Chapter 4: Ecosystems and Communities

Chapter 4: Ecosystems and Communities

Vocabulary• Weather• Climate• Greenhouse• Niche • Habitat• Symbiosis• Succession• Biomes

Key Concepts• What factors

determine climate?• How does competition

shape communities?• How do communities

change over time?• What biotic and

abiotic factors characterize biomes?

4.1 Climate• Both weather and climate involve variation in environmental changes such as temperature and precipitation

So what’s the difference??• Weather includes day to day changes and conditions

•Climate refers to averages over long periods of time

•Climate tends not to be uniform within a region and microclimates can be created•Northern Hemisphere, the south side facing trees receive more sunlight creating warmer, drier area

Factors that Affect Climate

1) Greenhouse Effect – gases (CO2, methane, water vapor) in atmosphere allow light energy in but trap heat

• we need this to keep Earth at livable temperature

• If concentration of greenhouse gas increases, temperature rises

• If concentration decreases, temperatures lower

Factors that Affect Climate

2) Latitude• Sun hits the earth more directly at the equator than at the poles

- Causes more tropical environment at equator

•Due to the curvature of the sun, the energy is spread over a much larger area

Factors that Affect Climate

3) Heat Transport in Biosphere

•Unequal distribution of heatcreates currents and wind

- Transports moisture and heat- Warm air less dense and rises,

cold air more dense and sinks

Winds

• Up and down movements of the air masses create winds

Currents

• Similar heating and cooling patterns also create ocean currents

4.2 Niches and Community Interactions

• Organisms occupy different places due to varying conditions that allow them to grow and reproduce• Varying conditions help define where organisms can live

• 2 factors that shape where and how organisms live are biotic and abiotic factors

• Any of these biotic or abiotic factors that restricts the number of organisms, their distribution, existence, or ability to reproduce is called a limiting factor

• An example of limiting factor is the timberline– Elevation, winds,

shallow soil, etc..• Factors that limit one

population may have an indirect affect on other populations within that community– Lack of water,

decreases seed production, affects mice that are dependent on those seeds

• Range of Tolerance– The ability of an

organism to withstand fluctuations in biotic and abiotic factors

– Catfish can withstand warmer water than trout or bass

Organisms in Ecosystems• Habitat

(address) = area where an organism lives– Includes biotic

and abiotic factors

Organisms in Ecosystems• Niche (job)=full range of physical and

biological conditions in which the organism lives and the way the organism uses those conditions– Ex: place in the food web, range of

temperatures the organism needs to survive, food the organism eats

• If two species try to occupy the same niche, it creates competition– Result: one species will not survive

extinction

• No two species can share the same niche in the same habitat

• Different species can occupy different niches that are very similar

Interactions• Organisms in an ecosystem interact constantly

– Shapes the ecosystem• Ways of interaction

– Competition– Predation– Symbiosis

• Mutualism• Commensalism• Parasitism

Resource=necessity of life• Competition= when

organism try to use a resource at the same place/time– Two lizards want to eat

the same type of insect

• Predation= one organism captures and feed on another– Bald Eagle (predator)

eating fish (prey)

• Keystone species = change in a single species within a population can cause dramatic changes in community– Examples: wolves of Yellowstone, sea otters,

black-footed ferrets

Symbiosis= two species live closely

Mutualism= both species benefit from the relationship

Flowers and insects

Commensalism= one species benefits, the other is not helped or harmed

Whales and barnacles

Parasitism= One organism lives on/inside the other and harms it

Tapeworm , trichinella

4.3 Succession• Ecosystems change—human intervention, natural

disaster

• Series of predictable changes that occur in a community over time = ecological succession

• Primary succession= occurs on surfaces where there is no soil– Volcanoes build up an island– Pioneer species= 1st organisms to populate

• Once a community becomes stable, mature, and little change in species, it is known as a climax community

• Secondary succession = some kind of change happens, but soil remains– Fire– Land cleared/plowed

• Change in species is also slow, as in primary succession, but…

– Seeds in the soil from previous vegetation takes over

4.4 Biomes• Biome = large group of ecosystems that

share similar climax community

• Biomes are located on land (terrestrial) and in water (aquatic)

• Aquatic Biomes1. Marine

- Refers to salt waters (oceans, seas)- Contains the largest amount of biomass (living

material)- Photic zone: shallow, sunlit

- Rocky shores, sandy beaches, mudflats

- Aphotic Zone: deeper, no sun light

• Areas where salt water and fresh water meet are called estuaries– Salinity (amount of salt) ranges between very

salty to fresh water– Changes with the tides

• Tides– Rise and fall of ocean tides are caused by the

sun and moons gravitational pull.– Intertidal zone: portion of shoreline that is

between high and low tides• Size varies depending on slope of land and height

of tide

2. Freshwater biomes- streams, lakes, ponds- limiting factors: light and temperature

Terrestrial Biomes

• Two abiotic factors that affect terrestrial biomes are temperature and precipitation

• 6 different types of biomes– Tundra, taiga, grassland, deciduous forests,

rain forests, and deserts