How much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores?

Answer: dSolution: In a predator or grazing food chain predation occurs at every steps. Like herbivore are eaten up by carnivore. if they die naturally, then the energy trapped in the body of herbivore (or any tropic level) is transferred to decomposers.
Only 10% of herbivore productivity is utilised for raising productivity of next tropic level (primary carnivores). while the rest 90% is eaten and used up, in process like respiration, maintenance of body heat and other activities.