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

Abstract

. 2008. Autotrophic and heterotrophic respiration rates across a chronosequence of hybrid poplar plantations in northern Alberta. Can. J. Soil Sci. 88: 261Á272. Distinction of autotrophic (root, R r ) versus heterotrophic (R h ) soil respiration is important to understanding C balance in forest ecosystems and the contribution of both respiration components to total soil respiration (R s ) may change as stands mature. We studied R r and R h in a chronosequence of hybrid poplar plantations that were 4, 6, 8, and 13 yr old in summer 2005. We hypothesized that R r will become increasingly larger and will also represent a greater proportion of R s as plantation age increases. Our results showed that both R s and R h showed significant seasonal variations; however, R r were much more variable. No significant differences among plantation ages were observed for any of the respiration parameters (R r , R h and R s ) measured throughout the summer. No significant differences were found for the contribution of R h to R s between plantation ages or between sampling dates. The average proportion of R h to R s across all sites and sampling dates was 0.6390.026 (mean9standard error), indicating that heterotrophic respiration dominated total soil respiration in the studied hybrid poplar plantations. The power of the statistical tests in this study was likely quite low due to the inclusion of only two replicates for each plantation age.Key words: Autotrophic, heterotrophic respiration, root exclusion, trenching, hybrid poplar, chronosequence Saurette, D. D., Chang, S. X. et Thomas, B. R. 2008. Taux de respiration autotrophe et he´te´rotrophe dans une chronose´quence de peupliers hybrides dans le nord de l'Alberta. Can. J. Soil Sci. 88: 261Á272. Pour mieux comprendre le bilan du carbone dans les e´cosyste`mes forestiers, il importe de faire la distinction entre la respiration autotrophe (racines, R r ) et he´te´rotrophe (R h ) du sol, deux composantes dont l'apport a`la respiration totale (R s ) peut changer avec l'e´volution du peuplement. Les auteurs ont examine´la R r et la R h dans une chronose´quence de peupliers hybrides de 4, 6, 8 et 13 ans durant l'e´te´2005. Ils ont e´mis l'hypothe`se que la R r ne cesserait d'augmenter et repre´senterait une part de plus en plus grande de la R s avec le vieillissement du peuplement. Les re´sultats indiquent que la R s et la R h varient sensiblement avec la saison; mais que la R r le fait davantage. Aucun des parame`tres de la respiration (R r , R h et R s ) quantifie´s durant l'e´te´ne fluctue sensiblement avec l'aˆge du peuplement. La contribution de la R h a`la R s ne varie pas e´norme´ment avec l'aˆge du peuplement ni la date d'e´chantillonnage. La R h repre´sente une proportion de 0,6390,026 (moyenne9erreur-type) de la R s pour l'ensemble des sites et des dates d'e´chantillonnage, signe que la respiration he´te´rotrophe dominait dans les plantations de peupliers hybrides examine´es. Les tests statistiques employe´s dans le cadre de cette e´tude n'ont qu'une valeur relativement faibl...

Soil CO2 effluxes, temporal and spatial variations, and root respiration in shrub willow biomass crops fields along a 19‐year chronosequence as affected by regrowth and removal treatments

“…Saurette et al . (, ) reported F c rates, ranging from 1 to 5 μmol m −2 s −1 for 3‐ to 11‐year‐old hybrid poplar plantations. In a 15‐year‐old hybrid poplar plantation, intercropped with agricultural crops, Peichl et al .…”

“…and Acer spp. (Cisneros‐Dozal et al ., ), 60% for beech stand ( Fagus sylvatica ) (Epron et al ., ), 56% for Pinus sylvestris L. (Högberg et al ., ), 47% (Saurette et al ., ), and 65–85% for a hybrid poplar (Arevalo et al ., ). These studies, however, measured root respiration during the growing season only.…”

Soil heterotrophic respiration in Casuarina equisetifolia plantation at different stand ages

“…Saurette et al (2008) reported that there was no significant difference of R h between plantations at different growth ages. However, the significant difference of R h was found in this study (p<0.05), the R h was highest in the middle-age plantation and then followed by the mature plantation.…”

“…Most of the previous studies about R h focus on the inland forest ecosystems (Hanson et al 2000;Ngao et al 2007;Saurette et al 2008;Gaumont-Guay et al 2008), and very few concerns coastal forest (Tyree et al 2006). As so far, no available information has been found on R h in coastal forest ecosystem in China.…”

Evaluation of Multiple Spring Phenological Indicators of Yearly GPP and NEP at Three Canadian Forest Sites

“…NEP also depends on stand age (i.e., different amplitudes in R e ), and given the mature and old forest sites examined in this study, our findings may not be applicable to young forests and other ecosystems (e.g., crops, grasslands). Because the components of soil respiration differ among forests of various ages [42,43], caution should be used when applying our results to young forests. Therefore, further analysis and evaluation would facilitate extension of our results to more ecosystems in diverse ecoregions.…”