0028-B4
A. B. ELLA, M. DR. RAMOS and R. E. CORTEZ, JR. 1
Almaciga (Agathis dammara Lamb. Rich.) trees naturally growing in sitios Mayagbon and Kamugsan in Barangay Concord, Hinabangan, Samar were tapped for resin production at three different lengths (10, 20 and 30 cm) at same width (2cm) and same depth enough not to reach and damage the cambium. Ethylene application (one spray per tapped cut applied soon after cutting) using the commercial ethrel was done at 4 concentrations (0, 0.5, 1.5 and 2.5%). Retapping (or rechipping) after the weekly resin harvest was done immediately above the previous tapped cut. Thirty-six trees were tapped to have three replications per treatment (one tree one replication). The effect of tapping length and ethrel concentration on resin yield was studied throughout the one-year tapping schedule.
Increasing tapping length directly influenced resin yield with the 30-cm length giving the highest yield. Ethrel concentration significantly affected resin yield wyhich was highest at 2.5%. A workable method of tapping almaciga using 2.5% ethrel concentration at 30-cm tapping was developed for future implementation.
The almaciga tree grows naturally in almost all Philippine forests. The Philippine government prohibits the felling of the tree and because of this, utilization is limited to its resin, known in world trade as almaciga resin or Manila copal. Almaciga resin is used in the manufacture of varnishes, paints, soaps, plastics, printing ink, linoleum, shoe polish, floor wax, etc.
Although regarded as a minor forest product, almaciga resin is one of the country's dollar earners. In 1999, The Philippine Forestry Statistics reported that 336,000 kg of almaciga resin valued at US$247,000 was exported.
Almaciga resins intended for international markets are obtained by tapping the tree, rather than collecting fossil resin from the ground. To obtain the Manila copal, the bark of the trunk is incised. Fresh cuts are made at suitable intervals a few days or a week or more, gradually moving up the tree, and the exudates are collected. In the Philippines, known as the second highest producer of the copal, next only to Indonesia (Copper, 1995) research has been conducted on tapping methods very similar to those used in tapping pine trees which involves the use of sulfuric acid as chemical stimulant. In previous test experiments, tapping of Philippine resin has been confined to the application of 50% sulfuric acid as resin inducer, viz., Benguet Pine (Pinus insularis, Ind); for oleoresin, apitong (Dipterocarpus grandiflorus Blanco) for balau resin, palosapis (Anisoptera thurifera) (Blanco) Blume spp. thurifera) for oil of palosapis; almaciga for Manila copal, and lately Canarium spp. for Manila elemi. Ella and Toñgacan in their studies on boxing apitong (1976) and palosapis (1987) and tapping Canarium (1998)confirmed that within the limits of sulfuric acid concentrations used in both studies, acid treatment had no significant effect on the yields of balau, palosapis oil, and Manila elemi.
Recently, a chemical company synthesized a new compound with the brand name Ethrel. All ethrel formulations containing 2-chloronosthylpbosphoric acid produce numerous physiological effects when applied on plant tissues. Reports from abroad indicate that ethrel is very effective to ripening various fruits, viz., banana, pineapple, mangoes, etc.
Yamamoto and Kozlowski 1987) revealed in their studies that application of Ethrel to vertical stems of Pinus densiflora seedlings greatly increased their ethylene contents but he did not induce formation of certain characteristics of compression wood when applied to tilted seedlings. The scientists have concluded that ethrel treatment indiced formation of longitudinal resin ducts in the Xylem whereas flooding or tilting of stem did not.
Experience has shown that stimulants are important for efficient exploitation of most clones at some stage during the average 30 year life span of rubber trees (Hevea brasiliensis). Brushing at 1½ to 2½ inch strip of bark directly below the tapping cut with a 10% concentration of ethephon in palm oil had increased latex flow and dry rubber yields by 100% or more on commercially important clones. Although explanation of the stimulation mechanism is still somewhat theoretical, ethephon treatment does prolong latex flow when the tapping cut was made (de Wide, 1970). Furthermore, the greatest increase in dry rubber content is achieved when ethephon in used with the conventional Half-spiral cut tapped every two days. Increased yields can also be obtained with shorter ¼ or 1/3 spiral tapping cuts and reduced tapping frequencies to 3,4 and even 6-day intervals. Stimulating latex production from rubber trees is the first commercial use for ethephon.
Application of ethephon was initially tried in the Philippines by Caliano (1984) in his experiment at the Philippine Industrial Crops Research Institute, University of Southern Mindanao in Cotabato. His study showed that stimulation of rubber trees with 2.5% ethephon applied either 10 or 4 times a year lowered the dry rubber content of the latex in all tapping systems carried out. On the other hand, studies in Ivory Coast conducted by Eschback and Banchi (1984) showed that the use of ethphon as latex yield stimulant in rubber trees decreased the tapping intensity, maintained the level of growth and yield and resulted to good physiological characteristics and fewer dry trees.
