In this study, we surveyed plant species composition at sites with varying light conditions and ground water levels (GWLs) in Nyukasa Marsh, Nagano Prefecture, Japan. The 66 study sites were classified into six community types (A-F) based on cluster analysis. Plotting study sites using non-metric multidimensional scaling revealed that light conditions and GWLs affected species composition. Sites with both high GWLs and light levels were characterized by wetland species such as Carex thunbergii var. thunbergii. Conversely, sites with high GWLs but low light levels were distinguished by other wetland species such as Impatiens noli-tangere. Sites with low GWLs and high light levels supported flowering plants such as Convallaria majalis var. manshurica and Iris ensata, which are eye-catching and potentially attractive for tourists. Wet sites with moderate light levels were classified into two community types, each with unique indicator species. Sites with both low GWLs and light levels mostly comprised forest-floor and pasture species, indicating vegetational succession caused by the drying out of wetland.

Plant communities on rocky coasts are established in response to the shoreline-to-inland transitional environmental gradient as well as to various environmental conditions on rocky shores.　In addition, rocky coast is an essential habitat for threatened and endemic plants.　Our research aimed to study plant communities comprising sea cliff herbaceous vegetation and their environmental conditions, and to clarify the relationships between communities and important conservational plant species on the Miura Peninsula, Kanagawa Prefecture, eastern Japan.　Using modified TWISNAPN, vegetation data of 123 stands were divided into 11 communities.　Almost all communities were equivalent or similar to the associations already known around the study area （e.g., Fimbristylidetum ferrugineae Ohba 1970 and Chrysanthemo-Miscanthetum condensati Ohba 1971）.　On the other hand, some communities differed from the known associations in the Kanto region.　Five communities were established on wet elevated abrasion platforms or wave cut benches, and the environmental conditions of these communities show unique hydrological conditions and water quality.　The other six communities were established on sea cliffs, and the environmental conditions of these communities showed unique soil characteristics and intensities of location stability caused by slope gradient and elevation differences.　In 7 of the 11 communities, there were 13 national or prefectural endangered species and 8 endemic species, and almost all of these were combined within specific communities.　The locations of these communities were gently sloping and likely to be sensitive to human activity.　To conserve herbaceous communities and the diversity of plant species on rocky coasts, it is important to focus on differences in site fragility across communities.

Clove oil extracted from the leaves of clove trees (Syzygium aromaticum) is an important cash crop in East Java, Indonesia. The standard monoculture that has been recently adopted for clove oil production can reduce biodiversity. We investigated the plant species occurrence in a typical mixed-culture (MIX) stand growing clove trees and other crops, and compared it with that in a clove monoculture (MON) stand in East Java, Indonesia, in order to examine the advantage of MIX in conserving plant species diversity. We recorded the occurrence of vascular plants in the understory at 20 quadrats (1 m × 1 m) each systematically placed in a 20 m × 100 m plots established for both MIX and MON. Altogether, 46 plant species were found in the two plots. MIX and MON included 40 and 17 species, respectively, indicating far greater species richness in MIX with a diverse life form composition and large numbers of woodland and/or native species. The α- and the β-diversities were higher in MIX than MON, which is associated with a high dissimilarity of plant occurrence among the quadrats within the plot. These results suggest the superiority of MIX for conserving plant species diversity compared to MON. Among the microsite conditions examined, no significant differences between MIX and MON were observed for soil water content (SWC) and sky factor (SF). The species number per quadrat was positively correlated with SF in both MIX and MON, but the correlation was weaker in MON than in MIX. The understory vegetation cover (UVC) and the litter cover (LC) showed wider ranges in MIX compared to those in MON. UVC was correlated positively with the species number in both stands. LC showed negative and positive correlations to species number in MIX and MON, respectively. From these results, we concluded that in MON, the human disturbances to the soil surface associated with frequent clove litter collection from the whole stand reduced the plant species richness by inhibiting plant establishment and cancelling the positive effects of the variability in physical environment, and that the higher species richness of MIX was due to alleviating the effects of litter-collection disturbances, which facilitated the effects of the heterogeneous physical environment within the stand.

