An invasive pasture grass hit a native wetland plant hardest where the hydroperiod was longest

Four years of Camas Prairie monitoring found the invasive grass’s per-unit negative effect on camas survival strengthening in wetter portions of the meadow in some years.

Wild Lands Ecological Intelligence Editor
Wild Lands Institute · 24 September 2026

Evidence: Peer-reviewed
Geography: Camas Prairie Centennial Marsh, south-central Idaho, USA
System: Wet meadow

WHAT THE EVIDENCE SAYS

From 2020–2023, native Camassia quamash had higher survival but generally lower flowering in drier upslope areas. The invasive grass Alopecurus arundinaceus showed stronger negative effects on camas survival in longer-hydroperiod areas in some transitions, while effects on growth and flowering were less consistent.

WHY IT MATTERS / OUR READ

Hydrology can change the strength of an invasion effect within the same wetland. That argues against uniform invasive-plant prescriptions across topographic and hydroperiod zones.

CAVEATS / UNCERTAINTY

Year effects and plot composition could not be fully separated, not every response repeated across transitions, and this is one culturally important wet meadow. Management inferences need local hydrology and Tribal stewardship context.

SOURCE

Wetlands
View original evidence ↗