Increased municipal workloads and personnel shortages have been flagged as problems in the operation of the Forest Management System (FMS) that was started in 2019. Although wide-area collaboration is expected to be an effective countermeasure, there are no studies on the structure of such collaboration and the impact of its introduction on each entity. This study aimed to clarify the role of wide-area collaboration within the FMS and the structure of collaboration among various entities, targeting the Chichibu region of Saitama Prefecture where a specialized organization was established to administer the FMS and where various entities are fundamentally collaborating with municipalities. Interviews with officials of the Saitama Forestry Agency from one city and four towns, staff of forest owner's cooperatives, forestry enterprises, and forest owners were conducted. The main results show that Chichibu City and intensification promoters play a central role in the operation of the FMS, while the four towns formulated their own plans, Saitama Prefecture provided advice and support, and forestry enterprises implemented forest operations. Furthermore, the four towns were able to reduce their workloads, reduce overall costs, improve the efficiency of information access, accumulate know-how, make progress in operations, and secure land for small forestry enterprises. However, ongoing challenges include an increased workload for Chichibu City and assignor organizations. Based on the above, it can be inferred that the introduction of wide-area collaboration into this system will contribute to a reduction in municipal workloads.

To clarify the long-term trend of nitrogen (N) deposition, the existing monitoring data was analyzed at the regional and national level from 1976 to 2018. We used the data of annual N depositions from the National Institute for Environmental Studies, the Ministry of the Environment, the Forestry and Forest Products Research Institute, and the Japan Meteorological Agency. Annual median of national N wet deposition was 6.0 kg N ha^-1 in 1988 (n＝24) and increased to 7.6 kg N ha^-1 in 2000 (n＝92), then it was 7.6 kg N ha^-1 in 2010 (n＝82). In 2018 N wet deposition decreased to 6.2 kg N ha^-1 (n＝76). The state space model demonstrated that N wet deposition significantly increased, after which tended to decrease at Eastern Japan from 2004, at the Japan Sea area, and in the nation from 2012. Nitrogen dry deposition averaged 6.0±0.1 kgN ha^-1 year^-1 (n＝109), total N deposition; the sum of wet and dry deposition, was 11.5±1.6 kgN ha^-1 year^-1, N dry deposition ratio ranged from 0.41 to 0.61 during 2003-2018 based on the results of seven stations. Cumulative N deposition was estimated to have exceeded 300 kgN ha^-1 over the past 30 years.

Due to radioactive contamination following the Fukushima Daiichi Nuclear Power Plant accident in 2011, shipping restrictions have been imposed on wild mushrooms in a wide area of eastern Japan. In order to contribute to more efficient restriction and its lifting, I focused on the variation of radiocesium (¹³⁷Cs) concentration for each species obtained within the same municipality, and 7,920 sample data collected in prefectures in eastern Japan from 2014 to 2019 were analyzed. The ¹³⁷Cs concentrations of mushroom species collected in municipalities could be regarded as a lognormal distribution. The geometric standard deviation (GSD) for each species and municipality, which is an indicator of the variability of the lognormal distribution, tended to converge as the number of samples increased, while the values were considered to vary to 2-3 by species. The ratio of the geometric mean (GM) of ¹³⁷Cs concentrations for each species was constant regardless of the sampling municipality, suggesting that the trend in species concentrations is common regardless of the region. The concentration distribution considering the variation of species showed that there were cases where the concentration distributions overlapped even when the geometric mean concentrations differed by a factor of 10. On the other hand, there were cases in which the concentration distributions were very similar even though the species differed (e.g., nameko and mukitake, or bunaharitake and hiratake). Such information is important when considering shipping restriction or its lifting.

This study examined the effects of damage caused by sika deer on forest dynamics and recruitment of dominant species and evaluated forest survivability based on a 20-year tree measurement (2000-2020) in a fixed 1-ha plot in an old-growth sub-alpine coniferous forest. Cumulative damage percentages steeply increased until 2011 for all stratums: canopy trees (DBH ≥ 5 cm and reaching close to the canopy layer), understory trees (DBH ≥ 5 cm and not reaching the canopy layer), and saplings (DBH＜5 cm and height ≥ 1.3 m). Bark stripping was observed in 69-88％ damaged stems in each stratum. Mortality rates were higher in the years 2011-2016 compared with the other periods for canopy and understory trees and remained nearly constant for saplings. Mortality rates varied according to tree species, and the tree species composition changed considerably between 2000 and 2020. The total basal area of canopy and understory trees increased slightly owing to the radial growth of stems that remained alive for 20 years. Recruitment rates to each stratum decreased to＜0.1％ during the observation period. Based on mortality and recruitment rates since 2011, the number of canopy trees was estimated to halve after 68-90 years. This indicates that if the damage level is not improved, forest decline in the near future is imminent.