In the Kiyosumi area of the University of Tokyo Chiba Forest, located in the southeast of the Boso Peninsula, we analyzed the relationship among Sika deer (Cervus nippon) population density, damage caused by Sika deer to planted Sugi (Cryptomeria japonica) and Hinoki (Chamaecyparis obtusa) , and the mortality and height growth of Sugi and Hinoki. Damage to planted Sugi varied extensively from 0% to 100%, whereas that to Hinoki was greater than approximately 60% or less than approximately 10%. In plots where damage was continuously high and cumulative damage in the 4^th year had increased above 300%, the cumulative mortality of planted Sugi increased until the 5^th year, whereas that of planted Hinoki, with the exception of one plot, remained low. In plots where damage was continuously high, the Sugi trees appeared to be able to grow taller than the height where deer can eat, although their height was approximately half that in plots where damage was low and cumulative damage in the 3^rd year was less than 200%. Furthermore, in some Hinoki plots in which damage was continuously high, the trees showed almost no growth in height.

View full abstract

At Cape Shiretoko, problems of a decrease in Sasa owing to the higher density of sika deer (C. nippon yesoensis H.) is becoming serious. Also, marked decreases in specific kinds of trees, in seedings of trees and in shore plant communities containing the endangered species occur by their browsing or bark stripping. In addition, problem of soil erosion becomes also serious. Therefore, density manipulation of wintering sika deer herd was carried out in 2007, and it required us to develop the vegetation indexes that can evaluate the effect of human interventions or that can be indicating the start or the end of interventions. In this study, we investigated the biomass of Poaceae, the size structure of C. vurgare and the coverage and height of S. cannabifolius at the inside and outside of the fences. We also investigated the biomass of Poaceae, S. senanensis at Cape Shiretoko, and the leaves of forest vegetation around Cape Shiretoko grassland. As the results, after the density manipulation started, the biomass of Poaceae showed increasing, C. vulgare decreased promptly, coverage of S. senanensis showed increasing. We concluded that these could be the indexes in short term, and that height of S. senanensis could be used as the index in middle or long term because it showed a poor growth after the density manipulation started. Furthermore, this study also indicated that the biomass of leaves at every height of trees can be the indexes for long or short term, since biomass of leaves increased differently corresponding to each height.

View full abstract

Since the overabundance of Sika deer has potential to cause irreversible shift of ecosystem, proactive management from early stage would be desirable. To conduct proactive management under the limitation of resource in terms of funds and labors for biological conservation, it is necessary to specify the area with high priority to conserve regional flora, and incorporate it into the management plan. We used 198 phytosociological releves derived from Chichibu-tama-kai National Park, and divided all recorded species into 4 groups by 2 criteria: “decreased species in the area with high deer density” and “endangered species in national and local government scale” . The species in Group A is “decreased and endangered” Group B is “decreased but not endangered”, Group C is “not decreased but endangered” and Group D is “neither decreased nor endangered”. We compared the relationship between proportion of each species groups and relative deer density indices. Proportion of Group B had rapidly decreased with relative deer density index increase, while proportion Group D had increased. Proportion of Group C showed unimodal response to relative deer density index. Proportion of Group A and B was high in the grassland and montane broadleaf forests with tall herb understory. Conservation emergency of these community types seem to be highest in the Chichibu-Tama-Kai National Park.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

This paper analyzes the transpiration and vapor conductance of a whole tree of Zelkova serrate in summer using its weight measurement results, taking into account the effects of the water stress of the tree. Measurement data of transpiration for water supply condition and no water supply condition are used for the analysis, and the effects of the water stress on the transpiration and vapor conductance are analyzed. The vapor conductance increased and was saturated as PPFD increased under the water supply condition. The photic saturation point was from 700 to 800 [μmol／(m²s)]. The peak of vapor conductance appeared in morning and that of transpiration appeared in afternoon under clear sky conditions. The transpiration rate increased by 1.7 times as saturation deficit increased by three times under the photic saturation condition. The peak value of transpiration and vapor conductance decreased as the soil water content decreased. The relashionship between vapor conductance and soil water content was hysteretic when the soil water content was varied by the water-supply stop test. Decrease in vapor conductance appeared two days after the water-supply stop, and recovery in vapor conductance appeared three days after the water-supply resumption.

View full abstract

We studied the effects of cold stratification, light, temperature, pericarp, storage, and burial depth on germination of Glehnia littoralis seeds, and temperature requirements for embryo growth. Radicles emerged from fewer than 2% of fresh seeds regardless of light condition or temperature. After cold stratification, radicles emerged from about 50% of seeds at 10-20℃, more so in the light than in the dark. Seeds stored dry at 5℃ for 12 months retained their germination ability. The pericarp had no effect on radicle emergence. Shoots emerged from about 60% of seeds sown at a depth of 2 or 5 cm. At a depth of 15 cm, shoots emerged from 16% of seeds, 40% of seeds rotted, and 70% of the remaining non-germinated seeds retained the ability to germinate. Embryo length at seed dispersal was 13% of that just before radicle emergence. Embryos grew in spring after snow melt, when temperatures were still relatively cool, then radicles and shoots emerged. These results indicate that seeds of G. littoralis have intermediate complex morphophysiological dormancy. When seeds are sown or seedlings are raised with the aim of restoring populations, the pericarp does not need to be removed, but seeds need cold stratification and should be buried at about 5 cm for optimum germination.

View full abstract

Until now, many researches have been accumulated knowledge about influences of plants on human mind and body. Focusing on the indoor plants as a natural factor in our everyday lives, we reviewed previous studies. The effects of plants on human mind and body have been investigated in various situations such as offices, medical setting, and educational setting. These studies show that indoor plants can raise the state of mind and body of people by reducing stress and fatigue, leading to a relaxed state. Now not only the plantscaping such as existence, amount and layout of plants, but also relationships between people and plants have come to be the topic in researching the benefits of plants. Further researches are required to clarify whether people's attitudes towards plants has influence on the benefits of plants.

View full abstract

[in Japanese]

View full abstract