Vegetation science concepts I. Initial floristic composition, a factor in old-field vegetation development with 2 figs.

Summary

Two principles are considered as being involved in vegetation development on abandoned agricultural lands. The first, called Relay Floristics, involves a succession of incoming and outgoing plants, each group invading the land, ousting its predecessor, and in turn preparing the site so as to be ousted itself. This is the conventional interpretation of “old-field plant succession”, but is considered by the author to be in many cases a very minor principle. The second principle is called Initial Floristic Composition, and refers to that element which invades or has invaded at the time of abandonment. Following abandonment, there is a progressive development, with the forbs and grasses assuming predominance first, and the trees last. An evaluation of the relative importance of these two principles is necessary in Vegetation Management. For example, with Init. Flor. Comp. primary, the selective elimination of some elements of the flora can produce new and often stable plant communities. Thereafter such communities change only by the very different and often slowly acting principle of Relay Floristics. Relay Floristics itself can be modified and controlled by encouraging those plant covers which are most or least resistant to invasion to incoming relays of significance to the management plant.