Canopy Chamber: a useful tool to monitor the CO2 exchange dynamics of shrubland

Abstract

A transient state canopy-chamber was developed to monitor CO2 exchange of shrubland ecosystems. The chamber covered 0.64 m 2 and it was modular with a variable height. Several tests were carried out to check the potential errors in the flux estimates due to leakages and the environment modifications during the measurements inside the chamber. The laboratory leakages test showed an error below 1% of the flux; the temperature increases inside the chamber were below 1.3 °C at different light intensity and small pressure changes. The radial blowers inside the chamber created different wind speed at different chamber height, with faster speed at the top of the chamber and the minimum wind speed that was recorded at soil level, preventing detectable effects on soil CO2 emission rates. Moreover, the chamber was tested for two years in a semi-arid Mediterranean garrigue, identifying a strong seasonality of CO2 fluxes with the highest rates during spring and lowest rates recorded during the hot dry non-vegetative summer.

On the calculation of daytime CO2 fluxes measured by automated closed transparent chambers

“…The selection of observation time for chamber measurements was empirical in the literature. For instance, the observation length of CO 2 flux estimation ranged between 1.5 min to 10 min (Wohlfahrt et al, 2005; Kutzbach et al, 2007; Savage et al, 2008; Koskinen et al, 2014; Görres et al, 2016; Guidolotti et al, 2017; Kostyanovsky et al, 2018), and that of other green house gases such as CH 4 and N 2 O ranged between 10 min to 25 min (Hendriks et al, 2007; Kroon et al, 2008; Savage et al, 2014). Most of the published studies on chamber CO 2 flux measurements were taken with dark chambers or at night for only ecosystem respiration.…”

Enhancement of ecosystem carbon uptake in a dry shrubland under moderate warming: The role of nitrogen‐driven changes in plant morphology

“…With no significant effect recorded in SR, and a limited (not significant) increase in TER, NEE stimulation mainly depended on the higher GP of vegetation in the NEE collars. Gross photosynthesis displayed strong seasonality, being lowest during the summer dry period and highest in spring and autumn (Guidolotti et al, 2017 ). The warming effect was restricted to these periods of optimal environmental conditions, and therefore did not depend on a different response to the summer aridity triggered by the temperature increase.…”

“…Shrubland CO 2 exchange was measured using transparent canopy chambers fitted with square NEE soil collars (0.64 m 2 ) connected to an LI‐8100 infrared gas analyzer (LI‐COR Biosciences, Inc.), following Guidolotti et al ( 2017 ). Two NEE collars were installed in each plot (six per treatment) during winter 2009, after 8 years of continuous temperature manipulation.…”

Developing an Automated Gas Sampling Chamber for Measuring Variations in CO2 Exchange in a Maize Ecosystem at Night

“…If there is no climate regulation, it is more difficult to maintain the temperature change in the closed chamber in the range of 2 • C [1]. Through research, Gabriele developed a dynamic closed chamber that can effectively monitor the CO 2 exchange dynamics of bushes [21]. The coverage area of the chamber is 0.64 m 2 (length and width are 0.8 × 0.8 m).…”

“…Droesler [6] used the dynamic closed chamber method to measure NEE of bog and their research showed that the maximum change of humidity during the measurement period reaches 20%. The relative humidity increase in the chamber designed by Gabriele [21] ranged between 4 and 20% in the CO 2 exchange measurement period, and the average value of humidity increase was 13%. Due to the use of the humidity control system, the maximum humidity change in the chamber developed in this study was 5.6% in the experiments.…”