Hrvatski Sumarski Institut (Croatian Forest Research)Acta Medica Okayama1849-08911712026Understory Vegetation Structure in Remnant Natural Forests and Acacia Plantations on Coastal Sand Dunes in North Central Vietnam26007ENTuan QuocDoanOkayama University, Graduate School of Environmental, Life, Natural Science and TechnologyTetsuya K.MatsumotoIbaraki University, Graduate School of Science and EngineeringTai TienDinhHue Union of Science and Technology Associations (HUSTA)Hung ThaiLeHue University, University of Agriculture and ForestryTuan Ngoc AnhHoHue Union of Science and Technology Associations (HUSTA)Naoko H.MikiOkayama University, Graduate School of Environmental, Life, Natural Science and TechnologyHoang Thai DacHoHue Union of Science and Technology Associations (HUSTA)MunetoHirobeOkayama University, Graduate School of Environmental, Life, Natural Science and TechnologyIn the coastal sand dune forests of North Central Vietnam, vegetation has been seriously damaged by war and overexploitation. To recover ecosystem functions, including sand stabilisation under harsh environments, exotic species like Acacia spp. have been planted as a monoculture. However, the long-term sustainability of this practice remains unclear. To assess the long-term effectiveness of revegetation with Acacia spp., this study aims to understand the differences and similarities in ecological characteristics of remnant natural forests and Acacia plantations on the coastal sand dune of North Central Vietnam by comparing understory vegetation structure and environmental conditions. We investigated the understory vegetation (height < 130 cm) in a total of 54 quadrants (1 m ~ 1 m), including nine natural forests and nine Acacia plantations. We compared diversity indices by mixed ANOVA and examined the differences in the understory vegetation structure between the two forest types through PERMANOVA. We also determined some abiotic environmental factors (e.g. light and soil water availability, and soil pH). We identified 951 individuals, with 792 found in natural forests and 159 in plantations. The species found in natural forests were well-distributed among Liana phanerophytes (Lp), Microphanerophytes (Mi), Mega-Mesophanerophytes (MM), and Cryptophytes (Cr). In contrast, species found in plantations were predominantly Cr, Hemicryptophytes (Hm), and MM. All diversity indices were significantly higher in natural forests (P < 0.05), and the NMDS analysis confirmed significant differences in the understory vegetation structure between natural forests and plantations. Only soil pH was significantly lower in natural forests (P < 0.05), while none of the environmental factors had a statistically significant impact on the variations in understory vegetation structure. Our results indicate that succession by native tree species does not seem to occur naturally in Acacia plantations. Hence, to restore and sustainably develop coastal sand dune forests in North Central Vietnam, it is essential to establish a scientifically based strategy for managing and protecting the remaining natural remnant forest areas.No potential conflict of interest relevant to this article was reported.Springer Science and Business Media LLCActa Medica Okayama1860-18712026Effects of Juniperus sabina coverage on plant community structure in semiarid areas of ChinaENLongQinGraduate School of Environmental and Life Science, Okayama UniversityAyakaYamabayashiGraduate School of Environmental and Life Science, Okayama UniversityTetsuya K.MatsumotoFaculty of Environmental and Life Science, Okayama UniversityGuoshengZhangCollege of Ecology and Environment, Inner Mongolia Agricultural UniversityNorikazuYamanakaArid Land Research Center, Tottori UniversityMunetoHirobeFaculty of Environmental and Life Science, Okayama UniversityNaoko H.MikiFaculty of Environmental and Life Science, Okayama UniversityPlant interactions are one of the fundamental processes shaping the structure and function of plant communities and help create species diversity. Species diversity affects the current functioning of ecosystems and their resistance and resilience to future climate change. In harsh environments such as drylands, positive plant–plant interactions are important in promoting species diversity. Juniperus sabina is an evergreen shrub that is native to the semiarid areas of northern China. Because J. sabina can modify some harsh environmental conditions in its role as a nurse plant, it is expected to facilitate species diversity, although it may exhibit allelopathic inhibition. Previous research has only examined effects of J. sabina coverage onฟ-diversity in a single-year, and its effects on the ภ-diversity of the plant community structure in the local ecosystem are still unclear. We compared environmental conditions and plant species composition inside and outside of 11 J. sabina patches to evaluate the effects of its coverage on the species diversity of the understory community structure through modifying microhabitat conditions. Water and nutrient conditions were higher