Temperature thresholds of ecosystem respiration at a global scale

Ecosystem respiration is a major component of the global terrestrial carbon cycle and is strongly influenced by temperature. The global extent of the temperature-ecosystem respiration relationship, however, has not been fully explored. Here, we test linear and threshold models of ecosystem respiration across 210 globally distributed eddy covariance sites covering the most extensive temperature range ever studied. Results show the emergence of temperature thresholds to the global temperature-ecosystem respiration relationship, which represent transitions in the temperature dependence and sensitivity of ecosystem respiration. At longer timescales, annual ecosystem respiration rates show a markedly reduced temperature dependence and sensitivity, and the emergence of a single mid-temperature threshold for both air and soil temperature. Our study indicates a distinction in the influence of environmental factors, including temperature, on ecosystem respiration between latitudinal and climate gradients at short (half-hourly) and long (annual) timescales.