The wide occurrence and expansive nature of invasive plant species are worldwide problems because these plants by their competitive character can lead to the loss of biodiversity. As a result, they significantly disrupt ecosystems, create economic damage and threats to human health, and diminish the quality of recreational resources. Therefore, sustainable, bio-based solutions are needed for their control, focusing on the utilization of their biomass after eradication. To better understand the potential application possibilities of invasive plants and their potential role in bioeconomy, species such as Lupinus polyphyllus—Lindl., Impatiens glandulifera Royle, Heracleum sosnowskyi Manden, Solidago canadensis L., Echinocystis lobata (Michx.), and Elodea canadensis Michx. were studied. These plants are not only widely spread but also form dense mono-stands and produce substantial amounts of biomass, which provides more options for their harvesting. In particular, their composition was analysed to assess the feasibility of their use for bioactive compound extraction. The amount of total polyphenols and flavonoids was determined in various parts of the studied invasive plants, and their corresponding radical scavenging activities were determined using DPPH, ABTS, FRAP and CUPRAC. The studied invasive plants are rich sources of polyphenols, and the highest concentrations were found in Impatiens glandulifera leaves, reaching a concentration of 7.78–11.75 g GAE/100 g DW, but in Lupinus polyphyllus, the highest concentrations of polyphenols were identified in the extracts of the flowers (12.77 g GAE/100 g DW) and leaves (11.88 g GAE/100 g DW) of the plant. Among the various plant parts studied, the leaves and flowers consistently showed the highest concentrations of polyphenols and flavonoids, as well as the greatest antioxidant and radical scavenging activities. These findings underscore the potential of invasive plant biomass as a source of valuable bioactive substances, particularly polyphenols, after the eradication of these invasive species.

The aim of this study was to demonstrate the utilization of invasive plant materials a resource for energy production, applying pelletization and pellet pyrolysis, thus integrating plant eradication efforts with renewable energy solutions and valorization of plant biomass. The approach was demonstrated for three invasive plants – Japanese knotweed [Reynoutria japonica (Houtt.)], Jerusalem artichoke [Helianthus tuberosus (L.)], and Canadian goldenrod [Solidago canadensis (L.)] which are abundant in Northern Europe and elsewhere. As binder materials for pellet formation, sapropel and peat extraction residues were selected for their sustainability potential, as both represent organic waste materials that, similarly to invasive plant biomass, face a high likelihood of being disposed of without added value if not valorized. The calorific value of biomass plant pellets is comparable to values common for wood pellets and other plant materials, thus supporting their use for energy production. Pyrolysis provides possibilities to obtain biochar with increased specific surface area and higher caloric content, as well as application potential in agriculture. The studied invasive plant pellets do not contain elevated concentrations of heavy metals or other pollutants, thus supporting their application for the production of bioenergy or as a soil amendment.

Invasive plants can be considered as a significant environmental threat, affecting biodiversity, agriculture, and forestry, which makes their control necessary. At the same time, invasive plant biomass is a valuable resource, and different applications can be demonstrated to support their eradication efforts. The aim of this article is to develop polyphenolic extraction methods from three Reynoutria species, characterize them, and demonstrate invasive plant polyphenol use for plant pigment stabilization using a copigmentation approach. Comparison of different extraction methods of polyphenolics provided an opportunity to increase extraction yields. The extracts were rich in anthraquinone polyphenolics, confirming the application potential of the obtained extracts and Reynoutria species biomass utilization possibilities. Reynoutria polyphenolics can be used to stabilize plant anthocyanins according to the copigmentation mechanism, and the stabilization effect depends on polyphenol concentration and temperature. Thus, invasive plant biomass waste can be used to obtain valuable substances and thus support their eradication efforts.