The mycorrhiza-mediated pathway for soil organic matter (SOM) formation and consequences for the SOM turnover under short rotation forestry
Final Report Abstract
Arbuscular (AM) and ectomycorrhizal (EM) fungi influence soil organic matter (SOM) quantity and quality using different mechanisms. We have used the land use change from arable crops to short rotation forestry (SRF) and the back-change to investigate the impact the dominating mycorrhiza type on the quantity, composition and turnover of SOM in Cambisols. Oppositely to initial expectations, even under dominant (70-80% of the fine root tips) EM poplar clones in SRF also significantly increased spore densities of AM fungi and glomalin concentrations were revealed. These might be explained (I) by the no-till management of SRF, which is known to support AM colonization in the field, and (II) by AM weeds. SRF resulted in significant increased concentrations of total fungal (18:2ω6) and AM fungal (16:1ω5) biomass in the soil microbial population, which was measured by PLFA analyses. The microbial population was controlled rather by the current than by the former vegetation, without significant long-term effects of SRF. However, SRF with poplar resulted in significant changes in the molecular chemical composition and thermal stability of SOM. The former short rotation coppice (FRC) revealed significant increased portions of alklyaromatics, phenol and lignin monomers in SOM even four years after return to tillage and annual arable crops. The impact of SRF on the total C pool varied sitespecific. EM colonization decreased the fine root decomposition of poplar with significant differences in the magnitude between different EM fungal species in an incubation experiment using litter of mycorrhizal and non-mycorrhizal fine roots. Fungal triglycerides were revealed from the EM partners and supposed to be the causal agent of hydrophobicity of EM fine roots. We conclude, that the impact of EM colonization of the vegetation on the SOM storage is mainly based on a changed litter quality and decreased fine root decomposition. Furthermore, EM colonization under SRF is combined with a rising impact of AM fungi on the soil aggregation.
Publications
- (2013) Changes in SOM under short-rotation forestry with fast-growing tree species. In: Jahrestagung Deutsche Bodenkundliche Gesellschaft, 07.-12.09.2013, Rostock
Hilke I., Henkel K., Gruner K., Barth M., Baum C., Leinweber P., Gleixner G.
- (2013) Changes in SOM under short-rotation forestry with fast-growing tree species. In: Jahrestagung Deutsche Bodenkundliche Gesellschaft, 07.-12.09.2013, Rostock. DBGPrints-Archiv; Online-Publikation; pp. 1-3
Hilke I., Henkel K., Gruner K., Barth M., Baum C., Leinweber P., Gleixner G.
