Arsenio B. Ella & Moreno L. Santander Jr.
Forest Products Research and Development Institute (FPRDI)
Department of Science and Technology, College, 4031 Laguna, Philippines
Tel: (+63-49) 536-2377/536-7408, Fax: (+63-49) 536-3630/536-7408
E-mail: Arsie_Ella@yahoo.com ; more8176@yahoo.com
Abstract
Thirty-two species of palosapis [Anisoptera thurifera (Blanco) Blume ssp. thurifera], naturally growing in the former logging concession of the Eastern Plywood Corporation in Llavac, Real, Quezon, Luzon Island, Philippines, were tapped (boxed) for resin or oil yield. Four diameter at breast height (dbh) classes: 30—39, 40—49, 50—59 and 60 cm and over were selected. Eight trees were designated for each of the four levels of aqueous sulphuric acid treatment at 0%, 40%, 50% and 60%. Resin yield per tree was determined and influence of rainfall, diameter classes and sulphuric acid concentration was studied. Months with higher rainfall in most cases gave greater resin yield. The effect of different diameter classes on resin yield was not statistically significant except in the case of 60 cm and over which gave the highest yield. The four levels of acid concentration had no significant effect on the resin yield.
Key words: resin yield, Anisoptera, Dipterocarpaceae
Introduction
Tapping or boxing of dipterocarp species for resin provides a livelihood for people in parts of the Philippines. In Quezon Province, for instance, many eke out their living by tapping dipterocarp species while waiting for the harvest of their farm crop. Some of those whose lands are already depleted of soil nutrients become full-time tappers. Boxing of this species thus provides a means of generating employment.
One of the most common resin producing dipterocarp species in the Philippines is Anisoptera thurifera (Blanco) Blume ssp. thurifera locally known as palosapis. The resin or ‘oil of palosapis’ is very similar to ‘balau’ from apitong (Dipterocarp grandiflorus Blanco). It is obtained in the same manner and is used for the same purposes, for example, in the manufacture of varnish that makes a brilliant, tough and durable coating (Brown 1921). Clover (1906), as cited by Brown (1921), said that the oil from palosapis resembles that from apitong, but dries much faster. In addition, the ‘oil of palosapis’ is light coluored, apparently homogenous in composition and so viscous that it can scarcely be poured.
The traditional method of obtaining resin is by boxing and refreshing by burning at frequent intervals to expose the cut (West and Brown 1921). This method is the same as that used in the production of dammar (Toñgacan 1973). Either by tapping or by accidental injury (Tanchico et al. 1934), resin is exuded from the resin ducts or gum canals found in the sapwood. This practice however, is still crude and often results in the entry of wood-destroying organisms, exposure to wind and rain often caused subsequent death of the tree.
Reports of studies conducted by Parameswaran and Zamuco (1976) based on the microscopy of the bark of four species of the so-called ‘Philippine mahogany’, and by Whitmore (1962) on the bark morphology of Malaysian Dipterocarpaceae, make no mention of the presence of resin ducts in the bark. Metcalfe & Chalk (1957), however, reported that in the young stems of dipterocarps, resin canals are always present in the pith, especially in the perimedullary region, and that they also occur in the phloem and cortex.
Few studies on the boxing of Dipterocarp species have been conducted. Toñgacan and Ordinario (1976) studied the boxing of apitong for balau production and the results revealed that monthly rainfall was found to have an inverse influence on monthly balau yield. Within the limits of sulphuric-acid concentrations used in the study, acid treatments were found to have no effect on balau yield. Nor were the significant effects reported for either interactions between rainfall and diameter, or rainfall and acid concentrations, on resin yield.
The objective of this study is to determine the effects of rainfall, tree diameter and sulphuric acid treatments on resin yield of boxed palosapis trees.
