Autor:innen:
Doreen Fleck | Leibniz University Hannover | Germany
Dr. Liesbeth van den Brink | Eberhard Karls University Tübingen | Germany
Diana Boy | Leibniz University Hannover | Germany
Dr. Harald Neidhardt | Eberhard Karls University Tübingen | Germany
Dr. Leopold Sauheitl | Leibniz University Hannover | Germany
Dr. Francisco Javier Matus | Universidad de la Frontera | Chile
Prof. Dr. Yvonne Oelmann | Eberhard Karls University Tübingen | Germany
Prof. Dr. Katja Tielbörger | Eberhard Karls University Tübingen | Germany
Prof. Dr. Georg Guggenberger | Leibniz University Hannover | Germany
Dr. Jens Boy | Leibniz University Hannover
Abiotic and biotic processes strongly influence each other in soils and thereby also substantially change ecosystem parameters and the shape of the earth's surface. Of particular importance is the biogenic mineral weathering by plants and their symbiotic partners, namely the mycorrhizae. The fungi foster directed nutrient mobilization to balance the nutrient supply on ecosystem level in the long-term with the help of the enormous energetic potential of the photoassimilate flux provided by plants. In a previous study along two aridity gradients ranging from Mediterranean to hyper-arid conditions in Chile and Israel, we surprisingly found a proportional increase in biogenic weathering with increasing aridity. A finding we explained by the increasing absence of soil solution and thus an increasing importance of soil solution-independent biogenic weathering for general nutrient supply. To clarify whether this proportional increase in biogenic weathering is ubiquitous or limited to habitats where droughts are more frequent and the microbial community possibly better adapted to drought is phenotypically independent, i.e. open to any symbiosis, or rather represents an evolutionary gained adaptive capacity of mycorrhizal partners to their respective sites. We installed rainout shelter that retain 75% of precipitation at two sites that differ greatly in mean annual precipitation but not in basic geological features. This corresponds to the drier conditions of the subsequent gradient site, in order to subject the symbiotic community of an ecosystem to a two-year drought treatment. We buried bags with freshly broken mineral particles of biotite (Mg, K), muscovite (K) and apatite (P) below the rainout shelters and adjacent control plots and subsequently analyzed the hyphal growth on the mineral surfaces. We found that colonization by symbionts at the arid end of the gradient, was much less reduced by drought than at the wetter site. At the drier end, the mycorrhizal symbiosis better compensates for the reduced soil solution with an increase in their biogenic weathering compared to that at the wetter end of the gradient. This suggests a targeted co-evolution between fungi and partner at arid sites, which leads to increased biogenic weathering and shows that a simple transfer of this functional trait by means of space for time substitution is not possible.