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
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