Brief Review. Game species (Leopold 1933) Biophysics in wind tunnels & fields (50s-70s) Vegetation responses (50s – present) Wildlife population (30s – present) Microclimate (late 80s – present) Ecosystem processes: very rare. - PowerPoint PPT Presentation
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Brief Review Brief Review •Game species (Leopold 1933) •Biophysics in wind tunnels & fields (50s-70s) •Vegetation responses (50s – present) •Wildlife population (30s – present) •Microclimate (late 80s – present) Productivity of tropical forests Productivity of tropical forests declined by about 36% as a result of declined by about 36% as a result of edge creation edge creation ( ( Laurance et al. 1997, Laurance et al. 1997, Science Science ) )
Transcript
Brief ReviewBrief Review•Game species (Leopold 1933)
•Biophysics in wind tunnels & fields (50s-70s)
•Vegetation responses (50s – present)
•Wildlife population (30s – present)
•Microclimate (late 80s – present)
•Ecosystem processes: very rare
Productivity of tropical forests declined by about 36% Productivity of tropical forests declined by about 36% as a result of edge creationas a result of edge creation ( (Laurance et al. 1997, Laurance et al. 1997, ScienceScience))
Forman (1995): Membranes TheoryForman (1995): Membranes Theory
““The cellular membrane is an intriguing and useful The cellular membrane is an intriguing and useful model to understand landscape boundaries (edges)… “model to understand landscape boundaries (edges)… “
““The inner and outer surfaces (of the membrane) differ The inner and outer surfaces (of the membrane) differ markedly”.markedly”.
“… “… The landscape boundary exhibits these functions and The landscape boundary exhibits these functions and more.”more.”
Frontiers in Edge StudyFrontiers in Edge Study
• Edge effects of two Edge effects of two sides are not sides are not sympatric;sympatric;
• The maximum The maximum edge effect does edge effect does not always occur not always occur at 0 m.at 0 m.
High
Low
High
Low
Rel
ati v
e A
bu
nd
ance
(a) Edge Species
1
2
3
edge
Distance from Edge
(b) Interior Species
1
2
3
edge
4
Euskirchen et al. (2001)
(a) Edge Species
Distance from Edge(a) Interior Species
Distance from Edge
EdgeEdgeVsVs
InteriorInteriorSpeciesSpecies
Within the area-of-edge Within the area-of-edge influence (AEI), most areas influence (AEI), most areas are under multiple edge are under multiple edge effects!effects!
Frontiers in Edge StudyFrontiers in Edge Study
Distribution of area-of-edge Distribution of area-of-edge influences (AEI) around older influences (AEI) around older clearcut, showing a complex AEI clearcut, showing a complex AEI composition.composition.
Proportion of AEI (%)
Jack Pine
0
20
40
60Proportion of AEI (%)
Mixed hardwood
0
20
40
60Proportion of AEI (%)
Red pine
0
20
40
60Proportion of AEI (%)
Old Clearcut
Composition of AEI around 4 patch types in the CNFComposition of AEI around 4 patch types in the CNF
Interior
Area of Edge Influence(AEI)
800 m
(84%)
So what?
Assuming the depth of edge Assuming the depth of edge influence is 240 m, a 50 ha influence is 240 m, a 50 ha (125 acre) forested patch (125 acre) forested patch surrounded by open area surrounded by open area contains very little interior contains very little interior environment. Indeed, 84% environment. Indeed, 84% of the forest is AEI.of the forest is AEI.
Fragmentation of Continental U.S. Forests(43.5% of forest land is within 90 m of forest edge)
Delaware River Basin
Ohio
Riitters and others, 2002, from Birdsey and colleagues
Forest Fragmentation of the Delaware River BasinForest Fragmentation of the Delaware River Basin
Delaware Water Gap NRA
• Derived from National Land Cover Data, 1992
• Northern half of river basin appears to be mostly interior forest
• Southern half of river basin appears to be mostly forest patches
Birdsey and colleagues
Climate Change and the Carbon Cycle: Biomass and Productivity of Areas with
Fragmented vs. Interior Forests
Predominance of interior forest
Predominance of fragmented forest
Birdsey and colleagues
Biomass for Areas of Fragmented vs. Interior Forests
Forest condition:
Mean biomass: (Mg/ha)
Interior 296.7
Fragmented 327.4
Birdsey and colleagues
NPP for Areas of Fragmented vs. Interior Forests
Forest condition:
Mean NPP: (g/m2)
Interior 1208.6
Fragmented 1250.0
Birdsey and colleagues
Continue to Continue to develop empirical develop empirical database on edge database on edge structure and structure and composition. composition.
