Transcript National Advanced Silviculture Program

Thanks for Coming
- Your participation and thoughtful questions will
make our presentation more applicable for you and
the rest of the group.
- SAF Continuing Forestry Education Credit.
- sign in and take a certificate of attendance.
Program Outline
- Morning discussion, afternoon outside
- Please understand if we may need to cut
something short to stay on task.
- Can re-start truncated discussions during the
afternoon field session.
- The program is arranged as many loosely related
topics. Bear with us. We will attempt to pull
them together in the end.
Goals for the Day
Dave and Lou’s Goals;
1. Brief overview of 9-week silvicultural training,
2. Translate to the practice of silviculture in Vermont,
3. Facilitate discussion within the forestry community.
We hope your goals are to;
1. Learn something,
2. Tailor presentation to suit your interests,
3. Refresh memories from Undergrad and Grad School,
4. Take part in a larger discussion of Vermont silviculture.
National Advanced Silviculture
Program
Program Background
The goal is to prepare silviculturists to design
prescriptions that meet the Minimum National Standards
for Silviculture Certification.
4 National Modules
1 Local Module
For Region 9 this has been in
Michigan
Project Development and Defense
Ecological
Systems
Inventory/ Monitoring and
Decision Support
Landscape Ecology
in Theory and Practice:
Application to the Study and
Management of Public Lands
Advanced Silviculture
In Southern Hardwoods
National Advanced Silviculture
Program
A great deal of information
Some direct application to Vermont,
but not all
Definitions
Concepts
Discussion
Silviculture (D.M. Smith)
• The art of producing and tending a forest.
• The application of knowledge of silvics in the
treatment of a forest.
• The theory and practice of controlling forest
establishment, composition, structure and
growth.
Vermont Silviculture
The theory and practice of influencing
the establishment, composition,
quality, structure and growth of
forests.
Some have said there should be a clear
statement of responsibility to maintain
ecosystem health
• So what about this definition of silviculture?
• Silviculture is the theory and practice of
influencing the establishment, composition,
quality, structure and growth of forests, while
maintaining or enhancing ecological function.
• Your thoughts?
•
•
•
Is not cookbook
Infinite variation
Must be able to think and assess situations
and be able to improvise and apply
knowledge to complicated situations that
are encountered in the field
Stages of Stand Development (Oliver & Larson)
Stand Initiation
Stem Exclusion
Understory Reinitiation
Old Growth
Stand Initiation
Natural Systems
• Follows major disturbances (wind, fire, wide spread insect outbreaks…)
• Regeneration of open space from seed, sprouts & advance regeneration
• One cohort or age class
• Stage ends when canopy becomes continuous and trees begin to compete
with each other for light and canopy space.
Silvicultural Implications
• Site preparation to favor a certain species
• Shade tolerance can alter future species composition
• Regeneration mechanism advantage
– (sprouts, heavy seed, wind blown seeds, seed bank…)
• Timing of harvest can influence regeneration
• Density ---- too many or too few
Stem Exclusion
Natural Systems
• Closed canopy precludes understory regeneration
• Canopy continues to have one cohort
• Stems compete for space and “self-thinning” occurs (density dependant mortality)
• Species composition is influenced by:
growth rates of tree species, initial crown position, persistence/ tolerance
Silvicultural Implications
• Few if any additional trees will grow into the canopy
• All growing space is occupied with a chance of stagnation
• Harvests can shape the desired condition and composition of the stand
• Density/ spacing influences growth rates
• Canopy gaps small enough to preclude establishment of understory regeneration
Understory
Reinitiation
Natural Systems
• Reproduction occurs under the parent stand
• Crowns are large enough that canopy gaps are not filled by neighboring overstory
trees following mortality
• Allows space for understory trees to grow into the canopy
• More light reaches the forest floor
Silvicultural Implications
• Typically the stand has reached economic maturity
• Understory regeneration will likely become a major component of the next stand
following disturbance.
•The length of this stage can be altered by silvicultural actions
• Shade tolerance should be considered when trying to establish regeneration.
- great time for shade tolerant and mid-tolerant species regeneration
establishment
Old Growth
Old Growth
DEFINED --- Natural mortality of large overstory trees produces irregular canopy
gaps and accelerates the recruitment of reproduction and sub canopy trees into the
overstory and main canopy.
