Aquilaria malaccensis belongs to Thymelaeaceae family known as Agar wood, Eagle wood, Aloe wood and "Woods of the God". The agar wood producing species consisting of 13 species belong to 2 genera Aquilaria and Gyrinops that distributed throughout South East Asia. Phyto-geographically, the genus of Aquilaria are distributed from India (Bengal and Assam) to New Guinea through Burma (Tenasserim), Indo-China (Cambodia, Annam and Cochinchina), China (Hongkong and Hainan), Malaysia, Singapore, the Philippines, Indonesia and Thailand as well. While, Gyrinops spp. is distributed in Ceylon, Lesser Sunda Island, Celebes, Moluccas and New Guinea1. This plant is large evergreen tree more than 20 m tall and 1.5-2.4 m in girth with somewhat straight and fluted bole. Leaves are alternate 0.5-10 cm by 2-5 cm, oblong, lancelets or elliptic, caudate, acuminate and glabrous with slender nerves. Venation is parallel and petiole is 0.3-0.5 cm long. It is commercially used as fragrant and drugs. The tree contains plenty of oleoresin and has irregular dark patches. The aromatic resin obtained from this tree is one of the most famous and most expensive on the planet. It is found up to 750-1000 m, mostly at the bank of the rivers and streams and on ridges with sandy soils.
The A. malaccensis is on the brink of extinction in the wild and is now considered. Critically Endangered (CR) on the International Union for Conservation of Nature (IUCN) Red List. Due to large-scale logging operations, many forested areas where A. malaccensis was once abundant have been destroyed to rising demand for agar wood, as well as shortcomings in monitoring harvests and an increasing illegal trade. Since, 1994, agar wood has been included in Appendix II CITES under species group of Aquilaria spp.
This precious wood and its oil have a deep spiritual history and significance and they are mentioned in the oldest spiritual texts and it has been used for medicinal purposes2, aromatherapy3, pharmaceutical tinctures, asthma, rheumatism and other body pain treatment4. Many religious groups use it as a meditation incense to calm the mind and spirit. It is also the main ingredient of perfumery as well as cosmetic industry5,6. In the Middle East, both agar wood smoke and oil are customarily used as perfume2, in contemporary time it is widely used as incense, perfume and for the rapetis use. The trading value of pure agar oil7 is $30,000-40,000 kg1. Based on resin presence, agar wood chips sell8 from $30-$10,000 kg1. The global market for agar oil and other agar wood related products was estimated in the range of $6-8 billion and the major agar oil industrial buyer expects to exceed it in 2017 up to $36 billion9.
Agar wood plantation is exotic in Nepal some private plantation has been initiating for 25 years. There are no massive and systematic cultivation practices, but it is initiated as home garden plantation. Agar wood was introduced in Nepal by the people who returned from Assam, India and Thailand. There was no study carried out related to growth performance and cost benefit analysis after the inoculation of Aquilaria malaccensis in Nepal.
MATERIALS AND METHODS
Study site: Satyawati Rural Municipality ward number 8 Bharse, Gulmi district, Nepal, was selected as the study site. A Retired Indian Army person, Mr. Dhan Bahadur Pun has planted the seedling of Aquilaria malaccensis in 4.3 ha of land with mixed plantation in 2004, brought from Thailand. It is the only one registered planted private forest of Aquilaria malaccensis in Nepal. The study site lies at an altitude of 1400 m with latitude 20°07' N and longitude 83°46' E. The recorded mean temperature is 18°C and total annual rainfall is 1700 mm. The site lies in sub-tropical climatic region of Nepal10. Albizia species, Prunus spp. and Toona ciliata are the major natural tree species in this site. After the establishment of private forest, different silvicultural operations like weeding, cleaning were carried out with enrichment planting as shown in Fig. 1 and 2.
Sampling and data collection: The seedling process was done in random pattern mixed with horticulture species. The whole plantation area was divided into 3 sites namely Best, Medium and Worst, respectively based on its growth performance. Total 150 plants were measured in 2018 during field visit so, the trees were marked by using red ribbon, as gathered from the available records from DFO, Gulmi and private forest owner which includes the repetition in measurement. The diameter and height were measured. The diameter was recorded by using D-tape and heights were measured by using Abney’s level and simple tape. The secondary information was plantation time, seed sources and previous measurements.
Data analysis: Collected data were analyzed by using descriptive statistics such as; mean and inferential statistics to compare the growth among the sites. Mean Annual Height Increment (MAHI), Mean Annual Basal Area Increment (MBAI), Mean Annual Volume Increment (MAVI) and Mean Annual Carbon Increment (MACI) were calculated via using following formula:
|Fig. 1:||Map of study area
||Source: Field survey
Private plantation of Aquilaria malanccensis, (a) Aquilaria malanccensis plantation at worst site and (b) 15-year plantation of Aquilaria malanccensis
||Source: Field Observation, 2018
Basal area was calculated by using following formula:
where, D is diameter at breast height in cm.
