Commercial utilization of knotweed is explored to facilitate large-scale invasive species management.
GDEV 3030 Circular Economy, Fall 2024
Climate change and pollution are widely recognized as major drivers of biodiversity loss globally. According to the United Nations’ Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), invasive species threaten biodiversity to the same relative magnitude as the looming threats identified above. In addition to biodiversity loss, invasive species are responsible for jeopardizing water and food security, public health, and livelihoods amounting to a cost of 4.23 billion USD annually. Of all the taxa of life on earth, “invasive alien plants are the taxonomic group most frequently reported as having a negative impact, particularly in cultivated areas and temperate and boreal forest” (Roy et al., 2024). Invasive plant species management is an essential aspect towards sustainability and climate justice across the globe, including in the U.S.
Historically, invasive plant species management operations in the United States have been concerned principally with eradication; management serves to improve biodiversity but does not critically seek to maximize the material and the energy/labor required to harvest it by keeping that material in circulation. Ironically, the majority of invasive plants were intentionally introduced to the United States for their “food, fiber, and/or ornamental purposes” (Pimentel et al., 2005). Invasiveness happens as a result of “increased competitive ability,” the ability for a plant to allocate resources to growth and reproduction rather than adaptations that defend against predation, provide immunity to pathogens, resist environmental stressors, etc., giving rise to an overabundance of individuals in the environment. Given their inherent utility and abundance, invasive species are an incredibly underutilized resource (especially in the context of widespread land conversion for crop cultivation). I propose that invasive species management is approached from a circularity perspective, where biodiversity improvement (“regenerating nature”) is accomplished alongside/in association with the utilization of their organic wastes and extension of the lifespan of these materials through commercialization.
Commercialization has a number of associated advantages and challenges. The idea behind commercializing invasive plants is to add economic incentives to their management that currently do not exist in order to spread awareness of species, accelerate their control, and offset costs of management (Borokini & Babalola, 2012). However, because they are not cultivated resources, gaps in knowledge, inefficiencies, and economic losses are inherent. Experts in invasive plant commercialization advocate for a stakeholder-led process, economic benefit as a secondary goal, management plans prioritizing key sites, consideration of transportation and limiting species spread, restoration following removal, and engagement in biomass energy systems (Dasgupta, 2023). Using these guidelines to design management schemes through commercialization is critical.
As a case study in commercialization in central New York, I selected knotweed (Fallopia japonica syn. Reynoutria japonica, Polygonum cuspidatum) due to its global abundance, diverse uses, and aggressive adaptations that create challenges for management. Knotweed is a particularly problematic species outside of its native range across the globe. In the northeastern United States (specifically Massachusetts), knotweed plots were found to have 1.6-10 times less species diversity than adjacent plots without knotweed – of these species, the proportion of those indigenous to the site fell 20% in knotweed stands compared to outside (Aguilera et al., 2010). However, due to its high competitive ability, knotweed stands are incredibly dense sources of material, with up to several times greater biomass than outside of stands (ibid.). Eradication solely by cutting is possible in small stands, which must be cut back 6 times per season for multiple years before eradication (Japanese Knotweed Leaflet, n.d.). Control by harvesting has the advantages of reducing herbicide pollution, costs, and training requirements (Borokini & Babalola, 2012). It also has evidence to reduce the allelopathy of knotweed, leaving soils fit for restoration after eradication (Murrell et al., 2011). Eradication by harvest also creates an abundance of plant material that can be used and sold.
Knotweed can be used in a variety of ways with a range of infrastructural requirements. The simplest and most accessible scale in its current state is the use of knotweed as food. Young shoots (<1’) are peeled and can be used in applications similar to rhubarb; care should be taken to avoid spreading the plant when disposing of scraps (Bergo, 2015). Additionally, knotweed shows promise of possessing a number of biophysical properties, including antibacterial, antioxidant, anti-inflammatory and anticancer effects. Researchers suggest these properties could valorize the plant as food or medicine (Cucu et al., 2021). More infrastructurally demanding processes are concerned with the use of knotweed fiber as a material and knotweed biomass as a bioenergy feedstock. Companies are successfully producing paper and recyclable, biodegradable composite interior building materials from knotweed (Notweed Paper – Locally Sourced Paper from Invasive Plants, n.d., Sheet Material Made of Japanese Knotweed, 2022). Researchers also suggest using fibers in conjunction with PLA injection molding to replace wood fiber-reinforced polymers (Wunsch et al., 2022). Finally, knotweed can be used as a feedstock in bioenergy generation including combustion, anaerobic digestion, pyrolysis, and fermentation. The advantage of bioenergy is that a multitude of feedstocks can be used; knotweed and other invasives can compose a portion of the whole alongside other organic wastes and cultivated feedstocks. The abundance and homogeneity of knotweed stands is suited for mitigating issues like the contamination of feedstock with other biomass. The lack of biorefinery infrastructure in the northeast and the unknown processing requirements of invasive species represent significant barriers (Quinn et al., 2014). However, I argue that these are opportunities to establish a new industry that can be fed with biomass from the surrounding landscape until feedstock cultivation is established. Biomass can also be co-fired with coal in existing combustion plants, avoiding the need for new infrastructure altogether (ibid.). A singular or combination of these diverse uses may be the most appropriate for central New York.
The products and processes from commercialization of knotweed will impact many members of the community. Conservation and landscape management professionals will face new demand and compensation for invasive species removal. Some use models may call for individual landowner harvesting, which would give rise to landowner cooperatives (Quinn et al., 2014). Contracting jobs for invasives harvesting and management may increase as invasives management becomes more accessible with costs offsets from commercialization. It’s important that stakeholders and communities are considered in commercialization; I consider stakeholder benefit as a priority alongside eradication, followed by economic development.
An additional challenge in knotweed management schemes is preventing further spread. Commercialization and value-added processing are advantageous in terms of denaturing plant material to prevent propagation, but the process of transportation between harvesting and processing is crucial. Unprocessed uses, including culinary use and as an informal building material, are advantageous since they can occur on-site; however, because there is no centralized collection system, spread prevention is entirely up to the harvester. More processing-intensive uses like papermaking, standard construction materials, medicine, and bioenergy production have the potential to be regulated, but require harvesting at a much greater scale which increases the likelihood for small pieces to be missed. At all scales, it is crucial to understand who is harvesting and how harvesting is being conducted so that no plant material reenters the environment until it has been processed.
Ultimately, my task is to further analyze each of these opportunities against the regulatory, spatial, cultural, and economic situation of central New York. A successful project would propose the most appropriate uses of knotweed in this region, informed by existing practices and infrastructure, possibilities to establish new techniques and industries, and the possibility of coupling invasive plant wastes with other processes and materials to propose a pragmatic approach to large-scale invasive plant management through commercialization.