Model Pendugaan Isi Pohon Agathis...(Bambang E. Siswanto; Rinaldi I.) 485 MODEL PENDUGAAN ISI POHON Agathis loranthifolia Salisb DI KESATUAN PEMANGKUAN HUTAN KEDU SELATAN, JAWA TENGAH (Tree Volume Estimation Model of Agathis loranthifolia Salisb in Kedu Selatan Forest District, Central Java)*) s ABSTRACT The construction of tree volume table for Agathis loranthifolia Salisb was proposed to estimate the production of the species in the Forest District of Kedu Selatan, Central Java. In this study

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... two volume tables have been constructed based on 56 sample trees with the distribution of diameter at breast height of 30-67 cm and the distribution of tree height of crown base of 14-25 meter. Two volume tables were developed using formulas V = a.d b and V = a.d b .t c , where V = tree volume, d = diameter at breast height, t = tree height and a, b and c = constants. The results showed that based on the accuracy criteria used (standard error, mean and aggregative deviation), the resulted regression equations were acceptable for estimating tree volume with the standard errors of less than nine percent, mean deviation of less than six percent and aggregative deviation of less than 0.2%. ABSTRAK Penyusunan tabel isi pohon untuk Agathis loranthifolia Salisb dimaksudkan untuk menaksir hasil produksi jenis tersebut di wilayah Kesatuan Pemangkuan Hutan Kedu Selatan, Jawa Tengah. Tabel-tabel volume disusun berdasarkan 56 pohon model dengan sebaran diameter setinggi dada antara 30-67 cm dengan tinggi pangkal tajuk pohon antara 15-25 meter. Dua buah model persamaan regresi yang digunakan untuk menyusun tabel volume yaitu V = a.d b dan V = a.d b .t c di mana V = volume pohon tanpa kulit (sebagai peubah tak bebas); d = diameter pohon setinggi dada (sebagai peubah bebas); t = tinggi pohon (sebagai peubah bebas); a, b dan c = konstanta. Hasil penelitian menunjukkan bahwa berdasarkan kriteria keakuratan yang digunakan (galat baku, simpangan rata-rata, dan simpangan agregat), keempat persamaan regresi cukup memenuhi syarat ketelitian dengan galat baku < sembilan persen, simpangan rata-rata < enam persen dan simpangan agregatif < 0,2%, maka keempat persamaan regresi dipandang cukup memenuhi syarat ketelitian. Kata kunci: Model pendugaan, Agathis loranthifolia Salisb, isi pohon