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Eastern hemlock removal affect small mammal abundance at Harvard Forest
Allyson L.
1
Degrassi ,
Aaron M.
2
Ellison
and Nicholas J.
1
Gotelli
1Department
of Biological Science, University of Vermont, Burlington, VT
2 Harvard Forest, Harvard University, Petersham, MA
TRAPPING SET UP: Data Collection
A • 49 Sherman live traps covering
B an area of 0.49ha (Fig. 2) were placed in
The eastern hemlock (Tsuga canadensis) is a foundation species that
each plot and set in June and July (Fig. 3).
controls ecological structure by creating stable local conditions for
other resident species; therefore, the loss of foundation species can
10m
potentially influence the structure of animal communities.
Hemlock forest are declining due to the effects of logging and invasive
sap-sucking insect Adelges tsugae (hemlock woolly adelgid: HWA).
90m
Loss of hemlocks have been known to impact ant, bird, and salamander
populations.
Loss of hemlocks may impact community composition of rodents and
shrews.
INTRODUCTION
•
•
60
50
Hemlock
Number of Captures
RESULTS
Peromyscus maniculatus
(deer mouse)
PEMA
Peromyscus leucopus
(white-footed mouse)
PELE
Napaeozapus insignis
(woodland jumping mouse)
NAIN
Tamias striatus
(eastern chipmunk)
TAST
Glaucomys volans
(southern flying squirrel)
GLVO
Logged
120
100
80
60
40
120
100
80
Hemlock
Hardwood
Girdled
Logged
60
40
20
0
Full
20
Half
Moon Phase
New
0
Full
Half
New
Moon Phase
Figure 7. Number of total species captured during full, half, and new moon phases per plot.
CONCLUSION
Clethrionomys gapperi
(red-backed vole)
CLGA
Microtus pinetorum
(woodland vole)
MIPI
Blarina brevicauda
(short-tailed shrew)
BLBR
Sorex fumeus
(smokey shrew)
SOFU
Sorex cinereus
(cinereus shrew)
SOCI
Deer mice (PEMA) and red-backed voles (CLGA) were the most abundant animals
100
93
• Rodent and shrew community variation among the different hemlock
plots (Fig. 6).
• Shifts in species abundance (Fig. 6) suggests hemlocks may drive a
competitive interaction between the Peromyscus spp. and
o
p
r
Clethrionomys.
• Peromyscus spp. and shrews may be able to utilize ecosystem
services provided by hemlocks more effectively than other species.
92
FUTURE PLANS
80
Abundance
2) Hardwood Control
60
37
40
30
22
21
20
14
2
1
1
SOFU
NAIN
MIPI
0
PEMA
Figure 1. Vegetation differences among the control and experimental plots.
Hardwood
Girdled
Treatment
Number of captures differed moon phases
Figure 4. Captured animals included mice (blue), voles (green), shrews (purple), and larger rodents (squirrels and chipmunks) (orange).
4) Logged Plot
20
0
METHODS
3) Girdled Plot
30
Figure 3. Moon phase calendar used to determine trapping
nights.
• To measure small mammal abundance and diversity in
Harvard Forest’s Long-Term Experimental Research
Hemlock (HF-HeRE) plots.
1) Hemlock Control
74 individuals
7 species
Figure 6. Species abundance per plot.
Figure 2. Sherman trap layout within all plots.
HF-HeRe
• Replicated two-block experimental design
1. hemlock control, hemlocks dominate
2. hardwood control, hardwoods dominate
3. girdled treatment, hemlocks have been girdled to simulate the
effect of HWA invasion
4. logged treatment, hemlocks have been removed to simulate the
effect of commercial logging (Fig. 1).
40
10
70m
OBJECTIVE
104 individuals
7 species
87 individuals
7 species
Number of Captures
•
120 individuals
9 species
Abundance
•
Girdled and logged plots had higher abundances
CLGA
PELE
GLVO
BLBR
TAST
Species Rank
Figure 5. Overall species rank abundance (number of individuals collected) among all plots.
SOCI
1) Mark-Recapture
2) Microhabitat Association
3) Foraging Behavior
ACKNOWLEDGEMENTS
I would like to thank: 1) NSF LTER and Harvard Forest for research and financial support, 2)
Institutional Animal Care and Use Committee (IACUC) UVM and Harvard Universities, 3) my
undergraduate field assistant and REU student Elizabeth Kennet (UVM) for all her help this
summer, and 4) Chris Degrassi for his technical assistance.