Ecosystem productivity measures the rate of organic matter accumulation, categorized into primary and secondary productivity. Primary productivity involves the energy captured by autotrophs through photosynthesis, further divided into gross (total organic matter synthesized) and net primary productivity (energy available after respiration). Secondary productivity reflects energy storage at the consumer level, where only about 10% of ingested food is absorbed by higher trophic levels.

2. PRODUCTIVITY
● The productivity of an ecosystem refers to the rate of production, i.e., the
amount of organic matter accumulated in any unit time.
● Ecosystem productivity represents the total amount of energy (the
organic matter) fixed or stored by the autotrophs per unit time in
ecosystem .
● Measured as such as grams per square metre per day (g m−2
d−1
)
● It is of two types:
1. PRIMARY PRODUCTIVITY
2. SECONDARY PRODUCTIVITY

3. PRIMARY PRODUCTIVITY
➔ It is the rate at which the the solar energy
is stored or trapped by the autotrophs,
➔ In other words the amount of biomass or
organic food produced by autotrophs per
unit are during the process of
photosynthesis.
➔ These plants can make food because they
are photosynthetic due to presence of the
green pigment chlorophyll.
➔ These are further of two types:
1. GROSS PRIMARY PRODUCTIVITY
2. NET PRIMARY PRODUCTIVITY

4. GROSS PRIMARY PRODUCTIVITY
❖ GROSS means TOTAL PHOTOSYNTHESIS
❖ It represents the total organic matter
synthesised by the producers by
photosynthesis unit area and time.
❖ It includes the organic matter or basically
energy used up during process of respiration,
metabolism etc.
❖ It depends on the chlorophyll content
❖ estimated in terms of either chlorophyll
content as chl/g dry weight/unit area,
or photosynthetic number, i.e., amount
of CO2 fixed/g chl/hour.

5. NET PRIMARY PRODUCTIVITY
● Also known as NET ASSIMILATION
● It is defined as the amount of
energy or organic matter stored or
fixed at the first trophic level after
respiration that is available to the
higher trophic levels.
● NPP = GPP - RESPIRATION (OR
CELLULAR WORK)

7. RELATION OF SOLAR RADIATION AND
PRIMARY PRODUCTIVITY

8. SECONDARY PRODUCTIVITY
➢ This represents the energy storage at the
consumer level.
➢ The energy resulting from the primary
production furnishes the energy provided
to the rest of the higher trophic levels.
➢ Some of the energy in the form of food is
consumed by herbivores or carnivore
which are other eaten by the omnivore .
➢ Much of the ingested food is not
assimilated , only 10% of the food is
ingested and absorbed rest of it is excreted
out from the body.