Ecological and geomorphic theory assume longitudinal connectivity; we test whether these concepts apply in a naturally disconnected stream network with mainstem lakes and coarse glacial legacy sediment. We determined downstream hydraulic geometry relationships for channel width and inventoried riparian vegetation in each new process-domain (rapids, slow-flowing, lakes) along a continuous ~10 km segment in two catchments in northern Sweden. Hydraulic geometry relationships for width were very weak, indicating that although channel width does increase in the downstream direction, there is very large local variation in width, within and among process domains. Riparian vegetation richness did not increase markedly downstream as expected in a connected stream network, and there are very weak relationships between riparian vegetation composition similarity among reaches and distance between reaches, indicating that hydrochory plays a minor role plays in metacommunity organization. Formerly continentally-glaciated catchments are thus highly fragmented and local factors steer geomorphic form and biotic organization.