Invasion of the Invasive

The introduction of non-native, invasive plant and animal species on Eugene lands has had growing environmental and financial effects. Invasion by exotic species is second only to direct destruction of biodiversity. Not only do non-native invasives takeover space needed for native plants, but at times the non-native plants replace the natives which affects other native species that rely on them. This can lead to the disappearance of native species, termed “extirpation,” and can further impact species higher on the pyramid of the food chain. Before we dive deeper in the invasive species discussion, let me clarify that only a small subset of exotic species are invasive.

The vast majority of the invasive in the Eugene area were deliberately introduced for landscaping and other uses. These species separate from cultivation and may spread like a plague causing massive damage to natural biotic populations. In result, exotic species are a major causal factor leading to many local extinctions of native plants and animals. In addition, several invasives clog waterways, downgrade recreational and agricultural areas, reduce land values, and some are poisonous to people and/or livestock.

Every year the City of Eugene has progressively prioritized the restoration and renovation of delicate habitat locations including the Wes Eugene Wetlands, Hendricks Park Forest, Whilamut Natural Area of Alton Baker Park, Ridgeline Trail, and Spencer and Skinner buttes. However, the invasion of invasive species is winning the war. They are frequently found out-competing our native species threatening food, habitat and genetic diversity of plants and wildlife. In 2003, the City propelled a new policy prohibiting the use of the most problematic and documented invasive species, discouraging the planting of other species that are suspected to be problematic, and encourages the use of native plants on all City owned property and projects (Invasive). Next, I would like to discuss a few invasive plants and animals flourishing in the Eugene territory.

Yellow flag iris may have beauty on its side, but it impairs Eugene native-species greatly. It is a garden escape from Europe and it was first recognized as having ranged to natural areas in 1911 (Simpson). Once the yellow iris makes it claim to an area it colonizes in large quantities, developing single specie stands that out compete native wetland plants. The yellow iris grows quickly and aggressively and produces bright yellow flowers when in full bloom which wins over much of the general public. They can sprout as tall at 5 feet in height and are very dominant. Not only does the yellow iris takeover native species, it is poisonous to most animals, especially grazing animals, including humans. “The symptoms of yellow iris poisoning include, but are not limited to, gastroenteritis, stomach pain, nausea, vomiting, diarrhea, muscle spasms, and even paralysis in severe cases (Invasive). In Eugene, the yellow iris has established itself in Bertelsen Slough, Amazon Creek, other west Eugene wetland areas, and now is regular along the Willamette River.

The next invasive species I would to discuss is widely spread throughout the Pacific Northwest, the Himalayan and Evergreen Blackberry. Populations are well established in all plant communities throughout Eugene. Originally presented for fruit, blackberries are naturalized, widespread and corrupt native species. They are easy to pin-point by their overwhelming sized thickets and sharp spines protecting the stems. The blackberry bushes can grow in size of 15 feet tall, canes can reach 40 feet long, and depending on the season they can be covered with delicious blackberries. The invasive blackberry species devour native undergrowth and reduces native tree establishment that require sun for germination, such as the Pacific Madrona, Douglas Fir and Western White Pine (Noxious). Also, blackberry vegetation can impede on pathways to water and other resources for larger wildlife, not to mention causing problems for humans attempting to enjoy the great outdoors.

Like many Pacific Northwest residents, I have had large amounts of exposure to blackberry bushes so I would like to share my own personal opinion of them. Personally, I have a love-hate relationship with them and I think many people would concur. My childhood home was surrounded with blackberry bushes outside of our landscaped property. During late summer, the blackberries ripen and my love for them goes through the roof. I used to pick blackberries nearly every summer day and make pies, milkshakes, muffins, scone, etc... My dog would even pick and eat them right off of the thorny bushes. However, outside of summer, blackberry bushes are pestering. When I was younger there was countless times where I would return home with scratches all over my body from playing in the forest. We had trails throughout the forest we lived near and many times the trails were overrun my blackberry bushes and we had to spray and cut them down to regain a useable trail. Throughout my life I have spent numerous days fighting blackberry bushes, but I still seem to have a sweet spot or sweet tooth for them.

Lastly, I would to touch on the invasive specie the nutria. These creatures have the appearance of a rat and a beaver. The nutria was imported from South America for the fur trade in 1899 according to the U.S. Geological Survey (Emerald). Early accounts claim that the spread of nutria’s was a result of hurricanes that released them from containment and then they reproduced vastly. During the 1950’s nutrias were popular among farmers to generate additional money, but the market soon became over flooded. This resulted to nutrias either being killed for their fur or were simply released into the wild. More recently, nutria’s are now reflected as a destructive force. These invasives dig tunnels reaching 20 feet long and amount to one to two feet wide, occasionally meeting up with other tunnels, weakening the soil which can cause erosion and collapsing of important structures we depend on. Also, nutria’s destroy the places by feeding on the lower stems of river plants which disturbs the ecological balance of species. The public seems to view nutria’s more as a rat than a beaver.

"Emerald Chapter, Native Plant Society of Oregon -- Invasive Plants." Emerald Chapter, Native Plant Society of Oregon -- Invasive Plants. N.p., n.d. Web. 08 Aug. 2015.

"Invasive Species Prohibited Plant List." Eugene Parks and Open Space. City of Eugene, n.d. Web. 8 Aug. 2015.

"Noxious Weeds." Himalayan Blackberry and Evergreen Blackberry Identification and Information. N.p., n.d. Web. 08 Aug. 2015.

Simpson, Charlene. "Alien Invaders: Noxious Weeds and Invasive Ornamentals Found on Goodpasture Island." Goodpasture Island Neigbors. N.p., n.d. Web. 8 Aug. 2015.