Fine root turnover in a northern hardwood forest: a direct comparison of the radiocarbon and minirhizotron methods

Tierney, Geraldine L.; Fahey, Timothy J.

doi:10.1139/x02-123

Cited by 114 publications

(149 citation statements)

References 17 publications

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“…However, measurements of isotopes in fine roots demonstrated that both the 14 C age (Gaudinski et al, 2001) and the incorporation rate of a continuous 13 C label (Matamala et al, 2003) in fine root C were inconsistent with an annual turnover. The various observations can be reconciled by assuming that fine roots are not a single homogeneous pool (Gaudinski et al, 2010;Guo et al, 2008;Strand et al, 2008;Tierney and Fahey, 2002;Trumbore, 2009). To date, published fine root radiocarbon ( 14 C) data are mostly from forest ecosystems and little is known of how these observations apply to non-forested ecosystems, or a range of forest types (Fröberg, 2012;Gaudinski et al, 2010;Riley et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Mean age of carbon in fine roots from temperate forests and grasslands with different management

et al. 2013

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Fine roots are the most dynamic portion of a plant’s root system and a major source of soil organic matter. By altering plant species diversity and composition, soil conditions and nutrient availability, and consequently belowground allocation and dynamics of root carbon (C) inputs, land-use and management changes may influence organic C storage in terrestrial ecosystems. In three German regions, we measured fine root radiocarbon (14C) content to estimate the mean time since C in root tissues was fixed from the atmosphere in 54 grassland and forest plots with different management and soil conditions. Although root biomass was on average greater in grasslands 5.1±0.8 g (mean±SE, n=27) than in forests 3.1±0.5 g (n=27) (p <0.05), the mean age of C in fine roots in forests averaged 11.3±1.8 yr and was older and more variable compared to grasslands 1.7±0.4 yr (p <0.001). We further found that management affects the mean age of fine root C in temperate grasslands mediated by changes in plant species diversity and composition. Fine root mean C age is positively correlated with plant diversity (r =0.65) and with the number of perennial species (r =0.77). Fine root mean C age in grasslands was also affected by study region with averages of 0.7±0.1 yr (n=9) on mostly organic soils in northern Germany and of 1.8±0.3 yr (n=9) and 2.6±0.3 (n=9) in central and southern Germany (p <0.05). This was probably due to differences in soil nutrient contents and soil moisture conditions between study regions, which affected plant species diversity and the presence of perennial species. Our results indicate more long-lived roots or internal redistribution of C in perennial species and suggest linkages between fine root C age and management in grasslands. These findings improve our ability to predict and model belowground C fluxes across broader spatial scales

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Section: Introductionmentioning

confidence: 99%

Mean age of carbon in fine roots from temperate forests and grasslands with different management

et al. 2013

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“…Fine roots play a major role in water and nutrient uptake, and fine root production and turnover are important processes in the carbon flow and nutrient cycling of terrestrial ecosystems (Gill and Jackson, 2000;Laclau et al, 2004;Lauenroth and Gill, 2003;Tierney and Fahey, 2002;West et al, 2004). Despite its importance in the water, carbon and nutrient balance of the ecosystem, fewer studies have been made of root * Corresponding author: daniel.epron@scbiol.uhp-nancy.fr growth than of the aboveground growth of trees in the field, because of methodological difficulties (Vogt et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Root elongation in tropical Eucalyptus plantations: effect of soil water content

