The annual plant Impatiens glandulifera (Himalayan balsam) is the most widespread invasive non‐native weed in the British Isles. Manual control is widely used, but is costly and laborious. Recently, ...biological control using the rust fungus Puccinia komarovii var. glanduliferae has been trialled. We designed an experiment to assess the impact of these control methods on invertebrate communities in relation to unmanaged and uninvaded habitats, and to determine whether mycorrhizal inoculation aided post‐control recovery of these communities. Sixty invaded and twenty uninvaded field soil blocks were transplanted to the experiment site, where a mycorrhizal inoculum was added to half of all blocks. Biological and mechanical control treatments were applied to twenty invaded blocks independently; the twenty remaining invaded blocks were left intact. Above‐ and belowground invertebrate samples were collected from the blocks at the end of the growing season. Overall, aboveground invertebrate abundance increased with the removal of I. glandulifera, and several groups showed signs of recovery within one growing season. The effect of mechanical control was more variable in belowground invertebrates. Biological control did not affect aboveground invertebrate abundance but resulted in large increases in populations of belowground Collembola. Our experiment demonstrates that mechanical removal of I. glandulifera can cause rapid increases in invertebrate abundance and that its biological control with P. komarovii var. glanduliferae also has the potential to benefit native invertebrate communities.
Summary
Impatiens glandulifera is a globally successful invader that primarily spreads along riparian habitats; however, during the last ~20 years, it has started to colonise forests, but little has ...been published on impacts of this recent spread. Several factors may have contributed to this phenomenon: (i) high propagule pressure from large and widespread riparian populations, (ii) extensive anthropogenic and natural disturbances in the forest ecosystems, (iii) increased use of forest machinery efficiently spreading the seeds together with (iv) a wide environmental tolerance of the species. The impacts of I. glandulifera on native communities in forests are manifold. Contrasting effects are reported on native plant species diversity, richness and growth of saplings of co‐occurring species, as well as negative effects on soil mycorrhizal fungi. We suggest that the eradication of I. glandulifera populations in forests is more feasible than along watercourses because the recolonisation in forests is limited and, in some cases, populations are outcompeted by woody species during succession.
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•The role of intraspecific variation across levels of biological organization is an unanswered question in invaded and non-invaded pollination networks.•Significant intraspecific ...variation was detected in the pollen loads and pollen deposition of the invasive plant Impatiens glandulifera.•Only a few individual pollinators carried large amounts of alien pollen grains, potentially function as super-spreaders driving the invading process.•Node and structural specialization were higher for individual-based and pollen-transfer networks in comparison to species-level and pollen-transport networks.•These findings shed light on the mechanisms of the (re)organization of population niches and the invasion biology dynamics scaling-up to community and ecosystem functioning.
•Pollination networks have long been studied by quantifying plant-flower visitor species interactions. Despite making considerable contributions, this ignores important steps of pollen movement from anthers to receptive stigmas and neglects the intraspecific variation of the interacting partners. Addressing specialization and niche partitioning regarding heterospecific pollen transport and transfer, is fundamental to untangle the mechanisms behind contrasts seen in the impact of alien species on native communities.•We used two well-sampled datasets on pollen-transport and pollen-transfer networks to test how intraspecific variation in interaction specialisation affects invaded pollination networks. We considered different levels of biological organization: from species- to individual-based networks.•We found significant intraspecific variation in the pollen loads and pollen deposition of the invasive plant Impatiens glandulifera; thus only a few individual pollinators and plant stigmas carried large amounts of alien pollen grains, potentially functioning as super-spreaders driving the invading process. Consequently, most individuals carried only a few, or no alien pollen at all, possibly buffering the negative effects of invasive plants at the population and community levels.•Node and structural specialization were higher for individual-based and pollen-transfer networks, suggesting a lack of dominant, highly generalist links when downscaling from pollen-transport to pollen-transfer, and from species to individual-based networks.•The high specialization, selectiveness and niche partitioning of plants, pollinators and their interaction revealed at the different stages of the pollination process and across distinct levels of biological organization, suggest important mechanisms associated with the (re) organization of population niches. Moreover, these mechanisms provide a promising approach towards a more comprehensive understanding of the dynamics of invasion biology from population to community and ecosystem functioning.
Wood dyes from invasive alien plants Monika Horvat; Jernej Iskra; Matjaž Pavlič ...