inside the patches, whereas light conditions were higher outside. More perennial herbs and C3 plants were found inside and more annual herbs and C4 plants were found outside. There were different trends in ฟ-diversity each year, while ภ-diversity was consistently greater inside the patches. This research suggests that the coverage of J. sabina can drive different community structures by providing heterogeneous environmental conditions, and would increase plant species diversity in the local ecosystem.No potential conflict of interest relevant to this article was reported.African Journals Online (AJOL)Acta Medica Okayama1726-801X3982025Chemical composition of essential oil of Acacia crassicarpa Benth. (Fabaceae) from Vietnam16531660ENTuanQuoc DoanGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityTaiTien DinhHue Union of Science and Technology Associations (HUSTA)TetsuyaK. MatsumotoGraduate School of Science and Engineering, Ibaraki UniversityDienDinhPhong Dien Nature Reserve, Phong Dien district, Thua Thien Hue provinceNaokoMikiGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityMunetoHirobeGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityHoaiThi NguyenFaculty of Pharmacy, Hue University of Medicine and Pharmacy, Hue UniversityThis research aimed to identify the volatile compounds found in the fresh leaves of Acacia crassicarpa Benth. This is the first phytochemical investigation of this species. Essential oils from the leaves of A. crassicarpa were obtained by hydro-distillation and analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Sixty-one compounds accounting for 95.8% of the leaf oil were identified. The classes of compounds identified in the oil sample were aldehydes (30.7%), sesquiterpene hydrocarbons (25.2%), alkanes (19.1%), oxygenated monoterpenes (3.6%) oxygenated sesquiterpenes (2.3%), monoterpene hydrocarbons (0.8%) and others (14.2%). The major constituents in the leaf oil were tridecanal (24.5%), (E)-caryophyllene (11.7%), n-heneicosane (7.2%), squalene (6.5%), and 7-tetradecenal (5.9%).No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama2223-77471352024The Impact of Phenological Gaps on Leaf Characteristics and Foliage Dynamics of an Understory Dwarf Bamboo, Sasa kurilensis719ENChongyangWuBeijing for Bamboo & Rattan Science and Technology/International Centre for Bamboo and Rattan, Key Laboratory of National Forestry and Grassland AdministrationRyotaTanakaFaculty of Agriculture, Okayama UniversityKyoheiFujiyoshiFaculty of Agriculture, Okayama UniversityYasuakiAkajiBiodiversity Division, National Institute for Environmental StudiesMunetoHirobeDepartment of Environmental Ecology, Graduate School of Environmental and Life Science, Okayama UniversityNaokoMikiDepartment of Environmental Ecology, Graduate School of Environmental and Life Science, Okayama UniversityJuanLiBeijing for Bamboo & Rattan Science and Technology/International Centre for Bamboo and Rattan, Key Laboratory of National Forestry and Grassland AdministrationKeijiSakamotoDepartment of Environmental Ecology, Graduate School of Environmental and Life Science, Okayama UniversityJianGaoBeijing for Bamboo & Rattan Science and Technology/International Centre for Bamboo and Rattan, Key Laboratory of National Forestry and Grassland AdministrationPhenological gaps exert a significant influence on the growth of dwarf bamboos. However, how dwarf bamboos respond to and exploit these phenological gaps remain enigmatic. The light environment, soil nutrients, leaf morphology, maximum photosynthetic rate, foliage dynamics, and branching characteristics of Sasa kurilensis were examined under the canopies of Fagus crenata and Magnolia obovata. The goal was to elucidate the adaptive responses of S. kurilensis to phenological gaps in the forest understory. The findings suggest that phenological gaps under an M. obovata canopy augment the available biomass of S. kurilensis, enhancing leaf area, leaf thickness, and carbon content per unit area. However, these gaps do not appreciably influence the maximum photosynthetic rate, total leaf number, leaf lifespan, branch number, and average branch length. These findings underscore the significant impact of annually recurring phenological gaps on various aspects of S. kurilensis growth, such as its aboveground biomass, leaf morphology, and leaf biochemical characteristics. It appears that leaf morphology is a pivotal trait in the response of S. kurilensis to phenological gaps. Given the potential ubiquity of the influence of phenological gaps on dwarf bamboos across most deciduous broadleaf forests, this canopy phenomenon should not be overlooked.No potential conflict of interest relevant to this article was reported.Springer Science and Business Media LLCActa Medica Okayama1860-1871172021Effects of large-scale forest fire followed by illegal logging on the regeneration of boreal forests in Mongolia267279ENKeijiSakamotoGraduate School of Environmental and Life Science, Okayama UniversityMisakiTomonariGraduate School of Environmental and Life