The cosmopolitan calcifying alga Emiliania huxleyi is one of the most abundant bloom forming coccolithophore species in the oceans and plays an important role in global biogeochemical cycling. Coccolithoviruses are a ...The cosmopolitan calcifying alga Emiliania huxleyi is one of the most abundant bloom forming coccolithophore species in the oceans and plays an important role in global biogeochemical cycling. Coccolithoviruses are a major cause of coccolithophore bloom termination and have been studied in laboratory, mesocosm and open ocean studies. However, little is known about the dynamic interactions between the host and its viruses, and less is known about the natural diversity and role of functionally important genes within natural coccolithovirus communities. Here, we investigate the temporal and spatial distribution of coccolithoviruses by the use of molecular fingerprinting techniques PCR, DGGE and genomie sequencing. The natural biodiversity of the virus genes encoding the major capsid protein （MCP） and serine palmitoyltransferase （SPT） were analysed in samples obtained from the Atlantic Meridional Transect （AMT）, the North Sea and the L4 site in the Westem Channel Observatory. We discovered nine new coccolithovirus genotypes across the AMT and L4 site, with the majority of MCP sequences observed at the deep chlorophyll maximum layer of the sampled sites on the transect. We also found four new SPT gene variations in the North Sea and at L4. Their translated fragments and the full protein sequence of SPT from laboratory strains EhV-86 and EhV-99B 1 were modelled and revealed that the theoretical fold differs among strains. Variation identified in the structural distance between the two domains of the SPT protein may have an impact on the catalytic capabilities of its active site. In summary, the combined use of ＇standard＇ markers （i.e. MCP）, in combination with metabolically relevant markers （i.e. SPT） are useful in the study of the phylogeny and functional biodiversity of coccolithoviruses, and can provide an interesting intracellular insight into the evolution of these viruses and their ability to infect and replicate within their algal hosts.展开更多
Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although m...Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although many hypotheses have been developed to interpret global gradients of biodiversity, there has not been complete agreement on mechanisms controlling biodiversity patterns and distributions. Differences may be due to limited observation data and inconsistencies of spatial scales in analysis. Methods： In this study, we take advantage of USDA Forest Service forest inventory and analysis （FIA） data for exploring regional forest biodiversity and BEF in New England forests. The FIA data provide detailed information of sampled plots and trees for the region, including 6000 FIA plots and more than 33,000 individual trees. Biodiversity models were used to analyze the data. Results： Tree species diversity increases from the north to the south at a rate about 2-3 species per latitudinal degree. Tree species diversity is better predicted by tree height than forest age or biomass. Very different distribution patterns of two common maple species, sugar maple （Acer sdcchorum） and red maple （Acer rubrum）, highlight the vulnerability of sugar maple and its potential replacement by red maple on New England landscapes. Red maple generally already outperforms sugar maple, and will likely and continuously benefit from a changing climate in New England. Conclusions： We conclude that forest structure （height） and resources （biomass） are more likely foundational characteristics supporting biodiversity rather than biodiversity determining forest productivity and/or biomass. The potential replacement of red maple for sugar maple in the New England areas could affect biodiversity and stability of forest ecosystem functioning because sugar maple plays important ecological roles distinct from red maple that are beneficial to other tree species in northern hardwood forests. Such a change may not affect forest resilience in terms of forest productivity and biomass as these are similar in red maple and sugar maple, however, it would almost certainly alter forest structure across the landscape.展开更多
Background:Anthropogenic disturbances are increasingly affecting the vitality of tropical dry forests.The future condition of this important biome will depend on its capability to resist and recover from these disturb...Background:Anthropogenic disturbances are increasingly affecting the vitality of tropical dry forests.The future condition of this important biome will depend on its capability to resist and recover from these disturbances.So far,the temporal stability of dryland forests is rarely studied,even though identifying the important factors associated with the stability of the dryland forests could serve as a basis for forest management and restoration.Methodology:In a degraded dry Afromontane forest in northern Ethiopia,we explored remote sensing derived indicators of forest stability,using MODIS satellite derived NDVI time series from 2001 to 2018.Resilience and resistance were measured using the anomalies(remainders)after time series decomposition into seasonality,trend and remainder components.Growth stability was calculated using the integral of the undecomposed NDVI data.These NDVI derived stability indicators were then related to environmental factors of climate,topography,soil,tree species diversity,and local human disturbance,obtained from a systematic grid of field inventory