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Chapter 25: Populations and Ecosystems - Coggle Diagram
Chapter 25: Populations and Ecosystems
Plants in Relationship to Their Habitats
habitat components
abiotic components
non-living
physical phenomena
climate
soil
latitude
altitude
disturbances
floods
avalanches
fires
common component of dry ecosystems
landslides
man-made disturbances
insecticides
herbicides
hunting
habitat destruction
climate
temperature
tolerance range
between high and low extremes of organism
rainfall (precipitation)
relative humidity
winds
soil factors
soil formed by breakdown of rock
all young soils deficient in nitrogen
pioneers
the first plants that invade a new soil
must tolerate severe conditions
often associated with nitrogen-fixing prokaryotes
horizons
A horizon
uppermost
sometimes called zone of leaching
consists of litter and debris
rainwater washes nutrients downward into
B horizon
zone of deposition
area where materials from the A horizon accumulate
rich in nutrients
contains both humus and clay
C horizon
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latitude and altitude
at the equator
all days are 12 hours long
no seasonal variation occurs in day length
plants cannot measure season by photoperiod
high latitudes (north and south)
summer days/winter nights progressively longer
biotic components
living factors
the plant itself
other plant species
mutualism
beneficial for both organisms
competition
two populations do not grow well together
competitive exclusion
whichever species is less adapted is exculded from ecosystem by superior competitors
compete for resources
light
soil nutrients
water
attention of pollinators and seed dispersers
niche
species adapted to a particular set of conditions
little competition occurs
ecotypes
subspecies who are specialized in response to particular ecosystem factors and its locality
transplant experiments
plants from each site are transplanted to alternate site
common garden
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animals
fungi
protists
prokaryotes
organisms other than plants
frugivores
fruit-eating animals that disperse seeds
ants
occupy acacia trees (in thorns) in Central America
ants protect tree (aggressive)
commensal relationships
one species benefits and the other is unaffected
birds nest in tree
sticky fruits or seeds
stick to animal fur or feathers
predation
one species benefits and the other is harmed
herbivores (process herbivory)
browsing/grazing
pathogenic
fungi or bacteria
The Structure of Populations
geographic distribution
boundaries of the geographic range
limiting factor
at any given time and locality one factor alone determines the health of the plant
any factor of ecosystem
both abiotic and biotic
local geographic distribution
random distribution
there is no obvious, identifiable pattern to the position of individuals
random pattern has no predictive value
clumped distributions
spacing between plants is either small or large, but rarely average
bird consumes many fruits/seeds
deposits them in a lump of organic fertilizer
uniform distributions
occur in orchards and tree plantations
all individuals are evenly spaced from their neighbors
not extremely common
interspecies competition
thought to be cause of natural even distribution
roots can establish a zone
prevents germination or growth of other plants
zones established (theoretically) by release of inhibitory chemicals
allelochemics
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purple salvias of California
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age distribution: demography
demography
the relative proportions of young, middle-aged, and old individuals
two factors affect the possible rate of population growth
generation time
the length of time from the birth of one individual until the birth of its first offspring
affects rapidity of population growth
annuals
generation time of 1 year or less
can increase rapidly
intrinsic rate of natural increase (biotic potential)
the number of offspring produced by an individual that actually live long enough to reproduce under ideal conditions
does not equal number of seeds produced
biotic potential represented by
carrying capacity
the # of individuals in each population that can live in a particular ecosystem is limited
as N becomes closer to K
crowding and competition result in
poorer growth
lower reproduction
birth rate decrease
death rate increase
decreased chance seedlings are in suitable sites
at N=K
population growth stops
death rate = birth rate
r- and K- selection
r-selection
disturbance usually produces r conditions
resources are plentiful for survivors (pioneers)
spread of predators and pathogens is slow
population density is low
biotic potential is limiting factor
mutations that increase r are selectively advantageous
K-selection
every possible suitable site for seed growth is filled
redwoods
Douglas firs
bristlecone pines
face intense competition from other plant species
The Structure of Ecosystems
physiognomic structure
physical size and shape of organisms and their distribution in relation to each other and to the physical environment
trees
shrubs
herbs
life forms
defined by C. Raunkiaer in 1934
therophytes
annual life span; survive stress as seeds
geophytes
buds are underground on rhizomes, bulbs, corms
hemicryptophites
buds are located at surface of soil, protected by leaf and stem bases: many grasses and rosette plants
chamaephytes
buds are located above ground, but low enough to not be exposed to strong winds: small shrubs
phanerophytes
buds are located high, on shoots at least 25 to 30 cm above ground: trees and large shrubs
temporal structure
changes that an ecosystem undergoes with time
could be 1 day or decades
species composition
the number and diversity of species that coexist in an ecosystem
depends on whether the climate is mild or stressful
soil quality
tolerance ranges (broad or narrow)
trophic levels
feeding levels
photosynthesis is dominant method
algae & cyanobacteria carry out about 1/3 of all photosynthesis worldwide
green vascular plants are most important
autotrophs
primary producers
herbivores
primary consumers (secondary producers)
carnivores
secondary consumers
top carnivores
tertiary consumers
wolves, lions, hyenas
decomposers
fungi & bacteria
break down remains of all types of organisms, even other decomposers
energy flow (carbon flow of ecosystems)
as plants are eaten their energy and carbon compounds move to the herbivore trophic level, the the carnivore trophic levels, and finally to the decomposers
