Depositional frequency of German subfossil oaks: climatically and non-climatically induced fluctuations in the Holocene

Abstract

A highly resolved record of the depositional frequency of subfossil trees since 8263 bc in the valley of the River Main is presented. Different aspects of forest dynamics are explored including depositional anomal ies (phases of low or zero departures), changes in forest density based on tree growth trend classes (GTCs), and regeneration using mean lifespan (ML) data. This reveals a number of climatically induced environmental changes that are synchronous with events in the North Atlantic region and therefore may reflect a facet of the North Atlantic climate system. Three periods are recognized: (1) pre-3500 bc, when depositional frequency was dominated by climatic events with notable anomalies at 6200 and 4100 bc; (2) between 3500 and 1200 bc, when climatically triggered events were enhanced by forest clearances, especially marked anomalies occurring around 2700, 2300 and 1700 bc; and (3) post-1200 bc, when the climatic information is obscured by human activities.