plots,using boosted regression trees in R.Results:Resilience and resistance were adequately predicted by these factors with an R^(2) of 0.67 and 0.48,respectively,but the model for growth stability was weaker.Precipitation of the wettest month,distance from settlements and slope were the most important factors associated with resilience,explaining 51%of the effect.Altitude,temperature seasonality and humus accumulation were the significant factors associated with the resistance of the forest,explaining 61%of the overall effect.A positive effect of tree diversity on resilience was also important,except that the impact of species evenness declined above a threshold value of 0.70,indicating that perfect evenness reduced the resilience of the forest.Precipitation of the wettest month was the most important factor explaining 43.52%of the growth stability variation.Conclusion:A combination of climate,topographic factors and local human disturbance controlled the stability of the dry forest.Also tree diversity is an important stability component that should be considered in the management and restoration programs of such degraded forests.If local disturbances are alleviated the recovery time of dryland forests could be shortened,which is vital to maintain the ecosystem services these forests provide to local communities and global climate change.展开更多
Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open...Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species （Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber） in the Gutianshan （古田山） National Nature Reserve （GNNR）. The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches （drips） are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species （deciduous, evergreen） revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.展开更多
Biodiversity is found to have a significant promotion effect on ecosystem functions in manipulation experiments on grassland communities.However,its relative role compared with stand factors or functional identity is ...Biodiversity is found to have a significant promotion effect on ecosystem functions in manipulation experiments on grassland communities.However,its relative role compared with stand factors or functional identity is still controversial in natural forests.Here,we examined their relative effects on biomass and productivity during forest restoration.We investigated stand biomass and productivity for 24 plots(600 m2)across restoration stages in the subtropical forests of Mt.Shennongjia,Central China.We measured five key functional traits and calculated functional diversity(functional richness,evenness and dispersion)and community-weighted mean of traits.We used general linear models,variation partitioning methods to test the relative importance of stand factors(density,stand age,maximum height,etc.),functional identity,species and functional diversity on biomass and productivity.Our results illustrated that stand biomass and productivity increased significantly as forest restoration,and that community species richness increased,while functional dispersion decreased significantly.Variation partitioning analyses showed that diversity had no significant pure effects on biomass and productivity.However,diversity may affect biomass and productivity through the joint effect with stand factors and functional identity.Overall,we found that stand factors had the strongest effect on biomass and productivity,while functional identity significantly affects productivity but not biomass,suggesting that modulating stand structure and species identity are effective ways to enhance forest carbon storage and sequestrations potential in forest management.展开更多
Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diver...Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment(as of2018) in Japan.Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages(≤ 3 years), the positive complementarity effect was explained by enhanced growths of early-and mid-successional species in the mixture. Later on(≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer.Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.展开更多
A positive biodiversity-ecosystem functioning(BEF)relationship is frequently reported for biotic communities with low diversity levels.However,whether this is also true for highly diverse soil microbial communities re...A positive biodiversity-ecosystem functioning(BEF)relationship is frequently reported for biotic communities with low diversity levels.However,whether this is also true for highly diverse soil microbial communities remains unclear.The study explored the BEF relationships between species richness and nitrogen(N)-transforming capability of nirK-and nirS-nitrite reducers,nitrous oxide reducers,and nitrite oxidizer communities in soils from five different vegetation types.The results consistently indicated negative BEF patterns in these N-transforming microbes.The relative abundance of keystone taxa from co-occurrence networks increased substantially with species richness but was negatively correlated with functional performance.Network complexity decreased in communities with high species richness.These findings suggest that negative selection and biotic competition may simultaneously generate negative BEF patterns.A conceptual model was also proposed in which the BEF relationship followed a quadratic curve that varied with the level of diversity.Microbial diversity is crucial for maintaining the balance of ecological systems because microorganisms play key roles in nutrient cycling and other essential biogeochemical processes.Recent studies have shown that increased diversity may not always lead to improved ecosystem function.The current study indicated that function decreased with species richness in soil Ntransforming bacterial communities.Keystone taxa were positively correlated with species richness but negatively correlated with function.Community complexity decreased with increasing species richness.These findings suggest that both negative selection effects and biotic competition may simultaneously generate negative biodiversity-ecosystem functional relationships.展开更多
Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our o...Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.Methods We measured tree height of 2493 living individuals in 57 plots and specific root length(SRL)on first-order roots of 368 of these individuals across different species richness levels(1,2,4,8 species)in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China(BEF-China)established in 2009.We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity(RaoQ)and further effects of species interactions by variable components of interspecific and intraspecific functional diversity(community weighted trait similarity and trait dissimilarity,CWS and CWD).Finally,we examined the relationships between biodiversity effects on stand-level tree height and functional diversity(RaoQ,CWS and CWD)in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.Important Findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species.A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL.A positive CE was related to high values of all three components of root functional diversity(RaoQ,CWS and CWD).Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.展开更多
Natural native forests are rapidly being replaced by anthropogenic forests often with a strong presence of invasive alien plant species.Eucalypt species are widely planted worldwide,with Eucalyptus globulus plantation...Natural native forests are rapidly being replaced by anthropogenic forests often with a strong presence of invasive alien plant species.Eucalypt species are widely planted worldwide,with Eucalyptus globulus plantations being par-ticularly expressive in Portugal.Poor forestry practices often lead to the associated expansion of invasive species,such as Acacia dealbata.However,we still know relatively little about the functioning of anthropogenic forests,such as seed and pollen dispersal services.Here,we compared bird abundance and richness and the seed and pollen dispersal networks in both forest types.Anthropogenic forests presented lower bird abundance,and smaller,more simplified,and more random(abundance-based)seed dispersal services than those of natural forests.Interestingly,the pollen dispersal network was more similar than the seed dispersal network for both forest types and domi-nated by opportunistic and neutral processes,given the absence of specialized nectarivorous.The proportion of birds transporting seeds decreased,while those carrying pollen significantly increased in the anthropogenic forest compared to the native forest.Our work highlights the impact of anthropogenic forests on bird abundance,with consequences for seed dispersal services and forest regeneration.展开更多
Aims In forests,the herbaceous understory vegetation plays an important role for ecosystem functioning as it represents a significant component of total aboveground productivity.In addition,the herb layer contributes ...Aims In forests,the herbaceous understory vegetation plays an important role for ecosystem functioning as it represents a significant component of total aboveground productivity.In addition,the herb layer contributes to overall forest species richness and controls tree species regeneration.Vice versa,trees in the overstory control understory herb and shrub growth through competition for resources.Using an experimental forest plantation with manipulated tree richness,we asked to which degree tree species richness and identity affect herb layer composition,richness and productivity and how these relationships across strata change with abiotic environmental conditions and competition intensity.Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of the integrated BEFmod experiment arranged along a tree species richness gradient at two sites,with additional subplot treatments of phosphorus addition,herb layer weeding and no weeding.We recorded the understory vegetation and determined herb layer biomass production on a total of 201 subplots.Important Findings We found only minor effects of tree layer richness on herb layer species composition and no significant effect on herb layer richness or productivity yet.However,there were strong tree layer identity effects on all response variables,which were partly explained by differences in leaf area index and by a high share of woody species both in total herb layer species richness and biomass.There were strong treatment effects,which were largest in the‘no weeding’treatment but we did not find any treatment×tree layer richness interaction in herb layer responses.Thus,these effects are mainly explained by increased competition intensity within the herb layer in the absence of weeding.Despite the young age of the experiment,the interactions between tree species identity,tree richness and the herb layer did already emerge and can be expected to become stronger with ongoing runtime of the experiment.展开更多
