T77 Developments in Pollen Calibration and Quantitative Reconstruction of Past Vegetation Cover (Posters)
RELATIONSHIPS BETWEEN LANDCOVER AND POLLEN ASSEMBLAGES FROM SMALL DANISH LAKES AROUND AD 1800
Paper number: T77-3
Program: Technical Sessions
Time: 1:30 PM – 4:30 PM
Authors
Abstract
The aim was to improve the quantitative interpretation of fossil pollen diagrams from small lakes by estimating the size of the pollen source area and by testing methods of pollen-landscape calibration. A dataset of pollen assemblages from ca. AD 1800 from 30 small (3-30 ha.) Danish lakes, and landcover data from digitised historical maps surrounding the lakes has been collected and analysed using the Extended R-Value model and the Prentice-Sugita model of pollen dispersal, which are implemented in the POLLSCAPE simulation model.
The size of the Relevant Source Area of Pollen (RSAP) for the lakes is estimated. Wind speed and pollen dispersal characteristics are shown to have little effect on the RSAP, but there is a difference between the RSAP in eastern and western Denmark. Simulations using POLLSCAPE shows that this can be explained by differences in the patch size of the vegetation in the two regions.
Pollen assemblages simulated by the POLLSCAPE model using the historical landcover data and pollen productivity estimates from neighbouring countries are compared to the observed pollen assemblages, in an attempt to validate the model. This is complicated by uncertainties about the species composition of the different landcover types around AD 1800, which is the main disadvantage of using historical analogues in stead of a modern dataset. However, the POLLSCAPE model can reproduce the main trends in the observed data.