A new automated stem CO2 efflux chamber based on industrial ultra-low-cost sensors. (13th December 2019)

• Record Type: Journal Article
• Authors: Brändle, Johannes; Kunert, Norbert
• Editors: Palmroth, Sari
• Is Part Of: Tree physiology. Volume 39:Number 12(2019)
• Page Start: 1975
• Page End: 1983
• Publication Date: 2019-12-13
• Subjects: Arduino -- autotrophic respiration -- ecosystem respiration -- high temporal resolution data -- long-term measurements -- microcontroller; Trees -- Physiology -- Periodicals; 582.16
• DOI: 10.1093/treephys/tpz104
• Languages: English
• ISSNs: 0829-318X

Abstract

Abstract: Tree autotrophic respiratory processes, especially stem respiration or stem CO2 efflux ( E stem ), are important components of the forest carbon budget. Despite efforts to investigate the controlling processes of E stem in recent years, a considerable lack in our knowledge remains on the abiotic and biotic drivers affecting E stem dynamics. It has been strongly advocated that long-term measurements would shed light onto those processes. The expensive scientific instruments needed to measure gas exchange have prevented E stem measurements from being applied on a larger temporal and spatial scale. Here, we present an automated closed dynamic chamber system based on inexpensive and industrially broadly applied CO2 sensors, reducing the costs for the sensing system to a minimum. The CO2 sensor was cross-calibrated with a commonly used gas exchange system in the laboratory and in the field, and we found very good accordance of these sensors. We tested the system under harsh tropical climatic conditions, characterized by heavy tropical rainfall events, extreme humidity and temperatures, in a moist lowland forest in Malaysia. We recorded E stem of three Dyera costulata (Miq.) trees with our prototype over various days. The variation of E stem was large among the three tree individuals and varied by 7.5-fold. However, clear diurnal changes in E stem were present in all three tree individuals. One tree showed high diurnal variation in E stem, and the relationship between E stem and temperature was characterized by a strong hysteresis. The large variations found within one single tree species highlight the importance of continuous measurement to quantify ecosystem carbon fluxes.