Forecasting Economic Life of Rubber Plantation using Markov Model
2024
Uche, Uche Emmanuel
The economic life of a rubber plantation is fundamentally dependent on the tapped trees per hectare which is proximate of yield per hectare. The study determines the transition probability and the incremental utility of a plantation rubber tree population as it transits from the initial density of over 500 trees per hectare to an arbitrary uneconomical threshold of less than 200 trees per hectare that necessitates a replanting programme. It involves Markovian analysis of the evolution of rubber tree density through three definable Markov states- untapped, tapped and dead states. Six-year documentary data obtained from permanent experimental plots is used to carry out the stationary and 50-year cohort simulation of the transition probabilities of eight rubber clones through the three states. The fundamental matrix solution is computed for each clone to determine the mean passage time and time to absorption. The 50- year simulation of the rubber tree cohort using TreeAge Pro decision software, forecasts only three out of the eight clones to be above the 40% economic threshold tapped density after 30 years. These include IRCA 18 (58%), RRIC 100 (46%) and IRCA 109 (44%). Mean passage time in tapping averaged 35 years while mean passage time in untapped state is 7 years. The data is subjected to the nonparametric Chi square statistics to ascertain significance difference between clones in mean time to absorption, mean passage time and mean time to replanting. The result shows that significant difference exists between rubber clones in all these plantation economic indices. The Markov model therefore provides a convenient analytical framework for forecasting the dynamics of rubber tree density to determine the economic life of rubber plantation.
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