ABSTRACT
Natural ecosystems, of which humans are a part, are fundamentally a network of solar energy and mineral fl ows. Green plants capture solar energy and convert it into chemical energy for use by themselves and the remainder of the biological system using the elements of carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and others. The food supplied by plants in the ecosystem is basic to the survival of all animals, including humans. It is the foundation of the entire life system. Some of the solar energy plants convert into stored chemical energy is passed on to herbivores and parasitic microbes. The success of agriculture and forestry is measured by the amount of solar energy captured as biomass in crops and forests. The biomass yield depends on the manipulation of these plants-which need fertile soil, water, and a favorable climate-using human, animal, and fossil fuel power for tilling, planting, weed control, harvesting, and various other activities.
