1 The work examines the growth and photosynthesis of saplings and matu
re trees of Pinus sylvestris L. along an altitudinal gradient in the C
airngorm Mountains of Scotland. 2 Meristem temperatures of seedlings d
eclined with altitude, but an especially sharp decline was sometimes o
bserved at the tree-line. 3 Growth, measured as shoot length, needle l
ength and needle (fascicle) number, declined with altitude. 4 Extensio
n growth could be related to temperature using regression analysis. Ho
wever, the number of fascicles formed in a given year was related to t
he temperature of the previous summer. 5 Substantial losses of first-y
ear needles were observed over the winter. 6 In the early part of the
year, photosynthetic performance in the valley population was superior
to the tree-line population, both in the current- and previous-year's
needles. 7 The results are discussed in relation to the likely impact
of increasing temperatures on the productivity of the species.