CH 25:Populations and ecosystems
Plants in relationship to Their habitats
concepts
individuals of same species= population
populations together= community
populations are rarely stable #
Abiotic Components of the Habitat
climate is critically important to all organism
climate includes: temperature
climate=relative humidity and winds
plants that invade new soil=pioneers
zone of leaching=A horizon
zone of deposition= B horizon
parent rock and rock fragments= C horizon
at the equator, all days are 12 hours long
disturbances
Biotic Components of the habitats
mutalism
interaction that is beneficial to both organisms= mutualism
competitive exclusion
interrelationships between plants and organisms
commensal relationship
herbivores
between plants and fungi=pathogenic
orchid seeds are tiny and lack chlorophyll
ecosystem is extremely complex #
The Structure of Population
Graphic Distribution
limiting factor
water is important to many species #
biotic factor are critical
soil textures are important
no obvious pattern: random distribution
clumped distribution: space between plants
uniform distribution: evenly spaced
demography #
Age distribution: demography
generation time
biotic potential=number of offspring produced by an individual
carrying capacity
population growth is limited
germination decreases and death rate increases
large plant populations is ideal for insects
r- and k- Selection
r- selected species are usually small perennials
few defenses against predators
too short to compete for sunlight
red woods is an example of k- selected species
k-:face intense competition
The Structure of the Ecosystems
trees, shrubs, and herbs
changes an ecosystem undergoes= temporal structure
species composition
mild climates and rich soil=support species
Trophic levels= feeding levels
autotrophs are known as primary herbivores
secondary consumer
decomposers such as fungi
energy/carbon flow of ecosystem
pyramid energy
decomposers are important in the ecosyste