– Biomass refers to the total weight of living matter that exist at each trophic level of an ecosystem at a particular time regardless of species. For example, all autotrophs (including autotrophic bacteria, grasses, trees, shrubs and herbs) belong to one level; all primary consumers (herbivores) at another level, etc. Biomass at each level decreases as one moves up the food chain (from producers to consumers)
Standing crop refers to the total weight of organisms belonging to a particular species in ecosystem at a given time. It’s species dependent for example, the total number of lions, elephants, grass, etc that can be harvested at a given time within a trophic level.