Timing of shedding seeds and cones, and production in different stands of Scots pines at Abernethy Forest Scotland

Abstract

A study was carried out over 11 seed years on the timing of shedding of seeds and cones, and annual seed fall and cone production in three stands of native Scots pinewood and a Scots pine plantation in Abernethy Forest, Scotland. Peaks in seed fall took place mainly in May, and cones were shed mainly between June and August. There were few residual seeds remaining in shed cones. Synchronized peaks in seed fall and cone production (mast years) took place at 3-year intervals across the different stands. The difference between cohorts of high and low cone production ranged from factors of 5 to 20 among sites. Coefficients of variation for cone production ranged from 62 to 84 per cent among sites. There were no significant differences in cone production among sites, but there were site-related differences in seed fall. The larger canopy cover in the plantation probably accounted for the higher seed fall per square metre there, though variations in the amount of seed eaten by birds and mammals may also have been important. Canopy cover needs to be considered when converting cone densities under crowns to cone density per unit of woodland area. A similar calculation is difficult for seeds because they are lighter than cones and many fall outside the area under the crowns. The results are discussed in relation to the potential for tree regeneration and the availability of food for birds and mammals prior to seed dispersal. © Institute of Chartered Foresters, 2005. All rights reserved.