Chapter 30- Ecosystems and Environment

BIG IDEA: All organisms interact with living and nonliving things in

their environments

30.1 Organisms and their Environments

Ecology is the study of how organisms interact w/ their environments.

Population= a group of individuals in a single species living in a specific area

Community= all of the organisms w/in a specific area

Ecosystem= biotic (living) and abiotic (nonliving) organisms w/in a given area

1. An ecologist studies how hyenas and cheetahs compete for food, Is this a study at the population, community, or ecosystem level?

2. An ecologist is interested in counting how many mountain lions live in a certain park. Is this a study at the population, community, or ecosystem level?

Community, 2 different species being compared

Population, looking at 1 species, in a specific area

30.2 Species interactions in Ecological Communities

Food chains/webs- show who eats whom

Bottom= producers, species that make their own food (usually plants)

Primary consumers eat the producers

(Top)Secondary consumers eat the primary consumers (carnivores)

Decomposers consumer dead organic matter

Other species interactions:

Competition occurs any time 2 species in a community compete for the same resource, and there is a limited supply of resource-Competition can cause evolution

Niche is the total set of biotic and abiotic resources w/in a community (sunlight, water, food, space)

Symbiosis: individuals of 2 species that live in close proximity

1.Parasitism: Good for 1 species, harmful to the other (+/-)

2.Commensalism: Good for 1 species, no effect on the other (+/0)

3.Mutualism: Both species benefit (+/+)

Illinois invasive species

Invasive species: a species that has moved from it’s original home to a new area, causing lots of damage

Compete w/ native species for resources. Decrease natural diversity, increases cost of food an lumber production

Ex’s: Bush honeysuckle, Garlic-mustard, Asian carp

30.3 Energy Flow in EcosystemsBiomass is the amount of organic matter in an ecosystem

-Only ~10% of energy at one level of a food chain gets passed to the next level of the food chain.

Ex: producer= 10,000 kg of biomass (trees/grass), there would be 1000kg of primary consumers (like zebras), and 100kg of secondary consumers (lions)

The other 90% of energy?

Not every organism on one level is eaten, energy lost in maintenance, growth, and feces

When energy is converted from one form to another some energy is converted into heat

30.4 Kinds of ecosystemsThere are 8 major types of ecosystems (biomes)

-The type of biome found in a certain place depends mainly on climate (determines what plants/animals will thrive

1. Tropical forests: near equator, warm, large biodiversity, lots of rain, poor soil. Destroyed for timber/agriculture

2. Temperate forests: areas w/ 4 seasons, leaves change color and fall. Fertile soil (chopped down for farming)

3. Coniferous forests: Long, cold winters, dry, ground covered by pine needles. Threatened by logging.

4. Tundra: Extreme cold, permafrost (permanently frozen soil) above topsoil, low biodiversity

5. Savanna: Tropical grasslands, long dry season, animals prevent overgrowth

6. Temperate grasslands: very good soil, 4 seasons, don’t become forests b/c seasonal drought, fire, and grazing

7. Chaparral: Mild, rainy winters, hot dry summers. Drought, fire

8. Desert: Extremely dry (can be hot OR cold-Antarctica). Organisms have adaptations to survive extreme dry conditions

Aquatic ecosystemsFreshwater: Still water of lakes/ponds, and flowing water of rivers, streams. Have adaptations depending on environment

Saltwater: Many different species, at the surface, bottom, and in-between of ocean. Photic zone=closer to surface. Aphotic=bottom, no sunlight

Plankton- float in water, and go wherever current takes them (Ex: Microscopic organisms)

Vs.

Nekton- organisms that swim through the water (Ex: fish, whales, sea turtle)

Materials Cycling in EcosystemsGeochemical cycles move different substances from the biotic to abiotic world

Water- evaporates from water source condenses in clouds precipitates to land, runs off back ground water

Carbon- Found in atmosphere plants/other organisms back to abiotic world from cellular respiration

Nitrogen: bacteria convert atmospheric N2 can be used by living organisms

30.5 Change in an EcosystemEcological succession describes how the community of species living in an ecosystem changes over time

o Primary succession: colonization of bare land with no soil

oSecondary succession: when existing life in a habitat is destroyed, but soil remains.

Succession ends when stable population formsAll ecosystems experience change, smaller disturbances are more frequent

30.6 Population Studies4 Factors determine population size:

1.Birth rate 2. Death rate3. Immigration rate 4. Emigration rate

Exponential growth occurs when the population grows @ a fixed rate for a certain amount of time

-Populations that undergo exponential growth usually cycle w/ growth to crashing (resources run out!)

Logistic growth shows a slow climbing population as it approaches carrying capacity (max # a habitat can support). Stable populations

30.7 Human Population GrowthCurrent population: ~7.2 billion people

Growth was exponential in recent decades, but is now slowing down

We learn how population is growing from age structure