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Data from: Drought history affects grassland plant and microbial carbon turnover during and after a subsequent drought event

Citation

Fuchslueger, Lucia et al. (2017), Data from: Drought history affects grassland plant and microbial carbon turnover during and after a subsequent drought event, Dryad, Dataset, https://doi.org/10.5061/dryad.2t3sn

Abstract

Drought periods are projected to become more severe and more frequent in many European regions. While effects of single strong droughts on plant and microbial carbon (C) dynamics have been studied in some detail, impacts of recurrent drought events are still little understood. We tested whether the legacy of extreme experimental drought affects responses of plant and microbial C and nitrogen (N) turnover to further drought and rewetting. In a mountain grassland we conducted a 13C pulse-chase experiment during a naturally occurring drought and rewetting event in plots previously exposed to experimental droughts, and in ambient controls. After labelling we traced 13C below-ground allocation and incorporation into soil microbes using phospholipid fatty acid (PLFAs) biomarkers. Drought history had no effects on the standing shoot and fine root plant biomass. However, plants with experimental drought history displayed decreased shoot N concentrations, and increased fine root N concentrations relative to those in ambient controls. During the natural drought plants with drought history assimilated and allocated less 13C below-ground; moreover, fine root respiration was reduced and not fuelled by fresh C compared to plants in ambient controls. Regardless of drought history microbial biomass remained stable during natural drought and rewetting. Although microbial communities initially differed in their composition between soils with and without drought history, they responded to the natural drought and rewetting in a similar way: gram-positive bacteria increased, while fungal and gram-negative bacteria remained stable. In soils with drought history a strongly reduced uptake of recent plant-derived 13C in microbial biomarkers was observed during the natural drought, pointing to a smaller fraction of active microbes or to a microbial community that is less dependent on plant C. Synthesis: Drought history can induce changes in above- versus below-ground plant N concentrations and affect the response of plant C turnover to further droughts and rewetting by decreasing plant C uptake and below-ground allocation. Drought history does not affect the responses of the microbial community to further droughts and rewetting, but alters microbial functioning, particularly the turnover of recent plant-derived carbon, during and after further drought periods.

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