Leaflet No.15/ 2016 The Republic of the Union of Myanmar Ministry of Natural Resources and Environmental Conservation Forest Department

Investigation on the Decay and Termite Resistance of Five Wood Species from Tanintharyi Region

Cho Cho Win, Assistant Research Officer Lwin Lwin Aung, Research Assistant- 2 Forest Research Institute, Yezin

December, 2016

Contents Pages

i

Abstract ii 1 Introduction 1 2 Literature Review 2 2.1. Thingan 2.2. Thingan-net 2 2.3. Kadut 2 2.4. Uban 2.5. Durability of Timber 3 3 Materials and Methods 3 3.1. Material 3 3.2. Sample Preparation 3 3.3. Laboratory Decay Test 4 3.4. Evaluation of Termite Test 4 3.5. Method of Analysis 5

4 Results and Discussion 6 4.1. Moisture content of tested species 6 4.2. Decay Resistance of Tested Species 6 4.3. Termite Resistance of Tested Species 8 4.4. Correlation between Specific Gravity and weight Loss 9

5 Conclusion and Recommendation 11 5.1. Conclusion 11 5.2. Recommendation 11

References 12

13

List of tables

Pages

Table 2.1 Durability Classification of Timber based on Weight Loss 3

Table 3.2 Visual Rating of timber for termite Resistance 5

Table 4.1 Moisture Content of Tested Species 6

Table 4.2 The Average Weight Loss of Tested Species against White 7 Rot Fungus

Table 4.3 Visual Rating and weight Losses of Tested Species against 8 Termite

Table 4.4 Correlation between Specific Gravity and Weight Loss by 10 Termite

List of Figures

Figure 4.1 Decay Resistance of Tested Species 7

Figure 4.2 Termite Resistance of Tested Species 9

Figure 4.3 Correlation between Specific Gravity and Weight Loss by 10 Termite

၊ ၊ -၂

(H. helferi Band)၊ (HopeaodorataRoxb)၊ (Shoreacinera CEC Fischer)၊ (Shoreafarinosa CEC Fischer)၊ (Shoreasericiflora) ။ ၏ Agar Block ။ Agar (၁၆)

။ (under- ground method) ။ ၏ (၅) ၀.၂၁၉% ။ ၂.၃၈၅% ။ ၊ ၊ ၊ (၃) ။

။ (၃) ။

Investigation on the Decay and Termite Resistance of Five Wood Species from Tanintharyi Region

Cho Cho Win (Assistant Research Officer) Lwin Lwin Aung (Research Assistant-2)

Abstract

Dipterocarpaceae is one of the important timber families were largely exploited for their timber in the past. In this study, we performed laboratory evaluations of selected five wood species namely, Thingan-net (H. helferi Band), Thingan (HopeaodorataRoxb), Kadut (Shoreacinera CEC Fischer), Uban (Shoreafarinosa CEC Fischer) and Kaban-thangyin (Shoreasericiflora) from Tanintharyi Region. The objective of this study is to study the natural durability of tested species. The laboratory test of the relative decay resistance was carried out using Agar-block test in this research. The resistance on subterranean termites of tested wood samples was conducted using the visual rating and weight losses of tested species after four months exposure in ground. According to the results, it was found that the average weight loss in dry weight percent of Thingan-net is 0.219% and it is Very Durable, and that of Thingan is 2.385% and it is Durable species. That of Kadut, Uban and Kaban-Thangyin are 5.632, 7.224 and 5.986 respectively and they are moderately durable class. Among the tested species, two Hopea species (Hopeahelferi and Hopeaodorata) were found to be comparable with Teak in termite resistance. In the case of Shorea species were found to be slightly attack by Termite.

Key words: Natural Durability, Decay Resistance, Termite Resistance, Hopea spp., Shorea spp.

