Paul Henning Krogh

Soil food web structure after wood ash application

Research output: Contribution to conferencePosterResearch

    Louise Hindborg Mortensen, Københavns Universitet,
  • Jiayi Qin
  • Carla Cruz-Paredes, Biologisk Institut, KU, Denmark
  • Paul Henning Krogh
  • Rasmus Kjøller, Københavns Universitet, Mette Vestergård, Københavns Universitet, Flemming Ekelund, KU, Biologisk Institut, DenmarkRegin Rønn, KU, Biologisk Institut, Denmark
In 2006, the European Council established a mandatory target of 20 % renewable energy of consumption by 2020. Part of the replacement is burning biomass for heating and electricity. ~ Whole tree biomass harvesting for biofuel combustion intensifies removal of nutrients from the by applying ash from the combustion back to the system and thus recycle the besides being rich in inorganic nutrients, ash is also very alkaline and contains heavy metals.

The ASHBACK project ( is a cooperation between three Danish universities other research institutions and stake-holders that aims to investigate the consequences of returning wood ash to biofuel producing coniferous forest. We that the change in pH and increased availability of nutrients after ash application to forest floor can facilitate an increase in the bacteria to fungi ratio with possible effects for the soil food by applying ash of different concentrations to experimental plots in a coniferous forest the soil will be collected with varying intervals and subsequently analyzed.

The food web included several trophic levels; bacteria/fungi, protozoa, nematodes, enchytraeids and microarthropods and arthropods. Results from 2014 indicated that bacteria and protozoa were stimulated in the uppermost soil layer (0-3 cm) two months ash application, whereas the enchytraeids seemed to be slightly negatively affected. Generally, nematodes also appeared to be negatively affected, although it differed between feeding groups. On the higher trophic levels, no effect was observed.

The 2015 results, 14 months after ash application, showed a strikingly similar picture to the 2014 results, as seen on for "2 months (2014) and 14 months (2015) after ash application". Bacteria and protozoa were still stimulated by ash in the top soil layer. Generally, the nematodes seemed to be slightly negatively affected, however the bacteria feeding nematodes a bit less so. The effects had not yet transferred to the lower soil layer (3-6 cm) at the site. Sampling in 2016 and 2017 will clarify the variability of both indirect effects of wood ash application to the terrestrial food web of a coniferous forest.
Original languageEnglish
Publication year2 Mar 2016
Number of pages1
Publication statusPublished - 2 Mar 2016
EventSoil food webs: Linking structure, energy flux and function - Humboldt-Universität zu Berlin, Berlin, Germany
Duration: 2 Mar 20164 Mar 2016


WorkshopSoil food webs: Linking structure, energy flux and function
LocationHumboldt-Universität zu Berlin

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