Hokkaido Region Research Articles

Quantifying the shear behavior of fine-grained soil with herbaceous plant roots under freeze-thaw conditions using X-ray CT scan

This study investigates the reinforcement effect of Kentucky bluegrass roots on slope soil under freeze-thaw conditions, with a focus on the Hokkaido region of Japan. Using direct shear tests combined with X-ray CT scanning, we analyzed the impact of root parameters (such as root mass and volume) on the shear strength of root-soil composites. The results revealed that freeze-thaw cycle did not cause significant root breakage or diminish the root system's ability to stabilize the soil compared to non-freeze-thaw conditions. Root-soil samples demonstrated notable ductility during shear deformation, with shear stress continuing to increase after reaching peak values. In contrast, soil samples stabilized after reaching peak shear stress without further increase. Although no significant differences in shear behavior were observed between root-soil and soil samples in the initial shearing stage, the freeze-thaw cycle led to some consolidation in root-soil samples, reducing their resistance to elastic deformation. Moreover, longer root growth periods resulted in a more pronounced increase in shear stress. CT scan image reconstruction allowed us to quantify root system parameters, such as root volume and distribution near the shear plane, which showed a strong correlation with maximum shear stress. Our findings demonstrate the effectiveness of herbaceous plant roots, particularly Kentucky bluegrass, in maintaining soil stability under freeze-thaw conditions.

The Influence of Planting Density on the Flowering Pattern and Seed Yield in Peanut (Arachis hypogea L.) Grown in the Northern Region of Japan

In peanut cultivation in the Tokachi region of Hokkaido, Japan, it is essential to complete the harvest by early October to prevent frost damage. Therefore, cultivation methods that can accelerate the flowering period are necessary. It is understood that planting density can influence the timing of flowering, with crops often flowering earlier at higher densities. This study aimed to investigate whether growing peanuts at higher densities could advance the flowering period and, consequently, enhance yield. The Japanese peanut variety, Tachimasari, was cultivated in 2022 and 2023 at a conventional planting density of 5.8 plant m−2 (D5.8) and at density conditions of 8.7 plant m−2 (D8.7) and 11.6 plant m−2 (D11.6). The D8.7 and D11.6 plants reached the peak of flowering 2.8 and 5.1 days earlier, respectively, and the end of flowering 3.7 and 8.0 days earlier than the D5.8 plants. Although the total number of flowers was higher in D5.8, pod fertility was greater in D8.7 and D11.6, where plants were able to reduce the occurrence of ineffective flowers and immature pods. Consequently, higher seed yields were observed in D8.7 (2709 kg ha−1) and D11.6 (2754 kg ha−1), where lower individual productivity was offset by higher planting densities, compared to the conventional density condition of D5.8 (2169 kg ha−1).

Future Change in the Contribution of Riming and Depositional Growth to the Surface Solid Precipitation in Hokkaido, Japan

Abstract This study examined future changes in the microphysical properties of surface solid precipitation over Hokkaido, Japan. A process-tracking model that predicts the mass of the hydrometeors generated by each cloud microphysical process was implemented in a meteorological model. This implementation aimed to analyze the mass fraction of hydrometeors resulting from depositional growth and the riming process to the total mass of surface solid precipitation. Results from pseudo–global warming experiments suggest two potential future changes in the characteristics of surface solid precipitation over Hokkaido. First, the rimed particles are expected to increase and be dominant over the west and northwest coast of Hokkaido, where heavy snowfall occurs primarily due to the lake effect. Second, the mass fraction from depositional growth under relatively higher temperatures is expected to increase. This increase is anticipated to be dominant over the eastern part and mountainous area of Hokkaido. Additionally, the fraction of liquid precipitation to total precipitation is expected to increase in the future. These results suggest that the microphysical properties of solid precipitation in Hokkaido are expected to be similar to those observed in the current climate over Hokuriku, the central part of Japan even in warmer climate conditions. Significance Statement This study examines potential future changes in the growth processes contributing to surface precipitation particles in Hokkaido, Japan. The surface solid precipitation particles in the western and eastern regions of Hokkaido are mainly generated through depositional growth that occurs within the temperature ranges −36° to −20°C and −20° to −10°C, respectively. A future shift is anticipated, with riming becoming the primary process. This shift suggests that snowfall particles will be heavier than those in the current climate, which would increase the snow-removal workload. The change in precipitation characteristics could influence adaptation and mitigation strategies for climate change in cold regions.

