Seed Crops

Every naturalist knows that tree-fruit crops vary greatly in size from year to year (Figure 18.1). In some years trees and shrubs are laden with seeds and fruits of

Figure 18.1 The mean number of Norway Spruce Picea abies cones per tree each year in southern Sweden, 1909-1967. From Hagner (1965) and Gotmark (1982).

Figure 18.1 The mean number of Norway Spruce Picea abies cones per tree each year in southern Sweden, 1909-1967. From Hagner (1965) and Gotmark (1982).

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