WHAT CONTROLS VEGETATION PATTERNING IN SCOTLAND? A LONG TERM PERSPECTIVE

Aim: The aim of the present study was to use pollen data in order to reconstruct past vegetation character and changes in Scotland on a regional basis. In doing so, the study was designed to analyse the drivers of vegetation patterning and determine the factors which influence this in order to support modern day conservation efforts. Location: Scotland, UK. Methods: Pollen data was sourced from 67 sites in Scotland that spanned 10900 to 100 Cal. yr. BP. Taxonomy was harmonised between records and pollen data from individual sites were resampled into 200 year time windows to facilitate analysis. A clustering analysis was undertaken in R in order to determine patterns of vegetation that could be mapped in space and time. Environmental variables for each pollen site were also collated and a clustering analysis was performed on these data to group sites were similar in terms of climate and topography. A human population data proxy for the region was used in the study; this took the form of summed 14C radiocarbon date densities from archaeological sites in Scotland. Results: Natural processes and climate limitations were primarily responsible for vegetation patterning (and changes) until the arrival of early agriculture in 6000 Cal. yr. BP, when anthropogenic land clearance began to effect land cover change. Anthropogenic influence became particularly significant from 4100 Cal. yr. BP onwards, with an increased prevalence of a heterogeneous semi-open birch/heather/grassland plant community across Scotland as a whole. Main conclusions: The study revealed that land cover in Scotland has changed since 10900 Cal. yr. BP both spatially and temporally. The original hazel/birch woodland that covered much of Scotland in the early Holocene has been anthropogenically cleared and fragmented, leaving a more open, heterogeneous environment with much reduced tree cover. This analysis of the pollen record enables interpretation of the various “states of naturalness” that have existed in the region and serves as an archive of plant community types that can be used to better optimise modern conservation and management practices in Scotland