Assessment of soybean productivity and its changing factors in Japan based on the production cost statistics

Soybean (Glycine max [L.] Merr.) yields have remained below 2.0 t ha−1 for over 30 years in Asian countries, indicating long-term stagnation in productivity and production technology. This study aimed to measure the total factor productivity (TFP) of soybean production in Japan and to assess the factors affecting TFP and yield. The Färe–Primont index of TFP was measured for two agroclimatic regions using soybean production cost statistics from 1987 to 2015 to analyze the regression of TFP and yield with per-farm land size, time trends, and production-related input variables. The TFP increased by 1.5–2.4 % annually in the two regions, despite an annual decrease of 0.7 % in country's average yield. The TFP in the subarctic Hokkaido region improved by 9–15 % due to the land-size increase and progress of time, i.e., technological progress, during the period. While in the temperate main-island region, a 14 % TFP increase induced by increased land size was largely offset by the time–progress effect (−11 %), i.e., technological retrogression. Similar time–progress effects observed on yield indicated that technological changes occurred, with respect to cultivation methods. The TFP–improving land-size increase adversely resulted in a 9 % yield decrease in the main-island region accounting for 85 % of soybean cultivation area in Japan. The results further showed that TFP improved by saving production inputs, such as fertilizer, per unit area in both regions, and the yield rose with increased inputs in seed, agrochemicals, and rental services, depending on the region. This study revealed continual soybean TFP improvements across Japan due to land-size increases and input saving in addition to the regionally biased progress in cultivation technologies. The implications of the results are discussed from the perspective of improving TFP and yield while increasing the per-farm land size.

Activity Report of the Hokkaido Regional Chapter

Activity Report of the Hokkaido Regional Chapter

Taxonomic re-evaluation of the subspecies of Hebius vibakari (Boie, 1826) (Reptilia: Serpentes: Natricidae), with new evidence from central and northern China.

Hebius vibakari (Boie, 1826), the type species of the genus Hebius, currently includes three subspecies: Hebius vibakari vibakari, endemic to Japan except for the Hokkaido region; Hebius vibakari ruthveni (Van Denburgh, 1923), found in the Korean Peninsula, northeastern China, and eastern Russia; and Hebius vibakari danjoensis (Toriba, 1986), native to the Oshima Island, Danjo Islands, Japan. However, the taxonomic status of three subspecies has not been evaluated for many years. Integrating data from previous studies and new records from central and northern China, we evaluated the systematic positions of H. v. vibakari and H. v. ruthveni based on comparative morphology and molecular phylogenetics. Analysis recovered H. vibakari as a monophyletic group, composed of three major clades that could not correspond to the nominative subspecies. As molecular and morphological evidence could not distinguish H. v. ruthveni from H. v. vibakari, we synonymized the junior nomen H. v. ruthveni with H. v. vibakari. A detailed description of Hebius vibakari is provided, including hemipenial morphology, and the taxonomic status of the subspecies H. v. danjoensis is discussed.

A PrOsPective Cohort Study on Interstitial Lung Disease-Associated Pulmonary Hypertension with a ParticulaR Focus on the Subset with Pulmonary Arterial Hypertension Features (POPLAR Study).

The pathogenesis and clinical profiles of patients with pulmonary hypertension (PH) associated with interstitial lung disease (ILD-PH) are poorly understood. Whether and to what extent pulmonary arterial hypertension (PAH)-specific therapy improves hemodynamic and outcome in ILD-PH are also unknown. This study aims to clarify the characteristics, clinical course and response to PAH-specific therapy of ILD and/or PH by enrolling three unique subsets: PAH, ILD-PH, and ILD. The proposed study is a retrospective and prospective, multi-centre, observational cohort study of patients treated at any of three university hospitals in the Hokkaido region of Japan who have any one of the following: PAH; ILD-PH with or without PAH features; or ILD without PH. We aim to enrol 250 patients in total. For the retrospective observation period, data obtained after 1 January 2010, will be analysed, and the prospective observation period will be 1year. We will compare the clinical data of patients with ILD-PH with those of patients with PAH and those of patients with ILD without PH in the real-world clinical setting. In addition, within the cohort of patients with ILD-PH, we will explore the subset with "ILD-PH with PAH features" and compare the response to PAH-specific therapy with that of PAH. The primary outcome will be the change in pulmonary vascular resistance from first treatment to follow-up in patients with PAH and ILD-PH with PAH features (excluding ILD-PH without PAH feature and ILD-no-PH for the primary outcome). The exploratory outcomes will include analyses of PH-associated biomarkers, right ventricular function and patient-reported outcomes. This is a protocol article and the results will be presented after data collection is completed. The POPLAR study will provide data that help better understand the pathophysiology of ILD-PH and improve the quality of life and outcome of patients with PH and/or ILD. Japan Registry of Clinical Trials: jRCT1010230018.

