Monday, July 25, 2011

Researcher Finds New Threat to Rare Plant

Slickspot peppergrass knows what it likes. When it comes to a place to live, this plant is hard to please. The small white spring flower likes southwestern Idaho: it grows nowhere else. The plant, which is not actually a grass, only grows on certain soils in this area. Even on those soils, you’ll have to look carefully to find this peppergrass: it only grows in slickspots: small depressions that hold water longer into the hot, dry summer than the surrounding soil.

You might expect the plant to keep a low profile, hunkered down in the slickspots of the sagebrush desert. You’d be wrong; this unassuming plant has been argued over and published on, counted and studied, dragged into federal court and scrutinized by the state of Idaho.

Foes of livestock grazing point to their favorite target as the cause of the rare plant’s low numbers. Ranchers point to the data, which don’t link cattle activity and plant numbers. Researchers point out that the annual data only give once-a-year snapshots of the plants, which reveal little about what they need to thrive.

In the midst the controversy, Ian Robertson discovered a new threat to slickspot peppergrass: industrious ants. Robertson, an entomologist at Boise State University, studies insect pollinators of the plant, which spreads only by seeds. While looking at pollinators, he noticed something else: ants were carrying off and eating the plants’ seeds.

In addition to recognizing a new threat to slickspot peppergrass, Robertson’s work also solved the mystery behind a well-known pattern. He identified ants as the link between the loss of native vegetation after fires and the decline in the peppergrass.

I wrote about these new findings for the Boise State Division of Research and Economic Development.