Thai Journal of Forestry

Recreational Value of Sakunothayan Botanical Garden, Phitsanulok Province

Supatchaya Wechvitan — 2023-12-14

The objectives of the study were to determine the socio-economy characteristics, general information on recreation of visitors and evaluation of the recreational value of the Sakunothayan Botanical Garden, Phitsanulok province. The estimations were done by using individual travel cost method (ITCM) and contingent valuation method by willingness to pay (WTP). Data were collected by interviewing 398 visitors who traveled to the Botanical Garden during January to April 2022.

The results indicated that a majority of visitors were male with an average age of 32.68 years. Most visitors had an undergraduate degree with their occupation primarily being personal business /trade with an average income of 16,414.82 Baht/month. Most of the visitors had visited the Sakunothayan Botanical Garden an average of 4.28 times and came for recreation with their families of an average size of 4 persons. The average distance from the accommodation to Sakunothayan Botanical Garden is 71.39 km, with most of the visitors using their personal vehicles. The average travel expenses were 227.58 Baht, and the average level of satisfaction was high.

The recreational value of the Sakunothayan Botanical Garden, as calculated by the ITCM was 11,658,634.90 Baht/year, while that estimated using the contingent valuation method by WTP was 1,188,832.08 Baht/year. This study can be used during the budgetary allocation planning for resource maintenance, area and facility management and can also be used as a criterion for determining the appropriate service fee that can be levied for the Sakunothayan Botanical Garden.

Forecasting the Carbon Sequestration of System of Intensive Forestation at the Wang Chan Forest Learning Center, Rayong Province

Areerat Sieosathanakul — 2023-12-14

The research objective was to determine the tree carbon storage and to generate the forecasting carbon sequestration in the next five years of forest planted by System of Intensive Forestation (SIF) at the Wang Chan Forest Learning Center, Rayong Province. Data collection was done from permanent sample plots of size 40x40 m² base on stratified random sampling method by density of trees namely high, medium and low, with one plot per stratum. The data recorded were the tree species, respective diameters, and the total height of every tree in the permanent sample plots from 2015–2022 anuanly. The biomass was estimated using allometric equation specified for dry evergreen forests and the carbon sequestered was quantified by following the methodology of Intergovernmental Panel on Climate Change (IPCC) 2006. The regression equations were used to forecast the carbon dioxide that would be sequestered in the next five years.

We found 64 tree species, 58 genus, and 33 families. The highest tree density was of Dalbergia cochinchinensis, with Pterocarpus macrocarpus and Lagerstroemia floribunda having the next highest densities, of 19.58, 11.13 and 10.54 tree/rai (122.38, 69.56 and 65.88 tree/ha), respectively, with a biomass of 10.21 ton/rai (63.81 ton/ha). The carbon sequestered for 8 years was estimated at 4.80 tonC/rai (30.00 tonC/ha), while the carbon dioxide sequestered was 17.60 tonCO₂/rai (110.00 tonCO₂/ha), with a increment rate of 2.20 tonCO₂/rai/year (13.75 tonCO₂/ha/year). The regression equation forecasted the amount of carbon dioxide sequestered within the next five years (2023–2027) was of the form; carbon dioxide sequestration = -4.72+(2.63*Year), R² = 0.93. Using this equation, the carbon sequestration of 2023–2027 were 18.95, 21.58, 24.21, 26.84 and 29.47 tonCO₂/rai (118.43, 134.87, 151.31, 167.75 and 184.18 tonCO₂/ha, respectively.

Characterization of Rainfall in the Upper Mae Sa Watershed, Mae Rim District, Chiang Mai Province

