Transcript Forest Management & Regeneration

Forest Management &
Regeneration
All forest management has
regeneration consequences in
northeastern forests
Susan L. Stout
Research Silviculturist
Northern Research Station
USDA Forest Service, Irvine, PA
This is NOT a regeneration
webinar
• We’ll discuss partial
cutting practices
– Principles
– Benefits
– Strategies
• And their implications
for regeneration
• Linked to a later
webinar on treating
some problems partial
cutting might cause
Scope
• Examples and data will be from
naturally regenerated mixed
northeastern hardwood forests,
primarily in PA
• Emphasis on even-aged forests
• Principles apply more generally to
mixed forests where natural
regeneration methods are used
With a little help from my
friends…
• Todd Ristau
• Ruth Yanai
• Dave Marquis
• Mark Twery
• Ben Roach
• Ralph Nyland
• Chris Nowak
• Dave Jackson
• Jim Finley
• and others
Principles of Silvicultural Partial
Cutting
• Concentrate
growth on the
best trees
• Salvage mortality
• Reduce rotation
• Influence species
composition
These principles apply to both even- and uneven-age stands
EFFECT OF DENSITY
on TREE & STAND GROWTH
Vol. Growth - Cu. Ft. / ac / yr
Stands
Trees
75
1.5
50
1.0
25
0.5
0
0.0
0
20
40
60
Relative Density - %
80
100
Dia. Growth - in. / 5 yr.
2.0
100
Relative Density?
• Similar to “stocking”
• Relative to the basal
area and #
trees/acre found in
unmanaged stands
• Expressed as a
fraction of 100%
EFFECT OF DENSITY
on TREE & STAND GROWTH
Vol. Growth - Cu. Ft. / ac / yr
Stands
Trees
75
1.5
50
1.0
25
0.5
0
0.0
0
20
40
60
Relative Density - %
80
100
Dia. Growth - in. / 5 yr.
2.0
100
Open-Grown Trees
• Individual tree
growth is at
maximum level
• Widely spaced trees
unable to “fully
occupy” growing
space
georgiachronicles.files.wordpress.com/2009/03
.
EFFECT OF DENSITY
on TREE & STAND GROWTH
Vol. Growth - Cu. Ft. / ac / yr
Stands
Trees
75
1.5
50
1.0
25
0.5
0
0.0
0
20
40
60
Relative Density - %
80
100
Dia. Growth - in. / 5 yr.
2.0
100
Basic Concept
• Above some
threshold density of
trees, a particular
piece of land is
going to produce a
certain amount of
wood per year
• The idea underlying
thinning is that YOU
can choose whether
that wood is spread
over a large number
of small trees or a
smaller number of
soon-larger trees of
your choice in
species and quality
Moderate stand density
• Optimal trade-off between
individual tree growth and
stand growth
• Actual density considered
moderate varies with
species composition
• Economics vary with
markets and large product
premiums
EFFECT OF DENSITY
on TREE & STAND GROWTH
Vol. Growth - Cu. Ft. / ac / yr
Stands
Trees
75
1.5
50
1.0
25
0.5
0
0.0
0
20
40
60
Relative Density - %
80
100
Dia. Growth - in. / 5 yr.
2.0
100
Dense stands
• Mortality high
among smallest
stems
• Individual tree
growth low
• Maximum control of
understory light
EFFECT OF DENSITY
on TREE & STAND GROWTH
Vol. Growth - Cu. Ft. / ac / yr
Stands
Trees
75
1.5
50
1.0
25
0.5
0
0.0
0
20
40
60
Relative Density - %
80
100
Dia. Growth - in. / 5 yr.
2.0
100
EFFECT OF DENSITY
on TREE & STAND GROWTH
Vol. Growth - Cu. Ft. / ac / yr
Stands
Trees
75
1.5
50
1.0
25
0.5
0
0.0
0
20
40
60
Relative Density - %
80
100
Dia. Growth - in. / 5 yr.
2.0
100
RED MAPLE MORTALITY
30
Mortality - % 5 yrs
25
20
15
Supressed
Intermediate
10
5
Dom. and Codom.
0
40
50
60
70
Relative Density - %
80
90
100
200
2.0
150
1.5
100
1.0
Basal Area
50
0.5
Bdft Volume
0
40
60
80
Relative Density - %
100
0.0
Mortality - Sq. Ft. /ac. / yr
Mortality - Bd. Ft. /ac. / yr
MORTALITY
NET GROWTH
4
300
Bdft Volume
3
200
2
Basal Area
100
20
1
40
60
80
Relative Density - %
100
Growth - Sq. ft. / ac. / yr.
Growth - Bdft / ac. / yr.
400
EPICORMIC BRANCHING
Trees with Epicormics - %
30
20
10
0
20
30
40
50
60
Relative Density - %
70
80
90
Residual density is a
COMPROMISE
among
Stand growth, tree growth, tree
quality, and understory response
Promote stand
development
• Enhance habitat for plants and
animals
• Alter visual qualities
• Move toward old growth (big
tree) conditions
Enhance habitat
• Openness in
canopy, especially
later in stand
development,
desirable for some
wildlife species
– Some bats
– Some birds – e.g.