Investigation on the Decay and Termite Resistance of Five Wood Species from Tanintharyi Region

1. Introduction

Dipterocarpaceae is one of the main timber families in the forests of Southeast Asia that forms a high proportion of the emergent and main canopy strata of the forest (Manokan, 1996). The members of this family, besides playing a vital role as potential timber species that form an important means of economy in the timber market (Appanah, 1998; Poore, 1989) also act as source of other non-timber products for the livelihood of the forest dwellers (Panayota & Ashton, 1992). From the oleoresins of Dipterocarpus alatus and Dipterocarpus grandiflorus, Gurjan oil is produced which is used as medicine to treat various skin ailments and ulcers. The resins also have industrial application as varnish and anti-corrosive coatings. The hard solid resin, commonly called as rock dammar, derived from Hopea species is used for making boats and handicrafts (Shiva&Jantan, 1998). Dipterocarpus includes about 19 genera and 380 species of trees or rarely shrubs and among them 70 species of large trees widely scattered through the Indo-Malayan region. Shorea is a genus of about 196 species of mainly rainforest trees in the family Dipterocarpaceae. Many economically important timber trees belong to the genus, sold under names including "meranti", "lauan", "luan", "lawaan", "seraya", "balau", "bangkirai" and "Philippine mahogany". Dipterocarps are observed mostly on the low altitudinal zones (Whitemore, 1988) and the number of individuals and species decreases with increasing altitude (Devraj, 2001). In Myanmar, there are 24 species under Dipterocarpaceae family (Appandix). Tanintharyi Region in Myanmar is almost covered by tropical rain forest in high elevation mountain sites, but the forest is associated with mixed deciduous and bamboo forest in the lowlands. There are altogether 258 species found in the Flora Survey of TNR of which 5 critically endangered species and 5 endangered species are recorded. List of critically endangered and endangered species are found to be mostly of Dipterocarp species (Hla Maung Thein, 2007). The canopy layer is occupied by evergreen tree species with the height ranging from 40-60 m (including Hopea odorata Roxb.)(GIS section, 2007). Dipterocarp forests in general, and Hopea odorata forests in particular, are now seriously depleted due to heavy exploitation and degradation of habitats by people and concessions. Widespread utilization of wood and ever increasing export markets will eventually call for proper utilization of lesser used timber species. Effective utilization of wood depends on strength, durability, beauty and availability of a species. There have no updated data on durability of some timber species under Dipterocarpaceae family. In the present research, we performed laboratory evaluations of selected five wood species (primarily heartwood, since sapwood rarely resists termite or decay) from Tanintharyi region using standard laboratory method for fungus resistant testing and termite resistant testing.

The objectives of this study is • To study the natural durability of five wood species from Tanintharyi Region by evaluation of resistance to decay and termite tests. • From the results obtained, to suggest how these test species could be used for various end uses. 2. Literature Review

2.1.Hopea odorata Roxb. (Thingan)

It was distributed from Bangladesh into Indochina and Peninsular Malaysia, (Myanmar), India (Andamans), Indochina, Malaysia (North Peninsula), Thailand, Laos (Khammouan). It is a large tree reaching up to 45 m in height with the base of the trunk reaching a diameter of 4.5 m (including buttresses). It was found often gregariously along river banks, up to 600 m elevation. The sapwood is pale yellow or grayish yellow turning pale brown on exposure, heartwood yellowish-brown to brownish red sometimes with dark streaks, turning purplish on exposure, with lustrous white resin canals at irregular intervals, becoming dull with age. Thewood is very hard and heavy weighing 755-kg/cu m, difficult to saw but finishes well. Durable timber used for shipbuilding and houses. It is chiefly used for boat-building, dug-out canoes and for construction purposes, where durability and strength are of primary importance. It is also used for carts, presses flooring, roofing, piles, fence-posts, ploughs, furniture, etc. It is a first class sleeper wood.

2.2. Hopea helferi Brandis (Thingan net)

It is a critically endangered species of in the Dipterocarpaceae family. It is found in , the Andaman Islands of India, Peninsular Malaysia, Myanmar, and Thailand. Synonyms are Hopea dealbata Hance, Shorea helferi (Dyer) Kurz, Vatica helferi Dyer. Hopea helferi is a medium-sized to large evergreen tree usually growing 20-37 meters tall.

2.3. Shorea cinerea C.E.C.Fisch., (Kadut)

It is a evergreen tree of 24-40m height. It is found in Malaysia, Myanmar, Thailand, and . Synonyms are Parashorea stellata Slooten 1927, non Kurz 1870, Shorea stellata (Kurz) Dyer and also called White Seraya. It was distributed in mixed and open degraded forests on poor soil from 300 - 800 m altitude. It is threatened by habitat loss. (Ashton, P. 1998).

