title: Subsurface earthworm casts can be important soil microsites specifically influencing the growth of grassland plants.
abstract: Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45 l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (fourGlomustaxa) affect the biomass production of 11 grassland plant species comprising the three functional groups grasses, forbs, and legumes, (2) different ecological groups of earthworms (soil dwellers-Aporrectodea caliginosavs. vertical burrowers-Lumbricus terrestris) alter potential influences of soil microsites (i.e., four earthworms × two subsurface microsites × two AMF treatments). Soil microsites were artificially inserted in a 25-cm depth, and afterwards, plant species were sown in a regular pattern; the experiment ran for 6 months. Our results show that minute amounts of subsurface casts (0.89 g kg-1soil) decreased the shoot and root production of forbs and legumes, but not that of grasses. The presence of earthworms reduced root biomass of grasses only. Our data also suggest that subsurface casts provide microsites from which root AMF colonization can start. Ecological groups of earthworms did not differ in their effects on plant production or AMF distribution. Taken together, these findings suggest that subsurface earthworm casts might play a role in structuring plant communities by specifically affecting the growth of certain functional groups of plants.
authors.affiliation: Institute of Zoology, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences, Vienna, Gregor Mendel Straße 33, 1180 Vienna, Austria.
authors.forename: Johann G
authors.initials: JG
authors.lastname: Zaller
authors.affiliation: Institute of Zoology, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences, Vienna, Gregor Mendel Straße 33, 1180 Vienna, Austria ; Bio Forschung Austria, Eßlinger Hauptstraße 132-134, 1220 Vienna, Austria.
authors.forename: Katharina F
authors.initials: KF
authors.lastname: Wechselberger
authors.affiliation: Department of Applied Genetics und Cell Biology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190 Vienna, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Gorfer
authors.affiliation: Bio Forschung Austria, Eßlinger Hauptstraße 132-134, 1220 Vienna, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hann
authors.affiliation: Institute of Zoology, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences, Vienna, Gregor Mendel Straße 33, 1180 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Frank
authors.affiliation: Department of Terrestrial Ecosystem Research, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wanek
authors.affiliation: Institute of Zoology, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences, Vienna, Gregor Mendel Straße 33, 1180 Vienna, Austria ; Research Institute of Organic Agriculture (FiBL), Seidengasse 33-35, 1070 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Drapela
keywords: Aboveground–belowground interactions; Grassland ecology; Mesocosm experiment; Plant–animal–fungi interaction; Polymerase chain reaction (PCR); Vesicular-arbuscular mycorrhizal fungi (AMF)