View from above looking straight down at the top of the large ATTO tower, which stands out as an orange square above the green tree tops far below. Diagonally, the guy wires run from the tower into the forest.

Measurement of greenhouse gas concentrations and fluxes

Greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) are important players in different biogeochemical cycles. Continuous concentration measurements of CH₄ and N₂O are still rare, especially in tropical rainforests. At the foot of the 325m Tall Tower, an FTIR-spectrometer (Spectronus) will be installed, which will measure the tower concentrations of CO₂, CH₄, N₂O, CO & ¹³C-CO₂ with high precision and frequency. Concentration measurements at these high heights are of interest, because they can give information about large scale ecosystem processes and long scale transport patterns, connecting to the project of Santiago Botía and Christoph Gerbig.

The shady forest floor is covered with leaves. Around it, alternating tree trunks and palm leaves rise up. In the center, a woman kneels on the ground, in front of here a blue tarp on which several measuring devices are set up. — The measurement of CH₄ and CO₂ emissions from termite nests, by use of a large flux chamber and a portable Los Gatos gas analyzer.

© S.M. Bulthuis

The measurement of CH₄ and CO₂ emissions from termite nests, by use of a large flux chamber and a portable Los Gatos gas analyzer.

© S.M. Bulthuis

In addition, different Picarro instruments will be installed at the 80m tower, which will measure concentrations of H₂O, CO₂, CH₄& CO, and the isotopic composition of CO₂, CH₄ and H₂O. Since this tower represents an undisturbed forest area, these measurements can be used to study the below-canopy behaviors of the different gases, connecting to the projects of Sam Jones and Shuiro Komiya.

In addition to these large scale measurements, we aim to understand the different local ecosystem processes wherein these greenhouse gases play a role. For example, to what extend is the forest soil a sink for CH₄, and how is it related to soil VOC-emissions? And what is the role of termite emission in the total ecosystem CH₄ budget, and how can these fluxes be estimated? Another focus will be on the fluxes of carbon monoxide (CO), a gas which is considered an indirect greenhouse gas. In the past, tropical soils have been hypothesized to be a source as well as a sink of CO. By combining continuous tower measurements with local field experiments, we hope to further understand the carbon monoxide fluxes in this ecosystem.