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Transcript
You’re welcome to linger in these woods.
Water sustains the entire Monongahela ecosystem.
ECOLOGICAL SUCCESSION
•
•
•
•
•
•
PROCESS OF CHANGE
OVER TIME
DIRECTIONAL
PREDICTABLE
END-POINT = CLIMAX STAGE
CLIMAX = STABLE, SELFPERPETUATING COMMUNITY
An autumnal umbrella arches above the
41-year-old forest stand.
Where it all ends up: Creeks in the Fernow Experimental Forest feed the
glistening Cheat River.
SUCCESSION CONCEPT
• IMPLIES SEQUENCE OF NEW SPECIES
OVER TIME
• MUST GET THERE--SOME FORM OF
DISPERSAL
– OVERCOME BARRIERS (LIST SEVERAL)
• COMPLETE LIFE CYCLE
• EFFECTIVELY REPODUCE/COMPETE
1
TYPES OF SUCCESSION
• NON-DIRECTIONAL
– CYCLIC--REPEATED SEQUENCE
• DIRECTIONAL
– PRIMARY SUCCESSION
• BARREN HABITAT (VOLCANIC ISLAND;
GLACIAL DEBRIS, ABANDONDED GRAVEL
PIT; NEWLY CREATED POND/LAKE)
– PIONEER SPECIES
• OPPORTUNISTIC COLONIZERS
PRIMARY SUCCESSION
• PRIMARY COLONIZERS
• MODIFY ENVIRONMENT TO ALLOW
FOR OTHER SPECIES TO BE BETTER
ABLE TO COMPETE/ESTABLISH THEIR
PRESENCE AT SITE
– NEW SPECIES OUT-COMPETE PRIMARY
COLONIZERS
– RESULTS IN CHANGE IN COMMUNITY
– CHANGE IN SPECIES COMPOSITION
PRIMARY SUCCESSION
• PRIMARY COLONIZERS--FIRST
ONE(s) THERE
– CHARACTERISTICS
• GOOD COMPETITORS
• REPRODUCE MANY OFFSPRING
• (r-SELECTIVE)
• SEVERAL (MANY) REPR. CYCLES/YEAR
• SMALL BODY SIZE
PRIMARY SUCCESSION
• PROCESS OF SEQUENTIAL CHANGE
• TAKES PLACE OVER TIME
• STAGES IDENTIFIED: SERES
(SERAL STAGES)
– OLD FIELD
– SHRUB
– FOREST
• PINE, OAK-HICKORY, BEACH-MAPLE
2
PRIMARY SUCCESSION
OAK-HICKORY FOREST @ LOESSEL BOG,
EASTERN MICHIGAN UNIVERSITY--1964
BEECH-MAPLE WOODLOT--CURTISS ROAD,
YPSILANTI, MI ca. FALL, 1964
CONTIGUOUS QUADRAT SAMPLING: OLD FIELD
PRIMARY SUCCESSION @ U of M BOTANICAL GARDENS,
JOHN DIX FIELD, ca 1966 (with Wm. S. BENNINGHOFF)
BEECH-MAPLE WOODLOT--CURTISS ROAD,
YPSILANTI, MI ca. FALL, 1964
VIRGIN BEECH-MAPLE FOREST,
PAOLIA, IN (FALL 1970)
3
SECONDARY SUCCESSION
VIRGIN BEECH-MAPLE FOREST,
PAOLIA, IN (FALL 1970)
• SIMILAR SEQUENCE AS PRIMARY;
STARTING POINT DIFFERENT
– SITE PREVIOUSLY OCCUPIED BY
ORGANISMS: ABANDONED FARMLAND
RESULTING IN OLD FIELD---FOREST
– SOME TYPE OF SOIL STRUCTURE
PRESENT
• FARMING, LOGGING, FIRE, WINDS
– DISTURBANCE LEAVING SOME
SOIL/OTHER ORGANISMS
SECONDARY
SUCCESSION
OAK TUBES: Plastic tubes protect oak seedlings from
grazing deer, whose numbers are unusually high due to
population declines among their natural predators: mountain
lions and coyotes. Oaks are prized as timber and for the
diversity of wildlife they support, but their numbers are
dwindling in the forests of the eastern United States. Their
decline is a mystery to rangers and scientists.
This forest stand was cut two years ago.
Site1/view2
Site 1/view1
FOREST FLOOR: Birds, bears, and other animals carried
seeds to this spot. The seeds lay dormant on the ground
Site 1/
awaiting an opening in the canopy to admit daylight.
view3
Clearing the plot provided that opening. Now blackberries,
grapevines, and wildflowers spring up amid a sea of new
green life. Animals will eat the fruit and renew the cycle.
