Braided rivers in New Zealand are hotspots of biodiversity. A shifting mosaic of habitat patches and landscape elements at different successional stages are the natural state in these river channels and floodplains, and this habitat complexity promotes greater taxonomic diversity and biotic stability. These hydrologically-dynamic floodplain river systems are the nexus of aquatic and terrestrial ecosystems, facilitating the flow of resources and organisms through the landscape and the occurrence of specialist taxa. Despite their unique ecological values, these landscapes are threatened by anthropogenic stressors including flow modification, plant invasion, and land-use encroachment. Such pressures commonly result in structurally simplified habitats. Here, we quantified the long-term stability of community dynamics in 32 New Zealand rivers along a gradient of habitat complexity using a 30-year time-series dataset of annual benthic macroinvertebrates. We modelled temporal changes in community richness and abundance against drivers including channel pattern (channel count and sinuosity), long-term flow regime, and catchment characteristics (vegetation, land-use, geology and climate). Early results indicate that sites with greater habitat complexity, including wandering and braided rivers, show higher biomass stability through time. Yet, within-site community composition in more complex rivers displayed higher variability between consecutive years, likely an indication of portfolio effects underpinning the community dynamics. The demonstrated importance of spatial habitat complexity to community stability, and thus ecosystem resilience, supports the need for freshwater conservation and restoration to act at the landscape scale.