Background:More frequent and severe drought events due to climate change pose a major challenge for sustainable forage production in managed grasslands.This study investigated whether multispecies grassland communitie...Background:More frequent and severe drought events due to climate change pose a major challenge for sustainable forage production in managed grasslands.This study investigated whether multispecies grassland communities can provide greater resistance to and/or recovery from drought compared to monoculture communities.Methods:Mesocosms of Lolium perenne L.,Cichorium intybus L.,Trifolium repens L.and Trifolium pratense L.were established as monocultures,and a four-species mixture.A drought gradient with five levels of water supply ranging from a mild to a severe treatment was applied for 10 weeks,in each of 2 years.Shoot biomass was harvested to assess drought resistance,drought recovery and annual yields.Root mass density and specific root length were measured in Year 2.Results:Across the drought gradient,four-species communities had significantly larger annual yields than each of the four monocultures,indicating transgressive overyielding.This was despite relatively low drought resistance for four-species communities compared with L.perenne and C.intybus monocultures.Recovery of yields following drought was high for all communities.Conclusions:Multispecies swards with complementary traits can provide a viable adaptation option across a wide range of drought severities.Application of a stress gradient methodology allowed a more detailed understanding of stress responses.展开更多
文摘The cosmopolitan calcifying alga Emiliania huxleyi is one of the most abundant bloom forming coccolithophore species in the oceans and plays an important role in global biogeochemical cycling. Coccolithoviruses are a major cause of coccolithophore bloom termination and have been studied in laboratory, mesocosm and open ocean studies. However, little is known about the dynamic interactions between the host and its viruses, and less is known about the natural diversity and role of functionally important genes within natural coccolithovirus communities. Here, we investigate the temporal and spatial distribution of coccolithoviruses by the use of molecular fingerprinting techniques PCR, DGGE and genomie sequencing. The natural biodiversity of the virus genes encoding the major capsid protein （MCP） and serine palmitoyltransferase （SPT） were analysed in samples obtained from the Atlantic Meridional Transect （AMT）, the North Sea and the L4 site in the Westem Channel Observatory. We discovered nine new coccolithovirus genotypes across the AMT and L4 site, with the majority of MCP sequences observed at the deep chlorophyll maximum layer of the sampled sites on the transect. We also found four new SPT gene variations in the North Sea and at L4. Their translated fragments and the full protein sequence of SPT from laboratory strains EhV-86 and EhV-99B 1 were modelled and revealed that the theoretical fold differs among strains. Variation identified in the structural distance between the two domains of the SPT protein may have an impact on the catalytic capabilities of its active site. In summary, the combined use of ＇standard＇ markers （i.e. MCP）, in combination with metabolically relevant markers （i.e. SPT） are useful in the study of the phylogeny and functional biodiversity of coccolithoviruses, and can provide an interesting intracellular insight into the evolution of these viruses and their ability to infect and replicate within their algal hosts.
基金the project NRS-6“Climate,Fire,and Carbon Cycle Sciences”supported by the USDA Forest ServiceBeijing Forestry University for covering the trip to the conference and generous conference venue facilitating this study
文摘Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although many hypotheses have been developed to interpret global gradients of biodiversity, there has not been complete agreement on mechanisms controlling biodiversity patterns and distributions. Differences may be due to limited observation data and inconsistencies of spatial scales in analysis. Methods： In this study, we take advantage of USDA Forest Service forest inventory and analysis （FIA） data for exploring regional forest biodiversity and BEF in New England forests. The FIA data provide detailed information of sampled plots and trees for the region, including 6000 FIA plots and more than 33,000 individual trees. Biodiversity models were used to analyze the data. Results： Tree species diversity increases from the north to the south at a rate about 2-3 species per latitudinal degree. Tree species diversity is better predicted by tree height than forest age or biomass. Very different distribution patterns of two common maple species, sugar maple （Acer sdcchorum） and red maple （Acer rubrum）, highlight the vulnerability of sugar maple and its potential replacement by red maple on New England landscapes. Red maple generally already outperforms sugar maple, and will likely and continuously benefit from a changing climate in New England. Conclusions： We conclude that forest structure （height） and resources （biomass） are more likely foundational characteristics supporting biodiversity rather than biodiversity determining forest productivity and/or biomass. The potential replacement of red maple for sugar maple in the New England areas could affect biodiversity and stability of forest ecosystem functioning because sugar maple plays important ecological roles distinct from red maple that are beneficial to other tree species in northern hardwood forests. Such a change may not affect forest resilience in terms of forest productivity and biomass as these are similar in red maple and sugar maple, however, it would almost certainly alter forest structure across the landscape.
