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A
project funded by the Joint Fire
Science Program
Thinning Experiment
Study Design
Each
combination of 4 fuel treatments will be applied to 8 replicate
treatment
plots n=32 total. Treatment plots will be 20 acres (8.1 ha,
285 X 285
m). Treatments will be applied in the summer/fall of 2002 and 2003.
Thinning Treatments (Winter 2003) |
Cut |
Cut, Limb, and Scatter |
Chemical |
Untreated Control |
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The sampling unit will consist of a 20 x 50m Modified
Whittaker plot (mod-whit plot) , centered over a 5 x 30m
Fire Management Handbook (FMH) brush belt transect. Each of
the 32 treatment plots will have three sampling units randomly
located within them, such that the edge of each sampling unit
will be >30m from the plot edge.
Thinning Treatments
Cut
- Every 4 post-settlement trees encountered in the treatment
plot will be treated, leaving every 5th post-settlement tree
- Treatment will be accomplished by cutting selected Class
1 (youngest) trees at ground level using lopping shears,
and cutting selected Class 2 and 3 trees at ground level using
a chainsaw.
- Trees will be left were they fall
Cut, Limb, and Scatter
- Every 4 post-settlement tree encountered in the treatment plot
will be thinned, leaving every 5th post-settlement tree
- Treatment will be accomplished by cutting selected Class 1 (youngest)
trees at ground level using lopping shears, and cutting selected
Class 2 and 3 trees at ground level using a chainsaw
- Class 2 and 3 cut trees will be limbed to manageable lengths
then scattered evenly across the site, except under the driplines
of uncut trees
Chemical
- A 15 foot no chemical treatment buffer will be left around old-growth
trees due to concerns for chemical soil “drift” within
the root zone of untreated trees. This will leave many untreated
post-settlement trees that are growing within the canopy
drip zone of the class 4 leave trees. We estimate that these
untreated Class 1-3 trees will constitute the 20% of the target
trees
that are prescribed to leave
- Every post-settlement piñon and juniper tree located
outside of the 15 foot buffer around old-growth trees will
be treated, including seedlings and saplings growing within
non-target shrubs.
15% Tordon 22K will be batch mixed at 3 gallon increments directly
into SP-3 backpack sprayers at a rate of 24 ounces of 15% Tordon
22K per gallon of water with 1 ounce of Blaze-on blue dye and
1 milliliter of Kinetic non-ionic surfactant
- The herbicide mixture will be applied as a streamline basal spray,
covering both the base of trees and the soil around them
- Treatment grids will include 6 sprayers spread approximately
30 to 50 feet apart (depending on tree density) along either
the north or south perimeter line. The blue dye spray line
from the previous application sweep will be followed by the inside
applicator while the outside applicator will follow a north-south
compass bearing to keep directional alignment. The remaining
4 inside applicators will intersperse between the two outside
applicators
Sampling Schedule
Pre-Treatment - (2002-2003)
5 X 30 meter brush belt transects
- Density of woody perennial plants (spring-summer)
- Cover of woody perennial plants (spring-summer)
- Density of herbaceous plants (spring-summer)
- Cover of herbaceous plants (spring-summer)
Post-Treatment - (2004-2006)
5 X 30 meter brush belt transects
- Density of woody perennial plants (spring-summer)
- Cover of woody perennial plants (spring-summer)
- Density of herbaceous plants (spring-summer)
- Cover of herbaceous plants (spring-summer)
- Seedbank density and diversity (late summer)
20 X 50 meter mod-whit plots
- Fuel measurements (summer)
Thinning and Seeding Experiment
Study Design
Each combination of the 2 thinning and 3 seeding treatments will
be applied to 6 replicate treatment plots (n=36 total). Treatment
plots will be 2.7 acres (1.1 ha, 90 X 120m). Treatments will be
applied in the summer/fall 2003 and 2004.
Thinning (Winter 2003) |
Cut-buck-scatter: 80% PJ reduction |
Control: No Thinning |
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Seeding (Spring 2004) |
Seed- Seed mixture 2lbs/acre blue grama and 3lbs/acre
bottlebursh squirreltail |
Seed-Rake |
Control: No Seeding |
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The sampling unit will consist of a 5 X 30m Fire Management
Handbook (FMH) brush belt transect. Each of the 36 treatment
plots will have three sampling units randomly located within
them, such that the edge of each sampling unit will be 20m
from the plot edge, and 10m from each other.
