Meet Oregon’s Invasive Species

When you think of an invasive plant, what is the first image that comes to mind?  Something ugly and creeping?  A mat of kudzu, or perhaps the painful spikes of a thistle?  In a cruel twist of fate, two of the most infamous invasive plants in Oregon are a pretty yellow flower and a delicious fruit.  Scotch broom and Himalayan blackberry were introduced here as a garden ornamental and a berry crop, and have rapidly spread across the state.  Now their presence is so visible, even the local fifth graders have taken notice.

(A logging road overrun with scotch broom on either side.)

A few weeks ago, I ran a short workshop on invasive plants for Douglas County fifth-grade students.  My time was short, as was their collective attention span, so I gave a simple crash course in invasion ecology.  Non-native plants become invasive when they disrupt the natural functions and processes of native ecosystems.  They often thrive in disturbed habitats and out-compete all other species.  These invasive species need to be managed to maintain healthy levels of biodiversity in an ecosystem.  I was gratified to see nods of understanding, and I came to realize how familiar these students already were with Oregon’s invasive plants.  I heard countless stories of yards bursting with blackberries or roadsides lined with scotch broom.  These kids did not need to use their imaginations to picture the dramatic effect that invasive species have in reshaping ecosystems, because they see it happening every day.

The most common ways to manage scotch broom and blackberry are to manually remove them, spray them with herbicide, or use the cut stump method.  In this last treatment, the plant is cut down to the stump, which is then sprayed with herbicide.  Unfortunately, I do not have a pesticide applicator’s license yet, so my part in these management efforts has been less direct.  For the past three weeks, I have been visiting recently disturbed or soon-to-be disturbed sites and mapping the location of scotch broom, blackberry, and a few other invasive plants.

(Mapping a patch of Himalayan blackberry in aftermath of the Horse Prairie wildfire, which occurred in August of 2017.)

After all, to manage an invasive species, you first have to know where it is.  In addition, mapping the location of an invasive plants over time is a good way to measure the success of various management strategies.  Toward this end, I have been recording the location of our invasive plant targets at two different sites: a road system that will soon be used as a timber haul route, and a large area of land that burned in a wildfire last year.  I was sent to these sites because disturbed habitat is normally a stimulus for the establishment and spread of invasive species, so there is a special need to monitor these areas and target them for herbicide treatment.

(Disturbed ecosystems, like this forest after a large wildfire, are prime habitat for invasive species.)

Managing invasive species often feels like an uphill climb.  An extremely steep one.  Time and resources are limited, and the spread of invasive plants is not an especially charismatic topic to rally around.  But at least I can do my part, in mapping these plants, to contribute to the continued health and integrity of Oregon’s native ecosystems.  Perhaps someday there will be a Douglas County fifth-grader who has never even seen a non-native blackberry.

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