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Hasebe N.,Kanazawa University | Hasebe N.,Korea Institute of Geoscience and Mineral Resources | Nakano Y.,Kanazawa University | Miyamoto H.,Kanazawa University | And 4 more authors.
Island Arc | Year: 2016

The Hakusan volcano, central Japan, is located in a region where two subducting plates (the Pacific Plate and the Philippine Sea Plate) overlap near the junction of four plates adjacent to the Japanese Islands (the Pacific Plate, the Philippine Sea Plate, the Eurasia Plate, and the North American Plate). The Hakusan volcano consists of products from four major volcanic episodes: Kagamuro, Ko-hakusan, and Shin-Hakusan I and II. To date the eruption events of the Hakusan volcano we applied thermoluminescence and fission track methods. 238U(234U)-230Th disequilibrium and 206Pb/238U methods were applied to date the zircon crystallization ages for estimating the magma residence time before the eruptions. The eruption ages we obtained are ca 250 ka for Kagamuro, ca 100 ka and ca 60 ka for Ko-Hakusan, ca 50 ka for Shin-Hakusan I, and <10 ka for Shin-Hakusan II. They are concordant with previous reports based on K-Ar dating. Some of the pyroclastic rocks, possibly originating from Shin-Hakusan II activities, are dated to be ca 36 ka or 50 ka, and belong to the Shin-Hakusan I activity. The zircon crystallization ages show several clusters prior to eruption. The magma residence time was estimated for each volcanic activity by comparing the major crystallization events and eruption ages, and we found a gradual decrease from ca. 500 ky for the Kagamuro activity to ca. 5 ky for the Shin-Hakusan II activity. This decrease in residence time may be responsible for the decrease in volume of erupted material estimated from the current topography of the region. The scale of volcanic activity, which was deduced from the number of crystallized zircons, is more or less constant throughout the Hakusan volcanic activity. Therefore, the decrease in magma residence time is most likely the result of stress field change. © 2016 John Wiley & Sons Australia, Ltd.


Ohwaki A.,Kanazawa University | Ogawa H.,Hakusan Nature Conservation Center | Taketani K.,Ishikawa Insect Museum | Tomisawa A.,Ishikawa Insect Museum
Landscape and Urban Planning | Year: 2014

To examine the effects of cultivated field abandonment on butterfly assemblages, we investigated butterfly assemblages in seven local settlements with varying degrees of abandonment of cultivated fields. We hypothesized that species with specialist characteristics (univoltine and oligophagous species) would increase with an increasing proportion of old abandoned fields (50-80% of these fields had been abandoned for approximately 30 years) and that species that utilized annual plants would increase with an increasing proportion of recently abandoned fields (abandoned for one to two years). Species richness and the abundance of univoltine, oligophagous, and non-annual feeding species increased with increasing proportions of old abandoned fields, whereas those of multivoltine, polyphagous, and annual feeding species decreased or remain stable. Species that utilized annual plants did not respond to the amount of recently abandoned fields. Redundancy analyses showed that the proportions of old and recently abandoned fields affected butterfly assemblages but that other uncontrolled factors, such as road density and the distance to the continuous forests, did not affect butterfly assemblages. Our results showed that abandoned cultivated fields are beneficial to some specialist butterflies that are sensitive to the simplification of landscapes and can be an option for increasing biodiversity, particularly in simplified agricultural landscapes. Further research is required to reveal factors affecting vegetation types in abandoned cultivated fields, to determine the relative effects of local compared with landscape factors regulating butterfly assemblages, and to examine the role of abandoned cultivated fields compared with other semi-natural vegetation for conserving biodiversity in agricultural landscapes. © 2014 Elsevier B.V.


Ishibashi Y.,Japan Forestry and Forest Products Research Institute | Oi T.,Japan Forestry and Forest Products Research Institute | Oi T.,Ishikawa Prefectural University | Arimoto I.,Hakusan Nature Conservation Center | And 7 more authors.
Conservation Genetics | Year: 2016

In Japan, the black bear, Ursus thibetanus, is distributed on Honshu and Shikoku Islands. Most populations in western Japan declined considerably during the twentieth century, but a few populations are now rebounding due to conservation efforts. Here, we examined the sequence variation in the second exon of the major histocompatibility complex class II DQB gene (270 bp), which is critical for pathogen recognition. We measured variation within six populations in western Japan, including two threatened populations in the Chugoku region on Honshu and one on Shikoku. Eight sequence variants were observed among the examined bears (n = 417), and two to eight variants were retained within populations. Our samples, collected in 2001–2013, retained a smaller number of sequence variants in each population compared with the allelic diversity in an earlier study that examined the same gene and used samples collected mainly during the last century. Many rare variants that were observed previously and may have been maintained by balancing selection have disappeared from recent populations. Although the earlier study suggested a loss of genetic diversity in western Japan, the present study shows that further loss of rare variants has occurred, probably due to genetic drift during the end of the last century. © 2016 Springer Science+Business Media Dordrecht