The application of ethrel to stimulate resin flow of plants producing exudates like almaciga for resins had not yet been tried. A study therefore was initiated at FPRDI to determine whether the use of ethrel, as a source of ethylene, would stimulate resin flow in almaciga under local conditions.
Application of ethylene to forest tree species like almaciga to possibly induce and sustain resin yield is the first of its kind. It is easy to handle and apply unlike sulphuric acid which is a strong chemical compound that must be handled with care.
A study on the application of ethrel as a source of ethylene to enhance resin flow is timely for the production and sustainable resin yield for commerce and industry.
1. To study the influence of ethrel application and tapping length on almaciga resin production;
2. To determine whether time of tapping (month) and treatment of ethrel and tapping length affect almaciga resin yield, and
3. To contribute to the improvement of current methods of inducing almaciga resin production as well as develop a workable and affordable method of tapping almaciga trees.
The tapping experiment was conducted in Barangay Concord, Hinabangan, Samar, from October 1998 to September 1999. Located within the former concession of Concord Mines Corporation, the site is accessible by either weapon/logging truck and by motorbike depending on the weather. Concord is about 70 km away from Catbalogan, the capital town of~Western Samar and 160 km from Tacloban City. However, before one can reach the experimental site, one has to bike about 7 km from Barangay Concord and cross four big rivers.
The site was under the existing and approved licensee of Mr. Maximino Teczon, who allowed FPRIDI to use the 36 selected experimental trees throughout the 12-month tapping schedule. After the study, all collected resins were turned over to the licensee as per agreement. The trees, which could be described as heavily tapped, each had about 2 to 4 open cuts or an average horizontal cut of 35 cm. They had a diameter at breast height (dbh) ranging from 38 to 110 cm and a total height of 40 to 95 meters. Three tapping lengths, viz., 10, 20 and 30 cm were studied, each length applied to 12 trees. The trees were sprayed with ethrel at four levels of concentration viz., 0, 0.5, 1.5 and 2.5%, each concentration having three replicates. This study followed the 3x4 factorial in completely randomized design (CRD). Factor A represented the three lengths of tapping cut and Factor B, the four levels of ethrel concentration. Each treatment combination was replicated thrice only owing to scarcity of healthy almaciga trees in the area.
Barks of almaciga trees were first cleaned using sharp bob and wood chisel. The three tapping lengths were applied one at a time to the 36 trees. Extra care was applied so as not to damage the cambium, a very thin region lying between the bark and the wood responsible for the formation of new phloem and xylem. The cambium is responsible for the regrowth of cut bark. Initial opening was placed uniformly for each of the three tapping lengths, at about ½ inch. On the other hand, the width of the subsequent rechipping was 5 mm or less and made above the former cut.
After cutting the streaks, ethrel at specified concentrations were immediately applied in a fine mist using the one-pint US standard plastic squeezer. Plastic bags were used as receptacles. Polyethylene plastic sheets were then attached to the trunk to cover the wounded portion. Sealed to each tree with plastic roofing cement. the sheets prevented seepage of water, dirt and other foreign bodies into the tacked plastic receptacles. Each tree was labeled.
Resins were collected weekly for a period of 1-year. The total resin yield at the end of the 12-month period was analyzed to determine the effect of tapping and ethrel concentrations. Rechipping was done after each collection and ethrel concentration applied. The amount of resin gathered was weighted and recorded.
The effect of seasonal variation on resin yield in relation to different tapping cuts and ethrel treatmnent was determined using the monthly rainfall data of the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) at its station in Catbalogan, Samar. The experiment site falls under the second climatic type, having no dry season but with a very pronounced maximum rain period from November to January.
The effect of tapping length on resin yield of almaciga is shown in Table I. The 30 cm tapping length gave the highest resin yield in the 12-month study period with 458.79 kg. This is 10.97% and 18.85% higher compared to 20 cm (411.92 kg) and 10 cm 372.32 kg) tapping lengths, respectively. The highest resin yield obtained from 30 cm tapping length maybe due to more resin ducts exposed and available for resin flow compared to 10 cm and 20 cm.
The effect of ethrel concentration on resin yield of almaciga is also shown in Table 1. In general, application of ethrel to tapped portion of almaciga trees increased resin yield. Further, resin yield was found to increase with ethrel concentration. Application of 2.5% ethrel concentration on tapped trees gave the highest resin yield of 425.03 kg, which is 51%, 42% and 16% higher than 0% (207.82 kg), 0.5% (248.02 kg) and 1.5% (362.15 kg) ethrel concentrations, respectively. Researches conducted by Abraham et al. (1969) and D'Ausac and Ribaillier (1969) as cited by Abeles (1973) on the potential of ethrel to increase rubber latex flow showed a two to four-fold increase in latex flow after ethrel application. The increase in the amount of latex collected was attributed to longer duration of flow. The ethylene in ethrel defers coagulation reaction in latex by preventing clotting thus, permitting longer latex flow (Leopold 1971 as cited by Abeles 1973). Since no studies on the effect of ethrel on exudation of almaciga resin were conducted prior to this study, the increase in resin yield after ethrel application may also be due to retardation of coagulation reaction of almaciga resin, and resin yield is further increased with ethrel concentration.