Science, Okayama UniversityUyangaAriyaGraduate School of Environmental and Life Science, Okayama UniversityErikaNakagiriGraduate School of Environmental and Life Science, Okayama UniversityTetsuyaMatsumotoGraduate School of Environmental and Life Science, Okayama UniversityYasuakiAkajiCenter for Environmental Biology and Ecosystem Studies, National Institute for Environmental StudiesTakashiOtodaGraduate School of Environmental and Life Science, Okayama UniversityMunetoHirobeGraduate School of Environmental and Life Science, Okayama UniversityBaatarbilegNachinSchool of Engineering and Applied Sciences, National University of MongoliaWe aimed to test the hypothesis that large-scale forest fire followed by illegal logging inhibits the regeneration of boreal forests in Mongolia. For this purpose, we compared regeneration of the forest between five stands in a large-scale post-fire site, i.e., (1) undisturbed stand in the unburnt and remaining forest, (2) stand disturbed by illegal logging in the unburnt and remaining forest, (3) stand disturbed by forest fire, (4) stand disturbed by forest fire followed by illegal logging and located in proximity to the remaining forest, which acts as a seed source, and (5) stand disturbed by forest fire followed by illegal logging and located far from the remaining forest, which acts as a seed source. The stand disturbed by logging showed similar species composition of regenerated individuals as the undisturbed stand. In the stand disturbed by logging, Picea obovata and Pinus sibirica were abundant because of advance regeneration on the intact forest floor. In the stand disturbed by forest fire and that disturbed by forest fire followed by illegal logging, Larix sibirica and Betula platyphylla were abundant, and the regenerated individuals of these two species were new individuals after the disturbances. L. sibirica was abundant in the stand disturbed by forest fire because the mother trees survived the forest fire because of their thick bark. B. platyphylla was abundant in the stand disturbed by forest fire followed by illegal logging because the mother trees of L. sibirica were logged and the seeds of B. platyphylla are able to disperse further than that of L. sibirica. However, in the stand disturbed by forest fire followed by illegal logging that was located far from the remaining forest, the regeneration was much reduced because only few seeds, including that of B. platyphylla, were dispersed into this stand and sprouts of B. platyphylla were damaged by the logging operation. In addition, the regeneration of L. sibirica and B. platyphylla was likely to have been reduced for several years after the forest fire because of the loss of safe sites for their invasion by the changes of the forest floor conditions. Therefore, it is likely that large-scale forest fires that are followed by illegal logging inhibit the regeneration in many parts of the post-fire site and those parts will change into open forests of B. platyphylla or grassland.No potential conflict of interest relevant to this article was reported.ชRๅw_wActa Medica Okayama0474-0254@9512006XMlHัฬฮสษมฝy๋fฎิฬ๓ิIฯฎ9395ENMunetoHirobeSpatial variabillity of soil nitrogen(N) dynamics was examined along a slope in a 45-year-old Cryptomeria japonica D.Don plantation in the southeastern paet of Shiga Prefecture. Net N mineralization showed no clear gradient along the slope, while net nitrification and percent nitrification were high at lower positions,and very low at upper positions of the slope. Principal component(PC) analysis showed soil properties were divided into three groups which were PC1(water content and pH), and PC3(total C and N). Regressions of net soil N transformations against PCs scores suggested net N mincralization was mainly regulated by PC3, while net nitrification and percent nitrification were mainly regulated by PC1 and PC2. The difference in the main form of inorganic N was expected to affect soil N availability for plants through the difference in the mobility in negatively changed forest soil. We evaluated the soil N availability that reflebted the ion mobility factors by ion exchange resins and found that greater mobility of nitrate lead to greater soil N availability at lower positions of the slope. In addition, gross N transformations were directly measured using <sup>15</sup>N isotope dilution, and the influence of microbial caebon (C) availability on the internal soil N cycles were examined by long-term laboratory incubation. Gross nitrifivation was detected in both soils taken at upper and lower positions on the slope, suggesting that nitrification was also an important process at upper positions where almost no net nitrification was detected. Changes in net and gross N transformations, the organic C and N pools, and microbial respiration suggested that start of rapid net nitrifibation might be affected not only by the availability of C for microbial biomass, but also by the relative availability of C and N.No potential conflict of interest relevant to this article was reported.