Six years of ecosystem-atmosphere greenhouse gas fluxes measured in a sub-boreal forest

Andrew D Richardson,Holly Hughes,David Y Hollinger,Julie K Shoemaker,Eric A Davidson,Kathleen Savage

doi:10.1038/s41597-019-0119-1

Abstract

Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the greenhouse gases largely responsible for anthropogenic climate change. Natural plant and microbial metabolic processes play a major role in the global atmospheric budget of each. We have been studying ecosystem-atmosphere trace gas exchange at a sub-boreal forest in the northeastern United States for over two decades. Historically our emphasis was on turbulent fluxes of CO2 and water vapor. In 2012 we embarked on an expanded campaign to also measure CH4 and N2O. Here we present continuous tower-based measurements of the ecosystem-atmosphere exchange of CO2 and CH4, recorded over the period 2012–2018 and reported at a 30-minute time step. Additionally, we describe a five-year (2012–2016) dataset of chamber-based measurements of soil fluxes of CO2, CH4, and N2O (2013–2016 only), conducted each year from May to November. These data can be used for process studies, for biogeochemical and land surface model validation and benchmarking, and for regional-to-global upscaling and budgeting analyses.

Highlights

Background & SummaryIncreases in atmospheric concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are driving the radiative forcing of climate that has occurred since 18001
Soil processes are the dominant source of N2O, with fluxes from natural systems accounting for about 35% of global emissions[7]
Agricultural practices, fossil fuel combustion, and industrial activities further contribute to N2O emissions[7]

Summary

Introduction

Increases in atmospheric concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are driving the radiative forcing of climate that has occurred since 18001. While these increases are predominantly the result of human activities, significant exchanges of these gases occur naturally between terrestrial ecosystems and the atmosphere. Global photosynthetic uptake by terrestrial ecosystems (≈123 ± 8 Pg C y-1 as CO2, ref.2) is a massive flux, but at annual time scales under current climate conditions this uptake is largely offset by a comparable efflux of respiratory carbon back to the atmosphere. Soil processes are the dominant source of N2O, with fluxes from natural systems accounting for about 35% of global emissions[7]. For each of CO2, CH4, and N2O, natural biological processes play an important role in the global budget

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