Suthasinee Petchhan — 2023-12-14

Rainfall characteristics are essential for a watershed and its water resource management. Results can vary depending on the method and the number of stations used for analyzing the areal rainfall. The objective of this study was to compare the rainfall characteristics including number of storm and days, duration, intensity, and the amount as indicated by different methods. The methods used to calculate the various characteristics were Thiessen polygon (TP) based on observed data from 11 stations and arithmetic mean (AM) based on observed data from 11, 5, 3 and 1 station(s). Data were measured from 2005 to 2012 using automatic recording rain gauges. Using TP, the results indicated that the variation in the daily number of storms calculated using one station was different stations. Monthly, mean monthly, and annual variations in the daily number of storms were not different. The rainfall intensity and duration estimated using different methods and the number of stations were not similar. The daily, monthly, and mean monthly number of rainy days were not different while the annual variation calculated using AM on data measured from three stations and a downstream station were not the same. The daily rainfall amount calculated using one station was different from that estimated using TP, while the monthly, mean monthly, and annual changes were not different. We conclude that to characterize the rainfall in a given area, the appropriate number of rainfall stations should not be less than three, which should be located at different elevations at the upper, middle, and downstream area of a watershed.

Potential of Giant Reed Fiber (Arundo donax L.) in Thailand for the Kraft Paper Industries

Thitima Laohasinnarong — 2023-12-20

We studied the potential of giant reed fiber (Arundo donax L.) in the kraft paper industries, with the primary focus on the basic properties of the raw material. An analysis of the chemical composition and fiber morphology was conducted. The pulp of giant reed kraft was prepared in 20 to 25% active alkali, having 30% sulfidity, at a maximum temperature of 170^oC for 60 minutes. Subsequently, the pulp yield and kappa number were measured for evaluating the optimum potential as an alternative to the industrial kraft pulp. The results indicated that its chemical composition contained 74.88% holocellulose, 41.26% cellulose, 22.42% lignin, 24.59% pentosan, 10.22% extractive, and 4.46% ash. The fiber morphology had a slender fiber shape with a length and width of 1.45 mm and 24.01 micron, respectively. The measured pulp yield, residue, and kappa number were 51.54%, 1.30% and 25.2, respectively. It was observed that the giant reed kraft pulp had a higher potential than some non-wood and wood kraft pulps e.g., bagasse, eucalyptus, and softwood. The various pulps were beaten to 350+20 ml (Canadian Standard Freeness: CSF) freeness and the pulp handsheets were prepared for strength testing. It was observed that tensile index, tear index, burst index, and folding endurance of the giant reed pulp were higher than bagasse and eucalyptus but lower than softwood. We conclude that the giant reed can be considered as a viable raw material option in the kraft paper industry.

A Study of Change in Forest Area during 2013-2022 in the Sri Lanna National Park, Chiang Mai Province

Alongkot Pakat — 2023-12-20

The objective of this study was to apply remote sensing techniques to examine the changes in the forested area around the Sri Lanna National Park during a period of 10 years from 2013–2022, using computer-based classification of Landsat 8 OLI satellite data. Supervised classification techniques were used in conjunction with visual interpretation, which included the use of GIS (geographic information system) to assist in data management. At least 500 inspection points were used around the Sri Lanna National Park to determine the accuracy of the classification by using an error matrix or confusion matrix table and Kappa statistics.

Using the classification, it was observed that the forested area decreased by 4,439 rai (710.24 ha) between 2013–2022, with the most decrease experienced during the past 10 years. Specifically, between 2014–2015, the area decreased by 1,308 rai (209.28 ha), 2015–2016 decreased by 605 rai (96.80 ha), 2016–2017 decreased by 1,988 rai (318.08 ha), 2017–2018 decreased by 863 rai (138.08 ha), 2018–2019 decreased by 297 rai (47.52 ha), in 2019–2020 decreased by 353 rai (57.28 ha), in 2020–2021 decreased by 386 rai (61.76 ha), and in 2021–2022 decreased by 153 rai (24.48 ha), was the least decrease during the 10 years analyzed. The classification accuracy for each year indicated to an average overall accuracy of about 85.54 percent and a Kappa statistic of 77.74 percent. The trend of change in the forested areas was a polynomial of the 3^rd order as described by the equation y = -0.0322x³+ 195.19x² - 394313x + 3E+08 (R² = 0.9789), where x is the year of interest.

