By Nancy Duncan, Natural Resource Program Manager, Mississippi National River and Recreation Area

A plot of nearly 50 cottonwoods, planted with Mississippi Park Connection and volunteers at North Mississippi Regional Park in 2014 to restore an area impacted by a tornado, was recently destroyed by beaver in a matter of days, despite having been e… — A plot of nearly 50 cottonwoods, planted with Mississippi Park Connection and volunteers at North Mississippi Regional Park in 2014 to restore an area impacted by a tornado, was recently destroyed by beaver in a matter of days, despite having been enclosed in fence. Photo credit: National Park Service

As a result of the fur trade, many areas of the country saw beaver disappear from the landscape during the 1800’s. Recognizing their value, states successfully reintroduced them and they are once again flourishing.

Photo credit: National Park Service. Floodplain backwater showing Beaver dam — Photo credit: National Park Service

When most of us think of beaver, we think of them building dams and lodges, creating ponds where they raise their kits. Along a river the size of the Mississippi, however, they tend to build dens in the river bank that begin below water, and then angle upward, extending under tree roots into a dry central chamber a foot or two above the water line, generally with several entrances.

Photo credit: National Park Service. Populus deltoides (cottonwood) on the river. It's a brown tree near the shoreline of the river. — Photo credit: National Park Service

Today, beaver are thriving on the upper Mississippi and their impact on floodplain forest trees, particularly cottonwood, in this stretch of river, is not well understood. Studies have found that cottonwood trees have not been successfully reproducing within the Mississippi River floodplain for decades and may ultimately disappear from the upper river corridor. Cottonwoods are an iconic floodplain species whose sturdy branches are a preferred spot for nesting bald eagles, supporting 80% of eagle nests along the river. Cottonwoods also help with bank stability, improve water quality, provide wildlife habitat, store carbon, and filter air pollution. The need to figure out how to restore successful regeneration of cottonwoods is becoming increasingly important.

Photo credit: National Park Service. beaver swimming in Mississippi River — Photo credit: National Park Service

Beaver along the upper Mississippi River have no significant predators, and populations seem to be increasing as a result. Beaver engineer the landscape to create an ecosystem favorable for their own living requirements, similar to what we do as humans. While habitat created by their activities can be beneficial to aquatic and terrestrial wildlife, it can radically change area vegetation. Each year the average beaver family is reported to cut at least a ton of wood within approximately 300 feet of their pond or den.

Photo credit: National Park Service. beaver chew and damage restoration efforts along the Mississippi River — Photo credit: National Park Service

Land managers up and down the river corridor are being challenged by beaver destruction of restoration projects, once saplings grow large enough to provide a good food source. Currently, we don’t know how extensive beaver harvest is on floodplain forest trees or if beaver play a major role in hindering establishment of mature trees along the river. This stretch of the Mississippi stands to lose about half a million trees due to emerald ash borer. Understanding the dynamics between beaver and floodplain forest regeneration is critical to determining how to best manage the floodplain forest so these species can successfully coexist.

The Mississippi National River and Recreation Area and its partners are submitting requests for funding to evaluate beaver impacts on floodplain forest and forest regeneration in this stretch of the river corridor. One of our bio-techs will also be studying beaver populations this summer and may need volunteers to help track beaver activity along shorelines. Sign up for our volunteer newsletter to stay informed of these volunteer opportunities.

What happened to all the trees?