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Grand Canyon NP fire monitoring plot data relevant to the Tipover project Windy Bunn, Fire Ecologist, Grand Canyon NP

January 3, 2013

Grand Canyon National Park (GCNP) uses a network of forest monitoring plots to understand the effects of fire on vegetation and fuel loading. GCNP has completed three projects (Map 1) that could assist with understanding potential effects of the Kaibab National Forest Tipover project. The Northwest (NW) project was divided into three sub-units (1, 3, and 5) with sub-unit 1 burned in 1992, sub-unit 3 burned in 1993, and all three sub-units burned in 2007. The Range and Thompson projects were both burned in 2012.

Map 1: Three GCNP projects in relation to the Tipover project

Northwest Project The Northwest 1 sub-unit was burned in prescribed fire on September 28-30, 1992. This sub-unit is 275 acres with about 70% of the area classified as ponderosa pine, 16% classified as mixed conifer, and the remaining classified as spruce-fir or grassland (Map 2). Two permanent plots were measured prior to the prescribed fire, immediately after the fire, one year, two years, five years, and ten years after the fire. These two plots were burned a second time in the Northwest 1, 3, 5 prescribed fire in November 2007 and measured again after the second fire. The Northwest 3 sub-unit was burned in prescribed fire on September 20-22, 1993. This sub-unit is 1,321 acres with about 72% of the area classified as ponderosa pine, 10% classified as mixed conifer, and the remaining classified as spruce-fir or grassland (Map 2). Two permanent plots were measured prior to the prescribed fire, immediately after the fire, one year, two years, five years, and ten years after the fire. These two plots were burned a second time in the Northwest 1, 3, 5 prescribed fire in November 2007 and measured again after the second fire.

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The Northwest 5 sub-unit was burned in prescribed fire on November 8-11, 2007. This sub-unit is 1,237 acres with about 62% of the area classified as ponderosa pine, 29% classified as mixed conifer, and the remaining classified as spruce-fir or grassland (Map 2). Two permanent plots were measured prior to the prescribed fire, immediately after the fire, one year, two years, and five years after the fire. Overall the Northwest project is 2,833 acres with about 68% of the area classified as ponderosa pine, 19% classified as mixed conifer, and the remaining classified as spruce-fir or grassland (Map 2). In the Northwest project, 1,596 acres (and 4 permanent plots) have burned twice and 1,237 acres (and 2 permanent plots) have burned once since 1992.

Map 2: Three Northwest project sub-units with vegetation types and permanent plots. Red plots have burned twice and green plots have burned once since 1992.

Pre-fire data indicates that the permanent plots in the Northwest unit were dominated by ponderosa pine (Pinus ponderosa) and white fir (Abies concolor) with occasional quaking aspen (Populus tremuloides) and Douglas-fir (Pseudotsuga menziesii) present in the overstory (Table 1).

Table 1. Pre-fire composition of Northwest unit forest plots (n=6). Values are mean (±SE) percentage of dominant and co-dominant trees (>12 inches dbh).

% of basal area % of density

Ponderosa pine 89 ± 3 84 ± 5

White fir 10 ± 3 14 ± 4

Douglas-fir 0.5 ± 0.5 1 ± 1

Quaking aspen 0.5 ± 0.5 1 ± 1

Engelmann spruce 0 0

Subalpine fir 0 0

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Post-fire results are summarized in Table 2 and are addressed in detail in the following sections. In general, the prescribed fires had the largest effects on small trees, rotten logs, and litter and duff loading.

Photo 1. Photo of plot in the Northwest project five years (left) and ten years (right) after the first prescribed fire.

Photo 2. Photo of plot in the Northwest project one month (left) and five years (right) after the second prescribed fire.

Table 2. Post-fire results for measured attributes in the Northwest project. “▲” indicates an increase in value,”▼“ indicates a decrease in value, and “●” indicates no measurable change in value. The first symbol in a given cell represents the first fire and the second symbol in a given cell represents the second fire.

