Cheatgrass will migrate with climate change

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Climate change will help some of the West’s most troublesome invasive plants conquer new territory, but the pesky invaders will also retreat from some currently infested areas.

A new study published in the journal Global Change Biology predicts that yellow starthistle, an unpalatable rangeland invader established in much of California, will march across even more of the state and Nevada.

Cheatgrass, a highly flammable annual grass from Eurasia that blankets much of the Great Basin, will probably spread north into more of Idaho and parts of Montana and Wyoming but retreat from central and southern Nevada and central Utah.

Princeton University researchers examined 10 climate models and arrived at a ‘best guess’ of how changes in such factors as seasonal and annual precipitation over the next century could affect the distribution of five prominent invasive plants.

Tamarisk, a shrubby tree that grows along streams and sucks up water, will probably be unaffected by climate change. Leafy spurge, abundant in northern states west of the Mississippi, will probably retreat in Colorado and parts of Idaho and Oregon.

Spotted knapweed, which grows in the foothills of the Rocky Mountains and on the Colorado Plateau, is expected to move to higher elevations.

‘We’re not talking about a wholesale retreat of invasives,’ said the study’s lead author, biogeographer Bethany Bradley.

Instead, it will be more of a rearrangement of the invaders, providing some chances for ecological restoration.

But a changing climate will also affect native plants. Even if invasives die out, the researchers said, native growth that historically occupied an area may not be able to reestablish itself. Instead, other types of native plants suited to the new climate may move in. Or other invaders may take hold. For example, red brome, an exotic found in the Mojave Desert, could take over former cheatgrass lands.

— Bettina Boxall