Sentinel wetlands at Cuyahoga Valley National Park: condition, threats and restoration

Ohio has lost 90 percent of its original wetlands, and Cuyahoga Valley National Park has more than 1,500 still within its boundary. The National Park Service's Heartland Inventory and Monitoring Network watches the condition of some of them closely. Its findings: most monitored plots held steady or improved a little, mitigation wetlands score low, and invasive plants are the most widespread and most controllable threat.

Oxbow Pond at Beaver Marsh, Cuyahoga Valley National Park, Ohio. NPS.

Why wetlands are watched

Wetland soils stay soaked long after heavy rain or when groundwater sits near the surface, so wetland plants differ from those around them. Wetlands shelter thousands of plant and animal species, including, the Park Service says, nearly half of all U.S. endangered species, and they protect water quality, reduce erosion and help control floods. Invasive plants, extra storm water from development, drainage ditches and other disturbances change how they work.

Sentinel wetlands monitored at Cuyahoga Valley National Park. NPS.

The sentinel wetlands

Scientists monitor a set of important wetlands intensively. Some are reference wetlands, among the highest-quality and least disturbed in the park: Boston Mills, Langes, Kendall Lake, Columbia Run, Stumpy Basin, Snowville, Bath and Fitzwater. Others are of concern to park managers, in three kinds:

What is measured

Staff record the land uses around each site and assess size, vegetation, hydrology and condition. In 37 permanent plots they record the cover of every plant species and the density of woody plants, measuring the stem of any woody plant over 3 feet tall. These data feed scores for each wetland's health, such as the share of sensitive plant species, the share of invasive grasses and species richness, and the higher the score the better the condition. Initial surveys were done between 2008 and 2015, and all plots were resurveyed in 2018.

Monitoring at the Krejci wetlands. NPS.

What the surveys found

• Boston Mills, Kendall Lake, Stumpy Basin, Columbia and Beaver Marsh are in excellent condition in one or more plots, with specialized plants. Fawn Pond is good at most plots and scores very high among its class, riverine mainstem wetlands.
• Proposed restoration at the Pleasant Valley complex and Fawn Pond should be re-evaluated, because both have extensive invasive plant communities. A stream restoration at Stanford Run was completed in 2020 and its changes are being documented.
• Mitigation wetlands score low. Brookside Marsh and Rockside Marsh no longer meet the benchmarks set by the U.S. Army Corps of Engineers and the Ohio Environmental Protection Agency. Krejci is young, so its success is still unknown, though the short-term outlook is good.
• In the 2018 resurvey, condition stayed the same or improved slightly in 25 of the 37 plots. Invasive grasses such as cattail, common reed and reed canary grass covered more than a quarter of the sampled area in 11 plots and increased in 18. In eight plots, at Rockside Marsh, Beaver Marsh, Fawn Pond, Brookside Marsh, Stumpy Basin and Pleasant Valley, they rose by more than 10 percent.

Invasive plants seem the most widespread threat and also the most controllable. Sensitive species turn up even in the lowest-scoring wetlands, so controlling invasives could bring native plants back quickly.

Erosion and incidental filling at Stumpy Basin wetland. NPS.

What is being done

The Nature Conservancy has a grant to restore nearly 600 acres of wetlands in the Cuyahoga River Area of Concern from 2024 to 2027, treating invasive species that threaten wetland bird habitat, nesting and foraging. The work focuses on large wetland complexes and park sentinel sites, including Beaver Marsh, Stumpy Basin, Krejci, Kendall Lake, Brookside Marsh and Rockside Marsh, so monitoring before and after will show which practices work.

The dump behind Krejci

Krejci's wetlands, built in 2012 as mitigation, answer to the Krejci Dump, an industrial waste salvage yard that operated from 1948 to 1980. The Park Service acquired it in 1985, and cleanup ran from 1987 to 2011.

Krejci Dump, 1981. NPS.

The Krejci wetlands are a mosaic of seven marshes and wet meadows in upland prairie. The deeper marshes catch runoff from higher in the watershed, and water cascades down to the shallower wet meadows before draining west into three streams. Monitoring shows good plant community and habitat development, which scientists expect to improve if invasive species are controlled.

Sources

• National Park Service, Heartland Inventory and Monitoring Network, Sentinel Wetlands Monitoring at Cuyahoga Valley National Park; the source says 20 sentinel wetlands but names fewer, so the count is left out; rewritten in hubnx's own words.