Common Even-Aged Systems

1. Common Even-Aged Systems Clearcut Seed Tree Shelterwood

2. Clearcutting • Clearcutting: A method of regenerating an even aged stand in which a new age class develops in a fully exposed microclimate after removal, in a single cutting, of all trees in the previous stand. • Silvicultural clearcuts differ from ‘commercial clearcuts’

4. Clearcutting changes the microenvironment • Full sunlight conditions • Air and soil temperature near the surface increases • Humidity decreases and surface evaporation increases • Soil moisture increases because transpiration decreases • Precipitation interception decreases, more water reaches the surface • Water infiltration and percolation increases; subsurface flow increases • Decomposition increases (warmer and wetter), releasing more nutrients • Nutrients not taken up or bound to soil leach out of system

5. Clearcutting • Edge effect

6. Clearcutting • Alternate clearcutting arrangements • Use of alternative methods:

7. Alternative Clearcutting Approaches Block clearcutting

8. Alternative Clearcutting Approaches Progressive strip clearcut Alternate strip clearcut Strip clearcuts, alternate or otherwise, are best oriented at right angles to prevailing winds. The width of the strips will depend on seedfall distances for the preferred species, wind hazard, and other factors

9. Alternative Clearcutting Approaches Patch clearcutting

10. Other considerations when using even-aged methods • Stream Side Management Zones (SMZ’s) • Legacy trees • Travel corridors for wildlife • Management of viewscapes • Alter shapes, adjacencies • Limit harvest size

11. Clearcutting and Site Preparation • Site preparation considerations for natural regeneration • Some important questions

12. Site preparation and clearcutting: Considerations for natural regeneration • Scarification → mineral seedbed • Control slash residues • Mechanical or chemical vegetation control

13. Advantages of the clearcutting method/system • Commercially attractive • Ease of administration and implementation of regulated forest • Good method for most shade intolerant species • Clean site eases site preparation and pest control • Easy machine access eases harvesting • Total overstory removal reduces some pests (e.g. dwarf mistletoe) • Facilitates regeneration of species with serrotinous cones • Precludes blow down • Increases herbaceous cover (browse and cover for many wildlife species)

14. Shortcomings of clearcutting with natural regeneration • Problems with dependable seed sources and seedling establishment • Issues associated with no high forest cover and high light environment • Reduced chance for genetic improvement

15. Shortcomings of clearcutting with natural regeneration • Impacts on soils and hydrology • Decreased visual aesthetics • Increased fuel loading and fire danger • Decreased wildlife habitat for some species

16. Coppice Silviculture

17. Coppice • The term "coppice" is commonly applied to any regeneration arising from sprouts or suckers—typically hardwoods of young to moderate age • As a method, it is where regeneration is solely from sprouts or root-suckers • Associated with short rotation production of pulpwood or fuelwood • Historically associated with charcoal iron production

19. Coppice • Some coppice principles: • Low stumps produce better quality sprouts • Sprouting vigor tends to decline with age and size of stems • Sprouting is most vigorous from dormant season cutting

20. Coppice • Coppice for energy, bioremediation, environmental cleanup • Repeated crops without replanting • Vegetative propagation maintains genetic integrity of plantation • Increased growth rates allow large volume production on limited land base • Short cycle provides quick return on investment • Second and third rotation often produces greater biomass in shorter time frame due to multiple stems from sprouts

23. Coppice • The cutting cycle is set by when the MAI intersects PAI

25. General shortcomings of coppice systems • Financial success depends on access to markets for small diameter wood • Serve limited set of management goals • Frequent entry requires extra caution to minimize soil disturbance and may increase loss of soil nutrients after repeated harvests • Coppices susceptible to freezing and browse • It takes time to convert from coppice to high forest methods • Coppice stands have limited non-market values • General shortcomings of short-rotation biomass plantations • Require guaranteed markets • Require fertile soils with abundant moisture as well as fertilization to maintain critical nutrients • May require protection from browse • Mechanized systems needed for efficient harvesting require fairly level sites with uniform surfaces and highly trafficable soils.

26. Coppice with standards: scattered, individual stems allowed to grow on through several coppice cycles

27. Seed Tree Method • Definition: even-aged method retaining widely spaced, uniformly distributed seed bearing trees • Reproduction source: from seeds disseminated from trees left after harvest

28. Seed Tree Method • Remaining seed trees may be removed after suitable regeneration is established, but this is not necessary to the method's application • Produces an even-aged stand • Inherently works well for wind dispersed species, but not hard seeded trees such as oaks and hickories • The method removes size constraints on the regeneration area (also shape and orientation issues)

29. Seed Tree Regeneration Method • Regeneration must be established in a short period of years, or else the site will be occupied by other plants • Produces early successional conditions on the site (the same as a clearcut):

30. Key considerations for the seed tree method Number and spacing of seed trees depends on:

31. Considerations for number and spacing: • Distance to which seed from desired species can be dispersed to fully stock an area • Nature of the seedbed • Anticipated competition level • Above all, know the silvics of species to be retained

32. Considerations for number and spacing: • In general: • Light seeded trees can disseminate 2 to 5 times their height • Amount of viable seed is usually limiting factor • Influence of spacing on pollination alter total seed production • Because of year-to-year variation in seed production, it is best to ensure enough reserve trees to restock area in one moderate seed year • Usually, 4 to 20 trees per acre retained.

