Some characteristics of soil respiration in hybrid poplar plantations in northern Alberta

Abstract

. 2006. Some characteristics of soil respiration in hybrid poplar plantations in northern Alberta. Can. J. Soil Sci. 86: 257-268. Fast-growing hybrid poplars are being planted in the Canadian prairies to meet the increasing demand for fibre and environmental services of trees and forests; however, the impact of hybrid poplars on C dynamics and storage on previously farmed land is largely unknown for the boreal region. We measured soil CO 2 efflux along a chronosequence (3-, 9-, and 11-yr-old stands) of hybrid poplar (Populus deltoides × Populus × petrowskyana var. Walker) plantations and a control agricultural field from June to August 2004. Measurements were made between 0800 and 1800 with a portable Li-Cor 6400-09 system and were based on 4-5 min averaging. We also measured the response to simulated rainfall and the diurnal fluctuation of soil CO 2 efflux. Soil CO 2 efflux ranged from 1.30 µmol CO 2 m -2 s -1 in the 3-yr-old plantation to 5.41 µmol CO 2 m -2 s -1 in the agricultural control field, or from 0.17 µmol CO 2 m -2 s -1 kg -1 C (based on soil organic C content to a 0.4 m depth) in the 3-yr-old plantation to 1.09 µmol CO 2 m -2 s -1 kg -1 C in the 11-yr-old plantation. Simulated rainfall applied in the 3-yr-old plantation and a newly planted site resulted in an immediate pulse of CO 2 efflux, 2.90 and 2.54 µmol CO 2 m -2 s -1 , respectively, followed by an efflux rate sustained slightly above pre-irrigation levels. No secondary pulse of soil respiration was observed in the 2-h period following water application. Diurnal variation of soil respiration was found to be small between 0600 and 1900 in the agricultural control field, with values that varied from 2.66 to 3.17 µmol CO 2 m -2 s -1 . Continued monitoring of soil respiration and other C cycling processes in the chronosequence will improve our understanding of the potential for C sequestration in hybrid poplar plantations in northern Alberta. Les auteurs ont aussi mesuré la réaction à une pluie artificielle et la fluctuation diurne des efflux de CO 2 du sol. Ces derniers varient de 1,30 µmol de CO 2 par m 2 et par seconde pour la plantation de trois ans à 5,41 µmol pour la culture témoin, ou de 0,17 µmol de CO 2 par m 2 et par seconde, par kilo de C (teneur du sol en C organique à 0,4 m de profondeur), pour la plantation de trois ans à 1,09 µmol pour celle de onze ans. La pluie artificielle a immédiatement entraîné un efflux de CO 2 de 2,90 et de 2,54 µmol par m 2 et par seconde dans la plantation de trois ans et dans une nouvelle plantation, respectivement. Cette réaction a été suivie par un efflux stable, légèrement supérieur à celui observé avant l'irrigation. Aucun signe de respiration secondaire du sol n'a été observé au cours des deux heures qui ont suivi l'arrosage. La respiration du sol varie peu durant le jour, entre 6 h et 19 h, dans le champ cultivé, les valeurs fluctuant de 2,66 à 3,17 µmol de CO 2 par m 2 et par seconde. En poursuivant l'étude de la respiration du sol et d'autres processus du cycle du carbone dans cette chronoséquence...

Temporal changes in soil carbon and nitrogen storage in a hybrid poplar chronosequence in northern Alberta

“…There were no differentiated L, F or H horizons in any of the studied stands. This was attributed to site maintenance activities (disking and mowing) of the plantations which is done for the first 3 to 4 years, and to a very small amount of litter fall input especially in the young stands, and a relatively fast rate of litter decomposition (Saurette et al, 2006).…”

“…The Al-Pac mill site (54°49′ N and 113°31′ W, 626 m ASL) is located about 200 km north of Edmonton. A detailed description of the 2-, 5-, 11-and 13-yearold stands (age as in 2006) selected for study is provided in Saurette et al (2006). Briefly, mean annual temperature of the site is 2.1°C and mean annual precipitation is 503.4 mm, of which one-third falls as snow.…”

“…The dominant soil type in the area is Luvisolic soils. The selected stands had high natural variability in organic C and N contents (Saurette et al, 2006).…”

Autotrophic and heterotrophic respiration rates across a chronosequence of hybrid poplar plantationsin northern Alberta

“…Within each stand, two 1 )1 m plots were established in mid-May 2005: one control plot and one root excluded (trenched) plot. The plots (control and trenched) were all placed systematically between four tree stems (ranging between 2.5 ) 2.5 and 3)3 m grid spacings) in each stand to avoid inducing error in soil respiration measurements resulting from variations caused by stand tending practices (Saurette et al 2006). Trenches were installed to a depth of 40 cm, as most of the root biomass and activity occur in the soil above this depth.…”

Characteristics of CO2 release from forest soil in the mountains near Beijing

“…The CO 2 release from soil has been measured in various ecosystems including farm lands (Hernandez-Ramirez et al 2009), forests (Gaelle et al 2006;Saurette et al 2006), and grasslands but evaluations with forest soils have usually been conducted in the laboratory (Jiang and Hong 1997). The CO 2 release from forest soils in China has seldom been measured in situ (Liu et al 1998;Zhou 2003) and has never been measured in forest soils in the mountains near Beijing, which are in the boreal temperate region.…”