ENWC201 Lecture Notes - Lecture 10: Habitat Destruction, Habitat Fragmentation, Insular Biogeography
15 Jun 2018
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Habitat loss, degradation, and fragmentation
Habitat: the physical and biological resources required by an organism for
its survival and reproduction; these requirements are species-specific
As humans, we take natural lands and turn them into our own
habitat - drastic changes to plant biodiversity
Urbanization driving this loss
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Habitat loss, degradation, and fragmentation is the largest threat to
biodiversity and the leading cause of animal extinctions in the world
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Impacts many, but not all species
Habitat degradation: impacts many, but not all species and may be
temporary
Altering a habitat
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Habitat fragmentation: reduction in the area converted by habitat,
change in configuration
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Habitat loss: impacts so severe that almost all species are adversely
affected
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Habitat degradation
Can have many causes
Prime examples:
Livestock grazing
Rangelands ~25% of terrestrial land
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Invasive species
Create a monoculture where very few species can live
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Habitat fragmentation
The division of large habitat area into smaller patches
Smaller patches = less population stability and less biodiversity
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Island biogeography theory
As the lines cross you can see how many animals will be supported
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Edge effects: (effects that penetrate into the forest)
Air and soil temperature, moisture, light
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Vegetation density
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Predator intrusion
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Community composition
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Edge effects aren't negative or positive, just different
Different species like edge vs interior□
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Smaller patches = more edge, less interior per km squared
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Irregular shape = more edge, less interior per km squared
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Not all edges are created equal….
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The matrix = the surrounding landscape of fragmented habitat
Can impact what happens in the patch
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Example 1 - interior forest birds, nest parasitism
Edge and nesting□
Nest parasite
The more of these birds that have to nest on the edge,
the more they are victim to nest parasitism
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Example 2 - florida panther
Barrier from moving to the mainland to the island
Animal cant make it across
Getting hit by cars
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~100-150 left in the wild□
32 killed by cars in 2016 (record, old record = 25)
28 in 2017
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"the death, along a stretch of U.S. 41 East that is infamous as
a roadkill hot spot, orphaned possibly two panther kittens,
about 9 months old, Jansen reported. They likely will not
survive for more than a few weeks without their mother, who
had a radio-tracking collar to monitor her and her kittens"
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Connectivity and proximity
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Habitat loss
Lets look at 2 types:
Urbanization
Urban sprawl
Unplanned, uncontrolled spreading of urban
development to areas adjoining edges of cities
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A.
Conversion
When human activities transform one habitat type into
another
Native habitat to agriculture or pasture
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Management (i.e. damming or fire suppression)
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Example 1: greater prairie chicken□
Example 2: wetlands
Very important, helps maintain:
Water quality
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Water quantity
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Bank stabilization
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Wildlife habitat
Fish nurseries
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Food and energy for the entire ecosystem
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More productive than most other land types
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Chesapeake bay watershed
Rain from this area goes into the Chesapeake bay
Most diverse bay, supports all type of life
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60% loss of historical wetlands around the
watershed
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Southeast louisiana land loss
tons of species use wetlands as their breeding
grounds
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B.
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Thresholds in response to habitat loss are likely
How much habitat is enough?
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Difficult to predict
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We reach a tipping point where they will all die and go extinct - this
is the threshold
Reach a certain level of habitat loss that they cant tolerate□
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Humans are changing the earths surface beyond what we can imagine
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Habitat Loss
Sunday, April 15, 2018
11:08 PM
Document Summary
Habitat: the physical and biological resources required by an organism for its survival and reproduction; these requirements are species-specific. As humans, we take natural lands and turn them into our own habitat - drastic changes to plant biodiversity. Habitat loss, degradation, and fragmentation is the largest threat to biodiversity and the leading cause of animal extinctions in the world. Habitat degradation: impacts many, but not all species and may be temporary. Habitat fragmentation: reduction in the area converted by habitat, change in configuration. Habitat loss: impacts so severe that almost all species are adversely affected. Create a monoculture where very few species can live. The division of large habitat area into smaller patches. Smaller patches = less population stability and less biodiversity. As the lines cross you can see how many animals will be supported. Edge effects: (effects that penetrate into the forest) Edge effects aren"t negative or positive, just different.
