Rheophytic Adaptation of Eurya Japonica Thunb. (Ternstroemiaceae)

Plants along rivers have narrow leaves to avoid the stress caused by the river’s flow during flooding. Plants that have undergone such morphological leaf modifications to adapt to rivers are called rheophytes. Some populations of Eurya japonica Thunb. (Ternstroemiaceae) were grown on riversides so that the comparative morphology and anatomy of leaves between riverside and inland (control) populations could be examined to confirm their rheophytic speciation. Our morphological and anatomical analyses revealed that the leaf of E. japonica in the riverside populations was significantly smaller than that of the inland populations due to the decreased number of cells; therefore, the pattern of rheophytic differentiation in riversides was not the stenophyllization but the miniaturization of the leaf. Moreover, our results indicated that this species in the riverside populations had thicker leaves and higher density of stomata than those of inland populations, suggesting that E. japonica had been morphologically modified in response to the light and water environments along the river.

New genus of dikraneurine leafhopper (Hemiptera: Cicadellidae: Typhlocybinae) from Japan, with description of two new species

A new genus, Stictotettix gen. nov. and two new species of Dikraneurini, S. cleyerae sp. nov. and S. morishimai sp. nov., are described and illustrated, based on the specimens from Japan. This new genus is unique in the male genital features of the aedeagal atrium. The two new species live on pentaphylacacean trees, Cleyera japonica and Eurya japonica, respectively.

Changes in understory species occurrence of a secondary broadleaved forest after mass mortality of oak trees under deer foraging pressure

The epidemic of mass mortality of oak trees by Japanese oak wilt has affected secondary deciduous broadleaved forests that have been used as coppices in Japan. The dieback of oak trees formed gaps in the crown that would be expected to enhance the regeneration of shade-intolerant pioneer species. However, foraging by sika deerCervus nipponhas also affected forest vegetation, and the compound effects of both on forest regeneration should be considered when they simultaneously occur. A field study was conducted in Kyôto City, Japan to investigate how these compound effects affected the vegetation of the understory layer of these forests. The presence/absence of seedlings and saplings was observed for 200 quadrats sized 5 m ×5 m for each species in 1992, before the mass mortality and deer encroachment, and in 2014 after these effects. A hierarchical Bayesian model was constructed to explain the occurrence, survival, and colonization of each species with their responses to the gaps that were created, expanded, or affected by the mass mortality ofQuercus serratatrees. The species that occurred most frequently in 1992,Eurya japonica,Quercus glauca, andCleyera japonica, also had the highest survival probabilities. Deer-unpalatable species such asSymplocos prunifoliaandTriadica sebiferahad higher colonization rates in the gaps, while the deer-palatable speciesAucuba japonicahad the smallest survival probability. The gaps thus promoted the colonization of deer-unpalatable plant species such asSymplocos prunifoliaandTriadica sebifera. In the future, such deer-unpalatable species may dominate gaps that were created, expanded, or affected by the mass mortality of oak trees.

Changes in understory species occurrence of a secondary broadleaved forest after mass mortality of oak trees under deer foraging pressure

The epidemic of mass mortality of oak trees has affected secondary deciduous broadleaved forests that have been used as coppices in Japan. The dieback of oak trees formed gaps in the crown that would be expected to enhance the regeneration of shade-intolerant pioneer species. However, foraging by sika deer Cervus nippon has also affected forest vegetation, and the compound effects of both on forest regeneration should be considered when they simultaneously occur. A field study was conducted in Kyôto City, Japan, to investigate how these compound effects affected the vegetation of the understory layer of such a forest. The presence/absence of seedlings and saplings was observed for 200 quadrats sized 5 m × 5 m for each species in 1992, before the mass mortality and deer encroachment, and in 2014 after these effects. A hierarchical Bayesian model was constructed to explain the occurrence, survival, and colonization of each species with their responses to the gaps created or affected by the mass mortality of oak trees. The species that occurred most frequently in 1992, Eurya japonica, Quercus glauca, and Cleyera japonica, also had the highest survival probability. Deer-unpalatable species such as Symplocos prunifolia and Triadica sebifera had higher colonization rates in the gaps, while the deer-palatable species Aucuba japonica had the smallest survival probability. The gaps thus resulted in promoting the colonization of deer-unpalatable plant species such as Symplocos prunifolia and Triadica sebifera. It might be forecasted that such deer-unpalatable species will dominate the gaps created or affected by the mass mortality of oak trees.

Changes in understory species occurrence of a secondary broadleaved forest after mass mortality of oak trees under deer foraging pressure

The epidemic of mass mortality of oak trees has affected secondary deciduous broadleaved forests that have been used as coppices in Japan. The dieback of oak trees formed gaps in the crown that would be expected to enhance the regeneration of shade-intolerant pioneer species. However, foraging by sika deer Cervus nippon has also affected forest vegetation, and the compound effects of both on forest regeneration should be considered when they simultaneously occur. A field study was conducted in Kyôto City, Japan, to investigate how these compound effects affected the vegetation of the understory layer of such a forest. The presence/absence of seedlings and saplings was observed for 200 quadrats sized 5 m × 5 m for each species in 1992, before the mass mortality and deer encroachment, and in 2014 after these effects. A hierarchical Bayesian model was constructed to explain the occurrence, survival, and colonization of each species with their responses to the gaps created or affected by the mass mortality of oak trees. The species that occurred most frequently in 1992, Eurya japonica, Quercus glauca, and Cleyera japonica, also had the highest survival probability. Deer-unpalatable species such as Symplocos prunifolia and Triadica sebifera had higher colonization rates in the gaps, while the deer-palatable species Aucuba japonica had the smallest survival probability. The gaps thus resulted in promoting the colonization of deer-unpalatable plant species such as Symplocos prunifolia and Triadica sebifera. It might be forecasted that such deer-unpalatable species will dominate the gaps created or affected by the mass mortality of oak trees.