Field Data Collection Methods - Conservation Gateway...Field Data Collection Methods: All data were collected using 1/10 acre permanent plots. During this data collection effort, 30

Summary of 2012 Fire Effects Monitoring for the

Southern Blue Ridge Fire Learning Network1

Peter Bates2

December 21, 2012

Introduction: Forest Stewards, Inc. entered into a contract with The Nature Conservancy to

monitor fire effects on prescribed burn demonstration sites for the Southern Blue Ridge Fire

Learning Network (SBR FLN). We completed the following tasks as part of that contract:

1. During the summer of 2012 we collected post-burn data for 4 sites (Flat Branch, Lake James,

Needmore, and Steeltrap Knob).

2. Began initial data summarization and presented the results in a poster and the 2012 National

Convention of the Society of American Foresters Convention in Spokane, WA.

3. Presented a webinar on November 29, 2012 describing an ecozone approach to summarizing

results. That presentation serves as an outline for a proposed journal article.

Field Data Collection Methods: All data were collected using 1/10 acre permanent plots.

During this data collection effort, 30 plots were measured within the burn unit for Cold Mountain

#1, 10 plots were measured within the burn unit for Cold Mountain #2, 18 plots were measured

in the area around the Cold Mountain sites, and these will serve as control plots for both Cold

Mountain #1 and #2. An additional 20 plots were established at Woods Gap. Fifteen were

located within the proposed burn unit and 5 were located in a control area. The data collected at

each plot are described below:

Data Type Methods and Attributes

Plot location UTM coordinates of plot center collected by averaging at least 200

GPS positions

Aspect Azimuth with a compass

Landform NCVS categories: ridgetop, open slope, spur ridge, gap, knob,

plunging cove, valley bottom, bench

Elevation Determined from DEM/GIS based on UTM coordinates

Slope Nearest percent with a clinometer

Slope position Classified as either upper, mid, lower

Slope shape Classified as either flat, concave, convex

Photos 1 repeatable photo point established per plot

Fuels

Litter and duff depths

Count of 1-hr, 10-hr, 100-hr, and 1000-hr fuels (woody ≥ 3”

diameter at intersection) by diameter

Data collected and summarized using protocols developed by

Southern Research Station, Clemson office.

Trees (data collected for

all trees > 2 inches DBH

within a 1/10th

acre fixed

radius plot)

Species

DBH

Crown class: Dominant, Codominant, Intermediate, or Overtopped

Mortality class based on percent live crown

1 Final report prepared by Forest Stewards, Inc and presented to The Nature Conservancy in reference to contract

number FIRE_FSI_052212-001 2 Department of Geosciences and Natural Resources, Western Carolina University ([email protected])

Regeneration (data will be

collected for all tree

species > 1 ft tall and < 2

inches DBH within a 1/50th

acre fixed radius plot)

Stem count by species

Stem height:

1 to 2.99 ft

3 to 4.49 ft

> 4.5 ft

Stem origin:

Sprout/sucker

Single stem

Sprout clumps will be treated as a single plant with height of tallest

stem measured

Understory (data will be

collected for non-tree

species in the same 1/50th

acre plot as Advanced

Regeneration data)

% Cover in 5% increments plus 0-1, 1-2, 2-3, 3-4, 4-5% for the

following life forms:

bare ground

boulder

moss/lichen

grass/grass-like

ferns

other herbs/forbs

vines

deciduous shrubs

evergreen shrubs (includes mountain laurel and rhododendron)

mountain laurel

rhododendron

Overview of SBR FLN demonstration burn units: When combining the this year’s efforts with

those of the past, Forest Stewards, Inc, and WCU have been involved in data collection and

monitoring on a total of 13 SBR FLN burn units (Fig. 1). At least 1 controlled burn has been

completed on 10 of the 13 burn units, and the remaining 3 are prepped and scheduled to be

burned as soon as conditions allow. Other characteristics of the burn units include (Table 1):

8 of the units target Oak Hickory community types and 5 units target Yellow Pine

community types

9 units have been burned once, 1 has been burned twice, and 3 have yet to be burned

7 of the units burned to date have been spring burns and 3 of the units burned to date have

been fall burns.

Figure 1. Locations of SBR FLN burn units being monitored by Forest Stewards, Inc and Western

Carolina University as of December, 2012.

Table 1. Overview of SBR FLN demonstration burn units. Cells in green represent periods of data

collection. HERB indicates a satellite study where non-mast species < 6 inches DBH were treated with

herbicide. Cells in red represent years of prescribed burns. All burns are spring burns unless another

season is indicated.

