CLIMATIC-CHANGE, HUMAN INFLUENCE AND DISTURBANCE REGIME IN THE CONTROL OF VEGETATION DYNAMICS WITHIN FIBY FOREST, SWEDEN

1. The immigration and rise to dominance of Picea abies within Fiby Forest, Sweden, was investigated by pollen and charcoal analysis of tiny (c.1-m2) bogs which contained a 4000-year record. 2. A mixed deciduous forest that existed 4000 years ago was replaced in a stepwise manner by a boreal community. The detailed dynamics of the changeover were controlled by catastrophic disturbances 2500 and 2200 years ago. 3. Two long periods of disturbance by burning and grazing kept the woodland open in structure. Eventual abandonment of this management practice initiated a succession that resulted in the present dominance of Picea, over 2000 years after its immigration into Fiby. 4. A model is presented describing the role of disturbance in facilitating the response of vegetation to climatic change.