We observed the change in understory vegetation over a period of four years after thinning within an old coniferous planted forest in the southern Boso peninsula where sika deer inhabit. Based on our observations, we examined the possibility of introducing broadleaved tree species through thinning. Number of tree species, tree cover rate, species richness and number of individuals with ≥ 1.3 m height tended to be higher in fenced plots than in non-fenced plots. In plots with severe disturbance during logging, numbers of tree species in the first and second year were larger, however, the increase of tree cover rate was slow, causing smaller tree cover rate in the fourth year than in less-disturbed plots. In terms of abundance, only Maesa japonica, a low tree species, and a few other species were dominant. Pionees species Idesia polycarpa and Broussonetia monoica grew well in fenced plots, which may tentatively achieve introduction of broadleaved tree species. Among high tree species, Neolitsea sericea, not a canopy tree species of climax forest, was abundant and grew well in both fenced and non-fenced plots, which may achieve multistory forest without fences. However, it was suggested to have large difficulties to prompt introduction of evergreen top-layer tree species, including frugivore seed dispersal species whose seeds may reach relatively easily, into old coniferous planted forest in warm-temperate zone through thinning.

Sprouting plays an important role in the succession of woody plants in fire-managed grasslands. In this study, we investigated the sprouting traits of Japanese aspen (Populus tremula var. sieboldii) in an annually burned grassland at the foot of Mt. Sanbe in Shimane Prefecture, Japan. We established a 2 m×2 m study plot and surveyed the distribution of roots, root sprouts, and sprouts from burned stems and rootstocks within the plot. The longest root per individual was＞10 m long and included 12 rootstocks. The horizontal roots were mainly found at a depth of ca. 1 cm below the soil surface, and current root sprouts were generated from ca. 3 mm diameter roots. Rootstocks with many large stems arising from sprouts generated in the previous year produced many current-year sprouts. Dead rootstocks tended to have thicker roots than living rootstocks. Highly productive rootstocks appeared to have survived annual burning of the aboveground plant parts. The results indicate that in this grassland, P. tremula var. sieboldii persists despite annual burning via regrowth through sprouting, and expands its distribution through new root sprouts generated from thin, elongating horizontal roots.

Among diverse methods for estimating economic values of natural environments, CVM (Contingent Valuation Method) is used in various research projects, including valuations of urban parks. Traditionally, photographs are used in valuations via CVM for explaining valuation targets to participants, followed by questions about WTP (Willingness-to-Pay) values. The number of studies using VR (virtual reality) is increasing, while previous research has not evaluated effects of explanation methods (VR vs. photographs) on WTP values through control experiments. In this study, we evaluated effects of explanation methods (VR vs. photographs) on WTP values of an urban park, while collecting customer loyalty scores (revisit intentions, word-of-mouth intentions), mood measurements (BMC-J), semantic differential method scores, and eye-tracking data. We also evaluated effects of view angles (front views vs. all-round views) on the WTP values and eye-tracking data. We found no difference between explanation methods in WTP values, customer loyalty scores, mood measurements, or eye-tracking data. However, WTP values after showing all-round views were higher than WTP values after showing front views. These findings suggest that, in valuations of urban parks using CVM, there is little advantage of using VR, which is more expensive and harder to use than photographs. Also, it can be important to control view angles. Further research is needed to evaluate effects of VR technology and view angles on WTP values, using CVM for a broad range of urban landscape design and participants with diverse demographic backgrounds.

To clarify the change in soil carbon stocks due to changes in land use from forest land and cropland to settlements, we considered the research method targeting new towns and industrial complexes where building land and roads are integrated, as typical settlements. Soil surveys were then conducted at more than 30 points nationwide. With reference to these results and the location information of the points converted from forest land and cropland to settlements, etc., the initial values of soil carbon stocks in settlements were calculated to be 21.9±16.5 MgC／ha when converted from forest land, and 22.8±17.6 MgC／ha when converted from cropland. The various land use forms of the settlements were summarized into four land use categories based on the current statistical classifications: building land, roads, grassland, and parks. Based on past data and aerial photographs, the soil carbon stock changes in each land use category due to vegetation recovery after conversion was added to the initial values, and the average soil carbon stock in settlements overall was calculated as 28.1±17.5 MgC／ha. With this method, it is possible to respond to changes in the area ratio of forest land and cropland to be converted to settlements and the composition ratio of land use categories in settlements to be converted. Therefore, it is possible to regularly update the average soil carbon stocks in settlements.

As feeding damage and trampling of green slopes by Japanese sika deer have increased and become widespread, the introduction of deer unpalatable plants into revegetation has attracted attention. The authors are studying methods of propagation and cultivation for greening with downy ground fern (Hypolepis punctata), a plant species not preferred by deer. This study investigated the possibility that multiple strains exist in downy ground fern. Rhizomes of downy ground fern collected from three different mountain forests were used to investigate whether there were special characteristic differences in terms of pot seedling propagation and post-planting growth. Tests were performed on the number of buds available for making pot seedlings, the germination rate of buds, seedling height, and above- and below-ground growth after pot seedlings were planted, with only the number of buds showing statistically significant differences among these characteristics. This suggested that a lineage may exist in downy ground fern.