When big trees fall over in a storm, their upended root masses can the raised six, ten or more feet in the air. They slowly rot over many years forming what’s called a tip-up or, after many decades, a pillow. (Alongside the pillow will be a depression where the roots used to be, the adjacent depression-and-mound are called, charmingly, “pillow and cradle”.)

A study in Wisconsin found that leaving these tip-ups alone after a storm, instead of “cleaning up” the forest, can help regrowth diversity:

They found that as these mounds decay and saplings begin to grow on them, their height relative to the main forest floor provides some protection from animal browsing. That means that certain tree species, especially those that are “light-seeded” – with seeds that are blown by the wind – have advantages to regenerate if some mounds are left intact.

They suggest that when harvesting fallen timber after a storm, some areas should be left alone to encourage diversity.

The story from the USDA Forest Service is here.

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