A novel automatic chamber system for high to medium spatial and temporal resolution for the determination of CO2 (NEE & RECO), CH4 and N2O fluxes in ecosystems.
Authors: Eickenscheidt Tim , Bockermann Carla , Eroglu Fehmi , Heerdt Christian , Linß Andreas , Reiche Marco , Reth Sascha , Schröder Tobias , Drösler Matthias 
Published: March 2022

&lt;p&gt;In the face of climate warming the accurate determination of greenhouse gas (GHG) fluxes from ecosystems is of crucial importance for the assessment and development of successful mitigation measures. Several different GHG measurement systems are already on the market. Micro metrological approaches (e.g. eddy covariance) operate with high frequency measurements to achieve a high temporal resolution without influencing the ecosystem. Manual chambers are well suited for capturing spatial heterogeneity or for conducting small-scale experiments. To overcome the low temporal resolution when using manual chambers, several commercial or self-made automatic chamber systems exist. As far as we know, up to date there are only two robotic chamber systems that are suitable for virtually undisturbed measurements of GHG on ecosystem scale: one at the Leibniz Center for Agricultural Landscape Research (ZALF) and one at the Karlsruhe Institute of Technology (IMK-IFU). However, to meet the challenge for accurate measurements in ecosystems with tall growing vegetation (up to 2 m height), we developed a new modular robotic chamber system. Opaque and transparent chambers on rails allow for alternating measurements of net ecosystem CO&lt;sub&gt;2&lt;/sub&gt; exchange (NEE), ecosystem respiration (RECO), CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O measurements on up to 36 experimental plots (each 1 m&amp;#178;) distributed over an area of 16 x 30 m. The system is equipped with four infrared gas analyzers (LI-840, LICOR Biosciences, USA) for the detection of CO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O concentrations and one cavity ring-down spectroscopy (CRDS) instrument to measure N&lt;sub&gt;2&lt;/sub&gt;O, CH&lt;sub&gt;4&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O concentrations (G2308, Picarro, USA). We installed the system in a small-scale paludiculture experiment with three different water levels and four different plant species. Depending on the time of year and magnitude of the flux rate, a maximum of 920 CO&lt;sub&gt;2&lt;/sub&gt; or 108 CH&lt;sub&gt;4&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt;O measurements are achievable per measuring day at our test site. Ancillary measurements of chamber temperature and photosynthetic active radiation (PAR) as well as outside air pressure, PAR and wind speed are additionally recorded in 1-second intervals. All data are transferred to a database on a network server via a cellular communication system. We will give insights into the new automatic chamber system, discuss advantages and challenges. We will further share our experiences from a two-year measurement period and give an overview of some first results from GHG fluxes. The development of the system was funded within the MOORuse-project by the European Union (European Regional Development Fund) and the Bavarian State Ministry of the Environment and Consumer Protection [funding code: 64b-U8639.1-2015/8-14].&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;