Model Penduga Distribusi Diameter Hutan Tanaman Jati (Tectona grandis L.F.)

Darmawan Budiantho, Dr.Ir. Agus Setyarso

1993 | Tesis | S2 Ilmu Kehuatanan

Struktur tegakan hutan Jati dapat digambarkan oleh distribusidiameternya. Distribusi diameter diduga dapat diwakili modelmatematik fungsi Beta, yang parameter-parameternya dapat ditaksirmelalui model atau persamaan regresi berdasarkan hubungan antaraDiameter maksimum, minimum, rata-rata dan varian dengan peubahbebas umur (U), indek tempat tumbuh (S) dan kerapatantegakan/jumlah pohon (N) atau jarak rata-rata antar pohon dalamluasan per hektar (Sm). Data penelitian berupa data hasil pengukuran diameter setinggidada (Dbh) di dalam petak coba (pc) hutan tanaman jatipada berbagai kombinasi umur dan bonita yang dikelompokkan kedalamkelas-kelas diameter dengan lebar kelas 2 s/d 5 cm. Kemampuanparameter-parameter fungsi Beta dalam menampung berbagai bentukdistribusi diameter ditentukan oleh uji statistik KolmogorovSmirnov.Hasil penelitian menunjukkan bahwa distribusi diametertegakan hutan jati dapat ditampung dengan baik oleh parameterparameterfungsi Beta. Persamaan regresi yang dihasilkan yaituOmak, Dmin, Ort dan Var.D secara bersama-sama kurang mampu untukmenaksir distribusi diameter empiriknya namun demikian, persamaan Dmin dan Ort relatif cukup akurat.

The structure of Teak stands can be effectively described by their diameter distributions.Mathematical distribution function, i.e, Beta function, is proposed to depict the the diameter distribution. While Beta parameters are to be determined from several variables, namely Maximum Diameter (D), Minimum D, Mean D and Variance D, their dynamics shall be estimated by other stand characteristics such as age (U), site index (S), stand density or number of trees per hectar (N) or average distance of trees in forest area per hectar (Sm). The data used in this study were taken from measurements .in sample plots of various combinations of age and site. The data were tabulated in diameter class with interval of 2 cm up to 5 cm. The capability of the predicted Beta functions in illustrating the actual diameter distributions were tested by Kolmogorov - Smirnov technique. The result of study proved that the diameter distribution of teak stand can sufficiently be presented by Beta function. The proposed regression equations on the necessery varia bles (Max.D, Min.D, Mean D and Var.D) turned out not to be significant. However, it can be noted that equation on Min.D and Mean D were considered sufficient.

Kata Kunci : Pertumbuhan Tanaman Jati,Struktur Tegakan Pohon,Ilmu Kehutanan