Bark beetle activity associated with tornado-damaged ponderosa pine in northern Arizona
Joel
1
1
McMillin ,
Richard
2
Hofstetter ,
John
1
Anhold
USFS FHP-Flagstaff, 2 School of Forestry, NAU, Flagstaff, AZ
Methods
Introduction
The US National Oceanic and Atmospheric Administration (NOAA) confirmed
that at least six tornados occurred during the early morning of October 6, 2010
in northern Arizona (Fig. 1). Analysis of satellite imagery found approximately
2,400 ha of moderately high to severe damage across >80 km of tornado paths,
plus many additional areas of low to moderate damage. There was an array of
tree damage including windthrown trees with roots still attached to soil and
trees snapped off at various heights (Fig. 2). Certain species of bark beetles,
mainly engraver beetles (Ips species), are known to infest storm-damaged trees
(Fig. 2) and potentially cause tree mortality in nearby areas. We began
monitoring bark beetle activity associated with tornado-damaged ponderosa
pine during the spring of 2011.
3a
3b
3d
3c
• Three traps baited with either I. pini, D. brevicomis or a 4 component wood borer lure were placed at each
of 13 sites
• At 10 sites bark beetle activity was evaluated in windthrown trees, broken tops, stobs & undamaged trees in
both open (high damage severity) and closed canopy (low damage severity) conditions (Fig. 3a)
• Ips pini attack densities (nuptial chambers & egg galleries) were quantified on 5 windthrown trees at each
of 2 sites by removing 200 cm2 bark samples at varying log diameters (Fig 3b,c)
• Emergence of bark beetles & associates were recorded on a weekly basis from 4 infested bolts (18 cm
diameter x 46 cm length) collected from broken tops and windthrown trees in both open and closed canopy
conditions at each of 5 sites (Fig 3d).
Preliminary Results
Objectives
• Quantify bark beetle activity associated with tornado-caused damage to
ponderosa pine forests in northern Arizona.
• Document the diversity, abundance and chronology of insects associated with
this disturbance event.
1.Numerous bark beetles (6 Ips & 5 Dendroctonus species plus species from 5 other genera), predators (4+ species), wood borers and associates were collected from
baited traps and down material in tornado impacted areas. Based on trap catches, Ips species (only I. pini shown) populations increased throughout the summer of
2011, while primary Dendroctonus species (only D. brevicomis shown) apparently did not have as large of response (Fig. 4).
2.In general, Ips activity was greater in smaller sized material (Fig. 5a) and broken tops (Fig 5b) that were shaded. Ips, D. valens (red turpentine beetle: RTB) and
wood borers were more common in open canopy stobs than closed canopy stobs; however, the opposite pattern was observed for windthrow and broken tops.
Other Dendroctonus were most common in closed canopy areas (Fig. 6).
3.An inverse relationship was detected between number of I. pini nuptial chambers and log diameter (Fig. 7) and also I. pini egg galleries and log diameter (Fig. 7).
4.Ips pini attacks (Fig. 8a) and emergence (Fig. 8b) per infested bolt were greater in closed canopy conditions compared to open canopy. Similar attack densities were
found in broken tops and windthrown trees (Fig. 8a), although there was slightly lower emergence from windthrown trees (Fig. 8b)
a
90
Closed Canopy
Ips attack rating
Open Canopy
3.00
50
2.50
40
30
20
Dendroctonus brevicomis
Ips attack rating (X +/- SE)
2.60
2.40
2.20
2.00
1.80
1.60
Beetles/trap/day
1.50
1.00
0.50
1.20
7.00
6.00
1.00
0-3 m
5.00
3-6 m
6-9 m
9-12 m 12-15 m 15-18 m
0.00
Distance from base of windthrow or broken top
4.00
3.00
Closed Canopy
Windthrown
Broken
Stob
0.00
Open Canopy
30.00
Figure 5. Ips attack density by distance from base of down
material (a) and by damage material type (b) in closed and open
canopy conditions using a 0-3 rating scale. 0 = no attacks/3 m
section, 1 = 1-5 attacks, 2 = 5- 10 attacks and 3 = >10 attacks .
2.00
1.00
2b
2.00
1.40
8.00
Wood Borer Presence
Figure 6. Presence of a
Closed Canopy
Open Canopy
(a) wood borers (all
70.00
species combined),
60.00
(b) Dendroctonus (all
50.00
species combined
except red turpentine
40.00
beetle (RTB), and (c)
30.00
red turpentine beetle
20.00
in different types of
10.00
tornado-caused tree
0.00
damage in closed and
Windthrown Broken
Stob
open canopy
conditions
b Dendroctonus (not RTB) Presence
Trees with wood borers (%)
2.80
60
0
2a
Open Canopy
b
70
10
Figure 1. A series of tornados occurred approximately 15 km west of Flagstaff, Arizona.
Additional severe tornados occurred north and south of Flagstaff.
Closed Canopy
3.00
Ips attack rating (X+/-SE)
Beetles/trap/day
80
Ips attack rating
Trees with Dendroctonus attacks (%)
Ips pini
Figure 4. Trap catches of I. pini and D. brevicomis from five tornado impacted sites
on the Flagstaff Ranger District, Coconino National Forest.
25.00
20.00
15.00
10.00
5.00
0.00
Windthrown
Acknowledgements
Our gratitude is extended to Nicholas Aflitto, Steve Dudley, Stefano Padilla, Tom DeGomez,
Monica Gaylord, Hanna Telle, and personnel on the Coconino National Forest for discussion,
data collection & entry.
5
14
4
y = 692.96x-1.848
R² = 0.743
3
2
1
14.0
12
10
y = 4543.6x-2.112
R² = 0.7139
8
6
4
2
10.0
15.0
20.0
25.0
30.0
35.0
40.0
Diameter of log diameter (cm) at sample point
45.0
10.0
8.0
6.0
4.0
2.0
0.0
0
0
12.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
Diameter of log diameter (cm) at sample point
Figure 7. Ips pini attack densities by log diameter in windthrown trees.
45.0
Broken top
Windthrown
Open Canopy
Closed Canopy
140.0
b
c
Stob
Red Turpentine Beetle Presence
Closed Canopy
120.0
Open Canopy
90.00
100.0
80.00
80.0
60.0
40.0
20.0
0.0
Broken Top
Windthrown
Open Canopy
Closed Canopy
Figure 8. Ips pini attack density (a) and emergence (b) per infested bolt collected from
broken tops & windthrown trees in both open canopy and closed canopy conditions.
Trees with RTB attacks (%)
16
Ips pini emergence from bolts
a
Ips pini emergence per bolt (X+/-SE)
6
Ips pini attacks per bolt
Ips pini attacks per bolt (X+/- SE)
2d
Ips pini egg galleries by log diameter
Ips pini attacks/200 cm2
2c
Figure 2. Tornado-caused
windthrown ponderosa pine
(a), broken tops and stobs (b).
Ips calligraphus attacks
indicated by large piles of
boring dust (c) and nuptial
chamber & egg galleries (d) in
windthrown ponderosa pine.
Ips pini attacks/200 cm2
Ips pini nuptial chambers by log diameter
Broken
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
Windthrown
Broken
Future Plans
During 2012 we will repeat trapping and monitoring activities. In particular, we will be focusing on areas adjacent to tornado swaths as we expect bark beetles to
begin attacking undamaged or partially weakened trees once downed material has been completely utilized or is no longer suitable for brood production.
Stob