FOR 350 Silviculture

1. FOR 350 Silviculture

2. What is silviculture? The art and science of controlling the establishment, composition, structure, and growth of a forest stand to meet the landowners’ objectives on a sustainable basis.

3. What is silviculture? The art and science of controlling the establishment, composition, structure, and growth of a forest stand to meet the landowners’ objectives on a sustainable basis. • Three parts to the definition • Manipulative, objective driven, sustainable • Silviculture builds on many other disciplines • Ecology, physiology, soils, silvics, economics, mensuration

4. Silviculturists (not silviculturalists) operate in the realm of the biologically possible • Also operate under social and economic constraints • Only solutions that are simultaneously biologically possible, economically feasible, and socially acceptable, will be considered appropriate (and sustainable)

5. To know what is biological possible • One must understand how the forest environment influences individual tree and community establishment and development.

6. To know what is biological possible • One must understand how the forest environment influences individual tree and community establishment and development. • Understanding silvics of the region is critical Silvics is the study of the biological characteristics of tree species and communities of trees including how: 1) trees establish, grow, and reproduce 2) the physical environment influences their physiology and character 3) communities of trees influence their physical environment and the interaction between vegetation and physical environment as forests change through time.

7. Silviculture Is Objective Driven • Silviculturists affect the direction of stand development, but there is often the reality of ‘you can’t get there from here’

8. Silviculture Is Objective Driven • Silviculturists affect the direction of stand development, but there is often the reality of ‘you can’t get there from here’ • Even if you can get there from here (i.e. biological feasible), you need a roadmap, a start and end point

9. Silviculture Is Objective Driven • Silviculturists affect the direction of stand development, but there is often the reality of ‘you can’t get there from here’ • Even if you can get there from here (i.e. biological feasible), you need a roadmap, a start and end point • Objectives and forest inventory data form basis for road map

10. Silviculture Is Objective Driven • Silviculturists affect the direction of stand development, but there is often the reality of ‘you can’t get there from here’ • Even if you can get there from here (i.e. biological feasible), you need a roadmap, a start and end point • Objectives and forest inventory data form basis for road map • Inventory data gives you the starting point

11. Silviculture Is Objective Driven • Silviculturists affect the direction of stand development, but there is often the reality of ‘you can’t get there from here’ • Even if you can get there from here (i.e. biological feasible), you need a roadmap, a start and end point • Objectives and forest inventory data form basis for road map • Inventory data gives you the starting point • Objectives define where you are going

12. The Stand • A stand is a contiguous group of trees sufficiently uniform in age or size class distribution, composition, structure, site quality and/or location to be a distinguishable unit. • Silviculture is practiced at the stand level • Forest management is primarily concerned with the forest (or tract), a collection of stands administered as an integrated unit

13. The Silvicultural System • To meet landowner objectives, silviculturists alter the forest environment by manipulating stand structure • Required environment is influenced by: • Species composition • Silvics of desired species and competitors • Stand structure • Age structure • Health and vigor • Potential damaging agents

14. The Silvicultural System • A silvicultural system encompasses everything that is done throughout a rotation • In theory, it is unique for each stand • The systems are named for their respective regeneration methods (e.g., shelterwood system, single-tree selection system) • Naming convention identifies the structural character of a stand

15. The Silvicultural System • Each silvicultural system should: • Sustain ecosystem health and productivity • Improve tree growth and quality • “Optimize” market and non-market benefits • Shorten investment period and contain costs

16. Categories of Silvicultural Systems • Even-aged System A planned sequence of treatments designed to maintain and regenerate a stand with one age class.  The range of tree ages is usually less than 20 percent of the rotation.  • Uneven-aged System A planned sequence of treatments designed to maintain and regenerate a stand with three or more age classes. • Two-aged (Hybrid) System A planned sequence of treatments designed to maintain and regenerate a stand with two age classes.

17. Silvicultural Systems and Methods • A silvicultural system is named based upon the regeneration method used • Regeneration methods are classified as follows: • Even-aged • Clearcutting, seed-tree, shelterwood • Uneven-aged • Single-tree selection, group selection • Two-aged (hybrid) • Reserve shelterwood, reserve seed-tree, clearcutting with reserves

18. An Example: Phases of an Even-Aged System Establishment

19. Phases of an Even-Aged System Intermediate Treatments • Benefits • Reduce density • Improve growth and quality • Favor desired species • Shorten rotation

20. Phases of an Even-Aged System Site Preparation • Benefits • Improve germination, survival, and growth of desired seedlings • Removal of unwanted vegetation and slash

21. Phases of an Even-Aged System Regeneration Methods • Benefits • Create conditions require to establish new stand of desired species

22. The Silvicultural System • The choice of a method depends on: • Landowners objective • Existing plant community and silvics • Stand conditions • Range of treatments available for use

