The basic or primary productivity of an ecological system is defined as the rate at which energy is stored by photosynthetic and chemo-synthetic activities of producer organism in the form of organic substances which can be used as food material. The producer organisms are cheaply green plants. If photosynthesis were the only process occuring in plants, we could measure production by accumulation of carbohydrates but unfortunately, at the same time plants perspire using energy for maintenance activities.
