Measuring Soil CO2 Efflux from Ant Nests in the Brazilian Rainforest
A common assertion is that tropical forests (especially tropical wet forests) are more productive than temperate forests, and on an annual basis, rates of net primary productivity (NPP: carbon fixed per unit area per year) of tropical wet forests greatly exceed rates of NPP in temperate deciduous or coniferous forests. Yet, on shorter time scales (daily or monthly), NPP of temperate forests is about equal to that of NPP of tropical forests, and “ecologically relevant” productivity is thought to be highest in latitudes between 30° and 50° . Comparable data for organisms at other trophic levels, however, are scant; for example, the carbon flux rate from soils (i.e., “soil respiration”) is a crucial part of any terrestrial ecosystem model, but values for soil respiration used in ecosystem models include only soil microbes and plant roots. Although soil respiration of ant nests rarely has been measured in the field , nests of red wood ants (Formica rufa group) in northern Europe have respiration rates nearly five times higher than that of surrounding ant-free soils . How this compares to tropical ants is unknown, but extrapolation from temperate studies suggests that contribution of ants to carbon cycling in tropical ecosystems could be quite large.
With support from the Museo Paraense Emílio Goelde in Belém, Brazil, Drs. Aaron M. Ellison (Harvard University, Harvard Forest) and Rogério R. Silva did a pilot study of CO2 efflux from ant nests at the Caxiuanã National Forest, Pará, Brazil. Instantaneous rates of soil carbon efflux from nests of five species of ground-nesting and arboreal-nesting ants and nearby soils lacking ants were measured for CO2 with an EGM-5 Portable CO2 Gas Analyzer and an SRC-2 Soil Respiration Chamber.
CO2 efflux rates from ant-free soils (mean = 1.3 µmol CO2 m-2 s-1) and from nests of the ground-nesting Mycoperus and Pheidole spp. were lower than those measured previously during the dry season at Caxiuanã (≈3 µmol CO2 m-2 s-1) , but efflux rates of both leaf-cutter ants (Atta sp.) and fire ants (Solenopsis sp.) were substantially higher than background (ant-free) levels. CO2 efflux from nests of the arboreal nesting Odontomachus species also were comparable to ant-free soils. Future work will include more extensive measurements of these and other ant species, adjacent ant-free soils, and large arboreal nests of Azteca species. Together, these data will help to improve estimates of soil CO2 fluxes from tropical forests.
 Huston, M. A., and S. Wolverton. 2009. The global distribution of net primary production: resolving the paradox. Ecological Monographs 79: 343-377.
 Peakin, G. J., and G. Josens. 1978. Respiration and energy flow. Pages 111-163 in M. V. Brian, editor. Production Ecology of Ants and Termites. Cambridge University Press.
 Jílková, V., T. Cajthaml, and J. Frouz. 2015. Respiration in wood ant (Formica aquilonia) nests as affected by altitudinal and seasonal changes in temperature. Soil Biology and Biochemistry 86: 50-57.
 Sotta, E. D., E. Veldkamp, B. R. Guimarães, R. K. Paixão, M. L. P. Ruivo, and S. S. Almeida. 2006. Landscape and climatic controls on spatial and temporal variation in soil CO2 efflux in an Eastern Amazonian rainforest, Caxiuanã, Brazil. Forest Ecology and Management 237: 57-64.
PP Systems would like to thank and acknowledge Aaron M. Ellison, (Harvard University, Harvard Forest, Petersham MA, USA) for providing the information contained in this application note.
If you would like to learn more about this exciting research, please contact PP Systems.
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Figure. Estimates of CO2 efflux from ant nests at Caxiuanã and ant-free soils (“0 Control”). Box plots illustrate medians, quartiles, and upper and lower deciles; widths of the boxes are proportional to sample size, and points denote values of individual observations taken in the morning (red), mid-day (green), and afternoon (blue).
EGM-5 Portable CO2 Gas Analyzer and SRC-2 Soil Respiration Chamber on a Solenopsis nest at the Caxiuanã field station.
Custom collar on a Mycocepurus nest in the lab compound at the Caxiuanã field station.
Aaron Ellison (left) and Rogério Silva (right) measuring CO2 efflux from a Solenopsis nest at Caxiuanã.
Studying Volcanic Activity Using Drones and Sensors to Accurately and Precisely Predict Volcanic Explosive Eruptions
A team of research scientists from McGill University (Montreal, Quebec CANADA), Universidad de Costa Rica (San Jose, Costa Rica), and the Observatorio Vulcanológico y Sismológico de Costa Rica (Heredia, Costa Rica) are currently developing a series of drones and associated instrumentation to study Turrialba volcano in Costa Rica. This volcano has shown increasing activity during the last 20 years, and the volcano is currently in a state of heightened unrest as exemplified by recent explosive activity in May-August 2016. The eruptive activity has made the summit area inaccessible to normal gas monitoring activities, prompting development of new techniques to measure gas compositions. The team has been using two drones, a DJI Spreading Wings S1000 octocopter and a Turbo Ace Matrix-i quadcopter, to airlift a series of instruments to measure volcanic gases in the plume of the volcano.