Possible Shifts in the Genetic Diversity of Red-crowned Cranes (Grus japonensis) in Hokkaido, Japan: Indications of Continental Gene Flow.

Red-crowned cranes (Grus japonensis) consist of two distinct groups: the continental population and the island population. The island population, localized in Hokkaido, Japan, exhibits very low genetic diversity due to its rapid recovery from the brink of extinction. Our previous research in 2018 highlighted a possible mating between a male from the continental population, with the Gj5 haplotype, and a female from the island population, with the Gj2 haplotype, at Hitominuma Sawmp shore in northern Hokkaido. The present study attempted to unravel the distribution of their offspring by examining the major histocompatibility complex (MHC) of this mixed breeding pair compared with samples collected from cranes in northern and southeastern Hokkaido between 2008 and 2022. The analysis identified 55 MHC types, including 10 known types in a dataset of 89 crane samples, based on amino acid sequences. A total of 58 MHC types were recognized, based on nucleotide sequences, as there were many cases in which the same amino acid sequence had different nucleotide sequences. The five DNA types of MHC in the Hitominuma Swamp male were predominantly identified in eight cranes from northern Hokkaido and one chick from southeastern Hokkaido. In addition, population genetic analysis, based on insertion/deletion (InDel) polymorphisms, indicates distinct population differentiation between the northern and southeastern regions of Hokkaido. These results suggest that genetic contributions from the continental red-crowned crane population have already been integrated into the Hokkaido populations, with a more pronounced influence in northern Hokkaido.

Climate impacts on high-intensity sapling mortality: Comparative study and future warnings for Larix kaempferi, Abies sachalinensis, and Picea glehnii

Climate change profoundly affects plant viability and forest dynamics, creating uncertainty in future forest management. Post-planting, high-intensity sapling mortality may require costly replanting, disrupting plans, and risking forest management goals. Therefore, this study focused on high-intensity sapling mortality (mortality rates exceeding 30 %) in Larix kaempferi, Abies sachalinensis, and Picea glehnii planted in northern Japan attributed to summer drought. Utilizing a dataset spanning approximately three decades, the correlation between high-intensity mortality occurrence and climatic stress was explored employing a Bayesian approach. Additionally, the probability of high-intensity mortality occurrence by the end of this century was predicted based on two representative climate scenarios (RCP2.6 and RCP8.5). The predictive accuracy of high-intensity mortality occurrence probabilities exceeded 70 % after comprehensive consideration of climatic stress factors, thereby accentuating the robustness of the proposed model. These encompass the antecedent precipitation index (API), which serves as a soil drought indicator; 30-day mean daily maximum temperature (MaxTMP̅); 30-day mean daily total solar radiation (TSR̅); and day of year (DOY). All sapling species manifested a pronounced negative correlation between API and the probability of high-intensity mortality occurrence, whereas TSR̅ exhibited a positive impact on this probability. Additionally, MaxTMP̅ positively influenced this probability for L. kaempferi and A. sachalinensis. Delving into interspecific differentials, API exhibited the most pronounced impact on P. glehnii in comparison to the other two tree species, whereas TSR̅ exerted a substantial influence on A. sachalinensis and P. glehnii. The susceptibility to MaxTMP̅ was hierarchically ordered as L. kaempferi >A. sachalinensis >P. glehnii. DOY, used to assess phenological effects like leaf morphology, negatively affected the probability of high-intensity mortality occurrence exclusively for L. kaempferi. The median probability of high-intensity mortality occurrence in Hokkaido, calculated from the estimated probabilities across all regions of Hokkaido (encompassing non-forested areas but excluding remote islands), at a 1 km resolution, was 0.37 for L. kaempferi, 0.57 for A. sachalinensis, and 0.41 for P. glehnii under RCP2.6 by the century’s end. These probabilities have decreased in comparison to those observed in 2018–2022. In stark contrast, under RCP8.5, the probabilities soared to 0.91, 0.87, and 0.56, representing an increase of 2.12 times for L. kaempferi, 1.36 times for A. sachalinensis, and 1.14 times for P. glehnii in comparison to 2018–2022. Even the least affected species, P. glehnii, witnessed a increase in mortality probability. This study underscores the importance of forest management and adaptation to climate change.

