Oak Regeneration Evaluation

Simulating Regeneration Dynamics in
Upland Oak Stands
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USDA Forest Service
Southern Research Station
Dr. David Loftis
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Regen for Excel is a simulation model that using
rankings of expected postharvest performance
to predict species composition of dominant and
codominant trees twenty years following
complete overstory removal
USDA Forest Service
Southern Research Station
Dr. David Loftis
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USDA Forest Service
Southern Research Station
Dr. David Loftis
Midstory Present, No Yellow-Poplar Seed Source
Density of Advance Seedling Reproduction by Species and Height Class
(ft) prior to complete overstory removal
Species
Small
(< 2 ft tall)
600
300
Medium
(2 to 4 ft tall)
600
300
Large
(> 4ft tall)
300
0
Total
White Oak
200
100
0
300
Red Oak
A. Beech
Total
300
200
1600
150
150
1300
20
130
450
470
480
3350
Red Maple
Sugar Maple
1500
600
Midstory Present, No Yellow-Poplar Seed Source
Species composition of dominant/codominant canopy trees twenty
years following overwood removal
red maple
8.5%
sugar maple
10.7%
beech
10.3%
northern red oak
70.6%
Midstory Present, Yellow-Poplar Seed Source Present
Species composition of dominant/codominant canopy trees twenty
years following overwood removal
7.1%
red maple
sugar maple
beech
yellow poplar
northern red oak
11.3%
8.6%
7.6%
65.4%
No Midstory Present, Yellow-Poplar Seed Source Present
Density of Advance Seedling Reproduction by Species and Height Class
(ft) prior to complete overstory removal
Species
Small
Medium
Large
Total
(< 2 ft tall) (2 to 4 ft tall) (> 4ft tall)
Red Maple
600
0
0
600
Sugar Maple
300
0
0
300
White Oak
200
100
0
300
Red Oak
300
150
20
470
A. Beech
200
0
0
200
Total
1600
250
20
1870
No Midstory Present, Yellow-Poplar Seed Source Present
Species composition of dominant/codominant canopy trees twenty
years following overwood removal
0.8%
0.4%
red maple
18.7%
sugar maple
0.5%
35.1%
beech
yellow poplar
white oak
northern red oak
44.4%
Shade tolerant understory and midstory trees removed,
Yellow-Poplar Seed Source Present
Density of Advance Seedling Reproduction by Species and Height Class
(ft) prior to complete overstory removal
Species
Small
Medium
Large
Total
(< 2 ft tall) (2 to 4 ft tall) (> 4ft tall)
Red Maple
0
0
0
0
Sugar Maple
0
0
0
0
White Oak
200
100
0
300
Red Oak
300
150
20
470
A. Beech
0
0
0
0
Total
500
250
20
770
Shade tolerant understory and midstory trees removed,
Yellow-Poplar Seed Source Present
Species composition of dominant/codominant canopy trees twenty
years following overwood removal
yellow poplar
white oak
33.3%
northern red oak
62.6%
4.1%
Simulating Regeneration Dynamics in
Upland Oak Stands
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Simulations underscore:
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• Importance of having competitive advance oak
reproduction present prior to final overstory removal
• Role of silvicultural treatments in controlling
competing vegetation and enhancing the competitive
position of oak reproduction
USDA Forest Service
Southern Research Station
Dr. David Loftis
Evaluating Advance Oak Reproduction
• Evaluating the density, size, and species composition of
advance reproduction is a critical step in planning
regeneration systems like the shelterwood
• Successful regeneration of oak species typically requires a
sufficient number of large, well-distributed advance
reproduction prior to overstory removal
• Shelterwood overstory should not be removed until sufficient
oak reproduction has developed.
Evaluating Advance Oak Reproduction
• Two approaches are generally used to evaluate levels of
advance reproduction
– Fixed Radius Plot (i.e. plot count) Inventory
– Stocked Plot Inventory
Evaluating Advance Oak Reproduction
• Fixed Radius Plot (i.e. plot count) Inventory
– Typically completed in conjunction with large tree inventory
• Density of potential stump sprouting oaks determined from
large tree inventory.
