Honors Biology
Ch. 3
Communities,
Biomes, and
Ecosystems
I. Limiting Factors
- factors that affect an organism's
ability to survive in its environment
- temperature, rainfall, fire, food,
predators, etc.
A. Optimum Range:
- area with least limiting factors
B. Zone of Physiological Stress:
- area with a few limiting factors
C. Zone of Intolerance:
- area where limiting factor is outside
the range of tolerance
Optimum Range
Optimum Range
Range of Tolerance
Distribution of
Douglas-fir
*
Microclimate
II. Ecological Succession
Mount St. Helens
explosion, 1980
Same view,
20 years later
II. Ecological Succession
- the replacement of one community
by another over time following
disturbance
- one community changes the physical
environment so that it can't survive
but another community can
A. Primary Succession:
- succession on land that has not been
previously occupied
- ex. lava, ash, bare rock
- Pioneer species: mosses, lichen (build soil)
Primary Succession
Succession in a Pond
(a)
(c)
(b)
Succession in a Pond
B. Secondary Succession
- reestablishment of an ecosystem
following disturbance (soil present)
- ex. forest fire, clearcutting, flood,
abandoned fields, hurricanes, mudslides
Secondary Succession
C. Climax Ecosystem
- a mature
community
(until next
disturbance)
C. Climax Ecosystem
- a mature community (until next
disturbance)
- occurs at the end of succession
- can regenerate itself (plants can
tolerate shade)
III. Biomes:
- large group of ecosystems with a
similar climate and dominant plant life
High (Temperature) Low
Climate Affects Biome Distribution
Dry
(Rainfall)
Wet
A. Terrestrial Biomes
- most important limiting factors are
temperature and precipitation
Terrestrial Biomes
Biome Map Key
Tundra
Boreal forest
Temperate Rainforest
Temperate forest
Grassland
Desert
Chaparral
Tropical Savanna
Tropical Rainforest
1. Tundra
Tundra
Treeless region < 10 in. rain annually
Permanently frozen soil (permafrost)
Very fragile, scars last for centuries
2. Boreal Forest (Taiga)
Boreal Forest (Taiga or
Northern Coniferous Forest)
Northern Canada
and Eurasia
Winters long & cold
Evergreen coniferous
trees with needlelike leaves
Plant & animal
diversity low
3. Temperate Deciduous Forests
Temperate Deciduous Forest
30-60 in. rain
annually, most
during summer
Mostly deciduous
trees, bare in
winter
Leaf litter on soil
High diversity of
animals
4. Chaparral
Chaparral
Often in coastal
regions bordering
deserts
Up to 30 in. rain
annually, but all
during cool months
Summers hot &
dry
Small trees &
large bushes
(Temperate Rain Forest)
Temperate Rain Forest
Abundant rain
Soil seldom
freezes
Usually coastal
5. Grasslands
Grassland
10-30 in. rain/year
Usually in centers of
continents
Shortgrass Prairie
No trees except by
rivers
Periodic droughts
Frequent fires
Most fertile soil in
world
Overgrazing problems
Sagebrush Desert or
Shortgrass Prairie
6. Deserts
Desert
Usually found
between 20-30°
N & S latitude
Less than 10 in.
rain/yr.
Boom & bust
population growth
after rain
Very fragile
ecology
Sonoran Desert
Arizona
Flowers indicate
recent rain
Saguaro cactus
unique to this
desert
7. Savanna
Savanna
Grasses dominate;
scattered trees
Short rainy season
<12 in. (30 cm)/year
Long, severe
droughts
African savanna with
many large animals
Many species in
danger of extinction
8. Tropical Seasonal Forest
Tropical Seasonal Forest
9. Tropical Rain Forest
Tropical Rain Forest
Temp 77-86 °F
Rainfall 100-160 in
Biodiversity: 50-67%
of all Earth’s species
6% of land area
40% now gone
- Losing 70 acres/min
> 2500 species go
extinct annually
Dominated by large,
broadleaf, evergreen,
complex forests
B. Aquatic Ecosystems
- major limiting abiotic factors:
distance from shore (nutrients),
salinity, depth (light), latitude
1. Freshwater Ecosystems:
- rivers, lakes, ponds,
groundwater
- < 1% of earth's
water
2. Transitional Aquatic Ecosystems
a.Wetlands
- marshes, swamps, bogs
Marsh
2. Transitional Aquatic Ecosystems
a.Wetlands
- marshes, swamps, bogs
Swamp
2. Transitional Aquatic Ecosystems
a.Wetlands
- marshes, swamps, bogs
Bog
2. Transitional Aquatic Ecosystems
b.Estuaries:
- boundary between fresh and salt water
2. Transitional Aquatic Ecosystems
b.Estuaries:
- boundary between fresh and salt water
- highly productive habitat for many
animals
- abundant nutrients and light
- "nursery" for many animals
3. Marine Ecosystems:
- vast and varied habitats
- light penetrates only 100 - 600 feet
(photic zone)
Intertidal
Zone
Neritic
Zone
Open
Ocean Photic
Zone Zone
Aphotic
Zone
Abyssal
Zone
Marine
Ecosystems
a. Intertidal Zone:
- harsh
environment:
tides, waves,
exposure to air
b. Open-Ocean Zone:
- low nutrients and fewer living
organisms
c. Neritic Zone:
- between low tide and open-sea
- abundant nutrients
- most productive marine environment
Coral Reef
Kelp Forest
1) Photic Zone:
- light penetrates up to 200m
2) Aphotic Zone:
- no light
3) Benthic Zone
- along the ocean floor
4) Abyssal Zone:
- extremely harsh
environment
- cold, dark, high
pressure
‘Black
Smoker’
4) Abyssal Zone:
- habitat for bizarre fish and other
animals
Fangtooth
Umbrellamouth
Gulper
Deep-sea Anglerfish
Ecosystem Productivity Compared
(Grams of biomass/meter2/year)
Tundra
(140)
Tropical
Rainforest
(2200)
Open
OceanNeritic
(125) (360)
Estuary
(1500)
Boreal
Forest
(800)
Temperate
Deciduous Forest
(1200)
Grassland
(600)
Desert
(90)
Projected Effect of Climate
Change on Forest Types
The
End