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Landscape-Scale Thresholds of Early
Successional Habitat Reconciling Biodiversity, Public Perception, and
Timber Yield in Managed Forests
Susan Loeb, Beverly Collins, Laura DeWald, Jeremy Hyman, Thomas Straka, Elizabeth Baldwin, Jonathan Brooks, Thomas Green
Early Successional Habitat
• Recently disturbed sites • Sparse canopy• Dominated by grasses, forbs, and shrubs • Contain unique communities
Trani et al. 2001
Trani et al. 2001
Decline of ES•Farm abandonment •Urban/Suburban Development •Suppression of natural disturbances
• Fire • Beaver activity• Flooding
Dettmers 2003
How can we best restore early successional (ES) habitat?
Questions1) Does opening size affect use, abundance, or ecological relationships of early successional species?
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Questions2) Can changing the aggregation of harvests more effectively increase abundance of early successional species at the stand and landscape levels?
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Questions2) Can changing the aggregation of harvests more effectively increase abundance of early successional species at the stand and landscape levels?
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Questions•If so, can we retain acceptable timber yield?
•Will smaller cuts be more favorably looked upon than larger cuts by the public?
Great Smoky Mountains National Park
zzzzzzzzzzzzzzzzzzzzzzzControl
(no cutting) zzzzzzzzzzzz
20-25 ac2-age harvest
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
zzzzzzzz5 1-ac harvestsAggregated
5 1-ac harvestsDispersed
2 9-ac harvestsAggregated
2 9-ac harvestsDispersed
zzzzzzzzzzzzzzzzzzzzzzzControl
(no cutting) zzzzzzzzzzzz
20-25 ac2-age harvest
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
zzzzzzzz5 1-ac harvestsAggregated
5 1-ac harvestsDispersed
2 9-ac harvestsAggregated
2 9-ac harvestsDispersed
Installed 2016
Currently beingcut
Currently beingcut
Approaches To-Date•Pre-treatment assessment of plants, birds, and bats
•Effects of patch size on bats & plants using existing ESH
•Initial studies of aggregation effects on plants, bird, bats
•Harvesting economics modeling•Public perception baseline info
Effects of Size on Biodiversity-Plants
<3 ha 3-6 ha 6-10 ha
Green, in prep
Woody plant functional traits in relation to edge• No significant difference in the relationship between seed size and distance from edge between opening sizes (p = 0.659)
• No significant difference in relationship between shade tolerance and distance from edge by opening size (p = 0.248)
Effects of Opening Size on Nocturnal Insect Abundance
Mea
n in
sect
abu
ndan
ce
Small Medium Large
Opening size
0
200
400
600
8000
200
400
600
800
2015
2014
Brooks 2016
Small = 0.2-1.6 ha Medium = 2.1-5.6 ha Large = 6.2-18.5 haP > 0.10
Effects of Opening Size on Bat Activity
Mea
n ba
t act
ivity
Small Medium Large
Opening size
0
20
40
60
80
1000
20
40
60
80
100
2015
2014
Brooks 2016
P > 0.10
Mea
n ba
t act
ivity
Interior Edge
Location
0
100
200
300
400
500
0
100
200
300
400
500
2015
2014
Positive Effects of EdgeP = 0.08
Size Effects on Birds
Common Name TotalBlack-throated Green Warbler 76Red-eyed Vireo 94Hooded Warbler 68Tufted Titmouse 68Worm-eating Warbler 60Black-and-white Warbler 55Ovenbird 34Scarlet Tanager 48Indigo Bunting 6Carolina Wren 25American Crow 12Northern Parula 16Carolina Chickadee 23Blue-headed Vireo 38Blue-gray Gnatcatcher 18Northern Cardinal 10Blue Jay 16Yellow-billed Cuckoo 6Downy Woodpecker 3Pileated Woodpecker 10Eastern Wood-Pewee 5White-breasted Nuthatch 14Wood Thrush 9Yellow-throated Warbler 36Eastern Towhee 18Red-bellied Woodpecker 13
American Redstart 0Ruby-throated Hummingbird 2Wild Turkey 0American Robin 1Rose Breasted Grosbeak 0Broad-winged Hawk 7Yellow-throated Vireo 0Turkey Vulture 1Mourning Dove 7Red-breasted Nuthatch 0American Goldfinch 1Acadian Flycatcher 0Brown Thrasher 0White-Eyed Vireo 0Cedar Waxwing 1Red-tailed Hawk 0Northern Flicker 2Hairy Woodpecker 0Ruffed Grouse 0American Robin 2Yellow-breasted Chat 14Blackburnian Warbler 1Eastern Phoebe 1Great Crested Flycatcher 1Black-throated Blue Warbler 7Swainson's Warbler 5Red Headed Woodpecker 2
Red: Edge & Successional Species
Bird Counts in 1 Acre Plots
Summer ‘16 – Initial ecosystem, plant, avian, insect, and bat responses
open edg
e
forest open
edge
Aggregation Effects – Preliminary Results
Soil M
oisture
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
OpenEdgeForest
6/06 6/13 6/21 6/27 7/04
Soil Tem
perature (C)
15
16
17
18
19
20
21
22
23
CenterEdgeForest
6/06 6/13 6/21 6/27 7/04
Soil moisture
- Higher in forest than edge and open
Soil temperature
- Highest in open, lowest in forest
i.e., openings are hot and dry compared to the forest
Soil C
O2 Flux um
ol/m2
/s
2
4
6
8
10
OpenEdgeForest
6/06 6/13 6/21 6/27 7/04
Soil respiration highest in forest, lower in edge, and lowest in open- Contrary to hypothesis that cutting would increase soil
respiration- Suggests harvesting during hot, dry weather could
partially mitigate the increased soil respiration that typically occurs when openings are created
Soil respiration values similar to values (ca. 4.5-5.1 µmol m-2 s-1) reported for a forested area at Coweeta in June
Num
ber of Visitors
0
5
10
15
20
25
30
AggregatedDisaggregated
Open Edge Forest
Species R
ichness
0
2
4
6
8
10
12
14
- Significant (P<0.001) interaction between location and aggregation;
- Insects higher in aggregated forests
- no significant difference between treatments or among locations
Diurnal Pollinating
Insects
Economic Consequences of Harvesting Configurations – Costs
Economic Consequences of Harvesting Configurations – Revenue
Economic Consequences of Harvesting Configurations – Net Present Value
Net Present Value of Each Prescription
A B C D E
-$120.00-$100.00-$80.00-$60.00-$40.00-$20.00
$0.00$20.00$40.00$60.00$80.00
$100.00$120.00
NPV
Dol
lars
1 acreAggregated
1 acreDispersed
9 acreAggregated
9 acreDispersed 20 acre
Summary & Conclusions• ESH patch size: little effect on plants & bats
• May need larger patches for ES birds
• ESH aggregation: still exploring
• Economic analysis suggests that larger, aggregated patches provide the best return
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