Completed

Not

completed

Burn unit Target community(ies) 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Flat Branch Shortleaf pine-

oak

Yellow Creek Shortleaf pine-

oak Pine-oak-heath

Needmore Shortleaf pine-

oak Pine-oak-heath

Steeltrap Knob High elevation

red oak

Dry mesic oak-

hickory FALL

Tugalo Village Shortleaf pine-

oak

Silver Run Dry mesic oak-

hickory

Cold Mountain #1 High elevation

red oak

Dry mesic oak-

hickory HERB

Cold Mountain #2 High elevation

red oak

Dry mesic oak-

hickory

Davis Creek High elevation

red oak

Dry mesic oak-

hickory

Lake James Shortleaf pine-

oak

Woods Gap Dry mesic oak-

hickory

Bluff Mountain High elevation

red oak

FALL

3 top Mountain High elevation

red oak

FALL

The following figures show pre and post burn results for overstory basal by species and

advanced regeneration by species for each of the 4 burn units sampled this summer (Flat Branch,

Lake James, Needmore, and Steeltrap Knob). In all cases, postburn results represent conditions

in the 2nd

growing season after the fire.

0

10

20

30

40

50

60 B

asal

are

a (f

t^2

/acr

e)

Preburn Postburn

Overstory basal area for the Flat Branch burn unit preburn and during the second growing

season following the burn

Total preburn BA: 152.1 ft2/acre Total postburn BA: 153.2 ft2/acre

0

100

200

300

400

500

600

Den

sity

(st

ems/

acre

)

Preburn Postburn

Advanced regeneration for the Flat Branch burn unit preburn and during the second growing


Total preburn density: 1860 stems/acre Total postburn density: 990 stems/acre

0

5

10

15

20

25

30

35

40

Bas

al A

rea

(ft^

2/a

cre

)

Preburn Postburn

Overstory basal area for the Lake James burn unit preburn and during the second growing season

following the burn


0

20

40

60

80

100

120

140

160

180

200

De

nsi

ty (

ste

ms/

acre

)

Preburn Postburn

Advanced regeneration for the Lake James burn unit preburn and during the second growing season

following the burn


0

10

20

30

40

50

60 B

asal

are

a (f

t^2

/acr

e)

Preburn Postburn

Overstory basal area for the Needmore burn unit preburn and during the second growing season

following the burn


0

100

200

300

400

500

600

700

Den

sity

(st

ems/

acre

)

Preburn Postburn

Advanced regeneration for the Needmore burn unit preburn and during the second growing season

following the burn


0

5

10

15

20

25

30

35

40

45

50 B

asal

are

a (f

t^2

/acr

e)

Preburn Postburn

Overstory basal area for the Steeltrap Knob burn unit preburn and during the second growing



0

50

100

150

200

250

Den

sity

(st

ems/

acre

)

Preburn Postburn

Advanced regeneration for the Steeltrap Knob burn unit preburn and during the second

growing season following the burn


Summarizing results by ecological zone: We propose that it may be most appropriate to analyze

and present results by ecological zone rather than by individual burn units. There is considerable

variability within each burn unit, which makes interpretation of the results difficult.

Summarizing the results by ecozone will allow us to work around some of this variability, and

perhaps more importantly, would allow us to extrapolate our results to similar ecozones across

the landscape. The latter would provide resource managers with a better tool to assess how best

to use fire in landscape-scale restoration efforts.

For our analyses, we used ecozones developed by Steve Simon, which have been the

principal ecological units used by the SBR FLN. Table 2 shows the distribution of those units

within our burn units.

Our plots were primarily located in 6 of 7 ecozones that were most common in our burn units.

We had very few plots in areas classified as Acidic Coves, which is consistent with the fact that

that we did not target coves during plot location. We have pre and postburn data for 105 plots

located within the 6 ecozones, and we used those plots to evaluate fire effects by ecozone (Table

3).

Table 2. Area (acres) of each Simon Ecozone type in each burn unit

Burn Unit

Ecozone

Acidic

Cove

Dry

Mesic

Oak HERO

Montane

Oak

Hickory

Pine-

Oak

Heath

Rich

Cove

Shortleaf

Pine Oak

Total unit

area (ac)

FlatBranch 228 180

116

755 1,279

YellowCreek 148 190

102 101 183 5 728

Needmore 78 5

14 2

105 205

Steeltrap 166 151 120 385 1 12

835

Tugalo Vil 91 892

127 1 4 1,311 2,426

SilverRun 73 334

56

0

463

ColdMtn1 0

0 59 1 11

70

ColdMtn2 0

4 49 1 38

92

DavisCrk 174 55 29 471 198 118

1,045

LakeJames 516 895

23 180

339 1,954

WoodsGap 185 759

448 208 31 1 1,632

Bluff Mtn

57 16

73

3 Top Mtn 1

40 52

1

94

Total (ac) 1,660 3,462 250 1,919 693 398 2,515 10,897

Table 3. Number of plots in each ecozone

Ecozone # Plots

Dry Mesic Oak Hickory 16

HERO 7

Montane Oak Hickory 33

Pine Oak Heath 5

Rich Cove 7

Yellow Pine Oak 31

Grand Total 105

0

1

2

3

4

5

6

7

Pine Oak Heath

Dry Mesic Oak Hickory

Yellow Pine Oak

Montane Oak Hickory

Rich Cove HERO

Arb

ore

al

Mo

istu

re I

nd

ex

Ecozone characterzation: We developed an Arborial Moisture Index (AMI) based on the

