The position of agricultural ecosystems among the ecosystems of contemporary biosphere and their productivity

Abstract

The authors divide the ecosystems of contemporary biosphere into two great series: A) the series of natural ecosystems and B) the series of man-made ecosystems (see fig.1) may be separated according to the amount of energy that may circulate through (the so called energy flux). Natural ecosystems may have a lower or a higher energy flux. Man-made ecosystems have a comparatively higher flux, but some of them (some silvo-systems, agro-ecosystems, and water ecosystems controlled by man) are productive from a biological point of view whereas others (the ones in villages, towns, as well as other kind of systems built up by man) are great consumers of organic substances and other natural resources. A classification of agro-ecosystems according to the output/input ratio of "cultural energy" is evinced (see fig. 2). The authors distinguish three groups of agro-ecosystems: I) Industrial agro-ecosystems; II) Intensive agro-ecosystems; III) Extensive agro-ecosystems.