Termites are the most destructive pests and their attacks significantly impact the quality of wooden buildings. Due to their cryptic behavior, it is rarely apparent from visual observation that a termite infestation is active and that wood damage is occurring. Based on the phenomenon of acoustic signals generated by termites when attacking wood, we proposed a practical framework to detect termites nondestructively, i.e., by using the acoustic signals extraction. This method has the pros to maintain the quality of wood products and prevent higher termite attacks. In this work, we inserted 220 subterranean termites into a pine wood for feeding activity and monitored its acoustic signal. The two acoustic features (i.e., energy and entropy) derived from the time domain were used for this study’s analysis. Furthermore, the support vector machine (SVM) algorithm with different kernel functions (i.e., linear, radial basis function, sigmoid and polynomial) were employed to recognize the termites’ acoustic signal. In addition, the area under a receiver operating characteristic curve (AUC) was also adopted to analyze and improve the performance results. Based on the numerical analysis, the SVM with polynomial kernel function achieves the best classification accuracy of 0.9188.

Gambir is one of the most economically important natural products of Indonesia. Indonesia accounts for 80% of the global exports of this product. The product contains catechin, a phenolic compound of the flavonoid group, which has demonstrated bioactivity against horticulture-destroying fungi. However, its bioactivity in controlling wood-decaying fungi has not yet been reported. A laboratory study was conducted to examine the characteristics of the catechin of gambir and its bioactivity against the wood-decaying fungi Schizophylum commune Fr. Extraction of catechin from gambir was conducted via a gradual maceration process using hot water (70 °C, 3 h) followed by ethyl acetate (1:10 w/v, 4 h). The chemical components of catechin were analyzed by gas chromatography mass spectrometry (GCMS), while its bioactivity against S. commune was examined according to EN 113 (1986). The results showed that there were five chemical components in catechins, i.e., 1,2-benzenediol, catechol, 1,3,5-benzenetriol, dimethyl terephphtalate, and terephthalic acid. These compounds demonstrated the ability to remarkably inhibit the growth of S. commune.

The population of South Jakarta, a city within the Province of Jakarta Capital Region, is increasing annually, and the development of land into building causes termite diversity loss. The aim of this research was to determine the diversity of subterranean termite species and their distribution in South Jakarta and to evaluate the soil profile termite habitat. This study was conducted in South Jakarta and was carried out at four residential areas representing four randomly selected sub-districts. Specimens were collected with a baiting system. At each residence, as many as 25–30 stakes of pine wood (Pinus merkusii) sized 2 cm × 2 cm × 46 cm were placed for termite sampling. Soil samples were also collected from each residence for testing of their texture, pH, soil water content, and C-organic. Three species of subterranean termites were identified, including Coptotermes curvignathus, Microtermes insperatus, and Macrotermes gilvus, with area-specific variations in occurrence. The soil and weather conditions in the studied areas provided suitable habitat for termites, and M. insperatus was the most commonly found species.

Rain tree (Samanea saman) is a dominant species commonly planted as a shade tree in urban landscapes in the tropics, including in Indonesia. This species is also targeted for routine inspection and monitoring within tree management systems. Management should particularly focus on tree health through assessment of tree growth conditions as well as tree stability. However, baseline information on the relationships of many key characteristics for the rain tree (e.g., growth, morphometrics, and biomechanics) is lacking. Therefore, an investigation was carried out to determine the relationship of morphometric parameters to tree growth, which included use of an acoustic tool to assess the elasticity of the tree stem. Fifty rain trees were selected for data collection and evaluated using stress wave velocity tools and visual morphometrics assessment. The results demonstrated that, in general, the trees had good vigor and stability. Statistical analysis showed a strong relationship between tree growth parameters and selected morphometric characteristics. The use of a nondestructive acoustic-based instrument enabled determining the modulus of elasticity, which provided equivalent results with the elasticity value obtained through a common method for determining tree stability. Only live crown ratio and tree slenderness parameters had a relationship with the dynamic modulus of elasticity. These results offer a means of measurement that is simpler, less expensive, and faster than current methods, although further testing is needed for different tree species and growth sites.

Sengon (Falcataria moluccana Miq.) is one of the fastest growing wood that is broadly planted in Indonesia. Sengon wood has inferior wood properties, such as a low density and dimensional stability. Therefore, sengon wood requires a method to improve its wood quality through wood modification. One type of wood modification is wood impregnation. On the other hand, Betung Bamboo leaves are considered as waste. Betung Bamboo leaves contain silica. Based on several researches, nano-SiO₂ could improve fast-growing wood qualities. According to its perfect solubility in water, monoethylene glycol (MEG) is used in the study. The objectives are to evaluate the impregnation treatment (MEG and nano-silica originated from betung bamboo leaves) in regard to the dimensional stability and density of 5-year-old sengon wood and to characterize the treated sengon wood. MEG, MNano-Silica 0.5%, MNano-Silica 0.75%, and MNano-Silica 1% were used as impregnation solutions. The impregnation method was started with 0.5 bar of vacuum for 60 min, followed by 2.5 bar of pressure for 120 min. The dimensional stability, density, and characterization of the samples were studied through the use of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the treatment had a significant effect on the dimensional stability and density of sengon wood. Alterations in the morphology of treated sengon wood were observed through the full coverage of the pits on the vessel walls (SEM analysis results) and the detection of ethylene (FTIR analysis results) and silica (XRD and FTIR analysis results). Overall, the 0.75% MNano-Silica treatment was the most optimal treatment for increasing the dimensional stability and density of 5-year-old sengon wood.

The root system is important for supporting tree growth and stability. In this study, we analyzed the relationship between the main lateral root distribution pattern and vertical tree growth direction based on root detection and analysis of tree morphometry. Tree growth represented by morphometric data were measured directly, and the root distribution was identified using a sonic Root Detector. Sixteen targeted trees (eight Samanea saman and eight Delonix regia trees) in an urban area landscape were selected in this study. The Root Detector revealed that the average sonic velocity of lateral roots was 676.88 m∙s⁻¹ for S. saman and 865.32 m∙s⁻¹ for D. regia. For root distribution, Root Detector determined the average numbers of main lateral roots for S. saman and D. regia, which were 6 and 10, respectively. Based on correlation analysis, significant relationships were found between tree root sonic velocity and the degree of lean, height, and diameter of the tree; meanwhile the relationship between crown diameter and slenderness were not significant. Findings confirmed that, in relation to the root distribution and the growth direction of the trunk and crown, the lateral root is mainly distributed in the opposite direction of the tree lean rather than crown growth direction.