To clarify the floristic composition of paddy field communities in tropical Asia, phytosociological research was conducted in Yunnan Province of China. Relevés were then compared with relevés in Japan, South Korea and North Korea in East Asia, and relevés on the tropical islands of Hainan, China, and Sumatra, Indonesia. The results showed that the relevés in Yunnan Province and on Hainan Island, as well as a few relevés in Okinawa Prefecture could be described by the new association Ludwigio adscendentis - Monochorietum vaginalis. This association was divided into 5 subassociation. The association is belonged to Oryzo - Echinochloion oryzoidis, Cypero - Echinochloetalia oryzoidis, Oryzetea sativae as upper vegetation unit.

View full abstract

Taxillus yadoriki （Loranthaceae） is a hemiparasitic plant species that attaches to the stems and branches of trees. There are many host trees of T. yadoriki in a park in Miyazaki City, Miyazaki Prefecture. In this park, we surveyed the species, size, and degree of debilitation of these host trees and the foliar cover of T. yadoriki in order to examine the host specificity of T. yadoriki and the effects of its parasitism on trees. In addition, we resurveyed the degree of debilitation after 4 to 5 years. A total of 422 host trees from 27 species were observed in the park. This study and a literature survey revealed that there were at least 67 species （29 families） of the host trees of T. yadoriki in Japan. Lithocarpus edulis was the most common host tree, comprising 62.9% of all host trees. The frequency that L. edulis trees were infected by T. yadoriki was higher in taller trees and canopy trees. An analysis of host specificity using Jacob’s selectivity index suggested that T. yadoriki had a preference for the tree species L. edulis, Quercus serrata, Cryptomeria japonica, and Eurya japonica var. japonica. The degree of debilitation of the host trees was graded on a scale of one to five. Most host trees （86.7%） were debilitated, and the debilitation grade for L. edulis had a highly positive correlation with the foliar cover of T. yadoriki. Therefore, it was determined that T. yadoriki induced the tree debilitation. A resurvey indicated that T. yadoriki killed host trees and that L. edulis was susceptible to death by parasitism.

View full abstract

Japanese temperate conifers, Picea sect. Picea and Pinus koraiensis, are rare at present in Japan. Previous palaeobotanical studies report on macrofossil data for those conifers obtained throughout Japan at the Last Glacial. These results suggest that those conifers have experienced unique distribution history since the Last Glacial. We surveyed the distribution of a Picea koraiensis （Picea sect. Picea）-Pinus koraiensis-deciduous-broadleaved mixed forest along a soil moisture gradient in the upper stream of the River Ussuri in the Russian Far East, to reconstruct the reliable distribution history of the Japanese Picea sect. Picea and Pinus koraiensis. The two conifers are principally distributed on the mesic and moist sites with deciduous broad leaved trees such as Acer mono, Tilia amurensis, Fraxinus mandshurica and Ulmus japonica. They appear with a few amount on the dry sites, where xeric species such as Quercus mongolica, Betula davurica prevail. The survey results show that 1） the Japanese Picea sect. Picea and Pinus koraiensis are ecologically temperate mesic - moist type in nature, 2） actually no continental type of coniferous forests consisting of the two species occurs in the Russian Far East as well as in central Japan at present. The most prominent feature of the tree distribution at the Last Glacial in central Japan was that the Japanese Picea sect. Picea and Pinus koraiensis made the mixed forest with deciduous broadleaved trees in the lowland and hilly areas on mesic and moist sites. The abundant outcrops of macrofossils of the Picea sect. Picea and Pinus koraiensis in the Last Glacial throughout Japan indicate that at the Last Glacial they prevailed on the mesic and moist sites which preserved macrofossils well.

View full abstract