Invasive plants can release allelopathic compounds that inhibit or enhance the growth of other plants and microorganisms in the surrounding environment. In this study, we performed the next-generation sequencing (NGS) analyses to compare the genes of the soil microbial communities in a natural forest and an open place where Triadica sebifera (L.) Small, a typical invasive plant, grows in Miyajima Island, Hiroshima Prefecture, Japan. We collected soil samples in May 2022, the litter layer of Chinese tallow completely decomposed. Our data suggested that the invaded site of T. sebifera have different genetic composition of soil bacterial and fungal species, and in bacterial metabolic pathways. The result also seemed indicate that T. sebifera recruited several microbes including plant growth-promoting rhizobacteria (PGPRs), such as Sphingomonas, which may be involved two potential degradations of allelopathic compounds in the rhizosphere soil of Chinese tallow tree. A more detailed chemical analysis will also be needed to distinguish whether the allelopathic substances recruiting microorganisms come from the fallen leaves or from the exudation of roots. This study provided a new insight into the invasion and establishment of invasive plants with the possibility of bacteria involved allelopathy process in the soil. We also found that using different kits for extracting DNA and PCR could affect the NGS results.

View full abstract

Livelihood diversification is a coping strategy for destressing or increasing the income of rural households, while promoting sustainable land management. This study was conducted in enclave settlements inside state-owned forests where land encroachment is prohibited. The primary objective was to examine whether livelihood diversification can help control the forest encroachment problem. A household questionnaire survey was conducted in four villages with different level of accessibility. The agricultural land area was calculated for three periods: 2002, 2002–2013, and 2013–2021. The rates of changes were compared these periods. The results demonstrated that encroachment continues, regardless of the policy intervention for livelihood development. We observed four patterns of livelihood diversification and encroachment: 1) highest diversity with a low-income level and an increased rate of encroachment, 2) high diversity with a high-income level and increased rate of encroachment, 3) low diversity with a high-income level and decreased rate of encroachment, and 4) low diversity with a low-income level and decreased rate of encroachment. From this study, it can be concluded that livelihood diversity cannot halt land encroachment. Intensification of non-farm activities and socio-economic factors must be considered in the management of forest encroachment.

View full abstract

Myxomycetes mostly inhabit detritus environments of forests in terrestrial ecosystem. However, differences in myxomycete communities among various vegetation types of local forests have been little known. We examined the myxomycete communities on litter twigs in six types of forests (three types of natural and three types of countryside forests) due to clarify characteristics of the myxomycete diversity in western Japan. Fallen twigs were collected from the forest floor under trees dominating the canopy in all six forests, and moist chamber cultures were established in 640 Petri dishes. In total, 42 taxa belonging to 19 genera were recorded, of which only four species were common to all six forests. The natural broad-leaved evergreen forest (21 taxa) and the country-side pine forest (7 taxa), respectively, showed the highest and lowest α-diversities for myxomycete communities. The species diversity in countryside forests was lower than that in natural forests. Non-metric multidimensional scaling revealed that the myxomycete communities in natural forests distinctively had characteristic community structures and those in country-side forests resembled those in the adjacent natural forests, except in the country-side pine forest. To our knowledge, this is the first comprehensive study on the relationships between forest types and myxomycete communities living on litter twigs in Japan; these findings indicate the potential effects of geographical location and forest types, including biodiversity decreasing influenced by anthropogenic activity.

View full abstract

The isotype of Megaceros aenigmaticus R.M.Schust. was newly found from the Herbarium of the Hattori Botanical Laboratory (nich). Overall, the morphology of the specimen is consistent with the original description for the plants of type locality except for the presence of Nostoc colonies. Given the incongruence of the notations of scientific name between the original publication of Nothoceros aenigmaticus (≡Megaceros aenigmaticus) and the latest world checklist of liverworts and hornworts, the nomenclatural issue of this species was discussed.

View full abstract

Rishiri Island is located near the northernmost coast of Japan, and is of great botanical interest due to the presence of a high-altitude stratovolcano. Through our recent expeditions to this island, we provided notes on some noteworthy Marchantiales taxa. We speculated that human activities and climate changes may cause the decline or disappearance of the populations of the alpine species, such as Peltolepis quadrata, Mannia gracilis and Sauteria alpina, and allow the introduction of some species that prefer low-lying and/or man-made habitats. Since there are few reports on Japanese materials, we gave a detailed illustration of Peltolepis quadrata on its important distinguishing characters. Marchantia polymorpha L. subsp. polymorpha is reported as new to Hokkaido. The distribution and taxonomic status of Cleveaceae taxa in Japan requires further reevaluation.

View full abstract

A crustose lichen Graphis cleistoblephara Nyl. (Ascomycota, Graphidaceae) was found in Miyajima (Itsukushima) Island, Hiroshima Prefecture, SW Japan; the first record of G. cleistoblephara for the Chugoku Region, SW Japan. Morphological and chemical notes on this species based on the specimens from Miyajima Isl., are provided and its biogeographical relationships. Its phylogenetic position is inferred based on mt SSU rDNA sequences in the genus Graphis, detecting intraspecific variation in sequence.

View full abstract

Lysimachia sikokiana Miq. (Primulaceae) is a rare plant species distributed in the Seto Inland Sea area, SW Japan, and has been listed as an RDB species of Hiroshima Prefecture. Located in the south of Hiroshima Pref., Miyajima Island is an important geographic location because it is near the northern limit of L. sikokiana. Here we report the current growing condition of this species on Miyajima Island and provide the basic information for its conservation. The height of L. sikokiana was smaller than plants growing in other places. The reasons for this might include environmental change in addition to the Wright effect and the distribution being close to its northern limit. Furthermore, the local population is disappearing, and the existing population showed a decrease in both population size and plant growth. The results suggested that closure of the forest canopy gaps has been associated with a decrease in light intensity and water content on forest floor, altering the favorable environment of L. sikokiana. Natural disturbances, such as tree fall caused by typhoons that create canopy gaps, have not occurred in recent years, and no canopy gaps have been made in places where L. sikokiana is present. This study sheds light on the status of the local population of L. sikokiana on Miyajima Island and demonstrates the need for ex-situ conservation.

View full abstract