Passive reestablishment of riparian vegetation following removal of invasive knotweed Polygonum. Japanese knotweed and congeners are invasive to North America and Europe and spread aggressively along rivers establishing dense monotypic stands, thereby reducing native riparian plant diversity, structure, and function.
Noxious weed control programs attempt to eradicate the knotweed with repeated herbicide applications under the assumption that the system will Impacts of invasive riparian knotweed on litter decomposition, aquatic fungi, and macroinvertebrates. Bohemian knotweed Polygonum X bohemicumthe hybrid between Japanese and giant knotweedis the most common invasive knotweed species in western North America and the most difficult to control.
Invasive knotweed congeners spread aggressively along streams and establish dense monotypic stands, reducing riparian plant species diversity Providing land managers with appropriate data can Elucidating the population dynamics of japanese knotweed using integral projection models especially challenging when there is limited data on potentially important transitions that occur belowground.
For 2 years, we monitored 4 clonal Japanese knotweed Polygonum cuspidatum infestations for emergence, survival, shoot height until leaf senescence, dry shoot biomass after senescence, and rhizome connections for shoots. We developed an integral projection model using both final autumn shoot height and shoot biomass as predictors of survival between years, growth from year to year, and number of rhizomes produced by a shoot fecundity. Elasticity analysis revealed population growth at 3 of the 4 sites was primarily due to ramet survival between years and to year-to-year growth in shoot height and shoot biomass.
Population growth at the fourth site, the most disturbed, was due to the large production of new rhizomes and associated shoots. In contrast to previous studies, our excavation revealed that most of the shoots were not interconnected, suggesting rhizome production may be limited by the size or age of the plants, resource availability, disturbance frequency, or other factors.
Future integration of plant population models with more data on belowground growth structures will clarify the critical stages in Japanese knotweed life cycle and support land managers in their management decisions. Evaluation of herbicides and application timing for control of japanese knotweed: Testing was conducted from fall through spring to evaluate the efficacy of several herbicides, timing of: Lessons from Control Tests in Belgium.
Japanese knotweed Fallopia japonica is "Elucidating the population dynamics of japanese knotweed using integral projection models" extremely abundant invasive plant in Belgium and surrounding countries.
To date, no eradication method is available for land managers facing the invasion of this rhizomatous plant. We tested different chemical herbicides with two application methods spraying and stem injectionas well as mechanical treatments, on knotweed clones throughout southern Belgium.
The tested control methods were selected to be potentially usable by managers, e. Stem volume, height and density reduction were assessed after one or two years, depending on the control method. Labor estimations were made for each control method. No tested control method completely eradicated the clones. Stem injection with glyphosate-based herbicide 3.
The following year, though, stunted shoots appeared. Among the mechanical control methods, repeated cuts combined with native tree transplanting most appreciably reduced knotweed development. The most efficient methods we tested could curb knotweed invasion, but are not likely to be effective in eradicating the species. As such, they should be included in a more integrated restoration strategy, together with prevention and public awareness campaigns.
Japenese Knotweed Pest Alert. Japanese knotweed is native to Eastern Asia, and is one of the first plants to appear on volcano slopes after volcanic activity. It was introduced to the United Kingdom as an ornamental inand from there to North America in the 19th Century.
It appears to require high-light habitats, and does very well along roadways and rivers. It reproduces by seed and large Understory dominance and the new climax: Impacts of Japanese knotweed Fallopia japonica invasion on native plant diversity and recruitment in a riparian woodland. Abstract Riparian forests exhibit levels of ecological disturbance that leave them especially prone to biological invasions.
Japanese knotweed Fallopia japonica is particularly suited to these habitats and is an aggressive invader along watercourses throughout its now-global range as an exotic invader. Defining a baseline intact community composition will inform restoration plans for local Elucidating the population dynamics of japanese knotweed using integral projection models forests where knotweed might be eradicated or reduced.
Invaded and non-invaded sites differed statistically across species richness, species density, and tree recruitment. Our results suggest that F. The species also appears to have suppressed long-term tree recruitment, setting up a trajectory whereby the eventual decline of trees currently in the canopy could shift this community from a tree-dominated riparian forest to a knotweed -dominated herbaceous shrubland.
Hybridization increases invasive knotweed success. Hybridization is one of the fundamental mechanisms by which rapid evolution can occur in exotic species. If hybrids show increased vigour, this could significantly contribute to invasion success.
Here, we compared the success of the two invasive knotweedsFallopia japonica and F. Using plant material from multiple clones of each taxon collected across a latitudinal gradient in Central Europe, we found that knotweed hybrids performed significantly better in competition with a native community and that they more strongly reduced the growth of the native plants.
