In 2020, within the Dongbaekdongsan area in Jeju Island, a Septobasidium sp. associated with a felt disease in Castanopsis sieboldii (Makino) Hatus. ex T. Yamaz. & Mashiba was identified. The symptom included the presence of brown, thin, and silk-like mycelial mats attached to the tree's bark, displaying variations in size from large to small. To induce hyphal growth, the samples collected were incubated in a moist chamber, and the newly formed hyphae were subjected to genomic DNA extractions. The nucleotide sequences of the internal transcribed spacer and small subunit rDNA genes were determined, and molecular characteristics among the isolates were investigated through polymerase chain reaction-based restriction fragment length polymorphism analysis. This Septobasidium sp. exhibited distinct morphological and phylogenetic features compared to those that were previously reported in South Korea. Consequently, this strain is taxonomically classified as a provisionally novel species of Septobasidium. Furthermore, the observed felt disease exhibited a high degree of host specificity, as it was exclusively identified in C. sieboldii without occurrence in other tree species at the time of observation.

Wind barriers play a vital role in protecting saplings until maturity when planted as vegetative windbreak forests. Most previous studies have focused on the porosity of wind barriers, but no studies have simultaneously examined the effects of the porosity and inclination, despite the potential of the inclination to decrease wind speed. We tested three wind barrier cases in wind tunnel experiments: (1) Case A (porosity of 0% with inclinations (90°, 80°, and 70°)), (2) Case B (porosity of 25% with inclinations (90°, 80°, and 70°)), and (3) Case C (porosity of 50% with inclinations (90°, 80°, and 70°)). The vertical and horizontal wind velocities were measured at three vertical and seven horizontal points behind the barriers. The results demonstrated a statistically significant decrease in the correlation between the distance and mean wind velocity for all cases, with up to a six-fold wind protection effect. The wind barrier with 0% porosity and a 90° inclination provided the highest degree of wind protection. However, the wind protection range was limited downwind, and recirculation of wind flow could occur in the leeward direction, potentially damaging saplings. A wind barrier with 50% porosity and 70° inclination sufficiently decreased the wind velocity and prevented recirculation of wind flow, demonstrating that both porosity and inclination considerably impacted the wind protection effect by reducing wind velocity. Our findings offer novel insights into the influence of wind barriers with varying porosities and inclinations and can provide valuable guidance for constructing efficient windbreak forests.

Phytoplasmas were discovered in diseased Elaeocarpus sylvestris trees growing on Jeju Island that showed symptoms of yellowing and darkening in the leaves. Leaf samples from 14 symptomatic plants in Jeju-si and Seogwipo-si were collected and phytoplasma 16S rRNA was successfully amplified by nested polymerase chain reaction using universal primers. The sequence analysis detected two phytoplasmas, which showed 99.5% identity to ‘Candidatus Phytoplasma asteris’ and ‘Ca. P. malaysianum’ affiliated to 16SrI and 16SrXXXII groups, respectively. Through polymerase chain reaction-restriction fragment length polymorphism (RFLP) analyses using the AfaI (RsaI) restriction enzyme, the presence of two phytoplasmas strains as well as cases of mixed infection of these strains was detected. In a virtual RFLP analysis with 17 restriction enzymes, the 16S rRNA sequence of the ‘Ca. P. asteris’ strain was found to match the pattern of the 16SrI-B subgroup. In addition, the phytoplasmas in the mixed-infection cases could be distinguished using specific primer sets. In conclusion, this study confirmed mixed infection of two phytoplasmas in one E. sylvestris plant, and also the presence of two phytoplasmas (of the 16SrⅠ and 16SrXXXⅡ groups) in Jeju Island (Republic of Korea).

Phytoplasma has been newly detected in Elaeocarpus sylvestris, a tree species that grows on the island of Jeju, South Korea. Various symptoms of infection of E. sylvestris have appeared since 2013, including loss of leaf coloration, such as yellowing, darkening and branch dieback. We analyzed leaves and seeds of E. sylvestris sequences infected by phytoplasma, and found partial 16S rRNA sequences to be 99.5%, and secA genes 98.2% correlated with Malaysian periwinkle virescence group strain ELY-BN1, MaPV, MOP, MYD, and TtWB. Analyzing these sequences and through the virtual restriction fragment length polymorphism (virtual-RFLP), we report here the first occurrence of Elaeocarpus decline associated with a phytoplasma strain belonging to 16SXXXII groups, as well as the first detection of phytoplasma in the seeds of E. sylvestris in South Korea.

Wildfires impact forest ecosystems, affecting tree survival and physiological responses. This study explored the effects of surface fires on Pinus densiflora and Quercus variabilis, assessing mortality, internal injuries, and canopy health. By 2024, P. densiflora had an 18.0% mortality rate, whereas Q. variabilis exhibited no crown dieback. Morphological traits, including tree height, the bark scorch index (BSI), and bark thickness, influenced fire resistance. Despite superior stand characteristics, P. densiflora showed higher mortality due to thin bark, whereas Q. variabilis maintained xylem integrity. While sonic tomography (SoT) showed no significant differences, electrical resistance tomography (ERT) detected physiological stress, with higher ERT_R and ERT_Y area ratios correlating with mortality risk. Notably, F-W-W classified trees showed elevated resistance a year before mortality, suggesting ERT as a predictive tool. ERT_R values exceeding 15.0% were associated with a 37.5% mortality rate, whereas ERT_B values below 55.0% corresponded to 42.9% mortality. Despite fire exposure, canopy responses, including chlorophyll fluorescence and photosynthetic efficiency, remained stable, indicating that the surviving trees maintained functional integrity. This study underscores ERT’s efficacy in diagnosing fire-induced stress and predicting mortality risk. The findings highlight species-specific diagnostic criteria and inform post-fire management, supporting forest resilience through the early detection of high-risk trees and improved restoration strategies.

We report a previously unrecorded woody species, Stachyurus praecox Siebold & Zucc. (Stachyuraceae), in Korea. This species is considered to be endemic to Japan. Stachyurus praecox was collected for the first time in an evergreen forest on an uninhabited island of Bongsun-ri, Saengil-myeon, Wando-gun, Jeollanam-do in Korea. The inflorescence of the species was racemose and pendulous on the axils of the previous year’s branches. Flowers bloomed from March to April. They were functionally dioecy but morphologically hermaphrodite. This woody species was named ‘Wan-do-sul-kkot-na-mu’ in Korean based on the shape of its inflorescence. Morphological characteristics and illustrations of this woody species have been provided with a distribution map and photographs of the natural habitat.