The use of historical vegetation dynamics in interpreting prehistorical vegetation change

Abstract

Post-disturbance revegetation sequences documenting the reentry time and longevity of 26 forest species are outlined for five forests in northern South Island. These five forest sequences are compared with three theoretic models, the Initial Floristic, the Intermediate, and the Classical, which are each presented in two alternative cases to give a total of 12 basic models. The two alternatives incorporate either a Faciliation or Inhibition mechanism, and either a correlated or noncorrelated relationship between reentry time and species longevity. The results show that four of the five observed forest sequences fit the Intermediate Model; three of these have a Facilitation mechanism and one an Inhibition mechanism, and all are non-correlated. The fifth forest sequence closely resembles the Initial Floristic Model and has a Facilitation mechanism and a (non-significant) correlated relationship. Construction of a longer-term regeneration sequence with, in part, estimated disturbance recurrence times, showed a tendency for most recurrence times to be less than the life span of most species present. This conclusion brings into question the central hypothesis of the climax concept.

The use of modern regeneration sequences in identifying possible disturbance events in documented pollen diagrams is described for 28 woody species. I emphasize that the total species array should give the best evidence of possible prehistoric disturbances. I also suggest that in interpreting pollen or other prehistoric vegetation diagrams, information on modern post-disturbance regeneration sequences may be able to help separate the effects of disturbance from longer-term climate or soil changes and perhaps from short term climatic change as well.

Keywords:

• post-disturbance forest regeneration
• dynamic models
• climax critique
• reentry period
• maximum height age
• longevity
• pollen as disturbance indicator