Volume of tree was calculated by using volume calculation formula mentioned in inventory guide line, 2004:
where, volume in m3.
Above Ground Tree Biomass (AGTB) calculation: The equation developed by experts11 was used to calculate ground tree biomass:
AGTB = 0.0509×ρ×d2×H
||Above ground tree biomass (kg)
||Wood density of the species (g cm3)
||Tree height (m)
The carbon content was calculated by using following default factor as following12:
Carbon content (C) = 0.47×Total biomass
Besides, the cost benefit analysis was done comparing the price selling of the wood as timber and as a agar wood after inoculation.
Mean annual increment of Aquilaria malaccensis in different sites
Average height and annual height increment: The average height and mean annual height increment were varied according to site and age. The highest average height was found 5.1666±0.3333 whereas, mean average height increment was found to be 0.8611 m at 6 year age in plantation at site quality 1. So, the lowest mean average height increment was 0.5043 m at 12 years. It was around 0.6296 m at 9 years old (Table 1). There was significant difference in the height growth of Aquilaria malaccensis among 3 different sites: site 1, site 2 and site 3. Since, p-value was less than 0.05 and Tukey’s test showed that there were significant differences in the height growth of the trees among three different sites.
Average basal area and annual basal area increment: The average basal area and mean average basal area increment were varied according to site and age. The highest average basal area was found to be 1.7097 m2, whereas, mean basal area increment was about 10.258±3.859 m2 at 6 year plantation age in site quality 1. The lowest mean average basal area increment was d 0.9225 m2 ha1 at 12 years and was found 0.9522 m2 at 9 years old (Table 1).
There was significant difference in the basal area growth of Aquilaria malaccensis in three different sites, site 1, site 2 and site 3 at 95% confidence level (p<0.05). Tukey’s post hoc test showed that the data were normal. It showed that there were significant differences in the basal area growth of trees in 3 different sites at 95% confidence.
|Table 1:||Growing stocks and their mean annual increment
Comparison of selling cost after inoculation of Agar wood
|Source: Field data 2018|
Average volume and annual volume increment: The average volume and mean annual volume increment were varied according to the site and age. The highest average volume was found 0.002±0.001 m3, whereas, highest mean annual volume increment was found to be 0.00045 m3 at 6 year plantation age. It was decreasing according to the age in site quality 1. The lowest mean volume increment was about 0.00020 m3 at 12 years and around 0.0002 m3 at 9 years old (Table 1).
There was significant difference in the volume growth of Aquilaria malaccensis in three different sites: site 1, site 2 and site 3. Since, the p-value is less than 0.05. The data obtained were normal. Tukey’s post hoc test showed that there were significant differences in the volume of trees in 3 different sites.
Average carbon and mean carbon growth of Aquilaria malaccensis in different sites: Average carbon and mean annual carbon increment were varied according to site and age. The highest average carbon was 1.1676±0.477823 t and highest mean average carbon increment was found to be 0.1946 t at 6 year plantation age and it was decreasing according to the age in site quality 1. So, the lowest mean average carbon increment was about 0.1212 t at 12 years. It was around 0.1301 t at 9 years old (Table 1).
There was significant difference in the carbon growth of Aquilaria malaccensis in 3 different sites, site 1, site 2 and site 3 at 95% confidence level (p<0.05) and Tukey’s post hoc test showed that there were significant differences in the carbon growth of trees in three different sites.
Cost benefit analysis: According to the district rate and local rate, the management cost was calculated. It showed that total management cost was US $14300. Where, US$ = NRs110 including the major management activities.
If Aquilaria species is considered as other local species mentioned above then the selling amount would be US $1377.27. Table 2 showed the total inoculation cost for the production of agar wood would be US $7963.63 per 600 tree. It also shows the sale amount after agar wood formation. A single tree would give 3 items of good viz. fresh wood, semi resinous wood and resinous wood. Assuming the single tree would produce minimum 0.2 kg of agar wood and the selling amount would be high. Price calculation is based on $1 = NRs110.
The cost of the plantation establishment and management of Aquilaria malaccensis may be estimated as $14300 (1US$ = NRs 110) and considering the total sealable Aquillaria malaccensis volume with other merchantable species of Gulmi like Pinus roxburghii (Salla), Toona cilitae (Tooni) and other species, the total gained price may be 727, 363 and $272, respectively, based on local market price.
