Why is the term linchpin appropriate in describing the termites

The term linchpin is appropriate in describing the termites as they are ecologically important for ecosystem. They play different roles.Termites being decomposers digest the cellulose present in the decaying plant matter, they convert cellulose into reusable form for plants. Termites fix nitrogen by digesting the nutrients in the soil and separates the nitrogen from the attached atoms which is easily taken up by the plants. Termites creates shelter for various insects colonies. They burrow deep inside the soil, creates tunnels suitable for insects colonies living.    

what's the

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.