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69 results on '"Clarholm, M."'

7. Soil protistology rebooted: 30 fundamental questions to start with

Author

Geisen, S., Mitchell, E.A.D., Wilkinson, D.M., Adl, S., Bonkowski, M., Brown, M.W., Fiore-Donno, A.M., Heger, T.J., Jassey, V.E.J., Krashevska, V., Lahr, D.J.G., Marcisz, K., Mulot, M., Payne, R., Singer, D., Anderson, O.R., Charman, D.J., Ekelund, F., Griffiths, B.S., Rønn, R., Smirnov, A., Bass, ´D., Belbahri, L., Berney, C., Blandenier, Q., Chatzinotas, Antonis, Clarholm, M., Dunthorn, M., Feest, A., Fernández, L.D., Foissner, W., Fournier, B., Gentekaki, E., Hájek, M., Helder, J., Jousset, A., Koller, R., Kumar, S., La Terza, A., Lamentowicz, M., Mazei, Y., Santos, S.S., Seppey, C.V.W., Spiegel, F.W., Walochnik, J., Winding, A., Lara, E., Geisen, S., Mitchell, E.A.D., Wilkinson, D.M., Adl, S., Bonkowski, M., Brown, M.W., Fiore-Donno, A.M., Heger, T.J., Jassey, V.E.J., Krashevska, V., Lahr, D.J.G., Marcisz, K., Mulot, M., Payne, R., Singer, D., Anderson, O.R., Charman, D.J., Ekelund, F., Griffiths, B.S., Rønn, R., Smirnov, A., Bass, ´D., Belbahri, L., Berney, C., Blandenier, Q., Chatzinotas, Antonis, Clarholm, M., Dunthorn, M., Feest, A., Fernández, L.D., Foissner, W., Fournier, B., Gentekaki, E., Hájek, M., Helder, J., Jousset, A., Koller, R., Kumar, S., La Terza, A., Lamentowicz, M., Mazei, Y., Santos, S.S., Seppey, C.V.W., Spiegel, F.W., Walochnik, J., Winding, A., and Lara, E.

Abstract

Protists are the most diverse eukaryotes. These microbes are keystone organisms of soil ecosystems and regulate essential processes of soil fertility such as nutrient cycling and plant growth. Despite this, protists have received little scientific attention, especially compared to bacteria, fungi and nematodes in soil studies. Recent methodological advances, particularly in molecular biology techniques, have made the study of soil protists more accessible, and have created a resurgence of interest in soil protistology. This ongoing revolution now enables comprehensive investigations of the structure and functioning of soil protist communities, paving the way to a new era in soil biology. Instead of providing an exhaustive review, we provide a synthesis of research gaps that should be prioritized in future studies of soil protistology to guide this rapidly developing research area. Based on a synthesis of expert opinion we propose 30 key questions covering a broad range of topics including evolution, phylogenetics, functional ecology, macroecology, paleoecology, and methodologies. These questions highlight a diversity of topics that will establish soil protistology as a hub discipline connecting different fundamental and applied fields such as ecology, biogeography, evolution, plant-microbe interactions, agronomy, and conservation biology. We are convinced that soil protistology has the potential to be one of the most exciting frontiers in biology.

Published
2017

12. Trophic relationships in the soil microfood-web: predicting the response to a changing global environment

Author

Wardle, D.A., Verhoef, H.A., Clarholm, M., and Animal Ecology

Abstract

In this article, we evaluate how global environmental change may affect microfood-webs and trophic interactions in the soil, and the implications of this at the ecosystem level. First we outline how bottom-up (resource control) and top-down (predation-control) forces regulate food-web components. Food-web components can respond either positively or negatively to shifts in NPP resulting from global change, thus creating difficulties in developing general principles about the response of soil biota to global change phenomena. We also demonstrate that top-down effects can be important in soil food-webs, creating negative feed-backs which may partially counter bottom-up effects. Secondly, we determine how soil food-webs and the processes they regulate respond to various global change phenomena. Enhanced atmospheric CO

Published
1998

16. Fungi, bacteria and protozoa in soil from four arable cropping systems

Author

Schnürer, Johan, Clarholm, M., Rosswall, T., Schnürer, Johan, Clarholm, M., and Rosswall, T.

Abstract

The effects of four cropping systems on soil microorganisms were investigated during 3 years. The cropping systems were B0, barley without nitrogen fertilizers; B120, barley with 120 kg N ha-1 year-1; GL, grass ley receiving 200 kg N ha-1 year-1; and LL, lucerne ley without nitrogen fertilizer additions. At samplings in September during three consecutive years no differences were found between treatments. Total fungal lengths ranged between 0.7 and 2.0 × 103 m and bacterial numbers between 3.5 and 7.2 × 109 g-1 dry wt. soil. Twenty samplings over 3 years in B120 and in GL indicated higher numbers of bacteria and protozoa during the growing season, except for periods with moisture stress. No clear seasonal trends were found for the fungi. When comparing mean values for the 20 samplings, the grass ley contained significantly (P < 0.05) higher numbers of amoebae. Means of the bacterial numbers and biomass, total and FDA-active hyphal lengths were also higher or equal (FDA-active hyphae) but not significantly so. Seventy-nine per cent of the bacterial biomass and 73% of the total fungal lengths were found in the top soil, where also 85% of the oxygen was consumed.

Published
1986
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20. Wood ash to counteract potential phosphorus and potassium limitations in a Norway spruce forest subjected to air pollution

Author

Clarholm, M.

Subjects
AIR pollution, FORESTS & forestry, FUNGI, NORWAY spruce, POTASSIUM
Abstract

Bioassays using 32P and 86Rb uptake rates of fine roots were applied in a field trial with spruce in southwestern Sweden designed to study air pollution and methods of counteracting potential mineral nutrient imbalances. Phosphorus deficiencies were indicated in the control, a treatment amended with granulated ash and anirrigated treatment, while no K deficiencies were found. The contradiction between the obtained results and reported fertilizer effects on tree growth is discussed. High P uptake rates of fine roots were related to low P/C of the microbial biomass in the humus. The bioassay thus described the P situation not for the trees, but for the microbial biomass of which the mycorrhizal fungi, forming the mantle of roots, is part. After five years the 32P uptake rate of fine roots was significantly lower and the microbial P content higher in the humus layer of the ash treatment compared to the control. [ABSTRACT FROM AUTHOR]

Published
1998

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