Air moves easily through the soil and steals the moisture before seeds can germinate. Animal impact can compact the soil and allow seeds to germinate. Bennet Hills, Idaho. I worked in the Great Basin Desert of Idaho for some time where the wild onions grew by the tens of thousands across the denuded landscape. Like other low-successional species, they have a short growing cycle.
Onions are among the first plants to turn green in the spring.
They grow fast, bloom early and set seed almost by the beginning of summer. They are adapted to exposed soils where rain water quickly runs off the land, and any remaining moisture is easily dried up by the sun. The plants are done and dead early in the season while higher-successional plants are just getting started. Merely manipulating the soil with hooves would tighten the plant cover, and the onions would disappear as quickly as they came. Don and Cleo Shaules, ranchers near Billings carefully managed their livestock to advance succession on their land.