Ecology—the scientific study of interactions between different organisms and between organisms and their environment or surroundings

Biotic—living factors that influence an ecosystem

Abiotic—non-living factors that influence an ecosystem

Producers

A. Sunlight is the main energy source for life on earth

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2. Also called autotrophs

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C. Use light or chemical

energy to make food

1. Plants

2. plant-like protists (algae)

3. Bacteria

D. Photosynthesis—use light energy to convert carbon dioxide and water into oxygen and carbohydrates

(Remember: 6CO₂ + 6H₂O 6O₂ + C₆H₁₂O₆)

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E. Chemosynthesis—performed by bacteria, use chemical energy to produce carbohydrates

Consumers

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1. Organisms that rely on other organisms for their energy and food supply

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B. Also called heterotrophs

Herbivores—obtain energy by

eating only plants

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Carnivores—eat only animals

Omnivores—eat both plants and animals

Decomposers—breaks down dead organic matter

Feeding Interactions

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A. Energy flows through an ecosystem in one direction—from the sun or inorganic compounds to autotrophs (producers) and then to heterotrophs (consumers)

2. Food Chain—series of steps in which organisms transfer energy by eating and being eaten

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• Arrows go in the direction of how energy is transferred

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• Start with producer and end with top consumer

or carnivore

C. Food Web—network of food chains within an ecosystem

Which of the organisms above is the producer?

Which of the organisms above is the top consumer?

Grass

Hawks

4. Trophic Levels—each step in a food chain or food web

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1. Level 1—Producers (autotrophs)

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2. Level 2—Primary Consumers (herbivores)

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3. Level 3—Secondary Consumers

(carnivores or omnivores)

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4. Level 4—Tertiary Consumers

(carnivore—usually top carnivore)

Food Webs

4. Ecological Pyramids

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A. Diagram that shows the relative amount of energy or organisms contained within each trophic level of a food chain or web

2. Energy Pyramid shows relative amount of energy available at each trophic level

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1. Organisms in a trophic level use the available energy for life processes (such as growth, photosynthesis, cellular respiration, metabolism, etc.)and release some energy as heat

Remember: Every chemical process that happens in your body releases heat as a byproduct (ex: burning calories).

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2. Rule of 10—only about 10% of the available energy within a trophic level is transferred to the next higher trophic level

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C. Biomass Pyramid—represents the amount of living organic matter at each trophic level

Energy Pyramid

Biomass Pyramid

Represents amount of energy available at each level as well as amount of living tissue—both decrease with each increasing trophic level

Energy and Biomass Pyramid (together)

Heavy metals

Ex: mercury

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Pesticides

Ex: DDT (dichlorodiphenyltrichloroethane)

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Organochlorides:

Ex: PCBs

V. Ecological Interactions between organisms

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1. Competition—when two organisms of the same or different species attempt to use an ecological resource in the same place at the same time.

Ex: food, water, shelter

Monkeys compete with each other and other animals for food.

Rams compete with each other for mates.

Until Americans introduced gray squirrels into parts of England in the early 20th century, red squirrels had been the only species of squirrel in the country. The gray squirrels were larger and bred faster and successfully competed for resources. Within a couple years of overlap in an area, the red squirrels disappeared.

B. Niche—the ecological niche involves both the place where an organism lives and the roles that an organism has in its habitat.

Example: The ecological niche of a sunflower growing in the backyard includes absorbing light, water and nutrients (for photosynthesis), providing shelter and food for other organisms (e.g. bees, ants, etc.), and giving off oxygen into the atmosphere.

The ecological niche of an organism depends not only on where it lives but also on what it does. By analogy, it may be said that the habitat is the organism’s “address”, and the niche is its “profession”, biologically speaking.

Worm’s Niche

“Address”—Soil, Ground, etc.