23. The Silvicultural System • Modifications of a silvicultural method • Type: apply different kinds of treatments • e.g., burn vs. herbicide • Intensity: change the intensity of application • e.g., light vs. heavy thinning • Timing: alter timing of application • e.g., winter vs. summer burn • Sequence: change the sequence of treatments over time • e.g. control vines before or following harvest

24. The Silvicultural System • Modifications often implemented for non-timber considerations: • Size and distribution of regeneration area • Rotation length • Kind, size and condition of residual trees • Species left on site • Amount, kind, and frequency of seed production • Amount of light to forest floor • Coarse woody debris left on site (amount, size, and distribution) • Implementation of Best Management Practices (BMPs)

25. Biologic and economic factors affecting silviculture • Site quality • Stand character and condition • Nature and requirements of an ownership • Accessibility and terrain • Forest products markets

26. Stand Development

27. Four Phases of Stand Development • Stand initiation (reorganization phase) • Stem exclusion (aggradation phase) • Understory reinitiation (transition phase) • Old growth (complex phase, steady-state) • Each phase of stand development is accompanied by changes in stand structure and species composition.

28. Stand initiation: Rapid increase in the number of stems and biomass (establishment) • Structure • Begin vertical stratification of tree crowns • “brushy” stage with herbaceous, shrub, small trees • Invasion continues until all growing space is occupied • Follows major disturbances (wind, fire, clearcuts) • Regeneration of open space from seed, sprouts, or advance reproduction • One age class • Stage ends when canopy becomes continuous and trees begin to compete with each other for light and canopy space

29. Stem Exclusion: Begins at about crown closure, characterized by density dependent mortality and an accumulation of biomass. Phase ends when biomass peaks. • Canopy continues to have one cohort and canopy too density to allow new trees to grow into canopy • Density-dependant “self-thinning” occurs • Crown differentiation occurs: the biggest trees tend to get bigger, the smaller ones tend to die. • Crowns are small enough so that when a tree dies, others fill the vacant growing space by expanding their crowns • Mortality rates are high, especially in intermediate and suppressed crown classes (i.e., the least competitive individuals die).

30. Crown Classification • Dominant: Crown is larger than average and typically above the general upper level of the canopy; receives full top light, considerable side light • Codominant: Top of crown is at upper canopy height; receives full top light, little from sides; medium-sized crown, usually somewhat crowded on its sides. Often wide range around “average canopy” tree. • Intermediate: Top of crown is below the top of the general canopy; receives some top light from directly above, none from the side; conspicuously narrower, smaller and shorter than the average crown. • Overtopped: Crown entirely below some foliage of the upper canopy; receives no direct top light; small, weak crown with low vigor

31. Crown Classification Overtopped http://www.extension.umn.edu/distribution/naturalresources/images/3473-12.jpg

32. Understory Reinitiation: • Mortality of individuals cannot be closed by adjacent individuals • Crowns of trees are now large enough so that when one overstory tree dies, the surrounding trees can not fill the gap • Permanent canopy gaps form • Permanent understory forms • Tree reproduction becomes re-established beneath parent stand • Primary factors influencing species composition • Understory light availability • Species degree of shade tolerance

33. Old-growth/Complex Stage: • Natural mortality of large overstory trees produces irregular canopy gaps • Mortality and recruitment and are in balance and biomass is stable • Can mark transition from an even-aged to an uneven-aged stand

34. Stand Initiation Stem Exclusion Old growth (Complex Stage) Understory Reinitiation

35. Johnson, P.S., S.R. Shifley, and R. Rogers. 2002. The Ecology and Silviculture of Oaks. CABI Publishing, New York, NY. 503 p. Stand Development in the Central Hardwood Region Stand Initiation Phase: 10 – 20 years

36. Johnson, P.S., S.R. Shifley, and R. Rogers. 2002. The Ecology and Silviculture of Oaks. CABI Publishing, New York, NY. 503 p. Stand Development in the Central Hardwood Region • Stem Exclusion: • Begins after 10 years • Concludes before age 70

37. Johnson, P.S., S.R. Shifley, and R. Rogers. 2002. The Ecology and Silviculture of Oaks. CABI Publishing, New York, NY. 503 p. Stand Development in the Central Hardwood Region • Understory Reinitation: • Tree reproduction begins to develop under maturing overstory • Begins after age 50, concludes before age 120

38. Johnson, P.S., S.R. Shifley, and R. Rogers. 2002. The Ecology and Silviculture of Oaks. CABI Publishing, New York, NY. 503 p. Stand Development in the Central Hardwood Region • Complex Stage (old-growth): • Oak forest typically require 100 years or longer to reach this stage.

39. Johnson, P.S., S.R. Shifley, and R. Rogers. 2002. The Ecology and Silviculture of Oaks. CABI Publishing, New York, NY. 503 p. Stand Development in the Central Hardwood Region *Assume no significant stand-scale disturbances occur *Actual durations of stages of development vary with species composition, site productivity, and other factors