Tateyama Caldera Sabo Museum

A lack of information persists on external seed dispersal interactions, despite the rich diversity of potential dispersers. Roadkills offer a unique opportunity to obtain ecological data directly from carcasses. For 18 years, we collected road‐killed mammals in Toyama (Japan) and screened them for seed attachment. We then illustrated species interactions, quantified the number of plant species and seeds individual roadkill carried, and evaluated seasonal variations in the probability of seed attachment. We identified nine mammal species dispersing seeds from 16 distinct plant taxa. Most importantly, medium‐sized mammals (1.5–10.0 kg) accounted for approximately 88% of roadkill carrying seeds, with raccoon dogs Nyctereutes procyonoides dispersing the most seeds. Likely due to seed‐set phenology, we showed a significant increase in seed prevalence for roadkills occurring in autumn. We advocate for future studies in epizoochory to focus on potential animal dispersers community wide.

The retrieval of continuous ice core records of more than 1 Myr is an important challenge in palaeo-climatology. For identifying suitable sites for drilling such ice, the knowledge of the subglacial topography and englacial layering is crucial. For this purpose, extensive ground-based ice radar surveys were done over Dome Fuji in the East Antarctic plateau during the 2017–2018 and 2018–2019 austral summers by the Japanese Antarctic Research Expedition, on the basis of ground-based radar surveys conducted over the previous ~ 30 years. High-gain Yagi antennae were used to improve the antenna beam directivity and thus attain a significant decrease in hyperbolic features in the echoes from mountainous ice-bedrock interfaces. We combined the new ice thickness data with the previous ground-based data, recorded since the 1980s, to generate an accurate high-spatial-resolution (up to 0.5 km between survey lines) ice thickness map. This map revealed a complex landscape composed of networks of subglacial valleys and highlands, which sets substantial constraints for identifying possible locations for new drilling. In addition, our map was compared with a few bed maps compiled by earlier independent efforts based on airborne radar data to examine the difference in features between sets of the data.

Tsuji, Yamato, Toshiaki Shiraishi, Kenta Sawada, Matsubara, Miki, Kosugi, Jun (2021): Differential Attraction of Large and Small Tunneling Dung Beetles (Coleoptera: Geotrupidae and Scarabaeidae) to Native Mammal Dung in a Satoyama Forest in Central Japan. The Coleopterists Bulletin 75 (2): 376-381, DOI: 10.1649/0010-065X-75.2.376, URL: http://dx.doi.org/10.1649/0010-065x-75.2.376

<strong class="journal-contentHeaderColor">Abstract.</strong> Since 2012, seven perennial snow patches in the northern Japanese Alps have been determined to be very small glaciers (VSGs: <span class="inline-formula"><i>&lt;</i>0.5</span> km<span class="inline-formula">²</span>). However, it had not been determined how such glaciers could be maintained in such a warm climate. In this study, we calculate the annual mass balance, accumulation depth, and ablation depth of five of these VSGs, covering 2015–2019 for four of them (2017–2019 for the fifth) using multi-period digital surface models (DSMs) based on structure-from-motion–multi-view-stereo (SfM–MVS) technology and images taken from a small airplane. The results indicate that, due to snow acquired from avalanches and snowdrifts, these VSGs are maintained by an accumulation in winter that is more than double that from the snowfall, thereby exceeding the ablation in summer. Therefore, we classify them as topographically controlled VSGs. We find very small yearly fluctuations in their ablation depth; however, their annual mass balance and accumulation depth have large yearly fluctuations. The annual mass balance, which mainly depends on the accumulation depth, showed accumulation throughout each glacier during heavy snow years and ablation throughout each glacier during light snow years. This characteristic differs from the upper accumulation area and lower ablation area that exists on most glaciers. These VSGs lack a positive annual mass balance gradient, which suggests that they are not divided by a distinct glacier equilibrium line altitude (ELA) into an upstream accumulation area and a downstream ablation area. Moreover, compared to other glaciers worldwide, we find the mass balance amplitude of VSGs in the northern Japanese Alps to be the highest measured to date.

The Japanese Northern Alps, facing the Sea of Japan and composed of several high mountains with peaks over 3,000 m above sea level, are known to form one of the heaviest snowfall areas in the world. However, the horizontal distribution of snow cover and inter-annual and seasonal variations of snow cover have not been understood completely because of a lack of observations. Therefore, numerical simulations are conducted using the Nonhydrostatic Regional Climate Model (NHRCM) with 2-km and 5-km grid spacings (hereafter, NHRCM02 and NHRCM05, respectively), and the simulations are compared to snow cover observations at Murododaira and along the Tateyama-Kurobe Alpine Route. Both NHRCM02 and NHRCM05 simulate interannual variations of snow depth observed at Murododaira in mid-March and late April well, although the snow depth is slightly overestimated. Compared to snow cover observations in the winter of 2014/15, NHRCM05 has remarkably large biases of snow depth at Midagahara and Daikandai. The overestimations of snow depth are improved by NHRCM02 at these stations. The 17-year-mean maximum snow depth shows that NHRCM05 calculates a greater snow depth at the windward side of the Japanese Northern Alps than does NHRCM02, which also influences the altitudinal dependence of snow depth. The horizontal resolution of NHRCM05 is not high enough to resolve convective precipitation over the Sea of Japan in winter. Therefore, NHRCM05 simulates less precipitation over the Sea of Japan and more over mountainous areas than NHRCM02, which results in large snow cover biases at the windward side of the Japanese Northern Alps.

