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Ecological Mechanisms Linking Protected Areas to Surrounding Lands
Author(s): Andrew J. Hansen and Ruth DefriesReviewed work(s):Source: Ecological Applications, Vol. 17, No. 4 (Jun., 2007), pp. 974-988Published by: Ecological Society of AmericaStable URL: http://www.jstor.org/stable/40061891 .
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Ecological Applications.
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ECOLOGICAL MECHANISMS
LINKING PROTECTED
AREAS
TO SURROUNDING LANDS
Andrew
J. Hansen1'3
and Ruth DeFries2
EcologyDepartment,
ontana
State
University,
ozeman,
Montana
59717-3460
USA
1
Departmentf Geography
nd Earth
Systems
cience
nterdisciplinary
enter,
181
Lefrak
Hall,
University
f
Maryland,
ollege
Park,
Maryland
0742 USA
Abstract. Land
use is
expanding
nd
intensifying
n the
unprotected
ands
surrounding
many
of the world's
protected
reas. The influence f
this
and
use
change
on
ecological
processes
s
poorly
understood. he
goal
of this
paper
is to draw on
ecological
theory
o
provide synthetic
rameworkor
understanding
ow and
use
change
round
protected
reas
may
alter
cologicalprocesses
nd
biodiversity
ithin
rotected
reas and to
provide
basis
for
dentifyingcientifically
ased
management
lternatives.We
first
resent conceptual
model of
protected
reas embeddedwithin
arger
cosystems
hatoften
nclude
urrounding
human land use. Drawing on case studies n this InvitedFeature,we then explorea
comprehensive
et
of
ecological
mechanisms
y
which and use
on
surrounding
ands
may
influence
cological processes
nd
biodiversity
ithin eserves. hese mechanisms
nvolve
changes
n
ecosystem
ize,
with
mplications
orminimum
ynamic
rea,
species-area
ffect,
and
trophic
tructure;
lteredflows f materials nd disturbancesnto and out of
reserves;
effects n crucialhabitats or easonal and
migration
movementsnd
population
ource/sink
dynamics;
nd
exposure
o humans
hrough unting, oaching,
xotics
pecies,
nd disease.
These
ecological
mechanisms
rovide
basis for
ssessing
he
vulnerability
f
protected
reas
to land use.
They
lso
suggest
riteria or
designing
egionalmanagement
o sustain
rotected
areas n the ontext f
surrounding
uman
and
use. These
design
riterianclude
maximizing
the
area of functional
habitats,
dentifying
nd
maintaining cological process
zones,
maintaining ey
migration
nd source
habitats,
nd
managing
human
proximity
nd
edge
effects.
Key
words:
ecological
rocesses;
cosystem
ize;
edge effects;
abitat;
and
use
change;management;
protectedreas; vulnerability.
974 INVITED FEATURE
^°l0*C
Vd^No™
Ecological
Applications,
(4),
2007,
pp.
974-988
© 2007
by
the the
Ecological
Society
f America
Introduction
Human
societieshave
long
set
aside tracts
f
land
to
conserve
ature
n theform
f
hunting
eserves,
eligious
forests,
nd common
grounds
Chandrashekara
nd
Sankar
1998).
The current
oncept
of national
parks
evolved n the
mid 1800s as
European
colonistswere
converting
ative
landscapes
to
farms,ranches,
and
cities
Schullery
997).
A
keygoal
was the
protection
f
nature.
By
minimizing
he nfluence f
humans,
natural
ecosystems
were
expected
to continue
to
maintain
ecologicalprocesses
nd native
pecies.
During
the 20th
century, rotected
reas became a
cornerstone f the
global
conservation
trategy.
New
protected
reas
continue
to be established: he total
number
lobally
has doubled since 1975
Ervin
2003a).
The term
protected
rea refers o
any
area of and or
sea
managed
for
the
persistence
f
biodiversity
nd
othernatural
processes
n
situ,
through
onstraints
n
incompatible
and uses
(Possingham
t al.
2006).
The
basic role
of
protected
reas
is to
separate
lements
f
biodiversity
rom
rocesses
hat hreaten
heir
xistence
in
the wild
(Margules
and
Pressey
2000).
Recent
assessments
have found that
most terrestrialeserves
are
adequately protected
within heir
borders
Bruner
et al.
2001,
DeFries
et al.
2005).
Despite
the
high
evel
of
protection
fforded
ational
parks
and
other
protected
areas,
many
are
not
functioning
s
originally
nvisioned.
ritical
cological
processes uch s fire,looding,
nd
climate
egimes
ave
been altered
Lawton
et al.
2001,
Pringle
001).
Exotic
species
are
increasingly
nvading
protected
areas
(Stohlgren
1998),
and
some native
species
have
gone
extinct
n
protected
reas
(Newmark
1987, 1995,
1996,
Rivard t
al.
2000,
Brashares
t al.
2001).
For
example,
11 of
13
national
parks
in the western
United States
have lost
large
mammal
species
since
park
establish-
ment,
with 5-21.4% of
original
pecies
ost
Parks
and
Harcourt
002).
Why
are
manyprotected
reas
not
functioning
ell,
despite dequate
management
within heir
borders?
A
major
reason
may
be thathuman
anduse is
expanding
Manuscript
eceived
August
005;
revised 2 March
2006;
accepted
17
July
006;
final ersion eceived 3
September
006.
Corresponding
ditor: M.
Friedl.
For
reprints
f this nvited
Feature,
ee footnote
,
p.
972.
3
E-mail:
hansen@montana.edu
974
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June 007 LAND
USE CHANGE
AROUND PROTECTED
AREAS
975
and
intensifying
n the lands
surrounding rotected
areas,
resulting
n
changes
n
ecological
function
nd
biodiversity
ithin
rotected
reas.
Recent satellite-based
hange analyses
are
revealing
that human
populations
and intense
and use have
grown apidly
n recent ecades
around
manyprotected
areas (Hansen et al. 2004). In the tropics, road
construction,
onversion or
agriculture,
nd demand
fornatural esources re
leading
o
clearing
f
primary
forest around reserves
Mustard
et al.
2004)
and
increased
hunting
f native
species
(Escamilla
et al.
2000).
DeFries et al.
(2005)
found
that 66% of 198
reserves
n
the humid
tropics
had
undergone
oss of
forest abitat
n
the
surrounding
ands since
1980,
with
an
average
oss
rate
of 5%
per
decade
within
0 km of
the
boundary.
In other
areas,
increases in
wealth,
technology,
nd
populationdensity
re
leading
o more
rural ettlement
n
previously
ild areas. In the
United
States
ince
1950,
for
xample,
ural esidential
evelop-
mentwas the fastest rowingand use typeand now
covers25% of the ower 48 states
Brown
et al.
2005).
Some
protected
areas are
magnets
for such
rural
development
Chown
et al.
2003).
The counties round
theYellowstoneNational
Park,
for
xample,
re
among
the fastest
rowing
n
the United States
Rasker
and
Hansen
2000).
Even n
ong-established
ocieties uch as
in
China,
agricultural
nd urban and uses continue o
push
nto
unprotected
ildlands round
protected
reas
(Vina
et
al.
2007).
In recent
ecades,
cologists
ave
come
to realize hat
human
impacts
on
surrounding
ands
may
cross the
boundaries
nto
protected
reas
(Buechner
1987,
Das-
mann 1988, Schonewald-Cox1988). The creation of
buffer ones around
protected
reas was recommended
to minimize
egative
oundary
nfluences
Noss
1983).
Accordingly,
UNESCO's
Man and the
Biosphere
(MAB)
program
dvocated
managing
he ands around
protected
reas
along
a
gradient
f
decreasingly
ntense
land use
toward
protected
rea boundaries
UNESCO
1974).
