Comparison of litter-bag and chamber methods for measuring CO₂ emissions from leaf litter decomposition in a temperate forest

Abstract

Leaf litter decomposition strongly affects the global carbon cycle through carbon dioxide CO 2 emissions to the atmosphere. The litter bag method LB and chamber method with litter addition and removal treatments C-LART have been used to quantify the litter decomposition rate and its resultant CO 2 flux. The C-LART method measures soil CO 2 fluxes in control, litter addition, and litter removal plots, and thereby decomposition rates are calculated from differences of the fluxes. However, no report has described the applicability of C-LART in comparison with LB. This study measured the litter decomposition rate and its resultant CO 2 flux using C-LART and LB in a temperate evergreen forest in central Japan to assess the applicability of the two methods. Annual soil respiration in the control plot was 1572 gC m 2 yr 1 , which was approximately twice as high as the mean of temperate evergreen forests in the world. The litter decomposition rate was 0.42 g g 1 yr 1 in mass loss or 0.49 gC gC 1 yr 1 in carbon loss by LB, which are compatible with those reported from other temperature forests. In contrast, the decomposition rate of litter carbon ascertained using C-LART was greater than 1 1.96 -3.76 gC gC 1 yr 1 , meaning that carbon emissions increased more than applied, and that the carbon emissions were decreased more than those removed by litter treatments. The incredibly high decomposition was attributed to the enhanced or restricted microbial activities in the underlying mineral soil. Changes in microbial activity are probably caused by the alteration of material supply from the leaf litter layer to the soil by litter treatment the priming effect . In conclusion, C-LART is not applicable to evaluate CO 2 emissions through litter decomposition. Another approach must be used to compensate the priming effect for application of the chamber method.

Soil carbon flux research in the Asian region: Review and future perspectives

“…However, the downside to the open-top chamber method was that it tends to be influenced by wind Table 1, Fang and Moncrieff, 1998;Liang et al, 2004 . The application of the closed dynamic chamber to measure R s was a relatively recent development compared with the other chamber methods Hall et al, 1990;Rochette et al, 1991; The popularisation of the compact IRGA had greatly influenced the applicability of the closed dynamic method and several types of dynamic chamber methods to measure R s Rochette et al, 1997 . In this method, only the air sample collected in the closed chamber is led into the CO 2 analyser with no ambient air flow into the chamber Rochette et al, 1997 . The measurement is conducted in a non-steady state under increasing CO 2 concentrations inside the chamber due to R s . There are several commercial portable-type closed dynamic chamber systems such as the Li6400 equipped with a soil respiration chamber 6000 -09, Li-cor, Lincoln, NE, USA , Li8100 Li-cor , or EGM-5 equipped with a soil respiration chamber SRC-2, PP-Systems, Amesbury, MA, USA ; many studies have used these systems Wang et al, 2005;Ohashi et al, 2008;Adachi et al, 2009;Liu et al, 2016a;Li et al, 2019b;Qin et al, 2019 . In recent research, the originally developed portable-type closed dynamic chamber systems have also been used in the field Takada et al, 2015;Sun et al, 2017;Gao et al, 2019;Zhao et al, 2021 .…”

“…Typical Q 10 values of R s are roughly in the range of 2.0 -3.0, based on previous observational studies that have largely taken place in relatively humid Asian regions covering sub-tropical forests, and temperate forests Tan et al, 2013;Noh et al, 2017;Sun et al, 2017;Teramoto et al, 2017 . In the meta-analysis presented in Wang et al 2010 , worldwide observations mainly from forests showed that the arithmetic mean of the Q 10 value was 2.67, despite a large variation in the Q 10 values from 0.98 to 6.27. These observed Q 10 values tend to be higher compared to global estimates of Q 10 .…”

Partitioning of root respiration into growth, maintenance, and ion uptake components in a young larch-dominated forest

“…Soil CO2 flux was measured on each collar using a previously described method (Cui et al 2021;Sun et al 2017) between 10:00 and 16:00 at intervals of approximately three weeks from August 2019 through November 2020 with a five-month suspension from mid-November 2019 through mid-April 2020. Seedlings were carefully pulled from the collars before flux measurements, although they were rarely found.…”

Fine root dynamics and partitioning of root respiration into growth and maintenance components in cool temperate deciduous and evergreen forests

“…Before the treatments, CO2 efflux was also measured in September and October 2014 to check for initial spatial variations among the CC, SC, LC, and TC collars. The measurements were conducted manually on each collar between 10:00 and 16:00 using a closed chamber system with two 50 cm tall cubic chambers made of transparent acrylic plastic (Sun et al 2017). CO2 concentration and air temperature inside the chamber were measured every 5 s with an infrared gas analyzer (LI820; Li-Cor Inc., Lincoln, NB, USA) and a thermocouple probe (MHP; Omega Engineering, Stamford, CA, USA).…”