Soil depth may affect plant diversity in two apparently opposing manners: on the one hand, deeper soil may increase the available space for below-ground niche partitioning, on the other hand, soil depth may have a negative effect on plant diversity by increasing productivity and the rate of competitive exclusion. Due to the scarcity of experimental studies that actively manipulate soil depth, the conditions under which each mechanism dominates are still unclear. Here, we studied the interactive effects of soil depth with common land use practices, namely, nutrient addition, trampling by grazers and mowing on plant diversity in grasslands. We manipulated these factors in a full-factorial manner in grassland mesocosms. Soil depth had a strong positive effect on species richness under mowing, suggesting increased space for niche differentiation in deeper soils. In unmown plots, deep soils harboured a similar diversity of species as shallow soils, and our findings suggest that this effect on diversity is due to larger biomass and lower light availability on deep soils. Fertilization and trampling had no effect on diversity. Overall, our findings indicate that soil depth effects on grassland communities strongly interact with common land use practices. We therefore advocate the inclusion of soil depth effects in manipulative experiments and management plans.
Bibliographical noteFunding Information:
– We would like to thank Lorenz Henneberg, Jürgen Zebrak and Margret Ecke as well as many students mainly for their help in the establishment and maintenance of the experiment. We are very grateful to Pierre Liancourt for stimulating discussions and helpful comments on earlier versions of the manuscript as well as Eyal Ben-Hur for generously sharing his expertise on experimental design and for helpful discussion. Furthermore, we thank Christiane Fischer, Jule Mangels and Victoria Grießmeier for providing support via the central office of the Biodiversity Exploratories, Michael Owonibi and Andreas Ostrowski for managing the central data base, and Markus Fischer, Eduard Linsenmair, Dominik Hessenmöller, Daniel Prati, Ingo Schöning, François Buscot, Ernst-Detlef Schulze, Wolfgang W. Weisser and the late Elisabeth Kalko for their role in setting up the Biodiversity Exploratories project. – The work has been funded by the DFG Priority Program 1374 ‘Biodiversity-Exploratories' (DFG-Refno.) (projects TI 338/13-1, TI 338/13-2, KA 4006/1-1, KA 4006/1-2).
– The work has been funded by the DFG Priority Program 1374 ‘Biodiversity‐Exploratories' (DFG‐Refno.) (projects TI 338/13‐1, TI 338/13‐2, KA 4006/1‐1, KA 4006/1‐2).
© 2022 The Authors. Oikos published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos.
- soil depth
- species diversity
- species richness