et al. 2008

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-• Sustainability of Eucalyptus plantations is often questioned in resource-limited environments, especially in areas characterized by soils with poor nutrient and water holding capacities. Yet, field-based observations of fine root dynamics in relation with the seasonality of rainfall are lacking.• This study was undertaken on two Eucalyptus stands planted in the Kouilou Region (south-western Congo), which is characterized by a four-monthlong dry season. Fine root (less than 2 mm in diameter) dynamics were studied using rhizotron observations of root elongation in the field.• Fine root elongation rates displayed a seasonal variation in the two stands, with higher elongation rates during the rainy season than during the dry season. Positive and significant correlations were found between fine root elongation rates and soil water content at all depths, but a better correlation was found with soil water content in the deep soil horizon than in the superficial horizons.• These results suggest that the temporal variations in fine root elongation were related to the seasonality of rainfall, and they were probably associated with seasonal changes in tree water status, carbon assimilation and belowground allocation. fine roots / growth / rhizotron / Eucalyptus / soil water content Résumé -Élongation des racines dans les plantations tropicales d'Eucalyptus : effet du contenu en eau du sol.• La question de la durabilité des plantations d'Eucalyptus est souvent posée dans les environnements où les ressources sont limitées, en particulier les zones où les sols ont une faible capacité à retenir l'eau et les nutriments et où la saison sèche est longue. Pourtant, les observations in situ de la dynamique racinaire en relation avec la saisonnalité des pluies sont inexistantes.• Cette étude a été réalisée dans deux plantations d'Eucalyptus de la région du Kouilou dans le sud ouest du Congo, qui est caractérisée par quatre mois de saison sèche. La dynamique des racines fines (moins de 2 mm de diamètre) a été étudiée à l'aide de rhizotrons permettant d'observer l'élongation racinaire au champ.• La vitesse d'élongation des racines fines montrait une variation saisonnière dans les deux plantations, avec des vitesses plus élevées en saison des pluies qu'en saison sèche. Des corrélations positives et significatives ont été trouvées entre la vitesse d'élongation des racines fines et la teneur en eau du sol à toutes les profondeurs, mais les meilleures corrélations ont été observées avec la teneur en eau des horizons profonds.• Cela suggère que les variations temporelles de l'élongation des racines fines sont reliées à la saisonnalité des précipitations, et qu'elles sont associées aux changements saisonniers d'état hydrique des arbres, d'assimilation carbonée et d'allocation vers les parties souterraines. racines fines / croissance / rhizotron / Eucalyptus / teneur en eau du sol

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“…Radiocarbon analyses are criticised to overestimate fine root longevity mainly because of two reasons: the finest roots are likely to be underrepresented and new roots may be constructed with C from storage pools. Although sequential coring and minirhizotron observations usually yield fine root longevity estimates of less than one year, radiocarbon data indicate that tree fine roots live for more than 4 years on average (Gaudinski et al 2001;Tierney and Fahey 2002;Trumbore et al 2006).…”

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Estimating fine root longevity in a temperate Norway spruce forest using three independent methods

Gaul

Hertel

Leuschner

2009

Functional Plant Biol.

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Abstract. The importance of root systems for C cycling depends crucially on fine root longevity. We investigated mean values for fine root longevity with root diameter, root C/N ratio and soil depth using radiocarbon ( 14 C) analyses in a temperate Norway spruce [Picea abies (L.) Karst.] forest. In addition, we applied sequential soil coring and minirhizotron observations to estimate fine root longevity in the organic layer of the same stand. The mean radiocarbon age of C in fine roots increased with depth from 5 years in the organic layer to 13 years in 40-60 cm mineral soil depth. Similarly, the C/N ratios of fine root samples were lowest in the organic layer with a mean value of 24 and increased with soil depth. Roots >0.5 mm in diameter tended to live longer than those being <0.5 mm in diameter. By far the strongest variability in fine root longevity estimates was due to the chosen method of investigation, with radiocarbon analyses yielding much higher estimates (5.4 years) than sequential soil coring (0.9 years) and minirhizotron observations (0.7 years). We conclude that sequential soil coring and minirhizotron observations are likely to underestimate mean fine root longevity, and radiocarbon analyses may lead to an overestimation of mean root longevity.

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Fine root turnover in a northern hardwood forest: a direct comparison of the radiocarbon and minirhizotron methods

Cited by 114 publications

References 17 publications

Mean age of carbon in fine roots from temperate forests and grasslands with different management

Mean age of carbon in fine roots from temperate forests and grasslands with different management

Root elongation in tropical Eucalyptus plantations: effect of soil water content

Estimating fine root longevity in a temperate Norway spruce forest using three independent methods

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