Analytical System Model of Growth Dynamic and Yield Regulation for Over-logged Swamp Forest in Riau

Aswandi[1] Abstract This study was aimed to build model of stand structure dynamic and yield regulation for logged-over uneven-aged swamp forest in Riau Province. Dynamic model of stand structure was developed based on a series data of permanent sampling plot and yield regulation method which was developed based on system analysis model approach. Logged-over natural forest in the concession area of PT. Diamond Raya Timber, Riau Province was selected for analysing the stand structure dynamic which consists of ingrowth, upgrowth and mortality functions. The model was constructed based on species group (Dipterocarpaceae, Non-Dipterocarpaceae and Non-Commercial). The result indicated that silviculture treatments (thinning and liberation) increased stand diameter. Average diameter increment in 3-10 years after timber cutting at permanent plot with silvicultural treatment was 0,43 cm/year and 0,37 cm/year wihout treatments. The result of simulation showed that cutting cycle 35 years decreased the Number of trees for cutting and unsustainable. The increasing of cutting cycle up to 40 years or the decrease diameter cutting limit to 40 cm was an alternative of yield regulation for sustainable yield management. Keywords : model, stand structure, logged-over forest, analytical system, yield regulation MODEL ANALISIS SISTEM DINAMIKA PERTUMBUHAN DAN PENGATURAN HASIL HUTAN RAWA BEKAS TEBANGAN DI RIAU Abstrak Penelitian ini bertujuan untuk membangun model analisis sistem dinamika struktur tegakan dan pengaturan hasil hutan rawa tidak seumur di Riau. Model disusun berdasarkan pada seri data petak ukur permanen di hutan alam bekas tebangan pada areal pengusahaan hutan PT. Diamond Raya Timber, Provinsi Riau. Dinamika struktur tegakan terdiri atas ingrowth, upgrowth, dan mortality. Model yang dibangun didasarkan pada kelompok jenis (Dipterocarpaceae, Non-Dipterocarpaceae dan Non-Komersial). Hasil simulasi menunjukkan bahwa dengan siklus tebang 35 tahun, tegakan pada siklus tebang kedua belum mencapai kondisi semula. Memperpanjang siklus tebang hingga 40 tahun atau menurunkan limit diameter hingga kelas diameter 40 merupakan alternatif untuk menjaga kelestarian hasil. Siklus tebang yang semakin panjang ini juga didukung oleh riap diameter yang lebih kecil dari 1 cm/tahun yang menjadi dasar penetapan siklus tebang 35 tahun. Kata kunci : model, struktur tegakan, hutan bekas tebangan, analisis sistem, pengaturan hasil [1] Staf Peneliti pada Balai Penelitian dan Pengembangan Kehutanan Sumatera di Pematangsiantar email : andiasw@yahoo.com