Treffer: FORM FACTORS AND VOLUME MODELS FOR ESTIMATING TREE BOLE VOLUME OF MAHOGANY AT COMMUNITY FORESTS IN CENTRAL JAVA.

Form factors and volume models are often be used in the estimation of tree volumes. However, a few studies have developed and evaluated the accuracy of form factors and volume models for estimating tree volumes of community forests. This study aimed to formulate form factors and volume models and assess their prediction accuracy for estimating tree bole volumes of mahogany at community forests in Central Java. This study used 120 sample trees with diameters of 6-38 cm to formulate artificial and absolute form factors and to develop tree bole volume models. These form factors coupled with bole height and total height were used in simple volume equations. Regression analyses were used to develop volume models using the diameter and total height as predictors. The simple volume equations and volume models' prediction accuracy was evaluated using a cross-validation dataset and independent dataset (30 sample trees). The artificial form factor (0.68 ± 0.11) of mahogany, which was higher than the absolute form factor (0.46 ± 0.09), provided accurate estimates of tree bole volumes when it was used with the bole height instead of the total height. The volume model that uses diameter and total height produced the most accurate estimates, while the volume model that uses diameter alone provided the most practical yet reliable tool for estimating tree bole volumes of mahogany. The results of this study are useful for improving community forest management. [ABSTRACT FROM AUTHOR]

Faktor bentuk dan model volume sering digunakan untuk pendugaan volume pohon. Akan tetapi, masih sedikit penelitian yang mengembangkan dan mengevaluasi akurasi faktor bentuk dan model volume untuk pendugaan volume pohon di hutan rakyat. Penelitian ini bertujuan memformulasikan faktor bentuk dan model volume serta menilai akurasinya untuk menduga volume batang pohon mahoni pada hutan rakyat di Jawa Tengah. Penelitian ini menggunakan 120 pohon contoh berdiameter 6-38 cm, untuk memformulasikan faktor bentuk buatan dan faktor bentuk absolut serta menyusun model-model volume batang pohon. Faktor-faktor bentuk beserta tinggi pangkal tajuk dan tinggi total digunakan dalam persamaan volume sederhana. Analisis regresi digunakan untuk menyusun model-model volume menggunakan diameter dan tinggi total sebagai peubah penduga. Akurasi pendugaan dari persamaan volume sederhana dan model-model volume dievaluasi menggunakan data validasi silang dan data terpisah (30 pohon contoh). Faktor bentuk buatan pohon mahoni (0,68 ± 0,11), yang lebih tinggi daripada faktor bentuk absolut (0,46 ± 0,09), memberikan nilai-nilai dugaan volume pohon yang akurat jika digunakan bersama tinggi pangkal tajuk daripada tinggi total. Model-model volume yang menggunakan diameter dan tinggi total menghasilkan nilai-nilai dugaan yang paling akurat, sedangkan model volume yang hanya menggunakan diameter paling praktis namun dapat diandalkan untuk pendugaan volume batang pohon mahoni. Hasil penelitian bermanfaat untuk perbaikan pengelolaan hutan rakyat. [ABSTRACT FROM AUTHOR]

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