Spatial Interpolation of Regional Rainfall Data of Thailand Using Different Methods

Usawan Upakhot — 2023-12-20

Distributed areal rainfall is important data for hydrological modeling. Spatial interpolation is used to predict the values of a continuous variable at unmeasured points. This study compared the distribution and prediction error in the spatial interpolation maps of rainfall derived from different methods. Inverse Distance Weighted (IDW) using a power (p) equal to 2 and 3, and number of neighbor point (n) equal to 15, 30, and 50 points point and Kriging Ordinary (KrigOrd) with Circular, Exponential, Gaussian, Linear, and Spherical model were used and their predictions compared. Cohen’s kappa coefficient and mean absolute error were used to compare distribution and error in spatial interpolation, respectively. The results indicated that the distribution and parameters obtained from different spatial interpolation methods were in good agreement as indicated by k values (0.9202 to 0.9999) but results of IDW predicted a gradual change, while that from KrigOrd had localized features and abrupt change. The lowest spatial interpolation error from measurements in the north, northeast, central, east and south (east coast) parts was obtained for IDW with p of 2 with differing number of neighbors equal to 15, 15, 50, 50, and 15 points respectively, while that for the south (west coast) was obtained using the KrigOrd with a linear setup. Mean absolute error (MAE) for each method was 133.88 132.49 114.83 184.01 181.54, and 142.52 millimeters or 11.30, 10.25, 10.58, 11.76, 10.90, and 5.44 percent of the mean annual rainfall, respectively.

On the Habitat of Siamese crocodiles (Crocodylus siamensis) in Phetchaburi River, Kaeng Krachan National Park, Phetchaburi Province, Western Thailand

Kasidis CHANPRADUB — 2023-12-20

The freshwater crocodile or Siamese crocodile (Crocodylus siamensis) is a critically endangered species, with the Kaeng Krachan National Park playing a crucial role in its long-term conservation. This study aimed to investigate the habitat of Siamese crocodiles along the Phetchaburi River using direct observations, camera traps, and unmanned aerial vehicles. Over the course of nine rafting trips conducted between January and December 2022, covering a total distance of 315 km, which resulted in a recorded total of 68 encounters with the Siamese crocodiles or an encounter rate of 0.22 per km. The estimated population of Siamese crocodiles consisted of only four individuals. The study identified several environmental factors that influenced the crocodile distribution, with slope, elevation, forest type, cumulative upstream flow rate, and land use pattern ranked in order of importance. These findings underscore the significance of the Phetchaburi River area for the conservation of freshwater crocodile as indicated by a reliability score of 0.99 (SD=0.02). To ensure the successful conservation of Siamese crocodiles, important recommendations include habitat protection. Additionally, the development of a crocodile threat surveillance system, ongoing population studies, and community involvement are essential for sustainable conservation practices, public awareness campaigns, captive breeding and reintroduction programs, and population restoration efforts. This research provides valuable insights into the habitats and environmental factors impacting the survival of freshwater crocodiles, highlighting the critical role of preserving Kaeng Krachan National Park as a sanctuary for this species.

The Utilization Value of Non–timber Forest Products at the Ban Pang Sawan Community Forest, Khok Khwai Sub–district, Ban Rai District, Uthai Thani Province

Punyawat Meesomkid — 2023-12-20

This study aimed to examine the socio–economic utilization value of non–timber forest products and their processing into commodities for the people living in the Ban Pang Sawan Community, Khok Kwai Sub–district, Ban Rai district, Uthai Thani province. Data was obtained by interviewing 94 household heads or representatives and were evaluated using statistical analysis which included frequency, percentage, minimum, maximum, and mean.

The results indicated that most of the people utilizing the non–timber forest products in Ban Pang Sawan community were male (67.0%), with an average age about 51.7 years, among which 58.5% had elementary school education. The main occupation was agriculture, (51.1%), with an average household income of 139,825.70 Baht/year and an average expenditure of around 103,881.80 Baht/year. The average land holding was 5.7 rai, with 46.8% of the individuals having some debt. In total, 10 types of non–timber forest products used were firewood, bamboo, bamboo shoots, wild fruits, wild vegetables, mushrooms, tuber crops, insects, and insect products, small animals and medicinal plants with an estimated total net value of 632,653.50 Baht/year or 6,730.50 Baht/year/household. Mushroom collection had a net value of 202,547.00 Baht/year or 2,154.80 Baht/year/household. Among the surveyed individuals, 34% faced some issues in gathering non–timber forest products. Within the individuals, 43.6% of them did non–timber forest products processing which included charcoal, pickled bamboo shoots and pickled mushrooms with fish sauce, and were valued at 12,424.80, 86,170.00, and 40,000.00 Baht/year, respectively. These processed goods were used in the household, for sale, and for additional income generation in the household. Therefore, government agency units should promote the processing of non–timber forest products for household utilization as a source of additional household income.