33. 8 seed trees per acre in a loblolly-shortleaf pine stand. Arkansas.

35. Characteristics of Quality Leave Trees • Windfirmness • Wide, deep crowns, with high live crown ratio • Height • Age

36. Cutting Strategies – Seed Tree System • Prep Cut: Optional initial treatment to increase tree vigor and seed production • Seed Cut: Treatment to establish seedling reproduction within the stand • Removal Cut: Removal of final overwood to release established seedlings • Additional Management options: • Reserve Cutting: retain seed trees to help make an early thinning of the next stand more economically feasible • Not competing removal cut and retaining seed tree through next rotation to meet multiple-use objectives.

37. Key Considerations for the Seed Tree Method Site Conditions: An adequate seedbed and low level of competition are required • Some well-distributed exposed soil is desirable, since seeds are small • Dispersed skidding during logging may be sufficient, particularly if the stand has been burned regularly • Consider a prescribed burn (for pines) if a heavy litter layer exists • Mechanical site preparation

38. Key considerations for the Seed Tree Method • Reduce anticipated competition, if needed • Logging operations can damage competition vegetation present at time of harvest • Use a burning regime prior to harvest • Consider using herbicides or herbicide/burn combination

39. Key considerations for the seed tree method Final removal of seed trees is an economic consideration as they do not modify the microenvironment • You may consider increasing numbers of seed trees in order to make the final harvest merchantable • Conversely, you may retain a few (but high quality) trees in order to make the first thinning more attractive financially

40. Seed Tree Removal Consideration • Do economic gains out-weight positives to retention? • Damage to established reproduction • Is area fully stock with reproduction? • Additional site preparation may be necessary if reproduction does not develop • If removal is chosen and growth of established reproduction is your #1 objective…

41. Advantages to Seed Tree Method: • Allows for the control of species and phenotypic characteristics of seed source • Seed source abundant and uniformly spaced • Provides full sun growth conditions • Disadvantages: • Exposes seed source to increased risk of premature destruction. • Does not provide protection to reproduction on harsh sites • Application of Seed Tree Method:

42. Ponderosa Pine Shortleaf Pine Slash Pine

43. Shelterwood System • Definition: an even-aged silvicultural system where the reproduction method removes mature community in two or more successive cuttings, temporary leaving some old trees to serve as seed source and to protect the regeneration. • Characteristics: • Relatively low density stand left of vigorous seed-bearing trees • Residual overstory provides sufficient canopy to mitigate sensitive environmental conditions. • Residual trees are removed once new reproduction reaches adequate size (i.e. height) and density

44. Uniform Shelterwood Components • Preparatory Cut An optional initial treatment to:

45. Uniform Shelterwood Components (continued) 2. Establishment Cut • Artificially moves stand into understory reinitiation phase of stand development • Promotes seed germination and establishment by creating permanent openings in main canopy • Opens the canopy for sufficient light availability to allow regeneration • Maintains some control (“shelter”) of understory vegetation

46. Uniform Shelterwood Components (continued) 2. Establishment Cut Considerations for success:

47. Uniform Shelterwood Components (continued) 3. Removal Cut • A harvest to take away the overwood, so the new reproduction can develop uninhibited. • Conducted only after satisfactory establishment of reproduction based on density, height, and distribution of seedlings • Will impact (i.e. damage) established reproduction • Remove the overwood before suppression of regeneration becomes serious

48. Shelterwood Method/System • Applicability of the Shelterwood Method • It is the most flexible even-aged method: e.g., you can delay the removal cutting in order to: • A good method for heavy-seeded species • A good method where the seed supply is irregular

49. Uniform Shelterwood Methods • Three-cut Method: Preparatory, Establishment, and removal cut are used • Two-cut Method: Establishment and Removal cut only

50. Shelterwood Method/System • How Much Overwood Do You Leave? • Will crown closure of residuals occur • What effect will the overwood have on the reproduction • Consider the minimum volume to support merchantable overwood removal • Consider the volume that will accumulate on the residual overwood stems • Ease of logging (seed and removal cutting) • Logging damage to reproduction • Could be positive aspect and considered a no-cost thinning operation if density is too high *Applicable to both seed tree and shelterwood methods