A comparison of methods for converting rhizotron root length measurements into estimates of root mass production per unit ground area

Metcalfe, Daniel B.; Meir, Patrick; Williams, Mathew

doi:10.1007/s11104-007-9447-6

Cited by 31 publications

(27 citation statements)

References 28 publications

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“…This is an inherent bias of the method leading to an overestimation of the fine root elongation rate. In some species, a certain period is required before the beginning of measurements (generally 3 months) to attain equilibrium in new root growth after rhizotron installation (Green et al, 2005;Metcalfe et al, 2007). In Eucalyptus however, a previous study of the effect of mechanical weeding on root development showed that few roots were formed at a wound (Bouillet et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

“…Care was taken to select trees with straight boles in a clean area with no dead trees in their immediate vicinity. Fine root dynamics were monitored using rhizotrons (Jourdan and Rey, 1997;Green et al, 2005;Metcalfe et al, 2007;Sword, 1998). Square panes of glass (0.9 × 0.9 m) were set up at a distance of about 1.5 m from the tree.…”

Section: Rhizotronmentioning

confidence: 99%

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

et al. 2008

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“…The most common methods, such as ingrowth cores or sequential coring [60], involve the extraction and weighing of fine roots. Alternatively, roots can be observed with rhizotrons [61], which are typically regions of soil covered by clear plastic or glass in which new root growth can be measured at regular intervals. These techniques may underestimate fine root NPP owing to fine root herbivory or turnover of roots faster than the interval at which they are measured, or through soil disturbance effects if the measurement results in changes in the soil environment that inhibit fine root growth.…”

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confidence: 99%

The allocation of ecosystem net primary productivity in tropical forests

Malhi

Doughty

Galbraith

2011

Phil. Trans. R. Soc. B

357

374

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The allocation of the net primary productivity (NPP) of an ecosystem between canopy, woody tissue and fine roots is an important descriptor of the functioning of that ecosystem, and an important feature to correctly represent in terrestrial ecosystem models. Here, we collate and analyse a global dataset of NPP allocation in tropical forests, and compare this with the representation of NPP allocation in 13 terrestrial ecosystem models. On average, the data suggest an equal partitioning of allocation between all three main components (mean 34 + 6% canopy, 39 + 10% wood, 27 + 11% fine roots), but there is substantial site-to-site variation in allocation to woody tissue versus allocation to fine roots. Allocation to canopy (leaves, flowers and fruit) shows much less variance. The mean allocation of the ecosystem models is close to the mean of the data, but the spread is much greater, with several models reporting allocation partitioning outside of the spread of the data. Where all main components of NPP cannot be measured, litterfall is a good predictor of overall NPP (r 2 ¼ 0.83 for linear fit forced through origin), stem growth is a moderate predictor and fine root production a poor predictor. Across sites the major component of variation of allocation is a shifting allocation between wood and fine roots, with allocation to the canopy being a relatively invariant component of total NPP. This suggests the dominant allocation trade-off is a 'fine root versus wood' trade-off, as opposed to the expected 'root-shoot' trade-off; such a trade-off has recently been posited on theoretical grounds for old-growth forest stands. We conclude by discussing the systematic biases in estimates of allocation introduced by missing NPP components, including herbivory, large leaf litter and root exudates production. These biases have a moderate effect on overall carbon allocation estimates, but are smaller than the observed range in allocation values across sites.

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“…The magnitude of the difference in fine root standing crop between sites was still unexpected. Our method of using a standard depth of field for minirhizotron methods may have over-estimated standing root crop compared to other methods such as the plane-intersect (Metcalfe et al, 2007). However, the relative relationship between the two sites would still hold since the same method was used for both sites.…”

Section: Discussionmentioning

confidence: 95%

Fine root dynamics of trembling aspen in boreal forest and aspen parkland in central Canada

et al. 2010

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Keywords: minirhizotron / Populus tremuloides / root length / fine root biomass / root turnover Abstract • Fine root responses to potential climate change are relatively unknown in spite of their central role in ecosystem functioning.• We quantified fine root length, production, and turnover in boreal forest and aspen parkland of central Canada because the future climate of the boreal site is expected to be similar to the current climate of the parkland site.• Root depth distribution and turnover were similar between sites. Fine root mass was 4× greater at the parkland site and root length was 10× greater. Accordingly, the ecosystem level fine root: leaf mass ratio was 1.6 in the boreal site compared to 4.3 in the parkland site. On a per tree basis, however, fine root biomass was similar between sites due to the higher stem density of the parkland site.• The parkland site had a greater proportion of very fine roots (62% of the fine roots were < 0.1 mm in diameter) compared with the boreal site (82% of the fine roots were between 0.1-0.5 mm in diameter).• These differences indicate a large-scale shift towards increased root allocation at the parkland site associated with decreasing water availability and earlier successional stage.

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A comparison of methods for converting rhizotron root length measurements into estimates of root mass production per unit ground area

Cited by 31 publications

References 28 publications

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

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

The allocation of ecosystem net primary productivity in tropical forests

Fine root dynamics of trembling aspen in boreal forest and aspen parkland in central Canada

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