However, beginning in the 1920s scientists began refuting the notion of a climax state. By 1950, many scientists began viewing succession as a phenomenon that rarely attains equilibrium. The reason why equilibrium is not reached is related to the nature of disturbance . Disturbance acts on communities at a variety of spatial and temporal scales. Further, the effect of disturbance is not always 100 percent.
Many disturbances remove only a part of the previous plant community.
As a result of these new ideas, plant communities are now generally seen as being composed of numerous patches of various size at different stages of successional development. In this investigation, Billings examined the succession of plant species that occurred on abandoned agricultural fields in North Carolina. Billings studied a number of fields that had been deserted from just a few years to a maximum of about 150 years. From observations of the plant communities that existed in these sites, Billings was able to construct a detailed successional sequence. The annuals were then quickly replaced in dominance in the next year by biennial plants and grasses .