4
STUMP: Without direct sunlight to dry them, stumps in this
plot remain damp through most of the year. The moisture Site 2/
view1
hastens their decay. Mosses, among the most primitive
plants, thrive on the rotting wood. So do fungi such as
mushrooms, which spread by spores borne on the wind or
via tendrils beneath the ground.
FOREST FLOOR: Except for patches of moss, almost
nothing green survives on the ground. It is brown and
mottled with fallen leaves. As they deepen and decompose,
they mix with minerals from the weathered bedrock below
to create a rich organic soil.
Site 2/
view 3
This forest stand was cut 41 years ago.
Site 3/
view 2
This forest stand was cut 12 years ago.
Site 2/
view 2
DEBRIS: Some trees, such as the fire cherry (which rarely
survives more than 40 years), have run their course and
toppled. The dead trunks of this tree litter the ground. Here
too are snags—standing trunks of dead trees. They draw
woodpeckers, which feast on the insects within them.
Squirrels and owls sometimes nest inside hollow snags.
Site 3/
view 1
TREES: Shade-tolerant beeches and sugar maples subsist
in the understory (above the ground but below the treetops)
on what light can reach them. The tallest survivors—rising to
heights of 90 feet (27 meters)—include hickories, red
maples, and yellow poplars. But no oaks. Sizable trees
number 600 per acre (1,500 per hectare).
Site 3/
view 3
5
This forest stand was cut about 86 years ago.
REBIRTH: No forest is ever finished. Even amid elderly
sentinals new plants grace the forest floor. For nature, wrote
Gerard Manley Hopkins, “is never spent.”
Site 4/
view 3
Site 4/
view 2
CLIMAX COMMUNITY
• STABLE
TREES: Vestigial oaks, the great providers of the eastern
forest, remain here in the oldest plot. Each supports
hundreds of other plant and animal species in microhabitats
within the limbs, along the trunk, inside the leaves, and
among the roots. These mature woods are home to about
125 large trees per acre (310 per hectare).
– SELF-PERPETUATING (REGENERATING)
– SPECIES ASSEMBLAGE IN EQUILIBRIUM
WITH ENVIRONMENT (BIOTIC/ABIOTIC)
– IN “HARMONY” WITH REGIONAL
CLIMATE AND SOIL TYPES
• CLIMAX PATTERN HYPOTHESIS
Site 4/
view 1
PIONEER COMMUNITY VS.
CLIMAX COMMUNITY
• SEQUENCE OF SUCCESSION--MARKED BY
STAGES CALLED SERES
– SERAL STAGES
• OLD FIELD
• SHRUB
• FOREST
• EXAMINE & COMPARE VARIOUS
CHARACTERISTICS OF TWO ENDS OF
SPECTRUM (PIONEER VS. CLIMAX)
– COMMUNITY ADAPTED TO TOTAL
PATTERN OF ENVIR. FACTORS
PIONEER COMMUNITY
• OPPORTUNISTIC SPECIES
– PRIMARY COLONIZERS
• EASILY OVERCOME DISPERSAL
BARRIERS
– DIFFUSION DISPERSAL
– JUMP DISPERSAL (LARGE BARRIERS_
• MOUNTAIN RANGES, DESERTS, OCEANS
6
PIONEER COMMUNITY
(CONT’D)
•
•
•
•
SMALL BODY SIZE
MANY OFFSPRING PER GENERATION
MANY GENERATIONS/YEAR/SEASON
INTENSE COMPETITION
– SIGNIFICANT NICHE OVERLAP
• LOW SPECIES DIVERSITY
– FEW SPECIES; MANY INDIVIDUALS
• r-SELECTIVE SPECIES
CLIMAX COMMUNITY (CONT’D)
• MULTIPLE ENVIRONMENTAL
FACTORS DEFINE SIZE & SHAPE OF
NICHE FOR A SPECIES
• SPECIES ADAPTATIONS HELP DEFINE
NICHE SPACE
• NICHE SPACE OF ONE SPECIES MAY
OVERLAP WITH ANOTHER
CLIMAX COMMUNITY
• END-POINT = CLIMAX
• STABLE
• HIGH SPECIES DIVERSITY
– MANY SPECIES
•
•
•
•
•
•
LOW COMPETITIVE INTERACTION
LIMITED NICHE OVERLAP
LARGE BODY SIZE
FEW OFFSPRING PER GENERATION
“ONE” REPRODUCTIVE CYCLE PER YEAR
K-SELECTIVE SPECIES
SPECIES DIVERSITY
(DEFINITION)
• TOTAL NUMBER OF SPECIES
IN A GIVEN AREA (PER UNIT
AREA)
– INTERACTION (COMPETITION)
SPECIES DIVERSITY:
(USES & APPLICATIONS)
• SPECIES DIVERSITY
– UNIQUE CHARACTERISTIC OF
COMMUNITY OR ECOSYSTEM
– QUANTIFIED ATTRIBUTE
– MEASURE OF COMPLEXITY AND
STABILITY OF HABITAT/ECOSYSTEM
– PRACTICAL USE: INDEX AS TO
SEVERITY OF POLLUTION
7
GEOGRAPHIC PATTERNS:
NOT ALL COMMUNITIES SAME
• NORTH-SOUTH LATITUDINAL GRADIENTS
–TERRESTRIAL
–AQUATIC
• FRESH WATER SYSTEMS
• OCEANS
• TOPOGRAPHIC RELIEF
–ALTITUDINAL TRENDS
–MNT. SYSTEMS-ROCKIES/APPALACHIANS HAVE
GREATER NUMBER THAN AVE. MAMMALS
LAVA FLOW
COOLING LAVA AFTER ERUPTION
VOLCANIC ISLAND
8
WHY HIGH SPECIES DIVERSITY
PATTERNS?? DO TO...