More
recently,
ethodshave been
developed
o
evaluate
the effectiveness f
protected
areas,
with
consideration
f human ctivities
n
surrounding
ands
(Hockings
2000,
TNC
2000,
Ervin
20036).
For some
protected
reas that are not
functioning dequately,
systematic
conservation
planning (Margules
and
Pressey 000) has been used to guide management f
the
regions
round
protected
reas to better chieve
conservation
bjectives
e.g., Pressey
t al.
2003).
Such
efforts
o
mitigate
boundary
influences
n
protected
reas
will be most effectivef based on
scientific
nderstanding
f the
underlying cological
mechanisms.
t can be difficult
o ascertain hemeans
by
which
human
activities outside
of
protected
areas,
sometimes
ens to
hundreds f kilometers
way,
can
impact
ecological
function and
biodiversity
within
protected
reas.
Knowledge
of these
ecological
con-
nections
could
help
to answer several
management-
oriented
uestions.
How
large
s the zone of influence
around
a
protected
rea?
Are all
locations
within
his
zone of
influence
quallyimportant
o
protected
rea
functioning?
hich
ecological processes
or
species
of
organisms
within
protected
areas are
particularly
sensitive
o
surrounding
and
use? Which
and
use
types
and
intensitiesre
most
ikely
o
have
negative
mpacts
within rotectedreas?
Advances
n
spatial
ecology
have
allowed an
increas-
ing
understanding
f the
ecological
mechanisms
on-
necting
protected
reas to
surrounding
ands.
Island
biogeography
heory,
or
xample,
provides
basis for
predicting
xtinction ates
of
species
as a
function
f
habitat
fragmentation
Brooks
et
al.
1999).
This
theory
can be
applied
to address the
effects
f habitat
oss
outside of
protected
reas on
species
richness
within
protected
reas
(DeFries
et al.
2005).
Metapopulation
theoryprovides
a basis
for
determining
hether
subpopulation
f a
species
within
protected
rea is
dependent
upon population
source
areas
located in
surroundingands (Sinclair1998,Hansen and Rotella
2002).
The
purpose
f this
paper
s to
drawfrom
iverse
studies of
spatial
ecology
to derive a
comprehensive
overview f the
ecological
mechanisms
y
which
and
use outside f
protected
reas
may
nfluence
cology
nd
biodiversity
ith
rotected
reas.
This
synthesis
s
meant
to enhance the
theoretical
nderpinning
f
efforts o
assess
the effectivenessf
protected
reas
(e.g.,
Parrish
et al.
2003)
and
systematic
onservation
lanning
cross
regions
ncluding rotected
reas
Margules
nd
Pressey
2000).
Our central hesis s
that
protected
reas are
often
parts
of
larger cosystems
nd that
and use
change
n
theunprotected ortionof theecosystemmayrescale
the
cosystem,
eading
o
changes
n
the
functioning
nd
biodiversity
within
the reserve. We first
present
a
conceptual
model of
protected
reas
embeddedwithin
larger cosystems
hat
ften nclude
urrounding
uman
land use. We
then
explore
the
key
ecological
mecha-
nisms
by
which his and use on
surrounding
ands
may
influence
cological processes
and
biodiversity
ithin
reserves. These mechanisms nvolve
ecosystem
ize,
ecological process
ones,
crucial
habitats,
nd
exposure
to humans.
A
concluding
ection
suggests
how these
ecological
mechanisms
rovide
basis for
ssessing
he
effectivenessf
protected
reas and
systematic
onser-
vationplanning crossprotectedreas and surrounding
lands.
The case studies
n
the
papers
that follow
provide
more detailed
xamples
of
ways
n
which and
use can
influence
rotected
reas. The
managementmplications
of these nteractions re
developed
further
n
DeFries
et al.
(2007).
Protected Areas as Parts of Larger
Ecosystems
Protected
reas sometimes xclude a
portion
of the
area that is
needed to maintain essential
ecological
processes
nd
organisms.
his
was
recognized
y
scien-
tists
tudyingarge
mammalswith
arge
home
ranges
hat
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976
INVITED FEATURE
^'^dl^ri
Fig. 1.
Conceptual
model
llustrating
he effects f
land
use
change
on
ecosystem
unction,
a)
Protected reas as
part
of a
larger cosystem
ith
nergy,
materials,
nd/or
rganisms lowinghrough
he
cosystem,
b)
Land use
change
educes ffective
ize
of the
cosystem,
c)
Land use
change
lters
cological
flows,
d)
Land use
change
liminates
nique
habitats
nd
disrupts
ource-
sinkdynamics,e) Edgeeffects rom and use negativelynfluencehepark.
extended utsidenational
parks Wright
nd
Thompson
1935,
Craighead
1979,
Newmark
1985).
More
recently,
ecologists
have
established hat the
spatial
domains of
ecological
processes
such as natural disturbance nd
nutrient
yclingmay
extentoutside
park
boundaries
(Grumbine
1990).
Because
protected
reas were often
designated
based on factors other than
ecological
completeness,
uch as scenicvalue
(Pressey
1994,
Scott
et al.
2001),
they
ometimes o not include the areas
required
o maintain isturbance
egimes,
utrient
lows,
organismmovements,nd populationprocesseswithin
them
Fig.
la).
Following
stablishment,
rotected
reas
may
continue
o function s
parts
of
larger cosystems
because
surrounding
ands remain
undeveloped
and
continue to
provide
functionalhabitats.
f
land use
change
educes abitats
n
the
unprotectedortion
f the
ecosystem,cosystem
unction nd
biodiversity ay
be
degraded
within
he
protected
rea. The modern
oncept
of
ecosystem management grew
from the
goal
of
managing egional
andscapes
o maintain he
cological
integrity
f the
protected
reas that
they
ontain
Agee
and
Johnson
988,
Grumbine
994).
How can the
spatial
dimensions
of the effective
ecosystem ncompassing protected
rea be
quantified?
If the
goal
of the
protected
rea
is to maintain
native
species
and the
ecological processes
hat
they
require,
then he
patial
xtent
f the ffective
cosystem
ncludes
the area that
strongly
nfluences
hese
species
and
processes
Grumbine
1990).
This area can
be
mapped
based on theflows f
materials,
nergy,
nd
organisms.
Watershed oundaries re
often sed to define
he xtent
of
aquatic ecosystems
Pringle
2001).
Watersheds
encompass
he
rea of movement
f
ground
nd
surface
water. Water carriesnutrients uch as
nitrogen
nd
phosphorous,
which are critical
o
plant
and animal
growth.
Water also serves
s a conduit
for the move-
ments f
many quatic
and terrestrial
rganisms.
ence,
strong
nteractions
mong
many components
of an
ecosystem
may
occur
withinwatersheds.
Natural
dis-
turbances uch as wildfire
ove across
andscapes
from
initiation ones to run-out
zones and
differentially
influence
oils,
vegetation,
nd animal
habitatswithin
these ones
Baker
1992).
Ecosystem
oundaries
an be
delineated ased on
homogeneity
f disturbance
egimes
(Pickett
nd
Thompson
1978).
Similarly,many organ-
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June 007
LAND
USE
CHANGE AROUND
PROTECTED AREAS
977
Fig. 2.
Depiction
of the GreaterYellowstone
cosystem
s defined ased
on the
biophysical radients,
aturaldisturbance
regimes,
nd
organism
movements
modified
romHansen et
al.
[2002]
and Gude et al.
[2006]).
Shown
are land
allocation,
movement
athways
for two
migratory
pecies,
areas of
high predicted
ird
diversity
biodiversity otspots),
nd
exurban
development
ruralhomes).
The
biodiversity odeling
mask
refers o ocations oo
high
n elevation o
be within
hedomain f
the
bird
diversity redictions.
isms move
predictably
cross the
andscape,
for
xam-
ple,
to
gain
access to seasonal resources.
