Hi Praveen :

Primary Succession can be defined as the process of growth in an area that was previously uninhabited, barren, unoccupied and there was no initial vegetation. On the other hand,

Secondary Succession can be defined as the growth of the community in such area which was previously occupied, inhabited and that has primary vegetation but got disturbed or damaged due to some external or internal factors.

The example of Primary Succession is the newly formed bare rock, desert, ponds, etc.

The area covered under deforestation, or affected by natural calamities such as flood, earthquake, etc. are the examples of Secondary Succession .

Hope this was helpful!

The rate of production of organic matter during photosynthesis is called Gross Primary Productivity (GPP) of the ecosystem.

When respiratory losses (R) is subtracted from GPP, we get Net Primary Productivity (NPP). Net primary productivity is the available biomass for the consumption of heterotrophs.

GPP = 300 kcal

R = 20% of GPP = 20/100x300 = 60 kcal

NPP = GPP - R

= 300-60

= 240 kcal

Hello Ravichandran!

Ecology and environment is a really interesting chapter in CBSE class 12th biology subject. The concept including primary and secondary productivity is GPP - RL = NPP i.e., gross primary productivity minus the respiratory losses equals net primary productivity. But, sorry to say, in order to get the answer of the question you have asked, you would have to restructure your question. The question is not clear about what do you want to find out. It's a request , kindly restructure your question and ask again. We are ready to help you 24/7.

Good luck!