Studi Mutu Kayu Jati di Hutan Rakyat Gunungkidul III. Sifat Fisika Kayu

Abstract

Penelitian ini bertujuan untuk mengetahui variasi sifat fisika kayu dari pohon jati yang tumbuh di 3 tempat berbeda (Panggang, Playen, Nglipar) hutan rakyat di kabupaten Gunungkidul. Parameter yang diukur adalah kadar air segar (KAS), kerapatan dasar (KD), dan penyusutan linier maupun volumetrik. Sebanyak 3 pohon di tiap lokasi ditebang kemudian tiap pohon dibagi menjadi 3 potongan di posisi aksial yaitu pangkal, tengah, dan ujung. Tiap potongan tersebut kemudian dibagi 3 dalam posisi radial yaitu dekat hati, tengah, dan dekat kulit. Kisaran nilai KD dan KAS adalah 504-672 kg/cm3 dan 47-125%, secara berturutan. Hasil analisis keragaman menunjukkan sampel Playen bagian ujung cenderung memberikan nilai rerata KD lebih tinggi demikian juga bagian dekat kulit pada arah radial. Sampel Nglipar memberikan nilai kisaran KAS paling rendah (47-70%) sedangkan pada posisi radial nilai rerata tertinggi diamati di dekat hati (100,51%). Kisaran nilai penyusutan longitudinal, radial, dan tangensial adalah 0,39-0,88%; 2,75-3,93%; dan 4,30-6,68%, secara berturutan. Hasil analisis keragaman menunjukkan pengaruh faktor tempat tumbuh dimana sampel Nglipar memberikan nilai penyusutan longitudinal dan tangensial terendah. Nilai penyusutan total dalam kisaran 5,26-15,07%, sedangkan perbandingan penyusutan tangensial dan radial (rasio T/R) antara 1,38-2,13. Secara umum, kerapatan dasar yang diukur mempunyai nilai yang tidak jauh dengan nilai dari beberapa penelitian terhadap jati konvensional serta lebih tinggi dari beberapa jati unggul dari kultur jaringan pohon umur muda. Perlu diperhatikan adalah tingginya penyusutan dan ketidakstabilan dimensi yang diukur di beberapa sampel dalam eksperimen ini.Kata kunci: Tectona grandis, sifat fisika, kerapatan dasar, hutan rakyat, GunungkidulA study of teak wood quality from community forests in Gunungkidul III. Physical propertiesAbstractThe objective of this work is to explore the variation of physical properties of wood from teak trees grown in 3 different sites (Panggang, Playen, Nglipar) from community forests of Gunungkidul Regency. The measured parameters were green moisture content (GMC), basic density (BD), and linear as well as volumetric shrinkage. The three trees were collected at each site then were divided into three axial parts i.e. base, center, and top of the trees. Further, each axial part was divided into 3 radial positions i.e. near pith, middle, and near bark. The range of BD and GMC values were 504-672 kg/cm3 and 47-125%, consecutively. The result of analysis of variance showed that samples of Playen at the top parts tended to give higher average values of all physical properties measured as well as the samples at near bark of radial position. Samples from Nglipar exhibited the lowest range of GMC values (47-70%) whereas the highest values in the radial direction were observed in the near pith samples (100.51%). The range values of longitudinal, radial and tangential shrinkage were 0.39-0.88%; 2.75-3.93%; and 4.30-6.68%, respectively. By analysis of variance, site factor significantly affected of which samples of Nglipar showed the lowest levels of longitudinal and tangential shrinkage. The total shrinkage values were 5.26-15.07% as the T/R ratio were 1.38-2.13. In general, the BD levels of teak from Gunungkidul were comparable to those reported for conventional for teaks plantation and higher than those of young tissues cultural teaks. However, attention should be taken as the high magnitude of shrinkage as well as dimensional stability showed by several samples in this experiment.