Productivity

Productivity or how fast and organism grows Is the amount of biomass that has increased in a year, and is available for the next level of the food chain. (Primary Consumers)
 * Net primary productivity**

All the energy that the ecosystem can harness from the sun. Formula = Gross Primary Productivity - Respiration (Kj/m2/yr)
 * Gross Primary Productivity**

Energy Enters the ecosystem as a sunlight Only 2% of the light energy falling on a tress is captured and turns into chemical energy by photosynthesis. The rest is reflected or warms up the tree as it is absorbed.

Measured in joules (J). It is the energy captured or assimilated by an organism. For a pant it is te sunlight actually fixed by the leaves during photosynthesis. When light hits a plant energy is stored in leaf as sugars and starches, which later are used to form flowers or fruits.
 * Gross productivity is measured of total energy captured**

Plants have to use some of the energy captured to keep themselves growing: they move water and stored chemicals around They make hormones and enzymes to control their metabolism They make flowers, fruits, new leaves and stems.
 * Net Productivity**

The energy left over after they have used what they need is called the NET PRODUCTIVITY. The energy used by the plant for essential tasks is called respiration energyt, and eventually it is released to the environment as heat.


 * How are Gross and Net Productivity related?**

Net Productivity = Gross Productivity - Respiration Energy or NP = GP-R This equation applies to animals too.

GSP ...into animals -Faeces -Respiration

Food eaten - faeces

The productivity of a plant is called: Primary Productivity because are the first or primary organism in the food web.


 * Animal Productivity**

Animals must eat other organism to obtain energy unlike plants which photosynthesis. Animals may eat plants or animals or both. Not all the energy in food is absorbed (assimilated) into animals body. Unassimilated food is ejected as faeces or droppings.

So Gross Productivity = good assimilated

or

Gross Productivity = Food eaten - energy in faeces.

Net productiviry for an animal (Secondary consuymer)

Gross secondary productivity = Energy eaten - energy in faeces