“Profession”– Mix-up soil

C. Predation—one organism captures and feeds on another organism

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1. Predator—one that does the killing

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2. Prey—one that is the food

D. Symbiosis—any relationship in which two species live closely together

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1. Mutualism—both species benefit (WIN-WIN)

a. Ex: insects and flowers

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Can you think of any other examples that we’ve talked about in class?

2. Commensalism—one member of the association benefits and the other is neither helped nor harmed.

(WIN-0)

Example: barnacles on a whale

Commensalism

The Remora fish attaches to the shark and gets a free ride.

Birds build nests in trees.

3. Parasitism—one organisms lives on or inside another organism (host) and harms it.

The parasite obtains all or part of its nutritional needs from the host. (WIN-LOSE)

Example: fleas on a dog

Parasitism

Wasp eggs on back of caterpillar.

Mosquito biting a human.

Sea lampreys feed on fluids of other fish.

Mutualism, Commensalism or Parasitism??

BIOMES� AND�ECOSYSTEMS

What is a biome?

• A biome is a group of land ecosystems with similar climates and organisms

There are 6 major land biomes and 2 major water ecosystems?

LAND (6): RAINFORESTS, DESERTS, GRASSLANDS, DECIDOUS FORESTS, BOREAL FORESTS, & TUNDRA

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WATER (2): FRESHWATER & MARINE ECOSYSTEMS

• An area’s biome is determined mostly by its climate (temperature and precipitation)

RAIN FORESTS

• There are 2 main types of rain forests: Temperate Rain Forests and Tropical Rain Forests.

TEMPERATE RAIN FORESTS

• “Temperate”= having moderate temperatures.
• Northwestern coast of U.S. is a temperate rain forest.
• Receives more than 300 cm of rain per year.
• Huge trees: Cedars, Redwoods, Douglas Firs.

TROPICAL RAIN FORESTS

• Found in regions close to the equator
• Warm and humid all year long.
• Lots of precipitation.
• Diverse plant growth.

• Trees in the rain forest form several layers…

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Canopy: A leafy roof formed by the tallest trees.

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Understory: A second layer of shorter trees and vines.

• Understory plants grow well in the shade formed by the canopy, but the forest floor is nearly dark and only a few plants live there.

DESERTS

• Desert = An area that receives less than 25 cm of rain per year.
• Some deserts receive NO precipitation at all during one year.
• Deserts often undergo large shifts in temperature during the course of a day.

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The scorching Namib desert in Africa cools rapidly after the sun goes down.

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The Gobi desert in central Asia is cooler and even experiences freezing temperatures in the winter.

• Organisms that live in the desert must be adapted to the lack of rain and extreme temperatures.

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• Saguaro Cactus: Stem expands to store water.
• Gila monster spends weeks in its cool, underground burrows.
• Many other organisms are only active at night when it is cooler.

GRASSLANDS

• Grassland (prairie)= An area that is populated mostly by grasses and other non-woody plants.
• Receive 25 to 75 cm of rain per year.
• Fires and droughts are common.

Savanna: Grassland that is located closer to the equator than prairies.

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• Savannas can receive as much as 120 cm of rain per year.
• In addition to grass, scattered shrubs and small trees can grow in the savanna.

• Grasslands are home to many of the largest animals on Earth.
• Examples:

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• Grazing by these large herbivores helps to maintain these grasslands.

DECIDUOUS FOREST

• Deciduous trees= Trees that shed their leaves and grow new ones each year (Oaks, Maples…)

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• Receive enough rain to support the growth of trees and other plants (at least 50 cm per year).
• Growing season is 5 to 6 months long.

BOREAL FOREST (taiga)

• Mostly contains coniferous trees (trees that produce their seeds in cones and have leaves shaped like needles). Ex. Fir, Spruce, Hemlock…
• Very cold winters (a lot of snow).
• Warm and rainy summers.

