Studies of radial growth in Salix cinerea L. on a reservoir margin.
Increment cores were obtained at b.h. from the stems of 300 trees on the margin of the Lake Vyrnwy reservoir, Montgomeryshire, Wales, in 1969, and the annual rings were counted and measured. The distinctive age structure of the population round the margin, i.e. a high proportion of young trees (ca. 10 years old) near the dam, was possibly the result of an increase in the stability of the margin, favouring colonization of sites not previously available to seedlings. Within a given area, group age was inversely proportional to the strength of waves action. A regression equation is presented showing that increment is negatively correlated with age and duration of flooding of the root-crown (expressed as a % of the growing season). The study indicates that flooding is not necessarily directly important in inhibiting tree survival on reservoir margins. Wave action, with resulting instability of the margin, may be more important. [Cf. FA 3, pp. 671-688]