Growth and Yield Models for Eucalyptus Species using Geospatial Technology in Aek Nauli, North Sumatra Province, Indonesia
Villanueva, Teodoro R.
Carandang, Myrna G.
Bantayan, Nathaniel C
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This study was conducted primarily to develop a yield prediction model for forest plantation of Eucalyptus spp in Aek Nauli, North Sumatra, Indonesia as a contribution toward sustainable forestry development and management. Specifically, it aimed to : develop growth and yield models for Eucalyptus plantations, test the models to identify the best growing species, integrate growth and yield models into a GIS model and recommend appropriate management strategies to improve growth and yield. The data in this study came from 650 rhombic plots consisting of 106 PSPs and 544 inventory plots. Six candidate non- linear regression equations using original ages and initial and projection ages were tested and assessed for statistical validity and accuracy in predicting yield. Models using initial age, specifically, model 2 was found consistently to be the best model in almost Eucalyptus plantations. Among the models using initial and projection age, model 4 was the best model. Model 2 using original ages is better than model 4 using initial and projection age because model using original ages is more reliable and it had the growth curve follows a sigmoid shape. There is significant difference between models among Eucalyptus species to predict the merchantable volume. Consequently, each Eucalyptus species has a specific model to predict the yield. Results show that E. hybrid has the highest (230 m3/ha) of averages predicted volume in year 7 and E. pellita has the lowest (104 m3/ha) of averages predicted volume in year 7. The most important factors affecting yield of the , E. urophylla, and all species are rainfall while for E. grandis, E. pellita and mixed Eucalyptus are stand density, elevation, interaction site index and age, respectively Environmental requirements for viable plantations of various Eucalyptus species are site index ranges from 15 to 25 m, stand density ranges from 800 to 1200 tree/ha, spacing ranges from 6 to 9 m2, plot size ranges from 0.025 to 0.04 ha, depth of top soil ranges from 20 to 40 cm, rainfall ranges from 100 to 400 mm/month, slope ranges from 0 to 45 %, elevation ranges from 600 to 1700 masl, and groups of soil are A, C and E.