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 53 animal dispersal DHJanzen100821.jpg high resolution
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| Animal-dispersed seed shadows have a very different dynamic than wind-dispersed seed shadows, one that is important in how an abandoned pasture or field fills with young forest. The very large Enterolobium cyclocarpum tree on the upper left side of this tree is about 55 years old. All the other trees in the clump of forest around it are younger. They are also almost all animal-dispersed. The phenomenon is that when there is a single tree in a pasture (such as this Enterolobium, undoubtedly planted there throug defecation by a horse or cow), birds and bats roost or perch in the tree. When a bird launches into flight, it commonly defecates, which creates a small concentration of seed shadows of many species below and in the vicinity of the Enterolobium tree. If a frugivorous bat roosts there to eat a fruit, it may defecate small seeds, or simply drop large ones after eating off the edible pulp. Coyotes and peccaries rest in the shade below such trees as well, and coyotes defecate their territory marking dung there too. All these activities produce a growing patch of animal-dispersed seeds in an abandoned fire-free pasture (or even in a heavily grazed pasture, where the fires are very light). This is a very different pattern of forest invasion of a pasture from that created by upwind seed-bearing trees. | ||
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