Carbon Sequestration Potential of Fruit Tree Plantations in Southern Philippines
Global warming is recently considered a major concern worldwide due to massive emissions of greenhouse gases to the atmosphere. Trees are seen as one of the mitigating measures of this problem due to its role in carbon sequestration. This study is aimed to assess the carbon sequestration potentials of 15 year old Mango (Mangifera indica Linn. 12 year old Rambutan (Nephelium lappaceum L. and the 32 year old Santol (Sandoricum koetjape Merr. in Bukidnon. Potential carbon sequestered was determined in various carbon pools (trees, understorey, litters and soil) of the three different fruit crop plantations. Field measurements and laboratory analysis were used to measure biomass density and carbon stocks of the samples. Results revealed that among the three plantations, the 32 year old santol plantation had the highest value of total carbon stored with 203.62 ton/ha. This was followed by the 15 year old mango plantation with 122.34 ton/ha. The 12 year old rambutan plantation had only 112.18 ton/ha carbon storage. In terms of carbon pools, the soil had the highest carbon stocks in all plantation at 113.21 ton/ha, 96.76 ton/ha, 67.56 ton/ha for santol, rambutan and mango, respectively. The carbon stocks for the trees were next highest with 86.02 ton/ha (Santol) 52.46 ton/ha (mango) and 13.13 ton/ha (rambutan) The least among the carbon pools is the understory with 0.5 ton/ha, 0.7 ton/ha and 0.36 ton/ha for rambutan, mango and santol plantations, respectively. Findings of this study suggest that fruit tree crops are potential carbon sink and must be promoted as a land use practice to help mitigate climate change. *Corresponding Author: Rico A. Marin ricomarin@yahoo.com Journal of Biodiversity and Environmental Sciences (JBES) ISSN: 2220 6663 (Print) 2222 3045 (Online) Vol. 8, No. 5, p. 164 174, 2016 http:/www.innspub.net J. Bio. Env. Sci. 2016 165 Janiola and Marin Introduction Forests are crucial to the well being of humanity. Furthermore, it provides foundation for life on earth, through ecological function and furnished a wide range of essential goods and services (Carandang, 2005) Today, world's forests are under pressure due to the modernization of life and increasing human population. According to Carandang (2005) conversion and degradation of forests are forms of forest destruction. Climate change and global warming are the associated effect due to the destruction of world's forest. Another form of forest destruction, which is also a contributor to the increase of atmospheric carbon is land use change of forest. Increasing agricultural productivity is a primodial concern in many developing countries like the Philippines and it is a driver of change for land use purposes in the forest (Sace, 2002) The deteriorating global environment and destruction of forest around the world had generated concern among nations, governments, and international organization (AFPSOS, 2009) Carbon has been associated with evolving discussion of climate change and global warming (Bowyer et al. 2012) On the positive note, however, tropical forest had the largest potential to mitigate climate change and global warming through conservation of existing carbon pools (Lasco and Pulhin, 2009) Today, a lot of researches have been conducted regarding carbon stock assessment. Most of these researches were conducted within natural forest and agroforestry farms. According to van Noordwijk (2002) a more refined Carbon accounting system is clearly needed to clarify changes in the terrestrial carbon storage and to understand the present carbon situation in various land cover types to include grassland, agricultural land and fruit tree crop plantation. The interest of this study is to determine the carbon stock of fruit crop plantation, which is believed to have very limited information on carbon stock at present. Materials and methods Location of the study A study was conducted in the fruit tree plantation project of Bukidnon, Philippines. The three fruit plantations were the 15 year old Mango (Mangifera indica Linn. Plantation, 12 year old Rambutan (Nephelium lappaceum L. Plantation and 32 yearold Santol (Sandoricum koetjape Merr. Plantation. Fig. 1. Location map of fruit crop plantation production. J. Bio. Env. Sci. 2016 166 Janiola and Marin The area was located at the center of the province of Bukidnon which belonged to the third climatic type of the Philippines, having no very pronounced season usually from November to April and the rest of the year was wet. The elevation of the area ranged from 200 260 meters above sea level (Fig. 1) Sampling design The study made use of the Randomized Complete Block Design (RCBD) replicated two times. The treatments of the study includes: A= 12 year old Rambutan Plantation B= 15 year old Mango Plantation C= 32 year old Santol Plantation Establishment of sampling plot The established nested sampling plots were based from the method used by Hairiah, et.al (2010) Two 5 m x 40 m plots were being established in each fruit plantation. Nested plots of 1 m x 1 m and 0.5 m x 0.5 m were established within the 5 m x 40 m for soil, for litter and understory sampling, respectively. With the used of GPS receiver, geoposition of each plot was recorded. Carbon stock calculation Aboveground Live tree biomass Data collection to estimate carbon density was conducted using the methods described by Hairiah et al. (2010) This method had been applied in many carbon related studies in the Philippines. Two 200 m2 (5 m x 40 m) quadrats were established in each fruit plantation. The two quadrats represent replication per site. The plot was established by running a 40 m centerline through the area. The trees with Diameter at Breast Height (DBH) of 5 cm to 30 cm were measured as samples within 2.5 m of each side of the 40 m centerline. A sample plot of 20 m x 100 m was established per site to measure the diameter and height of tree greater than 30 cm DBH. For carbon computation of fruit trees, the equation by Unruh et al. (1993) as cited by (Abucejo, 2012) was used was used. Cft (kg) (Yftb) (0.45) Where:Cft Carbon yield of fruit trees Yftb Fruit tree biomass exp[ 2.4090 0.9522*In(D2HS) D DBH (cm) H Tree Height (m) S Wood density equivalent to 0.57 0.45 Carbon Content of fruit trees