Paul Henning Krogh

Soil food web structure after wood ash application

Research output: Contribution to conferencePosterResearch

    L. H. Mortensen, Unknown
  • J. Qin
  • Paul Henning Krogh
  • M. Vestergård, UnknownF. Ekelund, Regin Rønn, Terrestrisk Økologi, Denmark
In 2006, the European Council established a mandatory target of 20 % renewable energy of the total energy consumption by 2020. Part of the replacement is burning biomass for heating and electricity instead of fossil fuels. Whole-tree biomass harvesting for biofuel combustion intensifies removal of nutrients from the ecosystem. This can be partly mitigated by applying ash from the combustion back to the system and thus recycle the nutrients. However, 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 hypothesize that the change in pH and increased availability of nutrients after ash application to the forest floor can facilitate an increase in the bacteria to fungi ratio with possible cascading effects for the soil food web structure. This is tested by applying ash of different concentrations to experimental plots in a coniferous forest. During the course of the project soil samples will be collected with varying intervals and subsequently analyzed.
The food web analysis includes several trophic levels; bacteria/fungi, protozoa, nematodes, enchytraeids, microarthropods and arthropods. The initial results indicate that bacteria and protozoa are stimulated in the uppermost soil layer (0-3 cm) two months after ash application, whereas the enchytraeids are negatively affected. Generally, nematodes also appear to be negatively affected, although it differs slightly between feeding groups. The effects have not yet transferred to the lower soil layer (3-6 cm) at the site. On the higher trophic levels, we have not seen a direct effect thus far. Further sampling during the coming years will clarify the variability of both direct and indirect effects of wood ash application to a coniferous forest.
Original languageEnglish
Publication year3 Dec 2014
Publication statusPublished - 3 Dec 2014
EventGlobal Soil Biodiversity Initiative (GSBI): Assessing soil biodiversity and its role for ecosystem services - Palais des Congrès, Dijon, Dijon, France
Duration: 2 Dec 20146 Dec 2014


ConferenceGlobal Soil Biodiversity Initiative (GSBI)
LocationPalais des Congrès, Dijon

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