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.

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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.

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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.

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.

Lutz Eckstein, professor at Karlstad University, together with Yves Klinger, David Horlemann, Annette Otte and Kristin Ludewig recently published the paper Germination of the invasive legume Lupinus polyphyllus depends on cutting date and seed morphology in the journal NeoBiota. The paper is accessible open access on the journal website, or you can read a summary of the paper below:

In semi-natural grasslands, mowing leads to the dispersal of species that have viable seeds at the right time. For invasive plant species in grasslands, dispersal by mowing should be avoided, and information on the effect of cutting date on the germination of invasive species is needed. We investigated the germination of seeds of the invasive legume Lupinus polyphyllus Lindl. depending on the cutting date. We measured seed traits associated with successful germination that can be assessed by managers for an improved timing of control measures. Germination patterns were highly asynchronous and differed between seeds cut at different dates. Seeds cut early, being green and soft, tended to germinate in autumn. Seeds cut late, being dark and hard, were more prone to germinate the following spring, after winter stratification. This allows the species to utilize germination niches throughout the year, indicating a bet-hedging strategy.

Seed color and the percentage of hard seeds were good predictors of germination percentage. Managers should prevent the species from producing black and hard seeds, while cutting plants carrying green and soft seeds appears less problematic. Furthermore, germination patterns differed between experiments in climate chambers and in the common garden, mainly because germination of dormant seeds was lower in climate chambers. We propose that more germination experiments under ambient weather conditions should be done, as they can give valuable information on the germination dynamics of invasive species.

On Tuesday 12 November, Lutz Eckstein, NRRV-Professor, will give a seminar titled “Phenology of invasive species: what drives the flowering and seed set of Garden Lupine along a latitudinal gradient?” The seminar starts at 13:15 in room 5F416, everyone who wants to are welcome to attend the seminar.

The paper led by scientists of the Department of Engineering and Chemical Sciences, Karlstad University, was co-authored by Lutz Eckstein, professor of biology at the Department of Environmental and Life Sciences.

He writes about their work:

“Sweden has about 28 million hectares of forests, and pine trees constitute 40% of the total standing volume. Since the country is the world’s second largest exporter of pulp, paper and wood products, a total of 400 million containerized tree seedlings are produced by Swedish forest nurseries to restock forests each year. However, intensive annual forest harvests remove essential soil nutrients, which may cause problems for forest productivity.

In Sweden, container-grown seedlings are dominantly produced in peat and peat-based growth media. Peat-based substrates have many advantages such as long-term drainage ability, good aeration for tree seedling roots, good fertilizer absorbance and release capability. However, peat-based media are considered non-sustainable as their extraction have adverse environmental impacts. Therefore, sustainable approaches towards forest production and plantation management are urgently needed.

Therefore, the aim of this paper was to study the effects of hydrochar, derived from paper mill biosludge, on growth, quality, mycorrhizal associations and nutrient/heavy metal uptake of pine tree seedlings. We analyzed whether effects varied significantly between hydrochar forms (powder or pellets) or hydrochar proportions mixed with peat (10% or 20% hydrochar v/v). The effects of hydrochar addition on pine tree seedling was evaluated under three fertilization regimes (no fertilizer, 50% fertilizer and 100% fertilizer). We hypothesized that the growth, quality and mycorrhizal colonization of pine tree seedlings grown in substrate mixed with hydrochar would improve. We also expected pine tree seedlings grown with hydrochar to require less fertilizer to achieve similar or higher growth, mycorrhizal colonization and associated nutrient uptake relative to seedlings grown without hydrochar but with optimum rates of fertilizer (100% fertilizer). To our knowledge, this current study is the first paper to explore the potentials of hydrochar powder and pellets for being used as a growing media component in production of containerized pine tree seedlings.

Application of hydrochar had positive or neutral effects on shoot biomass and stem diameter compared with control seedlings (without hydrochar) under tested fertilizer levels. Analysis of the natural logarithmic response ratios (LnRR) of quality index and nutrient and heavy metal uptake revealed that application of 20% (v/v) hydrochar powder or pellet with 50% fertilizer resulted in same quality pine seedlings with similar heavy metal (Cu, Ni, Pb, Zn and Cr) and nutrient (P, K, Ca and Mg) contents as untreated seedlings supplied with 100% fertilizer. Colonization percentage by ectomycorrhizae significantly increased when either forms of hydrochar were applied at a rate of 20% under unfertilized condition. The results of this study implied that application of proper rates of hydrochar from biosludge with adjusted levels of liquid fertilizer may reduce fertilizer requirements in pine nurseries.”

