Allometric relationship and biomass partition of Kandelia obovata LIU & Yong planted in Nam Đinh province

Compared to regressions obtained using the traditional logarithmic transformation method, the above regressions had a much better fit. The original biomass data of the sample trees were also used to calculate the proportion of total biomass apportioned to trunk, branches, leaves and roots.
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Allometric relationship and biomass partition of Kandelia obovata LIU & Yong planted in Nam Đinh province JOURNAL OF SCIENCE OF HNUE Chemical and Biological Sci., 2013, Vol. 58, No. 9, pp. 91-103 This paper is available online at http://stdb.hnue.edu.vn ALLOMETRIC RELATIONSHIP AND BIOMASS PARTITION OF Kandelia obovata LIU & YONG PLANTED IN NAM DINH PROVINCE Pham Hong Tinh1 and Mai Sy Tuan2 1 Mangrove Ecosystem Research Center, Hanoi National University of Education 2 Faculty of Biology, Hanoi National University of Education Abstract. Measurements were made of 101 Kandelia obovata Liu & Yong trees growing in Giao Lac Commune, Giao Thuy District, Nam Dinh Province, and, based on the diameter (cm) at 30 cm above the widening of the trunk base, allometric regressions were done to estimate the biomass (kg) of the entire tree, above-ground biomass, trunk biomass, leaf biomass and below-ground biomass, found to be W = 0.10316D 1.85845 (R2 = 0, 86), W = 0.09012D 1.78752 (R2 = 0, 84), W = 0.04975D 1.94748 (R2 = 0, 79), W = 0.00899D 1.7643 (R2 = 0, 63) and W = 0.01420D 2.12146 (R2 = 0, 73), respectively. Compared to regressions obtained using the traditional logarithmic transformation method, the above regressions had a much better fit. The original biomass data of the sample trees were also used to calculate the proportion of total biomass apportioned to trunk, branches, leaves and roots. While for small trees (D ≤ 4 cm), 20% is leaves, 20% is branches, 35% is trunk and 25% is roots, for larger trees (D ≥ 10 cm), only about 5% is leaves, 5% is branches, 65% is trunk and 25% is roots. The allometric equations and biomass partition obtained in this study could be used effectively to account for biomass and carbon in Kandelia obovata Liu & Yong mangroves. Keywords: Allometric relationship, Kandelia obovata Liu & Yong, Biomass, Vietnam.1. Introduction Mangrove forest is an important ecosystem in tropical and subtropical coastalregions. However, this ecosystem is being degraded and damaged at an alarming rate byhuman activites, e.g. land use change, unsustainable exploitation and human populationincrease [6]. Moreover, the value of mangrove forests in terms of carbon accumulationand other factors are not well understood.Received September 26, 2013. Accepted December 18, 2013.Contact Pham Hong Tinh, e-mail address: phamtinhsp@yahoo.com 91 Pham Hong Tinh and Mai Sy Tuan Kandelia obovata Liu & Yong is a key species that has been planted in coastalareas of Northern Vietnam, mainly Quang Ninh, Nam Dinh and Thai Binh Provinces.In a natural development and ecological succession of mangrove forest, this speciesand others grow together in national mangrove forests [2]. Therefore understandingsecological characteristics of this species such as biomass and carbon accumulation couldsignificantly contribute to sustainable management of the mangrove forests. Scientists have developed a number of methods to estimate biomass (dry weight)of both inland and mangrove forest. These methods are divided into three categories: 1)the harvest method, 2) the mean-tree method and 3) the allometric method. The harvestmethod is not practical for measuring mature forests of the large amount of time andmanpower needed. Moreover, the harvest method is not reproducible because the trees aredestroyed. The mean-tree method is utilized only in forests that are relative homogeneousin terms of tree size. The allometric method uses allometic equations to estimate thewhole and partial weight of a tree referring to measured tree dimensions, includingtrunk diameter and height. This method is useful for estimating temporal changes inforest biomass by subsequent measurements (Komiyama et al.) [5]. However, allometricequations are site- and species-specific. Little research done using allometric equations to determine Kandelia obovata Liu& Yong biomass has been published or cited. The research presented in this paper is oneof the first studies in Vietnam that makes use of allometric equations to determine thetotal and component biomass of Kandelia obovata Liu & Yong. In addition, we comparedtwo ways of building allometric equations, i.e. determining parameters of equations. In term of carbon accumulation, the roots of mangrove trees are probably the mostimportant component. However, an understanding of carbon accumulation in roots as wellas in other components is limited because very few studies have been done on biomassproportion of mangrove trees. Ong et al. [7] have shown that in 20-year-old Rhizophoraapiculata mangrove trees, carbon is accumulated in the roots at a rate of 0.42 tC/ha/year,whereas accumulation in the canopy is at a rate of 0.52 tC/ha/year. We have not foundpublished data on carbon accumulation and biomass proportion of Kandelia obovata Liu& Yong. Therefore, in this paper we are the first to announce the biomass proportion ofKandelia obovata Liu & Yong in Vietnam. The results of this study are expected to significantly contribute to biomass andcarbon accounting for Kandelia obovata Liu & Yong mangroves in Nam Dinh Provinceas well as other areas of Northern Vietnam.2. Content2.1. Methodology2.1.1. Study site The present study was carried out on Kandelia obovata Liu & Yong that was planted10 - 20 years ago in Giao Lac Commune, Giao Thuy District, in Nam Dinh Province. Giao92 Allometric relationship and biomass partition of Kandelia obovata...Lac is locate ...