**1. Introduction**

Tree biomass is a product from photosynthesis as a result of carbon sequestration by tree. A tree can absorb approximately 23 kg of carbon per year. Indeed, a tree can increase biomass as an effect of tree growth and loss biomass through mortality that is due to natural death or logging. Tree biomass can be divided into above (AGB) and below ground biomass (BGB) in which the AGB includes the stem, leaves and branch biomass whereas the BGB is the biomass of tree roots. Each component of the AGB varies in biomass density. The estimation of biomass is significantly important for the environment which is a critical aspect of studies of carbon stocks and the effects of carbon sequestration on the global carbon balance. In recent years, carbon dioxide (CO2 ) has received much attention from the world because its concentration in the atmosphere has risen to approximately 30% above natural background levels [1]. The need for biomass and carbon stocks estimation is critical and can be measured using destructive or non-destructive sampling method. That is why a field inventory is conducted where the measurement of tree diameter is recorded to estimate the biomass of tree and later the carbon stocks. According to Brown [2], for closed forest such as Pahang National Park (PNP), a minimum diameter of tree to be measured is greater than or equal to 10 cm. However, for open or secondary forest, a smaller minimum diameter should be chosen [2, 3].

this study is expected to provide baseline information and an understanding on the role of trees in sequestrating carbon. This study aims to estimate the AGB and BGB as well as the TTB of LDF, RF, and HDF in PNP. This study also aims to estimate the carbon stocks of LDF, RF, and HDF in PNP, and to investigate the interaction between forest and five similar family and

Biomass and Carbon Stocks Estimation of Lowland Dipterocarp, Riparian and Hill Dipterocarp…

http://dx.doi.org/10.5772/intechopen.76699

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This study was conducted in PNP in the state of Pahang. PNP has a tropical climate with an annual rainfall of about 2.260 mm and rich in forest vegetation such as trees, climbers, shrubs, epiphytes and palms. Average temperature throughout the year ranges from 20 to 35°C with more than 80% humidity [6]. There are differences in the soil series in the LDF, RF and HDF

This study was conducted in three types of forests of LDF, RF and HDF of PNP and the location of study area are shown in **Figure 1**. The description for each location is summarized in **Table 1**. A total of 60 plots were set up in which each forest contains 20 plots measuring at 20 × 20 m (0.04 ha). Study plots for LDF were located in Kuala Keniam while plots for RF were scattered; 10 plots were located along Keniam River while another 10 plots were located along Tembeling River near to Kampung Pagi. As for the HDF, data collection was conducted in the

For the field measurement, diameter at breast height (DBH) tape was used to measure the diameter of sampled trees with DBH ≥ 10 cm which is 1.3 m up from the ground [8]. In the case of big buttressed stems, the tree height was measured just above the upper end of plank buttress [9]. Each tree was permanently tagged using laminated label. Tree height was measured using a clinometer, a device that can be used to measure the slope to points on a tree, which can subsequently be used to determine the tree height. The sampled trees were identified to species level and for unknown species, the botanical specimens (e.g. leaves, flower or fruit) were collected for species identification at herbarium laboratories of Universiti Kebangsaan

Throughout this study, AGB was estimated using Kato et al.'s function [9] (Eqs. (1)–(4)) while BGB using a function from Niyama et al. [10] (Eq. (5)). According to reference [10], the total root biomass is the summation of coarse and fine roots in which fine root is defined as root with diameter less than 5 mm. The TTB is the summation of AGB and BGB. From the values of measured DBH and tree height; the dry mass of stem, branch and leaves of sample trees were

*Ms* = 0.0313 (*D*<sup>2</sup> *H*)0.9733 (1)

mainly due to the variations of parent material between localities [7].

Teresek Hill at an elevation around 330 m above sea level.

Malaysia (UKM) and Forest Research Institute Malaysia (FRIM).

estimated. The equations used to estimate these components are as follows:

**2.2. Data analysis of tree biomass**

five similar species in the study areas.

**2.1. Study area and field data collection**

**2. Materials and methods**

Most of the researches focus on the estimation of the AGB rather than BGB because the process to estimate the AGB is easier and less complicated as compared to BGB. In addition, the above ground tree components are the largest contributor of biomass from the total tree biomass (TTB) whereas the BGB only constitutes a small portion of the TTB. Lajuni and Latiff [4] reported the BGB value in their study plots at Khao Chong forest was one tenth of the AGB. Besides, a study conducted by Mohamad [5] in Kenaboi Forest Reserve, Negeri Sembilan found that root biomass in his study plots was six times smaller than the AGB with values of 463.81 and 73.57 t/ha for AGB and BGB, respectively.

Tree biomass and carbon stocks also varied in accordance to forest types and geographical regions. As such, forest biomass and carbon stocks in tropical forest are higher than temperate forest. This might be due to the different in tree species and climatic condition between both forests. Furthermore, in any forest types, tree biomass and carbon stocks in primary forest are higher than secondary forest. Secondary forest is a forest that has been logged or naturally disturbed whereas primary forest is a forest that has never been logged and free from anthropogenic disturbance. In this case, PNP is considered as a primary forest since anthropogenic activities such as logging have never occurred in this forest. Therefore, it is expected that more carbon can be stored by forest biomass in PNP.

Despite the multi-functional roles of forest biomass, lack of research had been conducted with regards to the extent of AGB, BGB and carbon stocks in lowland dipterocarp (LDF), riparian (RF) and hill dipterocarp forests (HDF) in PNP. In addition, information on biomass estimation and carbon stocks from tree inventory data is currently unavailable for protected forest of PNP. Therefore, this study was conducted to provide the estimation of the AGB, BGB and carbon stocks with respect to different localities in PNP. Considering the fact that biomass represents the role of tree as a key indicator of carbon source and sink, the information from this study is expected to provide baseline information and an understanding on the role of trees in sequestrating carbon. This study aims to estimate the AGB and BGB as well as the TTB of LDF, RF, and HDF in PNP. This study also aims to estimate the carbon stocks of LDF, RF, and HDF in PNP, and to investigate the interaction between forest and five similar family and five similar species in the study areas.