2.4. Shorea farinosaC.E.C.Fisch (Uban)

Shorea farinosa is a tree in the Dipterocarpaceae family. It grows some 30-45m tall while its trunk may reach 2m in circumference; it occurs in the dense forests of the plains of southern Myanmar, Thailand and Cambodia, while it is cultivated in Vietnam. The wood is in demand for use in construction ( DY PHON Pauline, 2000). It is called as Kyauk –thingan, Thingan –phyu.

2.5. Durability of Timber

It is important to note that natural durability refers only to mature outer heartwood. Sapwood of all timbers is considered non durable. The heartwood of all timbers can be classified according to its natural durability (or resistance) against attack by wood destroying organisms such as termites, borers and decay fungi. The resistance is due to the presence of special tannins, oils, resins and extractives in the heartwood that repel or kill insects and decay. It is usual to classify timber into five classes with respect to their natural durability. In the following table, the corresponding life of 2"x2"x2" stakes in average soil was compared with average loss in dry weight percent of wood specimens caused by one of the selected decay fungi in laboratory tests.

Table.2.1. Durability Classification of Timber based on Weight Loss Life of Test Stake in the field Average loss in dry Durability Class England Tropics weight (%) Very Durable Over 25 yr. Over 10 yr. Nil- or negligible Durable 15 - 20 yr. 5 -10 yr. Up to 5% Moderately Durable 10 - 15yr (not given) 5-10% Non-Durable 5- 10 yr. 2 - 5 yr. 10-30% Perishable Less than 5 yr. Less than 2yr Over 30%

Source: W. P. K. Findlay (1985)

3. Materials and Methods 3.1. Materials

In this study, among the Dipterocarpaceae family from Tanintharyi Region, two Hopea spp and three Shorea spp were studied. The tested species were:-

Thingan-net (Hopea helferi Band) Thingan (Hopea odorataRoxb) Kadut (Shorea cinera CEC Fischer) Uban (Shorea farinosa CEC Fischer) Kaban-thangyin (Shorea sericiflora)

The tested species were collected from Ye Phyu Township in Tanintharyi Region. Only one tree was collected for each species. The wood samples were authenticated at Herbarium and Anatomy Section of Forest Research Institute (FRI), Yezin. Only the heartwoods were tested.

3.2.Sample Preparation

Sample preparation was carried out at Saw-mill of FRI. For decay test, (12.5mm x 12.5mm x 25mm) blocks and for termite resistance evaluations, (20mmx20mmx20mm) blocks were prepared. Fifteen replications were prepared for each test. These boards were free from knots, drying defects and without visible evidence of fungus infection.

3.3. Laboratory Decay Test

In order to provide rapid evaluation of the relative durability of species, laboratory tests of the relative decay resistance was carried out. Agar-block test was used in this research. The white rot fungi (Coriolus versicolor) were used in this study since these fungi are common to hardwood. The fungi specimen was cultured on Potatoes- Dextrose Agar (PDA) media. The procedure taken for the fungus culturing was as follows:- a) 200g of peeled, diced potatoes, 20 g of dextrose and 15 g of agar were dissolved with 1000 ml of distilled water in a flask and heated till boil. b) The media was distributed into the test tubes, approximately 20 ml in each tube. c) The test tubes were plugged with cotton and sterilized in autoclave sterilizer for 20 minutes at 105 ˚C and 15 psi pressure. It was necessary to sterilize the media before using in order to kill bacteria or fungal spores which will possibly present in the media or in the glassware. d) The test tubes were taken out from the autoclave sterilizer and cooled to room temperature. e) The fungus inoculums were cut and placed on the media. After 3 to 5 days, the fungus grew well, with mycelium. These were ready for decay test. f) Each test sample block was weighed and it was designated as initial weight (I. Wt). g) After that, all the test samples were exposed to fungal attack by placing them over the fungus mycelium in the test tubes. Tiny chips of glass- rod were placed between bamboo samples and the fungus in order to prevent the direct contact between them. h) The test tube were placed at ordinary room temperature and incubated for 16 weeks. i) After completion of the incubation period, the test blocks were taken out and attached mycelium was carefully cleaned. j) The test blocks were oven dried at 103 ± 2° C until the constant weights were obtained and then, the oven-dry weights were recorded as final oven dry weight (FOD Wt) to calculate the weight loss percentages of the test blocks.