NUMBER OF
SPECIES
ON SURTSEY, A
NEW ISLAND
•
•
•
•
COMPLEXITY OF HABITAT
DIVERSITY OF HABITAT
RESULT IN MORE DIVERSE NICHE SPACE
MORE NICHE SPACE--MORE SPECIES ARE
ABLE TO OCCUPY NICHE SPACE
• IF SPECIES “LEARN” TO PARTITION
RESOURCES
WHY?? (CONT’D)
• TROPICS HAVE GREATER “EVENNESS” IN
CLIMATE--FEWER EXTREMES (TEMP)
• LONGER GROWING SEASON
• LONGER HISTORY...LESS AFFECTED BY
GLACIAL ACTIVITY
• GREATER HABITAT DIVERSITY...LEADS
TO GREATER NUMBER OF NICHES
• HIGHER SPECIES DIVERSITY/MORE STABLE
BEECH-MAPLE WOODLOT--CURTISS ROAD,
YPSILANTI, MI ca. FALL, 1964
CLIMAX COMMUNITY
STABILITY
• HIGHER SPECIES DIVERSITY
• EVOLVED TO CONDITIONS WITH LESS
DIRECT COMPETITION
• GREATER RESOURCE PARTITIONING
• MORE SPECIES...HIGHER STABILITY OF
COMMUNITY STRUCTURE
VIRGIN BEECH-MAPLE FOREST,
PAOLIA, IN (FALL 1970)
9
VIRGIN BEECH-MAPLE FOREST,
PAOLIA, IN (FALL 1970)
NICHE CONCEPT:
FUNCTIONALITY
• GIVEN: EACH SPECIES HAS ITS
OWN TIME & PLACE IN
COMMUNITY, DIFFERENT FROM
OTHER SPECIES--INTEREST IN
CONCEPT
• HABITAT
• NICHE
SPECIES INTERACTIONS &
CONCEPT OF NICHE
• HABITAT = WHERE ORGANISM LIVES
• NICHE = ROLE/JOB OF ORGANISM IN
COMMUNITY (FUNCTION)
– PRODUCER, CONSUMER, DECOMPOSER
• NICHE = SPATIAL POSITION IN HABITAT
– DEFINED BY MULTIPLE ENVIRONMENTAL
FACTORS
HABITAT
• KIND OF ENVIRONMENT IN WHICH
SPECIES IS FOUND
– DESCRIBE IN TERMS OF PHYS/CHEM
ASPECTS OF SETTING
– TOPOGRAPHY
– SPECIES COMPOSITION
• SINGLE SPECIES MAY OCCUPY A
RANGE OF DIFFERENT HABITATS
HABITAT
NICHE
• DIFFERENT SPECIES MAY OCCUPY
SIMILAR HABITATS
• APPLIED TO DEFINE THE DEGREE
OR MANNER OF SPECIALIZATION
OF SPECIES IN A PARTICULAR
HABITAT
– BOTTOM DWELLERS (CRABS,
LOBSTERS, ETC)
• ECOLOGICAL EQUIALENTS OR
ECOLOGICAL COUNTERPARTS
• DIFFERENT SPECIES FILLING SIMILAR
HABITATS GEOGRAPHICALLY
– FUNCTIONAL RELATIONSHIPS TO
OTHER SPECIES
–SPACE
–TIME
10
NICHE
• DEFINED AS THE SPECIES POSITION IN THE
COMMUNITY
• A NUMBER OF NICHES IN AN AREA MEANS
A HIGHER DEGREE OF SPECIALIZATION OF
SPECIES REPRESENTED
• DEFINES AN EVOLUTIONARY/GENETIC
FUNCTION WITHIN SPECIES COMPLEX
NICHE:
SPATIAL CONCEPT
– TIME, ENVIRONMENTAL CONDITIONS ARE
STIMULI
SPATIAL CONCEPT OF
NICHE
SPECIES INTERACTIONS
• SPACING PATTERNS
• G.E. HUTCHINSON (1957), A YALE
SCHOLAR: “THE NICHE IS AN
ABSTRACTLY INHABITED
HYPERVOLUME”
• CONCEPT OF DIMENSIONALITY OF
CONTROL FACTORS
