Factors affecting the dynamics of the population of Fagus crenata in the Takakuma Mountains, the southern limit of its distribution area     

Hiromi Mizunaga  Shizuo Sako  Yuri Nakao  Yoshitaka Shimono 《Journal of Forest Research》2005,10(6):481-486

The refugee population of Fagus crenata in the Takakuma Mountains, Kyushu, Japan, represents the southern limit of this species' distribution area. Because this population is the most exposed to the global warming effect, records of this population are likely to provide useful information on the response of this species to global warming. The aim of this study was to record the present status of this valuable population, enabling judgment of its sustainability. The density of successive F. crenata trees and saplings was low regardless of the coverage of dwarf bamboo. Moreover, the proportion of empty nuts observed was considerably high, suggesting to be the likely major factor limiting recruitment of saplings or successors in this population. Radial growth of F. crenata was shown to have been decreasing for the past 50 years, and there was a significantly negative correlation with the warmth index. The decreasing growth rate and poor regenerative ability caused by the high proportion of empty nuts suggest the possibility that this population will degrade further in the future, possibly being replaced by shrubs and small tree species.  相似文献   

Nitrogen use by <Emphasis Type="Italic">Pinus densiflora</Emphasis> trees growing on a Mt. Fuji lava flow     

Hiromi?TanabeEmail author  Yoshiko?Abe  Takashi?Nakano 《Journal of Forest Research》2004,9(3):249-254

To quantify the nitrogen (N) use by Pinus densiflora trees growing on an infertile lava surface, N pools, N requirement and N uptake through fine roots and N deposition from the atmosphere were estimated. The N requirement and the N uptake of fine roots were 55.5kgNha^–1year^–1 and 39.7kgNha^–1, respectively. Thus, the ratio of N uptake to N requirement of the fine roots was 71.5%. Including fine-root contribution, the total N requirement of the P. densiflora trees was 98.6kgNha^–1year^–1, and the total N uptake was 64.2kgNha^–1year^–1. Thus, the N uptake of the P. densiflora trees was 64.1% of the N requirement, indicating that P. densiflora trees growing on an infertile lava surface obtain some of their N from below-ground organic material layers every year and the contribution of N storage in trees for their growth is not any higher than indicated in previous reports that excluded fine-roots contribution. The wet N deposition of our research forest was only 5.8% of the N requirement of the P. densiflora trees and only 8.9% of the N uptake. Movement of the below-ground organic material layer N concentrations in the F- and L-layers coincides with needle development and fine-root growth, suggesting the possibility that P. densiflora trees extract N from the organic N of those layers for growth.  相似文献   

Effects of topography and management history on natural forest recovery in abandoned forest after clear-cutting in Miyazaki, Japan     

Hiromi Yamagawa  Satoshi Ito  Yasushi Mitsuda  Kazuro Fukuzato 《Journal of Forest Research》2006,11(2):99-106

We investigated factors limiting the recovery of natural forest in former large-scale conifer plantations abandoned after clear-cutting in southwestern Japan. We analyzed forest recovery status (“recovered” sites covered by evergreen broad-leaved trees, and “unrecovered” sites covered by pioneer community or nonvegetated sites) using aerial photographs and field survey. We applied logistic regression analyses to evaluate the effects of topography, construction of harvesting roads, distance from remnant forest, stand condition before clear-cutting, and prior land-use history on forest recovery. Human factors, i.e., land use and clear-cutting age, were found to affect to forest recovery more than environmental factors such as topography. Harvesting roads had the strongest negative impact on forest recovery. Forest recovery after clear-cutting of young sugi plantations also took longer than after clear-cutting of old sugi plantations or evergreen broad-leaved forests. Furthermore, areas formerly utilized as meadows recovered less successfully than those that had been managed as coppices. The influences of these factors were thought to be promoted by the advance reproduction as the regeneration sources for forest recovery. The influence of stand age before logging suggested an effect of thinning, which might alter the abundance of advanced reproduction in the understory. However, distance from remnant forest appeared to be less important. An influence of topography was also detected, but this could be partly explained by the existence of advance reproduction in the understory in certain topographic positions. Thus, our analysis suggests that regeneration sources originating from advanced reproduction in plantations play a significant role for the recovery of natural forest after clear-cutting.  相似文献   

Phylogenetic relationship of Pasteurella pneumotropica isolates from laboratory rodents based on 16S rDNA sequence     

Sasaki H  Kawamoto E  Ueshiba H  Amao H  Sawada T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(6):639-641

A 1344 bp fragment of the 16S ribosomal DNA (rDNA) sequence was used to determine the genetic relationship of Pasteurella pneumotropica isolates from laboratory rodents. A total of 30 nucleotide sequences of P. pneumotropica, including 24 wild strains, 3 reference strains, and 3 nucleotide sequences deposited in GenBank, were examined for heterogeneity of their 16S rDNA sequences. Phylogenetic analysis based on 16S rDNA sequence discriminated 5 types of branching lineages. Of these 5 types, 3 types had significant associations with mice or rats, and 2 had significant associations with the beta-hemolytic phenotype. These results suggest that 16S rDNA sequencing of P. pneumotropica isolates demonstrates genetic heterogeneity and phylogenetic discrimination in terms of their hemolytic phenotype and host associations.  相似文献   

A case of protein-losing enteropathy treated with methotrexate in a dog     

Yuki M  Sugimoto N  Takahashi K  Otsuka H  Nishii N  Suzuki K  Yamagami T  Ito H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(4):397-399

