ecological heterogeneity

what variations in biotic and abiotic components can occur in an ecosystem

differences or changes in environmental characteristics (rainfall, sunlight, nutrients, wind)

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relative concentration or distribution of organisms

define structural heterogeneity

the complexity and variability of a property of an ecosystem in three-dimensional space and over time

define spacial heterogeneity

different values of an ecosystem component in different places within an ecosystem; “patchy” distribution (e.g. plant cover, soil N values)

define temporal heterogeneity

change in values of an ecosystem component time (e.g. seasonal variation in precipitation, migratory species)

boundaries are a form of spatial heterogeneity, what is a type of boundary that can occur? and give examples of how they can be created

sharp boundaries

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created by fires, strong storms (hurricanes/tornados) and human impacts (clear-cutting) or changes from one ecotype to another (aquatic to the terrestrial boundary - like body of water)

what results in terms of the landscape after a forest fire

fire kills/damages trees in patches

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resulting in patches with differences in vegetation & soil properties (moisture, nutrients, pH, etc.)

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sharp boundaries between then affected and unaffected areas

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exchange across the boundaries affects the ecological structure and function of the patches

can a highway be considered spatial heterogeneity

yes

what conditions can differ across a boundary

light, moisture, wind, aerosols, nutrient availability, biota etc.

is this considered an example of the boundaries created through spatial heterogeneity:

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in deserts, abiotic and biotic conditions (organic matter content of soils, nutrients, moisture, wind, temperature, predation, etc.) can differ under plants vs in exposed areas

yes, it is still different values of an ecosystem in different places with patchy boundaries

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some species can live in the patches, some can live between the patches

what is an example of a natural cause of heterogeneity

forest fire mosaics

pit and mound microtopography

true or false: due to advancements in technology, wild fires are more easily controllable therefore the acres burned from these fires has drastically increased

FALSE: the acres burned has increased a lot while the number of fires per year has remained constant

define pit and mound microtopography

large tree falls due to wind, snow or the inexorable forces of time

after 5-10 years, a mound forms as the root mass decays

where the roots get ripped up, creates a pit

earthworms move in

create microenvironment

define ecological extinction

when a species is still present, but in such a small population that they don’t have any ecological significance or an impact on other species

with smaller fragmented areas, would that mean a more likely cause for extinction or proliferation of the species

more likely to have extinction

species richness is low

what are edges?

they are where different adjacent plant communities intersect

define brood parasitism. what bird is more likely to suffer from this and why?

when birds put their eggs into other birds nests

passerine birds suffer from this since they are nesting in edge zones and cowbirds are likely to do this

true or false: birds typically like to nest deep in the forrest not the edges, since theres less wind, its less exposed and more hidden from predators so theyre less likely to be eaten

TRUE

where is the bacteria reservoir of lyme disease

a. deer

b. birds

c. white footed mice

d. tics

c

where do white footed mice thrive

in small forest fragments and on the edge habitats

where are you most likely to find white footed mice

a. rural areas

b. urban areas

c. suburban areas

a

define gradients in spatial heterogeneity

give an example

continuous variation in ecological factors

ex. mountain slopes, coastal environments, rivers

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think of river system and varying degrees of nutrients (stream orders)!

define fragmentation

a reduction in the area covered by a habitat type

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a change in the habitat configuration with the remaining habitat apportioned into smaller more isolated patches

what are the four types of landscapes

intact

variegated

fragmented

relict

define intact landscapes

most of the original vegetations with little or no loss

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>90% remain from original

define variegated landscapes

mostly dominated by the original vegetation

define fragmented landscapes

fragments are minor components of the landscape dominated by other land uses

define relict landscapes

urban or intense agriculture

which of these has the highest degree of connectivity

a. intact landscape

b. variegated landscape

c. fragmented landscape

d. relict landscape

a

which of these landscapes has loss of original landscpae, but can still allow for movement of organisms between patches smoothly

a. intact landscape

b. variegated landscape

c. fragmented landscape

d. relict landscape

b

which of these has abrupt boundaries

a. intact landscape

b. variegated landscape

c. fragmented landscape

d. relict landscape

b

which of these has a high degree of space between the patches (low connectivity)

a. intact landscape

b. variegated landscape

c. fragmented landscape

d. relict landscape

c

which of these has no connectivity

a. intact landscape

b. variegated landscape

c. fragmented landscape

d. relict landscape

d

what type(s) of species are usually the first lost during habitat loss

rare species

endemic species

define crowding effect

when a territory is isolated, the influx of migrants from displaced areas will increase population densities

would temperate and tropical species be more susceptible to fragmentation and insuralization?

no! they are more endemic and rare species so they will not deal with disturbacnes from humans well and will therefore be lost due to the changes caused to the habitat

with greater species richness in areas this means…

the ecosystem is more resistant to disturbance and can be more productive

what is a diel cycle

occurs over a 24 hr period

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tracks photosynthesis/ respiration (sunlight and temp)

tracks migration/movement (zooplankton, nocturnal/diurnal animals)

with annual variability measurements, what types of things are being measured

flood pulse

temp

precipitation

ice presence

net ecosystem respiration of carbon

GPP

ecosystem respiration

(all in different biomes over a year)

what does a disruption in ecosystems consist of

a disruption in ecosystems consists of disturbance and response

characterized by their temporal patterns

what are the types of disturnaces, give an example of each

pulse: sudden onset, short-lived, ends fast (ex. windstorm, seasonal disturbance, seasonal flooding etc.)

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press: once instigates remain in place a long time (ex. climate shift to a new regime)

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ramp: steady increase over time without an endpoint (ex. acid rain, eutrophication, drought)

what are the responses that can occur due to disturbances

resistance = a measure of the capacity of a system to withstand a disturbance

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resilience = a measure of the capacity of the system to recover from disturbance

define succession

the gradual change in biological communities in an area following a disturbance or the creation of a new geological substrate

what are the two types of succession

primary = occurs on newly exposed geological substrate

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secondary = occurs after a disturbance destroys the biological community but does not destroy the soil

would it be easier for the ecosystem to bounce back from secondary or primary succession

secondary since the soil is still intact

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primary rips up everything, and you start from scratch

briefly describe the process of secondary succession

theres an **undisturbed ecosystem**

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\*\*\*disturbance\*\*\*

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causes sharp decline

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following the disturbance, the ecosystem **reorganizes** (0-20 years… forest loses biomass, water, and nutrients)

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**aggradation** occurs (100+ years) biomass starts to accumulate (water and nutrients are strongly retained - LOTS)

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transition phase occurs, biomass declines from peak(loss of nutrients and increase in water)

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steady state phase - biomass is between a steady fluctuation of a mean value

what is the transition phase of the secondary succession model considered

a. press response

b. ramp response

c. pulse response

b

what is the steady state phase of the secondary succession model considered

a. press response

b. ramp response

c. pulse response

a

what is the reorganization phase of the secondary successtion model considered

a. press response

b. ramp response

c. pulse response

c