Evaluation of the Damage Caused by the Bamboo Caterpillar (Omphisa fuscidentalis) in Sweet Giant Bamboo (Dendrocalamus latiflorus) at the Royal Agricultural Station Pangda, Chiang Mai Province

Wannapa Keawnin — 2023-12-20

The present study reports on the damage caused by the bamboo caterpillar, Omphisa fuscidentalis to the sweet giant bamboo, Dendrocalamus latiflorus, growing in the Royal Agricultural Station Pangda, Samoeng district, Chiang Mai province. During a period from September 2020 to February 2021, the number of bamboo caterpillars, external effects and internal damage characteristics were determined to be used as basic information while providing guidelines for identifying bamboo species suitable for rearing bamboo caterpillars. The results showed that the average number of bamboo caterpillars were 190 larvae/culm. The average number of damaged internodes was 14 internodes/culm. Although the diameter of internodes was unaffected by the bamboo caterpillar, damaged internodes were located at 9th–13th positions, which experienced high levels of damage, and were shortened by an average of 5 internodes per culm. This reduction in length accounted for approximately 48.8% of the damage to the lower part of the internode. Furthermore, the study revealed that wood penetrated the cracks in the bamboo culm, particularly in the area with short internodes. These highly damaged internodes had the highest percentage of bamboo pulp and wood consumption, approximately 70%, but the upper internodes of damaged internodes continued to develop. Based on the results, it was observed that the sweet giant bamboo exhibited a higher quantity and weight of bamboo caterpillars/culm compared to the usual numbers. The study recorded the highest number of bamboo caterpillars at 484 larvae/culm. These findings suggest that the sweet giant bamboo can serve as a guideline for conducting further studies aimed at increasing the yields of bamboo caterpillars/culm.

Above-ground Carbon Storage Estimation of a Reforestation Site at Mae Moh Mine, Lampang Province, Using Sentinel-2 Satellite Data

Weeraphart Khunrattanasiri — 2023-12-20

This research aimed to determine the relationship between above-ground carbon sequestration and vegetation index derived from Sentinel-2 satellite data to estimate the above-ground carbon sequestration of a reforestation site at Mae Moh mine in the Lampang province. Twenty five permanent plots of size 40 m × 40 m were selected and tree data, including diameter at breast height (DBH) and total height (H), were collected. An allometric equation was developed to determine the relationship between the above-ground carbon sequestration and vegetation index through linear regression. The results showed that the above-ground carbon sequestration estimated through RVI (ratio vegetation index) was sufficiently accurate. The model was of the form y = - 65.57 + 57.57x (R² = 0.75), with an RMSE of 11.14 tons of carbon dioxide equivalent per hectare. The average estimated above-ground carbon sequestration was 41.56 tons of carbon per hectare, while the total above-ground carbon sequestered at the reforestation site was 81,843.28 tons of carbon. The average carbon dioxide adsorption was 152.53 tons of carbon dioxide equivalent per hectare, while the total carbon dioxide adsorbed by the reforestation site being 300,374.28 tons of carbon dioxide equivalent.

Growing Stock and Carbon Storage of Bamboo in Ban Pan Pong Chai Community Forest for Comparing Local Utilization Demand

Kachawoot Sriphaya — 2023-12-20

The purpose of the study was to determine the socio-economic conditions, forest ecological characteristics, growth and yield and carbon stock of bamboo in the Ban Pan Pong Chai Community Forest. Key informants who utilized bamboo were interviewed and a forest survey was conducted based on stratified random sampling method. The crown cover density was classified as high, moderate, and low in a permanent sample plot of size 40x40 square meters in six plots with two plots per stratum which were used to estimate 1.57 % of the sample size.

