disturbance

Question 1

what is disturbance?

Answer 1

a discrete event in time and space that alters the structure of populations, communities and ecosystems and causes changes in resource availability or the physical environment

ANY physical force that removes biomass from the community

Question 2

how is intensity measured?

Answer 2

• proportion of total biomass killed
• often inversely related to frequency
• how strong the force is

Question 3

how is frequency measured?

Answer 3

• number of disturbances in a given time interval
• determines how far succession can proceed
• annual patters

Question 4

what are the effects of disturbance?

Answer 4

• reduces population
• loss/modification of habitat
• changes condition e.g resources
• creates opps for other species
• drives increases in biodiversity by initiating succession of communities

Question 5

what the intermediate disturbance hypothesis (IDH) ?

Answer 5

proposes that species diversity is maximised at an intermediate level of disturbance

Question 6

what is heterogenity?

Answer 6

the variation in distribution of biotic and abiotic elements across space and time, is diseriable because the greater it is the more niches available

Question 7

what is resistance?

Answer 7

the ability of a community or ecosystem to
maintain structure and/or function in the face of potential disturbance.

Question 8

what is resilience?

Answer 8

the ability of a community or ecosystem to return to its original conditions following disturbance

Question 9

resillience mechanisms (forest fires)

Answer 9

• nutrient release to soil
• regrowth by seeds and roots
• invasions by neighboring undisturbed ecosystems (biodiversity benefits)
• rapid restoration of energy flow and nutrient cycling

Question 10

example of resistance/ resilience to disturbance

Answer 10

• bark thickness
• vegetative insulation
• re sprouting from epicormic buds
• below ground roots and underground stems

Question 11

what did Noble & Slayer develop and when?

Answer 11

1980 they developed -vital attribute system- to predict population responses to disturbance

Question 12

consequences of suppressing disturbances

Answer 12

mussel and sea palm

Question 13

what are the effects of fire suppression in Ponderosa pine forests?

Answer 13

changes the type of fires as more vegetation closer together
more intense fires kill more trees

Question 14

what percentage of digging species in Australia are now extinct?

Answer 14

50%!!!
they trap organic material and have higher fertility and soil moisture