Silvicultural Implications
• Transition from even aged system to and uneven aged condition
• Length of time in this or any stage is influenced by:
species composition, site quality, duration between stand replacing
disturbances, silvicultural treatments
• Most old growth stands are complex but many complex stands are NOT Old Growth!
Successional Theory
Relay Floristics
vs.
Initial Floristics
Relay Floristics
A model of succession in which species colonize
sites in sequential waves. The first wave of
colonizers is replaced by the second wave, and
so on, until a climax community is established.
Example: Aspen, Paper Birch, Cherry, followed
by Red Maple, White Ash, White Pine, followed
by Sugar Maple, Beech, Hemlock.
Initial Floristics
Most species present in the late stages of stand
development, are able to colonize the site soon
after disturbance. Some species may take early
advantage, or be slower to develop, or have
different natural life spans, but they are all there
at the beginning.
Successional Pathway
Successional pathway is not pre-determined.
A “sugar maple site” could theoretically go to sugar
maple in each successional model, but sugar maple
is not guaranteed.
Beech could occupy that same site for an extended
period, IF during stand initiation, sugar maple was
not established, or if it was established, but was
then suppressed (deer browse) and lost.
Current Thinking
• Both relay floristics and initial floristics occur in
the development of a forest.
• Initial floristics is considered the more
common pattern following disturbance.
• Successional path is not pre-determined.
Multiple successional pathways are possible,
depending on the timing, size and nature of
the disturbance, and the presence/absence of
established regeneration or seed to colonize
the open growing space.
Natural Range of Variability
•Typical disturbance agents in New England
--Wind, ice, insects, fungal pathogens, beaver, flooding, fire
• 1 -3% of northern hardwood forest were in the seedling/sapling stage
historically
• Vermont was 80 – 90 % farm land at the turn of the last century
• 2001 FIA data shows seedling/sapling stage at 16% across the
northeast (4% in MA to 25% in ME)
We are managing a forest that is outside
its natural range of variability.
Wind Event Return
Intervals
Tornados 1950 - 2003
New England Resources
Climate Change
• Higher CO2 results in more trapped heat
throughout the system (greenhouse effect),
• Oceans are warming,
• Polar ice is melting,
• Sea levels are rising.
• Climate is changing and this affects different
places in different ways.
• Some regions will receive more precipitation, some less, and it may
come at different times of the year and in different forms.
• Much of our rain is expected to come in heavy downpours.
All regions will warm, but some will warm more
rapidly than others.
Climate Change in Vermont
• Less snow, more mixed precipitation
(rain/sleet/ice).
• Shorter Winters, less extreme cold (snow as
climate switch).
• More precipitation in Winter, Spring and Fall.
• Less precipitation in Summer (drought).
• More severe precipitation events.
• Damaging winds more common.
Climate Change Impacts in Vermont
• Change is slow, but the rate of change is
increasing, and the impacts are widespread.
• Changes in growing conditions result in
changes to the competitive balance between
species.
• Not all bad. Some species are “winners”
even while others are “losers”.
Silvicultural Considerations of
Climate Change
• Invasive Plants, Insects, Disease, Earthworms.
• Regeneration difficulties with certain species
(sugar maple).
• Decline of species results in more loss,
salvage, lower quality (balsam fir).
• Operational difficulty. Warmer Winter, severe
storms, wet springs, more drainage measures
required.
More to think about
• Warmer temperatures result in a longer
growing season.
• More CO2 results in “CO2 fertilization”.
Increased photosynthesis?
• Photosynthesis: CO2 + Water => sugar + O2.
• Sunlight, leaves and Co2 plentiful, but lack of
available water may limit the ability of trees to
fully utilize the longer growing season.
What Impacts Available Water?
• Total annual precipitation. Yes, but not the
whole story.
• How and when moisture enters the system
(gentle rain, snow melt, heavy rain) matters.
• Soil O.M. (forest floor and humus).
• Soil texture (sand, silt, clay).
• Soil depth (storage, aeration, rooting depth).
Soil Organic Matter
• Forest Floor
–
–
–
–
Contains nutrients.
Moderates temperature (reduces evaporation)
Reduces soil compaction (pore space holds water and O2)
Slows runoff from heavy rains and thus results in greater
percolation into soil, and longer water residence time.
• Soil Humus - holds water and nutrients.
• O.M. is important to the retention of available water.
• All O.M. eventually decomposes, cycles through other
organisms and ultimately returns to the atmosphere as
Co2.