One of the parental species, F. We found substantial within-taxon variation in competitive success in all knotweed taxa, but variation was generally greatest in the hybrid.
Interestingly, there was also significant variation within the genetically uniform F. Our study shows that invasive knotweed hybrids are indeed more competitive than their parents and that hybridization increased the invasiveness of the exotic knotweed complex.
Effect of invader litter chemistries on soil organic matter compositions: Carbon fixation during photosynthesis forms the precursor of all organic carbon in soil and the predominant source of energy that drives soil microbial processes; hence the molecular identity of the fixed carbon could influence the formation of soil organic matter SOM.
Due to their high resource acquisition and resource use efficiencies, some invasive plants can input disproportionately high quantities of litter that are qualitatively distinctive, and this could influence the accrual of organic carbon and overall carbon cycling in invaded habitats. Hence, we hypothesized that invasive plants with unique litter chemistries would significantly influence the overall carbon cycling in the invaded soils.
We tested this hypothesis by comparing plants exhibiting recalcitrant vs. Japanese knotweed produces low litter abundant in polyphenols which selectively hinders microbially mediated decomposition and re-synthesis; whereas kudzu produces low C: N, high quality litter that can stimulate microbial decomposition. Soil samples were collected at 5-cm intervals and from inside and outside 15 to 20 year old stands of the invasive species.
The novelty of our study was that both of our study species were invading into soils of contrasting substrate qualities relative to the invading litter quality.
The molecular composition of carbon in Elucidating the population dynamics of japanese knotweed using integral projection models soils and the degradation stage of the SOM were assessed with a biomarker approach using gas chromatography-mass spectrometry to determine the source of biomolecules plant or microbes. Stability of SOM fractions was assessed through oxidation with hydrogen peroxide, serving as a proxy of biological degradation, followed by stable isotope analysis.
Fungal communities dominated the uppermost soils under knotweed whereas kudzu litter suppressed fungal biomass in the top cm. In constrast, increase in active microbial biomass C. Background Japanese knotweedReynoutria japonica, is known for its high growth rate, even on adverse substrates, and for containing organic substances that are beneficial to human health. Results In the pot experiment, plants were grown on different substrates that varied in organic matter and nutrient content, namely the content of nitrogen and phosphorus.
Nitrogen was also introduced into the substrates by melilot, a leguminous plant with nitrogen-fixing rhizobia. Melilot served as a donor of mycorrhizal fungi to knotweedwhich did not form any mycorrhiza when grown alone. As expected, the production of knotweed biomass was highest on high-nutrient substrates, namely compost.
However, the concentration of the organic constituents studied was higher in plants grown on clayish low-nutrient substrates in the presence of melilot.
The content of resveratrol including that of its derivatives, resveratrolosid, piceatannol, piceid and astringin, was significantly higher in the presence of melilot on clay, loess and clayCS. Nitrogen supplied to knotweed by melilot was correlated with the ratio of resveratrol to resveratrol glucosides, indicating that knotweed bestowed some of its glucose production upon covering part of the energy demanded for nitrogen fixation by melilot's rhizobia, and that there is an exchange of organic substances between these two plant species.
The three-year field experiment confirmed the ability of. Extreme differences in population structure and genetic diversity for three invasive congeners: Japanesegiant, and the hybrid Bohemian knotweeds Fallopia japonica, F. The distribution of these species in western North America, and their mode of invasion, is relatively unresolved Bohemian knotweed spreads aggressively along rivers.
This invasive weed chokes waterways, displaces native plants, erodes riverbanks, and keeps tree seedlings from growing. Communities in the Pacific Northwest spend millions of dollars to eradicate it on the assumption that it harms fish habitats. But knotweed is difficult to kill. Some genotypes are known to be tolerant to the saline concentrations found in salt marshes.
Here we focus on tolerance to higher concentrations in order to assess whether the species are able to colonize and establish in highly stressful environments, or whether salt is an efficient management tool. At the two highest concentrations, their leaves withered and fell. There were no effects on the aboveground parts at the lowest concentrations.
Belowground dry weight and number of buds were reduced from 30 and g L-1 of salt, respectively. In a second experiment, a single spraying of g L-1 of salt was applied to individuals of F.
Regeneration was delayed by the salt treatment and shoot growth slowed down. This study establishes the tolerance of three Fallopia taxa to strong salt stress, with no obvious differences between taxa.
Their salt tolerance could be an advantage in their ability to colonize polluted environments and to survive to spills of salt. Research Experiences from Austria. They often form dense stands along Rivers and have negative impacts on biodiversity and ecosystem functioning and also threaten the stability of river banks.