Thinning Treatments
Cut, Limb, and Scatter
- Every 4 post-settlement tree encountered in the treatment
plot will be thinned, leaving every 5th post-settlement
tree
- Treatment
will be accomplished by cutting selected Class 1 (youngest) trees at ground level
using lopping shears, and cutting selected Class 2 and
3 trees at ground level using a chainsaw
- Class 2 and 3 cut trees will be limbed to manageable
lengths then scattered evenly across the site, except under
the driplines of uncut trees
Seeding Treatments
Hand Seeded
- Seed mix will consist of bottlebrush squirreltail (Elymus elymoides
spp. elymoides) @ 3 pounds per acre and blue grama (Bouteloua
gracilis) @ 2 pounds per acre, the two common
perennial grasses at the study site. Seed will be biotypes
local to southern Utah and northern Arizona
- Seed will be broadcast using handheld applicator equipment
- Treatment grids similar to those described for herbicide
application will be followed to ensure even seed application
- No raking or other form of soil scarification will occur
to prevent disturbance of cultural resources in the area.
Minimizing ground disturbance may also provide less potential
habitat for weed species to invade the treatment sites
- Weed seed germination and percent live seed testing will
be conducted by the seed company and the Lake Mead NRA nursery
from batch samples provided prior to purchasing the bulk
of the seed
Sampling Schedule
Pre-Treatment - (2004)
5 X 30 meter brush belt transects
- Density of woody perennial plants (spring-summer)
- Cover of woody perennial plants (spring-summer)
- Density of herbaceous plants (spring-summer)
- Cover of herbaceous plants (spring-summer)
Seedbank Density and Diversity
(late summer)
Post-Treatment - (2005-2006)
5 X 30 meter brush belt transects
- Density of woody perennial plants (spring-summer)
- Cover of woody perennial plants (spring-summer)
- Density of herbaceous plants (spring-summer)
- Cover of herbaceous plants (spring-summer)
- Seedbank density and diversity (late summer)
Sampling Methods
FMH Brush Belt Transect
Density of woody perennial plants (trees, shrubs, and cacti) will
be measured in the 5x30m belt transect centered within each mod-whit
plot. Each
individual having >50% of its rooted base within the belt transect will
be counted. Data will be recorded by species and age class. Age class of each
individual
will be identified as either dead, immature-seedling, resprout, or mature-adult.
Cover of woody perennial plants (trees, shrubs, and cacti), and cover of bare
mineral soil, will be measured by line intercept, using the two 30m sides of
the brush belt transect as subsamples. Data will be recorded by species
and age class.
Density of herbaceous plants will be collected within five 1m2 subplots
along the two 30m sides of the brush belt transect as subsamples.
Herbaceous plants will be counted by species for each frame, separating
live and dead
individuals.
Cover of herbaceous plants will be measured by the point-intercept
method, using the two 30m sides of of the brush belt transect as
subsamples. Starting at the end of each transect, a 0.25inch diameter
sampling rod (a rigid
plumb bob), graduated in decimeters, will be lowered gently so that
the sampling rod
is plumb to the ground (on slopes this will not be perpendicular to the
ground), every 30 cm along the transect line. Since the transect
length is 30 m, there
will be 100 points from 30 to 3,000 cm. The height at which each species
touches the sampling rod will be recorded, tallest to shortest. If
the rod fails to intercept
any vegetation, the substrate will be recorded (bare soil, rock, forest
litter, etc.).
Seedbank density and diversity will be measured from a single composited
soil sample for each of the five 1m2 herbaceous plant subplots
(described above) by
pooling four sub-samples collected just outside each corner of the
subplot. All soils will be collected using a 5cm diameter x 5cm deep
(volume = 98cm3) core.
Soil seedbanks will be assayed by growing them out in a greenhousee
and counting the number of seedlings for each species. The methods
are adapted from Brenchley
and Warington (1939), later modified by Young and Evans (1975).
Mod-Whit Plot
Plant diversity will be calculated at multiple scales within the
20 x 50m mod-whit plot. The effects of disturbance on plant diversity
can vary among spatial
scales. For example, the effects on plant community diversity due
to fire and grazing can vary between 1 and
1,000m2 scales. It is possible that similar variation will occur
among management treatment in pinon-juniper woodland, warranting
the use of the spatially nested
modified-Whittaker plots in this study. Plant species richness will
be measured for all species recorded at 1, 10, 100, and 1,000m2
scales. Species evenness
will be measured among ten 1-m (0.5 x 2 m) sub-plots within each
1,000m2 plot. In addition, seedbank species richness and evenness
will be measured from seedbank
density assays at the 1m2 scale.
Fuelbed Measurements
Representative trees, shrubs, and grasses will be randomly chosen
inside each mod-whit plot to calculate biomass.
These
data will be
augmented using Taush’s allometric model to calculate piñon
fuel classes and biomass. Three fuels transects
parallel to the
long axis of
each mod-whit plot will be established to estimate downed woody
debris.
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