species composition of the overstory trees (modeled after McNab 2003). Each tree was assigned

a moisture index value ranging from 1 (xeric) to 10 (mesic) based on conditions where that

species is typically found in the southern Appalachians. AMI is calculated for each plot based

on the average of those values for each overstory tree in the plot.

AMI varied significantly with ecozone (F=55, P < 0.001), and the values followed a logical

pattern. This to supports that the ecozones were identifying unique ecological units (Fig. 2).

Figure 2

0

20

40

60

80

100

120

140

160


Yellow Pine Oak

Rich Cove HERO Montane Oak Hickory

Pine Oak Heath

Number killed Percent remaining

0

10

20

30

40

50

60

70

80

HERO Dry Mesic Oak Hickory

Rich Cove Yellow Pine Oak

Montane Oak Hickory

Pine Oak Heath

BA

red

uct

ion

(%

)

Fire effects on overstory mortality: For many of our target communities, restoration will require

some reduction in the forest overstory. We examined total mortality of stems between 2 and 6 in

DBH to evaluate whether changes in stand structure were occurring after 1 burn, and we

summarized the results by ecozone. Ecozones varied significantly in both the number of stems

per acre killed (F=110, P < 0.001) and percent of stems remaining (F=520, P < 0.001) as

measured in the second growing season following a single burn (Fig. 3):

We also found significant differences by ecozone in the percent in basal area reduction in the

intermediate and overtopped crown classes (F=443, P < 0.001) (Fig. 4).

Fire effects on regeneration: We enter into the following discussion with the caveat that we feel

it is premature to begin rigorously assessing fire effects on regeneration. We have only collected

postburn fire results for 7 of our 13 burn units. In addition, except for 1 unit, all of our results

are for a single burn, the effects of which are often considered uninformative. However, we do

present the following observations to demonstrate some initial trends and observations.

Figure 3

Figure 4

0

500

1000

1500

2000

2500

3000

3500

4000

4500


HERO Montane Oak Hickory

Pine Oak Heath

Rich Cove Yellow Pine Oak

De

nsi

ty (

ste

ms/

acre

)

Preburn Postburn

Regeneration density: For most ecozones, there seemed to be a slight (though likely

insignificant) decrease in the density of advanced regeneration in the second growing season

following the burn. The one exception was in the Pine Oak Heath ecozone where regeneration

density did increase (Fig. 5). In is interesting that this is also the ecozone that experienced the

greatest reduction in basal area of trees in intermediate and overtopped crown classes (Fig. 4)

suggesting that opening these stands up more might have stimulated a regeneration response.

Figure 5

0

200

400

600

800

1000

1200

1400

1600

1800

Dry Mesic Oak Hickory HERO Montane Oak Hickory Pine Oak Heath Rich Cove Yellow Pine Oak

Den

sity

(st

ems/

acre

) Preburn Postburn

0

500

1000

1500

2000

2500

3000

3500


HERO Montane Oak Hickory

Pine Oak Heath Rich Cove Yellow Pine Oak

Den

sity

(st

ems/

acre

)

Regeneration by species groups: In this analysis we looked at whether different groups of

species responded differently to fire. Regenerating species were grouped into 3 categories, Oak

Hickory (all oaks and hickories), Yellow Pine (all yellow pines), and Mesophytic (all other

species). We have observed very little Yellow Pine regeneration (either pre or postburn), so we

only present the results for Oak Hickory and Mesophytic (Fig. 6). Again, while no statistical

analyses were done, there is no strong indivation that either species group responded differently

than the other in any of the ecozones. In all ecozones (with the exception of Pine Oak Heath),

there may have been a slight decrease in regeneration density, but the decrease was similar for

both species groups. Similarly, in the Pine Oak Heath ecozone, where there appeared to be an

increase in regeneration density following a single burn, both Oak Hickory and Mesophytic

species responded positively.

Figure 6

Oak Hickory

Mesphytic

0

100

200

300

400

500

600

700

800

900

1000

De

nsi

ty (

ste

ms/

ac)

Preburn Postburn

Regeneration of individual species: We pooled the results for individual species across all

ecozones to look for trends (Fig. 7). Again, we urge caution when interpreting these data;

however the results do seem to support several observations that were made in the field. First,

some species appeared to be stimulated by a single burn in some locations. These included

sassafras, blackgum, and black locust, all species that sucker from the roots. Conversely, white

pine regeneration appeared to be drastically reduced by a single burn. We should be able to

refine these results further as our monitoring continues and we gather results from additional

sites.

