Abstract
We evaluated the ecological effectiveness of an in-stream restoration project involving coarse woody debris (CWD) additions to streams along an upland soil and vegetation disturbance gradient at the Fort Benning Military Installation near Columbus, GA. We examined short-term (immediate effectiveness) and longer-term (sustainability) responses to CWD additions by measuring ecosystem metabolism rates in 8 streams quarterly over a 6-year period, including 3 years before (2001–2003) and 3 years after (2004–2006) CWD additions that were made to half of the streams. Ecosystem respiration (ER) rates in most CWD addition streams increased relative to control streams from spring 2004 through autumn 2005, suggesting heterotrophic bacteria were the initial responders to CWD additions. Gross primary production (GPP) rates remained low (typically < 0.3 g O2 m−2 d−1) but increased in some CWD addition streams relative to control streams in spring 2004 and 2005. The magnitude of ER increases in CWD addition streams during the first two years post-addition increased with catchment disturbance intensity, indicating that more heavily disturbed streams responded most strongly to restorations—an important consideration when targeting future restoration locations. Because restorations did not address actual upland disturbance, continued high erosion rates resulted in 32–77% of the added CWD being buried by year two and a corresponding return of GPP and ER rates to pre-CWD addition levels by year three. If restoration projects do not adequately address the source of catchment disturbances, CWD additions will provide only short-term increases in streambed structure and stability, hydrodynamic complexity, and nutrient and organic matter processing and retention.
| Original language | English |
|---|---|
| Pages (from-to) | 828-842 |
| Number of pages | 15 |
| Journal | Ecosystems |
| Volume | 25 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jun 2022 |
Funding
We thank the personnel at the Fort Benning Military Installation for permitting regular visits to the installation, particularly Hugh Westbury for arranging access to our field sites on the reservation. Pete Swiderek and Gary Hollon provided scientific and logistical advice. Jack Feminella, Kelly Maloney, Richard Mitchell, and Stephanie Miller helped install the CWD dams. We also thank Richard Mitchell for providing data on CWD % areal coverage. Comments of Yetta Jager, KathiJo Jankowski, Emily Stanley, and two anonymous referees greatly improved an earlier version of this manuscript. This project was supported by grants from the US Department of Defense’s Strategic Environmental Research and Development Program (SERDP) to Oak Ridge National Laboratory (ORNL). Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the US Department of Energy under contract DE-AC05-00OR22725. This manuscript has been co-authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
Keywords
- Catchment disturbance
- Course woody debris
- Ecosystem respiration
- Hydrodynamics
- Interannual variability
- Nutrient uptake
- Organic matter
- Primary production
- Seasonal patterns
- Stream restoration