Age-related equations for above- and below-ground biomass of a Eucalyptus hybrid in Congo

Saint‐André, Laurent; M’Bou, Armel Thongo; Mabiala, André; Mouvondy, Welcome J.; Jourdan, Christophe; Roupsard, Olivier; Deleporte, Philippe; Hamel, Olivier; Nouvellon, Yann

doi:10.1016/j.foreco.2004.10.006

Cited by 165 publications

(119 citation statements)

References 19 publications

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“…Both were in the second planting cycle. They were first planted on burned savannah, then coppiced and planted again after clear-cutting at a spacing of 3.2 m × 3.8 m for the 9-month-old stand and at a spacing of 3.0 m × 4.7 m for the 2-year-old stand (Epron et al, 2004;Saint-André et al, 2005). Both received starter fertilization (150 g of NPK 13-13-21 per tree) and herbaceous vegetation was chemically controlled.…”

Section: Site Descriptionmentioning

confidence: 99%

“…They are managed in short rotations, but the sustainability of these highly productive plantations is often questioned in resourcelimited environments, especially in areas characterized by soils with poor nutrient and water holding capacities and by a long dry season like the Kouilou Region in southern Congo. Up to now, studies of Eucalyptus root systems have involved a static description of root distribution and quantification of biomass Laclau et al, 2001;Mello et al, 2007;Moroni et al, 2003;O'Grady et al, 2006;Saint-André et al, 2005;Stape et al, 2004). However, fewer investigations have been made of the environmental control of root dynamics (Fabião et al, 1985;Kätterer et al, 1995).…”

Section: Introductionmentioning

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: Site Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2008

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“…Alternatively, biomass expansion factors can also be used (Lehtonen et al 2004;Longuetaud et al 2013). Since the early 1970s, many biomass equations have been established for a wide variety of tree species in different regions of the world (Ter-Mikaelian and Korzukhin 1997; Nelson et al 1999;Lambert et al 2005;Saint-André et al 2005;Wutzler et al 2008). Nevertheless, the users of these biomass equations are generally facing several problems:…”

Section: Introductionmentioning

confidence: 99%

“…While biomass studies often relied on limited numbers of sites and trees in the past, some biomass data from various sources were recently pooled together to obtain large data sets, which therefore broadened the validity range of the biomass equations established based on these data (Wutzler et al 2008). In addition, when a lot of data are available, a subset can be devoted to validation in order to independently evaluate model performances (Saint-André et al 2005;Wutzler et al 2008;Genet et al 2011). The use of covariate models is another way to improve the validity range of biomass equations; this approach consists in fitting biomass equations site by site (or stand by stand) and to relate equation parameters to site/stand variables (Saint- André et al 2005;António et al 2007;Genet et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, when a lot of data are available, a subset can be devoted to validation in order to independently evaluate model performances (Saint-André et al 2005;Wutzler et al 2008;Genet et al 2011). The use of covariate models is another way to improve the validity range of biomass equations; this approach consists in fitting biomass equations site by site (or stand by stand) and to relate equation parameters to site/stand variables (Saint- André et al 2005;António et al 2007;Genet et al 2011). Finally, the problem of tree component additivity is now commonly solved by using joint-generalized least square regression, also called seemingly unrelated regression (Parresol 2001;Lambert et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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Improving the robustness of biomass functions: from empirical to functional approaches

Hounzandji

Jonard

Nys

et al. 2014

Annals of Forest Science

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Abstract& Key message We developed precise, consistent, generic, and robust biomass equations for seven aboveground tree components of sessile and pedunculate oaks. These equations can be used to accurately estimate carbon stocks and fluxes in and out of the forest. & Context Large uncertainties still persist when using existing biomass equations for larger scale applications. & Aims The objective of this study was to test two contrasting modeling approaches to obtain biomass estimates of various components (stem, stem wood, stem bark, crown, and three branch categories) for Quercus petraea and Quercus robur and to compare them in terms of predictive capacity, genericity, consistency, and robustness. & Methods All models were calibrated on a total of 117 oak trees sampled over a wide range of sites and stands and further tested on an independent data set of 33 trees. The "empirical" approach consisted in declining a common allometric equation based on two variables (diameter at breast height and total height) into all its possible forms and selecting the final model on purely statistical performances; the "structural" method was based on the fitting of a priori dedicated model forms for each component to allow a clear interpretation of the model parameters. & Results For the stem components, both approaches resulted in similar statistical performances despite difference in model forms and number of parameters. Although equally performant on the validation data set for the total crown, only the structural model gave satisfactory results when applied to the independent data set. Both approaches failed to accurately predict the branch fractions on the validation data set. & Conclusion Using physically based model forms increased the robustness of the biomass equations.

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Methodology for Regional to Global Mapping of Aboveground Forest Biomass

Rodríguez-Veiga

Saatchi

Wheeler

et al. 2017

Earth Observation for Land and Emergency Monitoring

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Age-related equations for above- and below-ground biomass of a Eucalyptus hybrid in Congo

Cited by 165 publications

References 19 publications

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

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

Improving the robustness of biomass functions: from empirical to functional approaches

Methodology for Regional to Global Mapping of Aboveground Forest Biomass

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