Disturbance and Succesion Flashcards
Disturbance
a discreet event in time that causes abrubt changes in community structure and resource levels
What is a disturbance regime characterized by?
disturbance type
frequency
intensity
extent
recovery from distubrance = ________
succession
Disturbance type
Abiotic
Biotic
Anthropgenic
Abiotic disturbance
Severe weather
geological events
fire
flooding
biotic disturbance
animal activity
anthropogenic disturbance
human caused disturbances
disturbance frequency
typical time between disturbances (ex: fire intervals are between 50 and 200+ year depending on site)
Disturbance intensity
proportion of biomass removed and plants killed
recovery time is generally _______ correlatated with intensity
negativly
Disturbance extent (size)
area impacted by a single disturbance event
Which dsturbances are easiest to manage?
severity and extent
Succession
progressive change in the dominant species in a community, often following disturbance
unit of succesion
sere
general trends in succession
increased biomass
more complex physiognomy
more nutrients held in biomass
greater organic matter
Primary succession
Succession on raw soil parent material
secondary succession
succession on existing soil and generally some in-situ surviving propagules
mechanisms of succession
the biotic or abiotic process that cause changes in vegetation
Succession pathway or model
conceptual construct of succesion describing the temporal pattern of vegetation
Small scale succession example
ground squirrel burrows
stand replacing disturbances
plant life is leveled
partial disturbances
certain speces are taken out
small scale gap disturbances
small area disturbed
example of large scale succession
glacial retreat
successioin pathway
initial lichen-forb stage
dryas dominated
intermediate alder stage
sitka spruce forest
major changes through succession
soil organic matter and nitrogen levels increase
succession ________ always follow the same trajectory
does not
