Non-vascular plants as a food source for litter-dwelling Collembola: Field evidence

Non-vascular plants such as mosses, lichens and especially microalgae are widespread in terrestrial ecosystems, but their contribution in the nutrient cycling and energy budget of soil food webs is generally neglected. Despite a relatively low total biomass, soil microalgae can be very productive and contribute to the diet of many soil decomposers such as Collembola. Using 15N/14N ratios we showed that phycophagy is of particular importance for Collembola in extreme habitats like rock surfaces, or seasonally during the wintertime. In such situations, non-vascular plants can represent the major part of the diet of Collembola. In a temperate spruce forest partial phytophagy was observed for epigeic collembolan species. These species account for about half of the total biomass of litter-dwelling springtails. Experimental blackout of the forest floor affected population density and species richness of Collembola along with their δ15N values, confirming the importance of soil microalgae for maintaining the structure of collembolan communities. These results support the emerging view that soil phototrophic microorganisms should be considered an important channel for nutrient cycling in soil communities.