Stem and soil respiration in fertilised plots in the Central Amazon, 2017-2019

Measurements of stem respiration (ppm) were performed on 320 trees with DBH > 25 cm, with 10 trees in each plot, during October 2019. CO2 stem efflux was measured with an infrared gas analyser (EGM-4, PP systems), where a chamber was placed on to a collar installed in the tree, and detected the rate of CO2 accumulation for a period of two minutes. The collar was sealed with a special glue, and inspections with a flashlight were made to check for any holes B) An EGM-4 portable Infra Red Gas Analyser (IRGA) right and the chamber (left) for measurement of CO2 efflux. We also measured soil respiration rates (autotrophic and heterotrophic) using the Li – 8100A soil respiration system (Li-cor, Lincoln, NE, USA), equipped with a 20 cm survey chamber (Model:8100-101). The equipment was set up to an observation length of 1 minute and 30 seconds, and the pre purge and pos purge to 10 seconds.