3.4.Evaluation of Termite Resistance

In the tropics, termites, particularly the subterranean species, poses a serious threat to timbers. The accelerated laboratory test was used. The test blocks (20mm x 20mm x20 mm) were oven dried at 60 °C overnight and weighed. The weights were recorded as initial weight W1. A test site at FRI, highly susceptible to subterranean termites was chosen for study. The design of the field test procedure is as follows: a ditch of consistently 15-20 cm depth is dug to partly layer with residues from coconut fibers and susceptible wood veneers (to bait and aggregate termites). Wood blocks were then placed about this depth above the residue layer and additional amounts of residues added to conceal the blocks, and the ground covered with top soil. The blocks (5 replications) were kept together according to species to aid identification of the specimens at the end of test. After 16 weeks, the specimens were removed from the tested sites and cleaned up. The ground was unearthed, the blocks carefully retrieved, weighed immediately to determine the final wet weight and then oven dried at 60°C in oven by the same way of determination of initial mass and the final oven dry weight was marked as W2. The test blocks were also rated according to an arbitrary 0-5 visual scale as: 0 = sound, l = surface, 2= light attack, 3= moderate attack with bore holes, 4= heavy/severe attack and 5= completely destroyed. The grading of termite resistance was estimated by mass loss of specimen and visual observation. The grading by mass loss of specimen was corrected by visual observation according to table (3.1).

Table 3.2.Visual rating for termite resistance

Visual Rating Rate No attack (sound) 0 Surface attack 1 Slightly attack 2 Moderately attack 3 Severe attack 4 (completely destroyed) 5

Source: American Wood Preservers’ Association (AWPA) Rating

3.5.Method of Analysis

To estimate the calculated oven dry weight of each test block, the average initial moisture content (MC) of the MC-samples was used. The MC of the samples was determined by using oven-dry method.  The initial weight of each moisture content sample at air -dry condition was weighed and recorded as initial weight.  After that, the samples were oven-dried at 103 ± 2° C to obtain the constant weight and the oven dried samples were weighed and recorded.  The M.C of each samples at air dry and green conditions were calculated by using the following equation.

I.wt - O.D wt MC (%) = wWt x 100 O.D wt where, M.C = moisture content of the sample I.wt = initial weight of the sample O.D.wt = Oven Dry weight of the sample

Then, average initial MCs of MC-blocks were calculated based on the average initial air- dry M.C. The calculated oven dry weight of each test sample for vacuum-pressure treatment was calculated by using the following formula. I. wt x 100 C.O.D.wt = (100 + M.C %) where, C.O.D.wt =calculated oven dry weight of the sample

To determine the weight loss percent of each of the test samples the following formula was used.

(C.O.D .wt - F.O.D wt) Wt. Loss (%) = X 100 C.O.D. wt where, C.O.D wt = calculated oven dry weight F.O.D wt = final oven dry weight

4. Results and Discussion 4.1.Moisture content of tested species

The average moisture content of tested species is shown in table 4.1. According to this table, the mean moisture content of Thingan-net is 39.03% and the minimum and maximum moisture contents are 35.93% and 40.56%. Thingan has a mean moisture content of 29.03% andthe minimum and maximum moisture contents are24.38% and 32.67%. Mean moisture content of Kadut is 39.8%. Its minimum and maximum moisture contents are 32.12% and 49.23%. The mean moisture content of Uban is 60.32%. Its minimum and maximum moisture contents are 45.79% and 88.72%. The mean moisture content of Kaban-thangyin is 69.16%. The minimum and maximum moisture contents are 55.92% and 79.14% respectively. Table 4.1: Moisture content of tested species

Sr. Moisture content (%) Species No. Mean Minimum Maximum Standard deviation 1 Thingan- net 39.03 35.93 40.56 1.34 2 Thingan 29.03 24.38 32.67 2.09 3 Kadut 39.80 32.12 49.23 5.10 4 Uban 60.32 45.79 88.72 17.75 5 Kaban-thangyin 69.16 55.92 79.14 8.81

4.2. Decay Resistance of Tested Species

Results of the experiments were evaluated as mean weight loss percent of individual species. The average weight loss in dry weight percent of Tested Species were shown in table (4.2). According to the Natural Durability Classification (Findlay, 1958), the natural durability of the tested species are also given in Table (4.2).

