Biomass is biological material produced by plants living or deceased. It is often called biomass in a way of referencing it as a fuel. But as it relates to trophic levels, it changes forms. It can begin as wood or plant matter, wood chips or green plant waste.
As biomass moves up a trophic level, it is generally consumed and turned into energy or fuel for the consuming organism. As an example, grasses are biomass and are consumed by herbivores which turn it into fuel and other materials used in their bodies. They are then consumed by predators that do the same thing with the energy and materials originally produced by the plants.