Materials and methods
The tapping experiment
The tapping or boxing experiment was conducted in the former logging concession of Eastern Plywood Corporation in Barangay Llavac, Real, Quezon, Luzon Island, Philippines, for a duration of 12 months. Thirty-two healthy palosapis trees belonging to four diameter classes: 30—39, 40—49, 50—59 and ≥60 cm (8 trees each) were included in the study. Four levels of sulphuric-acid concentrations: 0%, 40%, 50% and 60% (by volume) were applied to two trees each treatment. The experimental design of this boxing experiment is a 4 x 4 factorial in completely randomized design with only two replications owing to the scarcity of suitable, vigorous and healthy trees.
The tapping procedure
Palosapis bark was first cleaned or scraped off, using sharp bolo or wood chisel. The depth of tapping conformed to the thickness of sapwood as determined by incremental boring; the initial height of the box was about 25 mm and V-shaped to facilitate resin flow; the width was 1/3 of the girth of the tree. Subsequent rechipping proceeded vertically upward at width of about 20 mm to make sure that a minimum amount of the tissues destroyed by acid in the previous was tapping was removed.
Sulphuric acid solution was immediately applied evenly in a fine mist after cutting the streaks, using a US standard plastic squeezer of one-pint capacity. Plastic bags were used as receptacles. Each tree was properly labeled. The collection of resin was conducted weekly. Rechipping was done after each collection and sulphuric acid solution was applied. The amount of resin gathered was weighed and recorded.
The effect of variation in rainfall on resin yield in relation to different diameter classes and sulphuric-acid treatment was determined. Monthly rainfall data was obtained from the Philippine Atmospheric Geophysical and Astronomical Services Station (PAGASA), in Llavac, Real, Quezon, Luzon Island. The experimental site is under the second climatic type, having no dry season but with a pronounced maximum rain period from November to January.
Results and discussion
Table 1. Annual resin yield from different diameter classes.
Diameter class (cm) | Annual resin yield (kg/yr)* Acid concentration (% v.v) | Total Yield (kg/yr) | Average Yield (kg/tree/yr) | |||
0 | 40 | 50 | 60 | |||
30—39 | 7.51 | 5.49 | 8.22 | 8.74 | 29.96 | 3.74 |
40—49 | 5.05 | 9.77 | 6.75 | 4.92 | 26.49 | 3.31 |
50—59 | 7.61 | 7.19 | 4.26 | 7.92 | 26.98 | 3.37 |
60 & up | 10.59 | 14.68 | 13.31 | 8.69 | 42.27 | 5.91 |
r values | 0.59 | 0.74 | 0.30 | 0.14 | 0.58 | 0.58 |
p values | 0.4098 | 0.2697 | 0.7005 | 0.8561 | 0.4227 | 0.4218 |
Total Yield (kg/yr)** | 30.76 | 37.13 | 32.54 | 30.27 |
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Average Yield (kg/tree/yr) | 3.845 | 4.64125 | 4.0675 | 3.78375 |
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|
r values = correlation coefficients; p values = probability
*total yield of 2 trees; **total yield of 8 trees
Effect of the tree diameter on resin yield
The results are shown in Table 1. Statistical analysis revealed that diameter of the tree has no significant effect on the resin yield (Table 2). This lack of significance, however, is probably the result of low population (n) as comparison among the 4 diameter classes showed trees with diameter of 60 cm and up to have higher resin yield per tree than the trees of the other three diameter classes (Table 1). This might be due to the fact that larger trees have larger bark surface area and wider tapping cut exposure that have direct positive effect on the resin production. Table 1 also shows that the annual resin yield per tree is correlated to tree diameter (r = 0.58; p = 0.4218). A similar degree of correlation was shown at 0% acid treatment (r = 0.59; p = 0.4098) and slightly higher at 40% acid treatment (r = 0.74; p = 0.2697). However, at higher acid treatment levels (50% and 60%) poor correlation was observed (r = 0.3; p = 0.7005 and r = 0.14; p = 0.8561, respectively). This is consistent with the yield decrease at 50% acid treatment in 40—49 cm, 50—59 cm diameter classes and at 60% acid treatment in the 60 cm and greater diameter class. It can be seen that trees with larger diameter need higher acid concentration to lower their yield.
Table 2. Analysis of variance of total resin yield.
