ECOLOGICAL STUDIES ON THE EPIPETRIC PLANT COMMUNITY

Abstract

An investigation was made in the precincts of Kasuga shrine in Nara City to ascertain the floristic composition in relation to the environment of the epipetric plant community growing on Ishidoro (the stone-lantern pillars) there. 1. The epipetric plant communities found within the area are integrated into Hypneto-Hedwigietum with the following characteristic species ; Hedwigia albicans (WEB.) LINDB., Hypnum plumaeforme WILS., H. plumaeforme var. minus BROTH. and Grimmia pilifera PALIS. This plant-union consists of the following seven societies ; Cladonia gracilis var. chordalis society, Parmelia tincto ; uma soc., Hedwigia albicans soc., Hypnum plumaeforme soc., H. plumaeforme var. minus soc., Chrysocladium retrorsum soc. and Meteorium helmintocladulum society. 2. It may be considered that Hedwigia albicans soc., Hypnum plumaeforme soc. and H. plumaeforme var. minus soc. exhibit the features of the genuine-facies of the epipetric plant communities found in the area. The community dominated by Hedwigia alticans (WEB.) LINDB. shows better development in fairly sunny habitats, while that of Hypnum plumaeforme var. minus soc. does so in the shady habitats overhung by the crown of evergreen trees close by. 3. Cladonia gracilis var, chordalis soc. and Parmelia tinctorum soc. may be considered as facies which occur mostly in an open and sunny hibitat. The occurrence of Chrysocladium retrorsum soc. and Meteorium helmintocladulum soc. is confined to the most shady habitats where the trees are overshadowing all the time. 4. The degree of overshadowing by the trees nearby and the changes of environmental factors, such as, air temperature, saturation deficit and illumination, at five stonelantern pillars which were occupied by different communities, were respectively recorded on March 15,1956. From the obtained data, considerable differences of microclimatic factors, i. e. saturation deficit and illumination, are clearly observed among respective habitats according to the degree of overshadowing of the trees close by. It may be considered that the degree of overshadowing by the trees plays an important role on the development and the distribution of the epipetric plant community.