ABSTRACT
The ecosystem concept has deep roots in ecology. Modern ecologists tend to think of ecosystems in terms of energy flow, carbon flow or nutrient cycles. The first law of thermodynamics states that when energy is converted from one form into another, energy is neither gained nor lost. The first law is also called the law of conservation of energy. The second law of thermodynamics states that every transformation results in a reduction of the free energy of the system. The proportion of net primary production that flows along these pathways depends on transfer efficiencies in the way energy is used and passed from one step to the next. In the case of secondary consumers it is the percentage of herbivore productivity eaten by carnivores. The remainder dies without being eaten and enters the decomposer chain. Production efficiency varies according to the taxonomic class of the organisms concerned.