Attribute Category

1 – 11” dbh 12 – 17” dbh 18 – 23” dbh > 24” dbh

Tree Density ▼ ▼ ● ▼ ▼ ● ● ●

Tree Basal Area ▼ ▼ ● ▼ ▼ ● ● ●

Snag Density NA ● ● ● ● ● ●

Sound Rotten

Log Density ● ● ▼ ▼

Litter & Duff 1-, 10-, & 100-hr 1000-hr Total

Fuel Loading ▼ ▼ ● ▼ ● ● ▼ ▼

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Northwest Project—Tree Density and Basal Area Results

Tree density was measured prior to fire and in each subsequent post-fire read. All living trees larger than 6

inches dbh within the 20 m 50 m forest plot were recorded. All living trees between 1 inch and 6 inches were recorded in one half of the plot.

Tree density in the smallest size class (1 – 11” dbh) decreased from an average of 320 trees/acre to an average of 130 trees/acre five years after the first fire and decreased further to an average of 33 trees/acre by five years after the second fire. Density of trees between 12 and 17 inches dbh did not change within five years of the first fire, but there was a decrease (from an average of 42 trees/acre to an average of 32 trees/acre) in tree density in this size class by five years after the second fire. Density of trees between 18 and 23 inches dbh decreased from an average of 18 trees/acre to an average of 11 trees/acre five years after the first fire, but did not change following the second fire. Large tree (>24 inches dbh) density did not change after either the first or second fire. Tree density trends are illustrated in Figure 1.

Figure 1. Mean (±80% Confidence Interval) tree density in 20 m 50 m forest plots over time. Includes plots that have burned only once (n=2) and plots that have burned twice (n=4).

Tree basal area was calculated for the pre-fire tree data and for each subsequent post-fire read. The

diameter of each living tree larger than 6 inches (15 cm) dbh within the 20 m 50 m forest plot was used to calculate basal area of the larger size classes. The diameter of each living tree between 1 inch and 6 inches within one half of the plot was used to calculate basal area of the smallest size class.

Trends in tree basal area were similar to trends in tree density. Basal area in the smallest size class (1 – 11” dbh) decreased from an average of 46 sq.ft./acre to an average of 24 sq.ft./acre five years after the first fire and decreased further to an average of 13 sq.ft./acre by five years after the second fire. Basal area of trees between 12 and 17 inches dbh did not change within five years of the first fire, but there was a decrease (from an average of 51 sq.ft./acre to an average of 41 sq.ft./acre) in basal area in this size class by five years after the second fire. Basal area of trees between 18 and 23 inches dbh decreased from an average of 44 sq.ft./acre to an average of 28 sq.ft./acre five years after the first fire, but did not change following the second fire. Large tree (>24 inches dbh) basal area did not change after either the first or second fire. Basal area trends are illustrated in Figure 2.

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Figure 2. Mean (±80% Confidence Interval) tree basal area in 20 m 50 m forest plots over time. Includes plots that have burned only once (n=2) and plots that have burned twice (n=4).

Northwest Project—Snag Density Results

Snag density was measured prior to fire and in each subsequent post-fire read. All standing dead trees

larger than 12 inches dbh within the 20 m 50 m forest plot were used to calculate snag density.

Snag density for all size classes larger than 12 inches dbh remained relatively stable following both the first and second fires (Figure 3). The prescribed fires had no effect on snags larger than 12 inches dbh.

Figure 3. Mean (±80% Confidence Interval) snag density in 20 m 50 m forest plots over time. Includes plots that have burned only once (n=2) and plots that have burned twice (n=4).

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Northwest Project—Log Density Results

Log density was measured prior to fire and in each subsequent post-fire read. Four 50-foot transects were

installed in each 20 m 50 m forest plot to measure woody debris. All downed logs larger than 3 inches in diameter that intersected the four transects were measured and recorded as either sound or rotten wood.

Density of large, sound woody debris did not change between the pre-fire and post-fire measurements during either the first or second fire. However, large, rotten woody debris decreased from a pre-fire average of 16 logs/acre to an average of 5 logs/acre after the first fire and decreased again to an average of 0 logs/acre after the second fire (Figure 3).

Figure 4. Mean (±80% Confidence Interval) log (>3 inches diameter) density in 20 m 50 m forest plots over time. Includes plots that have burned only once (n=2) and plots that have burned twice (n=4).

Northwest Project—Fuel Loading Results

Dead fuel loading was measured prior to fire and in each subsequent post-fire read. Four 50-foot transects

were installed in each 20 m 50 m forest plot to measure dead fuel. Downed woody debris that intersected the four transects was measured and recorded by time-lag fuel moisture (TLFM) size class. In addition, litter and duff depth measurements were recorded every 5 feet along each transect. Total fuel loading decreased from an average of 35 tons/acre to an average of 17 tons/acre following the first fire and decreased further to an average of 14 tons/acre following the second fire. The decrease in total fuel loading was largely driven by a decrease in litter and duff loading. Litter and duff loading decreased from an average of 19 tons/acre to an average of 10 tons/acre following the first fire and further decreased to an average of 2 tons/acre after the second fire. Fine woody (1-, 10-, and 100-hr TLFM) fuel loading remained unchanged following the first fire and decreased from an average of 2.5 tons/acre to an average of 1 ton/acre following the second fire. Coarse woody (1000-hr TLFM) fuel loading was highly variable and, on average, remained unchanged through the two prescribed fires.

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Figure 5. Mean (±80% Confidence Interval) fuel loading in 20 m 50 m forest plots over time. Includes plots that have burned only once (n=2) and plots that have burned twice (n=4).

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Range Project The Range Prescribed Fire Project is 2,278 acres with 59% of the project classified as mixed conifer forest and the remainder a mix between spruce-fir, ponderosa pine, and early successional aspen. The Range project was ignited October 27-31, 2012. The ignition pattern on the Range project was designed to create primarily backing and flanking fire spread along the ridge tops and upper slopes within the unit. The project was the first attempt by the park to conduct prescribed fire in the mixed conifer forest type and represented the first phase in the projected multi-phase project implementation. Objectives for the project focused on reduction of large woody debris (1000-hr TLFM fuel loading) with additional objectives of remaining within the 30% threshold of high severity fire for mixed conifer forests across the landscape and reducing the number of small trees within the unit. Twenty rapid assessment protocol (RAP) plots were randomly located in the unit in 2008. These plots were re-measured in 2012 prior to project implementation to ensure that project results were as accurate as possible. Post-fire attributes were measured in the twenty RAP plots in November 2012. Due to the intentionally heterogeneous burn pattern generated during this prescribed fire, 8 of the 20 RAP plots remained unburned after the completion of this project (Map 3).

Map 3: Range project unit with burned (gray) and unburned (white) RAP plots

Pre-fire data indicates that the rapid assessment plots in the Range project were dominated by white fir and

ponderosa pine mixed with quaking aspen, Douglas-fir, Engelmann spruce (Picea engelmannii), and

occasional subalpine fir (Abies lasiocarpa) (Table 3).

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Table 3. Pre-fire composition of the Range project forest plots (n=20). Values are mean (±SE) percentage of dominant and co-dominant trees (>12 inches dbh).

% of basal area % of density

Ponderosa pine 33 ± 9 29 ± 8

White fir 32 ± 6 31 ± 5

Douglas-fir 9 ± 5 11 ± 6

Quaking aspen 12 ± 5 15 ± 6

Engelmann spruce 12 ± 7 12 ± 7

Subalpine fir 2 ± 2 3 ± 2

Post-fire results are summarized in Table 4 and are addressed in detail in the following sections. In general, the prescribed fire had the largest immediate post-fire effects on rotten logs and all categories of dead fuel loading. Longer term effects will be measured in the coming years.

Photo 3. Photo of burned plot in the Range project before (left) and one month after (right) prescribed fire.

