Eric Merten Jacques Finlay* Heinz Stefan* Lucinda Johnson Raymond Newman Bruce Vondracek

1. Instream wood transport, and effects of forest harvest on geomorphology and fish, in northern Minnesota streams Eric Merten Jacques Finlay* Heinz Stefan* Lucinda Johnson Raymond Newman Bruce Vondracek This work was funded by the Minnesota Department of Natural Resources Section of Fisheries, the Minnesota Forest Resources Council, the National Council for Air and Stream Improvement, the U.S. Forest Service, Minnesota Sea Grant, Minnesota Trout Unlimited, and the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative Citizen Commission on Minnesota Resources.

2. Forest harvest effects on the Pokegama Creek system: 1997 to 2007 http://www.youtube.com/watch?v=up7-xHm6jlA Ecohydraulics of wood transport in north shore streams

3. Pokegama sampling help Andy Arola Daryl Arola Brenda Asmus Jason Bronk Ryan Carlson Jacquelyn Conner Bill Coates Carrie Dorrance Sue Eggert Art Elling MaryKay Fox Jo Fritz Sarah Harndin

4. Pokegama sampling help Nat Hemstad Becca Hunt Deacon Kyllander Marty Melchior Steffen Merten Mateya Miltich Brittany Mitchell Erik Mundahl Elliot Nitzkowski Ian Phelps Lisa Pugh Jeff Rice Jeremy Steil Sandy Verry Dustin Wilman Jason Zwonitzer

5. April Bebault Ryan Carlson Tracy Close Levi Drevlow Jo Fritz Ryan Johnsen Nicole Rath Marty Rye Nathan Schroeder Rachael Stanze Dustin Wilman Wood sampling help >6km surveyed every 10m Rachael ongoing discharge data, Tracy Close sharing data

6. The Many Roles of Trees

7. Purpose: To evaluate Minnesota’s voluntary Best Management Practices (BMPs) for timber harvest (1996)

8. Local Research: • Merten (1999) found significant fine • sediment increase after harvest • Hemstad, Merten, and Newman (2008) found fine sediment levels persisted for several years • Hemstad and Newman (2006) found more eroding banks and fine sediment 0-2 years after harvest in the catchment

9. Experimental design • Pre-harvest sampling in summer 1997 • Forest harvest in winter 1997-1998 • Post-harvest sampling summer 1998 • through summer 2000 • Natural recovery of sites • Post-harvest sampling in summer 2006 • through summer 2007

11. Analysis • Repeated measures ANOVA using all • data from all sites • Tests for overall differences between • years, throughout the study area • Can not determine the causes of the • differences

12. FOREST HARVEST

14. C FOREST HARVEST

15. D FOREST HARVEST

20. , p= 0.05 , p= 0.05 , p= 0.00 , p= 0.03

21. Pokegama Summary • Canopy cover and eroding banks recovered nine years after harvest • Sediment inputs still present nine years after harvest, flushed in fall of 10th year • Years with warmer air temperatures may exacerbate effects of open canopy and fine sediment

22. Ecohydraulics of wood transport in streams: empirical models from the north shore of Lake Superior in Minnesota

23. Why study wood transport? If a wood piece is exported from a stream reach, it no longer provides geomorphic or ecological functions there

24. Plunge pools Lateral migration Habitat complexity Invertebrate substrate Leaf litter retention Transient storage Hyporheic exchange

25. Needs for wood transport studies Research questions for this project Data collection Data analysis Results and discussion

26. Needs for wood transport studies Location: managed forests in the interior U.S.

27. Needs for wood transport studies Location: managed forests in the interior U.S. Design: high resolution but still a field study

28. Needs for wood transport studies Location: managed forests in the interior U.S. Design: high resolution but still a field study Predictors: examine relative importance of all known mechanisms

29. Needs for wood transport studies Research questions for this project Data collection Data analysis Results and discussion

30. Mobilization Entrapment

31. Needs for wood transport studies Research questions for this project Data collection Data analysis Results and discussion

32. ~2000 hours sampling on nine streams

33. Nine streams between Duluth and Silver Bay

34. Bankfull widths ranged from 3.3 to 25.1 m

35. 963 pieces measured and tagged, many variables measured 4,190 m of stream surveyed every 10 m

36. Braced against a live tree Saldi-Caromile et al. 2004

39. Needs for wood transport studies Research questions for this project Data collection Data analysis Results and discussion

40. HEC-RAS model

41. HEC-RAS model

44. Drag force ≈ (U 2/2) ρw Cd AN + (U 2/2) ρw Cf ASAcos3 θ Lift force ≈ U 2/2 Clp ANcos θ + U 2/2 Clg ANsin θ Braudrick and Grant 2000

45. “What factors determine whether or not a piece is mobilized/entrapped?” Multiple logistic regression with mobilization as the response variable -shows which variables are important for mobilization Multiple logistic regression with entrapment as the response variable -shows which variables are important for entrapment

46. Needs for wood transport studies Research questions for this project Data collection Data analysis Results and discussion

47. Needs for wood transport studies Location: managed forests in the interior U.S. Design: high resolution but still a field study This study examined individual pieces in the field at a fine spatial scale and at a < 1-year temporal scale Predictors: examine relative importance of all mechanisms This study examined more and better predictors than any previous study

48. Variables retained in the final model for mobilization; n = 865 pieces of wood. Overall model p < 0.001 and Nagelkerke’s r2 = 0.39

50. Variables retained in the final model for mobilization; n = 865 pieces of wood. Overall model p < 0.001 and Nagelkerke’s r2 = 0.39