Characterization of Ralstonia insidiosa C1 isolated from Alpine regions: Capability in polyhydroxyalkanoates degradation and production

This study ventures into the exploration of potential poly-3-hydroxybutyrate (PHB) degradation in alpine environments. PHB-degrading bacteria were identified in both campus soil, representing a residential area, and Mt. Kurodake soil, an alpine region in Hokkaido, Japan. Next-generation sequencing analysis indicated that the campus soil exhibited higher microbial diversity, while Ralstonia insidiosa C1, isolated from Mt. Kurodake soil, displayed the highest proficiency in PHB degradation. R. insidiosa C1 efficiently degraded up to 3% (w/v) of PHB and various films composed of other biopolymers at 14 °C. This bacterium synthesized homopolymers using substrates such as 3-hydroxybutyric acid, sugars, and acetic acid, while also produced copolymers using a mixture of fatty acids. The analysis results confirmed that the biopolymer synthesized by strain C1 using glucose was PHB, with physical properties comparable to commercial products. The unique capabilities of R. insidiosa C1, encompassing both the production and degradation of bioplastics, highlight its potential to establish a novel material circulation model.

Inhibition of blood pressure elevation in GABA‐enriched Hidakakombu fermented with Lactiplantibacillus plantarum 002 protected addition of trehalose

SummaryHidakakombu (Saccharina angustata) is an edible brown alga produced in the Hidaka region of Hokkaido. It is graded at the time of processing, and low‐grade products have a low market value. New ways to utilise Hidakakombu are needed to increase producer profits. In this study, Hidakakombu was fermented with Lactiplantibacillus plantarum 002 to determine its functional properties. Fermentation of the Hidakakombu increased its γ‐aminobutyric acid (GABA) content. The addition of trehalose to L. plantarum 002 in Hidakakombu inhibited the decrease in the number of L. plantarum 002, while maintaining a high level of GABA. L. plantarum 002 in trehalose‐supplemented and fermented Hidakakombu remained viable in simulated gastric juice and grew in simulated intestinal juice. L. plantarum 002‐fermented Hidakakombu has an antihypertensive function that is attributed to GABA. The addition of trehalose protected L. plantarum 002 in fermented Hidakakombu and enhanced freeze‐drying and digestive juice tolerance.

Molecular phylogenetic analysis of Echinococcus multilocularis from horses raised in Canada or Japan, using mitochondrial cytochrome b gene–targeted PCR

Alveolar echinococcosis is a zoonotic disease caused by a larval-stage Echinococcus multilocularis infection. Geographical haplotyping targeting the parasite's mitochondrial cytochrome b (cob) gene has been reported for isolates from definitive and intermediate hosts (wild canids and rodents); however, there are limited reports on strain typing for the dead-end host, the horse, which could act as a sentinel for E. multilocularis. Accordingly, we investigated the diversity of E. multilocularis in isolates obtained from slaughtered Japanese and Canadian horses originating from the Iburi and Hidaka regions in Hokkaido and from Alberta, respectively, with PCR and haplogroup analyses targeting cob gene sequences obtained. Seventy horses were diagnosed with alveolar echinococcosis based on histopathology and cob-gene PCR testing. The E. multilocularis detected in these horses was classified as either an Asian (for Hokkaido-raised horses) or a European (for Alberta-raised horses) haplogroup, based on the obtained cob-gene sequence analysis. In addition, haplotype network analysis revealed that E. multilocularis isolated from Hokkaido-raised horses is highly homologous to Kazakhstan isolates, and E. multilocularis isolated from Alberta-raised horses is highly homologous to Austrian isolates. The results of this study suggest that cob-gene-targeted PCR analysis could be useful for the geographical genetic characterization of E. multilocularis isolated from horses.

