Ruderal
A whole community can be ruderal. Can often remain stuck in fairly simple life history trait species. Potentially not great competitors. Tolerators of harsh conditions. Often early colonizers.
Colonizer
Moves to suitable unihabited (by another competitor species) habitat. Ex: PJ mo...
Ruderal - answer A whole community can be
ruderal. Can often remain stuck in fairly simple life
history trait species. Potentially not great
competitors. Tolerators of harsh conditions. Often
early colonizers.
Colonizer - answer Moves to suitable unihabited
(by another competitor species) habitat. Ex: PJ
moving into ponderosa land due to drought. There
can still be colonizers without disturbance.
Opportunistic - answer Waiting for the right time.
Any species could be opportunistic, but the more
adaptable/flexible a species can be, the more
opportunistic they can be.
Fugitive - answer Early colonizer that thrives in
early post-disturbance. Could be escaping from a
highly competitive area to an area with less
competition.
Invader - answer Does not have to equal invasive
species. Forest to a chaparral dominated
ecosystem is an example even.
,Pioneer - answer First species at a site. Initial
species post-disturbance. Potentially sets the
trajectory of the ecosystem.
What does Sousa say is wrong with the disturbance
definition "uncommon, irregular events that cause
abrupt structural changes in natural communities
and move them away from equilibrium conditions"
- answer - Few communities are in "equilibrium,"
and Change can vary in how large a disturbance is
How do you characterize disturbance? - answer
Important to include it all. MFDPAS - Magnitude,
frequency, distribution, predictability, area, and
synergism
Magnitude - answer Intensity and Severity.
Intensity is the physical force of an event per area
per time. Severity is the impact on the organism,
community, and/or ecosystem
Frequency - answer Number of events per time
period. Can effect reproductive pattern, survival of
dominant species, growth form, and structure of
the community. IE: Historical spruce-fir fire regime
is about 700 years, whereas chaparral is 20-50
years.
,Distribution - answer Spatial arrangement of the
disturbance. Mosaics of successional or seral
patches. Can get complex very quickly.
Predictability - answer Turnover time. A key one for
how ecosystems are responding to disturbance.
Disturbance dependent systems have evolved to
anticipate repetitive disturbance. For example,
southern california chaparral has a 25 year return
time for fires, whereas spruce fir has 700 years.
Area (or size) - answer Total area/size of
disturbance. May be related to intensity and
frequency. Important to talk about heterogeneity
in the landscape. Think about how you're defining
the landscape. Such as fire and a mosaic of
different patches.
Synergism - answer Most disturbances do not
occur independently of each other
-Disturbances exert a synergistic selective
pressure on species populations that leads to
evolutionary change in ecosystem resilience
-They can have an influence on the likelihood or
severity of another
Ex; Bark beetles and fire
, Sousa reading - What two features characterize
natural communities? - answer They are dynamic
systems, the density and age-structure of
populations change with time and so does the
relative abundance of species. 2. Natural
communities are spatially heterogenous. True at
any scale of resolution, but especially at the
regional scale (more than one colonizable patch).
Mosaic of patches identified by spatial
discontinuities in the distributions of populations.
Sousa definition of disturbance - answer A
discrete, punctuated killing, displacement, or
damaging of one or more individuals (or colonies)
that directly or indirectly creates an opportunity
for new individuals (or colonies) to become
established.
Physical disturbance - answer Fires, ice storms,
floods, drought, high winds, landslides, large
waves, and desiccation stress
Biological disturbance - answer Encompass
everything from predation to grazing to non
predatory behaviors that inadvertently kill or
displace organisms.
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