image: Surveying soil to coordinate important data from national parks, preserves, seashores, monuments and other designations may expand soil science research frontiers due to more logistical challenges like at Lassen Volcanic National Park in Northeastern California. view more
Credit: Soil Science Society of America
In 2010, more than 280 million people visited the lands of the U.S. National Park System, marveling at their deep green forests, red rock canyons, crystalline waterfalls, and vast expanses of blue sky. They embraced the towering coast redwoods, snapped portraits of shaggy Yellowstone bison, and hiked to the foggy tops of the Great Smoky Mountains. It's a safe bet, though, that the majority of these nature enthusiasts never gave a thought to the very land under their feet, to the soils that support the roots of the tallest redwood and nourish the grasses that feed the bison.
Over time, perhaps that will change, as the data from the National Park Service's Soil Resources Inventory make their way into educational materials, park management strategies, and scientific analyses. Since 1999, the program has coordinated data from soil surveys of more than 270 "natural resource units"—a term that refers not only to the national parks, but also national preserves, seashores, monuments, historical parks, and other designations that together comprise the nearly 85 million acres of land under Park Service stewardship.
"Soils are not one of the first things people think of" when they think of the parklands, acknowledges soil inventory program coordinator Pete Biggam. But learning more about the soils can enhance appreciation of the parks for new visitors and longtime park staff alike, he says.
As an example, he cites a visit he made to Glacier National Park in northwest Montana a few years ago. He was walking on a trail at Logan Pass with a Park Service "interpreter," a staff member whose job is to communicate to visitors about the parks in a way that deepens their sense of connection to them. Biggam noticed some pikas—small mammals whose cartoon-mouse faces and enormous ears make them popular with visitors—digging in a yellowish soil, and he joked, "Well, look at that. They're digging in a soil from another national park." At the interpreter's urging, he explained that the distinctive soil was part of the mantle of volcanic ash that blanketed the Pacific Northwest when Mount Mazama erupted, 7,700 years before; the collapsed volcano is now the centerpiece of Oregon's Crater Lake National Park, 700 miles from Glacier.
The interpreter incorporated the story into Glacier's presentations, and a year later, she called Biggam to report that it had an 83% retention rate among surveyed visitors. It made an impact on them, just as it had on her when she first heard it.
In 1999, with factors such as non-native species, recreational uses, and pollution taking a noticeable toll on the national parks, Congress funded the Natural Resource Challenge, which has provided about $12.5 million to date to the Soil Resources Inventory—one of 12 inventory and monitoring programs the Park Service initiated at that time in order to measure and manage its resources more systematically and scientifically. (Other areas of study include geology, vegetation, animal species, and air and water quality.)
Before the program began, some of the smaller parks "may have been mapped as part of a county project," says Biggam, who would then work with his team to incorporate that information into the inventory. But there was no baseline data for the larger parks, which had not been mapped.
Now the Park Service partners with the USDA Natural Resources Conservation Service (NRCS), which conducts all the soil surveys in accordance with the standards of the National Cooperative Soil Survey (NCSS), the long-running nationwide project to inventory and distribute information about U.S. soils. This partnership with the NCSS and NRCS guarantees consistency and comparability across the parks project.
Biggam's team, which includes soil scientists, cartographers, and GIS specialists, takes the survey data and makes it accessible to a broad customer base, creating products ranging from visitor fact sheets and web pages to invitations to other scientists to conduct additional research about a particular intriguing finding.
"We have products that we're developing for geospatial folks," he says. "We also have products for people who aren't GIS specialists, but they need the information and they need to get to it very quickly. So we've developed some customized products so they can just go in and just click on an interactive soil map and up comes the information."
Biggam begins each National Park inventory project with a soil scoping session, generally a year or two before the mapping begins, where park staff can identify management issues and challenges of that particular park and Biggam can try to tailor aspects of the project to address those questions.
"We're designing soil surveys to meet the needs of the park," he says. "So we don't just go knock on NRCS's door and say we'd like a soil survey about Park X."