Vitamin D concentration in maternal serum during pregnancy: Assessment in Hokkaido in adjunct study of the Japan Environment and Children's Study (JECS).

Vitamin D is an essential nutrient for maintaining blood calcium and phosphorus levels and controlling bone density. Deficiency in it leads to rickets, osteomalacia, osteoporosis, and various other diseases. Recently, it has gained attention for reportedly reducing the risk of COVID-19 severity. However, there are no reports evaluating pregnant women in the Hokkaido region of Japan. This study aims to elucidate the current status of vitamin D levels in pregnant women in the Hokkaido region. This study measured the serum concentrations of Vitamin D2 and D3 in 206 pregnant women participating in the Japan Environment and Children's Study-Hokkaido sub-cohort at the Hokkaido Regional Center. It analyzed the relationship between these concentrations and the months, seasons, and sunshine hours. The mean maternal age was 31.7 ± 4.7 years, and the mean prepregnancy BMI was 21.0 ± 2.5 kg/m2. Only two women have given birth at least once. Regarding sunscreen use, 65 participants (31.6%) responded "often" or "sometimes." Five women used the supplement containing Vitamin D. The value of 25(OH)D2 was above 1 ng/ml in four of them. The average 25(OH)D3 level was 12.1 ng/ml, with a median of 11.0 ng/ml. Four participants (1.9%) had levels below 5 ng/ml. The highest median of 25(OH)D3 was in July, and the lowest was in April. The concentration of 25(OH)D3 was significantly higher in summer than in winter. A correlation was found between 25(OH)D3 and sunshine hours, with 25(OH)D3 concentrations gradually increasing as sunshine hours increase. It was found that almost all pregnant women in Hokkaido were deficient in vitamin D. It is necessary to implement measures to enhance vitamin D levels in pregnant women to safeguard the health of women and fetuses in Hokkaido.

The Proceedings of the 114th Hokkaido Regional Meeting of the Japanese Society of Neurology

The Proceedings of the 114th Hokkaido Regional Meeting of the Japanese Society of Neurology

The Proceedings of the 2023 Hokkaido Regional Post Graduate Education Meeting

The Proceedings of the 2023 Hokkaido Regional Post Graduate Education Meeting

Detecting reed canary grass (Phalaris arundinacea L.) patches from UAV‐based digital surface model images—A case study in a timothy (Phleum pretense L.) meadow field

AbstractAccurate determination of the weed ratio in artificial meadows is critical for efficient pasture renovation. Reed canary grass (Phalaris arundinacea L., RCG) is treated as a troublesome grass in the Hokkaido region of Japan because of its low feed quality and poor palatability in dairy farming. In the present study, we examined a method of identifying the dominant area of RCG in timothy (Phleum pretense L.) meadows by applying the Canny method to unmanned aerial vehicle (UAV)‐based digital surface model (DSM) images. Comparing the actual RCG patches observed in a field survey (50 m quadrats × 4 places) with the predicted patches, the pixel‐based recall and F value were 0.90 and 0.83, respectively. These results demonstrated that the area of RCG can be detected using a simple method without supervised data or deep learning. This study is expected to be utilized in a wide variety of applications using relative height differences.

Phytosociological characteristics of Betula davurica–Quercus crispula forests in Japan based on a comparison with summergreen broad-leaved forests in Northeast Asia

Betula davurica and deciduous Quercus forests are among the principal forest types in Northeast Asia. They are found throughout continental Northeast Asia and in some mountainous regions of Central Honshu and eastern Hokkaido in the Japanese Archipelago. B. davurica–Quercus crispula forests in Japan are significant for understanding the phytogeography of Japan and Northeast Asia. However, their relationships with B. davurica–Quercus mongolica forests in continental Northeast Asia remain poorly understood. We compared the species composition of B. davurica–Q. crispula forests of Japan, with those of Q. crispula dominant forests and B. davurica–Q. mongolica forests using phytosociological methods. The results suggested that B. davurica–Q. crispula forests of Japan had a significant number of species common to the order Lespedezo bicoloris–Quercetalia mongolicae and the class Querco mongolicae–Betuletea davuricae in continental Northeast Asia than in other associations in Japan. Furthermore, our results showed that associations between B. davurica and Q. crispula forests in Central Honshu and Hokkaido are related to different orders in continental Northeast Asia. The relations of the associations between Japan and the continent are considered to have been caused by the environmental similarities, the histories of taxa, and the changes in vegetation distribution.

