A nature preserve in St. George created to help save rare animals and plants has expanded by 161 acres through the sale of school trust land to the conservation group developing the ongoing project.

Michelle McConkie, a lawyer for the School and Institutional Trust Lands Administration, said the Nature Conservancy paid $535,000 for the parcel, the third addition to the White Dome Nature Preserve since 2005.

The area of pale, usually barren soil, sits within the St. George city limits where it abuts the Arizona state line. The preserve was created to help protect the dwarf bear poppy, an endangered species that produces numerous white flowers in the spring, and the threatened Siler's pincushion, which also grows in a small area in Arizona.

Money from the land sale goes into the Permanent School Fund, a perpetual endowment that annually distributes income to each K-12 public school in Utah.

McConkie said the land purchase is a win for the state's schools while helping to preserve rare plants and animals such as the zebra-tailed lizard and loggerhead shrike in what is envisioned as an 800-acre preserve. The Utah Department of Transportation has also contributed 140 acres to the site.

A fourth land purchase of several hundred acres for the preserve is in the works, said McConkie, and the conservancy is under contract to purchase 6.4 acres of trust lands outside the preserve and east of Interstate 15 for $206,000 to protect the

Elaine York, west desert regional director for the Nature Conservancy, said Wednesday the preserve is the only location in the world with the necessary geologic formations -- including gypsum-rich soil -- that satisfies the strict demands of the rare plants.

Plans to build a series of trails and educational signs throughout the preserve are under consideration.

"We're working with the U.S. Fish and Wildlife [Service] and a botanist to see if the area's compatible to connect people to the plants," she said.

York said similar cooperative efforts a decade ago helped create the Red Cliffs Desert Reserve in St. George to protect the desert tortoise.