Download Community Ecology Ch 6 - Pendleton

Species Interactions &
Community Ecology
Chapter 6
HIGHER
TROPHIC
LEVELS
Complex array
of carnivores,
omnivores and
other
consumers.
Many feed at
more than one
trophic level
continually,
seasonally, or
when an
opportunity
presents itself
Typical Food Web
MARSH HAWK
CROW
UPLAND
SANDPIPER
GARTER SNAKE
FROG
SPIDER
SECOND
TROPHIC
LEVEL Primary
consumers
(e.g.,
herbivores)
FIRST TROPHIC
LEVEL
Primary
producers
WEASEL
CLAYCOLORED
SPARROW
EARTHWORMS, INSECTS (E.G.,
PRAIRIE VOLE
GRASSHOPPPERS,
CUTWORMS)
BADGER
POCKET
GOPHER
COYOTE
GROUND SQUIRREL
1. Maple seedling growing under an oak tree
2. Fungus (mycorrhizae) live on plant roots and
facilitate water absorption
3. Frog eats a fly
4. Your dog has fleas
5. A bacteria grown in culture produces toxins that
prevent others from growing near it
6. A hermit crab uses a discarded snail shell for
protection
Competitive Exclusion Principle:
•
When 2 species compete the more fit
one will win. Two species cannot coexist
in the same habitat with the same
requirements for very long.
•
Ex: gray squirrel vs red squirrel
It’s Squirrel
versus Squirrel!
How can all these species coexist?
NICHES!
• They can coexist if they utilize resources
under different environmental conditions.
• Niche: the role a species plays in its
habitat and under what environmental
conditions.
• Fundamental Niche: conditions species
can exist w/o competition.
• Realized Niche: conditions species can
exist with competition. (Real world!)
Where do they belong?
• Endemic species
– Native to a particular area and not elsewhere
• Exotic/non-native species
– Introduced into a new geographic area
• Invasive species
– Exotic that can run an endemic out of its habitat
• Cosmopolitan species
– Broad distribution in suitable environments
• Ubiquitous species
– They’re everywhere!
Pigeon
Mouse
Rabbits of Australia
Lorius Lory of New Guinea
Japanese Maple in NJ
Feral Rabbits in Australia, 1963
Introduced in 1859. Diseases like myxomatosis(1991) and rabbit
hemorrhagic disease (1996) were introduced in to control their numbers.
Has lead to genetic resistance (esp myxomatosis)
Ecological Succession
Restoration
Previous Ideas on Restoration:
• “Balance of Nature” Idea (until mid 20th century)
• Equilibrium: nature left alone will achieve a
permanency of form & structure forever—the
climax state.
• When there is a disturbance and then the force
is removed, nature will return to its former,
identical state.
• There’s a place for every creature and every
creature in its place.
• Disturbance is bad…
But now…
• Nature is not constant.
• All ecosystems continually undergo
change.
• Species evolve and adapt to change
• Many species require change to survive
To What Point Do We Restore?
• Pre-settlement of humans
• Restoration ecology
• Florida Everglades
– Restoring wetlands
– Improving water quality
– Improving habitats of 60+ endangered
species
• Midwestern Prairies
How do we restore it?
• Depends on the situation.
• Redirecting water flow (adding/removing
channels, dredging)
• Leave it alone/improve what goes into it
• Controlled burning
Succession:
• Natural recovery of a disturbed ecosystem.
• Primary: initial establishment & development of
an ecosystem where one did not previously
exist. Originally an abiotic environment. Ex:
edges of lava flows, receding glaciers
• Secondary: reestablishment of an ecosystem
following a disturbance. Some life will still
remain. Ex: areas of fire or hurricane,
abandoned farmland.
Primary Succession on a lava
flow. Pioneer species had
already taken hold
Secondary succession:
boreal forest after a fire
Stages of Succession
• Early: plants with short life cycles, rapid seed
dispersal. Stablize soil (aka 1st and 2nd
stages). Often annual plants that can tolerate
harsher conditions (much water, full sun, limited
water, etc)
– Biomass & Biodiversity both increase.
• Middle (3rd stage); larger plants, trees begin to
dominate once early stage plants have made
conditions more livable. Highest biodiversity
• Late (4th stage): Large, mature plants, larger
animals. Slower growing, grow well in shade,
have seeds that can persist.
Chemical cycling during
succession:
• Organic material & other chemicals in soil
increase throughout succession, but not
indefinitely.
• If there is no disturbance, the ecosystem
will use up stored chemicals and will no
longer support late stage plants.
Biomes
• Regional complex of similar communities
• Dominant plant types & structure
Precipitation, Latitude and Biomes
http://www.globalchange.umich.edu
Temperate Deciduous Forest
Oaks, Beech, Maple; moderate temps & rain
Temperate Grasslands
(steppe, prairie)
Tall grasses; less rainfall, more extreme temps between seasons
Temperate Rainforest
Hoh Rain Forest of
Washington State;
Conifers such as
cedars, spruce,
hemlock, Douglas
fir.
Heavy rainfall,
moderate temps
Tropical Rain Forest
Warm temps year round; heavy rainfall; closer to equator.
Poor soils, high diversity of species
Tropical Deciduous Forest
(Tropical Dry Forest)
Warm year-round
w/moderate rainfall
Can have Monsoon
seasons
Leaves may drop
during dry seasons
Savanna
Warm year round; dry. Grasses
Deserts
Sparse rainfall
May have large daily temp
fluctuations
Plants w/small-no leaves
Tundra
Very dry, cooler temps; extremely
cold in winter
Permafrost
Lichens, scrubby vegetation
Taiga
(Boreal Forest)
Small evergreens
Long cold winters, short cool summers, moderate rain
Chaparral
Mild wet winters, warm dry summers.
Mediterranean climate
Frequent fires
World’s Biomes