Download TERRESTRIAL BIOMES Deserts Grasslands Tundra

Ecology and People (BIOL 120)
Lecture 4: Biomes; Population and
Community Ecology
Announcements
Today’s Outline
Biome Basics!
Population Ecology
Population Dynamics
Human Impacts
TERRESTRIAL BIOMES
!Biomes - Areas sharing similar climate,
topographic and soil conditions, and
roughly comparable communities.
"Temperature and precipitation are among the
most important determinants in biome
distribution.
!Most terrestrial biomes are identified by the dominant
plants of their communities.
Grasslands
! Communities of grasses and seasonal
herbaceous flowering plants.
! Large daily and seasonal temperature
fluctuations.
! Frequent grass fires.
! Historic grazing by roaming herds of animals.
Realm
of
Ecology!
Biomes
Populations
Deserts
! Characterized by low moisture levels and
precipitation.
! Wide daily and seasonal temperature
fluctuations.
! Soils are easily disturbed by human activities,
and slow to recover.
! Plants exhibit water conservation
characteristics.
Tundra
! Treeless
! Very short growing season, with cold harsh
winters.
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Conifer Forests
!Cone-Bearing
!Plants reduce water loss by evolving thin,
needle-like evergreen leaves with thick
waxy coating.
Broad-Leaved Deciduous Forest
!Temperate regions support lush summer
plant growth when water is plentiful.
"Deciduous leaves an adaptation to freezing
temperatures.
Conifer Forests
!Boreal Forest - Northern Conifer Forest
"Broad band of mixed coniferous and deciduous
trees between 45° and 60° N latitude.
"Moist and cool climate with abundant streams
and wetlands.
Tropical Moist Forests
! Humid tropical regions support one of most
complex and biologically rich biomes.
! Ample rainfall and uniform temperatures.
! Tropical Rainforests - More than 200 cm annual
rainfall with warm-hot temperatures year-round.
" 90% nutrients tied up in living organisms.
" Rapid decomposition and nutrient cycling.
" Thin soil cannot support continued cropping, and cannot
resist erosion.
Population ecology
Population Dynamics and Carrying Capacity
**the basics**
# What is a population?
# The two basic characteristics of
a population
# Rate of growth
# Birth rate minus death rate
# Final size of the population -carrying capacity
$ Population dynamics
$ Biotic potential
$ Exponential vs. Logistic Growth
$ Carrying capacity
$ Population Density
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Exponential and Logistic Growth
The Role of Predation in Controlling Population Size
$ Predator-prey cycles
$ Top-down control
$ Bottom-up control
Survivorship Curves
Population ecology
**Human Impacts**
!Birth rate, death rate, carrying capacity
!Utilization rate (= part of death rate)
Human Impacts on Populations and
communities
$ Habitat degradation and fragmentation
$ Ecosystem simplification
$ Predator elimination
$ Introduction of non-native species
$ Over-harvesting renewable resources
$ Interference with ecological systems
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