What is the difference between natural and man-made ecosystems?

There are significant differences between agrobiocenosis and the natural ecosystem. An important property of the natural community is its sustainability. The environmental sustainability of agrobiocenoses is low. Without human participation, agrobiocenoses of grain and vegetable crops exist for no more than a year, agrobiocenoses of perennial herbs – 3 years, fruit crops – 20 years.
For a natural biocenosis, the only source of energy is the sun. Agrobiocenoses, in addition to solar energy, receive additional energy spent by a person on soil cultivation, weed control, pests and diseases of agricultural crops, fertilizer application, etc.
In the natural ecosystem, the primary plant production (crop), having passed through numerous food chains, returns to the biological cycle system again. In agrobiocenosis, such a cycle is disturbed, since most of the production is seized by a person during harvesting. As a result, you constantly have to take care of maintaining soil fertility by fertilizing.
Agrobiocenoses give humanity about 90% of food energy. However, with improper agricultural production, soil fertility is lost, salinization, desertification of vast territories and environmental pollution occur. Massive deforestation of agricultural land leads to serious negative changes in the biosphere.