Which of the following elements has a much lower atmospheric input compared to carbon?

Given below is a list of autotrophs and heterotrophs. With your knowledge about food chain,establish various linkages between the organisms on the principle of 'eating and being eaten'. What is this inter-linkage established known as?
Algae,hydrilla,grasshopper,rat,squirrel,crow,maize plant,deer,rabbit,lizard,wolf,snake,peacock,phytoplankton,crustaceans,whale,tiger,lion,sparrow,duck,crane,cockroach,spider,toad,fish,leopard,elephant,goat,nymphae,spirogyra.

The food chain in which microorganisms break down the food produced by primary producers is known as:

The biotic part of the ecosystem includes:

Energy contents of macrophytes may be estimated by

Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?