Unusual vegetation stability in a lowland pine forest area (Doksy region, Czech Republic)

Although the Holocene is characterized by prominent vegetation changes, some vegetation types can reveal surprising stability. We studied Holocene woodland history in a sandstone pseudokarst area (Doksy region, Northern Bohemia, Czech Republic). Twelve soil profiles collected under native or semi-cultural pine forests were analyzed using anthracological methods. In seven of them, the age of profile bases was established using radiocarbon dating. All analyzed samples show a high degree of mutual similarity of species composition regardless of the site or the depth of the sampled soil layer, as well as a good concordance between the composition of fossil and contemporary vegetation. Forest vegetation dominated by Pinus sylvestris with a low but regular occurrence of Picea abies, Quercus sp. and Vaccinium sp. has prevailed since late Boreal up to the present. No considerable vegetation changes were detected during this period, except for succession after fire events. A high content of charcoal within soil profiles indicates that the study area has been affected by forest fires through a substantial part of the Holocene. Recurrent wildfires probably represented a crucial factor sustaining pine forests by cyclic succession, although the relative contribution of human versus natural causes of fire cannot be assessed. In earlier phases of the Holocene, the prevalence of pine in the local vegetation was revealed using palynological data, so that we can conclude that the pine-dominated forests ecosystem existed during the entire Holocene in the study area. This pronounced vegetation stability contrasts sharply with the changeable historical vegetation of Central European lowlands.