Table (4.2) The average weight losses in Tested Species by fungus

Weight Loss (%) Species Durability Class Minimum Maximum Mean SD Thingan-net -1.766 0.587 0.219 0.643 Very Durable Thingan 1.235 3.449 2.385 0.69 Durable Kadut 0.559 8.702 5.632 2.38 Moderately Durable Uban 0.880 12.558 7.224 4.04 Moderately Durable Kaban-thangyin 1.587 8.101 5.986 1.88 Moderately Durable

According to this table, it was found that the average weight loss in dry weight percent of Thingan net (Hopea helferi Band) is 0.219%. Therefore, it lies in Very Durable class, Durability Class I. That of Thingan (Hopea odorataRoxb) is 2.385 and it lies in Durable class. In the case of Kadut (Shorea cinera CEC Fischer), Uban (Shorea farinosa CEC Fischer) and Kaban-thangyin (Shorea sericiflora) it was found that the weight losses by decay fungi were 5.632, 7.224 and 5.986 respectively and they lie in Moderately Durable class. The decay resistance of tested species was shown in figure 4.1. It can be seen clearly that Thingan net was the lowest in weight losses among the tested species.

Decay Resistance of Tested Species

10

5

0 Weight Loss (%) Loss Weight

Species

Figure 4.1. Decay Resistance of Tested Species As I mentioned earlier, the Shorea species are well known in the market trade name as “meranti", "lauan", "luan", "lawaan", "seraya", "balau", "bangkirai" and "Philippine mahogany. The standard graveyard tests on untreated specimens carried out by the Forest Research Institute Malaysia (FRIM) have classified dark red meranti as moderately durable with an average service life ranging from about 2.0 years (S. singkawang) to 3.9 years (S. platyclados). For the species S. curtisii, S. pauciflora, S. platycladosand S. acuminata, the heartwood is classified as moderately durable (with an average service life of 2-5 years). Similar tests on S. paucifloraat Princess Risborough (U.K.) have indicated that the timber is moderately durable with a service life of 10- 15 years (under temperate conditions).

4.3. Termite Resistance of Tested Species

The resistance on subterranean termites of tested wood samples wasshown in Table (4.3). The visual rating of test samples and weight losses are also presented in this table.

Table (4.3) The Visual Rating and average weight losses of Tested Species

Visual Wt Loss (%) Durability Species rating Minimum Maximum Mean SD Class Teak 0 0.51 1.59 1.18 0.37 Resistant Pine 5 18.571 45.623 33.202 6.818 Severe Attack Thingan-net 0 -1.766 0.587 -0.219 0.643 Resistant Thingan 0 -1.28 4.88 0.919 1.94 Resistant Kadut 3 0.67 9.378 5.543 3.397 Moderately Attack Uban 2 -3.187 18.48 4.499 6.095 Slightly Attack Kaban-thangyin 3 0.214 9.21 5.359 1.645 Moderately Attack

