Invasive species

Lutz Eckstein is the lead author of a paper summarizing the current knowledge on the biology of the invasive legume Lupinus polyphyllus Lindley. The paper has recently been published in the journal Perspectives in Plant Ecology, Evolution and Systematics in the series “Biological Flora of Central Europe” (https://doi.org/10.1016/j.ppees.2022.125715). This work is a cooperation with Erik Welk (Martin-Luther-University Halle-Wittenberg and German Centre for Integrative Biodiversity Research (iDiv) Halle, Germany), Yves Klinger and Wiebke Hansen (both Justus Liebig University Giessen, Germany), Tommy Lennartsson and Jörgen Wissman (both Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden), Kristin Ludewig (University of Hamburg, Germany), and Satu Ramula (University of Turku, Finland).

The paper gives a thorough review of the species’ taxonomy, presents distribution maps for North America, Europa and the world (Fig. 1), illustrates the life cycle of L. polyphyllus, and it contains a comprehensive discussion of potential management options. During the research for this review, the authors encountered some doubtful information about L. polyphyllus that uncritically reiterates in several fact sheets, reports and webpages. One such erroneous piece of information refers to the apparently very high longevity of seeds, which was taken from a modelling study on seed longevity under optimal dry and cold storage conditions. Similarly, there is some uncertainty and large variation concerning the actual lifespan of the species. Another piece of doubtful information is the deep rooting depth of L. polyphyllus, which may rather characterize a maximum than a representative average value. Finally, the species is sometimes considered a “rhizomatous perennial” although it lacks true rhizomes. These points highlight some critical knowledge gaps, which partly relate to aspects of the species’ life cycle and morphology that may be either time-consuming or labor-intensive to study.

The authors conclude that there is currently no evidence-based strategy for a cost-efficient management of L. polyphyllus. The development of such control measures is necessary because L. polyphyllus is among the most problematic non-native plant species in Europe with respect to environmental and socio-economic impacts. The species has significant negative effects on community structure, composition, species richness and diversity, especially in nutrient-poor habitats such as alpic mountain hay meadows, alpic mat-grass swards but also nutrient-poor road verges or riparian terraces.

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Hej, my name is Hanna Paikert and I completed a three-month-long internship at NRRV. My main motivation for this internship was to gain insight into a different research environment and to expand my knowledge regarding different scientific methods. Additionally, I aimed to figure out if I want to pursue a Ph.D. (A question I can answer now: it’s a big yes!)

During my time in Karlstad, I was involved in different projects but mainly worked with Elin Blomqvist and Lutz Eckstein on the project “Evidence-based control and monitoring of Garden Lupine for the conservation of species-rich road verges”. (But see: “Fish, poop and plants: crap research isn’t as bad as it might sound.”) The Garden Lupine (Lupinus polyphyllus) is an invasive plant species originally from North America which has spread massively along road verges in Sweden. Due to its large height, its ability to fix nitrogen and the high numbers of seeds each plant can produce, it has become a threat to native biodiversity. Thus, the control of this species is of high relevance along species-rich road verges. At the beginning of my stay, I focused on the effects of heat treatment on seeds and roots of the Garden Lupine to investigate whether high temperatures could decrease the germination rate of seeds and the survival of treated root parts. This is particularly important when large soil masses, which contain seeds or roots from the Lupine are transferred from one site to another. Here we used Triphenyl tetrazolium chloride to visualize the viability of the roots and seeds after the treatment. The red color indicates viability, no staining shows a dead plant part (see figure 1).

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With the beginning of summer, field season started. I joined Elin while setting up the plots for a mowing experiment which comprises eight sites all over Värmland and will go on for the next three years. The goal is to investigate the effects of different mowing heights and frequencies on the spread of the Garden Lupine, as well as the native species richness. After the experiment was set up, we started with species inventories in which I got to expand my knowledge of species identification and gained a lot of botanical vocabulary in Swedish [😊]. During my last weeks, I assisted Elin with the first round of mowing and was lucky enough to see some drone flights to visualize the spread of Lupine from the air. Due to the fact, that the sites for this experiment are located all over Värmland, I was very lucky to see a lot of beautiful places as well as some wildlife (see figure 2)!

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Last but not least I want to thank my supervisor Lutz Eckstein who coordinated my stay and gave me a lot of tips for my future career, Elin Blomqvist for great times in the field and her patience in teaching me “botanical Swedish”, Jaqueline Hoppenreijs and Sebastian Rock for taking me along to the field. A big thank you goes out to the whole department who welcomed me very warmly and made me feel included from day one! It was great getting to know you and getting a sneak peek into your research!

Lutz Eckstein, professor at Karlstad University, is involved in a recently published paper, studying techniques for control of the invasive Garden Lupine (Lupinus polyphyllus) and the introduction of target species in mountain meadow plant communities.

