DOI: 10.5061/dryad.hmgqnk9f6
title: Resistance-recovery tradeoff of soil microbial communities under altered rain regimes: An experimental test across European agroecosystems

description: With the increased occurrence of climate extremes, there is an urgent need
 to better understand how management strategies affect the capacity of the
 soil microbial community to maintain its ecosystem functions (e.g.
 nutrient cycling). To address this issue, intact monoliths were extracted
 from conventional and ecological managed grasslands in three countries
 across Europe and exposed under common air condition (temperature and
 moisture) to one of three altered rain regimes (dry, wet and intermittent
 wet/dry) as compared to a normal regime. Subsequently, we compared the
 resistance and recovery of the soil microbial biomass, potential enzyme
 activities and community composition. The microbial community composition
 differed with soil management and rain regimes. Soil microbial biomass
 increased from the wetter to the dryer rain regime, paralleling an
 increase of available carbon and nutrients, suggesting low sensitivity to
 soil moisture reduction but nutritional limitations of soil microbes.
 Conversely, enzyme activities decreased with all altered rain regimes.
 Resistance and recovery (considering absolute distance between normal and
 altered rain regime) of the microbial communities depended on soil
 management. Conventional-intensive management showed higher resistance of
 two fundamental properties for nutrient cycling (i.e. bacterial biomass
 and extracellular enzyme activities) yet associated with more important
 changes in microbial community composition. This suggests an internal
 community reorganization promoting biomass and activity resistance.
 Conversely, under ecological management bacterial biomass and enzyme
 activities showed better recovery capacity, whereas no or very low
 recovery of these properties was observed under conventional management.
 These management effects were consistent across the three altered rain
 regimes investigated, indicating common factors controlling microbial
 communities’ response to different climate-related stresses. Synthesis and
 applications: Our study provides experimental evidence for an important
 trade-off for agro-ecosystem management between i.) stabilizing nutrient
 cycling potential during an altered rain regime period at the expense of
 very low recovery capacity and potential long term effect (conventional
 sites) and ii.) promoting the capacity of the microbial community to
 recover its functional potential after the end of the stress (ecological
 sites). Thus management based on ecologically sound principles may be the
 best option to sustain long-term soil functioning under climate change.
description: The experiment was setup using intact soil monoliths extracted at
 three sites across Europe on October 2015. At each site, soil monoliths
 were extracted in fields under ecological and conventional management.
 Ecological managed plots never used synthetic fertilizers and met organic
 farming requirements. All sites were cultivated for forage at the sampling
 time: permanent and sown mountain grasslands in France (Vercors),
 clover-grass in an arable cropping system in Switzerland (Therwil), and
 permanent and sown grasslands in an agroforestry system in Portugal
 (Montemor-o-Novo). In total 120 soil monoliths were extracted.
 After sampling, monoliths were transported in a climate chamber.
 During the first 81 days, 50%-60% of the maximum water holding capacity
 (WHC<sub>max</sub>) was maintained followed by a first
 sampling (T0) of the upper 10 cm of soil for one monolith per
 plot. After this acclimation period, 4 rain regimes
 were simulated during 263 days with the following condition: Normal rain
 regime : 50%-60% of the WHCmax, ‘Dry’ rain regime : 20%-30%, ‘Wet’ rain
 regime : 70%-80%  and ‘Intermittent’ rain regime : a cycle of wet (74
 days), dry (125 days) and normal (64 days) rain regime. This period was
 followed by a sampling (T1) of 98 cm<sup>3</sup> soil core (5
 cm diameter and 5 cm height). Finaly, all monoliths
 were then set again to Normal rain regime for 89 days followed by a last
 destructive sampling (T2) of the upper 10cm of soil as for T0.
  
description: See readme of the data file.