The temperature sensitivity of soil: microbial biodiversity, growth, and carbon mineralization

Abstract

Microorganisms drive soil carbon mineralization and changes in their activity with increased temperature could feedback to climate change. Variation in microbial biodiversity and the temperature sensitivities (Q₁₀) of individual taxa may explain differences in the Q₁₀ of soil respiration, a possibility not previously examined due to methodological limitations. Here, we show phylogenetic and taxonomic variation in the Q₁₀ of growth (5-35 °C) among soil bacteria from four sites, one from each of Arctic, boreal, temperate, and tropical biomes. Differences in the temperature sensitivities of taxa and the taxonomic composition of communities determined community-assembled bacterial growth Q₁₀, which was strongly predictive of soil respiration Q₁₀ within and across biomes. Our results suggest community-assembled traits of microbial taxa may enable enhanced prediction of carbon cycling feedbacks to climate change in ecosystems across the globe.

Fig. 1. Soil respiration, microbial growth, and their temperature sensitivity.

Cumulative soil respiration (A) and microbial growth rate (C) for soils from four biomes over a 5-day incubation at four temperatures (5–35 °C). Soil respiration temperature sensitivity (Q₁₀, B) and microbial growth rate temperature sensitivity (Q₁₀, D) were calculated for each soil between incubation temperatures (mean ± standard error). Statistical analysis of the differences for each variable among temperatures can be found in Supplementary Tables 2 and 3.

Fig. 2. Microbial biomass and respiration.

Relationship between new microbial biomass production (μg C g⁻¹ soil, Ln transformed) and soil respiration (μg C g⁻¹ soil, Ln transformed) over a 5-day incubation for four temperatures (5–35 °C) and four biomes ranging from Arctic to tropical.

Fig. 3. Temperature sensitivity of respiration and growth.

Relationship between the community-weighted temperature sensitivity (Q₁₀) of microbial growth and temperature sensitivity soil respiration for three temperature ranges and four biomes ranging from Arctic to tropical.

Fig. 4. Temperature sensitivity of microbial growth in relation to bacterial phylogeny.

A Each phylotype was categorized based on its maximum Q₁₀ among 5–15, 15–25, and 25–35 °C as “cold,” “moderate,” or “warm” responders. The pie charts represent proportion of growth Q₁₀ values in each response category at class level (with exception for Chloroflexi phyla) using data from all four sites. B Total proportion of growth Q₁₀ response for each biome and across all biomes. Phylogenetic statistical analysis for growth Q₁₀ was provided in Supplementary Table 4.