Les (Ljubljana, Online),
12/2020, Volume:
69, Issue:
2
Journal Article
Peer reviewed
Open access
The aim of the study was to produce different types of coatings based on natural dyes obtained from invasive alien plant species and residues after paper production. As a source of dye we used ...extracts of Rhus typhina, Japanese knotweed, Himalayan balsam and Canadian and giant goldenrod. The substrates for the application of the coating were the wood of the tree of heaven and the wood of the horse chestnut. The coatings were observed visually, and the hydrophobicity of the coated surfaces was determined by measuring the contact angles of water droplets. In addition to the transparent and brown coloured coatings, we also achieved intense red, yellow, green, and brown and purple colourings. With a combination of different components, the hydrophobic properties of the coated surfaces varied. By combining an extract of giant goldenrod flowers and 3-(triethoxysilyl)propyl isocyanate, we succeeded in producing a coating with pronounced hydrophobicity. A process for the production of coloured and transparent hydrophobic coatings was developed in this research. Through the presence of various silane-containing molecules and the application of the coating to wooden surfaces, we changed their appearance and improved their hydrophobicity.
Forests understories in Europe are known to generally resist invasion, though some alien plants do invade woodland communities. Here we focused on the impact of the widespread invasive annual
...Impatiens glandulifera
, common along watercourses, but recently spreading in forests up to timberline. We investigated its impact on plant–soil feedback and ecosystem functioning. We recorded >40 variables focusing on: soil characteristics, including micro- and macro-nutrients; characteristics of litter layer and enzyme activity in litter; and richness and species composition of the forest understory. Three treatments were followed for 3 years: plots invaded by
I. glandulifera
; adjacent invader removal plots within the invaded area; and spatially separated uninvaded plots outside the invaded area. The effect of year-to-year variation was generally greater than that of the treatments, especially in soil and litter characteristics. Copper and boron were higher in invaded than invader removal and uninvaded plots, though in quantities that are unlikely to harm other plants. We found no effect of
I. glandulifera
on litter characteristics or enzyme activity. Despite almost 80% cover of
I. glandulifera
, we did not detect any difference in species richness and total vegetation cover between invaded and uninvaded plots. The floristic composition differed among the uninvaded, invader removal and invaded plots across 3 years. Our results indicate that the effect of
I. glandulifera
on the forest community studied was minor, and largely resulted from its increased shading to other plant species. In conclusion, we show how misleading the evaluation of impacts can be if based on a single season.
Purpose
A monitoring investigation undertaken along the River Ibach, northwest Switzerland over the winter 2012/2013, found that riparian areas recently supporting the invasive plant Himalayan Balsam ...(HB) recorded significantly higher erosion rates than nearby uninvaded areas. This communication sythesises the latest findings about the influence of HB on sedimentation processes, again, from the Ibach, but also from a second river system in southwest UK.
Materials and methods
Erosion pins, a micro-profile bridge and a digital caliper were used to measure changes in soil surface profile (SSP) at selected riparian areas supporting HB plants along both rivers. Values were statistically compared against equivalent data recorded from nearby reference areas supporting mixed perennial vegetation. A comparison of source and sediment geochemistry was also undertaken on soil from HB-invaded and uninvaded floodplain areas along the Ibach, to assess the potential for identifying the extent to which either group acts as a sediment source.
Results and discussion
Erosion pin data indicate that soil loss from HB-colonised areas was significantly greater than soil loss from reference areas in two out of the four periods at the River Ibach site, and in two out of three measurement periods at the River Taw site. Colonisation of new HB sites may initially occur by hydrochorous processes, but HB plants may increase colonisation potential by trapping additional fine sediment and organic matter, including viable HB seeds. Geochemical results from the Ibach suggest that high inputs of suspended sediment originate from sources close to the river channel, but HB-invaded floodplain sources have geochemical properties that are most similar to suspended river sediment.
Conclusions
The findings from both rivers led us to rethink our original hypothesis; that HB promotes soil erosion, to an amended hypothesis in which HB may be associated with areas where high erosion is sometimes recorded. Whilst initial colonisation may be due to hydrochorous processes, as HB becomes increasingly established, the displacement of perennial vegetation increases the risk of erosion during the winter period when live HB plants are absent. Preliminary geochemical findings of floodplain soils supporting different vegetation types along the Ibach tentatively suggest that at least some material originating from HB sites may enter the watercourse.
The practicality of Himalayan balsam as an alternative biomass material was considered throughout this investigation. However, due to the materials high-water content, thermal efficiency during ...pyrolysis was compromised as extra energy was required to remove free and bound water. A simple solution which involved drying at ambient temperature in air, significantly lowered the moisture content, (65% reduction) this resulted in an increase in the bulk density of the material and lowering the thermal energy input of the process. The thermal decomposition process at 300–400 °C generated petroleum like compound; a mixture of volatile aromatic, linear and branched alkanes, and therefore a possible source for replenishment of hydrocarbon-based fuel. The solid remaining carbon generated (~35% mass of dry material) termed biochar showed adsorption properties to rhodamine B dye. The level of activity was increased upon activation using phosphoric acid. The activated biochar could be a promising adsorbent used to remove aqueous organic compounds. The thermal treatment of Himalayan balsam has potential in generating useful products such as bio-fuels and biochar.