基金PhD IRO grant from KU Leuven and We Forest Ethiopia supported the data collection.It is one of the chapters of a PhD research and there is no specific ID attached to the funds。
文摘Background:Anthropogenic disturbances are increasingly affecting the vitality of tropical dry forests.The future condition of this important biome will depend on its capability to resist and recover from these disturbances.So far,the temporal stability of dryland forests is rarely studied,even though identifying the important factors associated with the stability of the dryland forests could serve as a basis for forest management and restoration.Methodology:In a degraded dry Afromontane forest in northern Ethiopia,we explored remote sensing derived indicators of forest stability,using MODIS satellite derived NDVI time series from 2001 to 2018.Resilience and resistance were measured using the anomalies(remainders)after time series decomposition into seasonality,trend and remainder components.Growth stability was calculated using the integral of the undecomposed NDVI data.These NDVI derived stability indicators were then related to environmental factors of climate,topography,soil,tree species diversity,and local human disturbance,obtained from a systematic grid of field inventory plots,using boosted regression trees in R.Results:Resilience and resistance were adequately predicted by these factors with an R^(2) of 0.67 and 0.48,respectively,but the model for growth stability was weaker.Precipitation of the wettest month,distance from settlements and slope were the most important factors associated with resilience,explaining 51%of the effect.Altitude,temperature seasonality and humus accumulation were the significant factors associated with the resistance of the forest,explaining 61%of the overall effect.A positive effect of tree diversity on resilience was also important,except that the impact of species evenness declined above a threshold value of 0.70,indicating that perfect evenness reduced the resilience of the forest.Precipitation of the wettest month was the most important factor explaining 43.52%of the growth stability variation.Conclusion:A combination of climate,topographic factors and local human disturbance controlled the stability of the dry forest.Also tree diversity is an important stability component that should be considered in the management and restoration programs of such degraded forests.If local disturbances are alleviated the recovery time of dryland forests could be shortened,which is vital to maintain the ecosystem services these forests provide to local communities and global climate change.
基金supported by the Deutsche Forschungsgemein-schaft (German Science Foundation) (No. DFG FOR 891/1)the National Natural Science Foundation of China (Nos. 30710103907, 30930005)
文摘Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species （Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber） in the Gutianshan （古田山） National Nature Reserve （GNNR）. The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches （drips） are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species （deciduous, evergreen） revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.
基金supported by the National Natural Science Foundation of China(31870430)the National Key Research and Development Program of China(2017YFC0503901,2016YFC0502104).
文摘Biodiversity is found to have a significant promotion effect on ecosystem functions in manipulation experiments on grassland communities.However,its relative role compared with stand factors or functional identity is still controversial in natural forests.Here,we examined their relative effects on biomass and productivity during forest restoration.We investigated stand biomass and productivity for 24 plots(600 m2)across restoration stages in the subtropical forests of Mt.Shennongjia,Central China.We measured five key functional traits and calculated functional diversity(functional richness,evenness and dispersion)and community-weighted mean of traits.We used general linear models,variation partitioning methods to test the relative importance of stand factors(density,stand age,maximum height,etc.),functional identity,species and functional diversity on biomass and productivity.Our results illustrated that stand biomass and productivity increased significantly as forest restoration,and that community species richness increased,while functional dispersion decreased significantly.Variation partitioning analyses showed that diversity had no significant pure effects on biomass and productivity.However,diversity may affect biomass and productivity through the joint effect with stand factors and functional identity.Overall,we found that stand factors had the strongest effect on biomass and productivity,while functional identity significantly affects productivity but not biomass,suggesting that modulating stand structure and species identity are effective ways to enhance forest carbon storage and sequestrations potential in forest management.