Ecosystem
boundaries an be defined ased on these
movements r
on the area required o maintain articular opulation
levels f these
rganisms
Newmark1985).
In
practice,defining
he actual boundaries of an
ecosystem
s
subjective.
Although
he
flowsof
water,
nutrients,
isturbance,
nd
organisms
re often nterre-
lated,
their
patial
dimensions re oftennot identical.
Water and nutrients
may
be well
represented
ithin
watershed
boundaries,
but
organismsmay migrate
among
watersheds.
ence,
t is often ifficulto define
a
particular cosystem oundary
hat
s
adequate
for ll
components
f the
ecosystem.
Also,
the
strength
f
interaction must be considered when
defining
an
ecosystem.
Ecological processes
and
organisms
n a
particular
ocation
are often
trongly
inked to
some
places,
weakly
inked o
other
places,
and not inked o
still ther laces.Forexample, limaten theCaribbean
is
heavily
nfluenced
y regional
factors
nd
is
weakly
linked o Saharan
Africavia
input
of wind-borne
oess
(Prospero
nd Lamb
2003).
Thus
ecosystem
oundaries
are
necessarily
bstractions
hat eflect
hehuman
hoice
of the
ecosystem
roperty
f focus
nd the
strength
f
interactions sed
in thedefinition.
In a
growing
numberof
examples,protected-area-
centered
cosystems
ave been defined
see
Meffe t al.
2004).
For
example,
the Greater
Serengeti
cosystem
has been defined
ased on
the
migratory
atterns
f
the
dominant
herbivore,
he wildebeest
Sinclair
1995;
see
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978
INVITED FEATURE
EcologicalApplications
Vol.
17,
No. 4
Plate 1
Serengeti
ational
ark,
anzania,
as
designed
o ncludemost f he
migratory
ange
f
he
erengeti
ildebeest
herd.
Many
ther
rotected
reas nclude
nly portion
f rea
required
y
migratory
pecies.
Wildlifen uch
rotected
reas
s
especially
ulnerableo anduse ntensificationn the
urrounding
ands. hoto redit:
. Hansen.
Plate
1).
Although erengeti
National Park is insuffi-
cientto maintain he wildebeest nd other
migratory
mammalswithin
t,
the network f wild and semi-wild
public
and
private
ands across the Greater
Serengeti
Ecosystemmay
be
nearly arge nough
o maintain hese
populations
Packer
et al.
2005;
but see Serneels nd
Lambin2001). The GreaterEvergladesEcosystem as
been defined o
encompass
he massive
ontiguous
rea
of
freshwater
lowly
flowing
seaward
in
southern
Florida.
Everglades
National
Park includes
only
a
portion
f this
arge
watershed
nd
ecologicalprocesses
within
t are
strongly
nfluenced
y
unprotected
ands
higher
n
the watershed
NAS
2003).
The Greater
Yellowstone
cosystem,ncluding
ellowstoneNation-
al
Park,
was defined
argely y gradients
n
topography,
climate,
and
soils,
and the
resulting
movement of
wildfirend
organisms
Keiter
nd
Boyce
1991,
Hansen
et al.
2002,
Noss et al.
2002).
Centered
n the Yellow-
stone Plateau
and
surrounding
mountains,
natural
disturbance egimes nd organismsmove across the
elevational
gradient
from
valley
bottoms to
high
mountains
in
response
to climate and
vegetation
productivityFig.
2).
In these
ases,
knowledge
f the
spatial
domainof
strong cological
nteractionsetween
protected
reas and the
surrounding
reas
has allowed
for
pecification
f the
larger
ffective
cosystem.
he
term
greater cosystem
s often sed to describe hese
protected-area-centeredcosystems
Keiter
and
Boyce
1991).
Recognizing
hat
protected
reas are often
parts
of
larger cosystems
elps
to
clarify
he ffects f and use.
Agriculture,
ettlement,
nd otherhuman and uses
in
the
unprotected art
of
the
ecosystemmay
alter
the
flows of
energy,
materials,
nd
organisms
cross
the
ecosystem
n
ways
that
change
ecological
functioning
within the reserve
Fig.
lb-e).
If,
for
example,
the
portion
f the
cosystem
herewildfire
ends o
gnite
s
converted
griculture,
ire
may
less
frequently
pread
into theprotectedrea and altervegetationuccession.
Similarly,
f land use decreases
the area
of suitable
habitats or wildlife
opulation
elow
ome
threshold,
the
population
size
may
fall
to the
point
where
extinction
s
likely.
Moreover,
and use
near a
protected
area
may
introduce
novel disturbances
o
which the
ecosystem
s not
adequately dapted.
Human
hunting
and intense utdoor
recreationre
examples.
Giventhat
human and use is
rapidly
xpanding
nd
intensifying
n
the
unprotected
arts
of
many protected
rea
ecosys-
tems,
t is critical hatwe better nderstand
ts
effects.
Knowledge
of
the mechanisms
onnecting
and use
to
protected
areas
can
provide
an
objective
basis for
defininghespatialdomainof the effectivecosystem
encompassing
protected
reas
and for
managing
the
unprotected
ands to
maintain
cological
function
nd
biodiversity
ithin
rotected
reas.
Mechanisms
inkingLand Use
to Protected
Areas
Advances n
ecological
heory
ave
allowed
ncreased
understanding
f
how the
spatial
patterning
cross
landscapes
and
regions
influences
ocal
ecosystems
(Turner
t al.
2001).
Island
biogeography,
pecies-area
relationships,metapopulation
dynamics,
disturbance
ecology,
nd
landscape
ecology
have
increasingly
een
applied
to
questions
f conservation
iology,
ncluding
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AREAS
979
Table 1 General
mechanisms
y
which
and use
surrounding rotected
reas alters
cological
processes
within
eserves.
General
mechanism
and
type
Description
Examples
Change
neffectiveize of
reserve
Minimum
ynamic
rea
Temporal
tability
f serai
stages
s a function f the
Hurricanes
n
Puerto
Rico
area of the reserve elative o the ize of natural (Shugart1984).
disturbance.
Species-area
ffect
As wild habitats
n
surrounding
ands
are
destroyed,
he
Fragmented
orestsn
Kenya
functionalize of the reserve s decreased nd risk f
(Brooks
et al.
1999);
harvest
extinction
n the reserve s increased. of
primary
orest utside
Calakmul
Biosphere
Reserve,
Mexico
Vester
t al.
2007).
Trophic
tructure
Characteristic
patial
scales of
organisms
iffer ith Loss of
predators
n Barro
trophic
evel uch that
organisms
n
higher
evels re Colorado Island
Terborgh
lost
as
ecosystems
hrink. et al.
2001).
Change
n
ecological
flows
into and out of reserve
Initiation nd
run-out
Key ecologicalprocesses
move across
andscapes.
Fire
n
Yellowstone
National
zones
Initiation nd run-out ones for
disturbance
may
ie
Park
Hansen
and Rotella
outside
reserves.
2001).
Location
n
watershed
r
Land use
in
upper
watersheds r airsheds
may
alterflows Rainfall nMonte Verde loud
airshed intoreservesower nthe watershed r airshed. forestLawtonet al. 2001).
Loss of
crucial
habitat
outside
f reserve
Seasonal
and
migration
Lands outside f
reserves
may
contain
unique
habitats
Large
mammals
n
the Greater
habitats
that re
required y organisms
within eserves.
Serengeti
Serneels
nd
Organisms
equire
orridors
o
disperse mong
Lambin
2001);
antelope
n
reserves r to
migrate
rom eserves o
ephemeral
GreaterYellowstone
Berger
habitats.
2004).
Population
ource-sink
habitats
Increased
xposure
o
Unique
habitats
utside f reserves
re
population
ource Birds round Yellowstone
humans
t
park
edge
areas
required
o
maintain ink
populations
n National Park
Hansen
and
reserves.
