Closed chamber method
• Pros:
• Provides direct measurements of gas fluxes from soil surface (total soil
respiration – autotrophic + heterotrophic)
• Sufficient replication allows up-scaling to give site emissions
• Rigorous application of specific methodologies can allow measurement of
(just) heterotrophic soil emissions
• Cons:
• Care with experimental set-up is essential, e.g.
• site heterogeneity
• timing of sample collection - must take account of diurnal & seasonal
differences
• risk of measurement bias if total soil respiration is measured (e.g. distance
from rooted trees could influence autotrophic : heterotrophic respiration
ratio)
• Risk of disturbance from measures used to exclude autotrophic emissions
when attempting to measure only heterotrophic emissions (e.g. root removal)
• Does not capture fluvial losses of carbon (POC + DOC)
• Biggest challenge is modelling annual fluxes from point measurements