BIOMES
Biomes and climate associations
A. Forest Biomes
1. tropical rainforests: light and nutrient competition
key: (found in tropical wet climate having no dry
season or a short dry season)
3 or 4 "tiers"
the "jungle" myth and the dark floor
slash and burn agriculture
found on trade wind coasts, areas dominated by
ITCZ
the ecotone: zone of transition between biomes
2. tropical seasonal forests: caused by a
significant dry season (which can be cool if at
elevation), often located where ITCZ movement
creates a wet season
3. midlatitude (temperate) forests: wet summers,
typically in interior of continents up to or near east
coasts
-lose leaves due to cold, inability to
photosynthesize, self-protection
-ground layer veg. richest in spring…why?
-pines (coniferous) are found in drier soil areas
and often burned areas (pine bark more
resistant), thus pine not a "climax species"
4. Mediterranean forest and scrub: pines and oaks
(woodlands) (CA)
mild, rainy winter, hot dry summer (mid latitude
west coasts, summers dominated by high
pressure)
5. boreal forest (COLD)
-coniferous trees: needles begin photosynthesis
rapidly
transpiration low from small, waxy needles (soil
may be frozen)
6. Temperate rainforest (W. Coast N. America)
conifers dominate, mild winters, highly productive,
greatest biomass of any forest
B. Grassland Biomes
1. Savanna (tropical grasslands) rainy season in
high sun season, generally found just poleward of
tropical forests, fire can increase productivity
2. midlatitude grassland
Today’s most productive farmland soils
C. Tundra and Mountain Biomes “read up, please”
D Desert Biomes - xerophytes:
adaptations to aridity:
1. deep roots or roots with great areal coverage
2. waxy and/or small leaves
3. bark capable of photosynthesis
4. water storage
5. short annual life cycle
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(optional) Ocean Environments
-warm water continental shelves: great
species diversity, coral reefs
-coastal upwelling (near west coasts): very
productive (nutrient sources)
open ocean: less productive…why?