Table 4. Post-fire results for measured attributes in the Range project. “▲” indicates an increase in value,”▼“ indicates a decrease in value, and “●” indicates no measurable change in value. The first symbol in a given cell represents only plots that burned in the fire and the second symbol in a given cell represents all plots (burned and unburned).

Attribute Category

1 – 11” dbh 12 – 17” dbh 18 – 23” dbh > 24” dbh

Tree Density ● ● ● ● ● ● ● ●

Tree Basal Area ● ● ● ● ● ● ● ●

Snag Density NA ● ● ▼▼ ● ●

Sound Rotten

Log Density ● ● ▼▼

Litter & Duff 1-, 10-, & 100-hr 1000-hr Total

Fuel Loading ▼▼ ▼▼ ▼▼ ▼▼

Range Project—Tree Density and Basal Area Results

Tree density was measured prior to fire and immediately post (within one month) fire. All living trees larger than 6 inches dbh within the 20 m diameter circular forest plot were recorded. All living trees between 1 inch and 6 inches were recorded in the 10 m diameter inner circle of the plot.

Tree density remained unchanged in all size classes in both burned and unburned plots (Figure 6) one month after the prescribed fire. Tree density will be measured again two years after the fire to capture additional fire-related changes that may occur.

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Figure 6. Mean (±80% Confidence Interval) tree density in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire.

Tree basal area was calculated for the pre-fire and immediate post (within one month) fire tree data. The diameter of each living tree larger than 6 inches dbh within the 20 m diameter circular forest plot was used to calculate basal area of the larger size classes. Diameter was not recorded for trees between 1 inch and 6 inches; therefore, these trees are not included in basal area calculations.

Tree basal area remained unchanged in all size classes in both burned and unburned plots (Figure 7) one month after the prescribed fire. Basal area will be measured again two years after the fire to capture additional fire-related changes that may occur.

Figure 7. Mean (±80% Confidence Interval) basal area in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire. Note that tree diameter was not recorded for trees smaller than 6 inches, so these trees are not included in basal area calculations.

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Range Project—Snag Density Results

Snag density was measured prior to fire and immediately post (within one month) fire. All standing dead trees larger than 12 inches dbh within the 20 m diameter circular forest plot were used to calculate snag density.

Average snag density declined slightly in each size class in the burned plots within one month of the fire (Figure 8). However, variability in snag density was too high for the results to be statistically significant in all but the middle (18 - 23” dbh) size class. The 18 - 23” dbh size class had a decline in snag density from an average of 12 snags/acre to an average of 9 snags/acre one month after fire in the burned plots and a decline from an average of 9 snags/acre to an average of 7 snags/acre in all plots within the unit (burned and unburned combined). Snag density remained unchanged in unburned plots.

Figure 8. Mean (±80% Confidence Interval) snag density in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire.

Range Project—Log Density Results

Log density was measured prior to fire and immediately post (within one month) fire. Two 50-foot transects were installed in each 20 m diameter circular forest plot to measure woody debris. All downed logs larger than 3 inches in diameter that intersected the two transects were measured and recorded as either sound or rotten wood.

Density of large, sound woody debris did not change between the pre-fire and post-fire measurements in either burned or unburned plots. Large, rotten woody debris decreased from a pre-fire average of 19 logs/acre to an average of 4 logs/acre after fire in the burned plots, but did not change in the unburned plots (Figure 9). Across the whole project unit (burned and unburned plots), large, rotten woody debris decreased from a pre-fire average of 19 logs/acre to an average of 10 logs/acre after fire.

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Figure 9. Mean (±80% Confidence Interval) log (>3 inches diameter) density in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire.