Rotella
2002).
Hunting/poaching;
Negative
human
nfluences rom he reserve
eriphery
Eurasian
badgers
n
Donana
exotics/disease
extend ome
distance
nto
protected
reas.
Park
Revilla
et al.
2001);
spread
of disease from
etsto lions n
Serengeti
ational
Park
Packer
et al.
1999).
the
design
of nature
eserves
Pressey
t al.
1993,
Noss
and
Cooperrider
994,
Prendergast
t al.
1999).
These
bodies
of
theory
an
also be
applied
to
understanding
how
changes
in the
unprotected
parts
of
greater
ecosystems
may
influence
rotected
reas.
Here we
synthesize
cross
these bodies
of
theory
o
develop
a
simple
conceptual
framework
or
understanding
ow
changes
urroundingrotected
reas alter
he
cological
processes
within
hem.
According
o our
framework,
four
general
mechanismsinkhuman land uses with
ecological
function
ithin
rotected
reas.
These
mech-
anisms
nvolve
ffective
ize of
the
ecosystem,
lows
f
ecological
process
ones,
crucial
habitats,
nd
exposure
to humans
t
reserve
dges
Table
1).
We
will
describe,
for ach
of
mechanisms,
hevarious
forms
n which
hey
may
be
expressed,
he
conceptual
basis,
and
illustrative
examples.
Effective
ize
of ecosystem
We refer
o effective
ize of
the
ecosystem
s the
area
that
ncludes
cological processes
nd
organisms
integral
o the
protected
rea. This often s correlated
with he rea
of wild and semi-wild abitats
within
nd
surrounding
the
protected
area.
By reducing
this
effective
ize,
land use can
negatively
nfluence oth
ecological processes
and
communitydiversity
nd
structure
Fig.
lb).
Minimum
ynamic
rea.
Island
biogeography
heory
suggests
hatthe number f
species
n a nature eserve
results from
the balance between colonization
and
extinction.f protected reas are increasinglysolated
from xternal
olonization
ources,
extinction ill hen
become the dominant
population
process affecting
equilibrium
n reserves
nd
species
numbers
will
decline
to a
new
level,
according
to Pickett nd
Thompson
(1978:28).
Hence it
s
critical
o maintain ecolonization
sourceswithin
rotected
reas. Natural
disturbances a
key
force
n
driving atch
dynamics
within nd
among
protected
reas
and resources vailable
to
organisms.
Landslides, floods,
wildfires,
nd hurricanes nitiate
succession nd maintain
esources
or
pecies
ssociated
with ach serai
stage.
Bormann
nd Likens
1979)
used
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INVITED FEATURE
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17,
No.
4
the term
shifting teady-state quilibrium
o define
landscapes
where isturbance
as
adequate
to maintain
each serai
stage
n
relatively
onstant
proportion
ver
time. The location of disturbance hifts cross the
landscape
over
time,
but the
representation
f
early-
and late-seral
patches
across
the
landscape
remains
within steadystate. Such landscapes can support
relatively igh
numbers f
organisms
ecause
recoloni-
zation sources re
continuously
maintained or
pecies
requiring
ither
arly-
r late-seral onditions.
Pickett nd
Thompson
1978:27)
defined minimum
dynamic
area as the smallest area with a natural
disturbance
egime,
which
maintains
nternal ecoloni-
zation
sources,
and hence minimizes xtinction.
n
other
words,
minimum
ynamic
rea is the mallest rea
withinwhich he
natural isturbance
egime
maintains
shiftingteady-statequilibrium.
As land use
change
reducesthe
effectiveize of
the
ecosystem
ontaining protected
rea,
the
ecosystem
s
increasinglyikely o fall below the minimum ynamic
area
(Baker 1989).
n this
ase,
the
protected
rea itself
will be too
small to maintain
dynamic teady-state
equilibrium
nderthe nfluence f
naturaldisturbance.
At this
point,
ecolonization ourcesfor
pecies
re lost
and
extinctionates
will
rise.How
big
does
an
ecosystem
need be to maintain
dynamic teady-statequilibrium?
Shugart
(1984)
and Baker
(1992)
suggested
that a
landscape
needs to be at
least 50 times
arger
han the
area of the
largest
disturbance to maintain this
equilibrium.
We
are not aware of
any
studies that
have docu-
mented
change
n
effective
cosystem
ize
resulting
n
loss ofminimumynamicrea and loss ofspecieswithin
a
protected
rea. Baker
1989)
found hat he
Boundary
Waters Canoe Area in
northernMinnesota was not
large enough
to maintain a fire-induced
teady-state
equilibrium.
Wimberly
t al.
(2000)
found that the
minimum
ynamic
rea induced
by
fire
n
the
Oregon
Coast
Range
in
pre-European
settlement imes was
larger
than the
old-growth
orest eservesmaintained
today. McCarthy
nd
Lindenmayer
1999, 2000)
used
spatially
xplicit opulation iability
models o estimate
the
minimumize of
protected
reas needed o maintain
viable
populations
of forest
marsupials
n Australia
undervariousdisturbance
egimes.
Species-area effects. A well-known enetof island
biogography heory
s that the number f
species
that
are found n an oceanic
sland or
in a
habitat
ragment
is a function f
its area.
A
large
body
of
empirical
evidence
ndicates hat the number f
species
termed
species
richness),
,
increaseswith rea
A,
according
o
the
quation
S
=
cAz where and
z
are constants
e.g.,
Rosenzweig
995).
Hence,
pecies
ichnessncreaseswith
island or
habitat
rea,
at a
decelerating
ate for
arger
areas.
The
primary xplanation
s that
given pecies
s
less
ikely
o
go
extinct
f
the area of suitablehabitat s
large
enough
to
provide
the resources
o
allow
for a
population
ize
larger
han a minimum iable
popula-
tion below
which risk of
extinctions
elevated
Pimm
et al.
1988).
The
species-area
elationship
as been used
to
predict
the
consequences
of
reducing
the size of
a habitat
through
onversion o
intensiveand
uses
for
review,
see Cowlishaw
1999).
A
contraction
n habitat
from ts
original rea to its new area is predicted o lead to a
decline from
he
original
number f
species
to a new
total based
on the size of the
fragment.
his
number s
expected
to be further
educed
through
ime as
the
effects f
isolation ead to
local extinctions
ithin he
fragment,
ue
to small
population
izes.
n
a test
f this
approach,
Brooks
et al.
(1999) surveyed
irds
n
upland
forest
fragments
n
Kenya. They compared
current
species
richness
orforest irdswith hat
from he
time
prior
o habitat
fragmentation,sing
museum
records.
They
found hat ach of
the fivehabitat
fragments
ad
undergone
extinctions f
forest birds and
that the
number f extinctions as
close to that
predicted,
ased
on thechange n area.
Following
habitat
ragmentation,
herelaxation
o the
new reduced
species
richness
may
take decades
to
centuries r more
Burkey
1995,
Brooks
et al.
1999).
The term extinction ebt s used
to denote henumber
of
species
that are
expected
o become extinct
s the
communitydjusts
o a
new,
maller,
rea of habitat.
n
the New World
tropics,
deforestation s
sufficiently
recent
that few extinctions
have
yet
occurred.
In
confirmation f
the
species-area approach,
however,
Brooks
and Balmford
1996)
and
Brooks et
al.
(1997)
found that the
predicted
number of
extinctions
or
Atlantic orests f South
America nd insular outheast
Asia closelymatched he numbers f speciescurrently
listed s threatened
ith xtinction.
n
tropical
orests f
Africa,
Cowlishaw
1999)
predicted
hatcurrent
efor-
estationwill
eventually
esult
n
the xtinction
f >30%
of
the forest
rimate
auna
n each of several ountries.
