2021 journal article
Concurrent Measurements of Soil and Ecosystem Respiration in a Mature Eucalypt Woodland: Advantages, Lessons, and Questions
Journal of Geophysical Research: Biogeosciences, 126(3).
open access via hdl.handle.net (repository)
Source: ORCID
Added: July 1, 2024
Abstract Understanding seasonal and diurnal dynamics of ecosystem respiration (R eco ) in forests is challenging, because R eco can only be measured directly during night‐time by eddy‐covariance flux towers. R eco is the sum of soil respiration (R soil ) and above‐ground respiration (in theory, R AG = R eco − R soil ). R soil can be measured day and night and can provide a check of consistency on R eco , as the difference in magnitude and time dynamic between R eco and R soil should be explained by R AG . We assessed the temporal patterns and climatic drivers of R soil and R eco in a mature eucalypt woodland, using continuous measurements (only at night for R eco ) at half‐hourly resolution over 4 years (2014–2017). Our data showed large seasonal and diurnal (overnight) variation of R eco , while R soil had a low diurnal amplitude and their difference (R eco − R soil, or R AG ) had a low seasonal amplitude. This result implies at first glance that seasonal variation of R eco was mainly influenced by R soil while its diurnal variation was mainly influenced by R AG . However, our analysis suggests that the night‐time R eco decline cannot realistically be explained by a decline of R AG . Chamber measurements of autotrophic components at half‐hourly time resolution are needed to quantify how much of the R eco decline overnight is due to declines in leaf or stem respiration, and how much is due to missing storage or advection, which may create a systematic bias in R eco measurements. Our findings emphasize the need for reconciling bottom‐up (via components measured with chambers) and direct estimates of R eco (via eddy‐covariance method).