The results found the mixed deciduous forests as the main forest type in the community forest, with the first five dominant tree species namely Canarium subulatum, Pterocarpus macrocarpus, Xylia xylocarpa var. kerri, Shorea obtusa, and Shorea siamensis, respectively. Additionally, five species of bamboo were identified, namely: Dendrocalamus Strictus, Gigantochloa albociliata, Oxytenanthera albociliata, Cephalostachyum pergracile, and Bambusa natans respectively, with Dendrocalamus Strictus found most frequently. The growing stock of bamboo were estimated at 32.36 clumps/rai (202.25 clumps/ha), and 477.92 stems/rai (4,251.06 stems/ha). The tree biomass and carbon stocks were 8.25 ton/rai (51.56 ton/ha) and 12.87 tCO₂e/rai (80.44 tCO₂e/ha), respectively, while the bamboo biomass and carbon stocks were 24.38 ton/rai (152.38 ton/ha) and 42.01 tCO₂e/rai (262.56 tCO₂e/ha), respectively. The bamboo was mainly used for four purposes namely agriculture material, handy craft, broom, and others of 67,172, 10,758, 9,970 and 5,697 stems/year, respectively. A majority of the key informants had business as their main occupation with an average income of 75,001–150,000 Baht per household per year. Around 50% of these respondents indicated to having a debt from the Bank of Agriculture and Agricultural Cooperative.

Recovery in Post-burned Ground-dwelling Insects at the Srinan National Park, Nan Province

Kanniakar Chuatong — 2023-12-20

A study was conducted at the Srinan National Park in Nan province to investigate the recovery of ground-dwelling insects following a fire event. The study area was divided into three distinct habitats: mixed deciduous forest, dry dipterocarp forest, and agricultural zones. The observation sites were further categorized based on the varying time durations after the fire, spanning 1, 10, 30, and 90 days post-burning, as well as unburned control areas. The method involved collecting ground-dwelling insects using pitfall traps from February to July 2022. The findings of the study indicated a total of 127 insect species belonging to 39 families and 11 orders. Among these, the Hymenoptera order exhibited the highest presence, constituting 39.37% of the insect population and present in 70.35% of all the observed areas. Analyzing the distribution across habitats, the mixed deciduous forest had the highest species diversity, followed by agricultural areas and dry dipterocarp forest, with species counts of 53, 48, and 45, respectively. In terms of the post-fire species diversity, the agriculture area had the highest index, followed by the dry dipterocarp forest and mixed deciduous forest, with scores of 3.13, 3.00, and 2.94, respectively. Comparing the similarity between different areas, the similarity index ranged from 0.45 to 0.70. Through Pearson Correlation analysis, it was determined that the number of insect species, as well as the individual insect count, were correlated with the soil temperature. Notably, only the abundance of ground-dwelling insects was significantly correlated with soil temperature (p<0.01) across all the post-burned durations. These results emphasize the role of soil temperature in influencing the recovery of ground-dwelling insects after a fire event.

The Community Structure of Ground Dwelling Insects at Wang Nam Yen Botanical Garden, Sakaeo Province

Somrudee Janbooppa — 2023-12-20

The community structure of ground dwelling insects was determined at Wang Nam Yen Botanical, Sakaeo Province. The research locations were divided into a natural forest area, Fabaceae planted area and herb garden area. Insects residing on the ground were captured using pitfall-traps and Winkler extractors. The samples were collected every two months between May 2022 and April 2023. The findings revealed that the total number of ground dwelling insects could be classified into 273 species, belonging to 75 families and 12 orders. The highest number of insect species were from the Hymenoptera order (78 species), followed by Coleoptera and Diptera (64 and 34 species, respectively). The highest index of species diversity was found in the natural forest, followed by the Fabaceae planted area and the herb garden (4.49, 4.47, and 4.45, respectively), with the areas having an evenness value between 0.79 and 0.80. The similarity index was moderate, ranging from 0.58 to 0.64. A higher number of ground dwelling insect species was found during the wet season relative to the dry season (234 and 158 species, respectively). Soil moisture and season were significantly associated with the number of ground dwelling insect species in all areas (p<0.05). In summary, we conclude that the seasonal fluctuations and soil moisture had an impact on the community structure of ground dwelling insects.

