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Repairing Sheldon’s Prairie

Using investigative techniques, one park rebuilds its grasslands and wetlands with historical accuracy.


From the top of the John Jacob Observation Tower at Sheldon Lake State Park, Andrew Sipocz points out downtown Houston in one direction, the San Jacinto Monument in another and the park’s recovering grasslands below. The view from above has been a key component in Sipocz’s groundbreaking work in restoring the prairie and wetlands in the park — the type of coastal prairie that used to stretch as far as the eye could see.

Less than 1 percent of Texas’ coastal prairie remains, most of it gobbled up by rice farms and cattle pastures, Astrodomes and Gallerias. Sipocz, a natural resources coordinator for the Texas Parks and Wildlife Department, has been on a mission for 20 years to hold on to a piece of it — to rebuild it, really — here at Sheldon Lake.

Instead of following the usual template for wetland restoration, Sipocz came up with his own method that pulls from history, archeology and biology — poring over 1930s aerial photographs to find where wetlands had existed before and re-excavating them. By investigating the landscape history and following nature’s patterns, he’s been re-creating the historical prairie and wetland complex as accurately as possible.

“I can't think of any other landscape in the world that has been erased more extensively than the Texas coastal prairie,” Sipocz says. “When that happened, it was downfall of a whole lot of wildlife and plants. I wanted to restore a piece of that landscape here.”

Sheldon Lake_1873

Front door of the park

The latest piece of Sheldon Lake restoration has been taking place over the past few years on a 100-acre plot right at the entrance to the state park, where visitors take the turn off Garrett Road in northeast Houston.

The park has restored 400 acres since 2003, and the 100-acre entrance plot brings the restoration total to 500 acres.

What had been a flat-as-a-pancake St. Augustine sod farm at the entrance is now a lush coastal prairie, with slight rises for the uplands and depressions for the wetlands. Seven wetland ponds were excavated and planted in 2017, and the prairie was seeded in August 2020.

Waist-high prairie grasses wave in the breeze. Frogs croak in the ponds, and an alligator lurks in the marsh. Red-winged blackbirds fly from perch to perch. A yellow-crowned night heron hides in the tall grass. It’s a remarkable transformation from what was basically a 100-acre lawn.

Prairies are one of America’s most endangered ecosystems, and one of its most complicated and diverse.

“We’re trying to restore this to what was here historically because we think that will give us the best results at recovering this vanishing ecosystem,” says park Superintendent Kelley Parker. “It’s all planted. Now we sit and wait.”

Actually, Parker and natural resources specialist Matthew Moore rarely do much sitting. The restoration work requires monitoring, planting, removing invasives, burning and mowing. Plus, they have their traditional park duties — hosting school groups, leading nature walks and more. Sheldon Lake State Park and Environmental Learning Center is a 2,800-acre nature preserve specializing in the introduction of urban youth to the outdoors.

“This is the front door to the park,” Parker says. “We’re really giving folks a chance to see our work. They can see the sun glistening off the ponds. They’re getting to see all the wildlife.”

 Courtesy texas coastal watershed program

To find the original wetlands, TPWD's Andrew Sipocz used comparative photos to identify features such as a road and canal (denoted by arrows). The 1995 photo reflects the difficulty in finding original wetland boundaries. The 1930 photo shows the wetlands and sandy uplands, called mima mounds.

The Sipocz method

When land is converted to agriculture — much of the state park property was inundated by the lake before becoming a rice farm — it is carved up and basically leveled. The wetlands are filled in and the uplands are removed so that the fields can be easily flooded for rice.

“The coastal prairie of Texas was not all flat to begin with,” Sipocz says. “It had a lot of topography. It was dotted with ponds and sandy ridges and knolls.”

The restoration work at Sheldon
Lake is bringing back that pond-filled tallgrass prairie.

Traditionally, wetlands restoration projects have involved digging a depression or pond without too much regard for soil types or historical wetlands, and without regard for surrounding prairie. A levee might be built to hold the water. Many of these wetlands are managed to attract large amounts of waterfowl.

Sipocz’s method takes a more scientific, historical, holistic and surgical approach.

It’s a little bit Sherlock Holmes and a little bit CSI: Houston. Aerial photos from the 1930s have guided much of his work. By looking at black and gray and white patterns in the photos, he found historical wetlands and uplands, matched them to the current landscape and created a template for restoration.

He collected 1920s topographic maps and color infrared photos from the 1990s to precisely determine wetland depth zones and to distinguish wetland brush from upland brush. Photo signatures of old upland mounds, irrigation canals and pipelines helped confirm the alignment of the photographs.

Sipocz then dug soil samples to find the true boundaries of the original basins, looking for distinguishing soil signatures such as the thick clay that formed the bottoms of the wetlands.

That way, he knew exactly where the wetlands existed and how deep to dig. The park brought in equipment to precisely excavate the wetlands according to geo­referenced coordinates and expose the original soils at depths that varied across each basin.

After the basins were excavated, staff and volunteers planted the areas with native vegetation and seeded them with seeds harvested from prairie remnants.

Sheldon Lake’s volunteers maintain nurseries of prairie plants and wetland plants for use in the park. The park relies on its corps of volunteers, some from the Gulf Coast Master Naturalists, to collect seeds, propagate plants, remove invasives and help with plantings. To date, volunteers have planted more than 140,000 native prairie plants.