– Plot size usually 1/1000 acre (3.72 ft radius) to 1/200 acre (8.33
ft radius)
– Advance reproduction density summarized by species and
height class
Evaluating Advance Oak Reproduction
• Stocked Plot Inventory
– Inventory determines the percentage of plots stocked with an
advance reproduction stem of a specified species and size
– Density of potential stump sprouting oaks determined from large
tree inventory
– Stocked plot percentage is then compared to a predetermined
stocking percent benchmark
• Benchmark indicates the number of stocked plots typically
necessary to result in successful regeneration of the target
species or species group
SILVAH Oak
Brose, Patrick H.; Gottschalk, Kurt W.; Horsley, Stephen B.; Knopp, Peter D.; Kochenderfer, James N.;
McGuinness, Barbara J.; Miller, Gary W.; Ristau, Todd E.; Stoleson, Scott H.; Stout, Susan L. 2008.
Prescribing regeneration treatments for mixed-oak forests in the Mid-Atlantic region. Gen. Tech.
Rep. NRS-33. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern
Research Station. 100 p
SILVAH Oak Regeneration Evaluation
• SILVAH Oak method uses data collected on:
–
–
–
–
–
Desirable seedling regeneration
Interfering plants
Site quality
Overstory shading
Deer impact
SILVAH Oak Regeneration Evaluation
• SILVAH summarizes set of key decision variables
– Variables evaluated against thresholds according to the “stocked
plot” concept
• For any key decision variable, a minimum, per-plot, threshold
has been established and any plot exceeding that minimum
threshold is considered stocked
• Established from research and forestry practice
SILVAH Oak Inventory Method
• Evaluating regenerative potential of mixed-oak stands
must simultaneously consider species present,
abundance, size, and spatial distribution of reproduction,
and factors limiting successful regeneration
• SILVAH uses three nested plots
– Tree regeneration: 6 ft radius plot
– Obstacles to successful regeneration: 26 ft radius interference
plot
– Overstory conditions: 10 BAF prism
SILVAH Oak: Regeneration Plot
• SILVAH simultaneously evaluates regeneration
abundance and size by the “stocked plot” approach
• Regeneration rooted in 6 ft plot is tallied using weighted
counts into ten categories
• Stem counts for the different species groups are
adjusted for size and are recorded as weighted counts
SILVAH Oak: Regeneration Plot
• Competitive Oak: Stump sprouts or stems >3 feet tall OR with a
root collar diameter (RCD) >0.75 inches.
• Established Oak: Count all stems 0.5−3 feet tall OR with RCD
0.25−0.75 inches.
• New Oak: Count all stems <0.5 foot tall and a RCD <0.25 inches
SILVAH Oak: Regeneration Plot
•
Black cherry: Count all seedlings ≥2 inches tall with 2 normal-sized leaves.
Stems > 1 foot tall are counted twice.
•
Yellow-poplar: Same as black cherry. Ignore if oak site index <65.
•
Conifers: Count any hemlock, pine, or spruce seedling with 2 whorls OR
0.5-1 foot tall. Stems w/ ≥3 whorls or >1 foot tall are counted twice.
•
Other desirables: Same as black cherry. Maples must pass the tug test.
For hickory and walnut, count all stems meeting established oak criteria;
stems meeting competitive oak criteria are counted twice.
SILVAH Oak: Regeneration Plot
•
Saplings: If a past disturbance has allowed regeneration to grow into
saplings (1 to 6-inch d.b.h.), tally them if they are a desirable species, have
good form and vigor, and meet one of these density thresholds: two stems
less than 2.0 inches d.b.h. or one stem 2 to 6 inches d.b.h. Record the code
of the dominant species.
•
Residuals: Good quality stems 6-10 inches dbh that are the same age as
main canopy and will be retained after final harvest. Record species code.
•
Tall woody interference: Undesirable species more than 6’ tall rooted in or
near the plot. Record species code of the dominant stem.
SILVAH Oak: Interference Plot
• Interference plot assesses competing vegetation, deer
impact, and site limitations
• Interference plot has 26-foot radius
• One interference plot with each regeneration plot
SILVAH Oak: Interference Plot
Interference plot tally categories:
•
Low Woody Interference: Visually group foliage of shrubs and undesirable
trees less than 6’ tall together. Estimate cover by 5% increments. Record
percent cover and code of the dominant species.
•
Fern (bracken, hay-scented, New York): Estimate percent cover by 5%
increments. For other fern species, report half the cover. If >50% coverage,
record in 10% increments.
•
Grass and Sedge: Estimate percent cover by 5% increments. Record 1%
even if only a trace of grass or sedge is present.
•
Grapevine: Record the number of grapevines rooted in the plot.
•
Site limitations: Record if present anywhere on the plot. 1= poor drainage,
2= rocky/thin soil, 3= thick duff.
