Baltimore Ecosystem Study: Invertebrate and Restoration Habitat Data

An often-cited benefit of river restoration is an increase in
biodiversity or shift in composition to more desirable taxa. Yet, hard
manipulations of habitat structure often fail to elicit a significant
response in terms of biodiversity patterns. In contrast to
conventional wisdom, the dispersal of organisms may have as large an
influence on biodiversity patterns as environmental conditions. This
influence of dispersal may be particularly influential in river
networks which are linear branching, or dendritic, and thus constrain
most dispersal to the river corridor. As such, some locations in river
networks, such as isolated headwaters, are expected to respond less to
environmental factors and less by dispersal than more well-connected
downstream reaches. We applied this metacommunity framework to study
how restoration drives biodiversity patterns in river networks. By
comparing assemblage structure in headwater versus more well-connected
mainstem sites, we learned that headwater restoration efforts
supported higher biodiversity, exhibited more stable ecological
communities compared with adjacent, un-restored reaches. Such
differences were not evident in mainstem reaches. Consistent with
theory and mounting empirical evidence, we attribute this finding to a
relatively higher influence of dispersal-driven factors on assemblage
structure in more well-connected, higher order reaches. An implication
of this work is that, if biodiversity is to be a goal of restoration
activity, such local manipulations of habitat should elicit a more
profound response in small, isolated streams than in larger downstream
reaches. These results offer another significant finding supporting
the notion that restoration activity cannot proceed in isolation of
larger scale, catchment level degradation. This dataset represents the
microhabitat sampling.