do natural disturbance regimes provide realistic guidelines for managing early-successional habitats...

Do natural disturbance

regimes provide realistic guidelines for

managing early-successional

habitats in New England

forests? 

Major forest types in northern U.S.

Lull (1968)

~1880

~1930

>50% of forest vertebrates utilizeearly-successional stands

Obligate users

RELA

TIV

E

US

E

0

1.0

10 20 30 40 50 60 70 80 90 100

AGE OF STAND

0.5

Golden-wingedwarbler

USGS

FOREST CLEARING

FARMABANDONMENT

FORESTMATURATION

Rela

tive a

bu

nd

an

ce o

fearl

y-s

ucc

ess

ion

al h

ab

itats

RETURN TO PRE-COLUMBIAN CONDITIONS ?

How much was there?

source: Harvard Forest

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

Large-scale fires infrequent in New England, ~800-1,200 years 1790 survey in NY found that 1% of landscape burned or open.

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.

Large-scale wind storms: hurricanes or tornadoes at irregular intervals (1635, 1788, 1815, 1938, and 1944).

1938 hurricane affected >240,000 ha

in New England

Boose et al. (2001)

85 yr

150 yr

380 yr

>380 yr

Approximate returninterval of damaging(F2) hurricanes in New England.

Boose et al. (2001)

Wilson 2005

Lumber Exports (Wilson 2005) vs Witness Trees Projections (Lorimer 1977): very different estimates of the prominence of white pine (>10x), indicating a large difference in the frequency and scale of disturbance in these forests.

Northern Hardwoods

seedling/sapling (1-15 yrs): 1-3%young pole (15-30 yrs): 1-3%

2-6%

Pitch Pine- Scrub Oakseedling/sapling: 10-30%young pole: 10-30%

20-60%

(Lorimer and White 2003)

Trani et al. (2001)

9%

4%

Early-successional forests in the eastern U.S.

What AboutBiotic Disturbances?

Contemporary Herbivores

flooded forest pond wet meadow shrubs forest

Open water areas created by beaver dams on the Kabetogama Peninsula, northern MN.

1940: 1% of area

1986: 13% of area

Johnston and Naiman (1990)

How large an area affected?

Northern Hardwoods

seedling/sapling 1-3%young pole 1-3%

beaver flowages ~3.5% (Gotie and Jenks 1982) 5-11%

(Lorimer and White 2003)

Even if we can accurately estimate HRNV,are these values relevant

in contemporary landscapes?

40/mi2

1100/mi2

POPULATION DENSITY

Hoving (2001)

Road Density in the Northeast

0

20

40

60

80

100C

OM

PO

SIT

ION

(%

)

0

20

40

60

80

100

120

140 RA

CC

OO

N/C

AN

ID T

RA

CK

S

CANIDS

RACCOONS

LA

ND

SC

AP

E

FO

R

DE

VAG

R

2.5 ha 5 haWinter

mortality: 69% 35%

Patches

OCT NOV DEC JAN FEB MAR APR MAY

FO

OD

QU

ALI

TY LARGE

PATCHESSMALL PATCHES

THRESHOLD?

CONDITION-SENSITIVE PREDATION

9 JA

N

16 J

AN

23 J

AN

30 J

AN

6 F

EB

13 F

EB

20 F

EB

27 F

EB

6 M

AR

13 M

AR

20 M

AR

27 M

AR

3 A

PR

10 A

PR

0

2

4

6

8

10

12

UN

:C R

AT

IO

4

3 3

34 5

6

3

2

5

13

11

13

13

12

6

2

9 7 7 8 5

5

5

8

544

New approaches needed to provide habitat

Parcelization or Fragmentation

potential to mimic natural

disturbances

restoration of shrublands/modified disturbance regime

(“sliding scale”)

modified disturbances (large and

clustered/connected)

limited extreme

Fore

st A

ge

you

ng

old

MANAGING INDUCED METAPOPULATIONS:may require deviating from HRNV

ME

NHVT

NYMA

CT

RI

DESCRIBING HABITAT DISTURBANCES

Size FrequencyIntensity

Do natural disturbance regimes provide realistic guidelines for

managing early-successional habitats in New England forests? 

Human-generated disturbances

Pisgah Forest in southwestern New Hampshire three years after 1938 hurricane.