College of Forestry - Oregon State University

Features
Pretty but Perilous: Protecting Forests and Meadows from
Weedy Interlopers
O thou weed! Who art so lovely fair and smell’st so sweet that the sense aches at thee, would thou hadst ne’er
been born.—William Shakespeare, Othello
To the casual observer, a patch of sulfur
cinquefoil is a beautiful meadow sunlit with
flowers. But to a weed specialist like Steve
Radosevich, Professor of Forest Science, it’s
a field overrun by a pernicious weed that
threatens native plants and forage.
The cinquefoil, known more formally as Potentilla
recta, is one of 109 invasive nonnative species in the
Pacific Northwest. Cinquefoil
thrives in forest meadows,
old pastures, and other sunny
disturbed areas; it also grows on
rangelands and in open forest
stands. It spreads easily, but its
principal threat is its competitive
ability. As it gobbles up space
and nutrients, it threatens native
plant communities, diminishes
plant diversity, and decreases
food supplies for wildlife.
Invasive plants were formerly
known as weeds, and their
relationship to forest regeneration
and sustainability has captured
Radosevich’s attention for
some 30 years. When he started
out, weeds were controlled
primarily by herbicide spraying
and burning. His experience has
convinced him that new, more
lasting approaches to control are needed. “Over the years,
good biological and ecological studies pay off more than
herbicide spraying trials,” says Radosevich. “Herbicides
are like medicine; if you need them short-term, use them;
but long-term, get healthy, and you won’t need them.”
Herbicides are like medicine in another respect: repeated
applications are expensive. Finding ways to avoid them
would save land managers money.
For Radosevich, his Research Associate Bryan
Endress, and their collaborators, control of the sulfur
cinquefoil and other invasive species presents a continuing
challenge and requires innovative approaches.
Their research program is centered in the Blue Mountain
Ecoregion, the primary habitat of the cinquefoil in
Oregon. Their many-pronged study assesses habitat risk,
projects spread of the species, and examines its biology,
competitive ability, and strategies for containment. In
one approach to control, the group is setting up experiments
to determine the ability of native cinquefoils and
grasses to compete against the invasive species. In other
studies, they are examining the dependence of P. recta
and native cinquefoils on insect pollinators and whether
grazing by cattle, deer, or elk affects cinquefoil success.
Although the cinquefoil is their test species, the
models and control methods that Radosevich, Endress,
and their collaborators develop from the data will
provide the basis and framework for a regional research
program that will enhance understanding of the basic
biology and demography of many invasive plants. Shared
with managers and other researchers, this understanding
will lead in turn to development of effective strategies for
adaptive management and habitat restoration.
“We need multiple strategies of control and intervention,”
Radosevich points out. “We’ve been looking at
separate pieces; now we’re able to look at the problem
holistically.” A holistic approach requires many collaborators.
Their primary collaborators
include Catherine
Parks and other USDA
Forest Service scientists, as
well as scientists from the
Oregon Department of Forestry
and Department of Fish
and Wildlife, the Umatilla and
Wallowa-Whitman National Forests,
and the Nature Conservancy.
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