IJERD – International Journal of Environmental and Rural Development (2021) 12-1

Research article
erdConservation and Ecological Threats of Agarwood (Aquilariasp.) on Leyte Island, Philippines
LORRAINE CRISTY E. CENIZA
Visayas State University, Baybay City, Philippines
Email: lorrainecristy.ceniza@vsu.edu.ph

JIMMY O. POGOSA
Visayas State University, Baybay City, Philippines

SUZETTE O. LINA
Visayas State University, Baybay City, Philippines

MARLITO M. BANDE*
Visayas State University, Baybay City, Philippines
Received 30 December 2020

Accepted 30 June 2021(*Corresponding Author)

Abstract Aquilaria is a genus of about 20 species distributed mainly in the Indo-Malesianregion. The genus Aquilaria belongs to the Thymelacaceae family of Indo-Malayan trees
known for producing the world's most expensive oils, which are naturally occurring throughout
the Philippines. Aquilaria is well known for the production of agarwood which is a highly
wanted forest product of substantial economic value. In the Philippines, there is limited
published information on the physical condition, habitat structure, and ecological threats ofAquilaria, which is a crucial factor to determine the optimum requirements to developAquilaria production system. Hence, this study was conceptualized to assess the habitat
structure of Aquilaria as well as its conservation and ecological threats in the wild. Assessment,
surveys and interview were conducted to gather on-site atmospheric data as well as ecologicalthreats of Aquilaria in the wild. Soil collection was also gathered to analyzed soil properties.
The results revealed that there were two species of Aquilaria documented in the study site,namely: A. malaccensis and A. cumingiana. Moreover, the soil chemical properties are notsignificant between different topographic expositions, but it is acidic and generally have low
nutrient status. Furthermore, the conservation and ecological threats documented in the studysite are unsustainable harvesting, a massive collection of regenerant, and inflecting damage of
Aquilaria by punching nails or drilling holes in the trunk of standing mature tree. Therefore, it
is highly recommended that Aquilaria should be protected, particularly A. malaccensis, since itis rare and considered a new record of occurrence to Leyte Island as one of the major findingsof the study. The establishment of Aquilaria based production system is necessary as an option
to reduce the rampant illegal poaching of agarwood in the wild but should be established on
private land and registered with the Department of Environment and Natural Resources(DENR).
Keywords Aquilaria, topographic expositions, ecological threats, habitat structure

INTRODUCTION
Aquilaria is a genus of about 20 species (International Plant Names Index, 2015), distributed mainly in
the Indo-Malesian region. Agarwood also known as gaharu in the South East Asia, oud in the MiddleⒸ ISERD

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East, chen xiang in China, jinkoh in Japan and agar in India is a highly valuable aromatic dark resinousheartwood of Aquilaria species (Liu et al., 2017). The genus Aquilaria belongs to the Thymelacaceae
family of Indo-Malayan trees known for producing the world's most expensive oils (Lee & Mohamed,2016). Fernando et al. (2018) reported that Aquilaria apiculata, A. filarial, A. malaccensis, A.
brachyantha, A. cumingiana, A. urdanetensis, A. citrinaecarpa, and A. parvifolia are just eight out of
the 24 species of agarwood oil-producing trees in the world that are naturally occurring in thePhilippines. In Leyte, Biliran, Samar, and Negros, Aquilaria sp. is locally known as lapnisan and laneti.
Agarwood is traded in several raw forms, ranging from large sections of the trunk to finishedproducts such as incense and perfumes (Barden et al., 2000). They reported that natural stocks arelargely depleted by overexploitation, and the demand for agarwood is higher. Foreign nationals arenow searching agarwood in the Philippines, specifically Leyte, Biliran, Samar, and Negros. There havebeen reports in the field that sometimes these nationals are impatient to find Aquilaria since it wasreported by Abdin (2014) that global agarwood prices can be ranging from US$ 20 – 6,000 per
kilogram for the wood chips depending on its quality or US$ 10,000 per kilogram for the wood itself.
There was a destructive exploitation of agarwood that has badly affected the wild population of
all Aquilaria species due to widely used as therapeutic perfumes, traditional medicine, religious
purposes and aromatic food ingredient (Tan et al., 2019).
There is a scarcity of information on the physical condition, habitat structure and ecologicalthreats of Aquilaria which is crucial factor to determine the optimum requirements to develop
Aquilaria based production system. This study was conceptualized to assess the habitat structure of
Aquilaria and its conservation and ecological threats in the wild.
OBJECTIVES
1. To characterize the habitat condition and structure of Aquilaria on Leyte Island; and2. To determine the ecological threats of Aquilaria in the natural habitat.
METHODOLOGY
Selection of the Study and Sampling Site
The study was conducted at the selected site of Leyte Island. The major criteria in selecting thesampling site were the presence of Aquilaria in the area which was selected through a preliminary
survey by directly collecting information from reliable individuals (i.e., poachers, a buyer of agarwood)
further identify the exact location of Aquilaria trees in the wild. Furthermore, the study site wasselected based on the incidence of rapid and over-harvesting of the Aquilaria matured trees andregenerant, respectively, during the pre-assessment.
Data CollectionThe atmospheric data, i.e., light intensity (lux), temperature (°C), and relative humidity (%) werecollected on-site to determine the climatic factor that may affects the habitat structure of Aquilaria
under natural condition. The data was collected in each exposition at an interval of two hours, startingfrom seven o’clock in the morning until five o’clock in the afternoon.
Soil samples were collected in the study site. The soil samples were then brought to the laboratory
to analyze soil chemical properties such as soil pH, soil organic matter, total nitrogen, and available
phosphorus.