•Himalayan balsam potentially can be used as a source of biomass for pyrolysis.•The high-water content was reduced through air drying.•Air drying consequently increasing the thermal efficiency of the process.•The tar compounds revealed similarities between petroleum distillates.•The activated biochar showed affinity towards Rhodamine B.
Flower infestation by pathogens may influence pollination effectiveness. At the same time, by sharing infested flowers, pollinators increase transmission of pathogens. In the presented study we ...identified fungi that colonised flowers of the invasive alien Himalayan balsam
Impatiens glandulifera
, one of the most nectar rewarding plants in Europe, as well as its pollinators. We determined factors (e.g., plant size, length of flower lower sepal and the width of its entry, air temperature and sun illuminance) that affect pathogen species presence and pollinators numbers. The study was conducted in three regions in Poland differing in time from the
I. glandulifera
invasion onset. It allowed embedding our results in the context of the evolution of increased competitive ability (EICA) hypothesis. With reference to this hypothesis we tested whether
I. glandulifera
from the two younger populations are more frequently pollinated than individuals from the old one, which may be a result of the higher infection prevalence in the flowers of individuals from the latter population. Harmful primary pathogens of
I. glandulifera
(e.g.,
Botrytis cinerea
and
Fusarium graminearum
) were identified from its flowers. Although the knowledge of the impact of the recorded pathogen species on the pollinators that transmit them is still limited, these pathogens are known to cause devastating diseases of native plant species and to incur significant economic losses in crops. Therefore, the facilitation of their transmission by
I. glandulifera
in the invaded communities may pose a serious threat both to native biodiversity and nearby crop production. We did not find support for the EICA hypothesis that flower release from pathogens may increase the pollinator’s activity.
Bombus hortorum
was the most frequent visitor in the youngest surveyed population, while
B. pascuorum
was most frequent in the two others. So far the dominance of
B. hortorum
as a pollinator of
I. glandulifera
has not been recorded. A possible explanation is that flowers in the youngest population, with significantly wider entries than in the two older ones, were more accessible for this large bumblebee. We suggest that the shifts in flower dimensions may result from the evolutionary processes and/or phenotypic plasticity; however, this suggestion needs to be confirmed in further studies. At the same time, it can be expected that exceptionally frequent visits of
B. hortorum
in flowers of
I. glandulifera
in the youngest population may contribute to increasing transmission rate of pathogen species to the new native host plants that are particularly associated with this pollinator.
PURPOSE: The invasive plant, Impatiens glandulifera (common English name: Himalayan Balsam), is now found in many river catchments in most European countries. Its preference for damp, nutrient-rich ...soils, along with its intolerance to cold weather and rapid dieback, has implicated it in promoting soil erosion along the riparian zone. Despite the implication, its influence on the sediment dynamics of river systems remains unconfirmed. This communication reports the preliminary findings of ongoing work to investigate a possible link between I. glandulifera and accelerated erosion rates in inland river systems. MATERIALS AND METHODS: Erosion pins, a micro-profile bridge, and a digital caliper were employed to measure changes in the soil surface profile (SSP) at six separate locations, each contaminated with I. glandulifera, along the riparian zone of a small watercourse in northwest Switzerland. Changes in SSP were also measured at an identical number of nearby locations supporting natural vegetation, in order to establish baseline erosion conditions. Soil surface profiles at all 12 locations were re-measured on seven separate occasions, from October 2012 to May 2013. This covers the time before dieback occurred to the germination and seasonal regrowth of new plants. RESULTS AND DISCUSSION: A total of 720 individual SSP measurements were recorded during the above monitoring period. Increasingly negative values relative to initial values were documented at most transects, indicating a net reduction in soil surface elevations. This is interpreted as evidence of the removal (i.e., erosion) of surface material. Paired samples statistical analysis of the data indicate that erosion from contaminated sites was significantly greater than erosion from topographically comparable reference sites (t =−5.758; P < 0.05; N = 359) supporting natural vegetation. CONCLUSIONS: The results provide tentative yet compelling evidence that I. glandulifera promotes soil erosion along the riparian zone of the watercourse investigated. Given the unrelenting spread of this notoriously invasive plant throughout inland river systems in many countries, the likelihood of greater quantities of nutrient-rich sediment entering into aquatic environments may steadily reduce water quality in all affected catchments. An absence of effective control measures capable of halting or even slowing its rate of invasion may make it increasingly difficult for affected European Union member states to meet and then maintain key water quality standards set by the Water Framework Directive (WFD) when fully implemented in 2015.
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