Sammanfattning

Soil organic carbon (SOC) is a substantial source of atmospheric CO2, but also a large cause of uncertainties in Earth-system models. A principal control on soil CO2 release is the carbon-use efficiency (CUE) of microbial communities, which partitions the carbon (C) allocation between biosynthetic stabilization and CO2 respiration during SOC decomposition. In Earth-system models, CUE is commonly considered as a constant, although it should be susceptible to environmental factors such as temperature. We explored CUE across a set of land-uses and temperatures, and we show the hitherto neglected phenomenon that land-use can alter the temperature response of CUE. In arable soils, CUE was constant over a temperature range between 5 and 20 degrees C, but it decreased with temperature in ley farming, grassland, and forest soils at temperatures above 12.5 degrees C. The decrease in CUE was strongest for forest soils. Implementing our findings into a soil-C model revealed substantial differences in projected SOC losses: Assuming an increase of mean annual temperature of 2 or 4 degrees C, soils were projected to lose up to 6 or 15% of their current SOC, respectively, until they reach a new steady-state. These projections varied among land-uses. Our findings confront the current representation of CUE in global C models and challenges C sequestration strategies based on land-use changes, because land-uses such as e.g. forest ecosystems with current high C storage may lose substantially more C than agricultural soils due to strong declines of CUE.

Nyckelord

Carbon cycle; Carbon-use efficiency; Thermodynamic efficiency; Land-use; Temperature sensitivity; Soil carbon modelling

Publicerad i

Soil Biology and Biochemistry
2020, Volym: 140, artikelnummer: 107639
Utgivare: PERGAMON-ELSEVIER SCIENCE LTD

SLU författare

• Bölscher, Tobias

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Institutionen för kemi och bioteknologi, Sveriges lantbruksuniversitet
    

• Ågren, Göran

  • Institutionen för ekologi, Sveriges lantbruksuniversitet
    

• Herrmann, Anke

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Institutionen för kemi och bioteknologi, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Markvetenskap


Publikationens identifierare

DOI: https://doi.org/10.1016/j.soilbio.2019.107639

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/103364