Biogeographical note on Antarctic microforae: Endemism and cosmopolitanism

This study deals with the biogeography of Antarctic microflora （Antarctica acts as best model to study microbial biogeography） such as cyanobacteria and selected halophiles with special emphasis on Halomonas variabilis and Bacillus licheniformis.Halophiles are known to be resistant not only to salt stress,but also to extreme temperature,pressure,and aridity and they are capable of surviving in harsh environments such as polar regions,deep-sea habitats,and deserts.Many microbes are known to be resistant to hostile environmental conditions,and are capable of surviving in harsh environments.Our group has isolated 444 strains belonging to 28 genera of halophiles from various environments around the world.The 16S rRNA gene sequences revealed that many of the isolated strains from geographically distant habitats having different environmental conditions,were closely related to each other,with some strains possessing 100％ identical sequences.Organisms possessing survival mechanism such as spore formation are usually ubiquitous.The genus Halomonas is represented by potentially endemic strains and the ubiquitous H.variabilis,while spore-forming B.licheniformis showed cosmopolitan distribution.One potentially endemic （moderate endemicity that is regional and/or continental distribution） strain was reported from Syowa station,East Antarctica,and Mario Zucchelli station,West Antarctica,which are geographically separated by 3000 km.Moreover,15 strains having 100％ similarity with B.licheniformis were considered cosmopolitans.The results of this work provide support for the middle-ground model that some microbes have moderate endemicity and others have cosmopolitan distribution.These results will contribute to a greater understanding of microbial biogeography with special emphasis on Antarctica.

Throughfall and stemflow chemical dynamics of Satoyama, a traditional secondary forest system under threat in Japan

The term 'Satoyama' refers to traditional and unique secondary forests in Japan that occupy intermediate zones between villages ('sato') and hills or mountains ('yama'). Satoyama landscapes help sustain ecosystem services and the diversity of secondary natural environments. As Japan relies more heavily on foreign timber imports, the traditional role of Satoyama in providing forest products has diminished, and this has led to their abandonment and poor management. The chemical behavior of cations, anions, and dissolved organic matter in throughfall and stemflow from one such threatened Satoyama system in central Japan was investigated. From autumn to winter, the atmospheric deposition of sulfates and nitrates was 2.5–6.0 times higher compared to the amounts in summer due to the intrusion of air masses from the Asian continent. The dissolved organic matter in the throughfall and stemflow was composed mainly of humic substances and protein derivatives. The deposition fluxes of dissolved organic carbon from throughfall (7.31–10.1 g m^(−2) a^(−1)) and stemflow (1.79–3.84 g m^(−2) a^(−1)) in this study were within ranges seen in temperate forests in previous studies. The deposition flux of sulfates was low compared to that in other forest types because canopy interaction was lower, suggesting higher canopy openness than in primary forests. If a shift from a mixed species Satoyama forest to a conifer-dominated forest occurs after the mass mortality of oak, the deposition flux of dissolved organic carbon and K^(+) might decrease by 33% and 62%, respectively, while NO_(3)^(−) might increase by 20%. In the near future, the degradation of Satoyama landscapes might change the levels of dissolved organic carbon and nitrogen loads, resulting in imbalances in river-ocean linkages affecting forested catchments and aquatic ecosystems in Japan.