Lecture 13 (chapter 11) Flashcards
Environmental variation
- In spite of their
variation, ecologists
have classification
schemes aggregate
ecological variation into
clusters with general
similarity of structure
and function of the organisms found there
What is a biome?
Bioms are: Clusters of ecosystems that have a general similarity in structure of the ecosystem
Where do they exist: Over an
extensive geographic
range, occurring
anywhere in the world
that environmental
conditions are suitable
- Biology of biomes is defined by climate
- We characterize biomes
by late-successional
vegetation and
characteristic animals
4 main biomes=
boreal forest:
Temperate grasslands
Tropical rainforest
- Not the particular species that are preset that defines them but the way the environment looks (morphological) or the dominant organisms of the area
Biomes are demined by climate
- Abiotic factors influence biomes
- Temperature on x-axis (goes hot to cold)
- Y axis = precipitation
- end up with a triangular distribution
- low precipitation in cold
- higher participation in warm
- warm and wet = tropical rain forest
warm and less wet tropical seasonal forest
desert
temperate forest is middle
tiger and tempera cold dry
Why do different parts of the world have different biomes?
- Biomes are defined by temperature
- earth is tilted at a 23 degree angle
the fact that it is tillted give rise to percipatation regimes and temperatures
Winter solstice:
Sun directly overhead
(90°) at Tropic of
Capricorn at midday
- vernal equinox:
Sun directly
overhead (90°) at
equator at midday
Summer solstice :
Sun directly overhead
(90°) at Tropic of
Cancer at midday
Autumnal equinox:
Sun directly overhead
(90°) at equator at
midday
Annual variation in day length corresponds with distance from the equator
- Warm air at the equator rises-cools - water molecules condense and it’ll rain
- This is why we have a tone of rain by the equator
- the air continues to rise past the rain clouds cools and shift back down to the earth 30 degrees south or north
- this precipitation gives rise to rain forests
Global distribution of deserts results from the
return of dry air near 30ºN and 30ºS
general climatic and precipitation
patterns at different latitudes
equator- apple percipitation
summer wet /winter dry
dry all seasons
wiinterwet summer dry
apple percipitation all seasons
sparse precipitation all year
Tundra
- High latitude biome
- Growing season too short to support trees
- dominate vegetation grasses lichen moses
not enough growth season for large vegetation - Low precipitation, low evapotranspiration
- Permafrost (layer of peet that can be frozen year round) prevents drainage
- Small shrubs, grasses, and sedges
ex.
Dominant large herbivore
in arctic tundra is
migratory caribou
Very short window of opportunity to breed there but still allows many
migratory birds to breed
in the arctic
Low biodiversity
Temperate zone
- Lies north of the topic of cancer south of capercorn
Temperate zones lie
between the Arctic /
Antarctic and the Tropics
of Cancer / Capricorn - Variable vegetation,
depending on latitude
and the pattern of
precipitation - Marked seasonal
variation is
commonplace
Boreal forest (taiga) look at figure 11.5
Dominated by coniferous
trees
* Spread across the
Northern Hemisphere
* Short but warm
summers
* Deciduous trees such as
aspen and birch after
disturbance such as fire
Temperate deciduous forest
- Cold short winters
- Summer warm and long
enough to support many
deciduous trees - In Canada, highest tree
diversity is in southern
Carolinean forests - High species richness is
common in southern
temperate deciduous
forest - lots diversity
Fall leaf coloration Why do we see this as a colourful and defining feature of this biome?
Yellow and orange colours in fall leaves are
carotenoids, unmasked by the breakdown of
chlorophyll
* The red colours are
anthocyanins, newly
produced in the fall as
protection (produced deliberately at this time)
* These colours are not a
incidental product of leaf
senescence
- Resorbing helpful nutrients from leaves to center of tree
Why are our forests so colourful?
** Read why does fall foliage turn so
red and fiery? It depends. New York
Times**
All leaf colour
* Photoprotection
hypothesis: red pigments
protect against the
harmful effects of light at
low temperatures
(protective pigment)
- Coevolution hypothesis:
red is a warning signal
toward insects migrating
to the trees in autumn
(warning symbol to bugs to try and stop them from laying their eggs on them
Temperate rainforest
Found only in western North America (only where rainfall if most abundant)
* Bountiful precipitation all year
* Mild winters (not quite as much snow as temperate disdace forest)
* Highest conifer diversity of all biomes
* Abundant moss epiphyte (plants growing on other plants)
Rain forest
At least 2 m of rainfall
Temperate grassland
Low annual precipitation
* Insufficient moisture to support forests
* Cold winters, hot
summers
* Fire and herbivores (bison) keep trees out in
the more humid regions (tallgrass prairie)
- Herbivores eat any of the big growth.
