GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA
The aim of this study was to develop a generalized height-diameter model for predicting tree height of Acacia mangium plantations in South Sumatra that could account for the variability of site and stand conditions. Six commonly used non-linear growth functions (i.e. Gompertz, Chapman-Richards, Lund...
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| Format: | Article |
| Language: | English |
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Ministry of Environment and Forestry
2010-06-01
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| Series: | Indonesian Journal of Forestry Research |
| Subjects: | |
| Online Access: | http://ejournal.forda-mof.org/ejournal-litbang/index.php/IJFR/article/view/62 |
| _version_ | 1811279515742109696 |
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| author | Haruni Krisnawati Yue Wang Peter K. Ades |
| author_facet | Haruni Krisnawati Yue Wang Peter K. Ades |
| author_sort | Haruni Krisnawati |
| collection | DOAJ |
| description | The aim of this study was to develop a generalized height-diameter model for predicting tree height of Acacia mangium plantations in South Sumatra that could account for the variability of site and stand conditions. Six commonly used non-linear growth functions (i.e. Gompertz, Chapman-Richards, Lundqvist-Korf, Weibull, modified logistic, and exponential) were selected as candidate base models and were fitted to individual tree’s height-diameter data of A.mangium plantations. A total of 13,302 trees collected from permanent sample plots with various spacing , stand age, and site quality were available for this study. The data were split into two sets: one set being the majority (75%) was used to estimate model parameters and the remaining data set (25%) was used to validate the models. The results showed that the six base models produced almost identical fits with a relatively high root mean squared error (± 3.4 m) and a relatively low proportion of the total variation in obser ved tree height (52.5 - 53.4%). The Lundqvist-Korf (LK) model performed slightly better than the other models based on the goodness of fit as well as bias and standard errors of the predictions. This LK model can be fitted easily and provided more satisfactory fit when additional variables were included into the model, hence was selected as the base model. Introducing stand variables into the selected base model resulted in a significant improvement of the accuracy for predicting heights. The root mean squared error decreased by the value between 0.5564 and 1.4252 m and the proportion of variation explained by the model increased by the value between 13.88 and 33.21%. The best improvement based on fit and model validation was achieved by the generalized height-diameter model with inclusion of stand age and site index. |
| first_indexed | 2024-04-13T00:57:01Z |
| format | Article |
| id | doaj.art-f41fe02fe41c4d5f860b67958bddc287 |
| institution | Directory Open Access Journal |
| issn | 2355-7079 2406-8195 |
| language | English |
| last_indexed | 2024-04-13T00:57:01Z |
| publishDate | 2010-06-01 |
| publisher | Ministry of Environment and Forestry |
| record_format | Article |
| series | Indonesian Journal of Forestry Research |
| spelling | doaj.art-f41fe02fe41c4d5f860b67958bddc2872022-12-22T03:09:38ZengMinistry of Environment and ForestryIndonesian Journal of Forestry Research2355-70792406-81952010-06-017111910.20886/ijfr.2010.7.1.1-1965GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRAHaruni Krisnawati0Yue Wang1Peter K. Ades2Forest and Nature Conservation Research and Development CentreDepartment of Forest and Ecosystem Science, the University of MelbourneDepartment of Forest and Ecosystem Science, the University of MelbourneThe aim of this study was to develop a generalized height-diameter model for predicting tree height of Acacia mangium plantations in South Sumatra that could account for the variability of site and stand conditions. Six commonly used non-linear growth functions (i.e. Gompertz, Chapman-Richards, Lundqvist-Korf, Weibull, modified logistic, and exponential) were selected as candidate base models and were fitted to individual tree’s height-diameter data of A.mangium plantations. A total of 13,302 trees collected from permanent sample plots with various spacing , stand age, and site quality were available for this study. The data were split into two sets: one set being the majority (75%) was used to estimate model parameters and the remaining data set (25%) was used to validate the models. The results showed that the six base models produced almost identical fits with a relatively high root mean squared error (± 3.4 m) and a relatively low proportion of the total variation in obser ved tree height (52.5 - 53.4%). The Lundqvist-Korf (LK) model performed slightly better than the other models based on the goodness of fit as well as bias and standard errors of the predictions. This LK model can be fitted easily and provided more satisfactory fit when additional variables were included into the model, hence was selected as the base model. Introducing stand variables into the selected base model resulted in a significant improvement of the accuracy for predicting heights. The root mean squared error decreased by the value between 0.5564 and 1.4252 m and the proportion of variation explained by the model increased by the value between 13.88 and 33.21%. The best improvement based on fit and model validation was achieved by the generalized height-diameter model with inclusion of stand age and site index.http://ejournal.forda-mof.org/ejournal-litbang/index.php/IJFR/article/view/62Acacia mangium, generalized model, height-diameter relationship, non-linear growth function |
| spellingShingle | Haruni Krisnawati Yue Wang Peter K. Ades GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA Indonesian Journal of Forestry Research Acacia mangium, generalized model, height-diameter relationship, non-linear growth function |
| title | GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA |
| title_full | GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA |
| title_fullStr | GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA |
| title_full_unstemmed | GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA |
| title_short | GENERALIZED HEIGHT-DIAMETER MODELS FOR Acacia mangium Willd. PLANTATIONS IN SOUTH SUMATRA |
| title_sort | generalized height diameter models for acacia mangium willd plantations in south sumatra |
| topic | Acacia mangium, generalized model, height-diameter relationship, non-linear growth function |
| url | http://ejournal.forda-mof.org/ejournal-litbang/index.php/IJFR/article/view/62 |
| work_keys_str_mv | AT harunikrisnawati generalizedheightdiametermodelsforacaciamangiumwilldplantationsinsouthsumatra AT yuewang generalizedheightdiametermodelsforacaciamangiumwilldplantationsinsouthsumatra AT peterkades generalizedheightdiametermodelsforacaciamangiumwilldplantationsinsouthsumatra |