(a) What is the primary productivity of an ecosystem and how is itexpressed ?

(b) Explain what does the equation given below show:

NPP = GPP – R

OR

(a) Name the type of detritus that decomposes faster. List any twofactors that enhance the rate of decomposition.

(b) Write the different steps taken in humification and mineralization during the process of decomposition.

A) The rate of biomass production is called productivity

Primary productivity is defined as organic matter production per unit area over a time period by plant (during photosynthesis)

It is expressed in

Weight g-2

Energy kcal m-2

Primary productivity can be dived into

1. Gross primary productivity 2. Net primary productivity

c) NPP = GPP – R

Its represents that net primary productivity is when gross primary productivity minus the respiration losses (R)

OR

a) Nitrogen and water soluble (such as sugars ) are the detritus that decomposes faster

•Warm and moist environment speeds up the decomposes

•O₂ level increases the decomposition speed

b) Humification –process of decomposition from plant remains

Mineralization – process where an organic parts are replaced by minerals

PROCESS

•Fragmentation – breakdown of detritus into smaller particles by earthworm (detritivores)

•Leaching – water soluble inorganic nutrients go down into the soil horizon and get precipated

•Catabolism – degradation of detritus into inorganic substances ( by bacterial and fungal enzymes)

•Humification – accumulation of a dark coloured amorphous substance called humus , undergoes decomposition (extremely slow)

•Mineralization – humus is further degraded by some microbes to release onorganic subastance