• FUNDAMENTAL VS. REALIZED NICHE
– RANDOM
– CLUMPED (AGGREGATION)
– EVENLY SPACED--REGULAR-(HYPERDISPERSION)
• EVALUATE TYPE OF DISPERSION
(DISTRIBUTION) BY POISSON
STATISTICS
SPECIES DISTRIBUTION PATTERNS
11
TYPES OF COMPETITION
• INTRASPECIFIC COMPETITION
– INTERACTIONS BETWEEN INDIVIDUALS
OF SAME SPECIES
• INTERSPECIFIC COMPETITION
– INTERACTIONS BETWEEN INDIVIDUALS
OF DIFFERENT SPECIES
•
HUMIDITY
NICHE
SPACE/OVERLAP
NICHE
SPACE/OVERLAP
•
HUMIDITY
SYMPATRIC DISTRIBUTION
SPECIES A
SPECIES A
ALLOPATRTIC
DISTRIBUTION
SPECIES B
TEMPERATURE
COMPETITIVE INTERACTION
• NO OVERLAP OF NICHE SPACE
– ALLOPATRIC DISTRIBUTION
– NO COMPETITION
• OVERLAP OF NICHE SPACE
SPECIES B
TEMPERATURE
– SYMPATRIC DISTRIBUTION
– DEGREE OF COMPETITION DEPENDS
UPON AMOUNT OF OVERLAP
– SPACE, TIME, SEASON, RESOURCE
USE
12
RESOURCE PARTITIONING
• PROCESS IN NATURE WHERE TWO
OR MORE SPECIES OCCUPY SAME
NICHE SPACE
FIGURES
ILLUSTRATE
EXTREMES IN
RESOURCE
PARTITIONING
SCHEME
% OF DIET
– SOME OF THE TIME
– COMPETE FOR SAME OR SIMILAR
RESOURCES
– SHARE RESOURCE & ALLOW FOR
MUTUAL EXISTENCE IN SAME NICHE
SPACE
FEEDING NICHE OF BLUE-GRAY GNATCATCHER
CAPTURE OF INSECT PREY
OF DIFFERENT SIZES TAKEN
AT DIFFERENT HEIGHTS
ABOVE THE GROUND
TERNS ON
CHRISTMAS
ISLAND
FISH BODY LENGT, CM
NICHE CONEPT: ISSUES OF
SPECIES CO-EXISTENCE
• CO-EXIST IF POPULATIONS SUBJECT TO
DIFFERENT CONTROLS (RESOURCE LIMITS OR
OTHER POPUL. REG. MECHANISMS)
• CO-EXIST IF OCCUPY DIFFERENT SPACES-DIFFERENT HABITATS WITHIN SAME GENERAL
AREA
• CO-EXIST WITHIN SAME COMMUNITY IF THEY
RELATE DIFFERENTLY TO RESOURCES AND/OR
OTHER SPECIES IN COMMUNITY
SPECIES CO-EXIST IN
STABLE COMMUNITY, IF:
• DIFFER IN HORIZONTAL & VERTICAL
POSITION
• TIME RELATIONS
• RESOURCE UTILIZATION
• KIND OF INTERACTION WITH OTHER
SPECIES OR IN THE MANNER OF
POPULATION CONTROL
13
FUNDAMENTAL NICHE: ALL
POSSIBLE PLACES/POSITIONS
OF SPECIES WITHIN HABITAT
• ENVIRONMENTAL CONTROL FACTORS
PROJECTED INTO n-DIMENSIONAL
SPACE
• DEGREE OF HYPERVOLUME (SPATIAL)
OVERLAP A FUNCTION OF
COMMONALITY OF VARIABLES
REALIZED NICHE
FUNDAMENTAL NICHE
• COMMUNITY NICHE RELATIONSHIPS
REFLECT n-DIMENSIONAL COMPONENTS
• EACH SPECIES HAS ITS OWN POSITION (OR
NICHE) WITH A CENTRAL LOCATION THAT
DIFFERS FROM OTHER SPECIES, BECAUSE
OF:
–EVOLUTIONARY PROCESSES (INCLUDING
REDUCED COMPETITION)
–LEADS TOWARD SCATTERING OR DISPERSION
