Productivity of an Ecosystem | Environment for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


PRODUCTIVITY 
 
Page 2


PRODUCTIVITY 
 
A constant input of solar energy is the basic 
requirement for any ecosystem to function and 
sustain.  
Primary production is defined as the amount of 
biomass or organic matter produced per unit area 
over a time period by plants during 
photosynthesis.  
It is expressed in terms of weight (gm –2) or energy 
(kcal m –2).  
The rate of biomass production is called 
productivity. 
 It is expressed in terms of gm –2 yr –1 or (kcal m –
2) yr –1 to compare the productivity of different 
ecosystems. 
Page 3


PRODUCTIVITY 
 
A constant input of solar energy is the basic 
requirement for any ecosystem to function and 
sustain.  
Primary production is defined as the amount of 
biomass or organic matter produced per unit area 
over a time period by plants during 
photosynthesis.  
It is expressed in terms of weight (gm –2) or energy 
(kcal m –2).  
The rate of biomass production is called 
productivity. 
 It is expressed in terms of gm –2 yr –1 or (kcal m –
2) yr –1 to compare the productivity of different 
ecosystems. 
It can be divided into 
Gross primary productivity (GPP)  
Net primary productivity (NPP) 
Gross primary productivity of an ecosystem is the 
rate of production of organic matter during 
photosynthesis.  
A considerable amount of GPP is utilised by plants 
in respiration.  
Gross primary productivity minus respiration 
losses (R), is the net primary productivity (NPP). 
 GPP – R = NPP  
Net primary productivity is the available biomass 
for the consumption to heterotrophs 
(herbiviores and decomposers).  
Page 4


PRODUCTIVITY 
 
A constant input of solar energy is the basic 
requirement for any ecosystem to function and 
sustain.  
Primary production is defined as the amount of 
biomass or organic matter produced per unit area 
over a time period by plants during 
photosynthesis.  
It is expressed in terms of weight (gm –2) or energy 
(kcal m –2).  
The rate of biomass production is called 
productivity. 
 It is expressed in terms of gm –2 yr –1 or (kcal m –
2) yr –1 to compare the productivity of different 
ecosystems. 
It can be divided into 
Gross primary productivity (GPP)  
Net primary productivity (NPP) 
Gross primary productivity of an ecosystem is the 
rate of production of organic matter during 
photosynthesis.  
A considerable amount of GPP is utilised by plants 
in respiration.  
Gross primary productivity minus respiration 
losses (R), is the net primary productivity (NPP). 
 GPP – R = NPP  
Net primary productivity is the available biomass 
for the consumption to heterotrophs 
(herbiviores and decomposers).  
Page 5


PRODUCTIVITY 
 
A constant input of solar energy is the basic 
requirement for any ecosystem to function and 
sustain.  
Primary production is defined as the amount of 
biomass or organic matter produced per unit area 
over a time period by plants during 
photosynthesis.  
It is expressed in terms of weight (gm –2) or energy 
(kcal m –2).  
The rate of biomass production is called 
productivity. 
 It is expressed in terms of gm –2 yr –1 or (kcal m –
2) yr –1 to compare the productivity of different 
ecosystems. 
It can be divided into 
Gross primary productivity (GPP)  
Net primary productivity (NPP) 
Gross primary productivity of an ecosystem is the 
rate of production of organic matter during 
photosynthesis.  
A considerable amount of GPP is utilised by plants 
in respiration.  
Gross primary productivity minus respiration 
losses (R), is the net primary productivity (NPP). 
 GPP – R = NPP  
Net primary productivity is the available biomass 
for the consumption to heterotrophs 
(herbiviores and decomposers).  
Secondary productivity is defined as the rate of 
formation of new organic matter by 
consumers. 
 
Secondary productivity is done by consumers 
via assimilation of the food they take.  
Since not all the primary biomass is consumed; 
and since not all the consumed is digested; 
secondary production is only a fraction of 
primary production.