Are methane emissions from mangrove stems a cryptic carbon loss pathway? Insights from a catastrophic forest mortality.
Description
Here we provide the raw data from our publication in New Phytologist (accepted 10 June 2019). Out study highlights are as follows: • Growing evidence indicates tree-stem methane emissions may be an important and un-accounted for component of local, regional and global carbon budgets. Studies to date have focussed on upland and freshwater swamp-forests; however, no data on tree-stem fluxes from estuarine species currently exist. • Here we provide the first-ever mangrove tree-stem methane flux measurements from >50 trees (n=230 measurements), in both standing dead and living forest, from a region suffering a recent large-scale climate-driven dieback event (Gulf of Carpentaria, Australia). • Average methane emissions from standing dead mangrove tree-stems were 249.2 ± 41.0 µmol m-2 d-1 and eight-fold higher than from living mangrove tree-stems (37.5 ± 5.8 µmol m-2 d-1). The average methane flux from tree-stem bases (~10cm above ground) was 1071.1 ± 210.4 µmol m-2 d-1 and 96.8 ± 27.7 µmol m-2 d-1 from dead and living stands respectively. Sediment methane fluxes and redox potentials did not differ significantly between living and dead stands. Our results suggest both dead and living tree-stems act as methane conduits to the atmosphere, bypassing potential sedimentary oxidation processes. • Although large uncertainties exist when up-scaling data from small-scale temporal measurements, we estimated that dead mangrove tree-stem emissions may account for ~26 % of the net ecosystem methane flux.