Transcript Ecology 2011 power point second half

Ecology 2011 power point
second half
Population density is the number of individuals that live in a defined area.
• Population density is a measurement of the number of
individuals living in a defined space.
• Scientists can calculate population density.
Geographic dispersion of a population shows how
individuals in a population are spaced.
• Population dispersion
refers to how a
population is spread in an
area.
Clumped
dispersion
Uniform
dispersion
Random
dispersion
• There are three types of dispersion.
– clumped
• There are three types of dispersion.
– uniform
• There are three types of dispersion.
– random
Survivorship curves
– 1. low level of infant
mortality and an older
population
– common to humans
– 2. survivorship rate is
equal at all stages of life
– 3. very high birth rate,
very high infant
mortality rate
Survivorship in a developing country.
Survivorship of a developed country.
Changes in a population’s size are determined by immigration, births,
emigration, and deaths.
• The size of a population is
always changing.
• Four factors affect the size
of a population.
– Immigration, moving in
– births
– Emigration, moving out
– deaths
Population growth is based on available resources.
• Exponential growth is a rapid population increase due to
an abundance of resources.
• Logistic growth is due to a population facing
limited resources.
• Carrying capacity is the maximum number of
individuals in a population that the environment
can support.
• A population crash is a dramatic decline in the size of a
population over a short period of time.
Ecological factors limit population growth.
• A limiting factor is something that keeps the size of a population
down.
• Density-dependent limiting factors are affected by the number of
individuals in a given area.
• Density-dependent limiting factors are affected
by the number of individuals in a given area.
– parasitism
and disease
– predation
– competition
• Density-independent limiting factors limit a
population’s growth regardless of the density.
– unusual weather
– natural disasters
– human activities
Succession occurs following a disturbance in an ecosystem.
• Succession regenerates or creates a community after a
disturbance.
– a sequence of biotic changes
– damaged communities are regenerated
– new communities arise in previously uninhabited areas
• There are two types of succession.
– primary succession — establishment and development of an
ecosystem in an area that was previously uninhabited
– started by pioneer species
• There are two types of succession.
– secondary succession — reestablishment of a damaged
ecosystem where the soil was left intact
– started by remaining species
The biosphere is the portion of Earth that is inhabited by life.
• The biosphere includes all ecosystems.
– one of Earth’s systems
– includes the biota, all the living things in the biosphere
Climate is the prevailing weather of a region.
• Climate is the long-term
pattern of weather conditions.
– average temperature
– precipitation
– relative humidity
• A microclimate is the climate of a small
specific place within a larger area.
• Mountains have an effect on climate.
– Precipitation occurs on the side of the mountain facing
the wind.
– On the downwind side, drier and cooler air produce a
rain shadow.
– A rain shadow is an area of decreased precipitation.
western slope
eastern slope
Earth has three main climate zones.
• The three main zones are the polar, tropical, and temperate climates.
– polar climate: the far northern
and southern regions of
Earth
– temperate zone: the
wide area in between
the polar and tropical zones
– tropical zone: surrounds
the equator
The angle of the sun’s rays
create these climate zones.
• Key factors influence an area’s climate.
– temperature
– sunlight
– Water and wind movement
– landmasses
• Earth’s tilt on its axis plays a role in seasonal change.
• Solar heating causes movements in both water and air.
– wind
– ocean currents
• Earth’s rotation also has effects on the winds and currents
Freshwater ecosystems include moving and standing water.
• A watershed is a region of land that drains into a body of
water.
• Ecosystems may be different along a river’s course
Fresh Water Zones
• Freshwater bodies are divided into three zones.
– littoral zone
– limnetic zone
– benthic zone
• All lakes “turn over” periodically.
– Turn over happens due to changes in density.
– In both autumn and spring, surface water flows downward
and bottom water flows upward.
– The upwelling brings up nutrients.
Salt Water (Marine) Zones
• Marine bodies have two
main zones.
– Coastal
•
•
•
•
High/Low Tide Line
Estuaries
Coral Reefs
Ends with continental
shelf.
Salt Water (Marine) Zones
• Marine bodies have two
main zones.
– Open Sea
•
•
•
•
Pelagic
Bathyal
Abyssal
Benthic
Earth’s human population continues to grow.
• Earth’s human carrying capacity is unknown.
• Technology has helped to increase Earth’s carrying capacity.
– gas-powered farm equipment
– medical advancements
The growing human population exerts pressure on Earth’s natural resources.
• Nonrenewable resources are used faster than they form.
– coal
– oil
• Renewable resources cannot be used up or can replenish
themselves over time.
– wind
– water
– sunlight
• Growing use of
nonrenewable
resources may lead
to a crisis.
• Resources must be
properly managed.
• An ecological footprint is the amount of land needed to support
a person.
• The land must produce and maintain enough
– food and water
– shelter
– energy
– waste
• Several factors affect the size of the ecological footprint.
– amount and efficiency of resource use
– amount and toxicity of waste produced