Topic 31/32 -Biomes

Question 1

biomes

Answer 1

basic community types occurring in a particular region, typically defined by the type of vegetation

Question 2

biomes are characterized by

Answer 2

climate (average annual precipitation vs average temperatures)

Question 3

transitions between biomes can be

Answer 3

gradual

Question 4

biomes do not function in

Answer 4

isolation

Question 5

Tropical rainforest

Answer 5

from equator to 20 degrees
high stable temperatures (25C) and annual rainfall (2000-4000mm)

supports largest biodiversity for landmass
882000lbsbiomass/hectare growing 75m
high degree of vertical structure -compete for light
most carbon is trapped in living organisms (37%)
soil is thin and low in nutrients
plants have access to plenty of water that may leech nutrients

Question 6

Tropical Savannah

Answer 6

20-30degrees N and S
high temps year round
seasonal precipitation (wet summer)
periodic fires, annual drought and flood plains and grazing favours growth of bunched grass species

relatively nutrient rich soils lead to early man colonizing and converting to agricultural practices

Question 7

Desert

Answer 7

two distinct bands at 30 N and S and some inland areas, 20% of land surface
characterized by high temps during the day but low levels of annual precipitation (highest 300mm)
some never get rain
evaporation exceeds precipitation

soil is gravel, rock or alkaline
algal, fungal or lichen mats can bind it in a fragile layer
vegetation grows sparsely
though abundance is low, diversity of species can be high in some areas due to high fluctuations in abiotic conditions

Question 8

temperate shrubland

Answer 8

30-40 degrees on every continent but Antarctica
termed chaparral in North America
dry summers and winter rain
plant species highly adapted for fires in dry summer climate
-underground storage organs and quick dispersal germination
sclerophyllous leaves= tough, leathery and stiff

limited agriculture capacity, converted to urban areas all over the world

Question 9

Temperate Grasslands

Answer 9

30-50 degrees
strong seasonality in temp and precipitation, both highest in summer
periodic fires and grazing wildlife promote grass and forb species similar to savannahs
meristems located underground as an adaption for grazers
deep roots stabilize and enrich soil “bread basket”

Question 10

Temperate Forests

Answer 10

Cold winter results in deciduous forests
coastally temperature rainforests exist with evergreen trees
soil in deciduous forests is enriched by decomposition of leaf litter
evergreen forests have nutrient poor acidic soils
not much of this biome remains -harvested for wood and paper, cleared for agriculture

Question 11

Boreal forest

Answer 11

about 50 degrees
insufficient land mass in south to support this biome
largest biome in area (1/3 earths forest)
precipitation is stable but long cold winters
highest temp range (-70 to 30C)
dominated by evergreen coniferous trees with needle-like leaves (also birch)
cone shaped of trees to adapted snow cover
same species occur across Northern hemisphere
thin, relatively infertile soils with slow decomposition rates
Permafrost= layer under the soil that stays frozen all year round
drainage of water prevented by permafrost
soils become saturated and periodic fires can melt permafrost and create peat bogs
Taiga=transition zone to tundra where eventually trees can no longer take root

Question 12

Tundra

Answer 12

mostly in the Arctic Circle (small amount on Antarctic Peninsula) beyond 65 degrees
extreme variation (24 hours of light in summer)
like desert, low precipitation (200-600mm)
precipitation exceeds evaporation
low perennial grasses, sedges, shrubs, mosses and lichens
rarely above 5cm and 2.200lbs/hectare
need to endure winds and annual freezing temps
heliotropic flowers- hairy leaves and stems (trichomes)

Question 13

Aquatic Biomes

Answer 13

unlike terrestrial biomes they are not as defined by vegetation, instead by:
Velocity (Lentic (still) Vs Lotic (flow)
temperature (often stratified)
clarity (light penetration is tantamount to the support of plant life)
Chemistry -salinity (freshwater vs marine)
-oxygen and nutrients
-pH

Question 14

Rivers and Streams

Answer 14

Freshwater
Lotic=water flows through the system
flow rate is an important determinant of the communities this biome can support

Plants and animals must be adapted to withstand current -firmly rooted, hide in less turbulent zones formed by debris on river bottom

Drain landscapes, often into oceans
streams organized into orders, two first order streams connect to make a second order stream (Nile is 6th order)
leads to different species composition

Question 15

Lakes and Ponds

Answer 15

Freshwater (typically)
lentic= water is stationary (non-flowing)
collections of water in natural depressions in the landscape
depending on depth can be thermally stratified like oceans: lake baikal ( 1600m)
photic zone: depth which light can penetrate and support plant life
some lakes are high saline (10x ocean) -Great Salt Lake, Utah

Question 16

Wetlands

Answer 16

Lentic systems formed from shallower depressions
Characterized by:
transient moisture levels ( high rate of succession)
low levels of decomposition due to low oxygen concentration
Function:
liver of the ecosystem, filter toxins and pollutants from surrounding land
natural flood plains

Question 17

Marshes

Answer 17

dominated by herbaceous plants

important breeding grounds for water fowl

Question 18

swamps

Answer 18

dominated by woody plants

on every continent besides Antarctica

Question 19

Bogs

Answer 19

Secluded to northern region
floating mats of sphagnum moss
“peatlands”

Question 20

4 Coastal Communities

Answer 20

Estuaries
Rocky intertidalzones
kelp forests
coral reefs

Question 21

Estuaries

Answer 21

vertical gradients of salinity where ocean water sinks below incoming freshwater flowing from rivers
gradual slope of landscape buffers incoming tides
ultimate aquatic edge habitat (supports high diversity)

Question 22

rocky intertidal zones

Answer 22

on sloping rock shores between average low and high tie levels
dominated by algal and invertebrate species that can: adhere to substrate and survive periods of dessication

Question 23

kelp forests

Answer 23

found along temperate coasts

form an underwater “forest-like system”

Question 24

coral reefs

Answer 24

tropical coasts (where water is 18C) 
similar to underwater "rainforest" ecosystem but supports even higher levels of diversity

Question 25

Open Oceans

Answer 25

traditionally thought as desert-like wastelands
only 1% of harvested fish stocks come from the open oceans
Nearly all primary production comes from phytoplankton (algae, dinoflagellates, diatoms)
some floating islands of Sargassum seaweed form discreet communities in the open ocean
pelagic=living in the water column
benthic= living on ocean floor
divided by depth

Question 26

Hyperthermal Vent communities

Answer 26

In reality the ocean supports far more phyla of animals than the terrestrial environment
Deep sea species adapt to life under significant pressure
the largest unexplored area on earth
Hydrothermal vent communities:
also have to adapt to extreme temps
-intense heat from vents, otherwise temp at this depth is nearly 0
Primary production from chemosynthesis
utilizing sulphur in place of oxygen and thermal energy from vents