Tree growth and climatic cycles in the rain shadow of the Grampian mountains

Abstract

TREE-RING widths have been widely studied as a guide to historical meteorology^1,2, the assumption being that fluctuations superimposed on the smooth progression of change with age are climate induced. Several authors^3,4 have even identified cyclical patterns in tree growth, some of which they have tentatively linked to sunspot activity, but generally the precise climatic parameter that may be operating remains unspecified. In Scandinavia, ring widths seem to fluctuate with summer temperature^5,6, although precipitation during early summer may also be influential⁷. In Scotland, on the other hand, Schove and Frewer⁸ were unable to relate any meteorological character to the growth pattern of native Scots pine (Pinus sylvestris L.) on Speyside. Here we report, however, that examination of the results from two long term fertiliser experiments in mature Scots pine at Alltcailleach forest (National Grid Reference NO 3596), on upper Deeside, has shown that growth exhibits several regular oscillations each of which can be related to a particular climatic cycle. Furthermore, it would seem that some of these climatic cycles may be limited to low rainfall areas, such as the rain shadow of the Grampian mountains.