7 Year Wetlands Tree Study

Virginia Institute of Marine Science Researches Restoring Forested Wetlands

A trio of citizen scientists armed with measuring tools moved from one tree to the next to the next — from black willow to sycamore to white oak.

First, they made sure the specimen was still living. Then they noted its species, spread measuring tape under the width of its canopy, and pinched calipers around its stem at ground and chest levels to take its diameter.

It's a process volunteers will repeat more than 1,200 times this week and next, taking about 30,000 numbers in all, as part of a seven-year field experiment intended to help restore vulnerable forested wetlands.

"They're one of the most heavily impacted wetland systems probably in Virginia, and probably the whole mid-Atlantic," said Herman W. "Wes" Hudson III, who's heading up the research as part of his doctoral work at the Virginia Institute of Marine Science (VIMS) in Gloucester Point.

There are various types of wetlands, but forested headwater wetlands and their associated small streams represent a larger percentage of the state's waterways, Hudson said. They're also the wetlands most likely to be impacted by man — they're drier, don't lie in deep water, and are sited where streams are small so they're easier to log or convert to agriculture.

In colonial times, wetlands covered nearly 1.8 million acres in Virginia, or more than 7 percent of the state, according to the Virginia Department of Environmental Quality (DEQ). For many years, they were considered mucky, foul, dismal places in need of draining and reclaiming.

By the 1980s, when permits began to be required for most impacts to wetlands, about 42 percent of Virginia's wetlands were gone, largely because of human development.

But since 2000, the net loss of wetlands has slowed because of stricter laws and enforcement and new mitigation strategies — including a commitment by the state to increase its net acreage of wetlands throughout the Chesapeake Bay watershed, in part through restoration.

Hudson's research is one way to determine the best way to reach that goal.

Six years ago, he and others planted 2,772 trees equally among three acres leased at the New Kent Forestry Center. They chose seven species — river birch, sweetgum, sycamore, black willow, swamp white oak, pin oak and willow oak — and planted them at different levels of growth: bare root, tubeling (young seedling) and 1-gallon container.

The three acres were then given different soil and water conditions. An ambient acre had the least stressful conditions, a saturated acre was given more water stress, and a flooded acre was stressed not only with water but with poor soil conditions.

Today, the ambient acre is a veritable young forest, with some trees thrusting as high as 40 feet. On the saturated acre, river birch, sycamore, sweetgum and black willow — considered primary or early-succession species — are thriving, hampering the growth of the later-succession species of oaks. And on the flooded acre, only a handful of stunted trees have survived on a plot overtaken by herbaceous plants and grasses.

What's significant in their findings, Hudson said, is how important it is when doing wetland restoration to follow the natural trajectory of successive growth. To plant species that are better suited to watery or stressed conditions, and thus can lay the groundwork for successive species. The result is a restored wetland better able to survive — and help humans survive, as well.

"Wetlands provide lots of ecological functions to the landscape that are important for our surrounding ecosystems, such as the Chesapeake Bay," Hudson said. "But they're also important to humans, such as cleaning our groundwater for drinking. They protect us from floods and they also help remove excess pollutants or nutrients before they enter the waterway."

Source: Daily Press

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