Background The global freshwater biodiversity crisis has led to widespread implementation of measures to counteract environmental degradation and biodiversity loss.While these efforts aim to foster recovery,intensifyi...Background The global freshwater biodiversity crisis has led to widespread implementation of measures to counteract environmental degradation and biodiversity loss.While these efforts aim to foster recovery,intensifying stressors continue to drive complex biotic responses,the trajectories and drivers of which are insufficiently understood.This study examines the roles of abiotic stressors,biotic interactions(e.g.,competition),and land use in shaping ecological status changes across Germany,using data from 1599 river sites sampled at least twice between 2004 and 2022.Results Changes in abiotic stressors emerged as the most consistent drivers of ecological status,explaining substantial variation(R^(2)=0.39)and similar slopes for recovery(β=-0.11)and degradation(β=-0.10).Biotic interactions,particularly interspecific competition,also influenced the ecological status(R^(2)=0.11),with stronger positive effects observed during recovery(β=2.99)compared to degradation(β=1.59).Land use effects varied by context:Streams in catchments with higher cropland or urban areas showed greater likelihood of recovery,whereas streams in forested catchments were more prone to degradation.These results highlight the interplay of abiotic and biotic factors in driving ecological processes of recovery and degradation.Conclusion These findings emphasize the critical role of improving water quality for enhancing biodiversity and ecological status in rivers,while also demonstrating the importance of biotic interactions and land use context in driving recovery dynamics.Integrating these insights into management and restoration efforts can enhance freshwater ecosystem resilience in the face of escalating environmental pressures.展开更多
Background Understanding the temporal development of community assembly processes is essential for assessing the recovery of degraded ecosystems after restoration.Community development in restored streams is often slo...Background Understanding the temporal development of community assembly processes is essential for assessing the recovery of degraded ecosystems after restoration.Community development in restored streams is often slow or absent,due to inadequate restoration,catchment-scale pressures,and/or colonisation barriers.Recovery processes involve three key filters:dispersal,environmental conditions and biotic interactions.Dispersal is critical for initial colonisation,while environmental conditions influence successful population establishment.Lastly,as available niches fill,biotic interactions,such as competition,gain importance.Despite the presence of many theories on how these three filters interact during community assembly,they have rarely been investigated simultaneously.Our detailed species-and site-specific approach allowed us to analyse the three filters in a hierarchical analysis.We assessed the effect of the three filters,by examining benthic invertebrate communities at 20 sites in the Boye catchment(Western Germany).The Boye and most of its tributaries were used as open sewers for a century,i.e.they were concrete channels transporting untreated sewage before gradual restoration was started in the 1990s.The bank reinforcements and concrete beds were removed,while riparian vegetation was left to natural succession.Accordingly,the sites were grouped as'unimpacted','recently restored'(<4 years),and'mature restored'(>10 years).An additional 28 sites provided information on distances to source populations,while the species'habitat suitability assessed environmental filtering.Biotic(interaction)filtering was evaluated through trait overlap analysis.Results Communities at recently restored sites differed from mature and unimpacted sites,while mature sites resembled unimpacted ones.Taxa at recently restored sites had nearer source populations,while those at mature and unimpacted sites better matched present habitats.Trait overlap did not differ between present and absent taxa.Conclusions Our results indicate that dispersal was essential in early recovery stages,with mass effects from upstream sources supporting taxa found at recently restored sites despite low habitat suitability.Over time,habitat suitability became more influential,shaping mature communities.Competition appeared relatively unimportant,yet competitive exclusion may explain small proportions of absent taxa at mature and recently restored sites.Hence,to effectively support stream recovery,it is essential to consider how different filtering processes operate at various stages of the recovery process.For example,mature communities could further develop if habitat availability increases,while the connectivity to source populations would only play a minor role.展开更多
基金funded by the Deutsche Forschungsgemeinschaft(DFG,German Research FoundationCRC 1439/1,project number:426547801)
文摘Background The global freshwater biodiversity crisis has led to widespread implementation of measures to counteract environmental degradation and biodiversity loss.While these efforts aim to foster recovery,intensifying stressors continue to drive complex biotic responses,the trajectories and drivers of which are insufficiently understood.This study examines the roles of abiotic stressors,biotic interactions(e.g.,competition),and land use in shaping ecological status changes across Germany,using data from 1599 river sites sampled at least twice between 2004 and 2022.Results Changes in abiotic stressors emerged as the most consistent drivers of ecological status,explaining substantial variation(R^(2)=0.39)and similar slopes for recovery(β=-0.11)and degradation(β=-0.10).Biotic interactions,particularly interspecific competition,also influenced the ecological status(R^(2)=0.11),with stronger positive effects observed during recovery(β=2.99)compared to degradation(β=1.59).Land use effects varied by context:Streams in catchments with higher cropland or urban areas showed greater likelihood of recovery,whereas streams in forested catchments were more prone to degradation.These results highlight the interplay of abiotic and biotic factors in driving ecological processes of recovery and degradation.Conclusion These findings emphasize the critical role of improving water quality for enhancing biodiversity and ecological status in rivers,while also demonstrating the importance of biotic interactions and land use context in driving recovery dynamics.Integrating these insights into management and restoration efforts can enhance freshwater ecosystem resilience in the face of escalating environmental pressures.
基金the CRC RESIST,which was funded by the German Research Foundation(Deutsche Forschungsgemeinschaft,DFG)–CRC 1439–project number:426547801
文摘Background Understanding the temporal development of community assembly processes is essential for assessing the recovery of degraded ecosystems after restoration.Community development in restored streams is often slow or absent,due to inadequate restoration,catchment-scale pressures,and/or colonisation barriers.Recovery processes involve three key filters:dispersal,environmental conditions and biotic interactions.Dispersal is critical for initial colonisation,while environmental conditions influence successful population establishment.Lastly,as available niches fill,biotic interactions,such as competition,gain importance.Despite the presence of many theories on how these three filters interact during community assembly,they have rarely been investigated simultaneously.Our detailed species-and site-specific approach allowed us to analyse the three filters in a hierarchical analysis.We assessed the effect of the three filters,by examining benthic invertebrate communities at 20 sites in the Boye catchment(Western Germany).The Boye and most of its tributaries were used as open sewers for a century,i.e.they were concrete channels transporting untreated sewage before gradual restoration was started in the 1990s.The bank reinforcements and concrete beds were removed,while riparian vegetation was left to natural succession.Accordingly,the sites were grouped as'unimpacted','recently restored'(<4 years),and'mature restored'(>10 years).An additional 28 sites provided information on distances to source populations,while the species'habitat suitability assessed environmental filtering.Biotic(interaction)filtering was evaluated through trait overlap analysis.Results Communities at recently restored sites differed from mature and unimpacted sites,while mature sites resembled unimpacted ones.Taxa at recently restored sites had nearer source populations,while those at mature and unimpacted sites better matched present habitats.Trait overlap did not differ between present and absent taxa.Conclusions Our results indicate that dispersal was essential in early recovery stages,with mass effects from upstream sources supporting taxa found at recently restored sites despite low habitat suitability.Over time,habitat suitability became more influential,shaping mature communities.Competition appeared relatively unimportant,yet competitive exclusion may explain small proportions of absent taxa at mature and recently restored sites.Hence,to effectively support stream recovery,it is essential to consider how different filtering processes operate at various stages of the recovery process.For example,mature communities could further develop if habitat availability increases,while the connectivity to source populations would only play a minor role.
