F u el a n d fi re b e ha vi or i n b a rk b eetle-affected
h i g h e l e va ti on f i ve ne e d l e p ines
Michael Jenkins and Chelsea Toone
Department of Wildland Resources, Utah State University, Logan, Utah 84322-5230
INTRODUCTION:
Recent Evaluation Monitoring and Special Technology
Development Program funded research by the Project
Leader, collaborators and students, has significantly
enhanced our understanding of bark beetle, fuel and
fire interactions (Jenkins et al. 2008), in Douglas-fir,
(Hill and Jenkins in prep.),lodgepole pine (Page and
Jenkins 2007a and b,) and Engelmann spruce
(Jorgensen and Jenkins 2011 in press, 2011 in
review). Important unanswered questions remain on
how excessive beetle-caused mortality influences
fuels and potential fire behavior in the ecologically
important high elevation five needle pines (Gibson et
al. 2008).
PROJECT OBJECTIVES:
This study will characterize and model fuels and fire
behavior in mountain pine beetle (MPB) affected
stands of high elevation five needle pines, including
whitebark, limber, foxtail, Rocky Mountain bristlecone, and Great Basin bristlecone.
Altered fuels affect fire hazard and potential fire
behavior by:
Increasing surface fuel exposure to sun and wind,
Increasing fine fuels for ignition and spread,
Increasing potential for crown fire initiation and
spread during the epidemic phase,
Shrubs and forbs may decrease probability of
ignition and dampen fire behavior.
We will measure the
forest biomass of stands
with endemic and
epidemic MPB populations and compare the
quantity and quality of
fuels present within each
beetle population phase.
ENDEMIC
En
S hrub Bi om a ss
3
2
1
0
He rbace ous Bi om a ss
1.2
DW
D Fue l Be d De pth
1
Fuel Depth (meters)
4
0.8
0.6
0.4
0.2
0
Course Woody Fuel
0.8
12
0.4
8
0
Litter
16
8
Fine Woody Fuel
12
4
8
0
Fuel Load
(tonnes per hectare)
4
0
12
Duff (di vi de d by 10)
4
4
0
Time
2
0
Time
Endemic
Epidemic
Post-Epidemic
intercrown
distance
(ICD)
crown width
(CW)
POSTEPIDEMIC
Pe
crown bulk
density
(CBD)
pine fuel zone
(Pz )
crown base height
(CBH)
non-pine fuel matrix (NPz )
W
Fuels data will be used to produce fuel
models that are customized to the actual
set of fuel conditions created by the
activity of MPB. Fuel models
will be used to predict fire
behavior in MPB
affected stands of high
elevation five needle
pines over a range of
weather variables.
EPIDEMIC
Ep
2010
Future proposed work:
The influence of fuel moisture and flammable monoterpenes on
the combustibility of conifer fuels.
Preliminary research has associated bark beetle activity with
large alterations in both foliar moisture and the quality and
quantity of host-tree monoterpenes. Values representing foliar
moisture and monoterpene levels of infested trees fall well
outside of the range for non-infested trees.
Changes in these two foliar parameters have the potential to
greatly influence surface and crown fire initiation and spread.
Given the prevalence of bark beetle infestation in western forests,
these chemical changes may have widespread and significant
effects on forest flammability.
Bark beetles alter conifer fuels by:
References:
Decreasing foliar moisture content, reducing canopy
bulk density and
Seasonal changes in foliar moisture
available canopy fuel
by needle condition
load, creating pulses of
litter and fine woody
fuels increasing surface
fuel load, and increasing shrubs and forbs.
Measured
250
Foliar moisture (percent)
Gibson, K, K Skov, S Kegley, C Jorgensen, S Smith and J Witcosky. 2008. Mountain
impacts in high elevation five needle pines: current trends and challenges. USDA FS,
FHP, R1-08-020, 32 pp.
Jenkins MJ. Fuel and fire behavior in high elevation five needle pines affected by
mountain pine beetle. (2011 in review).
Jenkins, MJ, EG Hebertson, WG Page, and CA Jorgensen. 2008. Bark beetles, fuels,
fires and implications for forest management in the Intermountain West. Forest Ecology
and Management 254(2008): 16-34.
Jorgensen,CA and MJ Jenkins. Spruce beetle induced changes to selected Engelmann
spruce fuel complexes within the Intermountain West. Forest Science (2011 in press).
Jorgensen, CA and MJ Jenkins. Predicted fire behavior in selected spruce beetle
infested Engelmann spruce stands. Forest Science (2011 in review).
Page WG and MJ Jenkins. 2007a. Mountain pine beetle induced changes to selected
lodgepole pine fuel complexes within the Intermountain Region. Forest Science 53(4):
507-518.
Page WG and MJ Jenkins. 2007b. Predicted fire behavior in selected mountain pine
beetle infested lodgepole pine stands Forest Science 53(6): 662-674.
200
* Live/new
150
* Live/old
100
Infested
50
Red/dead
0
April
May
June
July
Aug
Sept
*from Keyes, 2006 (Pinus strobus)
W
2011