Subsurface earthworm casts can be important soil microsites specifically influencing the growth of grassland plants

• DOI: 10.1007/s00374-013-0808-4
• Publication Date: 2013-05-01T09:04:59Z
• Authors: Johann G. Zaller; Katharina F. Wech...; Markus Gorfer; Patrick Hann; Thomas Frank; Wolfgang Wanek; Thomas Drapela
• Keywords: Grassland ecology; LUMBRICUS-RUBELLUS; Astronomy; CALCAREOUS GRASSLAND; DIVERSITY; Aboveground-belowground interactions; Soil Science; Polymerase chain reaction (PCR); Microbiology; BIOMASS; ROOT; 1030 Physics; 1030 Physik; 401902 Soil science; 106026 Ecosystem research; Original Paper; ARBUSCULAR-MYCORRHIZAL FUNGI; Vesicular-arbuscular mycorrhizal fungi (AMF); Mesocosm experiment; NUTRIENT PATCHES; 04 agricultural and veterinary sciences; Astronomie; 15. Life on land; 401902 Bodenkunde; NITROGEN; Plant-animal-fungi interaction; 106026 Ökosystemforschung; 0401 agriculture, forestry, and fisheries; ELEVATED CO2; Agronomy and Crop Science; EARLY SUCCESSION

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 (four Glomus taxa) 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 caliginosa vs. 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-1 soil) 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.