According to this table, it can be seen that visual rating of Thingan-net is Zero and weight loss percentage of it is found to be -0.219. Therefore, Thingan-net is found to be termite resistant in the same class as teak from the two sources, while the same result was found for Thingan (visual rating: 0, weight loss: 0.919) and it is to be termite resistant. For Uban, the visual rating lies in 2 and the average weight loss is found to be 4.499. So, it is slightly attack by termite. In the case of Kadut and Kaban – thangyin (Visual rating: 3 and weight losses: 5.543 and 5.359 respectively), they are found to be moderately attack by termite. The termite resistance of Hopea species were found to be comparable with Teak, the best resistant to termite. In the case of Shorea species were found to be slightly attack by Termite but termite resistant of the Shorea species were better than that of Pine (Pinusinsularis), where all the replicate blocks of the latter were completely consumed after four months (visual rating: 5, weight loss (%): 33.3). According to the results, it can be said that Thingan –net is very durable and it can last over 25 years in temperate regions and over 10 years in tropics. As for Thingan, it can last 15 to 20 years in temperate regions and 5 to 10 years in tropics. Therefore, these species can be used with confidence for permanent structures in contact with the ground or in water in the aspect of durability. It can be chiefly used for boat-building, bridge building and for construction purposes, where durability and strength are of primary importance. The moderately durable species: Kadut, U-ban and Kaban-thangyin can last 10 to 15 years in temperate and over 5 years in the tropics. However, wood in this class should never be used in direct contact with the soil unless given preservative treatment. They are suitable for those parts of permanent structures that are given protection against weather eg. Rafters and joints. Mean weight losses against termites are shown graphically in figure 4.2.

Termite Resistance of Test Species

6

5

4 3 2

1 Weight Loss (%) 0 Thingan-net Thingan Kadut Uban Kaban-thangyin -1 Species

Figure 4.2.Termite Resistance of Tested Species.

In comparison with other Shorea species in termite resistance, Yellow meranti is resistant but all other types of meranti are not resistant. The sapwood of dark red merantiis susceptible to dry-wood termite attacks, which may eventually spread to the heartwood. However, an initial invasion of the heartwood is less likely to occur. According to above-ground method, Balau (other than red Balau) is durability class 1 - life expectancy over 40 years. Red balau is class (4) - life expectancy less than 7 years. Philippine mahogany (light red) is class (4) - life expectancy less than 7 years. Philippine mahogany (red) is class 3 - life expectancy 7 to 15 years. Meranti (dark red) class 3 - life expectancy 7 to 15 years. Meranti (light red) class 4 - life expectancy less than 7 years. Meranti (white) is class (4) - life expectancy less than 7 years and Meranti (yellow) is class (4) - life expectancy less than 7 years. According to in-ground method, the durability of Balau (other than red Balau) is class 2 - life expectancy 15 to 25 years. Red balau class 4 - life expectancy less than 5 years. Philippine mahogany (light red) class 4 - life expectancy less than 5 years. Philippine mahogany (red) class 4 - life expectancy less than 5 years. Meranti (dark red) class 4 - life expectancy less than 5 years. Meranti (light red) class 4 - life expectancy less than 5 years. Meranti (white) class 4 - life expectancy less than 5 years. Meranti (yellow) class 4 - life expectancy less than 5 years.

4.4. Correlation between weight loss and specific gravity

Many heavy woods are highly durable. This may suggest that the density of wood, i.e., its weight per unit volume may be criterion of decay resistance. Generally, high density timbers are more durable than lighter ones. In table 4.4 showed the correlation between specific gravity and weight loss of tested wood species were made using simple linear correlation. According to Table 4.4, it can be found that Thingan-net has the highest specific gravity and it can give the lowest weight loss and Uban has the least specific gravity and it has the largest weight loss among tested species. Therefore, there was a highly correlated between specific gravity and weight loss of tested wood species.

Table (4.4) The Correlation between Specific Gravity and Weight Losses of Tested Species

Sr. No. Species Sp. Gr.* Weight loss 1 Thingan- net 0.922* 0.219 2 Thingan 0.684* 2.385 3 Kadut 0.561* 5.632 4 Uban 0.422* 7.224 5 Kaban-thangyin 0.598* 5.986 *Win oo Naing et al (2016) unpublished.

Correlation between sp.gr and weight loss 8 Uban 7 Kaban-thangyin 6 Kadut 5

4

3 y = -14.959x + 13.824

Weight Loss(%) Thingan R² = 0.9152 2

1 Thingan-net 0 0.00 0.20 0.40 0.60 0.80 1.00 Specific gravity

Figure 4.3. Correlation between Specific Gravity and Weight Loss

According to Figure 4.3, it can easily be seen that there was a negatively correlated between specific gravity and weight loss of tested wood species according to the equation of y = - 14.95x + 13.82, that means the larger the specific gravity value, the lower the weight loss. However, it was noted that a number of light woods, such as redwood, cedars, or catalpa are among the most durable. On the other hand, the heartwood of relatively heavy woods, such as beech, red and black oak and maple is among the least decay resistant woods. This is because there is no significant difference in decay resistance of the extractive free wood substance. The superior durability of some woods including those of light density is directly to the presence of toxic ingredients in sufficient quantities to inhibit deterioration (Panshin, A. J & De Zeeuw, C, 1980).

