Patterns and drivers of stream benthic macroinvertebrate beta diversity in an agricultural landscape.

Knowledge of benthic macroinvertebrate β-diversity patterns and drivers in an agricultural landscape can inform and improve watershed management decisions. Our study used multi-site and pairwise measures to determine taxonomic and functional β-diversity and associated nestedness and turnover components for benthic macroinvertebrate communities in the agricultural landscape. Total taxonomic β-diversity was mostly due to turnover, whereas total functional β-diversity was composed of turnover and nestedness more equally. Variation partitioning showed that spatial and habitat variables explained the largest proportion of variation in the total and turnover component of both taxonomic and functional β-diversity. Variation in nestedness was associated with local-scale habitat. Agricultural land cover was not a driver of β-diversity; however, extensive agricultural land cover appeared to disrupt the habitat–functional β-diversity relationship. Our findings suggest that distance among benthic macroinvertebrate communities should be considered when making land management or conservation decisions. Moreover, apparent disruption of the habitat–functional β-diversity relationship with extensive agricultural cover suggests managers should strategically target restoration activities to upland or channel areas based on catchment conditions. Finally, differences between taxonomic and functional β-diversity suggest including both measures in monitoring programs may enhance regional biodiversity assessments. [ABSTRACT FROM AUTHOR]