For instance, the staff of Padre Island National Seashore, off the Texas Gulf Coast, try to balance wetlands conservation with the oil and gas exploration that's allowed there, so it was especially important in that survey to delineate the "hydric" soils, which can support vegetation that grows in flooding or saturated conditions, from the non-hydric soils. The project ended up clarifying subtle differences between the two and mapping far more hydric soils than had been identified in that part of Texas before, Biggam says. Having such data now makes it easier for staff to request that exploration be sited outside a particular area and helps them better prepare for restoration of disturbed lands.
Biggam jokingly compares his role in the inventory program to that of "a soils broker": "I put people who need soils information together with people who can provide it," he says.
While other government agency partners in the NCSS may be interested in what the data indicate about an area's agricultural productivity or suitability for grazing, the Park Service is focused on resource preservation and protection, Biggam says. For that reason, the inventory takes an ecological approach to the physical, biological, and chemical properties of the soils, asking questions such as, What role does this soil play as a habitat for burrowing mammals, insects, and microorganisms?
"Parks are unique areas from which to acquire knowledge about our valuable soil resources," Biggam says, "and they provide a great opportunity to understand the role soils play within nature, while also ensuring that our generation and future generations can learn from them".
It is also focused on scientific discovery. So far, the inventory has identified numerous park endemic soils, including 19 new "species" in Great Smoky Mountains National Park alone—most of those at elevations above 4,600 ft.
Nevada's Great Basin National Park is famous for its bristlecone pines (Pinus longaeva), which can live for thousands of years, making them the longest-lived trees on earth. Prior to the mapping of Great Basin, it was believed that they grew only in calcareous soils—"chalky," alkaline soils, as might be found in an area with a lot of limestone. But the soil survey disproved that.
"We also found others on non-calcareous soils," Biggam says. "We now have more information for scientists to draw on in the future."
The project is also contributing to the science of climate change by identifying the different areas of organic carbon sequestration in the parklands. This helps the park staff, who can now avoiding siting a new visitors' center or parking lot on an area known to be a rich storehouse of carbon from decayed organic matter. Less well understood, Biggam says, is the ecology of inorganic carbon sequestration in crystalline soils with high calcium carbonate content; for this reason, the Park Service is sponsoring research teams in areas of the Southwest with abundant gypsiferous soils, such as New Mexico's White Sands National Monument and Guadalupe Mountains National Park.
And during the survey of Sequoia National Park, in addition to inventorying the soils in the sequoia groves, the project will examine existing soil moisture and temperature regimes and site factors to provide a better understanding over time of the potential effects of climate change on the ancient trees.
There are currently about two dozen survey projects either in the planning stages, being mapped, or compiling their analyses, Biggam says; he expects 15 or so to be completed this year, which would bring the total park units inventoried to around 230 of the targeted 270.
But the units that remain will pose some of the greatest logistical challenges for mappers. They include some of the largest parks, such as 13-million-acre Wrangell–St. Elias in Alaska; the most remote areas, such as the Bering Land Bridge National Preserve, accessible in summer only by boat or small plane; and parks with particularly tricky topography, such as the subtropical Everglades, and Death Valley, the hottest and driest desert in North America.
Biggam regards these landscapes as great opportunities to expand the frontiers of soil science. "We're always open to new tools and techniques in the mapping of our lands," he says. "We also provide 'test beds,'" to university researchers or other teams with ideas that they want to try out and evaluate.
He cites as an example the GIS-based Remote Area Soil Proxy (RASP), developed by the team that mapped mountainous North Cascades National Park in Washington State in 2004. For areas that are so remote that extensive fieldwork there may be hazardous or prohibitively expensive, scientists wonder, "Can we gather information without being there?" he says. Using RASP, scientists can generate a predictive map of an area's soils by utilizing various geospatial data sets about such soil-forming factors as the area's vegetation, elevation, aspect, parent material, and climate into the program. Those data are then incorporated into computer models of how different soils are formed under varying conditions and processes to create the map.
"We know that when we go into an area like the Everglades"—with vast swamplands filled with rare, and sometimes dangerous, species—"we need to widen our toolbox, and take a look at what existing or new technologies may be applicable to help us," Biggam says. "We may not use it wall to wall, but we may use it to help us out, and then, if we can evaluate it, we can let science know what worked and what didn't."