Increased Spread of Japanese Knotweed
OBSERVATION: This observation was made by myself, James Foran, while driving from Gibsons, BC, to Sechelt, BC, on multiple instances between January and April, 2016. The Sunshine Coast Highway which is the main highway between Gibsons and Sechelt has seen increasingly persistent and invasive Japanese Knotweed growth, and while this observation is specific to the region between Gibsons, BC, and Sechelt, BC, this is merely a small sample of a much larger invasion. I have noticed more of the Japanese Knotweed species plants along this drive and in addition to actually observing an increase in the physical plant itself, I’ve also observed increased local media coverage and increased signage indicating that the areas have been affected by invasive species. Furthermore, there has been an increase in signage indicating test-plots for both organic and chemical treatment to stop the invasion. While the species is not new to the areas, the conditions of late have allowed for the species to expand incredibly quickly. The combination of local media coverage, increased signage and test-treatment areas would reinforce that my observation of a rather explosive increase of Japanese Knotweed is accurate.
General supplementary information about Japanese Knotweed.
Identifying Characteristics (Royal BC Museum, 2011): • Grows up to 3 metres high • Grows in dense thickets • The stems are woody and hollow, and bamboo-like, with pale green and purple specs on the stem • Dark green, oval-shaped leaves with a point at the top, 10-15cm long • Leaves grow on arching stems in a zig-zag pattern • Flowers with small, white or cream coloured flowers in the spring • Nicknamed ‘Mexican Bamboo’
Japanese Knotweed (Fallopia JaponicaI) is native to Eastern Asia and was introduced to North America in the late 1800’s, though an exact date is not known. It was introduced for home décor and planted for erosion control, however it has been classified as invasive and has potential to damage roadways and home foundations (The Weather Network, 2016). While digging and cutting the knotweed is a potential solution, this can actually cause the rhizomes to break up, creating more growth. There is currently no bio-treatment that has proven effective, and even chemical control is not entirely effective (The Weather Network, 2016).
I have included photos which illustrate a sample of some of the signage that has recently been added along the highway, and a photo of the plant itself. The references for these images and in-text citations are provided at the end of this post.
As per the scope of this assignment, I have sought out some potential consults, which I will contact directly as per the assignment instructions. The experts that I have invited to review and comment on this observation are:
Ian Levitt, MREM, P.Ag., R.P.Bio Project Manager – Environmental Services Stantec
I have invited Ian to act as my preferred or expert consult on this observation, and he was able to provide a wealth on information on the species in general, as well as the challenges of containment and combating the spread of Japanese Knotweed based on his personal experience in working with this species. Ian was kind enough to provide me with details on a specific project he worked on, but asked me to omit the name of the client due to confidentiality restrictions. By way of example, he was able to portray how effective this species has been at adapting to conditions in North America. As such, I have transcribed his observations while leaving out the specific client for whom this project was completed for. Transcribed from our conversation:
Japanese Knotweed has gained a significant foothold in the lower mainland, and has seen an increase in abundance and geographical spread due in part to more favorable climate conditions; a by-product of global warming. Temperatures as low as -25°C to -35°C are necessary to kill off the Japanese Knotweed naturally, and this has historically kept this species in check geographically. As the climate in the Lower Mainland (and elsewhere) warms, we are not seeing the low temperatures as frequently in certain areas, and this has allowed the species to migrate north to higher latitudes, as well as east across the mountains. (I have included an image which highlights the spread of the plant within BC).
Japanese Knotweed is known to have very extensive root (rhizome) systems and can send roots down as far as 3m below the surface, and can run roots as far as 10m laterally under the surface of the soil. Additionally, it takes only a section of root with a length of 3” to take hold and grow, making the species very resilient and difficult to contain. Strict controls must be implemented for the removal of this species, and there is still no guarantee that the methods will work.
On one project which was conducted [by Ian in his capacity with Stantec] to remove the species before commencing a construction project by a client, there were several phases required to contain, kill and remove the invasion. Even with these steps and careful planning, it was not guaranteed that the process would work; evidence of how hardy this species is. The first step was a site-survey to identify and ‘flag’ off the species with flagging tape, leaving a 12-meter buffer from the outer edge of the above-ground visible plant to accommodate for the potential of the root growth under ground. The next step was to use chemicals to weaken and try and kill as much of the plant as possible. Broad-leaf herbicide sprays have proven ineffective in the past, so stem injection was required using a glyphosate-based injection. This was allowed to take effect over a period of 1-2 weeks, allowing the toxin to travel throughout the rhizome system.
