Dataset for: Heat wave-induced microbial thermal trait adaptation and its reversal in the Subarctic
Cite this dataset
Tájmel, Dániel (2023). Dataset for: Heat wave-induced microbial thermal trait adaptation and its reversal in the Subarctic [Dataset]. Dryad. https://doi.org/10.5061/dryad.b5mkkwhkf
Abstract
Climate change predictions suggest that arctic and subarctic ecosystems will be particularly affected by rising temperatures and extreme weather events, including severe heat waves. Temperature is one of the most important environmental factors controlling and regulating microbial decomposition in soils; therefore, it is critical to understand its impact on soil microorganisms and their feedback to climate warming. We conducted a warming experiment in a subarctic birch forest in North Sweden to test the effects of summer heat waves on the thermal trait distributions that define the temperature dependencies for microbial growth and respiration. We also determined the microbial temperature dependences 10 and 12 months after the heat wave simulation had ended to investigate the persistence of the thermal trait shifts. As a result of warming, the bacterial growth temperature dependence shifted to become warm-adapted, with a similar trend for fungal growth. For respiration, there was no shift in the temperature dependence. The shifts in thermal traits were not accompanied by changes in α- or β-diversity of the microbial community. Warming increased the fungal-to-bacterial growth ratio by 33% and decreased the microbial carbon use efficiency (CUE) by 35%, and both these effects were caused by the reduction in moisture the warming treatments caused, while there was no evidence that substrate depletion had altered microbial processes. The warm-shifted bacterial thermal traits were partially restored within one winter but only fully recovered to match ambient conditions after one year. To conclude, summer heat waves in the Subarctic resulted in (i) shifts in microbial thermal trait distributions; (ii) lower microbial process rates caused by decreased moisture, not substrate depletion; and (iii) no detectable link between the microbial thermal trait shifts and community composition changes.
README: Dataset for Heat wave-induced microbial thermal trait adaptation and its reversal in the Subarctic
https://doi.org/10.5061/dryad.b5mkkwhkf
We conducted a field warming experiment to test the effects of summer heat waves on microbial temperature traits. The field warming experiment included 4 independent blocks, and each block included 2 control and warmed plots. The dataset includes the field and soil characteristics (August 2020), in situ temperature and moisture measurements (between June 2020 and August 2020), as well as bacterial growth, fungal growth, and respiration rates in C unit (μg C g-1 SOM h-1) measured at different time points (August 2020, June 2021, August 2021).
The warming treatments started in mid-June and ran until mid-August, covering the growing season of 2020. In mid-August 2020, the IR heaters were removed after two months of warming, and the plots were left without warming treatment under ambient conditions. Then, after one winter (in June 2021) and one entire annual cycle (in August 2021), the plots were sampled again to investigate if any warming legacy remained in the microbial community temperature relationships.
Files included contain all data from the article (DOI), organised as follows:
1. This file includes the soil and field characteristics: water content (WC) (g H2O g-1 dwt), soil organic matter (g SOM g-1 dwt), soil pH, soil electrical conductivity (µS cm-1), water holding capacity (g H2O g-1 dwt), total carbon (g C g-1 dwt), total nitrogen (g N g-1 dwt), NDVI (normalized difference vegetation index), fPAR (the fraction of photosynthetically active radiation), LAI (the projected area of leaves over the unit of measured ground area).
2. Soil temperature (°C) (-8 cm) measured with 15 min resolution
3. Soil volumetric moisture (cm3 cm-3) (0 and -14 cm) with 15 min resolution
4. Surface temperature (°C) (0 cm) measured with 15 min resolution
5. Air temperature (°C) (+15 cm) measured with 15 min resolution
6. Microbial rates (bacterial growth\, fungal growth\, and respiration data) (µg C g-1 SOM h-1) measured in August 2020
7. Microbial rates (bacterial growth\, fungal growth\, and respiration data) (µg C g-1 SOM h-1) measured in June 2021
8. Microbial rates (bacterial growth\, fungal growth\, and respiration data) (µg C g-1 SOM h-1) measured in August 2021
9. Microbial rates (bacterial growth\, fungal growth\, and respiration data) (µg C g-1 SOM h-1) measured at 20°C at field moisture and 50% WHC
10. Carbon use efficiency and fungal-to-bacterial growth ratio measured in August 2020
Description of the data and file structure
The 4 independent blocks are called BLOCK1, BLOCK2, BLOCK3, BLOCK4. Each block includes 2 control and 2 warmed plots. For BLOCK1: CONTROL1, WARMING1, CONTROL2, WARMING2. For BLOCK2: CONTROL3, WARMING3, CONTROL4, WARMING4. For BLOCK3: CONTROL5, WARMING5, CONTROL6, WARMING6. For BLOCK4: CONTROL7, WARMING7, CONTROL8, WARMING8.
Prior to the statistical analysis, we combined field technical replicates into means per block, ending with one control and one warming treatment per block.
In files including 2-10, in all columns, “NA” (Not Available) values are used to signify instances where the data could not be obtained or recorded. To see how the data was used and analyzed, see Materials & Methods and Results section of the connected article, DOI: 10.1111/GCB.17032.
Sharing/Access information
The sequencing data that support the findings are available on European Nucleotide Archive with the primary accession number PRJEB54006 (http://www.ebi.ac.uk/ena/data/view/PRJEB54006).
Methods
In brief, soil and field characteristics: We measured gravimetric soil moisture (105°C for 24 h) and SOM content through loss on ignition (550°C for 12 h). Soil pH and electrical conductivity (EC) were determined in a 1:5 (w:v) soil:water extraction. Soil total carbon (TC) and total nitrogen (TN) were measured using Dumas dry combustion by a C/N 144 elemental analyzer (VarioMAX CN, Elementar, Germany). The normalized difference vegetation index (NDVI) as a proxy for plant productivity, the fraction of photosynthetically active radiation (fPAR), and the leaf area index (LAI; the projected area of leaves over the unit of measured ground area; m2 m-2) were determined with NDVI meter (SpectroSense2+, Skye, UK).
The temperature and moisture data were collected by using data loggers (TMS-4 29cm, TOMST®, Czech Republic) with 15 min resolution. The in situ soil (-8 cm), surface (0 cm), air (+15 cm) temperatures, and volumetric soil moisture (between 0 and -14 cm) were monitored.
Bacterial growth, fungal growth, and respiration were determined at ten different screening temperatures from 0 to 45°C in 5°C intervals. Bacterial growth was determined by radioactively labeled 3H-Leucine (Leu) incorporation into extracted bacteria from 0.5 g of fresh soils. Fungal growth was measured in 0.5 g of fresh soils using 14C-acetate (Ace)-in-ergosterol incorporation method. Microbial respiration was measured by a gas chromatograph equipped with a methanizer and flame ionization detector.
Funding
Danmarks Frie Forskningsfond, Award: 9036-00004B
Knut and Alice Wallenberg Foundation, Award: KAW 2022.0175
Swedish Research Council, Award: 2020-04083
Swedish Research Council, Award: 2021-00164