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Species-of-the-Week
Wood Duck (Aix sponsa)
Brink of Extinction
By early 1900’s, culminative effects of:
1) wetland drainage (ag. expansion)
2) deforestation
3) overhunting
Habitat
• Wooded swamps &
river bottomlands
• Natural tree cavities for
nesting (cypress,
sycamore, silver maple,
black ash)
• Home range changes
with flooding events
Food
* In water <18”, feed on:
- seeds of trees (e.g.,
acorns)
- also field grains
* Young = aquatic
insects
Reproduction
Pairing in late Oct into
spring (Mar-July nest)
Clutch size = 6-10 eggs
Behavior
- Dump nests (up to 30+
eggs in 1 nest) = “egg
dumping” behavior =
intraspecific brood
parasitism
- may decrease hatch rates
to 10%
Factors Determining Patterns of
Habitat Use
Concept of Habitat Selection
• Wildlife perceiving correct configuration of
habitat needed for survival – differences based
on age/experience/chance? –
• Niche concept
Concept of Habitat Selection
• Hutchison = n-dimensional hypervolume as
explanation of the niche
• Fundamental vs. Realized Niche
Species 1
Species 2
Testing the Hutchinsonian Niche
Concept of Habitat Selection
• James – work with birds in
Arkansas…quantified habitat relationships
• How do birds select habitat?
• niche gestalt :
Wildlife Habitat Ecology & Mgt
• Habitat from an evolutionary perspective
• Species distribution relative to habitat dist’n
• Climatic events
• Pleistocene Epoch & dist’n of modern species
habitat interspersion –
Leopold’s Law of Interspersion
Habitat Fragmentation
1) gap formation
2) decrease patch
size
3) increase isolation
4) increase edge
5) conversion of
matrix
Concepts
• Habitat = species-specific resources
available (relative quality)
• Habitat Use = manner in which species
use resources
• Habitat Selection = hierarchical decision
process (innate & learned) of what
habitats to use
• Habitat Preference = based on selection
of habitat, which are used more than
others (preferred vs. avoided)
Concepts
• Habitat Availability = accessibility of
resources
• Habitat Quality = positive relation with
fitness (not just density)
• Critical Habitat = resources essential to
the species….ESA designation….
1st order – innate?
2nd order –decisions
3rd &4th order
–decisions
Scale Dependence
of Habitat Selection
1st Order
2nd Order
3rd Order
4th Order
Macrohabitat
vs.
Microhabitat
Guild Concept
• guild = group of species that exploit the
same class of resources in similar way
• community guild = no taxonomic
restrictions; guild members chosen
based on investigator-defined
resources
• assemblage guild = guild members
based on taxonomic relations
Models of Habitat Relationships
• Model (assess) habitat for wildlife
species, e.g., USFWS
• Habitat Suitability Index (HSI)
models
- include top 3 environmental
variables related to a species’
presence, distribution, &
abundance
HSI = (V1 x V2 x V3)1/3 = 0 to 1
• Yellow
Warbler HSI
for different
forest
conditions
HSI models
• useful for representing possible major
habitat factors
• true value as hypotheses
• Do not provide information on:
- population size or trend
- behavioral responses
• single-species approach
Emergence of Landscape Ecology
?
Equilibrium View
Structure
?
?
Function
?
• Constant species
composition
• Disturbance & succession =
subordinate factors
• Ecosystems self-contained
• Internal dynamics shape
trajectory
• No need to look outside
boundaries to understand
ecosystem dynamics
Emergence of Landscape Ecology
Dynamic View
Structure
Function
• Disturbance & ecosystem
response = key factors
• Disturbance counter
equilibrium
• Ecosystems NOT selfcontained
• Multiple scales of processes,
outside & inside
• Essential to examine spatial
& temporal context
Scale
• What’s the big deal?
