Tree Reproduction In Fragmented Tropical Forests

Introduction:

The acorn doesn’t fall far from the oak. It is common sense that a seedling near an adult tree is likely to be the offspring of that tree. However Preston Aldrich found that this pattern does not hold, at least for one tree species, in tropical rainforests that have been cleared or logged. He used a kind of paternity test to determine which trees in a fragmented forest mosaic had produced which seedlings. The point of the study was to see in what ways the disruption of the forest had changed the behavior of the trees’ pollinators and seed dispersers, and to see if the population genetics of the trees were altered.

The paternity tests revealed that most of the seedlings of the tree Symphonia globulifera were found in forest patches, not out in the clearings, and they were produced by the trees out in the clearings, not by the trees they were near. This spatial pattern could be explained by changes in the behavior of the tree's pollinators which are hummingbirds, and its seed dispersers which are bats.

The reproductive dominance by a few trees could have serious long term consequences for the genetic make up of the population. We spoke with Preston Aldrich, one of the authors of the Science paper in which this work was published, about tropical forest recovery patterns.

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