There was a significant interaction of tapping length and ethrel concentration on resin yield (Table 2). Almaciga trees with tapping length of 30 cm and 2.5% ethrel concentration produced the highest mean resin yield of 53,986.7 g. This was followed by trees with 20 cm tapping length and 2.5% ethrel concentration of 46, 090.0 g, while trees with tapping length of 10 cm and 0% ethrel concentration had the lowest with mean resin yield of 21,781.0 g (Table 3). Although, almaciga trees with tapping length of 10cm and 0% ethrel concentration produced the lowest resin yield, the mean resin yield was not significantly different from trees with 10 cm and 0.50%, 20 cm and 0%; 20 cm and 0.50%; and 30 cm and 0% tapping length and ethrel concentration. Likewise, mean resin yield of trees with 20 cm tapping length and 2.5% ethrel concentration was not significantly different with mean resin yield of trees with 30 cm and 1.5%; 20 cm and 2.5%; and 10cm and 2.5% tapping length and ethrel concentration (Table 3). The highest resin yield obtained in almaciga trees with tapping length of 30 cm and 2.5% ethrel concentration may be due to the combined effects of longer tapping length and higher ethrel concentration as explained above.
The effect of seasonal variation on resin yield was determined using monthly rainfall data obtained from PAGASA Station in Catbalogan, Samar (see Table 4). The total resin collected under the two rainfall periods amounted to 1,243.03 kg (Table 1), 69% of which was collected during the 8-month minimum rainfall period (February to September 1999) with an average monthly yield of 106.97 kg. The rest, with a monthly yield of 96.82 kg, was gathered during the maximum rainfall period (October to December 1998 and January 1999). Although rainfall directly affects aeration, moisture content, organic components and ion-exchange capacity of the soil (Kramer and Kozlowski 1960) the amount of rainfall did not seem to have a significant effect on resin yield of almaciga trees (Table 4).
The interactive effect of rainfall with ethrel concentration and tapping length on resin yield is shown in Tables 4 and 5, respectively. The relationship was analyzed using Pearson Correlation Coefficient.
There was a high inverse correlation of rainfall with 1.5% (r= - 0.644) and 2.5% (r= - 0.678) ethrel concentrations on resin yield of almaciga trees (Fig. I). However, this was not observed in 0% (r=0.529) and 0.5% (r0.072) ethrel concentrations. These results suggest that the effect of ethrel concentration on resin yield was not influenced by rainfall since no relationship was found in trees applied with 0% and 0.5% ethrel.
Figure 1. The interaction of rainfall and ethrel concentration on resin yield.
There was a significant correlation (inversely) of rainfall for tapping lengths 10 cm and 20 cm, but not in 30 cm on resin yield of almaciga trees (Fig. 2). This suggests that rainfall had effect only in trees with 10 cm and 20 cm tapping length. The increase in resin yield when almaciga trees were tapped for 10 cm and 20 cm lengths during the minimum rainfall period may be due to availability of more sunlight, which is important for resin production. Langenheim (2001, pers. comm.) observed that availability of more light than water had more effect on resin yield in leaves of Hymenaea and Copaifera seedlings. For 30 cm tapping length, rainfall did not have an effect on resin yield probably due to the effect of longer tapping length.
Figure 2. The interaction of rainfall and tapping length on resin yield.
Improved tapping techniques, e.g., the application of resin stimulants such as 2.5% ethrel, provided the almaciga tappers, traders and licensees in Samar and Palawan known as the major sources of high quality almaciga resin in the country, the necessary information on conserving almaciga stand and sustaining resin production. Through the years, the people practiced deep tapping, over-tapping and rechipping which killed many almaciga trees and endangered the industry that relies mostly on the supply of this resin.
Correct timing of rechipping will minimize the area of unwanted wounds on the trees. Table 6 shows the total height of tapping cut in each tree after a year. An average tapping height of 32 cm was attained with 53 cm as the maximum and 21 cm as the minimum. This was obtained after a 2-cm wide initial horizontal cut was made, and at least 3 to 5 mm cut thereafter per rechipping. Rechipping was done weekly throughout the entire study.
