Palaeoclimates and Their Consequences on Forest Composition

Abstract

The analysis of most plant populations in natural forests clearly retraces the mechanisms of sylvigenesis, based on the occurrence of small-scale incidents — in particular treefall gaps — more or less regularly distributed in time and space (van der Meer et al. chapter 24). However, a number of ‘anomalies’ detected in the population structure or in the distribution of some species cannot be adequately explained by the internal dynamic processes which occur on the century time scale. Plants react at different speeds to perturbations, and major events, even very ancient ones such as the perturbations recorded in the sediments, have probably also left a durable mark in the present organisation of the vegetation. We can therefore hypothesise that relatively ancient events, which would have occurred on a much larger scale than treefall gaps, would have caused large modifications of the forest ecosystems and left long-lasting tell-tale signs.