Is it possible to reconstruct local pre-sence of pine on bogs during the Ho-locene based on pollen data? : a study based on surface and stratigraphical samples from three bogs in southern Sweden
Abstract: Horizons rich in subfossil stumps and roots of Scots pine (Pinus sylvestris) are frequently found in stratigraphies of northern European peatlands, providing clear evidence of Holocene periods with favourable conditions for bog-pine growth. The pines could only grow when bog-surface wetness was sufficiently low, and the presence of their remains is therefore a good indicator of past climatic conditions, mainly precipitation. Ad-amsson (2013) carried out a macrofossil study on Stass Mosse, a bog in central Scania, southern Sweden, and investigated peat-stratigraphical evidence of hydrological changes on the bog in the period 6000-3300 cal BP. The aim of the present thesis was to investigate if the presence of bog-pines at Stass Mosse, as reflected by sub-fossil stumps and macrofossils, can also be detected by pollen analysis of the same peat samples as analysed by Adamsson (2013). To facilitate interpretation of the stratigraphical pollen data, a complementary pollen study was made of surface samples from Fäjemyr in north central Scania. Samples were taken along a transect from the dense Pinus forest at the edge of the bog to the centre of the bog where pine trees were scarce and low in stature. The data from the site were analysed to identify any relationships between vegetation cover and pollen percent-ages and influx values. In addition, a surface sample from Store Mosse, a large bog in Småland further north within southern Sweden and without local presence of bog-pines, was included to further help interpretation of the pollen record from Stass Mosse. The results from Stass Mosse show that the pollen percentages and influx values generally increase at the same levels as the increases in macrofossils. Stass Mosse had generally low pine pollen percentages and influx values compared to Fäjemyr, and that might be caused by less favourable growing conditions on the bog, influencing pollen productivity. Fäjemyr did not have any consistent pattern between the number of local pines and pine pollen percentage or influx values in surface samples from the sites located at different distances from the dense pine forest at the edge of the bog. The reason is probably differences in moss growth at the different sites, and also there are dominantly regional pollen deposition at the sites. The results from the three peat lands show that it is not possible to identify the local presence of bog-pines only based on pollen data.
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