FOR 350 Lectures 11-13_2011 Students

Document Sample
FOR 350 Lectures 11-13_2011 Students Powered By Docstoc
					              Concepts of Regeneration

•   Regeneration vs. reproduction

•   The primary focus of harvest must be regeneration
                  Concepts of Regeneration

•       Key goals of a regeneration program:
    –     Make the results predictable

    –     Affect species composition
           Concepts of Regeneration

–   Appropriately stock the site with desirable species

–   Set the stage for future management

–   Minimize the chance of failure
            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
         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
            Concepts of Regeneration

•   Origin of reproduction
                   Concepts of Regeneration

•       Categories of reproduction
    –      New seedlings:

    –      Advance reproduction:

    –      Stump sprout:

    –      Root suckering:
Stump Sprouting Probability by Age and Species

                                  Tree Age
                Regeneration Process
              (its all about species silvics!)

•   New forest communities establish whenever three
    conditions develop:
               Concepts of Regeneration

Seed Supply
•   Flowering and seed production
                Concepts of Regeneration

Seed dispersal
•   Reproductively mature trees within dissemination range required for
    regeneration from seed

•   Factors influencing seed dissemination (i.e., dispersal)
• Seed dispersal distance is species dependent
            Concepts of Regeneration

Seed bank

  • Viability and germination stimuli various among species
               Concepts of Regeneration

Seed Bed and Germination
•   Physical characteristics of forest floor affect germination

•    Position of seed within the seedbed affect predation and
     germination rates
•    Light, temperature, and moisture affect seed viability and
               Concepts of Regeneration

• 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)
Species of the Central Hardwood Region

       Species            Seed Dissemination
                          Gravity   Animals    Wind
       Yellow-Poplar                             X
       White Oak              X        X
       Chestnut Oak           X        X
       Black Oak              X        X
       Northern Red Oak       X        X
       Scarlet Oak            X        X
       Sugar Maple                               X
       Red Maple                                 X
       Pignut Hickory         X        X
       American Beech         X        X
              Concepts of Regeneration

•   Established Seedlings
Shade Tolerant and the Understory Environment
 – Tolerant :

 – Intermediate:

 – Intolerant:
Influence of Light Availability on Seedling Photosynthesis
Relationship between Available Sunlight and Stand Structure
Relationship between Canopy Cover, Available Sunlight, Understory

  • Optimal level dependant on species shade tolerance and growth
Species of the Central Hardwood Region

     Species            Shade Tolerance
                          Intolerant      Intermediate   Tolerant
     Yellow-Poplar            X
     White Oak                                 X
     Chestnut Oak                              X
     Black Oak                                 X
     Northern Red Oak                          X
     Scarlet Oak              X
     Sugar Maple                                            X
     Red Maple                                              X
     Pignut Hickory                            X
     American Beech                                         X
                   The Silvicultural System

• Even-aged and Uneven-aged
   – One age class vs. at least three age classes in a stand (an age class is
       defined at 20% of the rotation length)
                The Silvicultural System

• Hybrid Systems
   – Hybrid of even- and uneven-aged.
             The Silvicultural System

• Regeneration methods are classified into distinct
Common Even-Aged Systems


         Seed Tree

•   Clearcutting vs. clearing—Clearcutting is a regeneration
    method, clearing is removing all of the trees for some non-
    forest use

•   Silvicultural clearcuts differ from ‘commercial clearcuts’.
    The first removes all trees, the second only merchantable

•   Clearcutting changes the microenvironment:

•   Edge effect

–   The effect on the hydrologic cycle; increased water yield returns to
    normal within 4 to no more than 10 years following harvest.

–   Where harsh site conditions or silvical characteristics of desired
    species require site amelioration, it can be done by leaving slash on
    site or by switching to some other reproduction method.

•   Clearcutting technically initiates a new age class AFTER
    overstory removal. The new stand comes from:

•   Advance reproduction is often helpful and sometimes a
    necessity in even-aged regeneration of some species, most
    notably oaks.

•       Management of or mitigation of effects of clearcutting
    –      Affect nutrient outflow from harvest by

    –      Rapid regrowth of vegetation will stabilize nutrients on the site
           within 4 years

•       Alternate configurations for clearcutting
    –      Block clearcutting

    –      Alternate strip or alternate patch

•       Alternate configurations for clearcutting
    –      Progressive strip method

•       Alternate configurations for clearcutting
    –      Patch cutting

•   Alternate methods are often used to:
•   Other considerations when using clearcutting or any even-
    aged method

•       Site preparation considerations for natural regeneration

    –      Some important questions

Site preparation and clearcutting: Considerations for natural
   –    Scarification → mineral seedbed

   –    Control slash residues

   –    Mechanical or chemical vegetation control
•   Advantages of the clearcutting method/system
•       Shortcomings of clearcutting with natural regeneration
    –      Problems with dependable seed sources and seedling establishment

    –      Issues associated with no high forest cover and high light

    –      Reduced chance for genetic improvement
•       Shortcomings of clearcutting with natural regeneration
    –      Impacts on soils and hydrology

    –      Decreased visual aesthetics
    –      Increased fire danger
    –      Decreased wildlife habitat for some species
Coppice Silviculture
•   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

•   Typically associated with short rotation production of
    pulpwood or fuelwood

•   Some coppice principles:

•   Coppice for energy, bioremediation, environmental cleanup

•   The cutting cycle is set by when the MAI intersects PAI
•   General shortcomings of coppice systems

•   General shortcomings of short-rotation biomass plantations
Coppice with standards: scattered, individual stems allowed to
grow on through several coppice cycles

Shared By: