The vegetation in the Misen Mountains on the Shimane Peninsula has been strongly affected by sika deer, Cervus nippon. Therefore, we investigated the scars caused by browsing and debarking on every tree and the number of each species in the study forest and discuss the effects of sika deer on the survival of tree species. We examined five forest types: red pine (Pinusdensiflora), hornbeam (Carpinustschonoskii), oak (Quercusserrata), broad-leaved evergreen (Castanopsissieboldii), and a forest of trees killed by pine wilt. Neolitsea sericea was the most abundant tree in our study forests. There were large numbers of Q.serrata,P.densiflora,C.tschonoskii,Ilexpedunculosa, and Euryajaponica var. japonica, which showed lower rates of browsing and debarking. TWINSPAN indicated that the species composition of adult trees (diameter at breast height DBH＞4 cm) could be separated into the five forest types according to the dominant species. By contrast, the species composition of young trees (DBH＜4 cm and height＞2 m) and saplings (height＜2 m) did not separate according to the dominant species. Although every forest type contained many N.sericea saplings and young trees, the greatest number of young trees was in the dead pine forest, while the greatest numbers of saplings were in the pine forest and dead pine forest. In our study forests, N.sericea germination was stimulated by two factors: long-term feeding of sika deer and death of canopy trees in the pine forest.
Buried seeds in forest soils have attracted attention as a natural greening material, making predictions of their number and spatial distribution important. We aim to assess the degree of variation in forest seed bank characteristics based on a nested sampling approach. The study was conducted in a secondary forest that consists of four patch types (conifer, canopy gap, deciduous broadleaf tree, and evergreen broadleaf tree) in a 100-m slope. Three 5×5m plots containing three 20×20cm quadrats were established under each patch type. We obtained soil samples from a depth of 0―5cm, and seedling emergence was monitored over 5 months. In total, 116 seeds germinated (6.4/L), and twenty-five species were identified, with a dominance of the shrub Eurya japonica and the conifer Chamaecyparis obtusa. Variations in seed bank density were small between patches but were large between plots within the same patch type, and the latter accounted for approximately half of the total variances. The seed bank density tended to decrease in high-light environments (Indirect Site Factor＝0.12―0.16) and increase in plots with high densities of acorn-producing overstory trees, although there were also substantial within-plot variations in seed bank density, and further studies are necessary to confirm the results. Our simple method of nested sampling and statistical analysis for evaluating spatial heterogeneity of forest seed bank and for analyzing correlations with vegetation and micro-environmental factors are useful for considering effective sampling strategies of forest topsoil for revegetation practices.
The slope revegetation guidelines for national parks framed by the Japanese Ministry of the Environment require the incorporation of information on ecological succession when designing revegetation strategies. Therefore, it is important to elucidate revegetation process following disturbances caused by landslides. In the present study, we investigated the vegetation it was established after the landslide in semi-natural grasslands in Aso, Kumamoto, Japan. We selected three sites of different stage of succession in Machikoga Pasture―a new landslide site (NLS) and an old landslide site (OLS) wherein the most recent landslides occurred four and 26 years ago, respectively, and a control site (C) with no recent landslide disturbances. Vegetation cover in OLS was higher than that in NLS. The dominant species changed with the sites. The OLS site was dominated by Arundinellahirta and Lespedezabicolor, whereas the C site was dominated by Miscanthussinensis. In addition, the floristic composition was different on sites. The occurrence of commonly occurring species in OLS, such as Patriniascabiosifolia, was high only in specific stages of succession. The cooccurrence of different age of landslide sites enhanced plant species diversity in the semi-natural grasslands in the study area. Consequently, the vegetation may recovers as time proceeds and the presence of vegetation of different landslide ages derived from landslides of different ages increases the species diversity of semi-natural grasslands in the Aso area.
White oasis soil, which is widely distributed in the Inner Mongolia Autonomous Region of China, prevents the growth of root systems by forming an impermeable layer of hard calcium carbonate, and therefore is not suitable for plant growth. Consequently, it is difficult to restore the ecology once the land is devastated. Efforts to restore or reproduce the ecology in this region by continuously planting and watering large seedlings have had little success. Therefore, this study examined how to introduce woody plants into white oasis soil under limited watering conditions. For this study, nursery block seedlings of eight tree species were planted to compare their compatibility with white oasis soil. As a result, regarding the compatibility with white oasis soil, the survival rate one year and two months after planting was highest at 98％ for Ulmus pumila L., 85％ for Syringa oblata Lindl., 52％ for Prunus persica (L.) Batsch, and 40％ or less for the other five tree species. The result of the above test suggests the possibility of introducing woody plants into white oasis soil under limited watering conditions by planting U. pumila, S. oblata, P. persica and other tree species highly compatible with white oasis soil.