The supply of soil respiration with recent photoassimilates is an important and fast pathway for respiratory loss of carbon (C). To date it is unknown how drought and land-use change interactively influence the dynamics of recent C in soil respired CO2. In an in situ common-garden experiment, we exposed soil-vegetation monoliths from a managed and a nearby abandoned mountain grassland to an experimental drought. Based on two 13CO2 pulse-labelling campaigns, we traced recently assimilated C in soil respiration during drought, rewetting and early recovery. Independent of grassland management, drought reduced the absolute allocation of recent C to soil respiration. Rewetting triggered a respiration pulse, which was strongly fueled by C assimilated during drought. In comparison to the managed grassland, the abandoned grassland partitioned more recent C to belowground respiration than to root C storage under ample water supply. Interestingly, this pattern was reversed under drought. We suggest that these different response patterns reflect strategies of the managed and the abandoned grassland to enhance their respective resilience to drought, by fostering their resistance and recovery, respectively. We conclude that while severe drought can override the effects of abandonment of grassland management on the respiratory dynamics of recent C, abandonment alters strategies of belowground assimilate investment, with consequences for soil-CO2 fluxes during drought and drought-recovery.

Data were collected from a common garden experiment in the Austrian Central Alps using intact soil-vegetation monoliths from two differently managed grasslands. The first grassland is an extensively managed hay meadow, cut once per year for hay production. The second grassland has been abandoned since 1983. Monoliths were installed in the year previous to the experiment (2013). The experiment was conducted in 2014. It was constitued of an experimental pulse drought (using rain-out shelters) in June 2014. To trace the fate of recent photoassimilates in the plant-soil atmosphere system, two 13CO2 pulse-labelling experiments were conducted. The first one in the final week of the drought period, and the second one during the recovery period in July. The dataset contains processed data on soil respiration and its isotopic signature as well as data soil leachates. Furthermore, the dataset contains and R-project and R code used to analyze the dataset. The file Metadata.xlxs contains a description of data and abbreviations used in the datsets.

{"references": ["Ingrisch et al. (2020) Drought and recovery effects on belowground respiration dynamics and the partitioning of recent carbon in managed and abandoned grassland. Global Change Biology. In press."]}