Development of an automatic chamber system for long-term measurements of CO₂ flux from roots

Abstract

A B S T R A C TTo separate CO 2 efflux from roots (R r ) and soil (R s ), we developed a system to measure R r continuously. Using this system, seasonal variation in R r was obtained in a temperate forest in Japan. We measured R s , CO 2 efflux from mineral soil (R m ) and environmental factors simultaneously, and the characteristic and seasonality of R r were analysed in comparison with R s . R r and R s showed different responses to soil water content: R s decreased with decreasing soil water content, whereas R r peaked at relatively low soil water content. R r /R s decreased from 64.8% to 27.3% as soil water content increased from 0.075 to 0.225 cm cm −3 . The relationship between respiration and temperature appears to change seasonally in response to phenological and biological factors. R r showed clear seasonal variation as a function of soil temperature. During the growing period, R r exhibited a higher rate at the same soil temperature than during other periods, which may be due to phenological influences such as fine root dynamics. R s decreased during the summer despite high soil temperatures. The seasonal peak for R s occurred earlier than that for soil temperature. R r /R s ranged between 25% and 60% over the course of the year.

It’s Complicated: Intraroot System Variability of Respiration and Morphological Traits in Four Deciduous Tree Species

“…However, for RR SA and RR VOL (Supplemental Fig. S2), which are rather rarely calculated (Asplund and Curtis, 2001;Desrochers et al, 2002;Dannoura et al, 2006aDannoura et al, , 2006b), significant influences of root diameter were found. RR is dependent on tissue porosity to gas diffusion (Asplund and Curtis, 2001); therefore, it can be anticipated that increasing diameter will increase diffusional limitations in tissues and alter respiration kinetics.…”

“…Root respiration (RR) accounts for 25% to 60% of total soil respiration (Pregitzer et al, 1997;Epron et al, 1999;Dannoura et al, 2006aDannoura et al, , 2006b) and consumes up to 75% of carbon allocated to roots (Majdi et al, 2007). Predictions on whole-plant carbon budget estimate that total plant respiration is about one-half of gross primary production (Chapin et al, 2012).…”

Effects of environmental factors and soil properties on topographic variations of soil respiration

“…Soil respiration rates are affected by environmental factors such as soil moisture and soil temperature and by soil properties such as root biomass and porosity (Hanson et al, 2000;Dannoura et al, 2006). Therefore, both environmental factors and soil properties can affect topographic variation in soil respiration.…”

Fine Root Dynamics and Root Respiration

“…The advantage of intact root method is that continuous measurement of respiration could be compared with environmental factors. Respiration rates of intact roots have been measured in the laboratory, by placing plant pots in chambers (Dannoura et al 2005;Edwards 1991), as well as in the field (Dannoura et al 2006a;Chen et al 2009). …”