Steinauer, K. | Search bioRxiv

bioRxiv2023

Soil legacies of extreme droughts enhance the performance of invading plants

Extreme droughts can weaken the biotic resistance of native plant communities against the establishment of invading plants. However, we know little about the underlying mechanisms. Using a plant-soil feedback approach, we tested how an extreme drought event alters the soil-mediated biotic resistance of resident native plant communities against invading plant species from native and non-native ranges, namely non-resident natives, native range-expanders, and alien plants. We show that all three types of invading plants performed better in soils with a legacy of extreme drought independent of resident native plant diversity. Path models revealed that extreme drought effects on non-resident natives were mediated by the root biomass of resident native plants and endophytic fungal pathogens during drought, whereas alien plant performance was mediated only via the root biomass of resident native plants also during drought. Our results highlight that the performance of resident native plants during extreme drought and subsequent effects on soil fungi determine the performance of invading plants from native and non-native origins after extreme droughts.

ecology↗

bioRxiv2020

Persistence of plant-mediated microbial soil legacy effects in soil and inside roots

Plant-soil feedbacks are shaped by microbial legacies previous plants leave in the soil. We tested the persistence of such soil legacies after subsequent colonization by the same or other plant species, and whether the microbiome created by the previous plant explains current plant growth. Legacies of previous plants were detectable in soil fungal communities several months after their removal while concomitantly the effect of the current plant amplified in time. Remarkably, bacterial legacies faded away rapidly in the soil and bacterial communities were selected strongly by plant currently growing in the soil. Both fungal and bacterial legacies wrought by the previous plant were conserved inside the root endophytic compartment of the current plant and these endophytes affected significantly the plant growth. Hence, microbial soil legacies present at the time of plant establishment play a vital role in shaping plant growth even as the composition gradually changes in the soil after subsequent plant colonization, as they are taken up as endophytes in the plant. This suggests that plant-soil feedbacks may be partly mediated by a relatively stable endophytic community acquired in early ontogeny while the effects of previous plants detected on soil microbiomes vary between organisms studied. We further show that plants growing in their own soils harbor different endophytic microbiomes than plants growing in soils with legacy of other plants and that especially grasses are sensitive to species specific fungal pathogens while all plant species have less endophytic Streptomycetes when growing in their own soil. In conclusion, we show that soil legacies wrought by previous plants can remain present in the soils and inside the roots for months, even when subsequent plants colonize the soil and that these legacies also substantially modulate the plant growth.

ecology↗