Internships

B-WARE gives internship opportunities for BSc- and MSc-students of biology

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Internships

The applicability of zeolite minerals in nature development on calcareous poor soils?

Regeneration of Juniperus communis

Effects of altering salinity levels on biogeochemical processes and typical brackish submersed macrophytes

The applicability of zeolite minerals in nature development on calcareous poor soils?

Background

Zeolite minerals are able to bind ammonium ions (NH₄⁺) and simultaneously release cations due to their ion-exchange properties, making them promising to mitigate for the increased atmospheric nitrogen deposition (Doorn van, et al., 2021). In pilot experiments, the ammonium removal of different zeolites was tested (vulkamin, actionine, optizec) when applied to an ammonium nitrate solution (based on mean annual nitrogen deposition in the Netherlands) and to different non-calcareous nature soils. Highest ammonium removal was found two weeks after actionine and optizec application to the ammonium nitrate solution (> 80%) and the slightly buffered grassland and softwater lake soil solutions (> 50%). In addition, calcium, potassium and sodium cations were released, indicating ion exchange with ammonium. Reductions in ammonium were lower in the acidic (oak forest) and over-limed (heathland) soil solutions, due to higher cation concentrations (H⁺; Ca²⁺) which compete with ammonium ions for absorption by zeolites. Vulkamin was less effective in ammonium removal and led to raised pH of the soil solutions, which in turn stimulated organic matter mineralization or nitrification, depending on initial soil conditions. More refined research about long-term effects and field experiments are needed to evaluate whether zeolites can be used in practice as mitigation tool for the raised nitrogen deposition.

Doorn, van J., Lucassen, E.C.H.E.T., Douma, M., Roosmalen, M., Roelofs, J.G.M. & A.J.P. Smolders. Mitigating nitrogen deposition with zeolite: potential applicability for different soil types. Landschap 2021 (2): 107-115.

Research

Two long term field experiments will be started at Heerenven (Arcen) in cooperation with Het Limburgs Landschap in autumn 2022. The effects of sod cutting, zeolite type and dosis will be tested on soil chemistry and softwater vegetation (experiment 1) including the (expected) suppression of the invasive species Crassula helmsii (experiment 2). In early spring (2023) plant species will be introduced and the effects on abiotic conditions, as well as on vegetation, can be monitored.

Information

Jelmer van Doorn and Esther Lucassen
B-WARE Research Center, Radboud University Nijmegen
E.Lucassen@b-ware.eu

Regeneration of Juniperus communis

Background

Causes for the regeneration problem of juniper (Juniperus communis) in the Maasduinen area (the Netherlands) have been studied by comparing soil and plant chemistry of locations with and without regeneration (Lucassen et al., 2011). Locations with less regeneration had a relatively low soil base saturation due to acifification. The concentration of soil extractable Al, as well as the Al:Ca ratio of the soil adsorption complex, was increased up to values indicative root toxicity that hinders  the settlement of seedlings. In addition, berries developed higher N:Ca, N:P and N:K ratios accompanied by  a higher infestation with mites and a lower viability of the seeds. The results indicated that liming of the top layer will be important to improve regeneration. Furthermore, liming of the deeper soil will theoretically lead to the production of more viable seeds and also improve regeneration.

Lucassen, E.C.H.E.T., Loeffen, L., Popma, J., Verbaarschot, E., E. Remke, S, de Kort & J. Roelofs (2011). Bodemverzuring lijkt een sleutelrol te spelen in het verstoorde verjongingsproces van jeneverbes (Juniperus communis). De Levende Natuur 112 (6): 235-239.

Research

In 2014 a field experiment was conducted in cooperation with Limburgs Landschap in Boshuizerbergen (Venray). The quality of the deeper soil layer was improved by adding dolocal (Ca, Mg) and patentkali (K) to the deeper soil layer (0-1 m) near 10 female trees. The quality of the needles and berries have been monitored on a yearly base (and compared to 10 control trees). Within two years, liming of the deep soil layer led to decreased N and increased Ca and Mg concentrations in berries and needles. However, P and K concentrations strongly decreased during extreme dry summers in 2018, 2019 and 2020. During the last two years several seedlings have developed in Boshuizerbergen for the first time. 
The first aim of this study is to test the viability of the seeds by performing Tetrazolium tests. We suspect that the lower N:Ca and N:P ratio of the berries, as present in 2021, will lead to a higher viability of the seeds. The second aim of the study is to test the (interactive) effect of a higher P and K dosis to the deep soil layer on the quality and viability of the seeds.  For this, 30 trees will be selected in autumn 2022.

Information

Jelmer van Doorn and Esther Lucassen
B-WARE Research Center, Radboud University Nijmegen
E.Lucassen@b-ware.eu