In order to have the best chance to remove the invasion, the site was excavated to below 3-meters from the surface and a minimum of 10-meters buffer from any shoots which protruded above the ground. The location where the trucks were loaded was also then excavated to account for any soil or roots that may have fallen during the excavation and loading process. The excavated earth was taken to a quarry, where is was dumped and covered with a minimum of 3m of additional earth to try and smother any surviving roots or clippings from reaching the surface, treating the removed species via anaerobic digestion as a means of degrading the waste. The site was then monitored, and continues to be monitored to gauge the effectiveness of the excavation.
This treatment, while aggressive and thorough, illustrates the ability of the plant to survive and prosper. Despite all planning, this was not guaranteed to remove the invasive species, but offered what was considered the best chance for success upon analysis of the site and alternative options available.
Stephen Roberts, B.Comm, MREM Socio-Economic Analyst Stantec
Stephen has worked on various projects related to the socio-economic aspects of invasive species including projects where Japanese Knotweed has been prevalent. Though he has not specifically worked on projects on the Sunshine Coast corridor specific to my example, he was able to provide high-level commentary related to this species, with a specific focus on the economic impacts. I’ve transcribed points from our conversation below:
Japanese Knotweed has shown the ability to push through both asphalt and concrete, and can cause significant problems for infrastructure including bridges, tunnels, retaining walls, overpasses, and parking lots. As such, this has serious implications on new construction as well as existing projects. The tenacity of the plant is cause for concern as it can weaken the structural integrity of infrastructure resources to the point of becoming unsafe. This presents a real challenge and requires continued observation and culling or removal of the species to maintain safe infrastructure.
There are three categories of costs associated with the treatment of this type of stubborn invasive species: direct, indirect and induced effects (increase in jobs to combat the spread, etc.). Additionally, there are negative implications such as the fact that the provincial government in BC does not have a specific budget designated to the control of the species, implying that any capital expenditure is money that was previously allocated to different budget items and has had to be repurposed. This has been the case in treatment to date.
From a trade perspective, this has been hugely problematic for agricultural and in some instances forest product cross-border trade. In short, many of our primary or extractive industries are feeling the effects two-fold. The first being that as an invasive species takes hold and proliferates, it chokes out native species, often crops, decreasing crop yield and directly impacting revenue. Further to this, there can be restrictions placed on crops from ‘invasive-species contaminated areas’ to restrict the potential for these crops to take root in a new geographic region. These trade restrictions can also directly impact revenue and earning potential. One other manner in which there can be economic considerations is that land with invasive species, or land neighboring invasive species can see a real decline in property value. As the spread of invasive species increases due in part to more favorable conditions, so to does the costs to keep these species in check.
Dr. Michael Kiraly, Ph.D, Instructor – Biology, Capilano University & Marine Enthusiast
Dr. Kiraly is a long-time friend of mine and was willing to speak with me about this. In addition to being a biology professor at Capilano University, he is an avid outdoor enthusiast whom I’ve spent a great deal of time in various backcountry areas of British Columbia. We have witnessed areas where invasive species have been able to take root and choke out local species. Dr. Kiraly has also helped to organize invasive species 'pull' workshops as Capilano University as he and his colleagues recognize the implications of such noxious invasion. Due to his background and enthusiasm for various aspects of marine ecology, I spoke with him regarding the implications of invasive species in proximity to rivers and waterways in terms of erosion potential. The biggest concern pertains to teh compromised integrity of retaining walls and less permanent concrete damns and buttresses often used by the mining industry. We spoke as well of waterways acting as a conduit for the species to relocate. The primary concern here is that this more rugged and opportunistic species will choke out the natural flora in said areas and disrupt the food supply to heterotrophs living in those affected areas.
References
Coastal Invasive Species Council. 2016. Do Not Mow Signs. Retrieved from Coastal ISC
Google. 2016. Map - Sechelt BC
Invasive Species Council of BC. 2014. Knotweeds. Retrieved from City of Abbotsford
Contributing Members
|
James Foran
|