Sano S.,Osaka Prefecture University | Sano S.,Fukui Prefectural Government | Nakayama Y.,Osaka Prefecture University | Ohigashi K.,Japan National Institute for Agro - Environmental Sciences | And 2 more authors.
Weed Biology and Management | Year: 2016

In the subalpine zone on Mt. Hakusan, Japan, Plantago asiatica, an alien plant, and Plantago hakusanensis, a native alpine species, grow sympatrically along with their putative hybrids. Here, their flowering behavior, which affects the frequency of hybridization and the colonizing ability of P. asiatica and its hybrids, is described. The flowering behavior of each species and of two F1 hybrids from different seed parents was determined based on the position of the flower in the inflorescence by using a generalized linear mixed model. The percentage fruit set of individually bagged inflorescences was calculated to corroborate the assumptions of the opportunities for self-pollination. All the flowers were protogynous; however, many P. asiatica anthers dehisced before browning of the stigma in the flower and the sex presentations in the inflorescence were asynchronous. The percentage of fruit set was high. Consequently, P. asiatica has the opportunity for self-pollination within the flower and in the inflorescence. In contrast, the P. hakusanensis anthers dehisced after browning of the stigma in the flower; their sex presentation was synchronous in the inflorescence, showing negligible opportunities for self-pollination, and the fruit set was low. Accordingly, in the field, P. hakusanensis might require pollination among the inflorescences for seed production and be actively outcrossed, while P. asiatica is able to outcross in the early flowering phase. Therefore, P. asiatica and P. hakusanensis have opportunities for hybridization. The F1 hybrids exhibited intermediate flowering behavior and produced fruits, demonstrating the potential to reproduce by selfing. © 2016 Weed Science Society of Japan


Imajo K.,Human and Nature Ikeda | Esaki K.,Hakusan Nature Conservation Center
Nihon Ringakkai Shi/Journal of the Japanese Forestry Society | Year: 2013

We developed a new method to catch adults of the oak borer Platypus quercivorus, the vector of the Japanese oak wilt disease, by covering the entry holes bored on the trunk surface with a wetted face towel. We set towels on the base of three trees attacked by the borer from October to December and caught 13.3 adults per square meter of towel per day per tree. We observed that adults bored new tunnels into the towels extending from their entry holes and were trapped. The sex ratio was extremely biased to males and the rate of the male parents to all male adults captured in December was 24.0%. These results suggest that the reproductive success of P. quercivorus can be reduced by extracting male parents before winter with towels.


Nogami T.,Hakusan Nature Conservation Center | Yoshimoto A.,Hakusan Nature Conservation Center | Nakamura K.,Ishikawa Nature Guide Association | Kodani J.,Ishikawa Agricultural and Forestry Research Center | Nozaki E.,Ishikawa Prefecture
Nihon Ringakkai Shi/Journal of the Japanese Forestry Society | Year: 2013

For the purpose of predicting the infest of the Asiatic black bear, Ishikawa Prefectural Government conducted the survey for the prospective yield of the masts of the three Fagaceae species. The survey has been entrusted to the Ishikawa Nature Guide Association, which is a volunteers association for guide service of nature. As a result of questionnaire, most of the members who participated in the investigation answered that they were able to get a greater understanding about the relation between beechnut production and bear infest. And it became clear that this experience was also helpful to improve their normal activities of nature interpretation. Thus, to involve nature guides in such investigation activities is considered to contribute to promote the proper knowledge of bear infest issue to the public secondarily. In addition, when it entrusts a volunteer group, it is important to adopt not only the technical methods to conduct easily the investigation and open the workshop for investigations, but also to choose the investigation sites with an expert.


Mizutani M.,Fukui Nature Conservation Center | Nakajima H.,Forestry Research Institute | Kodani J.,Ishikawa Agricultural and Forestry Research Center | Nogami T.,Hakusan Nature Conservation Center | And 2 more authors.
Nihon Ringakkai Shi/Journal of the Japanese Forestry Society | Year: 2013

The relationship between the acorn crops of trees belonging to the Fagaceae family and the mass intrusion of Asiatic black bears (Ursus thibetanus) into the residential areas of the Hokuriku region were investigated based on an acorn crop monitoring survey conducted over a 7-year period, from 2005 to 2011, in the Toyama, Ishikawa, and Fukui Prefectures of Japan. Large fluctuations were observed in the annual acorn production of both Fagus crenata and Quercus crispula located in the high-altitude areas of all three prefectures. In particular, extremely poor yields of acorns were noted for 2006 and 2010, which coincided with the mass intrusion of bears into the residential areas. In contrast, little fluctuation was observed in the annual acorn production of Q. serrata distributed in low-altitude areas, and there were no incidents of years with extremely poor yields. These results infer that food shortages, due to simultaneous poor crops of F. crenata and Q. crispula in the mountainous areas of Hokuriku region, triggered the mass intrusions of bears into residential areas. Since the fluctuations in the annual acorn production of these key species were synchronized across a wide geographic area, a comparative analysis and coordinated survey of the acorn crop monitoring of each neighboring prefecture should result in an effective as well as accurate forecast of the acorn yields and therefore of bear intrusions.

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