A 9-year-old female Pug was presented to us with chronic diarrhea. Hematologic findings indicated severe hypoproteinemia and hypoalbuminemia, and endoscopy revealed severe edema of the duodenal mucosa. Based on these results and on additional histopathological findings, we made a diagnosis of protein-losing enteropathy caused by lymphocytic-plasmacytic enteritis with lymphangiectasia. The dog was initially treated with prednisolone and cyclosporine. This treatment regimen was not effective. However, when methotrexate was substituted for cyclosporine, progress was obtained and the diagnosis was confirmed.  相似文献   

Interspecific variation in leaf water use associated with drought tolerance in four emergent dipterocarp species of a tropical rain forest in Borneo     

Toru Hiromi  Tomoaki Ichie  Tanaka Kenzo  Ikuo Ninomiya 《Journal of Forest Research》2012,17(4):369-377

By use of tree-tower and canopy-crane systems we studied variations in the water use, including transpiration, stomatal conductance, and leaf water potential, of the uppermost sun-exposed canopy leaves of four emergent dipterocarp species in an aseasonal tropical rain forest in Sarawak, Malaysia. Midday depression in stomatal conductance and leaf water potential was observed in all the species studied. Interspecific differences were clearly observed in the maxima of transpiration rates and stomatal conductance and the minima of leaf water potential among the four dipterocarp species. These interspecific variations were closely related to wood density and to factors affecting ecological patterns of distribution. Specifically, Shorea parvifolia and S. smithiana, both of which have a relatively low wood density for Dipterocarpaceae and are found on clay-rich soil, had a high transpiration rate in the daytime but had a large midday depression and a low leaf water potential. In contrast, Dryobalanops aromatica, which has a high wood density and is found in sandy soil areas, consumed less water even during the daytime. Dipterocarpus pachyphyllus, which has a high wood density and is found on clay-rich soil, stood intermediate between Shorea and D. aromatica in leaf water use. The two Shorea species had higher mortality than the others during the severe drought associated with El Ni?o in 1998, so daily pattern of leaf water use in each dipterocarp species might be correlated with its susceptibility to unusual drought events.  相似文献   

Intestinal Tritrichomonas suis (=T. foetus) infection in Japanese cats     

Doi J  Hirota J  Morita A  Fukushima K  Kamijyo H  Ohta H  Yamasaki M  Takahashi T  Katakura K  Oku Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(4):413-417

Tritrichomonas suis (=T. foetus) has recently been reported to be a causative agent of chronic large-bowel diarrhea in cats. While the disease was previously attributed to Pentatrichomonas hominis, the etiologic agent for feline trichomonal diarrhea was identified as T. suis. Although feline trichomonosis due to T. suis has been reported at prevalences ranging from 14 to 31% in Europe and the U.S., no reports of the pathogen have been published to date in Japan. In 2008, however, we encountered a case of feline trichomonosis at the Veterinary Teaching Hospital of Hokkaido University. The parasite was identified as T. suis by nested PCR amplification of partial internal transcribed spacer region 1 and 5.8S ribosomal RNA gene sequences with T. suis-specific primers and DNA sequencing of the amplified products. We then conducted surveys for feline trichomonosis in three different animal hospitals using either cultivation and/or PCR-based assays. The results revealed that 13 of 147 samples (8.8%) were positive for T. suis, and that 5 of the 13 infected cats, which ranged between 1 month and 7.5 years-old, showed chronic diarrhea. Seven of the infected cats were purebred and 6 were mixed breed. These findings suggested that feline trichomonosis is prevalent in Japan, and that T. suis may play a role as a causative agent of feline chronic diarrhea.  相似文献   

Downregulation of hepatic cytochrome P450 3A in mice infected with Babesia microti     

Shimamoto Y  Sasaki M  Ikadai H  Ishizuka M  Yokoyama N  Igarashi I  Hoshi F  Kitamura H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(2):241-245

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Development of in vitro atovaquone-resistant Babesia gibsoni with a single-nucleotide polymorphism in cytb     

Iguchi A  Matsuu A  Ikadai H  Talukder MH  Hikasa Y 《Veterinary parasitology》2012,185(2-4):145-150

An atovaquone (ATV)-resistant Babesia gibsoni was developed by in vitro exposure of uncloned wild type (WT) B. gibsoni to 800 nM ATV for 6 days. Sequence analysis of mitochondrial genes showed a single-nucleotide polymorphism (SNP) at cytb nt363 (G to T) that resulted in the substitution of methionine with isoleucine (M121I), which is one of the SNPs reported in a previous in vivo study. 363T or 363G allele-specific real-time polymerase chain reaction (PCR) revealed that an M121I variant was present in over 99% of the ATV-resistant population. As neither ATV resistance nor gene polymorphisms appeared in the B. gibsoni WT sibling clones, the expression of ATV resistance in this study was suspected to be because of selective multiplication of the B. gibsoni M121I variant. This ATV-resistant B. gibsoni displayed the same sensitivity as the WT B. gibsoni against 5 other drugs, including diminazene aceturate, azithromycin, doxycycline, clindamycin, and proguanil. This is the first report on the in vitro establishment of an ATV-resistant B. gibsoni with gene polymorphisms.  相似文献   

The influence and impact of tsunamis on the microorganism assembly of Nagatsura-Ura Lagoon,Miyagi, northeastern Japan     

Okumura  Yutaka  Matsuoka  Hiromi  Arakawa  Hisayuki  Tokanai  Fuyuki  Suzuki  Atsushi  Irizuki  Toshiaki  Kajita  Hiroto  Hara  Motoyuki 《Fisheries Science》2021,87(1):121-130

Fisheries Science - Two sediment cores were collected from two sites in Nagatsura-Ura Lagoon, the mouth of which was destroyed in the 2011 Tohoku-oki tsunami. Although sediment conditions differed...  相似文献