Carbon dioxide emission derived from soil organic matter decomposition and root respiration in Japanese forests under different ecological conditions

Abstract

Soil chambers with 3 types of soil treatment were used to analyze the environmental factors controlling carbon dioxide (CO 2 ) emission in forest soils of Japan and to separately determine CO 2 emission from root respiration, microbial decomposition of organic matter in the O layer and in the mineral soil layers. Soil chambers were installed at the Kyoto, Miyazu-Oak, Miyazu-Cedar, Miyazu-Beech and Nobeyama sites; the sites differed from each other in soil temperature, vegetation and parent materials. The soil treatments applied at each of the 5 sites were as follows: (1) control plot, (2) O-plot with removal of the O layer, (3) root-plot with the suppression of root respiration by inserting the chambers to a depth of 20 cm and sealing the bottom. The CO 2 emission levels at all sites were significantly correlated with soil temperature, but not with soil moisture levels. The annual rates of soil organic matter decomposition simulated based on the automatically recorded soil temperature were 5.1, 4.0, 5.2, 5.5 and 3.4 Mg C ha −1 at the Kyoto, Miyazu-Oak, Miyazu-Cedar, Miyazu-Beech and Nobeyama sites, respectively. These rates were influenced by soil temperature, litter fall rates and the carbon stocks. In contrast, the ratio of the annual rate of root respiration to the annual rate of soil respiration decreased as soil temperature decreased. Based on the carbon budget, the Miyazu-Cedar and Nobeyama sites appeared to have lost their soil carbon stock. For more accurate analysis, methods for the direct measurement of the input rate of root litter should be developed.

Biometric-based estimation of net ecosystem production in a mature Japanese cedar (Cryptomeria japonica) plantation beneath a flux tower

“…Thus, direct sampling using cut roots might yield large errors in the estimation of root respiration. In our study, root respiration accounted for about 47.8% of soil respiration, which was similar to that reported in a mature Japanese cedar plantation (44%) by Shinjo et al (2006) who used a trenching method. Our estimation also agreed with the average values in forest ecosystems (46%) reported by Hanson et al (2000).…”

Fluxes of dissolved organic carbon and nitrogen throughout Andisol, Spodosol and Inceptisol profiles under forest in Japan

“…2). Production of DOC (litter solubilization) depends on microbial activities, which are enhanced by temperature (Gö dde et al 1996, Shinjo et al 2006). On the other hand, mineralization of DOC is unaffected by temperature because of the limited ability of microorganisms to mineralize DOC (Gö dde et al 1996).…”

“…3), the C stocks of the O C, carbon; N, nitrogen; DIN, dissolved inorganic nitrogen; TDN, total dissolved nitrogen; O, organic; NG, Nagano; TG, Tango; KT, Kyoto. The data of OM decomposition rates were cited from Shinjo et al (2006). The stocks of C and N in soil at the depths of 0 to 45 cm were counted.…”

“Fallow Band System,” a land management practice for controlling desertification and improving crop production in the Sahel, West Africa. 1. Effectiveness in desertification control and soil fertility improvement

“…Eleven measurements were carried out in the morning (between 8:15 and 10:00) throughout the cropping season. Because soil respiration consists of both plant-root respiration and microbial respiration, plant-root respiration was excluded using the trenching method reported by Shinjo et al (2006). In May 2008 (before sowing), four polyvinylchloride cylinders (diameter, 0.15 m; length, 0.25 m) were inserted into the soil to a depth of 0.12 m in the cultivated band, whereas eight cylinders (diameter, 0.15 m; length, 0.30 m) were inserted to a depth of 0.17 m in the former fallow band, because wind-blown sediments were deposited on the former band and the surface elevation appeared to increase by approximately 0.05 m. The enclosed soil was later supported with a fine stainless steel wire mesh at the bottom of the cylinders.…”