Chap 36 Ecosystems and Conservation Biology

36.1 Feeding Relationships

• Every organism requires energy to carry out life processes such as growing, moving, and reproducing.

• Producers:• Convert light energy from sunlight to chemical energy• Consumers:• Obtain chemical energy from consuming other

organisms• Decomposers:• Break down wastes and dead organisms

• How is energy passed between these organisms?

• Flower takes in sunlight• Grasshopper eats flower• Mouse eats grasshopper• Eagle eats mouse

• What is this an example of?• Food chain:• Pathway of food transfer from one trophic

level to another. • Trophic level:• Feeding level

Producers

• Always on the bottom of the food chain• Base for all food webs• If we had no producers, would anything live?• No!

Ex.

Consumers

• Herbivore:• Only eats plants

• Carnivore:• Only eats other organisms

• Omnivore:• Eats both plants and other consumers

Consumers• Primary consumers (1st level consumer)(2nd trophic

level)• Feeds directly on the producers

• Secondary consumers (2nd level consumer)(3rd trophic level)

• Consumer that eats primary consumers

• Tertiary consumers (3rd level consumer)(4th trophic level)

• Consumer that eats secondary consumers

• What can primary consumers only be?

• Herbivores• Omnivores• Carnivores

Decomposers

• At each trophic level, organisms produce waste and die.

• The waste and remains of dead organisms is called detritus.

• Often called scavengers.• Ex.• Earthworms, crayfish, vultures etc.

What is this?

Food Web

• Food web:• Pattern of feeding represented by

interconnected and branching food chains.

36.2 Energy Flows • Of the light energy that reaches plants what percentage is

used for photosynthesis?• 1%

• Biomass: • Organic material manufactured by plants

• Primary productivity:• The rate of which producers in an ecosystem build biomass.

• Primary productivity determines the maximum amount of energy available to all higher trophic levels.

Which biome has the most primary productivity?

• Desert

• Savanna

• Deciduous forest

• Rain forest

Rain forest

Ecological Pyramids

• As each consumer feeds, some energy is transferred from lower trophic levels to higher, but most energy in the preys organism’s biomass is lost.

Caterpillar eats a leaf

• 50% of the energy in the leaf passes as the caterpillars waste.

• The caterpillar uses 35% of the energy from the leaf for energy for itself.

• Only about 15% of the leafs stored energy is turned into biomass for the caterpillar.

Energy Pyramid

• Energy pyramid:Shows the energy loss from one trophic level to another.

• An average of 10% of energy is converted to biomass in the next trophic level.

• 90% is lost as heat.

Energy Pyramid

Pyramid of numbers

• Pyramid of numbers:• Shows the number of individual organisms in

each trophic level.• Organized like energy pyramids.

36.3 Chemical Cycles

• General steps• 1. Producers incorporate chemicals from the

nonliving environment into organic compounds.

• 2. Consumers feed on producers, either using them as energy or releasing them as waste.

• 3. Organisms die and decomposers break them down and return to soil.

Carbon and Oxygen Cycle

• 1. Volcanoes, organisms, and cellular respiration produces carbon dioxide.

• 2. Plants uses the carbon dioxide and produce oxygen.

Nitrogen Cycle

• 1. Bacteria convert nitrogen gas to ammonia through a process called nitrogen fixation.

• 2. Other bacteria take the ammonia and produce ammonium though a process called nitrification.

• 3. Plants absorb the ammonium and can be consumed by other organisms.

• Organisms die and cycle repeats.

Water Cycle

• Plants transpire, and water evaporates from bodies of water.

• Condensation releases by precipitation back to the Earth.

• Run off and groundwater go into bodies of water.

36.4 Human Activities

• Human activities can affect chemical cycling by moving nutrients from one place to another.

• Humans eat vegetables from different parts of the country.

• Human waste might be carried to the ocean in sewage.

Carbon Cycle Impacts

• Burning of wood and fossil fuels is one source of carbon dioxide.

• As nations industrialize and use wood, carbon levels increase.

• What organisms use carbon dioxide to make oxygen?

• Plants

• What is happening to trees and forests?• Deforestation:• Clearing of forests for agriculture.

• All the carbon dioxide builds up in the Earth’s atmosphere, trapping heat.

• Greenhouse effect:• Natural process that stops all sun’s heat from

escaping rapidly back to space.

• This is leading to global warming.• Global warming:• Rise in Earth’s average temperature.

Other effects of Pollution

• Who here eats fish?

• Why do some people not eat fish anymore?

• High amounts of mercury.

Bio Magnification

• If a small fish has mercury in its system and gets eaten by a bigger fish… the bigger fish now has a higher amount of mercury in its system.

• The amount of mercury increases as the small fish gets consumed and moves up a food chain.

Ozone Layer

• Pollution in the atmosphere affects a gas called ozone (O3).

• Ozone layer absorbs ultraviolet radiation, and shields organisms.

• Ozone layer is thinning because of chlorofluorocarbons.

• Aerosol cans, refrigerator units.

36.5 Conservation Biology

• Which biome has the most biodiversity?

• Tropical Rainforest!

• What is happening to our tropical rainforests?• Deforestation

Threats to Biodiversity

• 11% of the 9,040 bird species are endangered.

• 680 plant species of the 20,000 plant species in the US are endangered.

• Biologist estimate that 20% of the freshwater fish in the world have either become extinct or threatened.

Habitat Destruction

• The human population is increasing so we need more land for agriculture, roads etc.

Introduced Species

• Introduced species: Non-native species• House sparrows, starlings came over from

Europe. • Compete with native birds for nesting spots.• Share resources.

Overexploitation

• Overexploitation:• Practice of harvesting or hunting to a degree

that the number of remaining individuals may not be able to sustain the population.

• Ex. Rhino-Use horns for trade and medicine.• Scallop- Overfished for food.

Conversation Biology

• How to we maintain biodiversity and ecosystems?

• Balance demands for resources• Establish areas than humans can not interfere

with. (buffer zones) • Develop natural resources.