magnitude of species mixture effects on ecosystem multifunctionality varied greatly with tree species compositions.Taking Cunninghamia lanceolata Lamb.as an example,the effects varied from a range of 2.0%–9.6%when mixed with a conifer species to 36%–87%when mixed with a broadleaf species.The functional diversity was the dominate driver shaping ecosystem multifunctionality,while functional identity,as expressed by community-weighted mean of specific leaf area,also had a positive effect on ecosystem multifunctionality through the increased below-ground nitrogen and phosphorus stocks regulated by specific leaf area of the mixing tree species.Our study highlights the important role of functional diversity in shaping ecosystem multifunctionality across region-wide environmental conditions.Mixed conifer-broadleaf tree plantations with distinct functional traits benefit the enhancement of ecosystem multifunctionality,and the magnitude of species mixture effects is modulated by the functional identity of tree species composition;those relationships deserve a special consideratio
基金This work was supported by the German Research Foundation(DFG FOR 891/3)with a grant to A.E.(ER 573/1-3).
文摘Aims Positive biodiversity-ecosystem functioning relationships have been widely reported,predominately from grassland ecosystems.However,this does not necessarily have to apply accordingly in more complex situations such as in forests across different vertical strata.For instance,overstorey tree species richness has been shown to be associated with a lower understorey productivity.Whether or not tree species richness effects add to understorey productivity by increasing(i.e.due to habitat heterogeneity)or reducing resource availability(i.e.through increasing competition)and whether understorey productivity is indeed being governed more strongly by tree species identity are likely to change over time.Moreover,studies also suggested that richness-productivity relationships change with the environmental context.Using an experimental forest plantation with manipulated tree species richness,this study examined these temporal and environmental dynamics across strata.Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of understorey biomass samples repeatedly collected over a time period of 3 years along a tree species richness gradient.The effects of tree species richness,tree species identities and time were studied across different environmental treatments for their impact on understorey biomass.Important Findings While we found significant and consistent tree layer identity effects on understorey biomass,no such effect was encountered for tree species richness.Our results also indicate that among structural layers in forests,there might not be a single,generalizable overstorey species richness-understorey productivity relationship,and that the extent as to which overstorey-related environmental factors such as light transmittance contribute to understorey productivity change with time.Overall,we demonstrate that temporal dynamics should be considered when studying relationship among structural layers in forests.
基金The research leading to these results also attracted funding from the European Union’s Seventh Framework Programme(FP7/2007-2013)under grant agreement no265171,project FunDivEUROPE as well as of the BACCARA project,which received funding from the European Commission’s Seventh Framework Programme(FP7/2007-2013),under grant agreement no226299.O.P.and H.B.also acknowledge the support of the German Centre for Integrative Biodiversity Research(iDiv)HalleJena-Leipzig,funded by the German Science Foundation(FZT 118).
文摘Foliar fungal pathogens affect forest ecosystem processes by exerting highly species-specific impacts on growth and survival of trees.As many ecosystem processes in forests depend on functional diversity of specific tree species,a close relationship is expected between this and foliar fungal pathogen infestation.Testing for such a relationship in the German tree diversity experiment BIOTREE(Bechstedt),we hypothesized that pathogen richness and pathogen load decline with increasing functional diversity of tree communities.Using macro-and microscopic analyses,we assessed pathogen richness and load on 16 tree species in plots that,although differing in functional diversity,had the same tree species richness.We found no effects of functional diversity on pathogen richness or load.However,we encountered strong species identity effects in plot species composition,as susceptible tree species contributed positively to each community’s pathogen richness and load.Furthermore,testing for effects of particular leaf traits and geographical range size of host species revealed a significant effect of total leaf phenolics,which was unexpected as pathogen richness increased with increasing content in polyphenolics.Our study showed that at the community level,host species’identity was more important for foliar fungal pathogen richness and load than the functional diversity of host trees.The positive relationship between pathogen richness and phenolics in leaves,along with the finding that pathogen richness is very much conserved in tree species,point to an evolutionary arms race between hosts and fungi resulting from fungi increasing their capacity to infect tree leaves and trees boosting their defences.