5. Conclusion and Recommendation 5.1. Conclusion

1. The average weight loss in dry weight percent of Thingan-net is 0.219% and it is Very Durable, durability Class I. 2. The average weight loss in dry weight percent of Thingan is2.385% and it lies in Durable Class (Class II). 3. The average weight loss in dry weight percent of Kadut, Uban and Kaban-Thangyin are 5.632, 7.224 and 5.986 respectively and they are moderately durable class (Class III). 4. It can be concluded that the Hopea species of tested Dipterocarpus are resistant to fungus (white rot fungus) attack. The Shorea species of tested Dipterocarpus are moderately resistant to white rot fungus attack. 5. Among the tested species, two Hopea species (Hopeahelferi and Hopeaodorata) were found to be comparable with Teak in termite resistance. In the case of Shorea species were found to be slightly attack by Termite. 6. There was a negatively correlated between specific gravity and weight loss of tested wood species according to the equation of y = - 14.95x + 13.82

5.2. Recommendation

In Myanmar, There are totally 50 threatened plant species, of which 18 critically endangered, 16 Endangered and 16 Vulnerable based on the classification from IUCN Red List. It indicates that Dipterocarpaceae is the most threatened plant family with 16 Critically endangered species, 7 Endangered species and 2 Vulnerable species out of 19 threatened plant families (Internet). According to Ashton, P. (1998), Hopea helferi and Hopea odorata forests in particular, are now seriously depleted due to heavy exploitation and degradation of habitats by people and concessions and they are IUCN Red List of Threatened Species. In Taninthayi Region where extensive commercial plantation concessions for palm oil have been established, plant species from the Dipterocarpaceae, families have been highly threatened by habitat loss, degradation and fragmentation. Therefore, it was highly recommended that conservation of such threatened plant species should be prioritized in Taninthayi Region.

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Van Steenis, C.G.G.J. 1948. Flora Malesiana. Flora Malesiana Foundation, Leiden. Whitmore, T.C. 1990. Comments on draft listing of tropical timbers of Peninsular Malaysia. နောက်ဆက်တွဲ ( )

Dipterocarpaceae ၀ ( )

၁။ Dipterocarpus baudii Korth. Gurjan (Timber ) ၂။ Dipterocarpus turbinatus Gaetn. Wood oil ၃။ Dipterocarpus grandiflorus Blanco. Yang-Yung ၄။ Dipterocarpus alatus Roxb. Wood oil (Garjian) ၅။ Vaticadyeripierre ex Laness./ Resakbiabas Vaticagrandiflora Dyer / Vaticafaginea (French ) Dyer ၆။ Dipterocarpus costatus C. F. Gaertn. Deng-Yang (French ) ၇။ Shorea argentea ၈။ Shorea floribunda ၉။ Shorea sericiflora ၁၀။ AnisopteracostataKorth ./ AnisopteraoblongaMersawa ၁၁။ Anisopterascaphula ၁၂။ ( : ) Shorea assamica Dyer. White meranti ၁၃။ Vaticalanceaefolia, Grape myrtle Indian lilae ၁၄။ VaticaodorataGriff. Symington Damarbatu ၁၅။ SorearobustaGaertn. f. Sal tree ၁၆။ ParashoraStellataKurz. White seraya; ၁၇။ Hopea odorata Roxb. Rock dammar tree ၁၈။ Hopea hilferi ၁၉။ Hopea minutifolia ၂၀။ Shorea obtuse Wall./ Shorea Taengwoodbalau oblongifolia ၂၁။ Dipterocarpus tuberculatus Roxb. Enggurjun tree ၂၂။ Vateriaindica L. White Damar ၂၃။ ( ) Dipterocarpus obtusifolius Hieng ၂၄။ ( ) Shorea gratissima Dyer /S. farinosa Five - Winged nut