Seed production of Pinus sylvestris after release cutting

The effects of release cutting on cone, seed production, and seed quality w ere investigated in 1995-1996 among Scots pine (Pinus sylvestris L.) seed t rees in central Sweden. The effects of diameter, height, crown length, and age of trees on cone production were also examined. Cone and seed productio n were about five times higher in seed trees that had been released for 4 o r 5 years, compared with control trees in the unreleased forest. Seed trees released for less than 3 years had about the same level of cone production as the controls. After release, the number of cones increased more in the lower part of the tree crowns than in the uppermost 2 m. The mean 1000-seed weight, seed viability, and number of viable seeds per cone were not signi ficantly different between released and unreleased trees. In 1996, there we re about eight times more cones than in 1995, probably because summer tempe ratures were higher in 1994 than in 1993, the years when the respective flo wer buds were initiated. Within the investigated range of diameters, 250-43 0 mm at breast height, a 10-mm increase in diameter was correlated with a 1 0% increase in mean cone production. However, the variation in cone product ion between individual trees was considerable. Tree height, length of green crown, and tree age showed no significant correlations with cone productio n.