Read the paper for free here! 

Yves P. Klinger, Sarah Harvolk-Schöning, Lutz Eckstein, Wiebke Hansen, Annette Otte and Kristin Ludewig recently published the paper ”Applying landscape structure analysis to assess the spatio-temporal distribution of an invasive legume in the Rhön UNESCO Biosphere Reserve” in the journal Biological Invasions.

Lutz Eckstein, Professor in Biology at Karlstad University, writes about their work:

“We applied a combination of aerial mapping and GIS-based landscape analysis to study the invasion of the legume, Lupinus polyphyllus, in the Rhön UNESCO Biosphere Region as a case. We assessed the changes in lupine distribution between 1998 and 2016 in a strictly protected part of the Biosphere Region by means of landscape structure analysis. The area invaded by L. polyphyllus doubled from 1998 to 2016. The number of lupine stands decreased by 25%, but average stand size increased by 300%. In 2016, large and well-connected mesic grasslands that were situated close to roads were more heavily invaded than small and remote wet grasslands. Our results show that landscape composition plays an important role for the spread of invasive plants. Specifically, invasive stand characteristics, such as stand size, form, and connectivity, are crucial for driving the invasion process. Therefore, in addition to landscape composition, invasive stand characteristics should be included in the planning of conservation measures. Overall, aerial mapping combined with landscape analysis provides a cost-effective and practical tool for landscape managers to prioritize invasive control measures.”

Access the paper here, or contact any of the authors.

För ungefär en månad sedan uppmärksammade vi en forskningsartikel som handlade om hur grågåsen genom sin spillning är viktig för växters spridning på skärgårdsöar i Östersjön (läs inlägget här). Lutz Eckstein, Professor i NRRV, är medförfattare på artikeln.

Nu har forskningen fått stort mediegenomslag, och uppmärksammats av bland annat Sveriges Radio (lyssna på ett inslag där Lutz berättar om studien), Aftonbladet, Svenska Dagbladet, Ny Teknik samt en mängd lokaltidningar (Smålandsposten, Kristianstadsbladet, Bohuslänningen, Enköpingsposten, Borås tidning, Uppsala nya tidning, Katrineholms-Kuriren m.fl.).

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 (ф_ST = 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!

 

Dirk Hattermann (Justus Liebig University Giessen), Markus Bernhardt-Römermann (Friedrich Schiller University Jena), Annette Otte (Justus Liebig University Giessen) and Lutz Eckstein (Karlstad University) recently published the paper “New insights into island vegetation composition and species diversity – Consistent and conditional responses across contrasting insular habitats at the plot-scale” in the scientific journal PLOS ONE.

In the abstract the authors write:

“Most island-ecology studies focus on the properties of entire island communities, thus neglecting species-environment relationships operating at the habitat-level. Habitat-specific variation in the strength and sign of these relationships will conceal patterns observed on the island scale and may preclude a mechanistic interpretation of patterns and processes. Habitat-specific species-environment relationships may also depend on the descriptor of ecological communities. This paper presents a comprehensive plot-based analysis of local vegetation composition and species diversity (species richness and species evenness) of (i) rocky shore, (ii) semi-natural grassland and (iii) coniferous forest habitats in three Baltic archipelagos in Sweden. To identify differences and consistencies between habitats and descriptors, we assessed the relative contributions of the variable-sets “region”, “topography”, “soil morphology”, “soil fertility”, “soil water”, “light availability”, “distance” and “island configuration” on local vegetation composition, species richness and species evenness. We quantified the impact of “management history” on the descriptors of local grassland communities by a newly introduced grazing history index (GHI). Unlike species diversity, changes in vegetation composition were related to most of the variable-sets. The relative contributions of the variable-sets were mostly habitat-specific and strongly contingent on the descriptor involved. Within each habitat, richness and evenness were only partly affected by the same variable-sets, and if so, their relative contribution varied between diversity proxies. Across all habitats, soil variable-sets showed highly consistent effects on vegetation composition and species diversity and contributed most to the variance explained. GHI was a powerful predictor, explaining high proportions of variation in all three descriptors of grassland species communities. The proportion of unexplained variance was habitat-specific, possibly reflecting a community maturity gradient. Our results reveal that species richness alone is an incomplete representation of local species diversity. Finally, we stress the need of including habitat-based approaches when analyzing complex species-environment relationships on islands.”

You can access the paper here.