In the restoration, the marsh basins are planted with water-loving vegetation such as sedges, rushes, arrowheads and lilies, while the marsh edges contain transitional grasses such as gamagrass and switchgrass. The drier prairie uplands are dominated by bluestem, Indiangrass and other species.

“What I’m trying to do, as best as I can, is re-create all these microhabitats that the different plant and animal species use,” Sipocz says. “I want to have the greatest amount of plant and wildlife and bird diversity.”

The result is a mosaic of uplands and wetlands that interact with each other and support dragonflies, turtles, grassland birds, bobcats and more.

“It’s really a complex landscape,” he says. “You have deep sandy soils, and you have wet clay soils. You have acidic soils, and you have alkaline soils. The wet areas and dry area have very distinct vegetative communities. The total elevation difference between the top of those high spots and the low marshes is only about five feet, but the difference in the plant communities is absolute.”

The diversity of soils leads to a diversity of plants. The diversity of plants leads to a diversity of insects. The diversity of insects leads to diversity of other wildlife. And on it goes.

What’s one measure of success?

Secretive marsh birds. Birds such as rails and bitterns thrive in habitats with a good mixture of wetlands and grasslands, where they can hide, and they’re increasingly at risk to the loss of coastal prairie.

“We get American bitterns and least bitterns,” Sipocz says. “We get king rails and sora rails, yellow rails. I’m not seeing black rails — that would be the Holy Grail.”

Woody Woodrow of the U.S. Fish and Wildlife Service has worked with Sheldon Lake and appreciates the state park’s restoration success.

“What’s really valuable about that is its holistic approach,” he says. “It’s not just focused on wetlands, and it’s not just focused on the prairie grasslands. It’s looking at it holistically and saying, hey, you know, they exist together. They are restoring that historic template of what was on the landscape. I’ve never seen it anywhere better than the work that they did at Sheldon Lake.”

Let It Burn

Prairies lack the drama of a forest or mountain. They’re more like an iceberg, with much of the action happening below the surface. Up to 75 percent of a prairie’s biomass is underground. Fibrous roots spread out and descend as much as 15 feet into the ground; those roots contain billions of microscopic rootlets. By existing mostly underground, prairie plants can survive grazing, drought, fire and frost.

Sipocz points out a gayfeather, a common prairie wildflower.

“This has beautiful purple flowers on it later in the year,” he says. “If you dig down, it has these big bulbs. And it just sprouts right up after it burns.”

To many people, fire is destructive. To Sipocz and Parker, it’s transformative. Fire is one of the secrets to prairie health, and Sheldon Lake conducts regular prescribed burns to mimic historical prairie fires.

“Fire is the closest thing we have to a magic wand,” Sipocz says.

Fire kills trees and encroaching woody plants, giving grasses more sunlight. It warms the soil and removes old, dead vegetation. It helps speed up decomposition to add nutrients to the soil.

Parker and Sipocz say that Sheldon Lake had one of its most successful fires in fall 2020 when it burned 300 acres in the main part of the park.

“We ran a fire through here, and look at what pops up,” Sipocz says, kneeling to get a closer look at the plants. “This is native coreopsis. This is Indian plantain behind you. This is meadow pink. All these are native prairie plants that have just been kind of hanging out in the shade waiting until they got some sunlight to come up. We didn’t plant any of this. It’s always been here.”

The Big Picture

Sipocz, in addition to looking from above, looks back. He sees this land in geologic time, with a deep understanding of what it was so he can imagine what it still can be.

The coastal prairie around Houston was shaped over millions of years by wind and water. The Texas coastal plain is basically a series of overlapping river deltas as meandering rivers flooded, changed course and dropped layer after layer of sediment. As ice ages came and went, rivers alternated between carving valleys (such as Galveston Bay) and building up deltas. The prairie and wetlands at Sheldon Lake and the Houston area grew out of this, becoming tallgrass prairie dotted with tens of thousands of marsh ponds, remnants of ancient rivers.

Rains filled up the basins, providing much-needed water for frogs, insects, plants and migratory birds. When the ponds dried out, the winds came through and blew soil out of the basins, forming small dunes called mima mounds.

Re-creating a landscape formed over such long period of time is not for the faint of heart. Some aspects are definitely more difficult than others.

“The wetlands are the easy part,” Sipocz says. “The hard part is the prairie. It takes a long time for prairie to come back.”

Unfortunately, unlike those prescribed burns, there is no magic wand for the rest of Texas’ coastal prairie.

The coastal prairie is important not just for Houston’s history but for its future as well. The prairie and wetlands provide vital habitat for native species, absorb floodwaters, filter surface water and recharge groundwater systems.

With 99 percent of it gone, the remaining pieces like the one at Sheldon Lake become that much more important.

Russell Roe is the managing editor of Texas Parks & Wildlife magazine.

Helping the Park

Sheldon Lake State Park couldn’t accomplish all this without its volunteers and partners. “The volunteers are such an integral part of the restoration efforts at the park,” says Superintendent Kelley Parker. “Without their constant passion and continued efforts, we would not have been able to complete a fraction of the restoration that has been done.” Funding for the latest phase of restoration was provided by Harris County, the U.S. Fish and Wildlife Service and Ducks Unlimited, with labor provided by University of Houston–Clear Lake and Texas Agrilife.

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