Towards a realistic representation of stem respiration in global models

Stem respiration accounts for a large fraction of total ecosystem
respiration and plays a significant role in global carbon budgets.
Nevertheless, knowledge on its underlying physiology remains
largely unexplored and consequently its estimation in terrestrial
biosphere models (TBMs) is poorly developed. The main goal of this
project is to improve representation of stem respiration in TBMs. To
this end, a standard methodology to sample stem respiratory fluxes
(CO2 efflux and O2 influx) will be proposed to quantify stem
respiration by means of state-of-the-art approaches. This standard
methodology will be applied by an international scientific network
currently working in stem hydraulic modelling, and the obtained
datasets will be implemented in a mechanistic model of stem
respiration at the organ level (REStemPIRE). In this way, key
parameters widely applied in TBMs (YG, Q10, Rbase; growth yield,
temperature sensitivity, and basal respiration rates) will be calibrated
across wide gradients of environmental conditions. The resulting
global database of stem respiratory traits will be analyzed within the
context of leading TBMs to evaluate their sensitivity to a more
realistic (organ-based) parameterization. Model refinements
according to processes described in REStemPIRE will be additionally
tested to advance towards a more realistic representation of woody
tissue respiration in TBMs and improve accuracy of current estimates
of whole-plant respiration at a global scale.