Download - Cdfr 2004 01 prsnttn saproxylicbeetlesandcumulativeecologicaleffectsofwildfireandforestharvesting
Saproxylic beetles and the cumulative ecological effects of
wildfire and forest harvesting
Saproxylic beetles and the cumulative ecological effects of
wildfire and forest harvesting
Tyler CobbPhD candidate
Dept. of Renewable ResourcesUniversity of Alberta
Tyler CobbPhD candidate
Dept. of Renewable ResourcesUniversity of Alberta
• background • hypotheses• study design• preliminary results• implications
• background • hypotheses• study design• preliminary results• implications
Talk Outline
Effects of disturbance combinations may be cumulative
1949
7 km
Swan Hills area, Alberta, CANADATwp. 63, Rge. 11, W5th
1964+ oil wells + access roads
1991oil wells
+ access roads+ logging
Source: Schneider 2002
Hypotheses
1. Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than eitherdisturbance alone. (Survey Approach)
2. Abundance of saproxylic beetle larvae is linked to changes in soil nutrients near burned trees. (Experimental Approach)
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Survey Design:1 Factor ANOVA (4 levels and 6 replicates = 24 sites)
Stand Treatments (age, density, plant composition, soil types, accessibility)
GRN BRN HAR SAL
1 Factor ANOVA (4 levels and 6 replicates = 24 sites)
Stand Treatments
GRN BRN HAR SAL
Undisturbed in > 100yrs
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Survey Design:
1 Factor ANOVA (4 levels and 6 replicates = 24 sites)
Stand Treatments
GRN BRN HAR SAL
Burned by Chisholm fire 2001
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Survey Design:
1 Factor ANOVA (4 levels and 6 replicates = 24 sites)
Stand Treatments
GRN BRN HAR SAL
Clear-cut harvested in 2001
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Survey Design:
1 Factor ANOVA (4 levels and 6 replicates = 24 sites)
Stand Treatments
GRN BRN HAR SAL
Salvaged following the Chisholm fire
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Survey Design:
Sampling Design
• summer months 2002 and 2003
• flight-intercept traps (4/site = 96 total)
• total beetles collected 15,326
• identification ~60% complete (187 species, 38 families so far!)
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
020406080
100120140
0 500 1000 1500 2000 2500Number of individuals
Estim
ated
num
ber o
f spe
cies
GRNBRNHARSAL
- diversity
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
GRNBRNHARSAL
-1.5
-1.5
-0.5 0.5 1.5
-0.5
0.5
1.5
Axis 1
Axis
2
NMS OrdinationFinal Stress = 15.08
Variance explainedAxis 1 = 0.342Axis 2 = 0.454Cumulative = 0.796
- community level
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Abs
olut
e de
part
ure
from
und
istu
rbed
catc
h ra
te (i
div.
/trap
-day
)
Glischrochilus siepmanni W.J.Brown(Nitidulidae; total catch = 64)
0.1
0.2
0.3
Pediacus fuscus Erichson(Cucujidae; total catch = 173)
0.5
1.0
1.5
Caenoscelis antennalis (Casey)(Cryptophagidae; total catch = 681)
2.0
4.0
6.0
8.0
BRN HAR SAL
negative
negative
positive
species level
H1: Combined effects of wildfire and forest harvesting on saproxylic beetles are greater than either disturbance alone.
Photo: Matti Koivula 2002Photo: Matti Koivula 2002
H2: Abundance of saproxylic beetle larvae is linked to changes in soil nutrients in near burned trees.
0.000.00
0.050.05
0.100.10
0.150.15
0.200.20
GRNGRN BRNBRN HARHAR SALSAL
Stand treatmentStand treatment
Mea
n ca
tch
rate
M
ean
catc
h ra
te
(indi
vidu
als/
trap
-day
)(in
divi
dual
s/tr
ap-d
ay)
H2: Abundance of saproxylic beetle larvae is linked to changes in soil nutrients in near burned trees.
1 Factor ANOVA (6 levels and 4 replicates = 24 enclosures)1 Factor ANOVA (6 levels and 4 replicates = 24 enclosures)
Levels: larvae abundance 0,2,5,8,10, Method CTRLLarvae allowed to feed for 2 years, soil samples collected once per yr
Experimental Design:
H2: Abundance of saproxylic beetle larvae is linked to changes in soil nutrients in near burned trees.
H2: Abundance of saproxylic beetle larvae is linked to changes in soil nutrients in near burned trees.
- Both years combined- Larval abundance corrected for mortality
0.0
2.0
4.0
6.0
8.0
0 2 4 6 8 10
pH
0.0
4.0
8.0
12.0
16.0
0 2 4 6 8 10
Tota
l C (%
)
0.00
0.20
0.40
0.60
0 2 4 6 8 10
Number of Larvae (corrected)
Tota
l N (%
)
0
40
80
120
160
0 2 4 6 8 10
Number of Larvae (corrected)
Extr
acta
ble
P (p
pm)
R2 = 0.2747p = 0.0005n = 40
R2 = 0.2504p = 0.0010n = 40
Summary• early support for both hypotheses:
H1: Combined effects of fire and harvesting
Community-level- salvage logging reduced saproxylic diversity and altered species assemblages more either fire or harvesting alone
Species-level- combined effects of fire and harvesting were greater than either disturbance alone for several species (e.g. M. scutellatus absent from SAL stands)
H2: linking beetle abundance to soil nutrients
- increased abundance of larval M. scutellatus increased total C and total N in the soil
J.K.Bedrick 2002
Implications?Implications?
Woody Debris Decomposition Soil ChemistryForest Regeneration
Woody Debris Decomposition Soil ChemistryForest Regeneration
Fire + HarvestingFire + Harvesting
Acknowledgements
Supervisors:Dr. John Spence (University of Alberta)Dr. Dave Langor (Canadian Forest Service)
Field Assistance:Iain Phillips (University of Alberta)Andrea Déchêne (University of Alberta)
Soil Chemistry:Dr. Barb Kishchuk (Canadian Forest Service)Martin Blank (Canadian Forest Service)Dr. Leonie Nadeau (Canadian Forest Service)
Taxonomic Assistance:Josh Jacobs (University of Alberta)
Funding and Logistical Support: