FOR 350 Silviculture

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

• Silviculturists (not silviculturalists) operate in the realm of the biologically possible

• Only solutions that are simultaneously biologically possible, economically feasible, and socially acceptable, will be considered appropriate (and sustainable)

To know what is biological possible

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• Silvics is the study of the biological characteristics of tree species and communities including how:

1) Trees reproduce, establish, and grow

2) Physical environment influences their physiology and character

3) Tree communities influence their physical environment and the interaction between vegetation and physical environment as forests change through time

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’

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.

The Silvicultural System

• To meet landowner objectives, silviculturists alter the forest environment by manipulating stand structure

• Required environment is influenced by:

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

The Silvicultural System

• Each silvicultural system should:

Categories of Silvicultural Systems

• Even-aged SystemA 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 SystemA planned sequence of treatments designed to maintain and regenerate a

stand with three or more age classes.

• Two-aged (Hybrid) SystemA planned sequence of treatments designed to maintain and regenerate a

stand with two age classes.

Silvicultural Systems and Methods

• A silvicultural system is named based upon the regeneration method used

• Regeneration methods are classified as follows:

Establishment

An Example: Phases of an Even-Aged System

Benefits• Reduce density• Improve growth and quality• Favor desired species• Shorten rotation

Phases of an Even-Aged System

Intermediate Treatments

Phases of an Even-Aged System

Benefits• Improve germination, survival, and growth of desired seedlings

• Removal of unwanted vegetation and slash

Site Preparation

Benefits• Create conditions require to establish new stand of desired species

Phases of an Even-Aged System

Regeneration Methods

The Silvicultural System

• The choice of a method depends on:

The Silvicultural System

• Modifications of a silvicultural method– Type: apply different kinds of treatments

– Intensity: change the intensity of application

– Timing: alter timing of application

– Sequence: change the sequence of treatments over time

The Silvicultural System

• Modifications often implemented for non-timber considerations:– Size and distribution of regeneration area– – Nature of residual trees– – Amount, kind, and frequency of seed production– – Coarse woody debris left on site (amount, size, and distribution)– Implementation of Best Management Practices (BMPs)

Biologic and economic factors affecting silviculture

• Site quality• Stand character and condition• • Accessibility and terrain•