• Seminal pubs
– Allen & Starr (1982) – Hierarchy: perspectives
for ecological complexity
– Delcourt et al. (1983) – Quaternary Science
Review 1:153-175
– O’Neill et al. (1986) – A hierarchical concept of
ecosystems
Long
Ecological Scaling: Scale & Pattern
Speciation
Extinction
Short
Temporal Scale
Species
Migrations
Secondary
Succession
Windthrow
Fire
Treefalls
Recruitment
Fine
Spatial Scale
Coarse
• Acts in the “ecological
theatre (Hutchinson
1965) are played out
across various scales
of space & time
• To understand these
dramas, one must
select the appropriate
scale
Ecological Scaling: Scale & Pattern
• Different patterns emerge,
depending on the scale of
investigation
Regional Scale
(thousands of ha)
American Redstart
American Redstart
Local Scale
(4 ha plots)
Least Flycatcher
Least Flycatcher
Ecological Scaling: Components of Scale
• Grain: minimum
resolution of the data
– Cell size (raster data)
– Min. polygon size
(vector data)
• Extent: scope or
domain of the data
– Size of landscape or
study area
Ecological Scale
• Scale characterized
by:
– grain: smallest
spatial resolution of
data
e.g., grid cell size,
pixel size,
quadrat size
(resolution)
Fine
Coarse
Ecological Scale
• Scale
characterized by:
– extent: size of
overall study area
(scope or domain
of the data)
Small
Large
Ecological Scaling: Components of Scale
• Minimum Patch Size:
min. size considered >
resolution of data
(defined by grain)
Ecological Scaling: Definitions
• Ecological scale & cartographic scale are exactly opposite
– Ecological scale = size (extent) of landscape
– Cartographic scale = ratio of map to real distance
Scale in
Ecology & Geography
• ecological vs. cartographic scale
Small
(Fine)
Large
(Broad)
Ecology
Geography
Fine resolution
Small Extent
Coarse resolution
Large extent
Coarse resolution
Large Extent
Fine resolution
Small extent
Scale in
Ecology & Geography
• ecological vs. cartographic scale
– e.g., map scale
1:24,000 vs. 1:3,000
fine vs. coarse
large vs. small extent
1:24,000
1:200,000
Ecological Scaling: Components of Scale
• Grain and extent are
correlated
• Information content
often correlated with
grain
• Grain and extent set
lower and upper limits
of resolution in the
data, respectively.
Ecological Scaling: Components of Scale
• From an organismcentered perspective,
grain and extent may
be defined as the
degree of acuity of a
stationary organism
with respect to shortand long-range
perceptual ability
Ecological Scaling: Components of Scale
• Grain = finest
component of
environment that can be
differentiated up close
• Extent = range at which
a relevant object can be
distinguished from a
fixed vantage point
Extent
Grain
Fine
Scale
Coarse
Ecological Scaling: Components of Scale
• From an anthropocentric
perspective, grain and
extent may be defined on
the basis of management
objectives
• Grain = finest unit of mgt
(e.g., stand)
• Extent = total area under
management (e.g., forest)
Ecological Scaling: Components of Scale
• In practice, grain and extent often dictated by scale of
available spatial data (e.g., imagery), logistics, or
technical capabilities
Ecological Scaling: Components of Scale
• Critical that grain and extent be defined for a study and
represent ecological phenomenon or organism studied.
• Otherwise, patterns detected have little meaning and/or
conclusions could be wrong
Scale: Jargon
• scale vs. level of organization
Individual
Space - Time
Population
Space - Time
Community
Space - Time
Ecological Scaling: Implications of Scale
• As one changes scale, statistical relationships may
change:
– Magnitude or sign of correlations
– Importance of variables
– Variance relationships
Implications of Changes in Scale
• Processes and/or patterns may change
• Hierarchy theory = structural
understanding of scale-dependent
phenomena
Example
Abundance of forest insects sampled at different distance
Intervals in leaf litter,
Implications of Changes in Scale
Insects sampled at 10-m intervals for 100 m
45
40
35
30
25
Predator
Prey
20
15
Pr
ey
Pr
ed
at
or
10
5
0
Implications of Changes in Scale
Insects sampled at 2000-m intervals for 20,000 m
45
40
35
30
25
Predator
Prey
20
15
Pr
ey
Pr
ed
at
or
10
5
0
Identifying the “Right” Scale(s)
•
•
•
•
No clear algorithm for defining
Autocorrelation & Independence
Life history correlates
Dependent on objectives and organisms
• Multiscale analysis!
• e.g., Australian leadbeater’s possum
Multiscale Analysis
• Species-specific perception of
landscape features : scale-dependent
– e.g., mesopredators in Indiana
• Modeling species distributions in
fragmented landscapes
Hierarchy Theory
• Lower levels
provide mechanistic
explanations
• Higher levels
provide constraints
Scale & Hierarchy Theory
• Hierarchical structure of systems =
helps us explain phenomena
–Why?
: next lower level
–So What? : next higher level
• minimum 3 hierarchical levels needed
Constraints
(significance)
Level of Focus
(level of interest)
Components
(explanation)