1. Concepts of Forest Regeneration

2. Regeneration vs. Reproduction
Regeneration: the act of renewing tree cover by establishing young trees naturally or artificially (verb)
Reproduction: Seedlings or saplings existing in a stand (noun)

3. Artificial vs. natural regeneration
Natural Regeneration - stand establishment is from natural sources: natural seeding, sprouting, suckering, layering
Artificial Regeneration - stand establishment is from human intervention: planting seedlings or cuttings or by direct seeding.

4. Reforestation vs. afforestation
Reforestation: reestablishment of forest cover on areas where it once occurred
Afforestation: introduction of trees to sites that did not support forests or had no forest cover for a long period of time.

5. Concepts of Regeneration
Key goals of a regeneration strategy:
Make the results predictable
Control microenvironment
Ensure prompt replacement of the stand
Affect species composition
Match species to site and to objectives
Arrest succession
Many desirable species are early successional (oak and pine)

6. Concepts of Regeneration
Key goals of a regeneration strategy:
Appropriately stock the site with desirable species
Number and distribution
Set the stage for future management
Minimize poor or excessive stocking
Minimize remedial treatments (problems that require fixing)
Intermediate treatments should, where possible, be constructive
Minimize the chance of failure
Ensure adequate seed supply
Ensure proper seed bed for good germination and establishment
Take prompt remedial action if necessary

7. Concepts of Regeneration
Origin of reproduction
Seed vs. vegetative
New individual vs. clonal

8. Categories of Reproduction
New seedlings: originate following regeneration event
Advance reproduction: in place prior to regeneration event and released by event
Stump sprout: traditionally from stump >2” ground line diameter
Root suckering: sprouts from shallow lateral roots
Typically follows the severing of the parent stem and with direct sunlight to the forest floor
Examples: black locust, sweetgum, aspen

9. Stump Sprouting

10. Stump Sprouting Probability by Age and Species
Sprouting tends to decrease with size and age and varies by species
Stump Sprout
Probability
Tree Age

11. Regeneration Process
New forest communities establish whenever three conditions develop:
Presence of abundant viable seed or vegetative propagules
Soil and seedbed conditions enable germination of seed or help induce shoot development off parent trees
Environmental conditions foster the survival and growth of established trees

12. Regeneration Process Seed Supply Flowering and seed production
Influenced by species, genetics, climate
Can be cyclical and have high year-to-year variation
Example: masting species such as oaks

13. Regeneration Process Seed dispersal
Reproductively mature trees within dissemination range required for regeneration from seed
Vegetative or artificial regeneration required if seed is not available
Factors influencing seed dissemination (i.e., dispersal)
Height of release
Distance from source
Abundance of seed
Weight and aerodynamic structure
Activity of dispersing agent
Wind speed and direction, topography, numbers and movement of animals

14. Seed dispersal distance is species dependent

15. Regeneration Process Seed bank
Viability and germination stimuli various among species

16. Regeneration Process Seed Bed and Germination
Physical characteristics of forest floor affect germination
Litter depth and type
Some species (for example, many pines) require a mineral seedbed
Mineral seed beds can created by natural disturbances (i.e. fire) or site preparation treatments
Position of seed within the seedbed affect predation and germination rates
Light, temperature, and moisture affect seed viability and germination

17. Concepts of Regeneration
Generally,
Light wind-disseminated seeds require mineral seedbed
Large seeded species like oaks are aided by being buried under a litter layer as long is it is not too thick (5 cm)
Litter layer helps protect against predation, desiccation, and extreme temperatures

18. Species of the Central Hardwood Region
Seed Dissemination
Gravity
Animals
Wind
Yellow-poplar X
White oak
Chestnut oak
Black oak
Northern red oak
Scarlet oak
Sugar maple
Red maple
Pignut hickory
American beech

19. Regeneration Process Established Seedlings
Survival and growth of seedlings influenced by mitigating effects of forest canopy on light, temperature, and moisture in the understory
Species physiologic characteristics and shade tolerance affect their response to a given understory environment
Silvical characteristics of desired species must be considered in conjunction with those of competitor species to assess competitive dynamics of newly established seedlings.

20. Regeneration Process Established Seedlings and Shade Tolerance
Shade tolerant: Not only are they able to establish in the understory, but they are able to persist.
This doesn't necessarily mean they are putting on a lot of growth, but they are staying alive
Intermediate tolerance: Able to establish in the understory but they cannot survive for extended periods
Shade intolerant: May establish in the understory, but normally die out in dense shade
When released following extended periods of low light they respond with sluggish growth

21. Overview of Silvicultural Systems
Even-aged vs. Uneven-aged

22. Common characteristics of even-aged stands
Crown canopy is generally limited to a single layer elevated above the ground
Diameters vary widely only if shade-tolerant species are present
Only old stands have sawtimber sized trees
Small trees have short live crown length when compared to total height
Largest trees often have percent live crown, depending on stand density

23. Common characteristics of uneven-aged stands
Crown canopy is generally comprised of multiple layers and commonly extends close to the ground
Diameters range from seedling-sapling to sawtimber sizes, regardless of species present
Trees of all diameters have a large live-crown ratio, often as high as 40 to 60 percent in managed stands
Tree heights vary with tree diameter, with short ones having small diameters and tall trees having larger diameters

24. Even-aged vs. Uneven-aged Diameter Distributions
Bell-shaped (normal distribution)
Reverse J-shaped

25. Reverse J-shaped does not always indicate a true uneven-aged stand (3+ age classes)
Example from the Central Hardwood Region: Two-storied stand with oak-dominated overstory and midstory/understory canopy dominated by shade tolerants like beech and maple.

26. Silvicultural Systems
Even-aged and Uneven-aged systems
One age class vs. at least three age classes in a stand (an age class is defined at 20% of the rotation length)
Mature trees are removed:
Short window of time in even-aged
Periodically in uneven-aged
Maintains continuous canopy cover

27. Timeline of practices in an even-aged silvicultural system
During the rotation age r, treatments are applied across the entire stand to meet silvicultural objectives that are related to tree age

28. Concurrent application of individual practices of an uneven-aged silvicultural system during a cutting cycle harvest in a balanced uneven-aged stand
Treatments are applied to subunits of the stand depending on conditions within each subunit
Each cutting cycle harvest will support similar treatments

29. Silvicultural Systems
Two-aged systems
Hybrid of even- and uneven-aged
Uses even-aged methodology while maintaining some continual canopy cover
Regeneration is accomplished two times over a standard rotation
Referred to as: irregular shelterwoods, reserve shelterwoods, two-aged, or leave tree systems

30. Regeneration Methods Regeneration methods are classified as follows:
Even-aged
Clearcut
Seed-tree
Shelterwood
Uneven-aged
Selection
Two-aged (Hybrid)