Ecology

• Biosphere – contains combine portions of the planet in which all life exists; abiotic and biotic

• Relationships within the biosphere, ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere

• Species – populations – communities – ecosystem - biome

methodologies

• Regardless of the tools they use, scientists conduct modern ecological research using 3 basic methods;

• observing, experimenting, modeling

Energy Flow

• Sunlight is the main source of energy for life on earth - photosynthesis

• Some life forms rely on the energy stored in inorganic chemical compounds (no carbon) chemosysthesis

• Energy flows through an ecosystem in one direction, from the sun/inorganic compounds to autotrophs and heterotrophs (food chains)

Cont.

• Only 10% of the energy available within one trophic level is transferred to organisms at the next trophic level

Cycles of Matter

• Matter is recycled within and between ecosystems

• Biogeochemical cycles: matter is not used up, it is transformed

• Water cycle – evaporation, condensation, precipitation

• Nutrient cycle – organisms need nutrients to build tissue and carry out essential life functions

Cont.

• Carbon cycle – key ingredient of living tissue

• Nitrogen cycle – required to make amino acids

• Phosphorus cycle – forms DNA and RNA

• Nutrient limitations – scares or cycles slowly

Ecosystems

• Biotic – biological factors

• Abiotic – physical factors

• Both determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives

• Niche – occupation

Interaction

• Community interaction, such as, competition, predation, and various forms of symbiosis can powerfully affect an ecosystem

• Ecosystems are constantly changing in response to natural and human disturbances.

• As an ecosystem changes, older inhabitants gradually die out, new organisms move in, causing further changes in the community

Cont.

• Primary succession – no soil exists

• Secondary succession – changes existing community without removing soil

• Pioneer species – the first to arrive (other than soil)

Biomes

• Tropical rain forest• Tropical dry forest• Tropical savanna• Temperate grasslands• Desert• Temperate woodlands and shrubland• Temperate forest• NW coniferous forest• Boreal forest (tiaga)• Tundra• Mountains and ice caps

Cont.

• Each biome has a characteristic climate and community of organisms which include but are not limited to:

• Abiotic factors

• Dominant plants

• Dominant wildlife

• Geographic distribution

Aquatic Ecosystems

• Aquatic ecosystems are determined primarily by the depth, flow, temperature and chemistry of the overlying water

• Freshwater; divided into two main types; flowing water and standing water

• Flowing water-river, streams, creeks, and brooks

• Standing water – lakes and ponds

Cont.

• Plankton – tiny free floating organisms (food)

• Phytoplankton – single celled algae supported by nutrients in the water and form the base of aquatic food webs

• Freshwater wetlands – bogs, marshes, swamps (fresh or salt water)

• Estuaries – rivers meet sea

Marine Ecosystems

• Photic – where photosynthesis takes place, limited to first 200m

• Aphotic – permanently dark, below 200m

• Marine biologist divide the ocean into zones based on the depth and distance from shore; intertidal, coastal ocean, open ocean

Cont.

• Intertidal – area where tides changes

• Coastal oceans – low tide mark to continental shelf (coral reefs)

• Open ocean – edge of continental shelf outward, largest marine zone, covers 90% of ocean

• Benthic – sea floor

Populations

• Geographic distribution, density, growth rate

• 3 factors can affect population size; births, deaths, and immigration/emigration

• Exponential growth – reproduction at a constant rate

• Under ideal conditions with unlimited resources, a population will grow exponentially

Cont.

• Logistic growth – when populations growth slows or stops following a period of exponential growth

• As resources become less available, the growth of a population slows or stops

• Carrying capacity – largest number of individuals that an environment can hold