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To determine ecological threats, an actual field survey and photo documentation of poached
Aquilaria trees were done. Likewise, an interview was conducted to collect information from seedlinggrowers, poachers, and agarwood buyers.
Data Encoding and Statistical Analysis
All data gathered were collated, encoded, and summarized using an electronic spreadsheet editor,Microsoft Excel 2013. The data were analyzed using the Statistical Package for Social Science (SPSSversion 20).
The atmospheric data were analyzed descriptively. The variability of the mean of soil chemicalproperties was analyzed using the one-way analysis of variance (ANOVA). Moreover, in a case where
the significant variations at p≤0.05 was identified, Tukey and Least Squares Differences (LSD) wascarried out to compare means.
RESULTS AND DISCUSSION
Microclimatic Conditions in the Study Site
The data on atmospheric parameters such as light intensity, air temperature, relative humidity, andrainfall are presented in the figure below to describe the on-site condition of the study area.

ABCFig. 1 Microclimatic conditions between different expositions of the study site
at different time intervals
Results show that west-oriented topographic exposition had higher light intensity compared toother topographic expositions (Fig. 1A). Meanwhile, the average temperature at all periods of datacollection had an increasing trend from seven o’clock in the morning until three o’clock in theⒸ ISERD124

IJERD – International Journal of Environmental and Rural Development (2021) 12-1afternoon but had a slight drop at five o’clock in the afternoon (Fig. 2B). On the other hand, the resultof the relative humidity had a slight variation (Fig.1C).
Soil Chemical Properties
Table 1 shows the chemical properties of the study site. Statistical analysis showed no significant
difference between soil chemical properties of the study site between different topographic expositions.
Soil pH was very strongly acidic, and soil organic matter content was moderate. The total nitrogen in
the study site is medium, as interpreted by Landon (1991). According to Krofranek et al. (2007), total
N is deficient mostly in the tropics since it undergoes various losses such as leaching and volatilization.
The results on total N can therefore, be attributed to the lower soil organic matter in the study site.
Table 1 Soil chemical properties within study site between different topographic expositions
Expositions

pH

North-oriented
East-oriented
South-oriented
West-oriented

4.90 ± 0.18
4.85 ± 0.18
4.90 ± 0.18
4.74 ± 0.18

Soil Organic Matter(%)
4.27 ± 0.63
4.11 ± 0.63
4.46 ± 0.63
4.01 ± 0.63

Total Nitrogen(g/kg)
0.21 ± .03
0.21 ± .03
0.22 ± .03
0.20 ± .03Available Phosphorus(mg/kg)0.96 ± 0.16
0.59 ± 0.16
0.92 ± 0.16
0.63 ± 0.16

On the other hand, according to the sufficiency ranges of soil of Landon (1991) the available P in
the study site is very low.
Therefore, the result of this study supports the findings of Piamonte et al. (2014), where theyfound out that the soil in Mt. Nacolod Mountain Range (Abuyog-Silago-Hinunangan-St. BernardLibagon-Mahaplag) is classified as Ultisols, which is characterized as acidic and generally have low
nutrients status.
Conservation and Ecological Threats
Unsustainable harvesting:In the study site, five illegally-cut matured Aquilaria were documented and recorded. Meanwhile, acommunity resident began harvesting Aquilaria in the forest in June 2019. According to the respondent,
since it was difficult for them to identify the exact Aquilaria trees, they would randomly cut trees
without properly distinguishing them and chopping them into pieces (Fig. 2A). Until eventually,
traders from other countries (China and Taiwan) and other places within the Philippines (Mindanaoand Samar) came and trained them to identify and distinguish the Aquilaria tree.

