The Effects of Adding Heartwood Extractives from Acacia confusa on the Lightfastness Improvement of Refined Oriental Lacquer

In this study, a renewable polymeric material, refined oriental lacquer (ROL), used as a wood protective coating, and the Acacia confusa Merr. heartwood extractive, which was added as a natural photostabilizer for improving the lightfastness of ROL, were investigated. The best extract conditions for preparing heartwood extractives and the most suitable amount of addition (0, 1, 3, 5, and 10 phr) were investigated. The lightfastness index including brightness difference (ΔL *), yellowness difference (ΔYI), and color difference (ΔE *), and their applied properties of coating and film were measured. In the manufacture of heartwood extractives, the yield of extractives with acetone solvent was 9.2%, which was higher than that from toluene/ethanol solvent of 2.6%, and also had the most abundant total phenolic contents (535.2 mgGAE/g) and total flavonoid contents (252.3 μgRE/g). According to the SEM inspection and FTIR analysis, the plant gums migration to the surface of films and cracks occurred after UV exposure. The phenomena for photodegradation of ROL films were reduced after the addition of heartwood extractives. Among the different amounts of the heartwood extractives, the 10 phr addition was the best choice; however, the 1 phr heartwood extractive addition already showed noticeable lightfastness improvement. The drying times of ROL were extended and film performances worse with higher additions of heartwood extractives. Among the ROL films with different heartwood extractive additions, the ROL film with 1 phr addition had superior films properties, regarding adhesion and thermal stability, compared with the films of raw oriental lacquer.

Host Plants of the Immature Stages of the Invasive Longan Lanternfly, Pyrops candelaria (L.) (Hemiptera, Fulgoridae) in Taiwan

The longan lanternfly, Pyrops candelaria (L.), has been invading mainland Taiwan since 2018, but the distribution of the species has been confined to northern Taiwan until now. The manual removal of the adult insects from the longan is still the main control strategy because of the uncertainty around other key host plants, especially for eggs and nymphs. In this study, large numbers of eggs and nymphs were found on Triadica sebifera (L.) Small and Acacia confusa Merr. The occurrence of immature individuals on Triadica sebifera increased with developmental stage from eggs to the last instar from May to July 2021. On April 30, the first egg mass was recorded. More egg masses were recorded in May, and some could be found in July. In May, only two younger instars were detected. Third and fourth instars began to appear from June, while the fifth instar was mainly recorded from July onwards. The results of this study provide great strategic value for decision-makers to allow for effective control of the target tree species. For now, we proved that longan and pomelo trees, preferred by adults, are not the key hosts for the immature stages of this insect, because few immature individuals were found on them. Therefore, we suggest that the existence of Triadica sebifera should be considered when analyzing possible spreading areas of this invasive lanternfly in Taiwan.

Reforestation of Degraded Landscapes in Micronesia

Wildfires on degraded grasslands cause extensive soil erosion and cause environmental and economic damage worldwide. We conducted fertilizer, lime, and mulch trials to improve growth of trees planted in acid soils in degraded grasslands on the Micronesian islands of Guam, Rota, and Yap. Fertilizer application had no effect on height growth of Acacia auriculiformis seedlings on a Mollisol on Guam while lime application had a small but significant positive effect on height growth. Fertilizer application had a significant positive effect on height growth of Acacia confusa seedlings planted on an Oxisol on Rota but lime had no effect. Mulch application increased height growth of Swietenia macrophylla seedlings planted on an Oxisol on Yap but lime application had no effect. Collaboration between university researchers and local forestry agencies can improve reforestation success, but researchers need to consider local capabilities and local knowledge.

Properties of a formaldehyde-free tannin adhesive and mechanical strength of oriented bamboo scrimber board bonded with it

In this study, oriented bamboo scrimber board (OBSB) was manufactured with a synthesized formaldehyde-free tannin adhesive. The chemical properties of the tannin adhesive were analyzed with 13C nuclear magnetic resonance spectroscopy (13C-NMR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). Results revealed that 70% aqueous acetone extractives of Acacia confusa bark (AcBAE) contained abundant phenolic compounds and condensed tannins comprising mainly B-type flavonoid bonds. Moreover, cross polarization magic angle spinning (CP/MAS) 13C-NMR mapping of cured Acacia confusa bark tannin glue (AcBTanGlu) revealed that condensed tannin reacted with hexamethylenetetramine to form a polymer with a cross-link structure through a polymerization mechanism. According to the results obtained from gas chromatography-flame ionization detector (GC-FID) analysis, no formaldehyde was emitted from AcBTanGlu-glued OBSB. Thermogravimetric analysis indicated that AcBTanGlu significantly improved the thermal stability of AcBAE after the curing reaction. Comparison of the DRIFT spectra of bamboos before and after AcBTanGlu-glued treatment indicated AcBTanGlu did not impact the chemical functional properties of the bamboo. Compared to phenol formaldehyde (PF) and urea formaldehyde (UF)-glued OBSBs, AcBTanGlu-glued OBSBs statistically had lower modulus of elasticity (MOE) and modulus of rupture (MOR). As for the nail withdraw resistance, AcBTanGlu-glued OBSBs are statistically comparable to PF-glued OBSBs and higher than UF-glued OBSBs.

Screening of broad-leaved tree species to restore Eucalyptus urophylla Blake forest on Sanjiao Island, China

This study aimed to test the allelopathic effects of Eucalytus urophylla Blake. forest soil on 5-native broad-leaved tree species (Bauhinia purpurea L., Acacia confusa Merr., Acacia podalyriifolia A. Cunn. ex G. Don., Celtis sinensis Pers. Liquidambar formosana Hance) to select suitable species for restoration of E. urophylla forest. Three types of soils [E. urophylla soil, other plants soil and bare soil] were used to determine their allelopathic potential. The total phenols concentrations in soil were measured, and the correlations between total phenols and plant growth indices were analyzed. E. urophylla soil significantly inhibited the basal diameters of Bauhinia purpurea L. and Acacia confusa Merr. and biomass of Acacia podalyriifolia A. Cunn. ex G. Don. but significantly improved the biomass of Celtis sinensis Pers. and diameter of Liquidambar formosana Hance. The total phenols in soil accounted for these results, except for A. podalyriifolia. Thus, L. formosana, C. sinensis and A. confusa can be suggested as suitable tree spp to establish mixed stands with E. urophylla. Besides, B. purpurea, A. podalyriifolia, A. confusa and L. formosana can be used for restoration in bare soil, while B. purpurea, A. confusa and L. formosana are suitable species to restore vegetation in other plants soil. Keywords: Acacia confuse, Acacia podalyriifolia, Allelopathy, bare soils, Bauhinia purpurea, broad-leaved trees, Celtis sinensis, Eucalytus urophylla, E. urophylla soil, forest restoration, island, other plants soil, rhizosphere soil, total phenols