These instruments comprise optical and electrochemical sensors to measure CO2 (SBA-5 CO2 Gas Analyzer – PP Systems), SO2, and H2S concentrations which are considered the most significant species to help forecast explosive eruptions and determine the relative proportions of magmatic and hydrothermal components in the volcanic gas. The integrated payloads weigh 1-2 kg, which can typically be flown by the drones in 10-20 minutes at altitudes of 2000-4000 meters. Our broader goals are to map gases in detail with the drones in order to make flux measurements.
MINIGAS – Developed at the Universidad de Costa Rica, this compact instrument measures CO2, SO2, and H2S , as well as GPS location, pressure, temperature, and humidity. Data are stored on data loggers and can also be transmitted by telemetry. Total weight is 1.2 kg.
MICROGAS – Developed at McGill University, this instrument measures CO2, H2O, SO2, and H2S. The CO2-H2O infrared sensor is made by PP Systems, while the SO2 and H2S electrochemical sensors are made by City Technology. Data are recorded on Grant Yoyo dataloggers. The entire package including battery weighs 1.14 kilograms.
We now have the means to forecast explosive eruptions. The key information that is gathered includes gas, seismic, and geodetic data which indicate (a) overpressure and (b) open system behavior. See Examples 1 through 4.
Example 1: From: De Moor et al. 2016, J. Geophys. Res. 121, 5761-5775
Example 2: From: Narváez M. et al. 1997, J. Volcanol. Geotherm. Res. 77, 159-171; Gómez M. and Torres C., 1997, J. Volcanol. Geotherm. Res. 77, 173-193
Example 3: From: Martinelli 1990, J. Volcanol. Geotherm. Res. 41, 297-314
Example 4: From: Druitt et al. 2002, Geol. Soc. London Mem. 21, 281-306
PP Systems would like to thank and acknowledge (left to right) Ernesto Corrales (GAS Lab, CICANM-Univ. de Costa Rica), Fiona D. D’Arcy (McGill University, Montreal, QC Canada), Maarten J. de Moor (Observatorio Vulcanológico y Sismológico de Costa Rica, Heredia, Costa Rica), Dr. John Stix (McGill University, Montreal, QC Canada), Alfredo Alan (GAS Lab, CICANM-Univ. de Costa Rica), and Dr. Jorge Andres Diaz (GAS Lab, CICANM-Univ. de Costa Rica) (not shown) and for providing the information contained in this application note.
SBA-5 CO2 Gas Analyzer including H2O sensor, pump and enclosure.
Example 1. Turrialba 2014-2015 (Costa Rica):
CO2/sulfur ratio increases substantially prior to explosive eruptions and ash emissions
Example 2. Galeras 1993 (Colombia):
Monochromatic seismic signals (“tornillos”) systematically increase in number and duration, and decrease in dominant frequency, prior to explosive eruptions.
Example 3. Nevado del Ruiz 1985 (Colombia):
Banded tremor on 7 September, 4 days prior to ash emission on 11 September. Each tremor cycle is 15-20 minutes’ duration.
Example 4. Soufrière Hills volcano, 1997 (Montserrat):
Inflation cycles shown in (a), RSAM in (b). Peaks in tilt and RSAM correspond to vulcanian eruptions. Note the ~12-hour cyclicity from 4 to 9 July.
Optical Sampling in Antarctica with the UniSpec-DC
Researchers from a terrestrial ecology group (Systems Ecology Group, Univ. of Texas-El Paso), part of the IPY-ROAM expedition, recently visited Antarctica for a large series of measurements using the PP Systems UniSpec-DC Spectral Analysis System. The main purpose of the research was to address the question about the dependency of terrestrial ecosystems in Antarctica on the nutrient flow from the oceans. Vegetation reflectance measurements were made at many sites including Barrientos Island, Half Moon Island, Whaler’s Bay, Telefon Bay, Cuverville Island and Petermann Island. As expected, the weather conditions were quite harsh with temperatures ranging from 0-5o C and %RH ranging from 66-93%. Cloud cover was more than 80% at all field sites.
During this trip, researchers were able to obtain a rapid assessment of the antarctic shore-based ecosystem based on reflectance data obtained with the UniSpec-DC. They tried to correlate the reflectance properties of the landcover to other parameters such as vegetation cover, number of nesting penguin pairs close to the sampling site as well as other micromet data. Thank you to Santonu Goswami (Univ. of Texas-El Paso) and his colleagues for the pictures and reports from this most beautiful place.
Click here for more information on the UniSpec-DC.
If you would like to learn more about this exciting research, please contact PP Systems.