BZU.Bahadur Sub Campus Layyah

MEASURING THE PRIMARY PRODUCTION PROCESS OF ECOSYSTEM

Primary production• Primary production is the synthesis of organic

compounds from atmospheric or aqueous carbon dioxide• It principally occurs through the process of

photosynthesis• it also occurs through chemosynthesis, which uses the

oxidation or reduction of chemical compounds as its source of energy.

• Almost all life on earth directly or indirectly reliant on primary production.

Primary production

• The organisms responsible for primary production are known as primary producers or autotrophs, and form the base of the food chain.

• In terrestrial ecoregions, these are mainly plants, while in aquatic ecoregions algae are primarily responsible

Gross primary production and net primary production

• Gross primary production (GPP) is the amount of chemical energy as biomass that primary producers create in a given length of time.

• Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues (i.e., "growth respiration" and "maintenance respiration").

• The remaining fixed energy (i.e., mass of photosynthate) is referred to as net primary production (NPP).

Terrestrial production• On the land, almost all primary

production is now performed by vascular plants with a small fraction coming from algae and non-vascular plants such as mosses and liverworts

Oceanic production

• in the oceans, almost all photosynthesis is performed by algae, with a small fraction contributed by vascular plants and other groups.

• Algae encompass a diverse range of organisms, ranging from single floating cells to attached seaweeds.

• They include photoautotrophs from a variety of groups. Eubacteria

Light

• The sunlight zone of the ocean is called the photic zone .

• This is a relatively thin layer (10–100 m) near the ocean's surface where there is sufficient light for photosynthesis to occur.

• For practical purposes, the thickness of the photic zone is typically defined by the depth at which light reaches 1% of its surface value.