Vegetational heterogeneity during a primary sand dune succession

The Grand Bend succession can be divided into three periods: a colonizing stage, up to 1600 years; a transition period from 1600 to 2900 years; and a persistent stage from 2900 to at least 4800 years. The colonizing stage is dominated by grasses, Juniperus spp. and Quercus prinoides. Transition begins when persistent species invade at certain points; the earliest species are usually Quercus velutina × rubra, Rhus aromatica, and Prunus virginiana. During the transitional period the patches of persistent vegetation grow until they coalesce. This marks the inception of the persistent stage during which the vegetation cover is predominantly oak–pine forest. Hence the path of succession does not differ from point to point but the rate of succession does. It is argued that the existence of distinct successional stages and the mode of transition between them support the organismal concept of vegetation.