Species Diversity and Carbon Storage in Biomass of Tree and Sapling in the Ban Nong Kwang Community Forest, Uttaradit Province

Boonsueb Sengbuntan — 2023-12-20

This study aimed to determine the plant community characteristics and biomass carbon storage of trees and saplings in an exploited area of Ban Nong Kwang Community Forest, Uttaradit Province, spread over an area of 804 rai. Ten sample plots of size 40 m x 40 m were randomly established in three zones according to the watershed classification area. All the trees and saplings were identified and measured for their diameter at breast height (DBH) and total height. The importance value index (IVI) was used to identify the dominant species. The biomass of trees and saplings was calculated using allometric equations, and the carbon storage in the biomass was estimated.

There were 75 tree species in 61 genera and 32 families found in the study area. Among these, the Rubiaceae family had the highest number of tree species (9 species), followed by Fabaceae (8 species), Dipterocarpaceae, Anacardiaceae, Malvaceae, and Bignoniaceae (5 species), while the other families had less than 5 species. Based on the IVI, Xylia xylocarpa (Roxb.) W.Theob. var. xylocarpa was the most dominant tree species. The total tree density was between 122.5–177.8 trees/rai (765.63–1,111.25 trees/ha), and the Shannon-Wiener index of species diversity was between 2.54–2.97. The total biomass (aboveground and belowground) was estimated to be between 15.04–16.93 tons/rai (94.00–105.81 tons/ha), with there being no significant differences in biomass among the watershed classes (P>0.05). The carbon storage in biomass was between 7.07–7.96 tons/rai (41.19–49.75 tons/ha). The total carbon stock in the study area was estimated at 6,087.93 tons, accounting for 22,322.41 tonCO₂e. These results can be used as a baseline for developing the Thailand Voluntary Emission Reduction Program (T-VER).

Seedling Communities of Mixed Deciduous and Dry Dipterocarp Forests under the Invasion of Chromolaena odorata in Nam Tok Tat Sai Rung Forest Park, Chiang Rai Province

Saowaros Chompoothep — 2023-12-25

This study aimed to quantitatively characterize the seedling community in two forest types: mixed deciduous forests (MDF) and deciduous dipterocarp forests (DDF), under invasion by Chromolaena odorata. Seedling community characteristics were recorded from 60 temporary sampling plots of size 1 m x 1 m, which were systematically located in Nam Tok Tat Sai Rung Forest Park, Chiang Rai province. The study identified 24 and 17 species seedling tree species in the areas of MDF and DDF invaded by C. odorata, respectively. These species were from 23 genera and 16 families and 16 genera and 13 families of MDF and DDF, respectively. The seedling tree densities were 16,538 and 5,000 stems/ha, respectively. It was also not found that almost all the areas in MDF and DDF were invaded by C. odorata. The identified seedlings were from 17 species, 16 genera, 13 families, and 8 species, 7 genera, and 6 families in the two forest types, respectively, with seedling densities of 12,884 and 10,576 stems/ha, respectively. Comparing the biomass of the invaded areas, it was found that the highest biomass was in the community of C. odorata, followed by the understory vegetation and tree seedlings, respectively. Conversely, in the non-invaded areas of MDF, the seedling tree biomass was higher than in the community of C. Odorata, which was different from that in the DDF. However, the biomass of the understory vegetation in both MDF and DDF was lower than that of the community of C. odorata. The invasion of C. odorata had a significant impact on tree species such as Shorea obtusa, Shorea siamensis, Syzygium oblatum, and Castanopsis acuminatissima. It was found that very few seedlings could establish in the dense growth of C. odorata areas compared to the non-invaded areas. Therefore, sustainable management practices should consider establishing structural tree planting to enhance the chances of successfully establishing native tree species with high importance value index, as well as studying tree species that are resistant to the invasion of such non-native species. These measures will help increase the appropriate quantity of tree seedlings to maintain the ecological system of specific forest communities. Furthermore, raising awareness and disseminating knowledge about the impact of invasive species among the future stakeholders is crucial to ensure a sustainable use of the area.

