In Ohio’s Wayne National Forest, December 27 is known as “sinking day.” The makeshift holiday comes just two days after Christmas when forlorn holiday trees begin showing up on curbs across the U.S. Several years ago, the U.S. Forest Service decided to take advantage of all the cast-off greenery and use it to fulfill a higher purpose: creating habitat for freshwater fish.
Each year, the USFS now gathers up hundreds of old trees, lashes them to cinder blocks, and drops them into Wayne National Forest’s Lake Vesuvius. Foresters elsewhere in Ohio—as well as in Texas, South Carolina, Missouri, and various other states—have similar traditions. Submerged trees, they say, create a sort of artificial reef, which gives a native fish critical structure that they can use to hide from predators. Evergreen boughs also create habitats for snails, macroinvertebrates, and other underwater critters. When it decomposes, the greenery provides a vital source of nutrients for many aquatic plants and insects that fish rely on for food.
While many lakes naturally have downed trees and other subterranean structures, man-made reservoirs tend to be relatively barren at the bottom, which makes it difficult for healthy fish populations to thrive. In these cases, fish seem to respond especially well to the sinking-day tradition. In the East Bay region of California, for example, underwater video footage shows various small fish species using the submerged trees for cover.
Since holiday trees decompose relatively quickly, there’s usually plenty of space at the bottom of the lakes to add more each year—which means plenty of opportunities to donate your tree to the cause. And if you don’t have a sinking-day program near your home, consider recycling your tree or putting it in your backyard instead. Small animals like rabbits love to take cover under downed evergreens, and birds often use needles and twigs to line their nests. It’s a great way to give your backyard wildlife a holiday gift of their own—one that keeps giving all year long.