This paper with Wiebke Hansen as the lead author, published in the journal Restoration Ecology (https://doi.org/10.1111/rec.13682), tested the restoration techniques “seed bank activation” and “green hay transfer” in combination with “manual removal of the invasive L. polyphyllus” on three types of grassland (Nardus grassland, mesic and wet mountain hay meadows) in the Rhön UNESCO Biosphere Reserve in Central Germany.

The main implications for restoration practice are the following:

• Green hay application might not be a suitable tool for restoring Nardus grassland since small species might not be able to grow through the plant material layer.
• Lupinus polyphyllus cover on restoration sites can be reduced by manual removal of all parts of the plants, but a lasting reduction requires at least repeated applications
• Reinvasion of Lupinus polyphyllus into restoration sites must be prevented with an appropriate management, e.g. early and/or repeated mowing.
• Active restoration through seed bank activation failed to promote mountain meadow target species and reduced the cover of wet mountain hay meadow target species.

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Road verges act as important refuges for grassland species since the areas of semi-natural grassland have declined during the last century. However, as linear habitats, road verges increase connectivity in fragmented landscapes, which also makes them prone to colonization by non-native species. This is currently seen as the greatest threat to species-rich road verges. The invasive Garden Lupine is commonly found in road verges where it alters competitive interactions, reduces native populations, and even causes extinctions of native species. 

This project is funded by The Swedish Transport Administration (Trafikverket) and the aim is to improve ecosystem functions and services of species-rich road verges and green infrastructure through evidence-based control and monitoring of Garden Lupine at the landscape scale.

During this seminar, I’m going to introduce the background for the project, and talk about what has been done and what I am planning to do in the next years.

The seminar will be streamed live over zoom on Tuesday 26th April at 13.15 CET. The zoom link for the seminar is https://kau-se.zoom.us/my/kaubiology. You are welcome

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Dr. Hein van Kleef from the Bargerveen Foundation in The Netherlands will give a seminar entitled Sailing mostly uncharted waters when applying concepts of ecosystem resilience to enhance invasive resistance. This seminar will be streamed live over zoom on Tuesday 29th March at 13.15 CET through https://kau-se.zoom.us/my/kaubiology

Professor Lutz Eckstein is involved in a new report led by Tommy Lennartsson (SLU) and co-authored by Jörgen Wissman and Jan Olof Helldin (SLU), published by TRIEKOL, a group of scientists dedicated to applied rail and road ecology.

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The report summarizes the role of invasive alien plants (IAP) in the context of infrastructure habitats, focusing on the importance of research for the development of measures for the management and monitoring of invasive species. It elaborates on three problem complexes with IAP:

(A) Effects of IAP on biological diversity and the possibility to reach the Swedish environmental objectives;

(B) The role of the organization and activities of the Swedish Transport Administration and of community valuations, laws and rules for the work with IAP; and

(C) The development and evaluation of measures for control of IAP. For each problem complex, a number of specific questions are formulated highlighting critical knowledge gaps that need to be addressed by scientists.

Download the report here: https://triekol.se/project/kunskapsbrister-invasiver/.

RivEM is looking for a PhD candidate to work on evidence-based control and monitoring of Garden Lupine for the conservation of species-rich road verges. The project is part of a larger commitment of the Swedish EPA, the Swedish Transport Administration and Formas on management and control of invasive organisms. The work will take place in southern Sweden and you will be supervised by Lutz Eckstein, Lovisa Lind Eirell (Biology) as well as Jan Haas and Jan-Olov Andersson (Geomatics).

The main tasks of the successful candidate involve to plan, conduct and analyze field experiments directed at controlling the cover and spread of the invasive Garden Lupine. This will include (i) identifying the optimal timing of management, (ii) evaluating the use of different mowing techniques (timing and the regime) as a controlling agent for the Garden Lupine, and (iii) exploring unconventional control measures on the Garden Lupine and their effects on the native vegetation. Additionally, using data derived from geographic information systems (GIS) and un-crewed aerial vehicles (UAV), the candidate will (iv) develop a method for cost efficient monitoring of lupine populations and for evaluating the success of control measures at the landscape scale. Read more about the position and apply at https://kau.varbi.com/en/what:job/jobID:379605/

Tired of slugs eating fruit and veggies in your garden? Big holes in your strawberries? Johan Watz and Daniel Nyqvist (Politecnico di Torino, Italy) have a new paper out on the performance of copper and waterglass (sodium silicate) barriers against movements of Spanish slugs (Arion vulgaris).

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Copper foil barriers delayed, but did not prevent slug passage. Waterglass, on the other hand, prevented passage completely and reduced crop damage in a semi-field validation. You can read the full paper here: https://www.sciencedirect.com/science/article/pii/S0261219420304580