On the other hand, if this Aquilaria malaccensis tree is inoculated then the cost and selling price of this species is different. The cost for the inoculation may be $13.27 per tree whereas, the selling price after the inoculation and formation of agar wood may be $511609 in total production and $852.68 per tree. The net profit after inoculation is estimated as $489345.45 and the benefit cost (B/C) ratio is $21.97.
This result gives the conclusion that Aquilaria malaccensis species would not be valuable unless it produce agar wood. Agar wood can be gain naturally as well as artificially. Natural process is long and unsure in production of agar wood in all tress. So, to gain profit artificial, inoculation is necessary. In this study the farmers has tress of about 12 years which were suitable for inoculation on age basis, but on DBH basis they had not gain desirable DBH. To compensate the further management cost if inoculation is done it would gain reasonable profit. This study recommended for inoculation.
The growth rates of trees that have sufficient space to grow rapidly and at the same time do not develop excessive limberness provide a practical standard for estimating potential growth. Some study showed that A. malaccensis is fast growing during early growth age at five years old stands with mean annual increment diameter and height of 2.8 cm and 2.0 m, respectively13. This growth increment results was also found to be similar in other exotic species of A. crassna and A. sinensis. Another expert stated that they are fast growing trees, hardy and in areas with adequate moisture can achieve 10 cm DBH within 4-6 years3.
This study found that mean annual height increment (m) and DBH (cm) of A. malaccensis was fast earlier stages, but it decreased gradually with age. Mean annual height increment was highest for the 12 years old plantations of best sites height increased was 0.5 m per year. Height increment was also 0.86, 0.62 and 0.50 m in 6, 9 and 12 years old plantation at best sites, respectively. It was observed that the highest mean annual DBH increment (0.58 cm per year) was in 6 years old plantations at best sites. The lowest mean annual DBH increment (0.167 cm) was for the 12 years old plantation at poor sites.
This study showed that the mean annual diameter increment of good site for 6, 9 and 12 years was 0.58, 0.36 and 0.31 cm, respectively as well as mean annual height increment of good site 6,9 and 12 years was 0.86, 0.62 and 0.5 m, respectively. The mean annual height increment and diameter increment of the tree was found to be in decreasing trend with an increasing age. This result was in agreement with Hossen and Hossain14, who stated that “there is decreasing trend in mean annual height and diameter increment with the increase in tree age”. Likewise, the basal area of the tree was also found in decreasing with the age.
Another study3 showed that the annual growth rates of DBH ranged from 0-1.95 cm/yr at Pasoh Forest Reserve, Malaysia. It reported that the distribution of growth rates of DBH was strongly skewed with a mean value of 0.33 cm/yr and a median value of 0.22 cm/yr. The growth rates achieved by the 12 fastest growing trees (90% percentile) exceeded 0.80 cm annually3.
The growth of Aquilaria malaccensis was rather low at 0.33 cm per year in native forests. Nevertheless, tree growth can reach upto 0.8-1 cm/1 yr in Peninsular, Malaysia3.
In the same way, the entire study showed that, the average height, average, diameter and average, volume along with average annual height increment, average annual diameter increment and average annual volume increment of 4 (6, 9, 10 and 12) different years. Similarly, annual height increment, annual diameter increment, annual volume increment and basal area increment have found to be ranged from 0.8-0.16, 0.5-0.16 cm and 0.00046-0.000035 m3 and 1.70-0.26 m2, respectively.
Aquilaria malaccensis tree would be benefitted only after the agar wood production. For economic benefit inoculation is necessary in the Bharse, Gulmi. The benefit cost (B/C) ratio is 21.97. It showed after inoculation benefit would be gained. This supported by the research of Bangladesh15, Depending on BCR analysis, it was clearly seen that agar wood production is highly profitable which could change the economic condition of the agar wood growers by 9.31 per tree.
The overall growth performance of A. malaccensis with respect to height, diameter, volume and basal area was significantly different. The growth response of A. malaccensis of Bharse Gulmi has not shown good performance. This study had given picture that to gain benefit from the plantation inoculation process had been started soon. Along with it has created new horizon of research in this species in Nepal for further extensive plantation. As it is new species to new Nepal proper research and study deemed necessary for the deterrence of huge economic loss of the farmer. This study had given picture that the inoculation process is deemed necessary to gain profit from the plantation. If inoculation is done then benefit cost (B/C) ratio would be increased by 20 folds. Detail study should be carried out to find the growth performance of this species which were planted in Terai region to compare within it. The A. malaccensis would be valuable only after it produce agar wood so for that various research and pilot project for inoculation should be done.
The Aquilaria malaccensis is first time introduced in Gulmi, Nepal. Local people and even academician have very limited knowledge about this species in Nepal. This research paper will be a mild stone for those who are interested to commercialize the forestry plants. In addition, study will provide the base line information to know the growth of this species as well as the economic value. These are major significance of this study.