The
implication
f the
species-area
relationship
or
protected
reas is that the
number of
species
in a
protected
rea
will
decline as
the effectiveize of the
reserve s reduced
through
estruction
f the
unpro-
tectedhabitats
urrounding
he reserve.
his
point
was
illustrated
y
Pimm nd Raven
2000). They
focused n
biodiversity
otspots
around the world
identified
y
Myers
t al.
(2000).
These
hotspots
ave
already
uffered
disproportionateoss
of
primary egetation,meaning
thatthe
many pecies hey
ontain re
under
particular
threat f extinction.
sing
the
pecies-area
elationship,
Pimm and Raven
(2000) predicted
hat
more
species
would be lost
f
onlyhotspots
ow
n a
protected
tatus
were aved than
f
all
hotspot
habitats
both
nside nd
outside
protected
reas)
were aved.
The
species-area pproach
was
applied
to three f the
case
study
ocations
reviewed
n
this
nvited Feature:
Maasai East
Africa,
Southern
Yucatan,
and
Greater
Yellowstone
H.
L.
Rustigian
t
al.,
unpublished
anu-
script).
Habitats
hathad been
deforested
nd converted
to
agriculture,
ettlements,
r rural
dispersed
homes
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USE CHANGE
AROUND
PROTECTED
AREAS
981
Table 2. Loss of habitat
ince
pre-European
ettlementimes
nd
predicted
xtinctionsf birds
nd
mammals
under
urrent
remaining
abitat nd habitat
emaining
f
all
unprotected
ands are
converted o
human and
uses.
No.
(and %)
species
predicted
xtinct
Total
Original
Original
Underfull
Location
area
(km2)
habitat ntact
richness
Current
conversion
Maasailand,East Africa 193405 55% 756 107(14.2%) 262(34.7%)
Greater
Yellowstone,
USA
95
363
89%
284
14(4.9%)
26(9.2%)
Mayan
Forest,
outhern ucatan Peninsula
120 109
70%
315
26
(8.3%)
75
(23.8%)
Notes:
Data are fromH. L.
Rustigian
t
al.
{unpublished
anuscript).
ichness s the
number f
species.
since
pre-European
ettlementimeswere
onsidered ot
suitablefornativebird and mammal
pecies.
Based on
loss of habitats rom
re-European
ettlement
imes,
he
ecosystem
roundeach
park, hey redicted
loss of
5-
14%
of
species among
the sites
(Table
2).
If
all
unprotected
abitats were converted o human land
uses,
9-35%
of
species
were
predicted
o be lost.
A
limitation f the
species-area pproach
to estimat-
ing fragmentationffectss thatspeciesdiffern their
tolerance
o the
type
nd
intensity
f human
and
use.
Many
native
species
find suitable habitat in human-
altered
andscapes
and some of these
species
become
more abundant
under certain and uses
(McKinney
2002).
The
approach
willbe most ffectivef t s
applied
to
species
hat
re unable to tolerate hehuman-induced
changes
to the
unprotected
ortion
of the
ecosystem.
The
approach
will lso be more ccurate
f
he
uality
f
losthabitats
s considered. ester t al.
(2007)
found hat
tall
primary
forest
has been
disproportionately
e-
stroyed
n the southern ucatan
region.
everal
pecies
of
trees nd
butterfliesre
uniquely
ssociated
with his
foresttype and may have been disproportionately
affected
y
ts
oss in area.
Trophic
tructure.
A
third
onsequence
of
reducing
the effective
ize of nature reserves s an altered
representation
f
organisms
t various
levels of the
foodchain.
Perhaps
the most
typical
ase is the oss of
high-levelpredators
and the release of meso-level
predators
r herbivores. ome
range
size and
density
are
associated
with level
in
the food chain.
Top
predators
tend to have
relatively arge
home
range
requirements
nd low densities.
onsequently, hey
re
particularly
ensitive o extinction s effective eserve
size
decreases
Schonewald-Cox
1988,
Woodroffe nd
Ginsberg 998).
Perhaps
the
most direct
evidence that
trophic
structure
n
protected
reas varies
with
ffective
ize of
ecosystem
omes from orrelational
tudies of
species
extinction
n
protected
reas of
differing
ize. Rivard
etal.
(2000)
found
hat xtinction
atesof mammals
n
Canadian
national
arks
were ssociatedboth
with
ark
area and
with he
extent f intense anduse outsideof
parks.
Moreover,
they
found
that
species
with
large
home
ranges,
ypical
f
species
t
higher rophic
evels,
were more
likely
to suffer xtinction.Evidence for
similar
patterns
n
aquatic systems
omes
from Post
et al.
(2000),
who
studied
rophic
tructure
n 25 north-
temperate
akes.
They
found that
the
length
f
food
chains was
positively
elated o
ecosystem
ize
(size
of
the
lake).
Specifically,
igher
rophic
evels
were more
commonly
ound n
larger
akes.
In
some
systems,
hese
top predators
nfluence he
abundance of
organisms
ower
n
the food
chain with
cascading
ffects
hroughout
he
ecosystem.
ence,
oss
of
the
top predators
may
allow
meso
predators
or
herbivores o become ncreasinglybundant.Thiseffect
on
trophic
tructure as
documentedn
a
study
f sland
habitat
fragments
reated
by
a water
impoundment
project
n
Venezuela
Terborgh
t al.
2001).
Vertebrate
predators
went
extincton small-
and
medium-sized
islandsbut remained n
larger
slands.
Densities
f seed
predators
nd herbivores
ere
10-100 times
higher
han
thoseon the
mainland,
robably
ue to the
release rom
predation.
These
changes
cascaded
through
he food
chain,
resulting
n
severe
reductions
n
densitiesof
canopy
tree
eedlings
nd
saplings.
Trophic
cascades
associated with
top predators
re
also
suggested
n
the
GreaterYellowstone
Ecosystem.
The recent eintroductionfthewolfCanus upis), top
predator
hathad
been extinct or60
years,
ppears
to
be
expanding
the
scavenger
community,
reducing
mesocarnivoresnd
ungulate opulation
izes,
releasing
the
riparian lant community
hatwas
overbrowsed
y
ungulates,
and
allowing
for
expansion
of
riparian-
dependent
ird ommunities
Ripple
and Beschta
004).
Thus,
reduction n
the effectiveize of a
protected
area is
predicted
o result n losses in
species
due
to
change
n
landscapedynamics,
pecies-area
ffects,
nd
loss of
top
carnivores. s the
unprotected
ands
around
nature reserves re
increasingly
onverted o
intense
human and
uses,
ffective
cosystem
ize s reduced.
or
relativelyewprotectedreas do we know theeffective
size of the
cosystem
nd the
rateof oss to human
and
use.
Rustigan
t al.
{unpublished
ata)
found
that,
for
three ase
study andscapes,
he oss rate ince
presettle-
ment
times was substantial:
11%, 30%,
and 45% for
Greater
Yellowstone,
Mayan
Forest,
and Greater
Serengeti cosystems
have
been converted o
intense
humanuses.
Ecologicalprocess
ones
Just s
organisms
move cross
andscapes
t character-
istic
cales,
cologicalprocesses
esult n
flows f
energy
and materials
long predictable athways.
hese flows
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INVITED FEATURE
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may
be
important
o
ecological
functionn
influencing
local
ecological rocesses
uch
s
primary roductivity
r
habitat
uitability.
o the xtent hat and use conversion
and intensificationlters
ecological
flows across the
landscape,
t
may
mpact
he
ecologicalfunctioning
nd
biodiversity
ithin
rotected
reas
Fig.
lc).
Disturbance nitiation nd run-out ones. Disturb-
ances tend o be initiated
n
particular
andscape ettings
and move to other ocations
n
the
landscape.