Betula costata Trautv. (Betulaceae) is a canopy tree species found in mixed broadleaved-coniferous forests and is widely and continuously distributed in continental Northeast Asia. This species is also found in the mountains in the central of Honshu in the Japanese archipelago, meaning that it has a disjunct geographical distribution. However, there have been few studies on the types of forest vegetation in which this species appears in Japan. Here we surveyed the habitat and species composition of forest vegetation in which B. costata appears in central Honshu, Japan using a phytosociological approach for the first time. A total of 19 relevés of the B. costata forests of Japan were collected and classified into four community types belonging to the class Fagetea crenatae:Alnus firma-Betula costata community, Abies homolepis-Betula costata community, Aesculus turbinata-Betula costata community, and Pterocarya rhoifolia-Betula costata community. The occurrence of B. costata in these communities indicates that this species grows in secondary and disturbed forests in soil with high water retention capacity. Furthermore, we compared the species composition of the B. costata forests of Japan with that of the B. costata forests of continental Northeast Asia and found considerable differences between the two regions. These differences would indicate the outcome of historical climatic and vegetation changes in Japan and continental Northeast Asia.

Large-scale phytosociological survey data are gathered globally and used for environmental conservation. The Japanese government collects vegetation data accompanied by national vegetation mapping and publishes it in a database. However, classifying large-scale databases using traditional phytosociological table manipulation is time- and labor-intensive. Although the automated approach is expected to classify large-scale vegetation data rapidly, it is necessary to verify its consistency with the established classification system for practical use. Thus, I compared traditional classification and ISOPAM, a recently developed automated approach, for classifying Japanese coastal beach and dune vegetation for which community classification has already been established. The traditional table manipulation classified 42 herbaceous and 11 shrub communities, most of which corresponded to previously reported phytosociological vegetation units. ISOPAM automatically classified the same dataset into 16 vegetation units using the default settings. These vegetation units corresponded well to major communities with many data obtained through traditional tabular comparison. Plant communities with few data did not correspond to the ISOPAM classification, as they were integrated into major vegetation units. ISOPAM was therefore considered a suitable method for automatically extracting large-scale vegetation patterns using a large dataset. However, rare communities and outliers with few data might be difficult to detect with an unsupervised classification such as ISOPAM. Therefore, a high-quality labeled database needs to be developed as training data based on past phytosociological findings to classify large-scale data efficiently.

Historically, the vegetation of Otome Highland, Yamanashi Prefecture, central Japan, was maintained by mowing and dominated by tall forbs.　However, forbs have been replaced by Miscanthus sinensis, a tall grass, since around 2005, coinciding with an increase in the sika deer population （Cervus nippon）.　Eleven representative plant species were cut 10 cm above the ground.　Among nine forb species, six species died after cutting, and the surviving three species regrew to a shorter height than that of the control plants.　Conversely, M. sinensis and Lespedeza bicolor, a shrub, not only survived but showed no decrease in height over the long term by cutting.　M. sinensis was cut in June, September or November, and both June and September.　These treatments were continued for 5 years.　November cutting did not affect grass height.　June cutting reduced grass height, but this height was maintained over 5 years.　September cutting and June/September cutting steadily reduced the height over 5 years.　Grazing by deer affected the survival and height of forbs, but M. sinensis was slightly or not affected, which explained the replacement of forbs by M. sinensis in Otome Highland.　A deer proof fence of 15 ×15 m was set in the M. sinensis community.　After 4 years, M. sinensis was reduced, and tall forbs had greatly increased or recovered inside the fence.　This resulted in an increase in diversity among the plant community inside the fence （H′ = 2.64）, which was three times greater than that outside （H’ = 0.85）.　Changes in dominant plants in the upper layer of the plant community from tall forbs to M. sinensis affected low-growing ground plants.　Thelypteris palustris, a short fern, was increased among clumps of M. sinensis.　Potentilla freyniana, a prostrate forb, also increased with M. sinensis outside the fence but was decreased with an elongated petiole height inside the fence.　This study demonstrated that deer grazing affects plant communities by three different mechanisms:1） deer preference （unpalatable plants are untouched）, 2） plant response （e.g., ability of plants to recover after defoliation or physical removal of plant parts）, and 3） indirect effects of canopy-forming plants on ground plants.　From these results, we concluded that the replacement of tall forbs by the M. sinensis plant community since 2005 was a result of sika deer grazing.

