ABSTRACT In order to clarify the effects of litter-layer removal treatment in 2013 on the ecosystem cycling of radiocesium in a Quercus-Pinus forest, soil 137Cs inventory and 137Cs concentration in litterfall were measured from 2014 until 2023. Due to the litter-layer removal treatment, the soil 137Cs inventory decreased to 67% of the control plot in 2014. During the measurement period, the 137Cs migration from the organic (O) horizon to the mineral soil horizon progressed. The effects of litter-layer removal on the 137Cs activity in litterfall varied depending on the litterfall type. Both the initial 137Cs concentration and the reduction coefficient (λ) derived from an exponential decrease in non-foliage litterfall 137Cs concentration were similar between the control and the litter-layer removal plots. For broadleaf litterfall, the initial 137Cs concentration after the litter-layer removal was lower than that in the control, while the λ remained similar between the litter-layer removal and control plots. In needleleaf litterfall, the initial 137Cs concentration in the litter-layer removal plot was lower than the control, but the λ was numerically higher in the litter-layer removal plot than in the control. Litter-layer removal treatment two years after the radionuclide fallout reduced the 137Cs concentrations in leaf litterfall from the year after treatment but did not significantly affect the subsequent reduction rate.

ABSTRACT The interaction between forests and water is crucial for meeting people’s water needs and for other ecological and hydrologic services. However, the existence of boreal forests, where the snow cover period lasts very long, can decrease or increase water yield depending on local climatic conditions. We use the results of our extensive research in Siberia and the available literature to identify the causes of this dual hydrological impact on forests. Our review shows that one major cause is that the specificity of snow water balance in the forest in contrast to open sites, in different climatic conditions, is insufficiently considered, and the climatic conditions are the major controls of forest hydrologic responses. We highlight this climatic role in nine central Siberian rivers whose catchment areas are in three vegetation zones (forest-tundra, northern taiga, and central taiga). We find that where winter is mild, forest is a more powerful snow water evaporator than open sites, whereas under severe winters it becomes a snow water accumulator and hence contributes to water yield. We conclude that a detailed comparative analysis of snow water balance between forest and non-forest ecosystems under different climates improves our understanding of the causes of the opposing conclusions as to the hydrologic impact of forests.

ABSTRACT Reforestation areas undergo rapid and continuous changes in vegetation structure, posing challenges for accurate and cost-effective monitoring. Here, we evaluate the accuracy of the geometric registration of orthomosaic images and digital elevation models using co-alignment, which does not rely on Ground Control Points or the Global Navigation Satellite System, to facilitate time-series analysis of the reforestation area. Three alignment methods – individual alignment (Ind), co-alignment among all epochs together (CA_All), and co-alignment between two epochs (CA_1on1) – were compared. The results show that both co-alignment methods significantly reduce horizontal and vertical relative errors compared to individually aligned images. This approach achieves geometric registration with horizontal accuracy within 0.05 m, whereas the vertical accuracy reaches approximately 0.1 m. When flight conditions and intervals differ markedly, the number of inter-epoch tie points decreases, occasionally leading to meter-scale misalignments. However, connecting more than two epochs reduces these errors and maintains accuracy sufficient for continuous monitoring. These findings suggest that co-alignment, combined with only one accurately georeferenced reference epoch, is highly effective for frequent and detailed forest monitoring. By leveraging a minimal subset of stable features (e.g. logging residues), multi-epoch unmanned aerial vehicle imagery can be seamlessly integrated, providing substantial cost and labor savings over traditional ground-control approaches. This paper presents an easy method for applying time-series analysis to early-stage forest management, with the potential to enable fine-scale detection of growth and changes in spatially complex and rapidly transforming landscapes in the future.

ABSTRACT Heat treatment is a promising measure to enable pest-free wood exports consistent with reducing environmental impact as an alternative to methyl bromide. In this study, we determined the heat tolerance of larvae and adults of the Japanese longhorn beetle Callidiellum rufipenne, a pest of Japanese cedar, Cryptomeria japonica, which is the main silvicultural wood exported from Japan. Larvae and adults were heated at 48°C, 50°C, and 54°C for 15 and 30 minutes. All the larvae were killed by heating at 50°C for 30 minutes, and 54°C for 15 minutes. Adults were 100% killed at 54°C for 15 minutes. Determination of the lethal temperature and exposure time of individuals serves as a reliable and minimal heat treatment schedule.

ABSTRACT Microbial and plant residues are the primary sources of soil organic carbon (SOC) in forest ecosystems. However, the relative contributions of microbial and plant residues to SOC in Moso bamboo (Phyllostachys edulis) forests remain poorly understood, despite Moso bamboo’s unique growth pattern distinct from that of tree species. In this study, we analyzed amino sugars and lignin phenols as biomarkers for microbial and plant residues, respectively, in the topsoil (0–10 cm) and subsoil (20–40 cm) of a Moso bamboo forest and investigated their regulatory factors. The results showed that microbial-derived amino sugars contributed 1.6% and 1.0% to SOC in the topsoil and subsoil, respectively, comparable to the contributions of plant-derived lignin phenols (1.6% and 0.8%). Both amino sugars and lignin phenols exhibited higher contributions to SOC in the topsoil than in the subsoil. Fine root biomass and microbial phosphorus (P) limitation regulated the contribution of amino sugars to SOC, while fine root biomass and the ratio of gram-positive to gram-negative bacteria controlled the contribution of lignin phenols. These findings highlight that microbial and plant residues contribute equally to SOC sequestration in Moso bamboo forests, with soil carbon and P availability playing critical roles in regulating their contributions. These findings may contribute to SOC management in Moso bamboo forests.

