Garden Lupine (Lupinus polyphyllus) native to North America has been classified as an invasive species in Sweden. In Sweden, they are mainly distributed in road verges. A group of researchers at Karlstad University led by Prof. Lutz Eckstein has been tasked with finding efficient management strategies to control their spread. The research aims at finding out when the garden lupine can be controlled most effectively. Watch Prof. Lutz Eckstein and doctoral student Elin Blomqvist talk about this research in a video interview as they collect and examine lupines at different stages of development.

Watch the full video here : https://tinyurl.com/mbnjhmh

Professor Lutz Eckstein is senior author in a new paper in the journal Applied Vegetation Science led by Zahed Shakeri (Kassel University, Germany). Livestock grazing is still an important disturbance in many forest ecosystems of the world. While studies have addressed the general impact of different grazing and light intensities on temperate forest ecosystems, little is known about how the combination of these two factors can affect the species pool and functional diversity of temperate forests.

The authors studied vegetation and environmental data of 104 relevés from Oriental beech forests (Fagus orientalis) of northern Iran. These were assigned to four groups based on their light and grazing intensities. Non-metric multidimensional scaling was used to analyze vegetation compositional relationships among groups. They used nine functional traits related to growth, reproduction, and survival for a total of 147 plant species. Redundancy analysis of community-weighted means was used to determine the response of single traits to disturbance and environmental variables. Both light and grazing intensities significantly affected species pools, single traits, and functional divergence. Suites of trait attributes including hemicryptophytes, therophytes, grass-like, hygromorphic leaves, insect-pollinated, rhizomes, and runner plants were associated with high-light sites. In closed-canopy (low-light) sites, the strong filtering effect of shade resulted in suites of trait attributes including taller plants, macrophanerophytes, scleromorphic leaves, simple leaves, and berry fruits. While high-light sites had a larger species pool, they exhibited less functional diversity. Cattle grazing can mediate the filtering effect of light, and increase functional diversity in both low-light and high-light sites. Conservation measures in this region should acknowledge that moderate traditional cattle grazing combined with individual-tree and group-tree selection in these forests may maintain or even enhance functional diversity in these valuable ecosystems.

Read more about the paper here: https://doi.org/10.1111/avsc.12592.

Professor Lutz Eckstein is co-author in a new paper in the journal Applied Vegetation Science led by Yves Klinger (Justus-Liebig-University Giessen, Germany). The authors assessed the role of mowing machinery and endozoochory by migratory sheep as dispersal vectors in semi-natural grasslands by comparing the species compositions and traits of species found in the vectors to the regional above-ground vegetation and soil seed bank. Plant material from mowers (n = 12 from one date) and dung samples from migratory sheep (n = 39 from 13 dates) were collected and the dispersed plant species were determined using the emergence method. We compared the species compositions to the regional above-ground vegetation and seed bank using non-metric multidimensional scaling (NMDS) and indicator species analysis. Furthermore, we compared functional traits of the dispersed species to traits of non-dispersed species of the regional species pools by calculating log-response ratios and performing metaregressions.

Sheep in the Rhön Mountains. Photo by Yves Klinger.

We found that mower samples were more similar to the above-ground vegetation whereas dung samples were more similar to the seed bank. Mowers and sheep endozoochory favored the dispersal of species with different traits and phenologies. Species with small seed sizes were prevalent in both vectors. Mowers were less selective concerning most traits, but favored high-growing grasses such as Alopecurus pratensis and Trisetum flavescens. Sheep dung samples contained less grasses and more palatable species, such as Urtica dioica.

Log-response ratios dispersal vectors vs species pools of sheep vs above-ground. LDMC = Leaf Dry Mass Content, EIV N = Ellenberg Indicator Value for Nutrients. Zero indicates the mean value of the non-dispersed species from the respective species pool, bars show mean log-response ratios ± confidence intervals. Figure is part of Figure 3 in the paper.

Sheep endozoochory and mowing machinery are complementary dispersal vectors favoring species with differing functional traits. Sheep endozoochory enables dispersal of species that have unfavorable traits (e.g. low releasing heights) or phenologies for dispersal by mowing machinery. To ensure the dispersal of a high number of plant species in semi-natural grasslands, the interplay of different vectors should be considered.

Read more about the paper here: https://doi.org/10.1111/avsc.12579.

Lutz Eckstein, professor at Karlstad University, is involved in two recently published papers, studying the effects of invasive Garden Lupine (Lupinus polyphyllus) on vegetation and seed bank of mountain meadow plant communities.

The first paper together with Wiebke Hansen (first author), Julia Wollny, Annette Otte and Kristin Ludewig, published in the journal Biological Invasions (https://doi.org/10.1007/s10530-020-02371-w), found that the invasion of Garden Lupine homogenizes vegetation composition. The similarity among plots increased with increasing lupine cover in three different vegetation types. L. polyphyllus affected species diversity in terms of richness and effective species number but in rather complex ways, i.e. plots with low to intermediate lupine cover had higher species diversity than control plots. Probably, the invasion though Garden Lupine is linked to significant species turnover. A very clear effect was found for community-weighted means of species trait. In all three vegetation types studied, the canopy height of the community increased with increasing lupine cover, whereas especially in the low-productive Nardus grasslands, leaf dry matter content decreased and specific leaf area increased. Thus, the Garden Lupine shifted the suite of community traits towards more competitive trait values. This may lead to overall more productive plant communities from which rare, low-growing herbs and grasses will disappear.