• O.M. cycle. We influence inputs (snags, logging debris) and
outputs (size, temperature affect decomposition rates).
Forest Type Shift
Year 2000
Year 2100
Spruce Fir
Forest
http://www.fs.fed.us/nrs/atlas/
Spruce Fir
Forest
?
Year 2000
Balsam Fir
Year 2100
http://www.fs.fed.us/nrs/atlas/
Year 2000
Sugar Maple
Year 2100
http://www.fs.fed.us/nrs/atlas/
Year 2000
Northern Red Oak
Year 2100
http://www.fs.fed.us/nrs/atlas/
Photosynthate Prioritization
•
•
•
•
•
•
Maintenance respiration
Foliage and fine root growth
Primary growth (height, lateral crown)
Secondary growth (diameter)
Reproduction *
Protection *
* The order of reproduction and protection may
change based on environmental factors
Silvicultural Systems
Broad: Even-Age Management
Narrow: Even-Age Management of
Northern Hardwoods in the Northeast
Silvicultural Systems
A program for treating a type of stand through a full
rotation, or other management cycle.
Expressions of a person’s or persons’ silvicultural vision.
They are sets of recommendations. Guides.
They can and should evolve over time.
There is plenty of room for personal or regional variation.
Even-aged
Management in
Vermont
(one or two age classes)
- The stand is the management unit, rather than individual trees.
- Stands are grown to their “rotation” age.
- intermediate thinning, and regeneration systems that include
shelterwood, seed tree and clearcutting with many variants.
Even-aged
Management in
Vermont
(one or two age classes)
- Simple to implement. The principal problem with this
system is that forests are generally not simple.
- Most effective in stands with uniform growing conditions
and few species
Uneven-aged System: A planned
sequence of treatments designed to
maintain and regenerate a stand with
three or more age classes.
(The Dictionary of Forestry)
Uneven-age Management
may be “Balanced” or “Irregular”
Balanced Uneven-age Management
• Reverse-J diameter distribution is generally assumed to
approximate the natural condition of uneven-age
stands. (incorrect assumption)
• “Balanced” means that each diameter class consists of
the same portion (BA) of the stand.
• Q-value is the logarithmic slope of the TPA in
successive diameter classes. Slope is assumed to be
constant across all diameter classes.
• Diameter distribution and current q-value are
determined from point sampling data.
• Desired q-value is subjective.
• Higher q-value means fewer large trees.
• BDq method.
Balanced Uneven-age Management
Continued
• Group selection, 1/20 to 2 acres in size (NE-603).
• Regeneration is often a goal at each entry.
• Mixing of “size” and “age”. Diameter classes
assumed to be equivalent to age classes.
• Sampling intensity: is approx. a point every 5
acres for small UVA ownerships. Lower (much
lower?) sampling intensity on large, industrial,
State or Federal ownerships.
• Does our data provide us the information to
practice balanced uneven-aged management?
• Why would we want to?
Irregular Uneven-age
management
• Must maintain three or more age classes.
• Not necessary to balance diameter classes.
• Flexible diameter distribution, with greater
emphasis on growing individual trees.
• Maximum group size is flexible.
• Regeneration not considered necessary at
each entry. Only when necessary to maintain
three or more age classes.
Management Units
Even-age mgt: the Stand (Age Class)
Balanced uneven-age mgt: Diameter Classes
Irregular uneven-age mgt: Individual Trees
Multi-Age Crop Tree Management
• Must maintain two or more age classes.
• Not necessary to balance diameter classes.
• Emphasis is on growing individual crop trees to
full term.
• Maintain complexity of forest structure.
• Regeneration matters but is not considered
necessary at each entry. Only necessary to
maintain full stocking with two or more age
classes.
• BDSQ method.
Two – Aged Systems and
Deferment Harvests
•
•
•
•
Grow large diameter sawlogs and veneer
Maintain growth in two size classes
More structurally diverse
Maintain seed source on site to “life boat”
desirable species
Two – Aged Systems and
Deferment Harvests
Considerations:
• Loss of initial revenue from traditional
clearcut
• Overstory still influences the regeneration
• Expected life span of overstory trees
• Ease of operations at next entry
• Silvicultural goals being met?
Two – Aged Systems and
Deferment Harvests
How To:
• Following regeneration establishment
remove overstory trees to 10 -15 ft2/acre
• Retain long lived species with good crowns and vigor
• Pay attention to microsites to avoid wind throw and
other disturbances
• Protect reserved trees during harvesting operations!
