COS 26-5 - CO2 fluxes in two peatlands in the northern Andes are controlled by radiation and soil temperature

Tuesday, August 8, 2017: 9:20 AM
D132, Oregon Convention Center
Laura O. Gómez1, Juan Benavides2, Erik A. Lilleskov3, Rodney Chimner4 and John Hribljan4, (1)Biology, EAFIT University, Medellin, Colombia, (2)Ecology and Territory, Pontifical Xaverian University, Bogota, Colombia, (3)Climate, Fire and Carbon Cycle Sciences, US Forest Service, Northern Research Station, Houghton, MI, (4)Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI

Peatlands in the alpine area of the northern Andes (páramos) are common. They represent an important ecosystem where organic matter tends to accumulate because of the low temperatures, waterlogged habitat, and often under poorly aerated conditions. The main threats to peatlands are caused by changes in land use and climate change, because they are sensitive to environmental changes, shifting their role from sinks to carbon sources, and in the worst case to large methane emitters. We hypothesize that ecosystem production of peatlands in the Andes are mostly controlled by air temperature and radiation; and that ecosystem respiration is controlled by depth to the water table and soil temperature.


We measured CO2 fluxes using the closed chamber method for two years and monitored several variables we hypothesized were related. Net assimilation rates varied between -1.44 to 0.21 (mean -0.41) g CO2 m-2 h-1. Our results showed that in both locations Net Ecosystem Efficiency and gross plant primary production were related to photosynthetically active radiation and water vapor pressure deficit. Cloud cover was permanent reducing incoming radiation with a photosynthetic photon flux density varying between 178 to 1742 (mean 781) µmol m-2 s-1. Ecosystem Respiration (ER) varied between 0.01 and 1.14 g CO2 m-2 h-1 with marginal differences between both sites. ER variation was mostly related to soil temperature and depth to the water table. Night measurements showed a reduction of 70% of the diurnal ecosystem respiration. The two studied sites are net carbon sinks with an average of -0.05 and -0.02 g CO2 m-2 h-1 assimilated. Our study is the first one in the tropical Andes to analyze the CO2 exchange rates on this important ecosystem and has evidenced that changes in mean annual air temperature will have direct repercussions on soil respiration rates and thus on the carbon balance of the system. The broader implications of our research indicates that the sampled peatlands can shift from sinks to sources of CO2 with an increase of the soil temperature of 1 °C that at the current trends of warming of the troposphere is expected to happen in the next 25 years. We consider that our results will provide information for a sustainable and adaptive management of wetlands in the face of a changing global climate.