The Termite (Subterranean Macrotermes carbonarius) attack Rating of Thermally Treated Teak (Tectona grandis L.f.) Plywood

Douangta Bouaphavong — 2023-12-25

Thermal treatment on teak veneer has been recognized as the improved biological property protection method of teak-plywood product from the termite attacking. The objective was investigated how much rating of teak plywood that attacked by termite at the different level of temperature and length of time. The temperatures were at the control, 180, 200, 220, and 240 °C applied at three different lengths of time, i.e., 4, 8, and 12 min on teak veneer sheets. The plywood production was applied two type adhesives with Phenol formaldehyde PF and Urea Formaldehyde UF, both samples was placed in the ground (50 cm deep, 50 cm width and 5 m length with contact with termite home). As the results showed the evidence attacked by termite at different level of temperature at 220 and 240 °C on 4, 8, and 12 min was significant different it is increased as per the temperature in both adhesives. Thermal treatment veneer at 220 and 240 °C can protected termite attacking on teak plywood product as well.

A Clonal Test of Acacia Hybrid at Lad Krating Plantation, Chachoengsao Province

Sopida Yeesoonsee — 2023-12-26

The objectives of this study were to investigate the variation in growth, survival, and phenological characteristics of an Acacia hybrid at Lad Krating plantation, Chachoengsao Province to select clones suitable for the Lad Krating plantation. A total of 37 clones were selected, out of which 27 clones were selected from the clone bank of Lad Krating plantation and 10 clones were obtained from the Royal Forest Department (RFD) through a randomized complete block design (RCBD) with four replicates from the 37 clones. Growth characteristics were measured every six months and phenology characteristics (stem straightness, axis persistence, and branch thickness) were collected for 24 month old trees.

Results of the study indicated that the average diameter at breast height (DBH) at ages 6, 12, 18, and 24 months were 1.40±0.57, 4.19±1.07, 6.23±1.40, and 8.08±1.68 cm, respectively, while the average heights were 2.50±0.45, 4.22±0.76, 6.81±1.24 and 8.96±1.40 m, respectively. The survival rate for trees of age 6, 12, 18, and 24 months-old were 91.34±9.42%, 93.92±6.94%, 88.30±11.33% and 86.97±11.72%, respectively. The measured phenology characteristics for 24 month old trees indicated that the stem straightness (on a scale of 4 points) had an average score of 3.31±0.67, axis persistence (on a scale of 6 points) had an average score of 3.24±1.17, and the branch thickness (on a scale of 4 points) had an average score of 2.07±0.92. Most characteristics of Acacia hybrids from the RFD had a high growth performance and phenology characteristics apart from branch thickness. The clones ranked according to five characteristics DBH, height, survival rate, stem straightness, axis persistence and branch thickness indicated, that clones No. 34, 33, 31, 37 and 35 had the highest perfomance at the Lad Krating plantation.

Forest Structure and Carbon Storage of trees in the Huai Sataeng Watershed Management Unit, Thung Chang District, Nan Province

Kanttanut Kawinpolasa — 2023-12-26

This study aimed to investigate the forest structure and carbon storage of trees in the Huai Sataeng Watershed Management Unit, Thung Chang district, Nan province. The forest area in the unit is located at elevation ranging from 500 - 900 m above sea level. Sample plots of size 40 m x 40 m were placed according to the specific height above the mean sea levels of 500, 600, 700, 800 and 900 m, respectively. In each plot, trees, saplings and seedling data were collected to assess the relative density, relative frequency, relative dominance, and importance value index (IVI). The biomass also was calculated using allometric equations and the carbon stocks were estimated. The unit had a total of 89 species in 69 genera and 42 families of plants. The density of tree, saplings, and seedlings were 803, 40,500 and 764,000 (tree/ha), respectively. The top five indicator tree species in the Huai Sataeng Watershed Management Unit were Lithocarpus fenestratus, Aporosa villosa, Croton persimilis, Pterocarpus macrocarpus, and Schima wallichii. The total aboveground biomass of all species was 423.49 t/ha, with the tree, saplings, and bamboo biomass contributing 367.74, 1.83 and 53.92 t/ha, respectively. Additionally, the total carbon stock was estimated at 199.04 t/ha.