A Synthesis of the Impacts of Contemporary Forest Practices on Aquatic Ecosystems at a Watershed Scale: A Case Study from Hinkle Creek A Skaugset, M Adams, D Bateman, K Cromack, L Ganio, B Gerth, B Gresswell, J Li, S Meininger, A Simmons, C Surfleet, and N Zegre
Researchers • Graduate Students • Aaron Berger • Becca Miller • Fey Egan • Hazel Owens • Kelly Kibler • Lance George • Mark Novick • Matt Meadows • Niels Leuthhold • Nick Som • Nicolas Zegre • Scott Meininger • Tim Otis • P.I.s • Arne Skaugset • Bob Gresswell • Judy Li • Kermit Cromack • Lisa Ganio • Mike Adams • Faculty Research Assistants • Alex Irving • Amy Simmons • Bill Gerth • Chris Surfleet • Dave Leer • Doug Bateman • Emily Sinkhorn • JanelSobota • Nicolas Zegre • Rich Van Driesche • Steve Clark • Tim Royer And our many field crews, lab technicians, and associates. Thank you!
Physical Setting • Foothills of the southern Oregon Cascades • Igneous geology (basalt and rhyolite flows) • Deep, well-drained gravelly to clay loam soils • Mean annual precipitation (MAP) ~ 1,480 mm (58 in) • 60-year old, harvest regenerated, Douglas-fir forest • Owned and managed by Roseburg Forest Products.
Hinkle Creek Paired Watershed Study • Nested, paired watershed study • Total watershed area; 1,941 ha (4,794 acres) • Control watershed NFH; 857 ha (2,117 acres) • Treatment watershed SFH; 1,084 ha (2,677 acres) • Nested control watersheds; Meyers & DeMerrsmann • Nested treatment watersheds; Fenton, Clay, Russell, & BB
Hinkle Creek Paired Watershed Study • 2001 • 3 harvest units in place • 2005 – 2006 • Adjacent to non-fish-bearing streams • 152 ha (380 acres) of clearcuts in 5 units • 12.2 mmbf and 3,281 loads of logs • 2008 - 2009 treatments: • Adjacent to fish-bearing tributaries and main stem • 131 ha (324 acres) in 4 clearcuts • 7.6 mmbf and 2,059 loads of logs
HARVESTING EFFECTS LOCAL MONTHLY STREAM FLOW
HARVESTING EFFECTS LOCAL PEAK FLOW
HARVESTING EFFECTS DOWNSTREAM PEAK FLOW QUICK FLOW MONTHLY STREAMFLOW
August Low Flow SFH Source: Surfleet & Skaugset. (In press). WJAF
Sediment Yield Increases • Sediment yield results are not consistent with the seminal results in the literature. • Increases in sediment yield are consistent with and are correlated with increases in water yield. • This requires further work to separate increases in sediment yield due to increases in stream power from increases due to an increase in the erosion rate of the watershed.
The net impact of the timber harvest on the non-fish-bearing streams was a 0.5°C decrease in average daily temperature.
Fertilization • Fertilizer was applied to both watersheds in the fall of 2004 • Existing clearcuts and imminent clearcuts did not receive fertilizer • The North Fork received 25% more fertilizer per hectare • Fish-bearing streams: 60 foot buffer strips • Non-fish-bearing streams: no protection • Fenton received no fertilizer
Nitrate response • Strong seasonal fluctuation during the calibration period • Muted seasonal response during the first post-treatment period • More pronounced seasonal response during the second post-treatment period
DataCollection • Sampled only before and after the first entry. • Sampled 100 sites/yr. • Average of 39 were unoccupied.
Invertebrate Response in Headwaters: Percent Chironomids, Increased, Taxa Richness Decreased 2004 2006 - 2009
Tributaries with Fish:No downstream effects on invertebratesafter harvest in headwaters Benthic densities (in this graph), percent chironomids and taxa richness did not differ significantly from controls
Invertebrate Mainstem Responses: Percent ChironomidsIncreased, Taxa Richness Decreased
Mainstem Responses: Lack of invertebrate density response possibly related to fish biomass response
Basin-level Analysis Significant Preliminary Results: Same relationships for Age-1+ CT with 1-yr lag in bothwatersheds Dissimilar relationships for Age-0 CT (no lag) between watersheds Coming soon: Stream-level analysis Owens, H.L. 2013
At this point in time, what do we think we have learned at Hinkle Creek? • For almost every discipline, contemporary forest practices resulted in detectable changes in a parameter of interest. • These changes were often difficult to detect, not acute, often subtle, and the magnitude of the changes existed well within the spatial variability exhibited within the watershed.
Douglas County Thank You!
Invertebrate Response in Headwaters: Densities Increased 2004 2006 - 2009
Annual stream export • Probably a 16-fold increase in annual stream export • A portion of this increase is due to fertilizer • Average input of nitrate from precipitation is approximately 0.7 kg/ha/yr • Input was roughly equal to output
Significant differences were related to increases in production (growth and mass).
Fisheries Summary • Overall, very few detectable changes in habitat or biologic parameters were observed with either treatment. • At Hinkle Creek, Oregon Forest Practices Rules provided adequate short-term protection from acute negative effects to the resident fish community.