Investigating tree stand parameter for rubber tree aboveground biomass and carbon stock estimation

Iqbal Putut Ash Shidiq, Mohd Hasmadi Ismail, Mohammad Firuz Ramli, Norizah Kamarudin

Research output: Contribution to journalArticlepeer-review

Abstract

Rubber plantation becomes one of the most important economic crops, as well as an alternative solution for biomass resources. The IPCC reported that CO2 is one of the greenhouse gases causing global warming. It is important to reduce the carbon emission by optimizing the assessment of environmental effects from rubber plantation related to biomass and carbon dynamics. This study was conducted to estimate the above-ground biomass and carbon sequestration using two different allometric equations. It also analysed the relationship between the biomass and the two predictors, namely height and age group, using statistical model non-linear regression. The study area was in Felda Lubuk Merbau, Peninsular Malaysia, with a total of 8 sample plots, and 195 sample trees were measured for 30 x 30 meters in a rectangular shape. The plots were randomly distributed according to different tree age group 5, 10, 15 and 20 years old. The average estimated AGB of Dey et al. (1996) is 296.8 kg/tree, and Shorrocks et al. (1965) is 393.4 kg/tree, whereas the carbon sequestration is 148.43 kg/tree and 196.71 kg/tree from each equation, respectively. Between the two equations, the estimated AGB and carbon sequestration from the equation of Shorrocks et al. (1965) gave a higher value. The statistical tests using non-linear regression showed the model two predictors having quite a robust relationship in determining the value of aboveground biomass. The variable height that was regressed with two different nonlinear models (power and exponential regression) indicates quite high R2 value (>0.73 and >0.63) and a significant level (<0.005). It also revealed similar results for the model of the variable age group that regressed with two similar models (R2 = >0.75 and >0.65). All models gave robust R2 value, which indicated that the variance of the dataset is properly explaining the relationship of the variables. The amount of AGB is peaked when reaching the age of 10 (ten) as it follows the optimum physical growth of height within this age group. Even though the age group is not included in previous general biomass allometric equations, it affected the cycle of biomass estimation. It relates to the physical growth and the development of rubber tree structures such as trunk diameter and tree canopy that became the factors contributing to the changes for both estimated AGB and carbon sequestration.

Original languageEnglish
Pages (from-to)435-452
Number of pages18
JournalMalaysian Forester
Volume83
Issue number2
Publication statusPublished - 2020

Keywords

  • Aboveground biomass
  • Allometric equations
  • Rubber plantation
  • Statistical model
  • Tree stand parameter

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