SILVAH Oak: Interference Plot
•
SILVAH uses five levels of deer impact to estimate
browsing pressure
–
–
–
–
–
Very low impact
Low impact
Moderate impact
High impact
Very high impact
SILVAH Oak: Overstory Plot
• Inventorying the overstory entails collecting basal area
data by species, diameter, and stem quality.
• One overstory plot for every two regeneration plot
• The inventory can be inventoried using fixed-area or
variable-radius sampling techniques
SILVAH Oak: Key Decision Variables
• Understory Regeneration Stocking
– SILVAH determines regeneration stocking for the species and
species groups
– Number of qualifying stems recorded compared to “stocked” plot
thresholds adjusted for site quality and deer impact
SILVAH Oak: Key Decision Variables
SILVAH Oak: Key Decision Variables
• Oak Stump Sprout Stocking
– An important source of oak regeneration is sprouting of the
overstory oaks after they are harvested
– Sprouting probability of mature oaks varies considerably among
the species and decreases as size class increases
SILVAH Oak: Key Decision Variables
• Oak stump sprout probability
SILVAH Oak: Key Decision Variables
• Oak Stump Sprout Stocking
– SILVAH estimates the number of stump sprouts from overstory
data and sprout probabilities
– Estimated stocking percentages associated with sprout density
SILVAH Oak: Key Decision Variables
• Oak Stump Sprout Stocking
SILVAH Oak: Decision Making
SILVAH Oak uses a series of decision charts to determine
the regeneration status of a stand. The decision chats
use a number of summary variables.
Summary Variables
•
Any Competitive Regeneration:
A plot is stocked with Any Competitive Regeneration if it meets the stocking criteria
for any of the regeneration categories except New Oak, Established Oak,
Established Desirables, and Total Oak
SILVAH Oak: Decision Making
Summary Variables (continued)
•
Any Established Regeneration:
A plot is stocked with Any Established Regeneration if it meets the stocking
criteria for any of the regeneration categories except New Oak and Total Oak
•
All Established Oak:
A plot is stocked with All Established Oak if it meets the stocking criteria for
Established Oak or Competitive Oak
•
All Oak:
A plot is stocked with All Oak if it meets the stocking criteria for New Oak,
Established Oak, Competitive Oak, or Total Oak
SILVAH Oak: Decision Making
Summary Variables (continued)
•
Stocking of Regeneration Obstacles:
Percentage of plots that are stocked with various kinds of interfering plants and site
limitations
•
Any Interference: A plot stocked with any of the interfering vegetation types is
considered to be stocked with Any Interference.
SILVAH Oak: Key Decision Points
1. Any Competitive Regeneration > 69%
– Final removal cut for mixed hardwoods appropriate
2. Competitive Oak > 49% and Any Competitive Regeneration > 69%
– Final removal cut for mixed-oak regeneration appropriate
3. All Established Oak > 49%:
– High site quality (SI > 70): First removal cut of shelterwood appropriate
– Low to medium site quality (SI < 70): With Any Established
Regeneration > 69%, final removal cut
4. All Established Oak < 49%, but All Oak > 50%: Preparatory cut, herbicide,
and reinventory
Example Oak Regeneration Scenario 1
Regeneration Inventory found:
1.
2.
3.
4.
5.
No Competitive Oak (0% stocked plots)
Few Established Oak (5% stocked plots)
Few All Oak (15% stocked plots)
High level of Tall Woody Interference
Site Limitation: Thick Duff Layer
No site limitations
MDM = 23
Comp. oak = 0%
All Est. Oak = 5%
All oak = 15%
Oak sawlogs = 70
ft2ac-1
Thick Duff =30%
Any Int. = 70%
Deer Index = 2
Example Scenario 1: Recommended Prescription
Example Scenario 1: Recommended Prescription
Example Scenario 1: Recommended Prescription
Herbicide
Herbicide is an effective, safe and
economical technique for removing
vegetation that interferes with
establishment and growth of oak
regeneration.
Five methods of herbicide
application
1) Broadcast Spray
2) Cut and Spray
3) Stem Injection
4) Basal Application
5) Cut Stump
Example Oak Regeneration Scenario 2
Regeneration Inventory found:
1.
2.
3.
4.
Few Competitive Oak (15% stocked plots)
Moderate Established Oak (40% stocked plots)
All Oak (85% stocked plots)
High level of Tall Woody Interference
No site limitations
MDM = 23
Comp. oak = 15%
All Est. Oak = 40%
All oak = 85%
Stocking = 85%
Interference =
70%
Deer Index = 2
Example Scenario 2: Recommended Prescription
Example Scenario 2: Recommended Prescription