Estimating density and biomass of oil palm trunks

Henson, Ian E. and Mohd Haniff Harun and Mazli Eswa and Mohd Tayeb Dolmat (2003) Estimating density and biomass of oil palm trunks. [Proceedings Paper]

Present methods for estimating dry matter partitioning to the trunk depend on a linear regression relating mean trunk tissue density to palm age and on an assumption that the trunk can be represented by a cylinder of constant diameter. The regression equation was established over 30 years ago and its validity for current planting materials and conditions has not, as far as we are aware, been subsequently verified. Using a special drill bit designed for use with hardwood trees, trunk tissue core samples of precise diameter and length were taken at three heights from 'smooth trunk' palms (i.e. palms from which frond bases had detached) in an experiment with initial planting densities of 120, 160 and 200 palms per hectare. The absence of old frond bases on the sampled palms considerably facilitated sampling as the boundary between frond base and trunk is often difficult to determine and the need to manually remove bases can injure the palm. The assumption of constant diameter with height was examined by measuring the diameter at the three heights. Trunk height increased with planting density as observed generally, while frond emission and mean trunk diameter decreased. Both these responses are characteristic of etiolation, and gave rise to longer internodes at increased planting density. As noted by other workers, trunk tissue density decreased both with trunk height and with distance from the trunk periphery. Trunk diameter decreased significantly with height at all palm spacings. Mean trunk tissue density did not differ significantly at the two lowest planting densities but was increased at the highest planting density, such that palm spacing effect on trunk density was highly significant. Because of this, the hypothesis that total trunk biomass might not differ with planting density as a consequence of a decrease in mean tissue density with increased palm density, was not supported. Trunk biomass estimates per palm obtained by the conventional method were found to be lower than measured ones by 9.5, 4. 3 and 17. 5 per cent for the low, medium and high planting densities, respectively. A similar result was obtained when published data for felled palms were analysed.

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Abstract

Present methods for estimating dry matter partitioning to the trunk depend on a linear regression relating mean trunk tissue density to palm age and on an assumption that the trunk can be represented by a cylinder of constant diameter. The regression equation was established over 30 years ago and its validity for current planting materials and conditions has not, as far as we are aware, been subsequently verified. Using a special drill bit designed for use with hardwood trees, trunk tissue core samples of precise diameter and length were taken at three heights from 'smooth trunk' palms (i.e. palms from which frond bases had detached) in an experiment with initial planting densities of 120, 160 and 200 palms per hectare. The absence of old frond bases on the sampled palms considerably facilitated sampling as the boundary between frond base and trunk is often difficult to determine and the need to manually remove bases can injure the palm. The assumption of constant diameter with height was examined by measuring the diameter at the three heights. Trunk height increased with planting density as observed generally, while frond emission and mean trunk diameter decreased. Both these responses are characteristic of etiolation, and gave rise to longer internodes at increased planting density. As noted by other workers, trunk tissue density decreased both with trunk height and with distance from the trunk periphery. Trunk diameter decreased significantly with height at all palm spacings. Mean trunk tissue density did not differ significantly at the two lowest planting densities but was increased at the highest planting density, such that palm spacing effect on trunk density was highly significant. Because of this, the hypothesis that total trunk biomass might not differ with planting density as a consequence of a decrease in mean tissue density with increased palm density, was not supported. Trunk biomass estimates per palm obtained by the conventional method were found to be lower than measured ones by 9.5, 4. 3 and 17. 5 per cent for the low, medium and high planting densities, respectively. A similar result was obtained when published data for felled palms were analysed.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. TP684 P3I61 2003 Call Number
AGROVOC Term:	oil palm > oil palm Prefer using Elaeis guineensisElaeis guineensis
AGROVOC Term:	biomass
AGROVOC Term:	sampling
AGROVOC Term:	data analysis
AGROVOC Term:	trunks
AGROVOC Term:	foresters
AGROVOC Term:	carbon stock assessments
Geographical Term:	Malaysia
Depositing User:	Nor Hasnita Abdul Samat
Date Deposited:	04 Aug 2024 08:30
Last Modified:	04 Aug 2024 08:30
URI:	http://webagris.upm.edu.my/id/eprint/871

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