Modeling hydrological processes under Multi-Model projections of climate change in a cold region of Hokkaido, Japan

Local hydrological systems are highly sensitive to global warming, especially in cold-climate-dominated basins. The integrated climate-hydrological model is a powerful tool to analyze and predict such effects. However, modeling hydrological processes contains considerable uncertainty in cold areas due to the complex dynamics of freeze–thaw cycles and requirements of lot inputs data. Here, we developed a fast and simple approach to modify the soil temperature module in soil and water assessment tool (SWAT) model in a cold region of the Ishikari River basin (IRB), Hokkaido, Japan. Water balance components and sediment yield simulations were explored by the modified SWAT model, outperforming the original SWAT model by PBIAS less than 15 % and NSE higher than 0.60 in monthly streamflow and sediment yield during both calibration (2011–2015) and validation phases (2016–2019). The future prediction was integrated with future climate datasets under four Shared Socioeconomic Pathways (SSP) scenarios (SSP126, SSP245, SSP370, and SSP585) derived from two Global Circulation Models (GCMs), in two future stages (2045–2069 and 2075–2099) with relative to the baseline stage (1990–2014). The varying climate with warmer temperatures (+3.05℃) and less precipitation (-7%) in the future would lead to that evapotranspiration (ET, 67 %) increased. Water yield (WY, −9%), surface runoff (SURQ, −18 %), groundwater flow (GWQ, −10 %), lateral flow (LATQ, −7%), percolation (PERC, −10 %), streamflow (-7%) and sediment yield (-14 %) decreased across the whole basin. However, due to climatic spatial variation, at the subbasin scale, hydrological components (e.g., WY, GWQ, LATQ, and PERC) would increase in the northern region, at the same time, SURQ and ET rise significantly in the central and southern areas. Our findings could offer evidence for future water and soil protection policymaking across the IRB.

Development of an estimation method for accidental hypothermia risk due to cold exposure in disasters triggered by earthquakes and tsunamis

Freezing deaths due to accidental hypothermia cause human casualties in disasters triggered by earthquakes and tsunamis during severe winters. However, until now, scientific estimates for frozen deaths are not included in earthquake damage estimates. The newly published earthquake damage estimation methodology of Japan's Cabinet Office only considers outdoor evacuees as victims of hypothermia. In this study, we developed a method to estimate the number of frozen deaths due to earthquake disasters, using the International Standards Organization's (ISO11079) coldness index to evaluate the “Duration of Limited Exposure” for disaster victims. Furthermore, we applied the proposed function on the damage assumption for the Hokkaido region in Japan and estimated the number of hypothermia sufferers owing to time elapse. This is the first method to estimate the number of frozen deaths owing to time elapse in earthquake disasters, which will be useful for considering measures to reduce the number of frozen deaths.

Geomyces Species (LC374638), a Fungal Endophyte, Promotes the Growth of Honeysuckle (Lonicera caerulea) through Symbiosis

Honeysuckle (Lonicera caerulea), also known as "haskap" in Japan, is a shrub that produces edible berries and inhabits mountainous and wetland areas with harsh environments. In this study, we surveyed the relationship between honeysuckle and the root endophytic fungi. Root samples were collected from the wet land region in Hokkaido, Japan, and subjected to microscopic observation and fungal strain isolation. Totally 47 endophytic fungal strains were isolated from the roots. Inoculation tests showed that a strain of Geomyces sp. promotes the growth of the seedlings and colonizes the epidermal and cortical cells of roots. It suggested that the strain acts as a mycorrhiza-like fungus for the arbuscular mycorrhizal plant. We speculate that honeysuckle establishes a symbiotic relationship with endophytic fungi to overcome acidic and nutrient-deficient environments. This is the first report demonstrating that endophytic ascomycetes promote the growth of host plants belonging to the Caprifoliaceae family.