基金a Grant-in-Aid for Young Scientists B (No. 16 K18715)a JSPS Overseas Research Fellowship (No. 201860500) from the Japan Society for the Promotion of Science。
文摘Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment(as of2018) in Japan.Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages(≤ 3 years), the positive complementarity effect was explained by enhanced growths of early-and mid-successional species in the mixture. Later on(≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer.Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.
基金supported by the Central Public-Interest Scientific Institution Basal Research Fund(Grant No.CAFYBB2019QB001)the National Key R&D Fund(Grant No.2023YFF130440302)the Natural Science Foundation of China(Grant No.31870099).
文摘A positive biodiversity-ecosystem functioning(BEF)relationship is frequently reported for biotic communities with low diversity levels.However,whether this is also true for highly diverse soil microbial communities remains unclear.The study explored the BEF relationships between species richness and nitrogen(N)-transforming capability of nirK-and nirS-nitrite reducers,nitrous oxide reducers,and nitrite oxidizer communities in soils from five different vegetation types.The results consistently indicated negative BEF patterns in these N-transforming microbes.The relative abundance of keystone taxa from co-occurrence networks increased substantially with species richness but was negatively correlated with functional performance.Network complexity decreased in communities with high species richness.These findings suggest that negative selection and biotic competition may simultaneously generate negative BEF patterns.A conceptual model was also proposed in which the BEF relationship followed a quadratic curve that varied with the level of diversity.Microbial diversity is crucial for maintaining the balance of ecological systems because microorganisms play key roles in nutrient cycling and other essential biogeochemical processes.Recent studies have shown that increased diversity may not always lead to improved ecosystem function.The current study indicated that function decreased with species richness in soil Ntransforming bacterial communities.Keystone taxa were positively correlated with species richness but negatively correlated with function.Community complexity decreased with increasing species richness.These findings suggest that both negative selection effects and biotic competition may simultaneously generate negative biodiversity-ecosystem functional relationships.
基金funded by the National Natural Science Foundation of China(No.31300353)China Postdoctoral Science Foundation(No.2014M561089)+4 种基金Science and Technology Planning Project of Jiangxi Provincial Education Department(No.GJJ150384)the entire BEF-China research group for their supportfunded by the German Research Foundation(DFG FOR891)National Natural Science Foundation of China(NSFC)the Swiss National Science Foundation(SNSF).
文摘Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.Methods We measured tree height of 2493 living individuals in 57 plots and specific root length(SRL)on first-order roots of 368 of these individuals across different species richness levels(1,2,4,8 species)in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China(BEF-China)established in 2009.We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity(RaoQ)and further effects of species interactions by variable components of interspecific and intraspecific functional diversity(community weighted trait similarity and trait dissimilarity,CWS and CWD).Finally,we examined the relationships between biodiversity effects on stand-level tree height and functional diversity(RaoQ,CWS and CWD)in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.Important Findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species.A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL.A positive CE was related to high values of all three components of root functional diversity(RaoQ,CWS and CWD).Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.
基金support from the Portuguese Foundation for Science and Technology(FCT/MEC)via the grant SFRH/BD/77746/2011 and the individual research contract CEECIND/02064/2017/CP1423/CP1645/CT0009(https://doi.org/10.54499/CEECIND/02064/2017/CP1423/CP1645/CT0009)funded by(FCT/MEC)through grant UIDB/04004/2020.