Cerulean warblers
Google Image
Alter Visual Qualities
Before
After
Accelerate development of
“big tree” condition
• Thinning can
promote faster
tree growth
regardless of
management
objective
When to thin
• The younger the stand, the more
responsive it will be
• General recommendation is to make a
first thinning as soon as it can be made
commercially – that varies with markets,
especially fiber (or biomass?) prices
How to thin after Nowak
1997
How to Thin II
• Primarily from below
• Pay attention to
saplings – may need
to treat them in
young stands
• About 1/3 of cut in
main crown canopy
to favor best trees
Allegheny hardwoods
• Annual net growth after
Nowak 1996
• Highly variable, with
maximum from ~70 to
~110 ft3 / acre / yr
• In older stands, pattern is
same but response is less
• The more cherry, the
greater the growth
Mixed Oaks
• After Dale and
Hilt 1989
• Shows cumulative
benefit of thinning
• SI 65 grows about
50 ft3 / acre / yr
Stand development
Stand Establishment Stem Exclusion
After Kimmins 1987, Oliver and Larson 1990
Understory Reinitiation
Old Growth
Stand development
Stand Establishment Stem Exclusion
After Kimmins 1987, Oliver and Larson 1990
Understory Reinitiation
Old Growth
Regeneration Effects
During Stem Exclusion
• Trees very
responsive
• Canopy closure
occurs quickly
• Overstory can
maintain control of
site
• If thinning leaves
best trees and is not
too heavy
Shade Tolerant, Slow
Growing Species
Grow extremely well in partial shade; resilient to deer browsing; shade out
other regeneration
Hay-scented and NY Fern
• HS & NY fern have
a dichotomous
forking rhizome. In
partially cut stands
the rhizome grows
faster and produces
rhizome buds which
grow out rapidly
Invasives
• An emerging
problem associated
with partial cutting –
e.g. Ailanthus
• Very important to
recognize and
address invasives
with every entry
Seed Source
• All partial cutting
has potential to
change species
composition
• Important to retain
seed source for all
species desired in
next stand, even in
early thinnings
Stand development
Stand Establishment Stem Exclusion
After Kimmins 1987, Oliver and Larson 1990
Understory Reinitiation
Old Growth
Understory Reinitiation
• Older trees less
responsive
• Takes longer to
regain crown
closure
• Risk of creating or
worsening
understory problems
is greater
Forest Management &
Regeneration
• Many benefits associated with partial
cutting in mixed hardwood forests
• All these benefits come with risks
related to regeneration
• Careful practice – thin from below, don’t
thin too much – reduce this risk
• Conserving desirable seed source also
very important
But what if you end up with
these problems anyway?
• Dave Jackson Webinar February 9th
• Regenerating Hardwood Stands:
Managing Competition, Deer, and Light
Bibliography
•
Hyperlinks will take you to TreeSearch, a one-stop on-line source
for research publications produced by US Forest Service
scientists.
•
Roach, Benjamin A. 1977. A Stocking Guide for Allegheny Hardwoods
and Its Use in Controlling Intermediate Cuttings. Res. Pap. NE-373.
Upper Darby, PA: U.S. Department of Agriculture, Forest Service,
Northeastern Forest Experiment Station. 30p.
•
Roach, Benjamin A.; Gingrich, Samuel F. 1968. Even-aged silviculture
for upland central hardwoods. Agric. Handb. 355. Washington, D.C.:
U.S. Department of Agriculture, Forest Service, Northeastern Forest
Experiment Station. 39 p.
•
Stout, Susan Laurane; Nyland, Ralph D. 1986. Role of species
composition in relative density measurement in Allegheny hardwoods.
Can. J. For. Res. 16:574-579.
Bibliography (Cont.)
•
Marquis, David A.; [Editor] 1994. Quantitative silviculture for hardwood
forests of the Alleghenies :
Thinning/Distribution/Marketing's/Principles/Summary. Gen. Tech.
Rep. NE-183. Radnor, PA: U. S. Department of Agriculture, Forest
Service, Northeastern Forest Experiment Station. 247-376 p.
•
Yanai, Ruth D.; Twery, Mark J.; Stout, Susan L. 1998. Woody
understory response to changes in overstory density: thinning in
Allegheny hardwoods. Forest Ecology and Management. 102: 45-60.
•
Nowak, Christopher A.; Marquis, David A. 1997. Distribution-of-cut
guides for thinning in Allegheny hardwoods: a review. Res. Notes NE362. Radnor, PA: U.S. Department of Agriculture, Forest Service,
Northeastern Forest Experiment Station. 7 p.
Bibliography (Cont.)
•
Nowak, Christopher A. 1996. Wood volume increment in thinned, 50to 55-year-old, mixed-species Allegheny hardwoods. Canadian
Journal of Forest Research 26: 819-835.
•
Hilt, Donald E.; Dale, Martin E. 1989. Thinning even-aged, upland oak
stands. In: Hutchinson, Jay G., ed. Central hardwood notes. St. Paul,
MN.: U.S. Dept. of Agriculture, Forest Service, North Central Forest
Experiment Station. 6.06.
•
Kimmins, J.P. 1987. Forest ecology. New York. MacMillan.
•
Oliver, Chadwick Dearing; Larson, Bruce C. 1990. Forest stand
dynamics. New York: McGraw-Hill. 467 p.