tree tip pit
When a tree falls, its upended root ball leaves a depression as well as a mound of earth made of the displaced material. In the Paciﬁc Northwest, tree tip pits are common sights, as the ubiquitous Douglas ﬁr has a shallow root system (owing to the abundance of water falling on the ground) and is prone to fall over more easily than other large trees. Both pits and mounds are microhabitats for all kinds of forest inhabitants. In wet seasons, the pits act as small catchment ponds for birds oranimals that need a drink. Squirrels and other rodents use the soft mounds as a cache for their collected nuts and food. At the end of winter in the Tongass National Forest, a black bear may take refuge in the pit, pushing over the log to look for grubs while her two cubs play on the mound—or she might take a nap under the prow of the tree’s trunk. Perhaps that is why the tree tip pit is also referred to as a cradle and knoll. In general, tree tip sites can be indicators of old-growth forests, since slim young trees with tap roots usually resist the kinds of winds that blow the heavy old trees down.