山崎断層帯南東部に属する琵琶甲断層の西側セグメントを横切る測線に沿ってaudio-frequency Magnetotelluric法探査を行い,深さ1.5kmまでの2次元比抵抗構造モデルを得た.このモデルは表層付近の低比抵抗層,深さ350~約500mに側方に連続する低抵抗領域,および深さ900~約1400mの2つの低比抵抗領域で特徴付けられる.琵琶甲断層西側セグメントの地下の浅部および深部には断層活動に関係する低比抵抗領域があり,これらは琵琶甲断層の地下形状を示すと考えられ,また,琵琶甲断層東側セグメントが西側セグメントの北東側に延伸し並行して存在することが示唆された.山崎断層帯北西部に属する土万断層の2次元比抵抗構造モデルと比較すると,断層直下の低比抵抗領域および深部の低比抵抗領域の端が断層地表トレースと一致することは共通するが,後者の断層に対する相対位置が異なる様子が見いだされた.

Abstract AimCryoconite, a microbe‐mineral aggregate found on glaciers worldwide, is formed by microbial phototrophs, principally cyanobacteria. Despite their ecological importance in supraglacial environments, the phylogeographical distributions of supraglacial cyanobacteria are poorly understood. Here, we investigate the biogeographical distribution of cyanobacteria on glaciers in the Antarctic, Arctic and Asia.LocationGlaciers in the Antarctic, Arctic and Asia.MethodsWe analysed contiguous sequences of 16S rRNA genes and 16S–23S internal transcribed spacer (ITS) regions, determined by a long read strategy and single‐filament PCR analysis in 38 glacial samples. We analysed cyanobacterial distribution patterns and genetic differentiation.ResultsThe cyanobacterial 16S rRNA gene sequences were grouped into 20 operational taxonomic units (OTUs), and the six major OTUs that accounted for 88% of sequences were distributed broadly from polar to Asian glaciers, suggesting that they are cosmopolitan at the species level. However, analysis of the more variable ITS region revealed geographical differentiation at the strain level. Nineteen OTUs, including the six major OTUs, showed considerable genetic differentiation among geographical regions; at the population level, they are, thus, geographically restricted. Only one of the phylotype exhibits a population structure which does not show a relationship with geographical distribution, suggesting that is cosmopolitan, even at the strain level.Main conclusionsOur 16S rRNA gene analyses suggest a global distribution of species of cyanobacteria colonizing glacier surfaces; however, the 16S–23S ITS regions revealed that most of the phylotypes are fundamentally endemic to particular areas at the population level and indicate limited migration among regions. Our result suggests that selection pressures among geographical regions are strong driving forces shaping genetic structure in cyanobacteria.

We performed airborne synthetic aperture radar (SAR) observations at two glaciers (San’nomado and Komado glaciers) on the eastern slope of Mt. Tsurugi, Japan, in August and October 2013, and August 2014. The Pi-SAR2 system used in this study consists of two X-band SAR antennas. Taking advantage of single-pass interferometry, we have generated digital elevation models (DEM) at each epoch. Differencing the DEMs at August and October 2013, the elevations at the glaciers were reduced by ~20m or more with errors on the order of ~20m or more. As we could visually identify the reduction in the snow-covered areas in the SAR images of August and October 2013, those changes are attributable to seasonal melting of the snow but are apparently overestimated. Full polarimetric observations were also performed, indicating significant changes over the glaciers from August to October that were largely due to the reduction in snow cover. We could further identify localized spots that indicated strong intensity in the cross-polarized HV channel (transmission of vertically polarized wave and reception in horizontally polarized channel) over the glaciers. Bright HV signals are unexpected, because HV signals are often interpreted as volume scattering and appear to originate from the inside of the glaciers that are unlikely in the X-band SAR system; no penetration deeper than 1m is expected in the X-band over the snow/ice areas. We interpret the apparent HV signals as due to double bouncing from both sides of the valley, which were apparently imaged over the glaciers.

This study focuses on the results of an audio-frequency magnetotelluric (AMT) survey across the Jigokudani valley, Tateyama volcano, Japan, to investigate the spatial relationship between the distribution of electrical resistivity and geothermal activity and to elucidate the geologic controls on both its phreatic eruption history and recent increase in phreatic activity. The AMT data were collected at eight locations across the Jigokudani valley in September 2013, with high quality data obtained from most sites, enabling the identification of an underground 2D resistivity structure from the transverse magnetic (TM) mode data. The data obtained during this study provided evidence of a large conductive region beneath the surface of the Jigokudani valley that is underlain by a resistive layer at depths below 500 m. The resistive layer is cut by a relatively conductive region that extends subvertically toward the shallow conductor. The shallow conductive region is divided into an uppermost slightly conductive section that is thought to be a lacustrine sediment layer of an extinct crater lake containing hydrothermal fluids and a lower section containing a mix of volcanic gases and hydrothermal fluids. The low permeability of the clay zone means that the uppermost clayey sediments allow the accumulation of gases in the lower section of the conductive region, suggesting the existence of a cap structure. The deep resistive layer likely consists of units similar to the granitic rocks that are widely exposed throughout the Jigokudani valley. We suggest that the relatively conductive zone that separates these granitic rocks represents a high-temperature volcanic gas conduit, given that the most active fumarole in the Jigokudani valley lies directly along the trajectory of this path.