Sammendrag
Soil respiration is an important ecosystem process that releases carbon dioxide into the atmosphere. While soil
respiration can be measured continuously at high temporal resolutions, gaps in the dataset are inevitable,
leading to uncertainties in carbon budget estimations. Therefore, robust methods used to fill the gaps are needed.
The process-based non-linear least squares (NLS) regression is the most widely used gap-filling method, which
utilizes the established relationship between the soil respiration and temperature. In addition to NLS, we also
implemented three other methods based on: 1) artificial neural networks (ANN), driven by temperature and
moisture measurements, 2) singular spectrum analysis (SSA), relying only on the time series itself, and 3) the
expectation-maximization (EM) approach, referencing to parallel flux measurements in the spatial vicinity. Six
soil respiration datasets (2017–2019) from two boreal forests were used for benchmarking. Artificial gaps were
randomly introduced into the datasets and then filled using the four methods. The time-series-based methods,
SSA and EM, showed higher accuracies than NLS and ANN in small gaps (
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