Estimasi Volume Batang Bebas Cabang dan Biomassa Genus Shorea di Hutan Tropis Basah PT Sari Bumi Kusuma Kalimantan Tengah

Yanuar Tri Wardono, Ris Hadi Purwanto

2012 | Skripsi | S1 KEHUTANAN

Hutan tropis yang dikelola oleh PT Sari Bumi Kusuma memegang peranan penting dalam menstabilkan iklim global. Disisi lain, pemanfaatan hutan untuk produksi kayu dapat mengakibatkan berkurangnya stok karbon dalam biomassa tegakan. Penelitian ini bertujuan untuk menyusun persamaan allometrik pendugaan volume batang pohon, persentase biomassa berbagai komponen pohon, mengetahui potensi volume batang bebas cabang dan biomassa pohon terutama dari genus shorea di areal hutan bekas tebangan (logged overa area, LOA), baik yang dikelola dengan sistem silvikultur Tebang Pilih Tanam Jalur (TPTJ) maupun tanpa perlakukan (non TPTJ) di hutan tropis PT Sari Bumi Kusuma. Metode pengukuran volume dan biomassa pohon dilakukan dengan cara penebangan (destuctive sampling). Pengukuran volume batang diawali dengan penebangan pohon, selanjutnya dipotong menjadi beberapa segmen, dan diukur volume batangnya untuk tiaptiap segmen. Pengukuran biomassa dilakukan dengan penimbangan berat basah total untuk tiap-tiap organ tanaman (batang, cabang, daun, akar). Pengambilan sampel dari berat basahnya dilakukan di lapangan selanjutnya dikeringkan dengan oven sampai mencapai berat konstan (biomassa). Hasil penelitian ini menunjukkan bahwa persamaan allometrik yang menyatakan hubungan antara volume batang bebas cabang (Vk) dengan biomassanya (Wk) adalah sebagai berikut: Wk = 273,021(Vk)0,998 ; R2 = 0,954, genus shorea, TPTJ Wk = 527,527(Vk)1,009 ; R2 = 0,963, genus campuran, TPTJ Wk = 626,245(Vk)0,900 ; R2 = 0,965, genus shorea, non TPTJ Wk = 527,527(Vk)1,009 ; R2 = 0,963, genus campuran, non TPTJ Berdasarkan persamaan allometrik yang diperoleh, selanjutnya digunakan untuk menghitung potensi volume batang bebas cabang dan biomasaanya dari data hasil inventarisasi 6 buah Petak Ukur Permanen (PUP) yang luasnya masing-masing 1 hektar. Hasil penghitungan potensi volume batang bebas cabang (Vk) dan biomassanya (Wk) adalah sebagai berikut: Vk = 68,324 m3/ha (50,02%) ; genus shorea, TPTJ Vk = 136,607 m3/ha ; genus campuran, TPTJ Vk = 72,028 m3/ha (36,08%) ; genus shorea, non TPTJ Vk = 199,612 m3/ha ; genus campuran, non TPTJ Wk = 18,583 ton/ha (25,74%) ; genus shorea, TPTJ Wk = 72,183 ton/ha ; genus campuran, TPTJ Wk = 39,093 ton/ha (36,98%) ; genus shorea, non TPTJ Wk = 105,712 ton/ha ; genus campuran, non TPTJ Hasil penelitian juga menunjukkan bahwa potensi biomassa yang sementara ini tidak dimanfaatkan oleh perusahaan (akar, cabang, daun dan ujung batang non bebas cabang) berkisar 60% dari total biomassa pohon untuk areal TPTJ dan berkisar 40% dari total biomassa pohon untuk areal non TPTJ.

Tropical forest which managed by PT Sari Bumi Kusuma occupied an important part to stabillized global climate. Otherwise, forest utilization for wood production can causes decreasing of carbon stock in stands’ biomass. This research aim to arranged Allometric equation of stem volume estimation, biomass precentage of tree components, figure out the potency of free branch’s stem volume and tree’s biomass especially from genus of Shorea in Logged Over Area (LOA), whether managed by strip clearing and replanting silvicultural system (known as TPTJ) or without treatment (non strip clearing and replanting) in tropical forest of PT Sari Bumi Kusuma. The measurement method of Tree’s volume and biomass was conducted by destructive sampling. Stem’s volume measurement started with trees’ logging, then cutted become several segments, and measuring the stem’s volume for each segments. Biomass measurement was conducted by total wet weight scaling for each plant organs (stem, branch, leave, root). Wet weight’s sampling conducted on the field, further drained by an oven until reached the constant weight (biomass). Result of this research shown that allometric equation which indicated relation between branch-free stem’s volume (Vk) with the biomass (Wk) are as the following analysis: Wk = 273,021(Vk)0,998 ; R2 = 0,954, genus of shorea, TPTJ Wk = 527,527(Vk)1,009 ; R2 = 0,963, mixed genus, TPTJ Wk = 626,245(Vk)0,900 ; R2 = 0,965, genus of shorea, non TPTJ Based on the result of allometric equation, then have been used for calculated potency of branch-free stem’s volume and these biomass from 6 permanent plots measurement inventore result data, which extent of 1 hectare for each plot. Result of branch-free stem’s volume potency (Vk) and these biomass (Wk) are as the following analysis: Vk = 68,324 m3/ha (50,02%) ; genus of shorea, TPTJ Vk = 136,607 m3/ha ; mixed genus, TPTJ Vk = 72,028 m3/ha (36,08%) ; genus of shorea, non TPTJ Vk = 199,612 m3/ha ; mixed genus, non TPTJ Wk = 18,583 ton/ha (25,74%) ; genus of shorea, TPTJ Wk = 72,183 ton/ha ; mixed genus, TPTJ Wk = 39,093 ton/ha (36,98%) ; genus of shorea, non TPTJ Wk = 105,712 ton/ha ; mixed genus, non TPTJ Result of the research also shown that biomass potency that not in used temporary by the company (root, branch, leave and tip of non branch-free stem) is arround 60% from total of tree biomass for strip clearing and replanting area and revolved 40% from total of tree’s biomass for non strip clearing and replanting area

Kata Kunci : volume batang bebas cabang, biomassa, allometrik, TPTJ, LOA