ABSTRACT The contribution of root systems, defined as the arrangement of belowground structures formed within plant communities through both individual plant root systems and their interactions, to the stability of forested hillslopes can be assessed at individual root and plant levels. Root systems influence both vertical and lateral flow by creating preferential flow pathways or bypassing flow and influencing pore-water development and slope stability. Root systems development differs depending on stand density (i.e. tree spacing) and species composition, which are also associated with resource competition among individual plants. Forest stand conditions related to plant density and resultant root system development possibly alter frequency and size of landslides. Scaling effect, defined as translation of insights of individual root system into entire hillslopes or watersheds, poses challenges due to the heterogeneity of forest stand conditions, soil properties, topography, and hydrological processes. The primary goal of this review is to explore how forest root systems and forest stand conditions influence landslide dynamics through hydrological and mechanical processes, thereby providing insights for further research to address sustainable forest management and disaster risk reduction.

ABSTRACT The acquisition, expansion, and dissemination of forest certifications are important topics, but continuity is equally essential. In this study, we aimed to clarify the challenges associated with obtaining and maintaining forest certification. We surveyed timber producers (forestry sector) and consumers (processing, construction, and paper industries) using a questionnaire, with a particular focus on the impact of the Tokyo Olympics and Paralympics. Our findings revealed that the demand expansion expected from the Tokyo Olympics and Paralympics did not materialize across all business categories, and 20–30% of companies were considering not renewing their certifications due to the conclusion of the events. However, we identified that the primary driving force behind obtaining and maintaining forest certification is market demand. This indicates that the certified timber supply chain effectively compels companies to acquire and sustain forest certification. The survey revealed a major challenge: the needs of distribution and processing companies were either not being communicated to timber producers or were deemed unnecessary. Without acquiring and renewing forest certification, timber producers would have to rely on imported certified timber. This study concludes that aligning timber producers with the needs of distribution, processing, and paper-related companies could increase the domestic timber supply and, ultimately, the availability of domestically certified timber.

ABSTRACT Sediment control dams are installed in some mountain regions to prevent streambed erosion and excessive sediment runoff, yet their effects on stream function are not well understood. In this study, we examined the effects of a sediment control dam on organic matter decomposition in a mountain stream by comparing upstream and downstream reaches in benthic and hyporheic zones over 5 seasons using the cotton-strip assay. Total decomposition rates, incorporating both macroinvertebrate-mediated and microbial-mediated decomposition, were lower downstream in the benthic zone in the fall and in the hyporheic zone in the summer and fall. Thus, sediment control dams appeared to alter organic matter decomposition rates downstream in some seasons. Environmental factors measured, such as temperature, NO3-N concentrations, and contribution of macroinvertebrates, influenced decomposition rates, but no single factor was sufficient to explain the effects of the dam and its seasonality in this study. Sediment control dams are smaller in size compared to water storage dams but widely distributed in mountain regions of Japan, and their cumulative effects on stream ecosystem function should be evaluated further for the management of mountain streams.

ABSTRACT The ecological compensation (EC) has been well recognized as one of the important policy measures for promoting sustainable development of the national forest parks (NFPs). But, how to acquire an adequate eco-compensation fund remains the key for its success. Previous researches were primarily focused on funding sources from either governments or NFP visitors. Few researches paid attention to the source of eco-compensation fund potentially contributed by NFP-related tourism businesses. To fill in the gap, this study analyzes tourism entrepreneurs’ willingness to pay (WTP) for NFP eco-compensation policy and the factors to influence tourism entrepreneurs’ WTP for NFP eco-compensation fund. In the process, we collected tourism firm data from Liaoning province in the northeast China. Both multiple-bounded dichotomous choice (MBDC) and regression models were used in estimating tourism entrepreneur’s WTP for NFP eco-compensation fund. Results show that six factors enable to impose a significant effect on tourism entrepreneurs’ WTP for NFP eco-compensation funds, including firm’s founding history, number of tourists accommodated, owner’s cognition on the environment system, anticipated outcome from implementing eco-compensation policy, attitude toward eco-compensation policy, and social benefit concerns. On average, a tourism business owner is willing to pay 1.61% of his or her firm’s annual profit for NFP eco-compensation fund. Individual firm in sectors of Travel agency, Hotel, Catering, and Retail is willing to pay NFP eco-compensation fund at ¥476 ($66), ¥4,178 ($580), ¥21,812 ($3,029), and ¥150,936 ($20,963) per year, respectively. The revealed information is applied to address NFP eco-compensation policy in China and around the world.

ABSTRACT The tsunami in March 2011 heavily damaged the Pinus thunbergii Parlatore erosion-control coastal forests of northeastern Japan. The restoration is in process but has been challenged by waterlogging resulting from soil compaction of artificial growth bases. In this study, a pot experiment was conducted to elucidate the waterlogging responses of two-year-old P. thunbergii seedlings in terms of waterlogging duration. Three waterlogging durations were set (7 days, 17 days, and 32 days, water table at soil surface) during August, followed by a waterlogging-free recovery period (28 days) in September. In this experiment, the responses of both above- and belowground organs during waterlogging and after the release from waterlogging were elucidated, focusing on parameters, such as transpiration and photosynthesis rates, as well as fine root growth and morphology. As a result, we found that under the conditions of our experiment, if the waterlogging duration is within 17 days, P. thunbergii seedlings can recover physiological activity in about a week; however, if the waterlogging duration is over 32 days, recovery after the release from waterlogging largely varied among seedlings. For the seedlings that could recover, recovery took at least 2 weeks, which required new fine root growth. In cases where the damage was irreversible, seedlings showed an overall decline. These results suggest that it is important to manage the waterlogging conditions so that P. thunbergii seedlings can recover without prolonged negative effects.