Who Needs Rainforests? We have Riverscour Grasslands in our Backyard… Kinda

Riverscour grassland along the Caney Fork River, White Co., TN - Southeastern Grasslands Institute

Who Needs Rainforests? We have Riverscour Grasslands in our Backyard… Kinda

Obviously, there are several questions you probably immediately had after reading the title of this blog; the first being, “what the heck even is a riverscour grassland?” And the second is wondering why any self-respecting environmentalist is dissing rainforests.

First of all, I am an environmental geoscientist, but self-respecting is ambiguous, and I’m not really dissing rainforests, just bringing some attention to a more local source of biodiversity: riverscours, which are a really cool type of grassland that form on high gradient, or steep sloped, streams and rivers. There are riverscour grasslands scattered all across the southeastern U.S., in states like Arkansas, Alabama, Georgia, Indiana, Kentucky, Tennessee, and Virginia.

Riverscour on Big South Fork Creek, TN - Southeastern Grasslands Institute

Green pitcher plant in Alabama Riverscour - Alan Cressler via SGI

What makes riverscours unique from other grasslands is the type of disturbance they depend on. While typical grasslands rely on fire or grazing to maintain their health, riverscours depend on semi-frequent flood events to prevent large, woody vegetation from forming. Riverscours also require stable bedrock and cobble streams that can withstand frequent flood events, while maintaining relative stability and an open canopy. The relative stability in riverscours over long periods of time has led to a large number of endemic, only native to riverscours, plant species. These ecosystems are small and isolated, and on average are only around the size of a football field. Even though riverscours are small, they are extremely biodiverse. For example, in the Cumberland Plateau in Tennessee, riverscour take up less than 1% of the total land area but contribute 25% of the region’s plant species. Researchers of riverscours are still finding and categorizing different species every time they study a new riverscour.

While you have almost certainly heard of the threats to rainforests, it is unlikely you have heard of the threats our grasslands are facing, even though grasslands are much closer geographically.

Limestone Riverscour, Clarksville, TN - Dwayne Estes via SGI

Grasslands, and in particular, riverscour grasslands, face the same threats rainforests do. Climate change, dam construction, hydrologic alteration, invasive species, and deforestation are all extremely detrimental to the health and stability of grasslands.

Total Historic Range of SE U.S. Grasslands via SGI

Going back to pre-European colonization, the southeastern U.S. has lost 90% of its total grasslands. But as we’ve established, most of the world has no idea what a riverscour grassland is, and this includes many scientists.

Daddy's Creek Riverscour Cumberland Count, TN via Dwayne Estes - SGI

There are organizations such as the Southeast Grasslands Institute that is actively researching riverscours and attempting to protect and preserve all grasslands. And while yes, rainforests are really important and deserve to be protected, so do riverscours. The first step in protecting these awesome ecosystems is to bring awareness to them, so just try and keep riverscour grasslands in mind the next time you think about endangered ecosystems, and we can work on protecting our little slice of amazonian biodiversity we have here in the SE U.S.

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