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STUDIES IN THE VEGETATIONAL HISTORY OF SCOTLAND
Author(s) -
BIRKS HILARY H.
Publication year - 1972
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1972.tb01285.x
Subject(s) - radiocarbon dating , juniper , geology , holocene , vegetation (pathology) , solifluction , shore , moorland , ecology , glacial period , physical geography , archaeology , geography , oceanography , forestry , geomorphology , biology , medicine , pathology
S ummary Loch Maree, West Ross, is in an area of outstanding floristic and vegetational interest today. Native pinewoods occur on the south shore, and the largest northern oakwood on the north shore. High ground supports a range of montane communities. A pollen diagram is presented from the upper 460 cm of a 542 cm continuous core from Loch Maree. Six radiocarbon age determinations have been made from the sediments in relation to pollen stratigraphical changes. The constant sedimentation rate thus revealed has been used to interpolate ages for other events in the pollen diagram. During the last 9000 years of organic sedimentation in Loch Maree, many changes have occurred in the flora and vegetation of the landscape. After the instability at the end of the last glaciation, a climatic amelioration allowed juniper scrub colonization and organic soil development. Birchwoods, with some hazel, succeeded juniper, followed by the entry and rapid attainment of dominance by pine on all acidic soils, especially on the south shore of the loch, at about 8250 radiocarbon years ago. Meanwhile oakwoods with some ash and elm, developed in areas of more favourable soil and microclimate on the north shore. Alder immigrated and rapidly occupied all suitable habitats at about 6500 radiocarbon years B.P., and the pine forest began to degenerate. This process culminated in its rather rapid replacement by moorland and bog, perhaps due to climatic changes, at about 4200 radiocarbon years B.P. AS the oakwoods declined at the same time, human activity may have been an additional factor. However, there is little evidence for subsequent human interference in the area. The constant sedimentation rate suggests that deforestation was primarily by natural means, rather than by burning, felling, or grazing. Comparisons with pollen diagrams from other areas reveals an area of West Ross with a consistent Flandrian pollen stratigraphy. To the north and west, Betula and Corylus are the most important tree pollen types. In the eastern Highlands, Pinus pollen is again dominant, but the time of its expansion and the arrival of Alnus is different. The floristic composition of the pollen diagrams also differs, particularly in the abundance of pteridophytes.