ABFig. 2 Local practice in harvesting Aquilaria in the study siteAⒸ ISERD

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The traders instructed them that a matured Aquilaria tree that looks rotten or unhealthy has most
likely agar in it, whereas those that look firm and healthy are not good. This information wasconfirmed by the study of Rasool and Mohamed (2016) that agarwood formation is often linked to thephysical wounding or damage of Aquilaria trees caused by thunder strike, animal grazing, and pest anddisease infestations.
According to the respondents, Aquilaria is cut into pieces from trees to reveal the resinous product(Fig. 2B). Apparently, poachers are chopping down trees faster than they can grow, including forest
across neighboring towns. According to Ng et al. (1997), not all Aquilaria trees produce agarwood,
estimating that only approximately 10% of wild Aquilaria spp. produce resin.
Furthermore, respondents stated that they are more eager to search for agarwood than work as ahired labor or harvest copra because of its immense value. They further explained that they earn higher
income from agarwood than farming and working as laborers. Harvesting Aquilaria and sellingagarwood enable them to triple their income, which consequently improved their living condition. For
instance, most of the respondents could buy new motorbikes, repair or enhance their houses and buy
property (such as land).
Massive collection of regenerant:
Based on the interview results, in 2019, when Aquilaria became widely known, the value of seedlingrose to 500 to 1000 Pesos. The seedling, particularly from Aquilaria malaccensis (Fig. 3A), generates
higher income since wildlings are abundant in the forest. According to Chua (2008), Aquilaria
malaccensis produces seeds after 7-9 years, while some other species produce seeds only once in theirlife cycle.

AB

Fig. 3 Aquialaria malaccensis seedlings (A) and Aquilaria cumingiana seeds (B)owned by one of the respondents
As for Aquilaria cumingiana regenerant (Fig. 3B), only few are being propagated after collecting
seeds. According to the seedling growers, its value is worth 40,000 Pesos per kilo. The seedling grower
clarified that none of the seeds survived due to insufficient knowledge on how to properly propagate
Aquilaria seeds and the appropriate time of collecting the matured fruits.
Inflecting damage to the matured Aquilaria trees:
In the study site, landowners and poachers have created an illegal method of inflecting matured
Aquilaria. This is by punching nails or drilling holes on the trunk of standing matured Aquilaria (Fig.
4). They believe that by damaging the trunk using nails, it will gradually trigger infection andeventually develop agar inside. This method is widely visible on the study site.
Moreover, according to Ng et al. (1997), the age of the tree, differences in the tree caused byseasonal variation, environmental variation and genetic variation of Aquilaria spp. may also play anessential role in agarwood formation.

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Fig. 4 Locally practiced method of inflecting (by punching nails and drilling holes
at the trunk) matured Aquilaria species in the community
CONCLUSIONThe results show that west-oriented topographic exposition had higher light intensity, while theaverage temperature during the conduct of the study had an increasing trend from seven o’clock in themorning until three o’clock in the afternoon but had a slight drop at five o’clock in the afternoon.
The result of the relative humidity showed that the east-oriented and north-oriented topographic
location got the highest and lowest average of 86.29% and 84.26%, respectively.
The soil chemical properties are not significant between different topographic expositions.
However, the soil on the study site is acidic and has a generally low nutrient status. The ecologicalthreats recorded in the study site were unsustainable harvesting, a massive collection of regenerants,
and inflecting damage of Aquilaria by punching nails or drilling holes in the trunk of a mature standing
tree.
Therefore, it is highly recommended that Aquilaria should be protected particularly Aquilaria
malaccensis since it is rare and is considered a new record of occurrence to Leyte Island. The
establishment and development of an Aquilaria-based production system are necessary as analternative option to reduce the rampant illegal poaching of agarwood in the wild. Furthermore, theAquilaria-based production system should be established in private land and registered with theDepartment of Environment and Natural Resources.
ACKNOWLEDGEMENTS
We extend our gratitude to the Institute of Tropical Ecology and Environmental Management, Visayas
State University, Baybay City, Leyte and to the Municipality of Abuyog, Leyte, for the great support
for this study.
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