Frontiers in Frontiers in Edge StudyEdge Study
Determining depth-of-edge influence continue to pose a Determining depth-of-edge influence continue to pose a major challenge.major challenge.
Chen et al. (2002) Chen et al. (2002) proposed the 1proposed the 1stst method. Other method. Other Critical Values Critical Values Program for Program for Assessing Edge Assessing Edge Influences can be Influences can be found at Harper & found at Harper & MacDonald (2002), MacDonald (2002), Bulletin of ESA.Bulletin of ESA.
Our knowledge on net carbon exchange of Our knowledge on net carbon exchange of agricultural landscapes is very limited.agricultural landscapes is very limited.
““Generalist species are more likely to be found along Generalist species are more likely to be found along edges or ecotones that are avoided by specialist species”edges or ecotones that are avoided by specialist species”
AR
UV
-100 -50 0 50 100
02
04
06
0
PR
PU
-100 -50 0 50 100
02
04
0
CO
PE
-100 -50 0 50 100
02
04
0
RU
AL
-100 -50 0 50 100
02
06
0
CA
PE
2
-100 -50 0 50 100
04
08
0
VA
AN
-100 -50 0 50 100
02
06
0
SA
HU
-100 -50 0 50 100
04
08
0
PR
SE
-100 -50 0 50 100
02
06
0
VIO
LA
-100 -50 0 50 100
01
02
03
0
HIE
R
-100 -50 0 50 100
05
10
AS
SA
-100 -50 0 50 100
05
10
15
PIB
A
-100 -50 0 50 100
02
04
0
DA
SP
-100 -50 0 50 100
01
02
03
0
Distance from the Edge (m)
Species abundance across a Species abundance across a jack pine edge in N. WI.jack pine edge in N. WI.
x
y
Tree
ISO-POTENTIAL CONTOURS
m
Physical, biological, and ecological processes across edges. Physical, biological, and ecological processes across edges. One example is to mechanically model turbulence as function
of forest structure
Exposure PhysicalEnvironment
Damages
CommunityProcesses
CommunityProcesses
CommunityProcesses
GrowthMortalityRegenerationPredation
Energy FlowEvaportranspirationNutrient CyclingSoil respiration
Pollen & Seed dispersalHorizontal energy flowInvasionAerosols dispersalSounds transformation
light
Air temperature
Productivity DiversityHabitat Quality
Canopy Density Biomass
Snaps CWD Litter
Soil OM Roots Soil moisture
Humidity
Pro
cess
esS
tru
ctu
reF
un
ctio
n
Open Forest
Dir
ect
Ch
ang
es
Inf l
ue
nc
es
Fe
ed
ba
ckDirect and Direct and
indirect of edge indirect of edge influences on influences on ecological pattern ecological pattern and processes.and processes.
What What properties are properties are really really affected?affected?
Direct effects of edge creation:•Physical damage•Exchange of energy, matter, species
1° process responses: Productivity, evapotranspiration, nutrient cycling, decomposition, dispersal
1° structural responses: Canopy cover, tree density, biomass, downed wood
2° process responses: Recruitment, growth, mortality, reproduction
2° compositional responses:• Change in understory composition
Magnitude ofedge influence
Distance of edge influence
(a)
(b)
MEIDEI
MEIDEI
MEIDEI
Ellen Macdonald
if it was possible to draw little sketches of each of these it would be great
Research NeedResearch Need: Quantify the ecological responses to multiple edges, : Quantify the ecological responses to multiple edges, especially in highly fragmented landscapes.especially in highly fragmented landscapes.
Hansen et al. (Hansen et al. (in reviewin review). Biomass Accumulation Hypothesis). Biomass Accumulation Hypothesis
““The The Biomass Accumulation HypothesisBiomass Accumulation Hypothesis asserts that edge effects asserts that edge effects have the highest magnitude of influence in ecosystems that have the highest magnitude of influence in ecosystems that accumulate high levels of biomass.”accumulate high levels of biomass.”
NPP
Sta
nd
-re
pla
cin
g
Dis
turb
an
ce
Low
Fre
qu
en
t
High
Infr
eq
ue
nt
Solar radiation, Temperature, Precipitation, Soil Fertility
Biomass
Accumulation
NPP
Sta
nd
-re
pla
cin
g
Dis
turb
an
ce
Low
Fre
qu
en
t
High
Infr
eq
ue
nt
Solar radiation, Temperature, Precipitation, Soil Fertility
Biomass
Accumulation
Research NeedResearch Need: Design sound experiments to test various hypotheses : Design sound experiments to test various hypotheses to form a united theory on edge effects.to form a united theory on edge effects.
Questions?Questions?
Amount of area-of-edge-influence (AEI, %)
Old stand
Young stand
Age
Edge Exposure
north-facing
Low High
% ofInterior
NEP
50% Fragmentation
south-facing
decr
ease
NE
P in
AE
Is
min
max
positiveincr
ease
Hypothesized effects of edges on NEP within the AEI. Edge Hypothesized effects of edges on NEP within the AEI. Edge orientation and edge age will be the two most important factors orientation and edge age will be the two most important factors determining the changes in NEP and/or WUE within the AEIs. determining the changes in NEP and/or WUE within the AEIs.
Create as much edge as possible because wildlife is a product of the places where two habitats meet. This has been the management principle for both public & private land owners until mid-90s.
-- Aldo Leopold (1933)
The essential requirements of wildlife- food, cover, and water- will be maintained so as to provide optimum ‘edge effect’ and interspersion of habitat components in important wildlife areas.
-- BLM Manual 1603 (1973)
The law of dispersion and interspersion work together to show the forest manager how to increase wildlife populations associated with edge.
-- Thomas et al. (1979)
But increasing emphasis on plant and nongame wildlife conservation during the last two decades has revealed many characteristics of edges and ecotones are now considered undesirable.
-- Larry Harris (1988)
We must not conclude that creation of more edge in landscapes will always have a positive effect on wildlife …
DWDa and DWDv for the four edge sides (YR,MR, YO and MO). replicate 1, Δ replicate 2, and ● replicate 3▲
YR MR YO MOYR MR YO MO
Results: Forest function ( carbon pools) ~ AGTc
YR MR YO MO
AGTc(MG ha-1) for the four edge sides (YR,MR,YO and MO). Symbols represent the three replicates per edge side; replicate 1, Δ replicate 2, and ● replicate 3▲
ConclusionConclusion• This study indicates young edge sides have a DEI
of 5 m and mature edge sides have a DEI of 22 m for both forest structure and carbon pools.
• A 22 m DEI is comparable previous forest structure studies in mixed hardwood forests (Harper and McDonald 200x; Malack 199x).
Results: LAI & LMALAI and LMA for the four edge sides (YR,MR, YO and MO). ▲replicate 1, Δ replicate 2, and ● replicate 3
Opennessfull & opennesshalf (%) for the four edge sides (YR,MR, YO & MO). replicate 1, Δ replicate 2, and ● replicate 3▲
YR MR YO MO
Results: Forest function ( carbon pools) ~ Litterc
YR MR YO MOYR MR YO MO
Litterc (MG ha-1) for the four edge sides (YR,MR, YO and MO). Symbols represent the three replicates per edge side; replicate 1, Δ replicate 2, and ● ▲replicate 3
Results: Forest function ( carbon pools) ~ DWDc and Snagc
DWDc and Snagc (MG ha-1) for the four edge sides (YR,MR,YO and MO). Symbols represent the three replicates per edge side; ▲replicate 1, Δ replicate 2, and ● replicate 3