• Let them grow for another rotation!
What really matters?
• Model the managed system after the natural
system as much as possible.
• Manage for quality rather than quantity.
• Manage for a healthy forest rather than solely for
a single species, product, age or diameter
distribution.
• Manage for complexity rather than simplicity, but
define complexity in simple terms.
• That is, strive for forest complexity, not
management complexity.
Regeneration
A silvicultural issue in most regions of
the country.
Tennessee/Kentucky – want to
regenerate oaks, but have problems
with more shade tolerant competition.
Oak Regeneration Method
“Shelterwood” Method
Mid-story removal near the rotation end.
20% reduction with little canopy break.
Enough diffuse light to keep established oak
growing.
When sufficient advance regeneration is
present, release with partial or full OSR.
Sugar Maple Regeneration Method
• Do we have one?
• Here is a possibility.
• Maintain high enough early stocking to inhibit the establishment of
competing regeneration while still maintaining growth of the
dominant trees. Maybe 80 sq.ft./acre.
• When the understory begins to re-initiate, and it is composed of
more tolerant competitors, treat them. (Jeff Springer)
• When we must break the canopy in order to maintain growth of our
best crop trees, reduce stocking to 60-70 sq.ft./ac. to release a
wave of established sugar maple.
• When desirable regeneration is established, do subsequent
harvesting to release and advance the regeneration. Winter only.
• At the junction of desired diameter and vigorous, advance
regeneration, implement group selection.
Common Theme
• Oak/Sugar Maple
• Maintain high early stocking to inhibit any
regeneration.
• Control more tolerant regeneration.
• When it is time to regenerate, establish the light
conditions that most favor the target species.
• Protect the regeneration and keep it growing.
• Ultimately release it when the mature overstory
is harvested.
Crop Tree Release
• Common practice in other regions
• 76% of stand value in best 30 T/A (upland
hardwoods, U.Tenn.).
• 98% of stand value in best 60 T/A (upland
hardwoods, U.Tenn.).
• 25% of harvest value in 4% of harvest volume
(Vermont: Paganelli)
Principles of Release
• Early release is preferable to late release
• Release may occur in stages
• Strive for eventual, full release, where
possible.
• S, W, E release is more effective than N
• Growth lag results from late release
– Partly crown-building
– Partly leaf replacement as sun leaves replace
shade leaves
Crown/Diameter/Quality
• Crown size is strongly correlated with available
growing space.
• Diameter growth is strongly correlated with
crown size (photosynthate prioritization).
• Proportion sapwood is very strongly
correlated with crown size. When crown
begins to recede, heart wood expands.
• Particularly important to remember with
sugar maple.
Pruning Theory
• Pruning is most effective in young, fast-growing
trees with small branches.
• Bottom third of the crown more for insurance
against top breakage than growth.
• Lower branches are so inefficient that pruning
sometimes provides a growth response.
• Branch collar wounding increases size of pruning
wound, but also results in faster occlusion.
• Pruning closer to the trunk (not flush cut)
increases the amount of clear wood, with no
evidence of additional decay.
More on Pruning
• Most rapid diameter growth occurs at the
base of the live crown.
• Form class improves as the crown moves up
the tree.
• Prune softwoods to 17 feet.
• Prune hardwoods to 12-14 feet.
Hardwood Release & Pruning
Multi-Stage Technique
• Early release in stages. Age 20-30. Two to three
release cuts 3-5 years apart.
• Early corrective pruning (low, narrow forks)
• Prune trunks to 12-14 feet (veneer (8-12)target).
• Follow to pick up any epicormic branches.
• 60-80 T/A on roughly 20-30 feet spacing.
• Minimize equipment entries. Girdling, cut/leave.
• Target is rapid diameter growth on high-quality
first log.
Potential?
• 60 veneer logs/acre.
• Mix of 10-feet and 12-feet logs, 18-inch dib,
one log/tree.
• 150 bf/log.
• 9 mbf/acre veneer.
• $5,000/mbf mill price.
• $4,500/mbf stumpage price.
• $36,000/acre, plus associated logs/pulp.
Take Home Messages
We have the option to develop local
silvicultural systems, and we should.
Climate change and invasive species will
change our forests and change how we
practice forestry.
Pruning Practices should be re-evaluated.
There is significant potential for value
growth associated with localized intensive
management.