Factors controlling the distribution of Tilia cordata Mill at the northern limits of its geographical range

SUMMARY The ages of trees of Tilia cordata Mill in the Lake District, which is close to the northern limit of the species in Britain, have been estimated by three methods. Estimates for the few old maiden trees are based on extrapolation of the relation between the diameter of the stem at 1‐3 m above the ground and the known age of planted trees. The diameter of young coppice‐stools is shown to be 1.8 times the diameter at 1.3 m above the ground of trees at the same age; this ratio is applied to large circular stools and their age then estimated. The age of stools with exposed roots has been estimated from measurements of the depth of exposure and of the recent rate of erosion. All three methods show that the age of many trees is of the order of 1000 years. There is therefore the possibility that they became established during earlier periods which were warmer than at present, such as that between A.D, 1 150 and 1300.