Evaluation of Restoration Efforts in the Tryon Creek Watershed

Restoration work taking place this Summer

A group of Portland State University students have spent the last two months visiting previous restoration sites in the Tryon Creek Watershed. The students visited each site and took account of the amount of native versus invasive species of current plants, and the general success rates of past re-plantings. The focus was to help the Tryon Creek Watershed Council be aware of which sites are still in need of eradication of invasive plant species that are preventing native species from thriving.

What’s the big deal about invasives?

Invasive species are a threat to biodiversity and water quality.

  • Non-natives can spread from the confines of a private yard or garden on shoes, in the wind, or by animals.
  • When they enter a foreign ecosystem, they compete with the existing native species for resources. Invasive species are often more adaptable than native species, and grow rampantly without animal predators in the area that are unable to digest the introduced plant.
  • The result is that the invasives eventually become one of the main species in the ecosystem, decreasing biodiversity
  • As a result, this promotes soil erosion because lack of plants suited to hold back water banks and slow water absorption leads to more sediment in the waters. The warmer, cloudier water makes it very difficult fish to spawn or for bacteria to maintain a balanced water quality
  • Without a broad range of different species of plants, animals, insects, etc. living in an ecosystem, the entire ecosystem can collapse.

Not all non-natives are created equal

The non-native plants that compete for resources such as sunlight and water are the ones that pose a threat to beneficial native species. The following are some common invasive species the Portland State University students documented. Some have easily mistakable native “look alikes,” which are also listed, along with the main ways to differentiate between the native and invasive types:

Invasive

Holly
This is an invasive species that is identified by its glossy leaves which protrude along the stem alternatively. This plant produces bright red berries.
 

tryon-creek-invasive-species-holly.jpg

Native

Oregon Grape
Unlike its invasive counterpart, its leaves are less glossy and the leaves on either side of the stem are parallel to one another, almost in pairs. The berries it produces are a dark blueish purple.

tryon-creek-native-species-oregon-grape.jpg
 

Himalayan Blackberry
This species of berry has thick, branch-like stems with strong thorns. The leaves come off the stem in groups of five.

 
 
tryon-creek-invasive-species-himalayan-blackberry.jpg

Oregon Blackberry
This native species of blackberry has more vine-like stems, and the leaves are in groups of three. Additionally, the plant looks less malicious as there are less thorns and the stem is more flexible compared to its invasive counterpart. There is also a white coating along the stem in this species.

tryon-creek-native-species-oregon-blackberry.jpg
 

Other invasives are much more obvious to identify as they possess characteristics unlike other plant-life in the area such as:

Hawthorn

An invasive plant that grows into a tree. It eventually has had white buds that bloom into small flowers.

tryon-creek-invasive-species-hawthorn.jpg

English Ivy

A green vine that can be found blanketing ground cover, engulfing shrubs and can also take over trees of any size. It can be identified by its dark, green waxy leaves with three to five points from a heart-shaped base.

tryon-creek-invasive-species-english-ivy.jpg

Stinky Bob / Herb Robert

This invasive plant is easily identified by its pungent smell, along with its red stem, parsley-like leaves, and purple flowers–when in bloom.

tryon-creek-invasive-species-stinky-bob.jpg

Creeping Buttercup

As the name might suggest, this invasive species is a type of ground cover and produces yellow flowers with three to five petals. Growing on hairy stocks, the green jagged leaves are grouped into three with a central leaf

tryon-creek-invasive-species-creeping-buttercup.jpg

Morning Glory

Sometimes called Bind Weed, this plant can grow quickly and can be difficult to get rid of. It climbs up other plants to gain access to more sunlight and because it is not native, it can out compete plants it has latched onto. It has a spade shaped leaf which grows off of a vine once the vine has wrapped itself around the stem of another plant.

tryon-creek-invasive-species-morning-glory.jpg

Horsetail

Though highly prevalent and somewhat exotic-looking, the soft-spoked stalks of distinctive horsetail is a native forb to Oregon. They flourish in the hot summer months, then fade in the Autumn.

tryon-creek-invasive-species-horsetail.jpg
 

What can you do to help?

Volunteer with the Friends of Tryon Creek Eco Crew the first and second Saturday of each month.