Inter-
actions between the location
where disturbance
gets
started
initiation ones)
and locations wheredisturb-
ances
move
to
run-out ones)
nfluencehenature f the
disturbance
egime
n an area
(Baker
1992).
In south-
western
Montana,
for
example, ightning
trikes ccur
across
the
andscape,
but more
frequentlygnite
ires n
dry
valley-bottom rasslands
than in moist conifer
forests
n
the
uplands
Arno
and Gruell
1983).
These
fires
hen
preadupslope
o the onifer orests.
hus,
the
juxtaposing
of
grasslands
nd conifer orests
trongly
influences he regionalfireregime.Local disturbance
regimes
an best be maintained n
protected
reas that
include the
disturbance
nitiation ones within their
boundaries
Baker
1992).
In the case of the Montana
example,
a
protected
rea
placed only
in the
upland
conifers
may
uffer oreor less
frequent
ire,
epending
on
the
management
f the
valley-bottom rasslands
outsideof the
protected
rea.
It is also
important
o include disturbance un-out
zones within
heboundaries f
protected
reas.
Run-out
zones
may
ontain
nique
biotic onditions
nd habitat
patterns mportant
o
ecological processes
nd
organ-
isms.
For
example,
flood
severity
ften ncreases
rom
headwaters o large floodplains. he largescoursand
bare
gravel
ars and themosaic of serai
tages
hatform
on
floodplains upporthigh
evels
of
biodiversity
Saab
1999).
A
protected
rea that does not contain this
disturbance un-out one
will
not include hese
unique
riparian
egetation
ommunities.
n
protected
reas that
omit either the initiationor run-out
zones,
human
manipulation
f
disturbance
may
be
required
o main-
tain
landscape patterns
nd
organisms
Baker
1992,
Arcese nd
Sinclair
1997).
Location in watershed r airshed. Protected reas
may
be
heavily
nfluenced
y
hydrologic
lows
and
weather
ystems.
or
example, rotected
reas
through-
out the world are threatenedycumulative lterations
in
hydrologic onnectivity
ithin he
larger
andscape
(Pringle
2001).
Humans are
altering
hydrologic
lows
directly y
dams,
water
diversions,
roundwater
xtrac-
tion,
and
irrigation,
nd
indirectly y altering
and
cover,
which
may change
ratesof
transpiration,
unoff,
and soil
storage.
These flows f water
ransport nergy,
nutrients,ediments,
nd
organisms.
The location of a
given protected
rea
within
a
watershed,
elative o
regional quifers
nd wind and
precipitationatterns,
an
play
a
key
role
n ts
response
to
human disturbance ransmitted
hrough
he
hydro-
logic cycle.
Protected
reas located
n
middle
nd lower
watersheds ften
experience
ltered
flow
regimes
nd
inputs
f exotic
rganisms
nd
pollution
rom
pstream.
The Colorado
River
withinGrand
Canyon
National
Park,
for
example,
has
undergone
dramatic
trans-
formation ue
to dams
and intense
and use
in the
headwaters
f thewatershed
Cohn
2001).
Alteredwater
temperaturesnd loss of flooddeposition f sediments
have
changed
habitats,
eading
to a substantial
educ-
tion of nativefishes.
Waterborne
eeds of
exotic
plants
such s saltcedar
Tamarix
pp.)
have ed to
entirely
ew
riparian
ommunities
nd loss
of native
iparian
pecies
such as the
Willow
Flycatcher
Empidonax
raillii).
Protected
reas
in
upper
watersheds,
n
contrast,
re
vulnerable o
land use lower
n the watershed.
hese
human ctivities
may provide
vectors
or xotic
pecies
and disease to
penetrate
he
upper
watershed.
heymay
also result
n
genetic
solationof
populations
n head-
waters.
n the northern
ocky
Mountains,USA,
native
west-slope
utthroat
rout
Oncorhynchus
larki
ewisi)
historicallyccupiedentirewatersheds.ubpopulations
in headwaters
may
have been
dependent
on source
populations
n lowlands.
Mainstream
opulations
were
forced
o
extinction
y
the
ntroductionf exotic
trout
species
nd
possibly
y
habitat
hanges
ssociated
with
irrigation
nd
other ntense and
uses.
Consequently,
populations
urviving
n
headwater
treams
n
national
parks
are
subject
to a
high probability
f
extinction,
probably
because
they
no
longer
receive
mmigrants
from ource
populations
n lowland streams
Shepard
et
al.
1997).
This discussion
of watershed
ffects lso
applies
to
airsheds.
Change
n
regional
anduse
may
alter limate
and nutrient epositionwithin downwindprotected
areas considerable
distances
away
(Lawton
et
al.
2001).
Tropical
montane cloud
forests
n
Central
America
depend upon prolonged
mmersion
n clouds.
Clearing
f forests
n Costa
Rica's Caribbean
owlands
appears
to have reduced
cloud cover
and increased
cloud
height
n
cloud
forests,
uch
as
in Monte
Verde
National
Park,
ltering cosystem
unctionnd
possibly
contributing
o
thedecline f 20-50
species
f
frogs
nd
toads
in Monte Verde
National Park
Nair
et al.
2003).
Such
changes
n
ecosystem rocesses
are
especially
difficult or
managers
of
protected
reas
to
perceive
because
they may
resultfrom
changes
in the
air or
watershed t longdistances rom heprotectedrea.
Crucial
habitats
Protected
reas
may
not
contain
the full suite
of
habitats
equired
y organisms
o meet
heir nnual
ife
history requirements.
easonally important
habitats
may
ie outside
heboundaries
f
protected
reas.
Land
use in the
unprotected
ortion
f
ecosystems
may
alter
or
destroy
hese easonal
habitats,
s
well as
movement
corridors
onnecting
hese habitats
to
protected
reas
(Fig.
Id).
This situation s common
because
of the nonrandom
location of
protected
areas
relative to
biophysical
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June 007
LAND USE CHANGE
AROUND PROTECTED
AREAS
983
conditions
and habitats. Protected areas
are often
located
in
relatively
harsh
biophysical
settings
nd
represent
he colder or
hotter, rier,
more
topograph-
icallycomplex,
nd/or
ess
productive ortions
f the
broader
cosystems
n
which
hey
ie
Scott
et al.
2001).
Intense uman and
use,
n
contrast,
s often
entered n
more equitable and productive landscape settings
(Seabloom
et al.
2002,
Huston
2005).
Consequently,
the
unprotected ortions
of
ecosystems
ftencontain
habitats crucial for
organisms
hat reside within
he
protected
reas for
ortions
f the
year.
ntenseanduse
may
be
disproportionately
enteredon these
unpro-
tected rucialhabitats
Hansen
and Rotella
2002).
Seasonal
and
migration
habitats. Animals
often
move across the
andscape
easonally
o obtain
required
resources. or
protected
reas at
higher
levations,
ey
winter
ranges
are often outside the boundaries of
protected
reas.
Similarly,
rotected
reas
in
more arid
regions
ften o not containwet-season abitats.Land
usemayalter heseunprotectedeasonal habitats r the
movement
athways
etween easonal habitats.
Populations
of several
arge-mammal pecies
within
the Maasai Mara
Reserve nd AmboseliNational Park
in
Kenya
have declined
n
abundance
during
he
past
30
years
n the face of
rapid
ntensificationf land use
in
the
urroundingegions
A.
J.Hansen et
al.,
unpublished
report).
f
the 15
species
nalyzed,
ight
pecies
n
the
Massai Mara Reserve
and one
species
in
Amboseli
declined
ignificantlyuring
his ime.The declineswere
severe or
everal
pecies
nd
ranged
rom .7% to 2.5%
of the
population
size
per
annum. These
population
changes
were
statistically
ssociated with human use
factors in the wet-season habitats outside of the
protected
rea
boundaries.
n
tropical
orests f
Borneo,
Indonesia,
long-distance
migrations
f bearded
pigs
have been
disrupted
y
the
ogging
f the
dipterocarp
trees
whose fruits re
prime
food sources for the
pigs
(Curran
t al.