The Ozegahara moor, located in central Honshu of Japan, has a natural and typical wetland ecosystem, and the area has been preserved as a national park and natural monument.　However, the impacts of sika deer on the wetland vegetation has been conspicuous since the 1990s with the increase in its population.　Although the most noticeable impact of the deer is the disturbance resulting from the digging of Menyanthes trifoliate rhizomes, an influence on the species compositions of other plant communities is also expected due to accumulated grazing and trampling.　Screening the vulnerable plant communities and preferentially protecting them is important to develop a plan for their effective conservation measures.　This study aimed to investigate the changes in species composition of ten representative wetland plant communities of the Ozegahara moor over 50 years, by comparing the vegetation data from the 2010s and the previous data from the 1960s.　The differences in species composition were greater in the low-moor communities, and shrub/forest communities than in the mid-moor and high-moor communities, suggesting that these communities have been affected severely by deer.　The constancy of 24 species decreased significantly from the 1960s in one or more communities.　Changes in the life-form composition were also detected in association with the change in species composition.　Specifically, tall erect herbs were decreased in many communities, whereas tussock graminoids and short non-tussock graminoids increased.　In addition, similarity among different communities was greater in the data from the 2010s than those from the 1960s, indicating a reduction in beta diversity across the wetland vegetation.　Based on these results, we concluded that the species composition of the wetland communities in the Ozegahara moor was affected by sika deer, and low-moor communities and shrub/forest communities around the moor have higher conservation priority.

We investigated climate factors affecting the tree-ring width and seed production of Abies mariesii in a snowy subalpine coniferous stand in a 1-ha permanent plot for the Monitoring Sites 1000 Project in Otanomosu-daira in the Shiga Highland Biosphere Reserve, central Japan.　Wood cores （5 mm diameter） were taken at a trunk height of 50 cm from 40 individuals with various diameters ［mean diameter at breast height, 25.2 cm （range, 9.4-49.4 cm）］ using an increment borer.　Crossdating, standardization, and autoregressive modeling were performed on a tree-ring time series to develop a residual chronology representative of the habitat.　Relationships between the chronology and climate factors during the period 1937-2018 were assessed with Pearsonʼs correlation analysis.　The tree-ring width was positively correlated with the temperatures in November of the previous year and April of the current year; it was negatively correlated with the minimum temperature in July of the previous year.　It also had significant positive and negative correlations with the precipitation in May and July of the previous year, respectively.　A generalized linear model （GLM） was used to analyze the relationship between tree-ring width and seed production, and the effects of climate on seed production during the period 2006-2018.　The GLM showed that there is a trade-off between tree-ring width and seed production in a given year.　However, there was no correlation between seed production in a given year and tree ring width in the following year.　Spring and autumn temperatures （April, May, October, and November） had a negative effect on seed production in the following year, and the mean daily minimum temperature in August had a negative effect on seed production in the current year.　The summer temperature （July and August） positively affected seed production in the following year.　June and August precipitation had a negative impact on seed production in the current year.　The insolation duration in May had a negative effect on seed production in the current and following years, while that in April and June had a positive effect on seed production in the current year, and that in July had a positive effect on seed production in the following year.　These results suggest that increases in temperature in the spring and autumn due to global warming will encourage tree-ring growth and reduce seed production of A. mariesii in the stand.　They also suggest that increases in summer temperature and insolation duration would promote reproduction;however, seed production may be suppressed by reduced spring insolation duration and increased summer temperature and rainfall.　The relationship between tree-ring width and seed production, and the effects of climate factors thereon in the A. mariesii population, are likely to change further with future climate change.　Continued monitoring is needed for the early detection of such influences.