Wayne K. Clatterbuck Silviculture & Forest Management Forestry, Wildlife & Fisheries

1. Single-cohort Mixed Species Deciduous Stands Exhibiting Multi-cohort Attributes in the Southeastern United States Wayne K. Clatterbuck Silviculture & Forest Management Forestry, Wildlife & Fisheries University of Tennessee, Knoxville wclatterbuck@utk.edu

2. Overview 1. Examine stand structure in four stands within east TN with seemingly multi-cohort attributes 2. Hypothesize why stands are actually single-cohort 3. Are multi-cohort stands feasible in these forests?

3. Study Area Selection • Second Growth Stands from a Stand Initiation Disturbance • Age > 100 years, no major disturbances during period • Multiple Canopy Layers • At least 20 ha in size • Government-owned – state or federal

4. Four Study Areas • Cumberland Mountains (East Tennessee) • Cumberland Plateau (East Tennessee) • Smoky Mts National Park (East TN) • Pisgah National Forest (Western North Carolina)

5. Site Characteristics • Productive Cove Hardwood Forest Types, SI = 28 m at 50 years, mesic sites • 65 inches or 160 cm annually • Composed of more than 25 species • Located in concave areas that escaped weather events that are frequent

6. Species • Shade Intolerants --- Yellow-poplar, black cherry, black walnut, sweetgum, sycamore, cottonwood • Intermediates --- white oaks, red oaks, hickories, ash • Shade Tolerants --- red maple, hornbeam, sourwood, dogwood, buckeye, elm

7. Species • Though sugar maple and American beech are present, they are on outskirts of range and are not prominent • Assumption: too warm and humid for these species • No commercially available shade-tolerant specie present, making multi-cohort management problematic

8. Diameter Distribution 1 hectare = 2.4 acres 1 inch = 2.5 centimeters

9. Diameter Distribution All 4 Study Areas had similar diameter distributions 1 hectare = 2.4 acres 1 inch = 2.5 centimeters

10. Structure • Negative exponitial (reverse J-shaped) diameter curves • Multi-species with different shade tolerances • All within the same age range (+ or - 10 years), EVEN-Aged or single-cohort

12. Diameter Distribution Composed of shade-tolerant, non-commercial species --- (Cornus, Oxydendron, Nyssa, Acer rubrum, Sassafras, Ulmus) 1 hectare = 2.4 acres 1 inch = 2.5 centimeters

13. Why Single-Cohort and Differing Diameters? • Mixed Species • Stand-Initiating Disturbances

14. Mixed Species • Different species grow at different rates (tolerances) • Different regeneration mechanisms • Different rates to maturity by species • Different responses to disturbance Different ???

15. Disturbance • Disturbance is rampant on the landscape • Varies by frequency and intensity • Natural and anthropogenic

16. Difficulties with Multi-Cohorts • Frequent stand initiating disturbance • Windstorms ---- tornados, hurricanes, storms • Fire --- formerly more prevalent • Insects/Disease outbreaks

17. Source: Kim Coder, University of Georgia Average Number of days with thunderstorm events each year

18. Source: National Geographic

19. Source: National Weather Service

20. Insects & Disease Invasives • Emerald Ash Borer • Thousand Cankers Disease of Walnut • Hemlock Woolly Adelgid • Gypsy Moth • Southern Pine Beetle • Oak Decline

21. Difficulties with Multi-Cohorts 2. Ecology of the various species present • No commercially available shade-tolerant species • Aggressive Liriodendron (yellow-poplar) --- a pioneer and late successional species • Do not know species composing late-successional complex because of frequent disturbance • Thus, must pay attention to regeneration to be sustainable

25. Difficulties with Multi-Cohorts 3. Short ownership intervals • 85% of forest land (4.6 million ha) in Tennessee are in private woodland ownership • According to last Woodland Owners Survey, average forest tenure is 12 to 15 years Difficult to maintain multi-cohort stands with constant turnover

26. Difficulties with Multi-Cohorts 4. Surrogate of using diameter rather than age in representing multi-cohort stands • Large diameter trees are not necessarily old • Small diameter trees are not necessarily young • Wide variation in development of multi- species stands

27. Bottomline Question: Do we desire multi-cohort stands in mixed mesophytic forests? We already have the structure w/o much effort, although single-cohort

28. Bottomline Stands are: • Complex / Variable / Heterogenous • Functionally Resilient • Flexible/Adaptable • Challenging because of frequency of change

29. Bottomline The challenge for multi-cohort stands is: • Regenerating acceptable species (primarily intolerants and intermediates) in the shade of the overstory when desirable shade tolerants are not part of the system

30. Bottomline • Even with the rapidity of major disturbances, we can create even more variability, if desired, through incomplete disturbances, more than likely on an area basis (groups and small patches) • Challenge is still regeneration of favored species

31. Bottomline • Sustainability in these frequently disturbed systems is an open question because of the difficulties in regeneration • But still many opportunities !!!

32. Next • Creating and maintaining stable, mixed hardwood-pine stands (oak-pine) when each component is favored at different successional stages and with varying longevities • Stay Tuned

35. Questions?