Properly timed rechipping prevents overlapping, prolonging the tree's life and sustaining resin production. Nevertheless, almaciga tappers may take sometime to adopt this procedure in some trees, since only little amount of resin exudes from a singled cut (applied in one thee/side) tree. This was observed in trees where previous cuts were too big and deep that lump of dried and bard resins are found just below the horizontal cuttings. Samar almaciga tappers have observed that resin yield per tree varies from 4-8 kg per harvest from multiple wounds, overtapping and deep tapping. The yield is normally collected after 21 days and occasionally after 1 to 2 months when considerable resin exudates have so1idified from the bark. In this regard, the collective annual resin yield of a tree can reach 45 kg of raw, unclean resin containing bark and other dirt particles.
Diameter was one of the original parameters of this study, but it was replaced by tapping length due to unavailability of trees with the needed diameter classes. Diameters were not reclassed in the revised schedule due to the big disparity of diameters among the 36 trees, viz., 38 cm dbh as the smallest and 110 cm dbh as the biggest.
Ethrel concentration was placed at 2.5% maximum. This level was somewhat in accordance with study conducted by Callano (1994) where latex stimulations with 2.5% ethephon, either at 10 or 4 applications per year lowers the latex's dry rubber content in all tapping systems studied. This first local application of ethephon in rubber trees indicated the possibility of applying ethylene as stimulant to resin producing trees like almaciga. The best and biggest yield of resin was found to be at 2.5% ethrel concentration followed in descending order by 1.5%; 0.5% and the control.
* Resin yield was found to be highest at 30 cm tapping length and 2.5% ethrel concentration Their interaction significantly influenced resin yield. Over the 12-month study, rainfall proved to have significant inverse relations on monthly resin yield for ethrel concentration of 1.5% and 2.5% and for tapping lengths 10 cm and 20 cm.
* Further experiments should be done using some of the previously used variables such as tapping length, diameter classes, crown ratio, other chemical stimulants preferably in paste form, and depth of tapping cut. The health of the almaciga trees, however, should be considered.
* Experiments should be done on trees that have never been tapped for resin production, i.e. almaciga plantation in Samar, to ensure better results of the study.
* Studies in the system of cleaning and grading of almaciga resin should also be given attention.
* Government and almaciga resin licenses should work band in hand to train tappers on improved collection methods, i.e. applying 25% ethrel solution at 30 cm tapping length; along with other scientific techniques.
* From observations and results of the study, workable guidelines for tapping almaciga trees have been developed for future implementation These are:
1) Tap only trees with at least 40 cm diameter at breast height.
2) Remove loose barks, dirt and other foreign materials and lightly serape the portion to be tapped. Start the first tapping at a point not more than 40 cm from the ground.
3) Make a horizontal cut of about 2 cm wide and 30cm long, and not beyond the bark, using a razor-sharp broad-bladed bob or a big knife,. Tapping more than twice around the tree circumference may be done, but the distance between tapped portions should be about 60 cm or twice the length of the cut. While cutting, take utmost care to avoid damaging the cambium.
4) Spray a mist of 2.5% ethrel solution about 6 inches away from the cut portion to stimulate resin flow. Apply one pass of 1-pint capacity plastic squeeze sprayer.
5) After a week when the resin exudation st6ps, a fresh cut may be made immediately above the previous one using the same length but lesser width (4 to 10 mm wide). Apply ethrel solution as before. Tap vertically upward and use a ladder if needed.
The authors wish to extend their grateful thanks to almaciga resin licensees who were also the principal cooperators of this study, Mr. And Mrs. Maximino Teczon and family for their cooperation and unselfish attitude to have shared their almaciga trees to serve as experimental trees; Foresters Pedro Calixto and Pedrito Torre, Department of Environment and Natural Resources (DENR) Regional Technical Director for Forestry, Region 8, Tacloban City and Community Environment and Natural Resources Officer CENRO) of Catbalogan, Samar, respectively, for their untiring effort and patience in guiding the crew who conducted the much needed ocular inspection and resource survey of healthy almaciga experimental trees, the activity required prior to project's implementation; Mr. Jose General, Sales Representative of Rhone-Poulenc Philippines Inc., for giving samples of ethrel solution; RDdrigo Pomarejos, the contractual laborer of the study for sharing his precious time as caretaker of the experiment and in data gathering; Mr. Enililo Raxna UT and flimily who shared their time for the interview on their tapping practices and flow of movement of almaciga resins, and also for their moral support and warm camaraderie extended throughout the duration of the study; Mr. Eduardo de la Cruz of PAG-ASA, Catbalogan, Station in Samar for providing the monthly rainfall data; and Ma. Socorro R. Dizon and Eleanor C. Jacinto of FPRDI for the statistical analysis.
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1 Scientist III (Study Leader), Science Research Specialist II and Science Research Specialist I, respectively, Forest Products Research and Development Institute (FPRDI), Department of Science and Technology (DOST), College, Laguna, Philippines.
1 Forest Products Research and Development Institute College, Laguna 4031 Philippines