Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland
Spotted gum (<i>Corymbia citriodora</i> spp. <i>variegata</i>; CCV) has been widely planted, has a wide natural distribution, and is the most important commercially harvested hardwood species in Queensland, Australia. It has a great capacity to sequester carbon, thus reducing...
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MDPI AG
2021-09-01
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| Online Access: | https://www.mdpi.com/1999-4907/12/9/1210 |
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| author | Trinh Huynh Grahame Applegate Tom Lewis Anibal Nahuel A. Pachas Mark A. Hunt Mila Bristow David J. Lee |
| author_facet | Trinh Huynh Grahame Applegate Tom Lewis Anibal Nahuel A. Pachas Mark A. Hunt Mila Bristow David J. Lee |
| author_sort | Trinh Huynh |
| collection | DOAJ |
| description | Spotted gum (<i>Corymbia citriodora</i> spp. <i>variegata</i>; CCV) has been widely planted, has a wide natural distribution, and is the most important commercially harvested hardwood species in Queensland, Australia. It has a great capacity to sequester carbon, thus reducing the impact of CO<sub>2</sub> emissions on climate. Belowground root biomass (BGB) plays an important role as a carbon sink in terrestrial ecosystems. To explore the potential of biomass and carbon accumulation belowground, we developed and validated models for CCV plantations in Queensland. The roots of twenty-three individual trees (size range 11.8–42.0 cm diameter at breast height) from three sites were excavated to a 1-m depth and were weighed to obtain BGB. Weighted nonlinear regression models were most reliable for estimating BGB. To evaluate the candidate models, the data set was cross-validated with 70% of the data used for training and 30% of the data used for testing. The cross-validation process was repeated 23 times and the validation of the models were averaged over 23 iterations. The best model for predicting spotted gum BGB was based on a single parameter, with the diameter at breast height (D) as an independent variable. The best equation BGB = 0.02933 × D<sup>2.5805</sup> had an adjusted R<sup>2</sup> of 0.854 and a mean absolute percentage error of 0.090%. This equation was tested against published BGB equations; the findings from this are discussed. Our equation is recommended to allow improved estimates of BGB for this species. |
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| language | English |
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| publishDate | 2021-09-01 |
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| series | Forests |
| spelling | doaj.art-d9a3bda1aabd41cba7f37cb06906f72d2023-11-22T13:07:43ZengMDPI AGForests1999-49072021-09-01129121010.3390/f12091210Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in QueenslandTrinh Huynh0Grahame Applegate1Tom Lewis2Anibal Nahuel A. Pachas3Mark A. Hunt4Mila Bristow5David J. Lee6Forest Research Institute, University of the Sunshine Coast, Maroochydore, QLD 4556, AustraliaForest Research Institute, University of the Sunshine Coast, Maroochydore, QLD 4556, AustraliaForest Research Institute, University of the Sunshine Coast, Maroochydore, QLD 4556, AustraliaForest Research Institute, University of the Sunshine Coast, Maroochydore, QLD 4556, AustraliaUniversity of Tasmania, Churchill Ave, Hobart, TAS 7001, AustraliaPlant Health Australia, Canberra, ACT 2600, AustraliaForest Research Institute, University of the Sunshine Coast, Maroochydore, QLD 4556, AustraliaSpotted gum (<i>Corymbia citriodora</i> spp. <i>variegata</i>; CCV) has been widely planted, has a wide natural distribution, and is the most important commercially harvested hardwood species in Queensland, Australia. It has a great capacity to sequester carbon, thus reducing the impact of CO<sub>2</sub> emissions on climate. Belowground root biomass (BGB) plays an important role as a carbon sink in terrestrial ecosystems. To explore the potential of biomass and carbon accumulation belowground, we developed and validated models for CCV plantations in Queensland. The roots of twenty-three individual trees (size range 11.8–42.0 cm diameter at breast height) from three sites were excavated to a 1-m depth and were weighed to obtain BGB. Weighted nonlinear regression models were most reliable for estimating BGB. To evaluate the candidate models, the data set was cross-validated with 70% of the data used for training and 30% of the data used for testing. The cross-validation process was repeated 23 times and the validation of the models were averaged over 23 iterations. The best model for predicting spotted gum BGB was based on a single parameter, with the diameter at breast height (D) as an independent variable. The best equation BGB = 0.02933 × D<sup>2.5805</sup> had an adjusted R<sup>2</sup> of 0.854 and a mean absolute percentage error of 0.090%. This equation was tested against published BGB equations; the findings from this are discussed. Our equation is recommended to allow improved estimates of BGB for this species.https://www.mdpi.com/1999-4907/12/9/1210allometric equationbelowground root biomasscross-validationspotted gum plantationsweighted nonlinear models |
| spellingShingle | Trinh Huynh Grahame Applegate Tom Lewis Anibal Nahuel A. Pachas Mark A. Hunt Mila Bristow David J. Lee Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland Forests allometric equation belowground root biomass cross-validation spotted gum plantations weighted nonlinear models |
| title | Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland |
| title_full | Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland |
| title_fullStr | Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland |
| title_full_unstemmed | Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland |
| title_short | Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (<i>Corymbia citriodora</i> subspecies <i>variegata</i>) in Queensland |
| title_sort | species specific allometric equations for predicting belowground root biomass in plantations case study of spotted gums i corymbia citriodora i subspecies i variegata i in queensland |
| topic | allometric equation belowground root biomass cross-validation spotted gum plantations weighted nonlinear models |
| url | https://www.mdpi.com/1999-4907/12/9/1210 |
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