Upper Red Rock Lake has been filling in with silt. Some estimates are that it will fill in completely within 50 years. Conservancy interns have examined key streams that feed into the lake, with the goal of finding out how much of the sediment coming into the lake is from natural sources and how much is human-caused.

Wetlands are a dominant feature of the Centennial Valley and the centerpiece of the Red Rock Lakes National Wildlife Refuge.

Conservancy interns have worked with the Fish and Wildlife Service’s Partners for Wildlife Program to plant willows along the Red Rock River.

Some of the limber pines in the Centennial Mountains may be older than 600 years, according to the Montana Natural Heritage Program. Those trees are found in higher elevations on public land.

But what about the mid-elevation forests on private lands, which are important areas for wildlife?

Conservancy interns, armed with tree core borers, tape measures, and other tools, have studied tree rings and measured tree width. They've found Douglas firs they estimatesare 200 to 300 years old. The studies also tell what disturbances these giants have weathered during their history, disturbances such as insect outbreaks, diseases, drought and fire.

Tree cores show that major fires occurred in 1930, 1872, 1840, 1790, and 1743. This means that parts of the forest burn on average every 47 years, though nothing is known about the size and intensity of these burns.

This history poses some interesting questions for the Centennial. Is the area due for a major fire? How intensively will the next fire burn given that the forest has not had a wildfire in over 70 years?

The Centennial Sandhills, just north of Red Rock Lakes, are one of only two sandhill areas in Montana. These sandy dunes support several sensitive plant species.

Research by the Montana Natural Heritage Program and a Conservancy botanist in the 1990s found that these plant species are "pioneers," meaning they only occur where sand dunes are exposed and actively moving. Ironically, these species are slowly disappearing from the sandhills as they become more vegetated.

"While we’re concerned about excessive soil movement and siltation along the Red Rock River, we want to encourage stewardship that maintains the natural mosaic from stabilized to active dunes in the sandhills," says Brian Martin, a Conservancy’s science and stewardship director.

Active management with cattle can sustain the diversity of habitats needed and is one of the focus points in the Conservancy’s efforts with private lands in the sandhills.