Rivers without headwaters are like trees without branches: Integrating network-level ecological connectivity to enhance conservation

Great progress is being made in scaling from stream patches to river networks. This involves 1) comparing patterns and processes from small-to-large scales, 2) using network-level modeling to expand estimates of processes to landscapes, and 3) quantifying connectivity of linked systems - and their spatial heterogeneity - throughout river networks. Ecological connectivity is threatened by global change (land use, climate), while policies that protect such connectivity are being weakened. Headwaters are critical components of river networks that drive important downstream functions and ecosystem services through connectivity. Quantification of spatial connectivity is needed to inform management and conservation of rivers.