Nitrous oxide (N2O) and methane (CH4) fluxes from stems of different tropical tree species in Mare Longue Nature Reserve
Katerina Machacova (project leader), Thomas Agyei, Libor Borak
Department of Ecosystem Trace Gas Exchange, Global Change Research Institute CAS, Czech Republic
The project objective was to quantify nitrous oxide (N2O) and methane (CH4) exchange of common tree species in Mare Longue Nature Reserve at the La Réunion Island (Syzygium borbonicum, Doratoxylon apetalum, Antirhea borbonica, Homalium paniculatum, Mimusops balata, and Labourdonnaisia calophylloides), of adjacent soil, and of common photoautotrophic organisms associated with the tree bark (so called cryptogams; Pyrrhobryum spiniforme, Leucoloma sp., Leucophanes sp.). The aim was to determine whether and to which extent these forest ecosystem components exchange N2O and CH4 with the atmosphere, and to clarify their role in N2O and CH4 exchange of the tropical rain forest.
The measurements were performed within the permanent experimental plots of the Mare Longue Nature Reserve in October – November 2018. The exchange of N2O and CH4 was studied on six tree species (in total 24 mature trees, incl. 9 trees with stem flux profile), 24 soil positions and 3 cryptogamic species. The fluxes were measured using non-steady-state chamber systems. The concentration changes of N2O and CH4 in chamber headspace were measured using a portable FTIR analyser (DX-4015, GASMET, Finland). After extensive data processing (flux calculation), the gas exchange rates of stems and soils will be up-scaled to the ecosystem level to roughly estimate the forest ecosystem-atmosphere greenhouse gas exchange.
The performed measurement was/is a case study with the aim to get a first overview about the greenhouse gas exchange in the tropical rain forest typical for the La Reunion Island. The project has established new cooperation with the researchers from the University of Réunion Island, which will be a basis for future common experiments (investigation of temporal and spatial heterogeneity of greenhouse gas fluxes).
This research was supported by the Czech Science Foundation (17-18112Y) and is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654182. A transnational ENVRI+ access was allocated to the Estonian team to visit the forest station. Logistical support was provided by the Mare-Longue research station, funded by the POE, the Réunion National Park and the OSU-Réunion. We thank Dr. Claudine Ah-Peng for scientific and organization help, and Yoan Benoit, Pierre Stamenoff (OSUR) and Leszek Dariusz Laptaszynski for technical and organization support.