Ecology Module 15

Organization of the Biosphere Levels of organization Biosphere Biome Ecosystem Biotic factors – living Abiotic factors – non living Community Population Organism

The ecological “niche” Every organism in a community has a specific NICHE: The organism’s ROLE in the ecosystem - Habitat Place in food web Interrelationships

Transfer of Energy An ecosystem’s ultimate source of energy is the SUN Solar energy is used by “producers” to make food. “Consumers” eat producers (or other consumers) to gain food. Each step in the food web is called a TROPHIC LEVEL

Transfer of Energy Arrows show the transfer of energy from one organism to another Energy moves in ONE DIRECTION!

Transfer of Energy Ecological Efficiency Only about 10% of the available energy in one trophic level is passed to the next trophic level The “lost” energy is used for biological work (eating, growing, respiring, etc) and is converted to HEAT. Tertiary consumers LEAST energy Secondary consumers Primary consumers Producers MOST energy

Cycling of Matter Role of Decomposers Break down wastes and dead organisms Decomposition allows nutrients to be returned to the soil and reused Includes bacteria, fungi, and some invertebrates

Biogeochemical Cycles Water Cycle: Nitrogen Cycle:

Biogeochemical Cycles Carbon Cycle: Driven by photosynthesis and cellular respiration Decomposition is a form of cellular respiration Fossil fuel combustion adds CO2 to atmosphere Deforestation removes trees that should remove CO2

Community Interactions Competition Predation Symbiosis Organisms in a community interact with each other in many ways. Some of these interactions include: Competition Predation Symbiosis

Community Interactions Competition A struggle for resources (food, space, abiotic factors, mates)

Community Interactions Predation Some organisms (predators), consume others (prey)

Community Interactions Symbiosis A close, permanent relationship between 2 organisms – NOT predation or competition! Mutualism (+,+) Parasitism (+,-) Commensalism (+, 0)

Population Growth J-Curve: S-Curve: Carrying Capacity: The maximum number of individuals an environment can support Exponential growth: rapid growth in a short period of time # organisms # organisms Time Time

Limiting Factors – establish carrying capacity and limit the size of a population Density Dependent: Includes food, disease, mates Density Independent: Includes natural disasters

Population Growth Populations fluctuate around the carrying capacity…. This is called “dynamic equilibrium”.

Change in COMMUNITIES over time Succession: Communities change over time in a predictable, orderly way over many decades Changes in plant communities lead to changes in animal communities