Germination experiment from the seed bank study in the paper published in Restoration Ecology. Photo: Kristin Ludewig

The second paper with Kristin Ludewig (first author), Wiebke Hansen, Yves Klinger, and Annette Otte, published in the journal Restoration Ecology (https://doi.org/10.1111/rec.13311), analyzed the effects of increasing cover of Garden Lupineon the seed bank of mountain meadows, and the potential of the seed bank of these stands for active restoration of mountain meadows in terms of species composition and number. The authors conducted a seed bank analysis on 84 plots with increasing cover of L. polyphyllus in three mountain-meadow types of the Rhön Biosphere Reserve, Germany. Seedlings from 119 species germinated from the seed bank samples, including 17 Red List species but only a few seedlings of L. polyphyllus. While the influence of L. polyphyllus on the current vegetation was visible, no effects on the seed bank were apparent. L. polyphyllus had no influence on total seed density, seed density of typical mountain-meadow species, or species numbers in the seed bank. Only the seeds of the Red List species were significantly related to the cover of L. polyphyllus. The authors conclude that the seed bank offers potential for active restoration of species-rich mountain meadows, but species absent from the seed bank have to be added by other measures.

Kristin Ludewig, Wiebke Hansen and Yves Klinger will presents these and other results from a large restoration project in the UNESCO Rhön Biosphere Reserve at the RivEM week.

On Tuesday 14 January, Jacqueline Hoppenreijs, RivEM PhD-student, will give a seminar titled “Rooting for riparian vegetation”. Jacqueline will present her plans for her PhD project during the seminar, with emphasis on her fieldwork this summer.

The seminar starts at 13:15 in room 5F416 at Karlstad University. Everyone who wants to are welcome to attend the seminar.

 

Jacqueline doing fieldwork

 

Riparian plants in the growroom at Karlstad University

Jacqueline Hoppenreijs recently joined the NRRV research group. Here she writes about her previous work and what she intends to do as a PhD student at Karlstad University:

Hej! I’m Jacqueline Hoppenreijs and I recently started my PhD in the NRRV group at Karlstad University. During my MSc, which I did at the Department of Environmental Science at Radboud University in Nijmegen (the Netherlands) and the Department of Ecology at SLU Uppsala, I worked on different species groups: plants, birds and insects and wrote two theses. The first one, with fellow student Bas van Lith, explored possibilities for bird population restoration on the Indonesian island of Java, using historical sources on bird population development and land use change over the course of a century. During the second one, I studied the importance of different man-made habitat types for pollinators in Sweden, over the course of a season.

 

Bas and I birdwatching in Rancaekek, by Fachmi Azhar Aji

 

Despite studying quite different time frames and taxa, biodiversity, ecosystem functioning and conservation have been recurring themes. Coming from the overpopulated Netherlands, I find myself very interested in the interface of human society and nature, and more specifically nature restoration, conservation efforts and their ethical aspects.

As a junior researcher at the Department of Animal Ecology & Physiology at Radboud University, I dove a bit deeper in the influence that human actions can have on the natural world. I worked in Rob Leuven’s group to identify the potential risks of invasive (alien) species in horticulture, biological control and food forestry.

As from April 2019, I’m working with Lutz Eckstein and Lovisa Lind. We’re focusing on both fundamental and applied aspects of plant ecology and I’m looking forward to unravel the mechanisms that drive plant dispersal and community composition in boreal riparian zones. Next to that, I’m excited to be part of an active education environment and the passionate group of researchers that forms the NRRV, and can’t wait to meet the rest of Karlstad’s community!

 

Vegetation sampling on Omey Island, by Joop Schaminée

Viola elatior and the two habitats used in the study: early successional floodplain meadows and late successional alluvian woodlands. Photos: Benjamin Schulz.

Benjamin Schulz, Walter Durka, Jiří Danihelka and Lutz Eckstein recently published the research paper “Differential role of a persistent seed bank for genetic variation in early vs. late successional stages” in the scientific journal PLOS ONE. In the abstract, the authors write:

“Persistent seed banks are predicted to have an important impact on population genetic processes by increasing effective population size and storing past genetic diversity. Accordingly, persistent seed banks may buffer genetic effects of disturbance, fragmentation and/or selection. However, empirical studies surveying the relationship between aboveground and seed bank genetics under changing environments are scarce. Here, we compared genetic variation of aboveground and seed bank cohorts in 15 populations of the partially cleistogamous Viola elatior in two contrasting early and late successional habitats characterized by strong differences in light-availability and declining population size. Using AFLP markers, we found significantly higher aboveground than seed bank genetic diversity in early successional meadow but not in late successional woodland habitats. Moreover, individually, three of eight woodland populations even showed higher seed bank than aboveground diversity. Genetic differentiation among populations was very strong (фST = 0.8), but overall no significant differentiation could be detected between above ground and seed bank cohorts. Small scale spatial genetic structure was generally pronounced but was much stronger in meadow (Sp-statistic: aboveground: 0.60, seed bank: 0.32) than in woodland habitats (aboveground: 0.11; seed bank: 0.03). Our findings indicate that relative seed bank diversity (i.e. compared to aboveground diversity) increases with ongoing succession and despite decreasing population size. As corroborated by markedly lower small-scale genetic structure in late successional habitats, we suggest that the observed changes in relative seed bank diversity are driven by an increase of outcrossing rates. Persistent seed banks in Viola elatior hence will counteract effects of drift and selection, and assure a higher chance for the species’ long term persistence, particularly maintaining genetic variation in declining populations of late successional habitats and thus enhancing success rates of population recovery after disturbance events.”

Read the paper here!