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TUNDRA

• Tundra = Extremely cold and dry biome.
• Usually receives NO more precipitation than a desert biome.
• Most soil is frozen all year long (permafrost)
• During summer, the top layer of soil thaws, but the rest remains frozen.

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PERMAFROST

• Because rainwater cannot soak into the permafrost, there are many shallow ponds and marshy areas of the tundra during the summer

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Tundra Plants and Animals

POLAR BEAR

WOLF

REINDEER

ARCTIC

FOX

ARCTIC HARE

Biogeochemical Cycles

Water

Nitrogen

Carbon Dioxide

Phosphorus

Sulfur

Biogeochemical Cycle :

• chemical elements are required by life from the living and nonliving parts of the environment.
• These elements cycle in either a gas cycle or a sedimentary cycle
• In a gas cycle elements move through the atmosphere.
• Main reservoirs are the atmosphere and the ocean.
• Sedimentary cycle elements move from land to water to sediment.

Carbon�Cycle

• What are the

2 main processes in the carbon cycle?

Carbon Cycle

• Carbon (C) enters the biosphere during photosynthesis:
• CO₂ + H₂O (carbon dioxide+ water)--->

C₆H₁₂O₆ + O₂ + H₂O(sugar+oxygen+water)

• Carbon is returned to the biosphere in cellular respiration:
• O₂ +H₂O + C₆H₁₂O₆ ---> CO₂ +H₂O + energy

Carbon Facts

• Every year there is a measurable difference in the concentration of atmospheric CO₂ with changes in the seasons.
• For example, in winter there is almost no photosynthesis ( higher CO₂ )
• During the growing season there is a measurable difference in the concentration of atmospheric CO₂ over parts of each day.

Nitrogen cycle

Nitrogen Facts

• Nitrogen (N) is an essential constituent of protein, DNA, RNA, and chlorophyll.
• Nitrogen is the most abundant gas in the atmosphere.
• Nitrogen must be fixed or converted into a usable form.

Oxygen Cycle (Photosynthesis)

Sources of Oxygen:

• Photosynthesis and respiration
• Photo disassociation of H₂O vapor
• CO₂ and O₂ circulates freely throughout the biosphere.
• Some CO₂ combines with Ca to form carbonates.
• O₂ combines with nitrogen compounds to form nitrates.
• O₂ combines with iron compounds to form ferric oxides.
• O₂ in the troposphere is reduced to O3 (ozone).
• Ground level O₃ (ozone) is a pollutant which damages lungs.

Phosphorus (P) Cycle

Phosphorus (P) Cycle

Component of DNA, RNA, ATP, proteins and enzymes

- Cycles in a sedimentary cycle

- A good example of how a mineral element becomes part of an organism.

- The source of Phosphorus (P) is rock.

- Phosphorus is released into the cycle through erosion or mining.

- Phosphorus is soluble in H2O as phosphate (PO4)

-Phosphorus is taken up by plant roots, then travels through food chains.

- It is returned to sediment

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Sulfur (s) Cycle

• Component of protein
• Cycles in both a gas and sedimentary cycle.
• The source of Sulfur is the lithosphere (earth's crust)
• Sulfur (S) enters the atmosphere as  hydrogen �sulfide (H2S) during fossil fuel combustion, volcanic �eruptions, gas exchange at ocean surfaces, and decomposition.
• SO₂ and water vapor makes H₂SO₄ ( a weak sulfuric acid), � which is then carried to Earth in rainfall.
• Sulfur in soluble form is taken up by plant roots and �incorporated into amino acids such as cysteine. It then travels through the food chain and is eventually released through decomposition. �  �

Summary

• The building blocks of life :Water ,Nitrogen, Carbon Dioxide, Phosphorus, Sulfur
• Continually cycle through Earth's systems, the atmosphere, hydrosphere, biosphere, and lithosphere, on time scales that range from a few days to millions of years.
• These cycles are called biogeochemical cycles, because they include a variety of biological, geological, and chemical processes.