1.2: Levels of Organization and Productivity

levels of organization

• nature is organized into hierarchies

• levels of organization: the different levels of hierarchies into which nature is organized

• cell: a minute compartment within which the processes of life are carried out \n

the focus of ecology

• biological organizations

• species: all organisms of the same kind that are genetically similar enough to breed in nature and produce live, fertile offspring

• population: all members of the same species living in a given area at the same time

• biological community: several populations of different species that live together and interact with one another in a particular place

• ecosystem: a specific biological community (biotic factor) and its physical environment (abiotic factor) interacting in an exchange of matter and energy

• biotic factor: the living parts of an ecosystem

• abiotic factor: the nonliving parts of an ecosystem

primary production and gross primary productivity

energy flow

• the flow of energy within an ecosystem starts with the trapping of solar energy by the producers through photosynthesis

• sunlight → organic matter (sugars)

  • primary production: the initial capture of solar energy by producers in an ecosystem
  • autotrophs perform primary production.

• gross primary productivity (GPP): the rate by which chemical energy is produced by autotrophs

  • autotrophs keep some of the energy produced through cellular respiration for themselves
  • this energy is used to create biomass (eg. roots, stems, leaves) which contains energy available to the following trophic levels

• net primary productivity (NPP): the energy (or biomass) that remains in an ecosystem after autotrophs have used enough for their own maintenance through cellular respiration

  • the energy available for heterotrophs
  • biomes and NPP: \n

Formula: GPP - Cellular Respiration = NPP

factors that influence productivity

• may be light, temperature, precipitation, availability of inorganic nutrients

• inorganic nutrient: an element or compound that organisms need for survival

• eg. phosphorus, nitrogen

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