Monitoring greenhouse gas fluxes in an array of Dutch natural peatlands and fen meadows using mobile&#160;Eddy covariance.&#160;
Authors: Biermann Jan , Berghuis Hanne , Nouta Reinder , Bosma Niek , Vertegaal Paul , Borren Wiebe , Veraart Jeroen , Franssen Wietse , Jans Wilma , Hutjes Ronald , Kruijt Bart 
Published: March 2022

&lt;p&gt;Natural peatlands and fen meadows have the potential to sequester CO&lt;sub&gt;2&lt;/sub&gt; from the atmosphere but can also&amp;#160;&lt;br&gt;form a major source of CH&lt;sub&gt;4&lt;/sub&gt; emissions. However, their flux dynamics, showing the diurnal and annual&amp;#160;&lt;br&gt;variation of GHG exchange depend on site characteristics such as soil/peat type, water dynamics and&lt;br&gt;management practices. It is thus essential, that carbon fluxes of different locations are individually&amp;#160;&lt;br&gt;quantified in order to assess if, from a climate perspective, CO&lt;sub&gt;2&lt;/sub&gt; uptake outweighs CH&lt;sub&gt;4&lt;/sub&gt; emission for these&amp;#160;&lt;br&gt;areas.&lt;/p&gt;&lt;p&gt;We deployed five movable eddy covariance measurement stations to chart dynamics of CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; fluxes&amp;#160;&lt;br&gt;in an array of peat soil sites. The fluxes are measured directly, alternating every few weeks between the&amp;#160;&lt;br&gt;different sites. One aim of the study is to examine the feasibility of these moveable stations, as they may&amp;#160;&lt;br&gt;reduce the relatively high investment costs of EC measurements per site. We show that moveable stations&amp;#160;&lt;br&gt;are feasible from a practical point of view, as the stations can be relocated relatively easily within the time&amp;#160;&lt;br&gt;span of a few hour.&lt;/p&gt;&lt;p&gt;The resulting carbon budgets provide insight into an array of site specific GHG exchanges over typically&amp;#160;&lt;br&gt;small temporal and spatial scales. Meteorological observations are permanently performed at all selected&amp;#160;&lt;br&gt;locations as well, along with other supportive measurements such as soil/water temperature, moisture and&amp;#160;&lt;br&gt;water level.&lt;/p&gt;&lt;p&gt;Since the measurement stations alternate between locations, robust gap filling methods are needed to&amp;#160;&lt;br&gt;obtain a complete picture of the variability of the flux dynamics over the entire year for each location. The&amp;#160;&lt;br&gt;main objective of this study is to identify most suitable and robust gap filling methods. As such&lt;br&gt;measurements from the permanent meteorological stations serve to force several gap-filling methods such&amp;#160;&lt;br&gt;as interpolation based on observed ecosystem responses, the look up table approach and more established&amp;#160;&lt;br&gt;methods. We also investigate in the use of more process-based empirical models as the gaps between&amp;#160;&lt;br&gt;measurement periods are longer. Results show that the mobile eddy covariance approach does allow&lt;br&gt;identification of significant differences in GHG flux between sites as well as meaningful aggregation to&amp;#160;&lt;br&gt;annual budgets.&lt;/p&gt;&lt;p&gt;Ultimately, enabling the monitoring at more locations than with static systems may serve as a basis for&amp;#160;&lt;br&gt;policy makers and land managers to shape nature conservation or agricultural practices that achieve a net&amp;#160;&lt;br&gt;mitigation of greenhouse warming potential.&lt;/p&gt;