Forests and
their
Interactions
AP Environmental
Science
Types of Forests
 Any
area where trees cover more than
10% of land.
 Includes:
a. open savannas - < 20% ground cover
b. Closed canopy forest – tree crowns
overlap to cover most of the ground.
c. Primary forests: composed primarily of
native species
Reason why old forests are
important?
O.F. contain unique biological features w/:
 large live & dead trees
 a large variety of vegetation, insects
and animals species.
 Often home to rare species, threatened
species and endangered species of
plants and animals, making them
ecologically significant.
Types of Forests-Old Growth
Other names
include:
1. Virgin forests
2. Primary forests
3. Ancient forests
4. Primevil forests
Old Growth Forests
New Growth Forests
New Growth forests
Deforestation & Consequences
Cause of
deforestation?
Consequences!!
 Logging
 Erosion
industry
 Cattle ranching
 Farming
 Biofuel production
 Food production
(ie. palm oil)
 Water
Runoff
 Excess CO2
 Loss of biodiversity
 Loss of cultural &
historic values
Forest Canopies
 Upper
canopy
 Mid-canopy
 Lower Canopy
 http://www.canopyintheclouds.com/pan
os/elfinforest
Forest Fires
 Forest
Fire Management
 Nova Fires by Month 2000
Forest Fires-Hot Question

In Mediterranean climates like portions of
California, a wetter than normal winter often leads
to greater severity of fires following summer. This
paradox occurs because increased rain leads to…

A. Greater accumulation of chaparral biomass
B. Higher pollination of annual flowers
C. Greater recreational use of parklands
D. Greater erosion & damage to access roads
E. Decreased summer rainfall




Forest Protection Legislation
1. Debt for Nature Swap
2. Roadless Rule – Clinton Administration
3. Northwest Forest Plan to regulate
harvesting on about 9.9 million ha of
federal lands in Oregon, Washing and
northern California.
Question to ponder?
 The
largest area of old-growth forest in the
United States is located in:
A. Alaska
B. B. Montana
C. California
D. North Carolina
E. Michigan
Forest and Competition
 There
are several species interactions
within an ecosystem:
 1.
Competitive Exclusion Principle
 2. Resource Partitioning
 3. Ecological Niche
Competition Between Species
 This
type of interspecific competition:
– may occur when 2 or more species in community
use similar resources & those resources are in short
supply OR
- may limit the population growth of the competing
species
Intraspecific Interactions
– Relationships within the same species
1. Competitive Exclusion Principle
 Experiment
#1: Russian ecologist G. F. Gause studied
the effects of interspecific competition in two closely
related species of protists called Paramecium.
What do these results tell you about the interaction of
these 2 species?
Separate
cultures
Combined
cultures
P. aurelia
P. caudatum
 From
his research, Gause concluded that
two species so similar that they compete for
the same limiting resources cannot coexist in
the same place for any length of time.
 One species will always be more efficient
and adaptable:
….in getting food
….in reproducing
• Ecologists called this concept the
competitive exclusion principle
Ecological Niche:
a. Sum total of a species’ use of biotic
and abiotic resources in its environ
&
b. A species’ habitat & it’s job
(ex. Forest / producer)
• We can now restate the competitive
exclusion principle as follows:
Two species cannot coexist
in a community if their
niches are identical.
Resource PartitioningExperiment #1: Explain this example of resource
partitioning. How have the different species adapted
to their competition?
A. ricordii
A. ricordii
A. insolitus
A. insolitus
A. distichus
A. aliniger
A. christophei
A. distichus A. distichus
A. christophei
A. cybotes
A. cybotes
A. etheridgei A. etheridgei
A. insolitus
Figure 19.7
2. Resource Partitioning
 There are two possible outcomes of
competing species w/ identical niches (not
just living in the same area)
1. Extinction of one species
2. Evolution of one species to use a
different set of resources
Resource partitioning is the differentiation of
niches that enables similar species to coexist
in a community.
Reproductive Potential
…Is an organism’s
ability to grow at
the fastest rate.
(To replenish the
species—innate!)
REPRODUCTIVE
POTENTIAL COMPARISON
R-selected
Hint: Rapid Repro
a. Early reproduction
b. Short life span
c. Hi mortality
d. Little/no parental
care
e. Large # of offspring
produced
1.
2. K-selected
Hint: Longer Repro
a. Late reproduction
b. Long life span
c. Low mortality
d. High parental care
e. Small # of offspring
produced
REPRODUCTION TYPES
R-SELECTED
TYPES
K-SELECTED TYPE
Reproduction Connection
 Which
of the following is generally true of
a K-strategist species?
 A. They reach sexual maturity faster.
 B. They have more young.
 C. They are likely to be invasive species.
 D. They have longer life spans.
 E. Their populations cycles are more
rapid.
The Complexity of Community Networks
 The
interrelatedness of interactions between
species makes communities complex
Recruitment
Release of volatile
attractants
Chemical in
saliva
Wounding
Detection
by plant
Figure 19.17