Water level and seasonality drive different aspects of fine-root trait variation in rewetted fen soil

Abstract

Background and aims Drained peatlands are being rewetted to restore a variety of important ecosystem services and functions. Yet, the effect of realized groundwater level on fine-root traits and plant functioning is inconclusive so far. The aim of this study was to investigate fine-root traits and plant functioning at surface near groundwater levels on peat soil aiming at detecting drivers of intraspecific trait variation and coordination using plant economics concepts. Methods The study was conducted on nine fen soil lysimeters covered with populations of Phalaris arundinacea . We investigated fine-root traits and aboveground productivity in response to an applied groundwater gradient and seasonality over two years. Trait coordination was examined using redundancy analysis. Results Fine-root average diameter and mycorrhizal colonization decreased with increasing groundwater level while root tissue density increased, and specific root length decreased at the end of the growing season. Productivity increased linearly with the groundwater level in the first year and reached an optimum at 9.5 cm below surface in the second. Overall trait coordination was affected by groundwater level as well as seasonality. Conclusion Our findings suggest that distinct fine-root traits and corresponding economic functions of Phalaris arundinacea vary with either groundwater level or seasonal shifts in rewetted peatlands with consequences for overall trait coordination.

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