Where civilization thought it could cut itself off from natural habitat

This is how Shepard describes the decline of agricultural civilizations. A sad fate that might well be ours if we don’t quickly change course:

The cycle typically began with the concentration of authority and organization manifested through war expansion, territoriality and the establishment of irrigation systems and water reserves. The productive soil surface was increased by carefully managed water distribution. Irrigation gradually replaced complex and highly branched hydraulic systems. When the population grew beyond the available resources, the migrants moved to the heights, along the steps of coalminers and loggers, and settled, for the most part, as breeders in the valleys along the tributaries of the great rivers, such as the Tiger and Euphrates. Over the years, their herds grew, trampled and undisturbed the mountain slopes, destroying their vegetation and eroded the soil. The land lost its water retention capacity, which increased the leaching after the rains and lowered the groundwater supply to sources and wells. The seasonal variation in water resources was exacerbated by this succession of floods and shortages. The silt threatened to congest water retention and the kilometres of sophisticated water duct systems on which agriculture depended.

The culture, once all the ploughable land was occupied, intensified. Monocultures, pest and adventitious control, and the increased intensity of what was required of the soil, created all the conditions conducive to periodic eruptions of plant diseases and invasions of plagues and parasites whose wild food had been eradicated. Micronutrient deficiencies and soil salinization also favoured debacle.

Extract from the book Nature and madness, Chapter 1: The desert fathers