文摘Natural native forests are rapidly being replaced by anthropogenic forests often with a strong presence of invasive alien plant species.Eucalypt species are widely planted worldwide,with Eucalyptus globulus plantations being par-ticularly expressive in Portugal.Poor forestry practices often lead to the associated expansion of invasive species,such as Acacia dealbata.However,we still know relatively little about the functioning of anthropogenic forests,such as seed and pollen dispersal services.Here,we compared bird abundance and richness and the seed and pollen dispersal networks in both forest types.Anthropogenic forests presented lower bird abundance,and smaller,more simplified,and more random(abundance-based)seed dispersal services than those of natural forests.Interestingly,the pollen dispersal network was more similar than the seed dispersal network for both forest types and domi-nated by opportunistic and neutral processes,given the absence of specialized nectarivorous.The proportion of birds transporting seeds decreased,while those carrying pollen significantly increased in the anthropogenic forest compared to the native forest.Our work highlights the impact of anthropogenic forests on bird abundance,with consequences for seed dispersal services and forest regeneration.
基金the coordination team of the BEF-China project for their supportthe support of M.S.G.from the German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig funded by the German Research Foundation(FZT 118)+1 种基金the Sino-German Centre for Research Promotion for the participation of M.S.G.in a Summer School in Jingdezhen(GZ 1146)funded by the German Research Foundation(DFG FOR 891/3)with a grant to A.E.(ER 573/1-3).
文摘Aims In forests,the herbaceous understory vegetation plays an important role for ecosystem functioning as it represents a significant component of total aboveground productivity.In addition,the herb layer contributes to overall forest species richness and controls tree species regeneration.Vice versa,trees in the overstory control understory herb and shrub growth through competition for resources.Using an experimental forest plantation with manipulated tree richness,we asked to which degree tree species richness and identity affect herb layer composition,richness and productivity and how these relationships across strata change with abiotic environmental conditions and competition intensity.Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of the integrated BEFmod experiment arranged along a tree species richness gradient at two sites,with additional subplot treatments of phosphorus addition,herb layer weeding and no weeding.We recorded the understory vegetation and determined herb layer biomass production on a total of 201 subplots.Important Findings We found only minor effects of tree layer richness on herb layer species composition and no significant effect on herb layer richness or productivity yet.However,there were strong tree layer identity effects on all response variables,which were partly explained by differences in leaf area index and by a high share of woody species both in total herb layer species richness and biomass.There were strong treatment effects,which were largest in the‘no weeding’treatment but we did not find any treatment×tree layer richness interaction in herb layer responses.Thus,these effects are mainly explained by increased competition intensity within the herb layer in the absence of weeding.Despite the young age of the experiment,the interactions between tree species identity,tree richness and the herb layer did already emerge and can be expected to become stronger with ongoing runtime of the experiment.
基金FP7 Food,Agriculture and Fisheries,Biotechnology,Grant/Award Number:266018。
文摘Background:More frequent and severe drought events due to climate change pose a major challenge for sustainable forage production in managed grasslands.This study investigated whether multispecies grassland communities can provide greater resistance to and/or recovery from drought compared to monoculture communities.Methods:Mesocosms of Lolium perenne L.,Cichorium intybus L.,Trifolium repens L.and Trifolium pratense L.were established as monocultures,and a four-species mixture.A drought gradient with five levels of water supply ranging from a mild to a severe treatment was applied for 10 weeks,in each of 2 years.Shoot biomass was harvested to assess drought resistance,drought recovery and annual yields.Root mass density and specific root length were measured in Year 2.Results:Across the drought gradient,four-species communities had significantly larger annual yields than each of the four monocultures,indicating transgressive overyielding.This was despite relatively low drought resistance for four-species communities compared with L.perenne and C.intybus monocultures.Recovery of yields following drought was high for all communities.Conclusions:Multispecies swards with complementary traits can provide a viable adaptation option across a wide range of drought severities.Application of a stress gradient methodology allowed a more detailed understanding of stress responses.