Range Project—Fuel Loading Results

Dead fuel loading was measured prior to fire and immediately post (within one month) fire. Two 50-foot transects were installed in each 20 m diameter circular forest plot to measure dead fuel. Downed woody debris that intersected the two transects was measured and recorded by TLFM size class. In addition, litter and duff depth measurements were recorded every 5 feet along each transect. Total fuel loading decreased from an average of 50 tons/acre to an average of 38 tons/acre across the project unit (burned and unburned plots combined) and decreased from an average of 48 tons/acre to an average of 28 tons/acre in only the burned plots. The decrease in total fuel loading was reflective of a decrease in all three woody fuel components in the burned plots (Figure 10). While woody fuel loading remained unchanged in unburned plots, changes in burned plots led to overall decreases in fuel loading across the project unit (burned and unburned plots combined). Litter and duff loading decreased from an average of 24 tons/acre to an average of 17 tons/acre across the project unit. Fine woody (1-, 10-, and 100-hr TLFM) fuel loading decreased from an average of 5.3 tons/acre to an average of 4.7 tons/acre across the project unit. Coarse woody (1000-hr TLFM) fuel loading decreased from an average of 21 tons/acre to an average of 17 tons/acre across the project unit.

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Figure 10. Mean (±80% Confidence Interval) fuel loading in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire. Coarse woody debris is all wood in the 1000-hr TLFM class and fine woody debris is material in the 1-, 10-, and 100-hr TLFM classes.

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Thompson Project The Thompson Prescribed Fire Project is 2,349 acres with 82% of the project classified as spruce-fir forest and the remainder a mix between mixed conifer and grassland. The Thompson Project was ignited November 2-5, 2012. The primary goal of the Thompson project was to create a buffer between the spruce-fir forests in the park and sensitive resources on the Kaibab NF. The project was designed to allow the park more flexibility in managing lightning fires in the spruce-fir forest under a more natural fire regime. The ignition pattern on the Thompson project focused on areas with large logs where fire could potentially spread log-to-log. Objectives for the project focused on reduction of large woody debris (1000-hr TLFM fuel loading) within the unit. Twenty rapid assessment protocol plots were randomly located in the unit in 2009. Post-fire attributes were measured in the twenty plots in November 2012. Due to the heterogeneous burn pattern generated during this prescribed fire, 9 of the 20 RAP plots remained unburned after the completion of this project (Map 4).

Map 4: Thompson burn unit with burned (gray) and unburned (white) RAP plots

Pre-fire data indicates that the rapid assessment plots in the Thompson project were dominated by

Engelmann spruce and quaking aspen with occasional white fir, ponderosa pine, subalpine fir, and Douglas-

fir present in the overstory (Table 5).

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Table 5. Pre-fire composition of the Thompson project forest plots (n=20). Values are mean (±SE) percentage of dominant and co-dominant trees (>12 inches dbh).

% of basal area % of density

Ponderosa pine 9 ± 4 7 ± 3

White fir 10 ± 6 10 ± 6

Douglas-fir 6 ± 3 5 ± 3

Quaking aspen 21 ± 7 23 ± 7

Engelmann spruce 47 ± 9 48 ± 9

Subalpine fir 6 ± 5 7 ± 5

Post-fire results are summarized in Table 6 and are addressed in detail in the following sections. In general, the prescribed fire had the largest immediate post-fire effects on rotten logs and all categories of dead fuel loading. Longer term effects will be measured in the coming years.

Photo 4. Photo of burned plot in the Thompson project before (left) and one month after (right) prescribed fire.

Table 6. Post-fire results for measured attributes in the Thompson project. “▲” indicates an increase in value,”▼“ indicates a decrease in value, and “●” indicates no measurable change in value. The first symbol in a given cell represents only plots that burned in the fire and the second symbol in a cell represents all plots (burned and unburned).

Attribute Category

1 – 11” dbh 12 – 17” dbh 18 – 23” dbh > 24” dbh

Tree Density ● ● ● ● ● ● ● ●

Tree Basal Area ● ● ● ● ● ● ● ●

Snag Density NA ● ● ● ● ● ●

Sound Rotten

Log Density ● ● ▼▼

Litter & Duff 1-, 10-, & 100-hr 1000-hr Total

Fuel Loading ▼▼ ▼● ▼▼ ▼▼

Thompson Project—Tree Density and Basal Area Results

Tree density was measured prior to fire and immediately post (within one month) fire. All living trees larger than 6 inches dbh within the 20 m diameter circular forest plot were recorded. All living trees between 1 inch and 6 inches were recorded in the 10 m diameter inner circle of the plot.