OF SPECIES IN NICHE SPACE
FIVE (5) WARBLER SPECIES OCCUPYING
DIFFERENT NICHE SPACE IN CONIFER
• COMPETITIVE INTERACTION RESULTS IN
EITHER EXTINCTION OR CO-EXISTENCE
• COMPETITION PARTITIONS NICHE SPACE,
RESTRICTING SPECIES TO PART OF
FUNDAMENTAL NICHE
• THUS, REALIZED NICHE ACTUALLY
SMALLER IN SPATIAL EXTENT (VOLUME)
THAN FUNDAMENTAL NICHE
COMPETITIVE EXCLUSION
PRINCIPLE (GAUSE)
COMPETITIVE EXCLUSION
PRINCIPLE (GAUSE)
• IF TWO SPECIES OCCUPY THE SAME NICHE
IN THE SAME STABLE COMMUNITY, ONE
WILL BECOME EXTINCT
• NO TWO SPECIES OBSERVED IN STABLE
COMMUNITY ARE DIRECT COMPETITORS
LIMITED BY SAME RESOURCES
– THEY DIFFER IN NICHE REQUIREMENTS
IN WAYS THAT REDUCE COMPETITION
BETWEEN THEM
• NO TWO SPECIES MAY OCCUPY THE SAME
NICHE SPACE
– AT SAME TIME
– ALL OF TIME
– UTILIZING SAME RESOURCES
– AND SURVIVE
• OUTCOME: ONE OR BOTH BECOME
EXTINCT
14
COMPETITIVE EXCLUSION
(CONT’D)
• TWO SPECIES CANNOT COEXIST
INDEFINITELY IN SAME HABITAT IF
THEY REQUIRE IDENTICAL
RESOURCES (NICHE SPACE)
• ONE OR BOTH MAY BECOME EXTINCT
SPECIES CO-EXISTENCE
• NICHE SPACE OVERLAP
• RESOURCE PARTITIONING
• RESULTS IN MORE SPECIES IN SAME
HABITAT
• INCREASED SPECIES DIVERSITY
• INCREASED COMMUNITY STABILITY
– “COMMUNITY” SURVIVES IN FACE OF
ADVERSE ENVIRONMENTAL
CHANGE...TO A POINT
BIOMES
• MAJOR INTEGRATION OF ECOSYSTEMS ON
A LARGE SCALE
– OVER LARGE EXPANSE OF LANDSCAPE
• BIOMES CHARACTERIZED IN TERMS OF:
– VEGETATION
– CLIMATE
– SOIL TYPE
– ANIMALS
ALPINE TUNDRA
SEVEN MAJOR BIOMES:
•
•
•
•
•
•
TUNDRA
TIAGA (BOREAL/CONIFEROUS) FOREST
DESERT (HOT & COLD)
PRAIRIE
DECIDUOUS FOREST
TROPICAL RAIN FOREST
ALPINE LANDSCAPE--ABOVE TREELINE
15
ALPINE VEGETATION @ TREELINE
ALPINE VEGETATION @ TREELINE
ALPINE BOREAL FOREST--CLINGMANS DOME
PINE FOREST
IN NORTHERN
MICHIGAN
GRASSLAND--PRAIRIE VEGETATION
TALLGRASS PRAIRIE VEGETATION
16
DESERT
VEGETATION,
SOUTHERN
ARIZONA
DESERT
VEGETATION,
SOUTHERN
ARIZONA
SAND PLAINS VEGETATION: LONG LEAF PINE
(IN DEPRESSION) & TURKEY OAK
(ON RIM OF DEPRESSION) IN COASTAL PLAIN, NC
DESERT FLOWERS,
SOUTHERN
ARIZONA
TURKEY OAK
BOG MAT VEGETATION: NORTHERN MICHIGAN
BOG ORCHID: CALOPOGON
17
CATHEDRAL WOODLOT @ CMU--1977
LOOKING SOUTH-SOUTHEAST
EAST
CATHEDRAL WOODLOT @ CMU--1977
LOOKING EAST
VEIT’S OLD FIELD: SPECIES DIVERSITY MAP
BASED ON STUDY BY BAILEY & CHANEY
TOPOGRAPHIC
MAP OF VEIT’S
OLD FIELD
SHOWING
SAMPLE PLOTS
18