Land use in mountain grasslands alters drought response and recovery of carbon allocation and plant-microbial interactions

1. Mountain grasslands have recently been exposed to substantial changes in land-use and climate and in the near future will likely face an increased frequency of extreme droughts. To date is not known how the drought responses of carbon (C) allocation, a key process in the C cycle, are affected by land-use changes in mountain grassland. 2. We performed an experimental summer drought on an abandoned grassland and a traditionally managed hay meadow and traced the fate of recent assimilates through the plant-soil continuum. We applied two 13CO2 pulses, at peak drought and in the recovery phase shortly after rewetting. 3. Drought decreased total C uptake in both grassland types and led to a loss of aboveground carbohydrate storage pools. The belowground C allocation to root sucrose was enhanced by drought, especially in the meadow, which also held larger root carbohydrate storage pools. 4. The microbial community of the abandoned grassland comprised more saprotrophic fungal and Gram (+) ba...

1. 山地草原（Mountain grasslands）近年来正经历土地利用与气候的显著变化，且在不久的将来极可能面临极端干旱事件频率升高的挑战。目前尚不清楚，碳循环（carbon cycle）的核心过程之一——碳（C）分配对干旱的响应，如何受山地草原土地利用变化的影响。
2. 本研究针对弃耕草原与传统管理的干草甸开展夏季干旱胁迫实验，并通过植物-土壤连续体（plant-soil continuum）示踪近期同化物的去向。我们分别在干旱峰值期以及复湿后不久的恢复阶段，施加两次13CO2脉冲标记。
3. 干旱胁迫降低了两类草原的总碳吸收量，并导致地上碳水化合物储存库的损耗。干旱胁迫促进了地下碳向根系蔗糖的分配，这一效应在干草甸中尤为显著，且干草甸的根系碳水化合物储存库本身也更大。
4. 弃耕草原的微生物群落中，腐生真菌与革兰氏阳性（Gram (+)）菌的占比更高……