Tree density remained unchanged in all size classes in both burned and unburned plots (Figure 11) one month after the prescribed fire. Tree density will be measured again two years after the fire to capture additional fire-related changes that may occur.

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Figure 11. Mean (±80% Confidence Interval) tree density in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire.

Tree basal area was calculated for the pre-fire and immediate post (within one month) fire tree data. The diameter of each living tree larger than 6 inches dbh within the 20 m diameter circular forest plot was used to calculate basal area of the larger size classes. Diameter was not recorded for trees between 1 inch and 6 inches; therefore, these trees are not included in basal area calculations.

Tree basal area remained unchanged in all size classes in both burned and unburned plots (Figure 12) one month after the prescribed fire. Basal area will be measured again two years after the fire to capture additional fire-related changes that may occur.

Figure 12. Mean (±80% Confidence Interval) basal area in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire. Note that tree diameter was not recorded for trees smaller than 6 inches, so these trees are not included in basal area calculations.

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Thompson Project—Snag Density Results

Snag density was measured prior to fire and immediately post (within one month) fire. All standing dead trees larger than 12 inches dbh within the 20 m diameter circular forest plot were used to calculate snag density. Snag density remained unchanged in all size classes in both burned and unburned plots (Figure 13) one month after the prescribed fire.

Figure 13. Mean (±80% Confidence Interval) snag density in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire.

Thompson Project—Log Density Results

Log density was measured prior to fire and immediately post (within one month) fire. Two 50-foot transects were installed in each 20 m diameter circular forest plot to measure woody debris. All downed logs larger than 3 inches in diameter that intersected the two transects were measured and recorded as either sound or rotten wood.

Density of large, sound woody debris did not change between the pre-fire and post-fire measurements in either burned or unburned plots. Large, rotten woody debris decreased from a pre-fire average of 30 logs/acre to an average of 17 logs/acre after fire in the burned plots, but did not change in the unburned plots (Figure 14). Across the whole project unit (burned and unburned plots), large, rotten woody debris decreased from a pre-fire average of 25 logs/acre to an average of 17 logs/acre after fire.

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Figure 14. Mean (±80% Confidence Interval) log (>3 inches diameter) density in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire.

Thompson Project—Fuel Loading Results

Dead fuel loading was measured prior to fire and immediately post (within one month) fire. Two 50-foot transects were installed in each 20 m diameter circular forest plot to measure dead fuel. Downed woody debris that intersected the two transects was measured and recorded by TLFM size class. In addition, litter and duff depth measurements were recorded every 5 feet along each transect. Total fuel loading decreased from an average of 60 tons/acre to an average of 41 tons/acre across the project unit (burned and unburned plots combined) and decreased from an average of 75 tons/acre to an average of 40 tons/acre in only the burned plots. The decrease in total fuel loading was reflective of a decrease in all three woody fuel components in the burned plots (Figure 15). While woody fuel loading remained unchanged in unburned plots, changes in burned plots led to overall decreases in fuel loading across the project unit (burned and unburned plots combined). Litter and duff loading decreased from an average of 22 tons/acre to an average of 12 tons/acre across the project unit. Fine woody (1-, 10-, and 100-hr TLFM) fuel loading was unchanged across the project unit, but it decreased from an average of 7 tons/acre to an average of 4 tons/acre in burned plots. Coarse woody (1000-hr TLFM) fuel loading decreased from an average of 33 tons/acre to an average of 25 tons/acre across the project unit.

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Figure 15. Mean (±80% Confidence Interval) fuel loading in 20 m diameter circular forest plots before and immediately after (within one month) prescribed fire. Coarse woody debris is all wood in the 1000-hr TLFM class and fine woody debris is material in the 1-, 10-, and 100-hr TLFM classes.