Presentations text content in Stand Density Basic Concepts
Forest Stand Dynamics
are the product of past disturbances and management. Understanding how some
(for example, fire, harvest, etc.) history has influenced
or how it changes and develops in the future (that is, forest stand
may want to evaluate different management regimes to see how differentiation, the divergence in growth patterns of individual trees, affects the stand structure in terms of
or how it might influence stand and stock tables.Slide4
: trees whose crown extends above the general level of the main canopy of even-aged stands, or in uneven-aged stands, above the crowns of the tree's immediate neighbors and receiving full light from above and partial light from the sides.
: a tree whose crown helps to form the general level of the main canopy in even-aged stands, or in uneven-aged stands, the main canopy of the tree's immediate neighbors, receiving full light from above and comparatively little from the sides.
: trees with crowns either below or extending into the canopy formed by
and dominant trees; receiving little direct light from above and none from the sides; usually with small crowns considerably crowded on the sides.
: trees with crowns entirely below the general level of the crown cover receiving little or no direct light from above or from the sides
Growth and Yield
is the change in
volume, weight or
other characteristic of interest over a specified time period
is the existing amount of that characteristic of interest for a particular type of forest stand by species, site, stocking, and management regime at a specified point in
Growth and Yield
, let's say your stand of slash pine might increase in volume by 2,000 cubic feet over 10 years. If we state this as an annual increment, we would say that the stand's growth is equal to 200 cubic feet per year (2,000 cubic feet per year / 10 years).
actually has 2 meanings. It is
amount of some characteristic that can be harvested per period, or
the total amount that could be removed at any timeSlide8
Organism and Population Idealized Growth CurveSlide9
Current (CAI) – the increment over a period of one year at any stage in a tree’s life
MAI = yield @ age A/Age A
PAI = Yield @ age A
– Yield @ age A
– age A
PAI = sum of CAI from age A
Age X MAI
Sum of CAI from 0 to Age ASlide12
It is all about the LeavesSlide13
Leaf Area IndexSlide14
Stand Density Index
A measure of
the stocking of a stand of trees based on the number of trees per unit area and diameter at breast height of the tree of average basal
Stand Density Index
N + 1.605 log
D - 1.605
Example: Given BA = 150
and N = 400 trees per acre, the QMD =
SDI = log
(400) + 1.605log
(8.29) - 1.605 = 2.47
SDI = 10
BA used instead since easier to calculate and well-correlated to SDI
3/2 Law of Self-Thinning
For pure even aged stands crowded to the point of self thinning the mathematical relationship exists
Log (mean tree volume) = -3/2 log (tree density) + C
C is a constant that varies by species
Mathematically equivalent to SDISlide17
Maximum Crown Area
A – unit area (43560 ft
or 10000 m
= number of trees per acre
= average Height of the dominant canopy in feet
Crown Competition Factor
Measure of stand density
Independent of site quality, stand age, stand structure (even or uneven-age stands)
Definition: Area available to the average tree in a stand compared to the maximum area used by an open-grown tree with the same diameter
Crown Width (CW) vs. DBH – linear relationship
Maximum crown area (MCA): crown area of an open-grown tree of diameter DBH, expressed as % of unit area (1 ac or 1 ha)Slide21
Crown Competition FactorSlide22
Harvesting, Regeneration and Thinning
- the main regeneration method is vegetative sprouting of either suckers (from the existing root system or cut
or shoots (from cut stumps).
- a regeneration method designed to regenerate and maintain a stand with a single age class and includes:
- the cutting of essentially all trees, producing a fully exposed microclimate for the development of a new age class.
- an even-aged regeneration method in which selected trees (seed trees) are left standing after the initial harvest to provide a seed source for
. Seed trees can be left uniformly distributed or in small groups. Although regeneration is generally secured naturally, it may be augmented by planting. Seed trees are often removed once regeneration is established or may be left as reserves.
- a regeneration method in which trees are removed as a series of cuts designed to achieve a new
under the shelter of remaining trees
- a regeneration method designed to regenerate and maintain a stand with two age classes, usually through the retention of reserve trees in the
- (also known as selection methods) a regeneration method designed to create or maintain and regenerate an
single tree selection
- a regeneration method in which individual trees of all size classes are removed more or less uniformly throughout the stand to promote growth of regeneration.
- a regeneration method which removes trees and facilitates regeneration in small groups.Slide24
thinning from below
- (also known as ordinary, German, or low thinning) the removal of trees from the lower crown classes to favor those in the upper crown classes.
thinning from above
- (also known as French or crown thinning) the removal of trees from the dominant or
crown classes to favor the best trees of those same crown classes.
- the removal of trees from the upper crown classes to favor trees in the lower crown classes.
- (also known as mechanical or geometric thinning) the removal of trees in rows, strips, or using fixed spacing intervals.Slide25
Released by thinningSlide26
Fire and Fuels Management
may be interested in decreasing
To do so,
to understand the fire types such as
fires and their effects on stands
want to look
at stand attributes such as
canopy bulk density
This information can help predict fire types and spread so they can be managed or prevented.
Thinning reduces and redistributes fuel loads thus fire hazards.