Reconciling Top‐Down and Bottom‐Up Estimates of Ecosystem Respiration in a Mature Eucalypt Forest
Year: 2024
Type: article
Abstract: Ecosystem respiration (R eco ) arises from interacting autotrophic and heterotrophic processes constrained by distinct drivers. Here, we evaluated up‐scaling of observed components of R eco in a mature eucalypt forest in southeast Australia and assessed whether a land surface model adequately represented all the fluxes and their seasonal temperature responses. We measured respiration from soil (R soil ), heterotrophic soil microbes (R h ), roots (R root ), and stems (R stem ) in 2018–2019. R eco and its components were simulated using the CABLE–POP (Community Atmosphere‐Biosphere Land Exchange–Population Orders Physiology) land surface model, constrained by eddy covariance and chamber measurements and enabled with a newly implemented Dual Arrhenius and Michaelis‐Menten (DAMM) module for soil organic matter decomposition. Eddy‐covariance based R eco (R eco.eddy , 1,439 g C m −2 y −1 ) was slightly higher than the sum of the respiration components (R eco.sum, 1,295 g C m −2 y −1 ) and simulated R eco (1,297 g C m −2 y −1 ). The largest mean contribution to R eco was from R soil (64%) across seasons. The measured contributions of R h (49%), R root (15%), and R stem (22%) to R eco.sum were very close to model outputs of 46%, 11%, and 22%, respectively. The modeled R h was highly correlated with measured R h (R 2 = 0.66, RMSE = 0.61), empirically validating the DAMM module. The apparent temperature sensitivities (Q 10 ) of R eco were 2.22 for R eco.sum , 2.15 for R eco.eddy , and 1.57 for CABLE‐POP. This research demonstrated that bottom‐up respiration component measurements can be successfully scaled to eddy covariance‐based R eco and help to better constrain the magnitude of individual respiration components as well as their temperature sensitivities in land surface models.
DOI: 10.1029/2024jg008064
Institutions: Kangwon National University, California Institute of Technology, Argonne National Laboratory, Western Sydney University, Commonwealth Scientific and Industrial Research Organisation, CSIRO Environment, Fudan University, University of Technology Sydney, North Carolina State University, The University of Melbourne, University of Maryland Center for Environmental Science
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDGs: Life on land, Climate action
Open Access status: hybrid
Estimated APC paid: $3,880
OpenAlex ID: W4403372046