16 Nov 2020

16 Nov 2020

Review status: a revised version of this preprint was accepted for the journal BG.

The role of termite CH4 emissions on ecosystem scale: a case study in the Amazon rain forest

Hella van Asperen1, João Rafael Alves-Oliveira2, Thorsten Warneke1, Bruce Forsberg3,a, Alessandro Carioca de Araujo4,5, and Justus Notholt1 Hella van Asperen et al.
  • 1Institute of Environmental Physics (IUP), University of Bremen, Otto-Hahn-Allee 1, Bremen, 28359, Germany
  • 2Coordenação de Pesquisas em Entomologia (CPEN), Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Aleixo, AM 69060-001, Manaus, Brazil
  • 3Coordenação de Dinâmica Ambiental (CODAM), Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Petrópolis, AM 69067-375, Manaus, Brazil
  • 4Programa de Grande Escala da Biosfera-Atmosfera na Amazônia (LBA), Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, 2936, Aleixo, AM 69060-001, Manaus, Brazil
  • 5Brazilian Agricultural Research Corporation (EMBRAPA), Embrapa Amazônia Oriental, Tv. Dr. Enéas Piheiro, s/n, Marco, PA 66095-903, Caixa postal 48, Belém, Brazil
  • acurrently at: Vermont Agency of Natural Resources, Department of Environmental Conservation, Vermont-USA

Abstract. The magnitude of termite methane (CH4) emissions is still an uncertain part of the global CH4 budget and current emission estimates are based on limited field studies. We present in-situ CH4 emission measurements of termite mounds and termite mound sub samples, performed in the Amazon rain forest. Emissions of five termite mounds of the species Neocapritermes brasiliensis were measured by use of a large flux chamber connected to a portable gas analyser, measuring CH4 and CO2. In addition, the emission of mound sub samples was measured, after which termites were counted, so that a termite CH4 and CO2 emission factor could be determined.

Mound emissions were found to range between 17.0–34.8 nmol mound−1 s−1 for CH4 and between 1.6–13.5 μmol mound−1 s−1 for CO2. A termite emission factor of 0.32 μmol CH4 gtermite−1 h−1 was found, which is twice as high as the only other reported average value for the Amazon. By combining mound emission measurements with the termite emission factor, colony sizes could be estimated, which were found to range between 50–120 thousand individuals. Estimates were similar to literature values, and we therefore propose that this method can be used as a quick non-intrusive method to estimate termite colony size in the field.

The role of termites in the ecosystems CH4 budget was evaluated by use of two approaches. Termite mound emission values were combined with local termite mound density numbers, leading to an estimate of 0.15–0.71 nmol CH4 m−2 s−1 on average emitted by termite mounds. In addition, the termite CH4 emission factor from this study was combined with termite density numbers, resulting in an estimate of termite emitted CH4 of ~1.0 nmol m−2 s−1. Considering the relatively low net CH4 emissions previously measured at this ecosystem, we expect that termites play an important role in the CH4 budget of this Terra Firme ecosystem.

Hella van Asperen et al.

Status: final response (author comments only)
Status: final response (author comments only)
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Hella van Asperen et al.

Hella van Asperen et al.


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Short summary
Termites are insects which are highly abundant in tropical ecosystems. It is known that termites emit CH4, an important greenhouse, but their absolute emission remains uncertain. In the Amazon rain forest, we measured CH4 emissions from termite nests and groups of termites. In addition, we tested a fast and non-destructive field method to estimate termite nest colony size. We found that termites play a significant role in the ecosystems CH4 budget, and probably emit more than currently assumed.