Breeding Bird Community Continues to Colonize Riparian Buffers Ten Years after Harvest

PLoS One. 2015 Dec 4;10(12):e0143241. doi: 10.1371/journal.pone.0143241. eCollection 2015.

Abstract

Riparian ecosystems integrate aquatic and terrestrial communities and often contain unique assemblages of flora and fauna. Retention of forested buffers along riparian habitats is a commonly employed practice to reduce potential negative effects of land use on aquatic systems. However, very few studies have examined long-term population and community responses to buffers, leading to considerable uncertainty about effectiveness of this practice for achieving conservation and management outcomes. We examined short- (1-2 years) and long-term (~10 years) avian community responses (occupancy and abundance) to riparian buffer prescriptions to clearcut logging silvicultural practices in the Pacific Northwest USA. We used a Before-After-Control-Impact experimental approach and temporally replicated point counts analyzed within a Bayesian framework. Our experimental design consisted of forested control sites with no harvest, sites with relatively narrow (~13 m) forested buffers on each side of the stream, and sites with wider (~30 m) and more variable width unharvested buffer. Buffer treatments exhibited a 31-44% increase in mean species richness in the post-harvest years, a pattern most evident 10 years post-harvest. Post-harvest, species turnover was much higher on both treatments (63-74%) relative to the controls (29%). We did not find evidence of local extinction for any species but found strong evidence (no overlap in 95% credible intervals) for an increase in site occupancy on both Narrow (short-term: 7%; long-term 29%) and Wide buffers (short-term: 21%; long-term 93%) relative to controls after harvest. We did not find a treatment effect on total avian abundance. When assessing relationships between buffer width and site level abundance of four riparian specialists, we did not find strong evidence of reduced abundance in Narrow or Wide buffers. Silviculture regulations in this region dictate average buffer widths on small and large permanent streams that range from ~22-25 m. Guidelines for this region are within the range of buffers included in our study, in which we observed no evidence for avian species loss or for a decline in species abundance (including riparian associated species).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bayes Theorem
  • Birds / physiology*
  • Breeding*
  • Conservation of Natural Resources / methods*
  • Ecosystem
  • Northwestern United States
  • Rivers
  • Trees

Grants and funding

All funding sources: The Cooperative Monitoring, Evaluation, and Research (CMER) Committee under Washington Department of Natural Resources provided the 10 year resample data to the authors and provided funding to Washington Department of Fish and Wildlife to pay for Scott Pearson’s salary associated with data analysis, writing and report preparation (Interagency Agreement 12–118). Other funding sources included Washington Department of Fish and Wildlife funding of Scott Pearson’s salary associated with manuscript preparation and Weyerhaeuser who funded Jack Giovanini, Jay E. Jones, and Andrew J. Kroll’s salaries while they analyzed data and co-authored the manuscript. Revised funders website: http://www.dnr.wa.gov/.