Ellipse or superellipse for tree-ring geometries? evidence from six conifer species
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| Title: | Ellipse or superellipse for tree-ring geometries? evidence from six conifer species |
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| Authors: | Weiwei Huang, Kehang Ma, Daniel K. Gladish |
| Source: | Trees. 38:1403-1413 |
| Publisher Information: | Springer Science and Business Media LLC, 2024. |
| Publication Year: | 2024 |
| Subject Terms: | Superellipse, Bilateral symmetry, Tree-ring area, Tree-ring geometry |
| Description: | Key message: Tree-ring shapes of the six studied coniferous species tend to be bilaterally symmetrical, and the superellipse equation is sufficient to describe the tree-ring boundaries and estimate the basal area increment. Abstract: In nature, under environmental pressures, such as wind, slope, water availability, etc., tree-ring shapes in most cases appear to be elliptical rather than circular. Compared with the ellipse equation, the superellipse equation includes an additional parameter that allows the generation of a larger range of geometries: hypoellipse, ellipse, and hyperellipse. The more complex Gielis equation can generate asymmetrical shapes. In the present study, we modeled the geometries of tree-rings for six coniferous species using the superellipse equation (i.e., the three-parameter model) and the more complex Gielis equation (i.e., the five-parameter model). The species-specific mean value of n approached 2 and the k-value was lower than 1, which confirmed that most tree-ring shapes of the studied coniferous species were closer to an ellipse rather than a circle. However, based on superellipse equation the n-value and k-value both showed an inter-annual fluctuation that ranged between 1.75–2.25 and 0.82–1.00, respectively. This suggests that most samples of tree-rings did not follow the typical ellipse equation, but the superellipse equation. Although the Gielis equation is slightly better in the goodness of fit than the superellipse equation, 86.67% of the percent errors (PEs) of RMSE adj between these two equations were smaller than 5%, which means that the superellipse equation is better given the trade-off between the model structural complexity and goodness of fit. Most tree-ring shapes tend to be bilaterally symmetrical, and the three-parameter superellipse equation was verified to fit the tree-ring boundaries and estimate the inter-annual increments of tree-ring area well. |
| Document Type: | Article |
| Language: | English |
| ISSN: | 1432-2285 0931-1890 |
| DOI: | 10.1007/s00468-024-02561-2 |
| Rights: | Springer Nature TDM |
| Accession Number: | edsair.doi.dedup.....f94503ac82ac7d0e7e65339d594b5adc |
| Database: | OpenAIRE |
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Nájsť tento článok vo Web of Science | Abstract: | Key message: Tree-ring shapes of the six studied coniferous species tend to be bilaterally symmetrical, and the superellipse equation is sufficient to describe the tree-ring boundaries and estimate the basal area increment. Abstract: In nature, under environmental pressures, such as wind, slope, water availability, etc., tree-ring shapes in most cases appear to be elliptical rather than circular. Compared with the ellipse equation, the superellipse equation includes an additional parameter that allows the generation of a larger range of geometries: hypoellipse, ellipse, and hyperellipse. The more complex Gielis equation can generate asymmetrical shapes. In the present study, we modeled the geometries of tree-rings for six coniferous species using the superellipse equation (i.e., the three-parameter model) and the more complex Gielis equation (i.e., the five-parameter model). The species-specific mean value of n approached 2 and the k-value was lower than 1, which confirmed that most tree-ring shapes of the studied coniferous species were closer to an ellipse rather than a circle. However, based on superellipse equation the n-value and k-value both showed an inter-annual fluctuation that ranged between 1.75–2.25 and 0.82–1.00, respectively. This suggests that most samples of tree-rings did not follow the typical ellipse equation, but the superellipse equation. Although the Gielis equation is slightly better in the goodness of fit than the superellipse equation, 86.67% of the percent errors (PEs) of RMSE adj between these two equations were smaller than 5%, which means that the superellipse equation is better given the trade-off between the model structural complexity and goodness of fit. Most tree-ring shapes tend to be bilaterally symmetrical, and the three-parameter superellipse equation was verified to fit the tree-ring boundaries and estimate the inter-annual increments of tree-ring area well. |
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| ISSN: | 14322285 09311890 |
| DOI: | 10.1007/s00468-024-02561-2 |