Ecology

Chapter 13: Principles of Ecology

Ecology is the study of the interactions among living things, and between living things and their surroundings. Ecologists group living things into an organizational system.

An organism is an individual living thing.

A population is a group of the same species that lives in one area.

A community is a group of different species that live together in one area.

An ecosystem includes all of the organisms as well as the climate, soil, water, rocks and other nonliving things in a given area.

A biome is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there.

An ecosystem includes both biotic and abiotic factors. Biotic factors are living things. –plants –animals –fungi –Bacteria Mangrove trees Mangrove crabs Bracket fungi on mangrove tree

Abiotic factors are nonliving things. –moisture –temperature –wind –sunlight –Soil The balance of these determines which living things can survive in a given environment.

Biodiversity is the assortment, or variety, of living things in an ecosystem. Rain forests have more biodiversity than other locations in the world (50% of all species)

Life in an ecosystem requires energy. Producers provide energy for other organisms in an ecosystem. Producers get their energy from non-living resources (the sun, carbon dioxide & water) meaning they make their own food through photosynthesis. They are also called autotrophs. All ecosystems depend on producers, because they provide the basis for the ecosystems energy.

Consumers are organisms that get their energy by eating other living or once-living resources. Consumers are also called heterotrophs because they feed off of different things.

Consumers are not all alike: –Herbivores eat only plants. Cows, Horses. –Carnivores eat only animals. Tigers, Sharks. –Omnivores eat both plants and animals. Humans, Rats. –Detritivores (aka scavengers) eat dead organic matter. Millipede, Hyena. –Decomposers are detritivores that break down organic matter into simpler compounds. Fungus, Bacteria. carnivore decomposer detritivore

Almost all producers obtain energy from sunlight. Photosynthesis in most producers uses sunlight as an energy source. Chemosynthesis in prokaryote producers uses chemicals as an energy source.

A food chain is a model that shows a sequence of feeding relationships & shows the flow of energy in an ecosystem. A food chain links species by their feeding relationships. A food chain follows the connection between one producer and a single chain of consumers within an ecosystem. DESERT COTTONTAILGRAMA GRASSHARRIS’S HAWK ProducerConsumer

Arrows in the chain always show the direction of energy flow.

Each organism may have multiple feeding relationships in an ecosystem, which is shown by a Food Web

Important Members of Food Webs: A keystone species is a species that has an unusually large effect on its ecosystem. Keystone species form and maintain a complex web of life. creation of wetland ecosystem increased waterfowl Population increased fish population nesting sites for birds keystone species

The beaver is a keystone species, because it creates wetlands by creating dams. It causes: Greater number & wider variety of fish More fish eating birds: herons & kingfishers More insects and insect-eating birds on the shore Waterfowl nest on the shore Without the beaver, there would be a decrease in all these organisms.

Specialists are consumers that primarily eat one specific organism or a very small number of organisms. They are very sensitive to changes in the availability of prey. Generalists are consumers that have a varying diet. A gray wolf feeds on elk, moose, deer, beavers & even mice. Koalas are specialists because they eat only eucalyptus leaves.

Trophic levels are the nourishment levels in a food chain. –Primary consumers are herbivores that eat producers. (2 nd Trophic Level) –Secondary consumers are carnivores that eat herbivores. (3 rd Trophic Level) –Tertiary consumers are carnivores that eat secondary consumers. (4 th Trophic Level) –Omnivores, such as humans that eat both plants and animals, may be listed at different trophic levels in different food chains. (2 nd, 3 rd, or 4 th Trophic Level) Primary ConsumerSecondary Consumer Tertiary Consumer 2 nd Trophic Level 3 rd Trophic Level 4 th Trophic Level

Energy Pyramids Energy pyramids compare energy used by producers and other organisms on trophic levels. Between each tier of an energy pyramid, up to 90 percent of the energy is lost into the atmosphere as heat. Only 10 percent of the energy at each tier is transferred from one trophic level to the next.

A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem. tertiary consumers secondary consumers primary consumers producers ,000 5,000,000 producers A vast number of producers are required to support even a few top level consumers.

Water cycles through the environment. The hydrologic, or water, cycle is the circular pathway of water on Earth. Organisms all have bodies made mostly of water. precipitation condensation transpiration evaporation water storage in ocean surface runoff lake groundwater seepage

fossil fuels photosynthesis carbon dioxide dissolved in water decomposition of organisms respiration carbon dioxide in air photosynthesis combustion respiration Carbon is the building block of life. –The carbon cycle moves carbon from the atmosphere, through the food web, and returns to the atmosphere. –Carbon is emitted by the burning of fossil fuels. –Some carbon is stored for long periods of time in areas called carbon sinks.

nitrogen in atmosphere animals denitrifying bacteria nitrifying bacteria nitrifying bacteria ammonium ammonification decomposers plant nitrogen-fixing bacteria in soil nitrogen-fixing bacteria in roots nitrates nitrites The nitrogen cycle mostly takes place underground. –Some bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixation. –Some nitrogen-fixing bacteria live in nodules on the roots of plants; others live freely in the soil.

–Ammonia released into the soil is transformed into ammonium. nitrogen in atmosphere animals denitrifying bacteria nitrifying bacteria nitrifying bacteria ammonium ammonification decomposers plant nitrogen-fixing bacteria in soil nitrogen-fixing bacteria in roots nitrates nitrites –Nitrifying bacteria change the ammonium into nitrate. –Nitrogen moves through the food web and returns to the soil during decomposition.

geologic uplifting rain weathering of phosphate from rocks runoff sedimentation forms new rocks leaching phosphate in solution animals plants decomposers phosphate in soil The phosphorus cycle takes place at and below ground level. –Phosphate is released by the weathering of rocks. –Phosphorus moves through the food web and returns to the soil during decomposition. – Phosphorus leaches into groundwater from the soil and is locked in sediments. – Both mining and agriculture add phosphorus into the environment.