Forestry Exam 3

Tending

Intermediate treatments
A treatment after regeneration but before a final harvest to facilitate the growth of selected crop trees by providing or concentrating resources and manipulating carbon allocation.

Tending Examples

Fertilization
Thinning

Crop tree release

Pruning

Sanitation and Salvage cutting

Prescribed burning

Fertilization as Tending

Accelerates growth for a greater return/time but at a lower wood density and strength

Fertilizaiton Mechanism of Action

Improved resource availability

Increase photosynthesis per leaf area

Increase leaf area index

Carbohydrate Deficit View of Priority

Ion gradients
Protein turnover

Lipid turnover

Growth

Storage

Defense

Reproduction

Maintenance items

Ion gradients

Protein turnover

Lipid turnover

Carbohydrate Surplus View of Priority

Ion Gradients

Protein turnover

Lipid Turnover

Growth

Reproduction

Exudation

Storage

Defense

Carbohydrate Disposal Item

Exudation

Storage

Defense

Thinning in a phrase

Improves the availability of both light and soil-derived resources which facilitates growth

Live Crown Ratio (LCR)

Percentage of live crown to the total height of tree

Importance of LCR

Diameter growth, taper and knots

LCR < 30%

Substantial decrease in diameter growth

LCR <20 %

Causes declines in heigh growth and can reduce response to thinning

Wood Quality and Thinning

Treatments that increase diameter growth increase proportion of late wood
Larger/straighter trees are more valuable
Balance crown size with stem production

Wood Strength

Increases from the pith outward and from the top down
Produced later in life is stronger due to stronger structural demands of later life

Biomass Response to Thinning

Thinning produces more useful wood but not more wood overall

Pulpwood Requirements

Minimum DBH: 4”
Merchantable Height: 16’ to a 4” diameter
Relatively straight

Thinning Products Objective

Redistribution of growth on fewer stems

Thinning Form Objective

Produce more cylindrical trees
Initial increase in stem taper is short-lived and tendency towards cylinder returns

Thinning Economic Objective

Supplies an intermediate source of income
Longer rotations means bigger trees means more income

Thinning Biological Objective

Modify stand composition
Thinned stands have greater vigor and make better seed producers
Withstand wind better

Commercial thinning

Harvesting of commercially valuable mature trees, usually pulpwood
Basal area exceeds 100 sq. ft/acre
Lower BA to 70-80 sq. ft/ acre

Pre-commercial Thinning

Cutting of small trees in immature stands
If young trees spaced closely
Removed individually or entire rows
Cost generator with no immediate benefit

Low Thinning

“German” method; “thinning from below”; “ordinary” method
Mimics an accelerated rate of natural mortality
All trees short or smaller than a given standard are cut
Not much effect on remaining trees so is appropriate when nearly all trees are merchantable

Thinning Grades

B - Light
C - Moderate
D - Heavy

Crown thinning

“Thinning from above”; “high thinning”; “French” method

Trees removed from upper and middle part of crown
Remove co-dominants
Remove any trees impacting crop trees
Intermediate trees “train” dominants by reducing the amount of the limbs they can grow

Selection Thinning

Removal of select dominants to stimulate growth of lower crown classes
High grading used
Removing poorly formed dominants
Susceptible to wind damage

Geometric Thinning

Row or mechanical thinning
Predetermined removal of limbs
Usually every 3rd row removed and remaining rows are thinned selectively

Timing of First Thinning

Balances trade off between diameter growth and self-training with economics in mind

Crop Tree Release (CTR)

Similar to crown thinning with focus on crop trees
Eliminate competition of crop trees from at least three sides
Concerned with competition within the canopy

Salvage & Sanitation cutting

Used to eliminate infected trees
Removes the non salvageable and the infected
Sanitation leaves dead trees where as salvage does not

Pruning

Improves wood quality, reduces crown fire hazard, improves disease resistance but does not increase tree growth

Density

Number of trees per acre

Stocking

Assessment of density relative to a standard and derived from density-dependent morality

Regeneration Approaches

Natural
Artificial

Natural Regeneration Approach

Low initial cost and maintenance 

High risk

Variable return

Longer harvest cycles

Good for marginal land

Ecologically diverse and balanced

Artificial Regeneration Approach

High investment and maintenance

Medium risk

High return

Shortened harvest cycles

Needs high site quality

Monoculture

Unaccounted environmental costs

Regeneration Types

Sexual
Clonal

Natural Regeneration Steps

Seed supply

Ensure seed dispersal

Germination

Early survival