Microbial drivers of N2O emissions in the Biosphere 2 Tropical Rainforest
Post by Juliana Young
The Rainforest at Biosphere 2 is a unique study system because it operates under very high temperatures and has adapted to the Arizona heat. In 2002, Dr. Joost van Haren studied nitrous oxide (N2O) flux in the Rainforest at Biosphere 2 and found that there is a high and low pulse zone of emissions of this gas under the condition of post-drought (van Haren et al., 2005). Our study builds from the foundations of this experiment. We are testing what could be responsible for the spatial difference in N2O gas fluxes. While there are many facets of the Rainforest to study, my interests and area of research focuses on the climatic parameter of drought and rewetting responses of the microbial community in the soil of the Rainforest. Currently, with the help of Dr. Laura Meredith and Dr. Aditi Sengupta, I am characterizing the soil microbial communities of the Rainforest and how their abundance or metabolism can be related to the N2O gas flux.
Our data includes five sites and 3 depths at each site in the Rainforest that were sequenced using 16S rRNA gene for bacteria and archaea and ITS2 for fungi. We consider these data alongside edaphic factors like soil moisture, average pH, average electric conductivity, total carbon, total nitrogen and carbon to nitrogen ratio and gas fluxes including nitrous oxide, methane, and carbon dioxide concurrently collected during the 60-day experiment. Current analysis is focused on linking microbial metabolism or abundance to pulses in nitrous oxide in the Rainforest at Biosphere 2. Correlations between abiotic factors are also being related to microbial communities within each specific sampling site.
Tropical environments generate a lot of the Earth’s nitrous oxide through biogeophysical processes that are not well understood; therefore, studying the microbes and nitrous oxide emissions could potentially give insight into the complexity of this greenhouse gas. To complement our current data, we are planning metagenomic or targeted amplicon sequencing for genes that are shown to be highly conserved for nitrification and denitrification in our original samples or a new drought experiment to explain the microbial drivers of high and low N2O pulse regions.
