Dataset for 'A Small Nimble In situ Fine-scale Flux method for measuring tree stem greenhouse gas emissions and processes (S.N.I.F.F)' - Ecosystems
This dataset support our methods publication recently accepted in Ecosystems Manuscript highlights • Stable isotope analysis suggests δ13C-CH4 oxidation and fractionation occurs during transport • Substantial fine-scale vertical and radial heterogeneity identified in tree stem CH4 emissions • Novel smartphone 3D photogrammetry can more accurately estimate the tree stem surface area compared to traditional methods • Fine-scale sampling method shows 86-89% of methane flux emanates from the lower 30cm of wetland forest tree stems Manuscript Abstract: Tree stem methane emissions are gaining increasing attention as an overlooked atmospheric source pathway. Existing methods for measuring tree stem greenhouse gas fluxes and isotopes may provide robust integrated emission estimates, but due to their coarse resolution, the capacity to derive insights into fine-scale dynamics of tree stem emissions are limited. We demonstrate and field-test an alternative method that is Small, Nimble, In situ and allows for Fine-scale Flux (‘SNIFF’) measurements, on complex and contrasting stem surfaces. It is light weight and therefore suitable to remote field locations enabling real time data observations allowing for field-based data driven sampling regimes. This method facilitated novel results capturing fine-scale vertical and radial methane flux measurements (5cm increments) and revealed: (1) 86-89% of methane emissions emanated from the lower 30cm of sampled wetland tree species; (2) uncovered clear vertical and horizontal trends in δ13C-CH4 possibly due to fractionation associated with oxidation and mass-dependant fractionation during diffusive transport; and (3) demonstrated how substantial radial heterogeneity can occur. We also compared a variety of upscaling approaches to estimate methane flux per tree when using this method, including novel smartphone 3D photogrammetry, that resulted in a substantially higher stem surface area estimation (>16 to 36%) than traditional empirical methods. Utilising small chambers with high radial and vertical resolution capabilities may therefore facilitate future assessments into the drivers, pathways, oxidation sinks and magnitude of various tree stem greenhouse gas emissions, and compliment previous broad-scale sampling techniques.