1999).
Berger
2004)
documented hat he
225-km
movement orridor
for
pronghorn
ntelope
(Antilocapra
mericana)
betweensummer nd winter
range
n GreaterYellowstone
passes
through
1 km
wide
bottleneck
hat s now threatened
ithnatural
gas
development.
Population
ource-sink abitats.
The crucialhabitats
outside of
protected
reas
may
be
especially
rich
in
resources nd may act as population source areas.
These habitats
may
allow
subpopulations
o
produce
surplus offspring
hat
disperse
to less
productive
habitats
n
protected
reas and allow
persistence
f the
subpopulations
n
the
reserves. or
example,
Hansen
and Rotella
(2002)
found
that bird
populations
n the
Greater Yellowstone
Ecosystem
were concentrated
n
small
hotspots
n
productive,
owland
settings
utside
protected
areas.
These source habitats
have been
disproportionately
sed for
griculture
nd rural
home
sites
(Gude
et al.
2007).
This
intense
and use has
converted these low-elevation source areas
for the
populations
to sink areas and
reduced the
viability
of
subpopulations
n
the more
marginal
habitats n
protected
reas.
Similarly,
Arcese and
Sinclair
1997)
suggested
hatmostof
Serengeti
ational
Park s a
sink
for he ion
population
nd that
he
pecies
s
maintained
there
because of
connectivity
ith
the
Ngorongoro
Conservation
Area,
which s a
population
ource area
for ion.
The
migratory
ovements f
many
organisms
cross
greaterecosystems
re
often
quite
obvious
to
park
managers
and local
people.
Hence,
the
problem
of
unprotected
easonal habitats
has
received
onsiderable
attention n
many
regions.
Designation
nd
protection
of
migration
orridors s
increasingly
idely
used to
minimize r
mitigate
onflicts
etween
human and use
and
migrating
ildlife
e.g.,
Miller t al.
2001).
Proximity
o
humans
Human
presence
n the
periphery
f
protected
reas
may
cause
changes
n
ecosystem
rocesses
nd
biodiver-
sity hat xtend arying istancesnto heprotectedrea
(Fig.
le).
Some of these
edge
effects
esult
n
habitat
change.
For
example,
learing
f forests
o the
edge
of
the
protected
area
boundary may
lead to
elevated
disturbance ates and
high
levels of
forest
mortality
within he forest
eserve
Laurance
et
al.
2000).
Other
types
of
edge
effects o not
cause
visible
changes
in
habitat,
but
have
strong
influences n
organisms
n
protected
reas
nonetheless.
unting
nd
poaching
often xtend
the
footprint
f human settle-
ments nto
adjacent
protected
reas
(Escamilla
et al.
2000,
Revilla et al.
2001).
For
example,
n the western
border of
Serengeti
National
Park,
poaching
was
estimated oextend pto 25km nto hepark Campbell
and Hofer
1995).
Exotic
organisms
nd disease
lso
may
spread
fromborder ommunitiesnto
protected
reas.
Bison
{Bison bison)
in
Yellowstone
National Park
contracted
rucellosis
while
ommingling
ith
ivestock
in
winter
range
outside of the
park
(Yellowstone
National
Park
1997).
This has led to a
substantial
management hallenge
now thatthe disease has been
largely
radicated
from
ivestockherds
n
the
United
States.
Similarly,
ions in
Serengeti
National
Park
underwent ramatic
opulation
eclines rom
he anine
distemper
hat
they
contracted
from
domestic
dogs
living
outside the
park
(Packer
et al.
1999).
Human
recreation is sometimeselevated near borders of
protected
areas and
may displace
wildlife
Hansen
et al.
2005).
Many
of these
edge
effects re
proportional
o the
density
f
the
adjacent
human
population
Woodroffe
and
Ginsberg
998,
Brashares
t
al.
2001).
Hence,
these
effects
may
be increased under human
population
growth
round
protected
reas.
Implications or
Conservation and
Management
This frameworkf
mechanisms
inking
and use with
protected
areas can
enhance the
various
ongoing
conservation nd
management pproaches.
The frame-
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984 INVITED FEATURE
Ecological
Applications
Vol.
17,
No. 4
Table 3.
Criteria or
managing egional
andscapes
to reduce the
mpacts
of land use
change
outside
of
protected
reas
on
ecologicalprocesses
nd
biodiversity
ithin eserves.
Mechanism
Type
Design
criteria
Change
n effective
ize of reserve
species-area
ffect;
minimum
ynamic
rea;
trophic
maximize
rea of functional
structure
habitats
Changes
n
ecological
flows nto disturbancenitiation nd run-out
ones;
placement
identify
nd maintain
cological
and out of reserve in watershed r airshed process ones
Loss of crucialhabitat utsideof
ephemeral
abitats;
ispersal
r
migration
abitats;
maintain
eymigration
nd
reserve
population
ource inkhabitats
sourcehabitats
Increased
xposure
o human
poaching;displacement;
xotics/disease manage
human
proximity
nd
activity
t
reserve
dge
edge
effects
work
provides
conceptual
basis for:
1)
mapping
he
boundariesof the effective
cosystem
ncompassing
protected
rea;
(2)
monitoring
nd
assessingmanage-
ment
ffectiveness;
3)
systematic
onservation
lanning
and
management
f the effective
cosystem;
nd
(4)
assessingvulnerability
f
protected
reas to land use
change.We willdiscuss ach of these pplications.
Ecosystem
oundaries
Managers
need to
be able to
quantify
he boundaries
of the ffective
cosystem
ncompassing protected
rea
in
order to know where
to monitor and use
change,
assess
management
ffectiveness,
nd
implement egion-
al
conservation
trategies
o maintain
he
protected
rea.
The
ecosystem
oundaries hould nclude he reas that
are
strongly
connected to the
protected
area in
ecological
processes
or
organism
movements and
population
processes.
The mechanisms
framework
provides
a
conceptual
basis for
mapping
these con-
nections nd identifyingheboundaries f the effective
ecosystem.
he area of
seminatural abitats ontribut-
ing
to effective
cosystem
ize can be
mapped using
remote-sensing
echniques
Rogan
and Chen
2004).
The
spatial
and
temporaldynamics
f natural disturbance
regimes
can be
mapped
from historic records or
projected
with
omputer
imulationmodels
e.g.,
Baker
1989).
Movements of
organisms
can be
quantified
through
se of
telemetry
nd othermethods
e.g., Berger
2004).
Mapping
of
population processes
and
source-
sink
dynamics
equires
othfield tudies nd
simulation
modeling e.g.,
Hansen and Rotella
2002). Quantifica-
tion
of human
edge
effects an be
done
with human
surveys nd other ssessmentmethods Campbelland
Hoffer
995).
n
addition o these
uantitative
methods,
expert opinion
often will be
needed to delineate
ecologicallymeaningful
oundaries.
Management
ffectiveness
nd
monitoring
After a
period
of focus on
the creation of new
protected
reas,
many
managers
nd
conservationists
are
attending
o the assessment f how
well
existing
protected
reas are
working.
or
example,
the World
Commission
n Protected
reas
WCPA)
has
developed
a
six-step rocess
for
assessingmanagement
ffective-
ness.
The
process
begins
with
stablishing
he context
of
existing
values
and
threats,
progresses
through
planning
nd allocation of
resources
inputs),
nd,
as
a
result of
management
actions
(process),
eventually
produces goods
and services
outputs)
that result
n
impacts
or outcomes
Hockings
2003:826).
This
ap-
proach may
be based on results
f
questionnaires
f
managersnd other takeholders r on quantitativeata
from
ecological
measurement.
