Partitioning of benthic biodiversity in boreal streams: Contributions of spatial, inter‐annual, and seasonal variability

Studies on biodiversity patterns should optimally relate different scales of temporal community variability to spatial variability. Although is often negligible compared variation, it may still constitute a substantial source overall in stream ecosystems. Boreal streams exhibit seasonally recurring environmental periodicity, which can be expected induce synchronous dynamics abiotic variables among sites, and consequently, produce synchrony deterministically controlled biological communities with higher intra- than inter-annual We sampled benthic macroinvertebrates 10 near-pristine boreal three seasons (spring, summer, autumn) across 4 consecutive years northern Finland. aimed identify the relative contributions spatial, inter-annual, seasonal biodiversity; variation invertebrate key factors, particularly in-stream habitat diversity. Among-site was clearly most important for both species richness dissimilarity. Of two scales, contributed more taxonomic slightly composition. Only differed systematically from random expectation, indicating strong stability (low variability) macroinvertebrate years, less at sites substrate heterogeneity. Considering distinct seasonality environment, accounted an unexpectedly low amount total differences between were small, autumnal sampling likely least susceptible climatic vagaries, thus providing consistent predictable conditions streams, bioassessment purposes. Exceptional are becoming frequent Europe, probably causing largely unpredictable changes As result, importance (relative spatial) increase.