Matthew Landis Dept. Biology, Middlebury College rlandis@middlebury

1. Climate change effects on New England montane forests: evidence from the past, implications for the future Matthew Landis Dept. Biology, Middlebury College rlandis@middlebury.edu

2. New England forests – 2100? Iverson and Prasad, 1998 http://www.fs.fed.us/ne/delaware/atlas

3. The deciduous – coniferous ecotone

4. Cogbill and White, 1991

5. Past and future changes • Has the location of the DCE changed in the past? • witness tree surveys – comparison with present-day • What sets the DCE? How will it respond to future climate change? • a demographic approach – which life stages are most affected? • What is the role of sapling competition vs. direct climate factors?

6. Changes in New England climate since 1895 Keim and Rock, 2001

7. Elevation shift in the ecotone – an upper limit • 1.1° C change in annual temperature since 1895 (Keim and Rock, 2001) • Lapse rate: • 0.61° C / 100 m (Siccama 1974) • 0.57° C / 100 m (Richardson et al. 2004) • ~ 150 – 200 m shift in the deciduous/coniferous ecotone • e.g. 800 m -> 600-650 m in 1780’s

8. Witness tree survey records • Surveyor’s records from original lotting surveys (1780’s – 1790’s) • Vermont is unique – surveyors covered even the high elevations • Maps obtained from C. Cogbill, Vermont State Archives, Town Offices • 10 towns digitized

9. Sampled towns

10. 950 trees from 88 m to 1119 m (most between 200 and 700 m) Elevation error estimated at 15 m (based on 75 m buffer) beech, birch, maple, spruce comprised 88% of all trees Witness tree locations

11. Forest composition– 1780’s • Ecotone (?) • Upper limit of • beech: 875-900 m • maple: 820-860 m

12. 9 transects across the DCE Point-centered quarter every 25 m elevation (625 m – 975 m) Up to 15 points per transect Present day sampling locations

13. Forest composition– 2006 • Ecotone 800-850 m • Upper limit of • beech: 850 m • maple: 825 m

14. 1780’s 2006

15. Summary • Ecotone much less pronounced in 1780’s than now • Much greater abundance of red spruce in 1780’s • Upper limit of beech and maples has not increased over the past 200 years

16. Sapling competition across the DCE

17. Cogbill and White, 1991

18. Performance Colder Warmer Temperature Loehle 2000

19. Mt. Abraham, VT (1221 m)

20. Methods • Locate gaps across DCE (680, 740, 770, 800, 830, 890) • Measure extension growth (internode length) of dominant saplings • Multiple regression to control ‘nuisance’ variables (height and light) • Measured size distribution along gradient

25. growth = height + canopy openness + elevation

26. 0.15 0.05 NS 0.04 0.16 0.15

27. Sapling growth partially consistent with adult abundance

28. n = 5 plots at each elevation

29. Conclusions • No support for parabolic model of sapling growth • Suggestion of trade-off model – competition between species likely to delay invasion of northern hardwoods • Weak trends in growth along gradient suggest other performance parameters and life-history stages likely to play a strong role

30. Acknowledgements • Charlie Cogbill • Undergraduate research assistants: Alyse Forrest, Sarah Fortin, Kerry Cebul, and Jill Morrison • Bill Hegman, Middlebury College • Vermont EPSCoR • Middlebury College • U.S. Forest Service • Vermont Dept. Forests, Parks, and Recreation

31. Browsing varies by species and elevation

35. www.esd.ornl.gov

36. ABBA