Trait-based analyses provide a mechanistic approach to understanding the processes driving the patterns in macroinvertebrate community structure. Whittaker (1975) described differences in taxonomic composition among assemblages as β-diversity. β-diversity may result from taxonomic turnover of ecologically different species over an environmental gradient, or turnover of ecologically similar species over a spatial gradient (Ackerly and Cornwell, 2007). The former indicates environmental filtering or biotic interactions drive local community assembly, and the latter indicates between-site variation is due to differences in source pools. Our objectives were to determine which traits were non-randomly sorted at each scale, and the spatial lag at which taxonomic turnover within an ecotype occurred. We assessed local patterns in macroinvertebrate community structure from four forested headwater streams in the Nantahala National Forest, and regional patterns from 26 watershed scale observations within the Blue Ridge physiographic province. The relationship between co-occurrence patterns and functional similarity among taxa were analyzed using partial mantel tests to determine the spatial lag at which taxonomic turnover occurred. Traits either exhibited taxonomic replacement at the local scale (<5km) or regional scale (>200km), suggesting the mechanisms driving community sorting depend on the grain size of observation and the extent of the study.