Our
frameworkof
mechanisms
rovides
a
conceptual
basis for
portions
of the
process.
Context an be
evaluated
by
assessing
threats rom
and use relative o the
places
and
processes
identified
n
our
ecological
mechanisms.
Planning
nd
management process
an
be aimed at
maintaining
he
connections nd functions
dentified
y
our mechanisms.
The
U.S.
National Park Service
and the Canadian
Park Service
Parks
Canada
Agency
2005)
have
each
established
nventory
nd
monitoring
I&M)
programs
aimed at
assessing
he
condition f
parks
nd determin-
ing management
ffectiveness.
ithin he U.S.
National
Park Service &M Program,ur mechanismsramework
has been used to
guide
selection
of
monitoring
indicators,
elimitate he
effective
cosystem,
nd
guide
analysis
of trends
n threats nd
ecological
response
(D.
A.
Jones t
al.,
unpublished
anuscript).
Regionalmanagement
It
is
apparent
hat
manyprotected
reas
may
become
degradedby
and use and other actors
ccurring
n the
unprotected
arts
of the
surrounding
cosystem.
hus,
maintaining
rotected
reas often
will
require
ome evel
of conservation-oriented
anagement
n the
unpro-
tected
portion
f
the
ecosystem. Systematic
onserva-
tionplanning Margulesand Pressey 000) provides
coordinated
pproach
for ssessment
nd
management
across
regional andscapes.
Our
mechanisms ramework
provides design
criteria
for
regional
management
(Table
3).
Knowledge
of land use
patterns,
he
spatial
dynamics
of these
ecological
mechanisms,
nd the
responses
f
ecological processesprovide
context o
identify
laces
n
the
unprotected arts
f the
cosystem
that re most ritical or
maintainingcological
function
within
protected
reas.
Management
hould focus
on
maintaining
ffective
cosystem
ize,
ecological process
zones,
rucialhabitats or
rganisms,
nd on
minimizing
negative
uman
dge
effects.
oupled
withunderstand-
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June 007 LAND USE CHANGE
AROUND PROTECTED AREAS
985
Table 4.
Varying
ffects f differentand
use
types
n
ecological
mechanisms
ltering
eserves.
Effective
Ecological
process
Crucial
Edge
Type
of and use
change
reserve ize
zones/flows
habitats
effects
Resource xtraction
Logging
x
xx
Mining x x
Poaching
x
Food
production
Subsistence
arming
x
Small-scale
arming
x
x
x
x
Large-scale
ommercial
arming
x
x
x
x
Recreation
Tourism
x
Infrastructure
Roads/other
ransport
x
x
Dams x
x
Residential/commercial
Settlements
x
Urban/suburban
x x x
x
Note:An x indicates hat landuse
type
s
likely
o nvoke he
pecified
cological
mechanism
and
to influence
cosystem
unction nd
biodiversity
ithin
rotected
reas.
ing
of the socioeconomic
dynamics
in
the
region
(DeFries
et al.
2007),
the
mechanisms
ffer
compre-
hensive
pproach
for
nderstanding
nd
managing
hese
vitallymportant egions
o maintain
cological
function
while
minimizing
negative impacts
on
surrounding
human
ommunities.
Vulnerabilityfprotected
reas to
surrounding
and
use
With imited esources
or
onservation,
t s
necessary
to identifyhich rotectedreas are mostvulnerableo
land use
change
so that
mitigation
trategies
an be
focused
n these reas
Wilson
t al.
2005).
Three lasses
of factorsthat
may
influence he
vulnerability
f a
protected
area
to land use intensification
re: the
ecological properties
f
the
protected
rea and sur-
rounding
cosystem;
he
type
and rates of land use
conversion
nd
intensification;
nd the
properties
f the
surrounding
uman communities.
We
suggest
hat the
most vulnerable
rotected
reas
will be those with he
following
haracteristics.
1)
The
protected
rea
is small or
poorly placed
relative o
minimum
ynamic
rea of
disturbance;
hape
of
species-area
curves;
biophysicalgradients
nd the
resulting
reas
of
organism
movements;
nd watershed
size.
2)
The
protected
rea is
in
close
proximity
o dense
human
populations,
ntense and use
in
critical
ortions
of the
cosystem,
r is
likely
o come n close
proximity
underfuture
and use
change.
3)
The
surrounding
uman
community
acks incen-
tives or resources
for
forwarding
cological
goals
of
protected
reas.
The
first
oint
follows rom
he
fact
that
the
spatial
extent
f
ecosystem rocesses
may
differ rom
lace
to
place.
For
example, patial
patterns
f
precipitation
ay
determine
whether
rganisms
migrate
over small
or
large
areas.
Thus,
the
key
to
assessingvulnerability
f
protected
reas
s to
evaluatenot the
bsolute ize of the
area,
but its size relative o
the effective
cosystem
t
exists within.
Quantitative
ssessmentof the
spatial
extent f
biophysical
actors,
ydrologic
lows,
istur-
bance,
and
organism
movements elative
o size and
location of the
protected
rea
provides
context
for
assessing
he
vulnerability
f the
protected
rea to land
use
change
n
the
unprotected ortion
f the
cosystem.
The
intensity
nd
type
of land
use
in
surrounding
lands also
differs
among
protected
areas. Parks
surrounded
y
intense and
uses,
such as
urban and
suburban,
are more vulnerable than
those set in a
wilderness ontext.
Also,
land use
types
differn
their
likely
nfluence n
protected
reas. Land uses such
as
commercial
armingmay
elicit all four of the
mecha-
nisms
previously
described,
whereas others such as
tourism r
poaching may
involve
single
mechanism
(Table 4).
The socioeconomic fabric of surroundinghuman
communities
robably
lso influences he
vulnerability
of
protected
reas. Protected reas located in areas
where
surrounding
ommunities
ely
on bushmeator
forest
products
are
likely
to be more vulnerable.
Protected reas also
vary
n
theenforcementf
policies
to
protect
eserves
Bruner
t al.
2001).
For
example,
elephantpopulations
fared better
n
African
ountries
thatwere ble to
control
oaching rior
o the
vory
an
in
the 1980s
Leakey
and Morell
2001).
Protected reas
surrounded
y
human
communities hat benefit
rom
them
may
be less vulnerable ue to a
higher
ikelihood
8/20/2019 Hansen and DeFries
http://slidepdf.com/reader/full/hansen-and-defries 14/16
986 INVITED FEATURE
EcologicalApplications
Vol.
17,
No.
4
of
regional-scale
management
o forward he
goals
of
the
protected
rea
(Rasker
and Hansen
2000).
Finally,
we
suggest
hat he onfluence
f
these
actors
has
a
larger
effect n the
protected
rea than
the
additiveeffect f the individualfactors.
With further
refinementnd
testing,
uch criteria ould
provide
a
basis forevaluating he global network f protected
areas and for
identifying
hose that
are
the
highest
priority
f conservation
ttention,
ased on
vulnerabil-
ity
to
land
use
change.
Within
regional
ontext,
he
principles
lso
can
be
applied
to
strategic
and use
management
o conserve lements
f the
andscape
most
crucial to reserve
unction,
hile
allowing
and use to
fulfill uman needs on those
portions
f
the
andscape
less crucial o
the
functioning
f reserves.
The case studies in this Invited Feature
provide
examples
of
regional
assessments and
management
implications
round several
protected
reas
in
varying
ecological
and socioeconomic
ettings.
he
concluding
paper by DeFries et al. (2007) explores n detail the
interactions
etween
protected
reas and
local
people
and
opportunities
or
chieving egional-scalemanage-
ment.
Acknowledgments
We thank he uthors nthe nvited eaturefor
timulating
discussions n nature eserve ssues.This workwas
supported
by
the NASA Land
Cover Land
Use
Program
NAG5-11158).
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