Drought intensity alters productivity, carbon allocation and plant nitrogen uptake in fast versus slow grassland communities

作者：Natalie J. Oram, Johannes Ingrisch, Richard D. Bardgett, Fiona Brennan, Georg Dittmann, Gerd Gleixner, Paul Illmer, Nadine Praeg, Michael Bahn · 发表于：Journal of Ecology · 年份：2023 · DOI：10.1111/1365-2745.14136 · 被引用次数：47 · 研究领域：Soil Carbon and Nitrogen Dynamics、Ecology and Vegetation Dynamics Studies、Plant Water Relations and Carbon Dynamics

Abstract Grasslands face more frequent and extreme droughts; yet, their responses to increasing drought intensity are poorly understood. Increasing drought intensity likely triggers abrupt shifts (thresholds) in grassland ecosystem functioning which can implicate recovery trajectories. Here, we determined how drought intensity affects plant productivity, and plant–soil carbon (C) and nitrogen (N) cycling. We exposed model grassland plant communities with contrasting resource acquisition strategies (a fast‐ vs a slow‐strategy plant community), to a gradient of drought intensity. The drought gradient ranged from well‐watered to severely water‐limited conditions. We identified thresholds of plant community productivity (above‐ground biomass) at peak drought and 2 months after re‐wetting, and measured net ecosystem exchange and ecosystem respiration of C throughout the drought and recovery phases. At peak drought and 1 week after re‐wetting, we traced recently acquired C from plants to the soil and into microbial biomass and fatty acids using 13 C pulse labelling, and measured plant and soil N. At peak drought, slow‐strategy plant communities were more drought resistant than fast‐strategy communities, as the threshold in plant productivity occurred at a higher drought intensity for the slow‐ than the fast‐strategy community. Shortly after re‐wetting, microbial uptake of recent plant‐assimilated C increased with increasing past drought intensity, coinciding with an increase in soi...