Justify the following statement in terms of ecosystem dynamics. "Nature tends to increase the gross primary productivity, while man tends to increase the net primary productivity". 

Explanation

Hints:
`"*"` Define ecological succession.
`"*"` In ecological succession, there is tendency towards increase in species diversity , complexity of organisms and gross primary productivity because producers of higher seral communities have more and more photosythetic efficiency.
`"*"` But in ecological succession, there is decrease in net primary productivity or annual yield which is antagonistic to the increasing demands of increasing human consumption . So human tendency is to increase the net primary productivity through organic farming , use of fertilizers , pesticides , etc.