Temperature Constraints Flashcards
What are limiting factors?
Environmental conditions that limit the growth, abundance, and distribution of organisms
Organisms experience physiological stress at niche margins, along a limiting factor
What is the law of tolerance?
Species have optimal survival conditions within environmental thresholds
Beyond this range, the rate of survival decreases
What is a macroclimate?
Large-scale climate patterns that prevail over entire regions
Determined by climate cells and topography
What is a microclimate?
Small-scale climate patterns at an area
Can deviate from macroclimate patterns
Determined by landscape, vegetation or small-scale topography features, such as elevation, mountain aspect, vegetation, etc
How does elevation influence microclimate?
Timberline on a mountain reflects a shift in microclimate
The temp decreases at higher elevations but trees need a certain temp to grow
How does aspect influence microclimate (north)?
Slopes exposed to the north receive less solar radiation, higher snow loads, and hence more water
Water availability = good for forest to grow
How does aspect influence microclimate (south)?
Slopes exposed to the south receive more solar radiation, lower snow loads, and hence less water
Water availability = bad for forest growth so grasses and shrubs prevail
How does vegetation influence microclimate?
By casting shade
In the understory, temps are cooler and evaporation is decreased
How does surface colour influence microclimate?
Lighter colours = reflect light, surroundings don’t increase in temp
Darker colours = absorb light, surroundings increase in temp
What is albedo?
The reflectivity of a landscape
How much light is reflected and does not get absorbed
Lighter = higher albedo
How do boulders and burrows influence microclimate?
Some organisms live under rocks or in burrows
They create shade and allow inhabiting animals to avoid heat
What are temperatures like in aquatic environments?
Water temperatures fluctuate much less than air temperatures on land
Only fluctuate between -4 to 32°
Why is water temperature stable?
Water has an higher capacity for absorbing heat energy without changing temperature than air
Heat is absorbed by water as it evaporates
Water gives up heat energy as it freezes
What is thawing and vaporization?
Energy absorbed as heat is supplied
Leads to intermittent, stable temperatures along a heat gradient
What is the range of tolerance in plants (temperature)?
Limiting factor of photosynthesis
What are evolutionary tradeoffs?
Adapting to one set of environmental conditions generally reduces fitness in other environments
What strategies do organisms have to deal with temp constraints?
Die
Migrate
Acclimate
Adapt
How do organisms cope with extreme temps with death?
Avoiding extreme temps by maximizing reproduction, followed by death
-annual plants
How do organisms cope with extreme temps with migration?
Avoiding extreme temps by migrating to distant regions
-birds
How do organisms cope with extreme temps with acclimatization?
Physiological or morphological changes in response to changes in the environment
-adjustment to elevation
What is the difference between acclimatization and adaptation?
Acclimatization is reversible and adaptation is not due to genetics
How do organisms cope with extreme temps with adaptation?
Hibernation
Estivation
Freeze tolerance
Thick fur, fat, short body appendages
What is the heat balance equation?
Hs=Hm±Hcd±Hcv±Hr-He
How have plants adapted to cold temps?
Dark coloured leaves
Cushion growth form
Leaf and flower orientation
Smaller surface-area ratio
