Work

Vegetation Type Dominates the Spatial Variability in CH4 Emissions Across Multiple Arctic Tundra Landscapes

Year: 2016

Type: article

Abstract: Methane (CH 4 ) emissions from Arctic tundra are an important feedback to global climate. Currently, modelling and predicting CH 4 fluxes at broader scales are limited by the challenge of upscaling plot-scale measurements in spatially heterogeneous landscapes, and by uncertainties regarding key controls of CH 4 emissions. In this study, CH 4 and CO 2 fluxes were measured together with a range of environmental variables and detailed vegetation analysis at four sites spanning 300 km latitude from Barrow to Ivotuk (Alaska). We used multiple regression modelling to identify drivers of CH 4 flux, and to examine relationships between gross primary productivity (GPP), dissolved organic carbon (DOC) and CH 4 fluxes. We found that a highly simplified vegetation classification consisting of just three vegetation types (wet sedge, tussock sedge and other) explained 54% of the variation in CH 4 fluxes across the entire transect, performing almost as well as a more complex model including water table, sedge height and soil moisture (explaining 58% of the variation in CH 4 fluxes). Substantial CH 4 emissions were recorded from tussock sedges in locations even when the water table was lower than 40 cm below the surface, demonstrating the importance of plant-mediated transport. We also found no relationship between instantaneous GPP and CH 4 fluxes, suggesting that models should be cautious in assuming a direct relationship between primary production and CH 4 emissions. Our findings demonstrate the importance of vegetation as an integrator of processes controlling CH 4 emissions in Arctic ecosystems, and provide a simplified framework for upscaling plot scale CH 4 flux measurements from Arctic ecosystems.

Source: Ecosystems

DOI: 10.1007/s10021-016-9991-0