Restoration of an invaded riparian zone influences stream macroinvertebrate biomass

In the Midwest USA many riparian plant communities are heavily invaded by Amur honeysuckle (Lonicera maackii: hereafter honeysuckle), creating a dense canopy over headwater streams. Management practices aim to remove riparian honeysuckle; however, it is not well understood how these practices influence stream ecosystems. In this experiment, honeysuckle was removed from a headwater stream reach with a dense honeysuckle riparian forest. We investigated how this “restoration” activity influenced in-stream macroinvertebrate biomass dynamics compared to a “control” reach where the honeysuckle invasion remained intact. We predicted removal of honeysuckle would (H1) increase overall macroinvertebrate biomass, (H2) increase in detritivore functional feeding group (FFG) biomass. In August-September 2010, honeysuckle was removed along Black Oak Park stream in Centerville-Washington Park District, OH, creating a 150-meter honeysuckle removal reach and an upstream honeysuckle (control) reach. Aquatic macroinvertebrates were collected with a Surber sampler monthly from August 2010 to December 2014 within both reaches (n = 5/reach) and identified to genus when possible. Macroinvertebrate body metrics were measured with a micrometer using Image J software. Macroinvertebrate biomass (i.e. standing stock biomass) was estimated for each taxon and FFG using length-mass allometric equations. Preliminary analyses indicated honeysuckle removal did not significantly influence macroinvertebrate biomass; although, there was a clear pattern of increased biomass in the removal reach. Collector-filterer and the collector-gatherer FFG comprised the greatest overall biomass in both reaches. These preliminary results suggest removal of Amur honeysuckle impacts the overall aquatic macroinvertebrate biomass, potentially influencing the flow of energy within the stream food web