Figure 7

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Preburn 1GS post 1st Burn

2GS post 1st Burn

3GS post 1st Burn

1GS post 2nd .Burn

2GS post 2nd .Burn

3GS post 2nd .Burn

Pe

rce

nt

of

cro

wn

wit

h a

corn

s Unburned Burned

Fire effects on hard mast production (Cold Mt #1): At Cold Mt #1, the NC Wildlife

Resources Commission has been collecting hard mast data from about 50 oaks and hickories

located inside the burn unit and from another 50 trees outside the burn unit. Mast production

was estimated based on the percent of the crown with acorns or nuts as determined in mid to late

summer. Data collection began in 2006 prior to the initial burn and has continued each summer

through 2012. This unit has been burned twice – once during the spring of 2007 and again

during the spring of 2010.

It appeared that prescribed burning generally stimulated hard mast production. The

effects appeared greatest in the year of a burn, and then tended to taper off in subsequent years.

The pattern was similar after each of the 2 burns.

White oaks demonstrated the greatest response, with trees inside the burn unit showing

significantly greater acorn production in the summer immediately after a spring burn (Fig. 8,

Table 3).

Table 4. T-test results comparing unburned versus burned mast production for each year for white oaks

Percent crown with acorns

Unburned Burned

Year Period mean var sd mean var sd P-value

2006 Preburn 32.9 438.4 20.9 37.2 303.2 17.4 0.560896

2007 1GS post 1st Burn 16.4 175.5 13.2 45.9 764.1 27.6 0.003022

2008 2GS post 1st Burn 0.4 2.1 1.4 3.6 13.2 3.6 0.00952

2009 3GS post 1st Burn 0.4 2.1 1.4 0.7 3.1 1.8 0.695082

2010 1GS post 2nd .Burn 26.7 1100.0 33.2 56.3 1037.4 32.2 0.041853

2011 2GS post 2nd .Burn 0.0 0.0 0.0 0.0 0.0 0.0 NA

2012 3GS post 2nd .Burn 1.7 6.3 2.5 2.3 10.2 3.2 0.599126

Figure 8. White Oaks

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0


2GS post 1st Burn

3GS post 1st Burn

1GS post 2nd .Burn

2GS post 2nd .Burn

3GS post 2nd .Burn

Pe

rce

nt

of

cro

wn

wit

h a

corn

s

Unburned Burned

Similar patterns were also observed for Hickories (Fig. 9, Table 5) and Red Oaks (Fig. 10, Table

6)

Table 5. T-test results comparing unburned versus burned mast production for each year for hickories


Unburned Burned


2006 Preburn 35.0 508.3 22.5 42.5 800.0 28.3 0.583816

2007 1GS post 1st Burn 2.1 15.5 3.9 11.3 98.2 9.9 0.040778

2008 2GS post 1st Burn 27.9 265.5 16.3 35.0 535.7 23.1 0.507957

2009 3GS post 1st Burn 8.6 31.0 5.6 9.4 124.6 11.2 0.865977

2010 1GS post 2nd .Burn 16.7 576.7 24.0 28.1 721.0 26.9 0.425289

2011 2GS post 2nd .Burn 1.7 6.7 2.6 7.5 57.1 7.6 0.097458

2012 3GS post 2nd .Burn 5.0 10.0 3.2 10.0 235.7 15.4 0.451725

Figure 9. Hickories

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0


2GS post 1st Burn

3GS post 1st Burn

1GS post 2nd .Burn

2GS post 2nd .Burn

3GS post 2nd .Burn

Pe

rce

nt

of

cro

wn

wit

h a

corn

s

Unburned Burned

Table 6. T-test results comparing unburned versus burned mast production for each year for red oaks


Unburned Burned


2006 Preburn 2.7 8.1 2.8 1.6 7.2 2.7 0.09474

2007 1GS post 1st Burn 0.6 2.9 1.7 8.7 241.6 15.5 0.005638

2008 2GS post 1st Burn 48.1 617.8 24.9 33.4 552.0 23.5 0.023743

2009 3GS post 1st Burn 5.2 47.5 6.9 8.0 146.7 12.1 0.275798

2010 1GS post 2nd .Burn 10.4 421.8 20.5 25.4 629.3 25.1 0.025453

2011 2GS post 2nd .Burn 1.8 10.2 3.2 3.8 42.6 6.5 0.163946

2012 3GS post 2nd .Burn 29.1 1080.1 32.9 40.6 652.8 25.5 0.184188

Figure 10. Red Oaks

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Field Data Collection Methods - Conservation Gateway...Field Data Collection Methods: All data were collected using 1/10 acre permanent plots. During this data collection effort, 30