ABSTRACT Many perennial streams in Central Europe have become intermittent due to climate change and human pressures. The loss of surface water has a dramatic impact on freshwater biota. Species inhabiting intermittent streams must exhibit particular life‐history strategies to survive dry periods. Riparian vegetation forms the interface between terrestrial and aquatic ecosystems and strongly influences key stream processes. Specific environmental variables, critical for survival in a dry streambed (e.g., temperature, substrate permeability), may be affected by the presence of vegetated riparian buffer strips in modified landscapes. The variable distribution of woody vegetation in modified catchments led us to investigate the effects of riparian buffer strips on ecosystem structure of intermittent streams. We hypothesised that woody riparian vegetation would stabilise temperature regimes, reduce nutrient and fine sediment inputs and mitigate the impacts of stream drying on benthic diatoms and macroinvertebrate communities. Streams with riparian vegetation had lower water temperatures, lower total phosphorus concentrations, and higher dissolved oxygen concentrations. Unvegetated streams were exposed to higher solar radiation, had larger areas of macrophytes in their streambeds, and the streambed substratum was more clogged by fine sediment. Benthic diatom communities from vegetated and unvegetated streams did not differ. In contrast, macroinvertebrate assemblages displayed distinct differences, with shifts in the composition of functional traits reflecting changes in abiotic conditions. In streams with well‐developed riparian vegetation, taxonomic richness was higher and there was a higher proportion of grazers and taxa sensitive to fine sediment. In streams without riparian vegetation, there was a higher proportion of eurytherms and invertebrate taxa preferring slow currents. In general, vegetated streams hosted more sensitive communities. However, contrary to our expectations, riparian vegetation was not associated with a lower response of macroinvertebrate diversity to stream drying. The presence of woody riparian vegetation significantly altered key environmental properties and benthic invertebrate community structure, resulting in multiple positive effects on streams in our study. However, taxonomically more diverse communities from vegetated streams were more sensitive to direct drought impact, and the immediate impact of stream drying was stronger there. Despite not proving that woody riparian vegetation can mitigate stream drying, we encourage their use as a practical management action to improve invertebrate biodiversity and stream ecosystem functioning.
Straka et al. (Wed,) studied this question.