4-2 What Shapes an Ecosystem?• Habitat is shaped by: (like an address)• Biotic factors – the ecological

community. Ex. birds, trees, mushrooms, and

bacteria.• Abiotic factors- the climate of an area. Ex. temperature, precipitation, and

humidity.

Niche• The physical and biological conditions in

which an organism lives and the way in which an organism uses those conditions.

• Temperature it survives in• Type of food it eats• What eats it• How it obtains food• How it reproduces

Ex. of Niche

Bull Frog(amphibians) • In or near ponds, lakes, or slow moving

stream• Eats; insects, spiders, worms, small fish,

and mice.• In winter, they burrow in the mud and

hibernate.• Reproduction- Female bullfrogs lay eggs

in water during warmer months.

The Niche

Competitive Exclusion Principle- No two species can occupy the same niche in the same habitat. They can occupy niches that are similar.

Ex. Bay Breasted Warbler Cape May Warbler Yellow-Rumped WarblerThey avoid direct competition

Community Interactions• 1. Competition – Will result when two

of the same species or different species attempt to use the same resources (food,water, light, nutrients, or space) in the same place at the same time.

• Ex. Oak and Hickory trees grow tall and leaves are broad. They block out the sunlight for shorter trees.

Competition

• Competitive Exclusion Principle- Competitions results in a winner and a loser- with the loser failing to survive.

Predation

One organism captures and feeds on another organism.

The organism that does the killing is the predator.

The food organism is the prey

2. Symbiosis-Any relationship where two organisms live

closely together.1. Mutualism – Both benefit. Ex. flowers and

insects2. Commensalism- One benefit and the

other is not helped or harmed. ex. barnacles attach to whale skin.

3. Parasitism- One organism lives in or on another and harms it. The one being harmed is called the host. Ex. fleas, ticks, lice, tapeworms.

Ecological Succession

• Series of predictable change that occur in a community over time.

• Primary succession- Occurs where no soil exists.

Ex. As volcanic islands form.Ex. When glaciers melt exposing

bare rock.

Pioneer Species

• Stage one primary succession.• Ex. Lichen (fungus and alga) they

break down rock. When they die the material become soil. Now other plant and organisms begin to arrive.

• Ex. Mosses.

Stage 2 accumulation stage

Annuals dominate soil.Nutrient pore soil. Ex. Plants like legumes have

relationship with rhizobia bacteria(nitrogen fixing)

Decomposition of bacteria and fungi and waste of small animals all add to soil.

Soil vs. dirt• Soil is alive• Dirt is minerals

Stage 3 perennial herb stage

• Soft tissue perennials dominate. They may take several years to reproduce.

• They will out compete annuals b/c they can reproduce sexually. Annual will be present but perennials dominate.

• They modify the soil for the next stage.

4. shrub stage – Woody multi stemmed plants less than 10 feet.

• Modify soil for the next stage….5. Shade intolerant trees- Require and or

tolerate high sunlight. Pine tree.Fire adapted may never reach stage 6.6. Shade tolerate- Trees can grow and thrive

in shade. Ex. Oak and hickory.

• Stage 6. Canopy forest- see picture on board.

• Shade tolerate out compete shade intolerant.

• If you make it to stage 6 you don’t always stay there. Ex. Tree falls from wind. Insect damage. Fire comes in.

• When there is a disturbance you will see a mix of stages.

• Stage 6 used to be called climax forest. • Ecologist are getting away from that term.Why do you think?Once you reach stage 6 you may call it Oak

& Hickory forest b/c they dominate. But there is always patches of disturbance.

Secondary seccesion

• Same as primary except no stage 1 or 2..

Ex. An old abandoned farm.

Old Growth vs. Immature Community

1. OG reaches stage 6.2. OG is moist compared to IC.3. OG highly organized many layers.Canopy, sub canopy, shrub layer.4. OG differs in species diversity may have

high or low.

Succession of Marine Environment

1. Dark ocean floor, a whale falls to the bottom and dies. Scavengers and decomposers come to the scene to feed on the whale. Ex. Sharks,, hag fish, bacteria, and amphipods.

2. Within a year most whale tissue is gone; crabs, snails, small fish, use site for shelter. Bottom of ocean is enriched, many worm species.

• 3. Heterotrophic bacteria move in, feed off of oils inside decomposing bone.

• As they feed they release chemicals that attract chemosynthetic bacteria.

• Chemosynthetic bacteria are a food source for mussels, limpets, snails, worms, crabs, clams, etc….

BiomesTropical Rain ForestHot and wet all

yearBroad leaf

evergreenClimbing plantsNutrient poor soil

Tropical Dry ForestWarmWet & dry seasonsDeciduous

Biomes

Tropical SavannaWarmSeasonal rainfallFrequent fires

Desert• Less than 25 cm

a year.• Extreme temp.

changes• Rich in minerals

poor organic• Extensive root

system

Temperate Grasslands• Mix of grasses• Fertile soil• Moderate temp.• Seasonal rain

Temperate woodland and shrubland

• AKA chaparral• Hot & dry

summers• Cool & moist

winters• Freq. fires

Boreal Forest aka. Taiga• Long cold winter• Short warm summer• Moderate rain• Needle leaf conifers• Nutrient poor soils• Wolves, moose, spruce

Tundra• Permafrost• Short cool summer• Low rain• Mosses, lichen, short grasses

Mountain Ranges• As you go up it

gets colder• More rainfall on

one side of the mountain

Polar• Mosses, lichen,

mites, polar bears, penguin, rates

Sec. 5-1

• Population density-Number of individuals per unit area.

• Population growth- Births, deaths, immigration, and emigration.

• Exponential growth- When individuals grow at a constant rate. see fig.5-3

• Logistic growth-when population growth slows or stops following a period of exponential growth.

• Carrying capacity is the largest number of individuals an environment can support.

• Do Now: If an entire lynx population disappears, What is likely to happen to the hare population on which it preys?

• Objective :Explain why population rates differ from country to country.

Sec 5-3• Demography- Study of human

population• Demographic transitions- a dramatic

change in birth and death rates.see fig.5-12

• Age structure diagrams- population profile by age. See figure 5-13

Future population growth• Some scientists believe that if the

population growth rate does not slow down, humans will outgrow our food and other supplies. And bust will occur.

• Other scientist think that technology will handle any problems with supplies and ecosystem recovery and the human population will remain stable.

• What’s you opinion?