ABIOTIC AND BIOTIC DISTRUBANCES

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Do natural disturbance regimes provide realistic
guidelines for managing early-successional
habitats in New England forests? 
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Major forest types in northern U.S.
Lull (1968)
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1880
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gt50 of forest vertebrates utilize early-successio
nal stands
1930
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Obligate users
1.0
RELATIVE USE
0.5
0
10
20
30
40
50
60
70
80
90
100
AGE OF STAND
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Golden-winged warbler
USGS
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FOREST MATURATION
FARM ABANDONMENT
Relative abundance of early-successional habitats
FOREST CLEARING
RETURN TO PRE-COLUMBIAN CONDITIONS ?
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How much was there?
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source Harvard Forest
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Methods to Estimate Natural Disturbance Regimes
Lorimer and White (2003)

• Sedimentary pollen and charcoal
• Presettlement land surveys
• Descriptions by early naturalists
• Reconstruction of disturbance history in
  old-growth stands
• Modern records and aerial photos
• Computer models

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Large-scale fires infrequent in New England,
800-1,200 years 1790 survey in NY found that 1
of landscape burned or open.
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Small-scale wind storms kill one to several
trees. In eastern U. S., 0.2- 2/year of all
forests are affected by wind throw. At any time,
5-50 of a forest may be affected.
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Large-scale wind storms hurricanes or tornadoes
at irregular intervals (1635, 1788, 1815, 1938,
and 1944).
1938 hurricane affected gt240,000 ha in New
England
Boose et al. (2001)
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Approximate return interval of damaging (F2)
hurricanes in New England.
Boose et al. (2001)
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Wilson 2005
Lumber Exports (Wilson 2005) vs Witness Trees
Projections (Lorimer 1977) very different
estimates of the prominence of white pine (gt10x),
indicating a large difference in the frequency
and scale of disturbance in these forests.
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Northern Hardwoods
seedling/sapling (1-15 yrs) 1-3 young pole
(15-30 yrs) 1-3 2-6
Pitch Pine- Scrub Oak
seedling/sapling 10-30 young pole
10-30 20-60
(Lorimer and White 2003)
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Early-successional forests in the eastern U.S.
Trani et al. (2001)
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What AboutBiotic Disturbances?
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Contemporary Herbivores
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flooded forest pond wet meadow
shrubs forest
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How large an area affected?
1940 1 of area
1986 13 of area
Open water areas created by beaver dams on the
Kabetogama Peninsula, northern MN.
Johnston and Naiman (1990)
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Northern Hardwoods
seedling/sapling 1-3 young pole 1-3
(Lorimer and White 2003)
beaver flowages 3.5 (Gotie and Jenks 1982)
5-11
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Even if we can accurately estimate HRNV, are
these values relevant in contemporary landscapes?
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POPULATION DENSITY
40/mi2
1100/mi2
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Road Density in the Northeast
Hoving (2001)
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100
140
120
RACCOONS
80
100
60
80
COMPOSITION ()
LANDSCAPE
RACCOON/CANID TRACKS
60
40
40
CANIDS
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AGR
20
FOR
DEV
0
0
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Patches
? 2.5 ha
? 5 ha
Winter mortality
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CONDITION-SENSITIVE PREDATION
LARGE
PATCHES
SMALL
PATCHES
FOOD QUALITY
THRESHOLD?
OCT
NOV
DEC
JAN
FEB
MAR
APR
MAY
37
12
10
3
3
8
4
6
3
5
4
5
3
6
6
UNC RATIO
2
13
13
2
12
4
11
13
5
2
8
4
8
5
9
7
5
7
4
5
0
9 JAN
6 FEB
3 APR
6 MAR
16 JAN
23 JAN
30 JAN
13 FEB
20 FEB
27 FEB
10 APR
13 MAR
20 MAR
27 MAR
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New approaches needed to provide habitat
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potential to mimic natural disturbances
modified disturbances (large and
clustered/connected)
restoration of shrublands/ modified disturbance
regime (sliding scale)
Parcelization or Fragmentation
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ME
VT
NH
NY
MA
CT
RI
MANAGING INDUCED METAPOPULATIONS may require
deviating from HRNV
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DESCRIBING HABITAT DISTURBANCES
Size
Frequency
Intensity
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Do natural disturbance regimes provide realistic
guidelines for managing early-successional
habitats in New England forests? 
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Human-generated disturbances
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Pisgah Forest in southwestern New Hampshire three
years after 1938 hurricane.