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The contribution of sapling banks to the coexistence of species with different shade tolerance under the "wave regeneration" regime has not been researched extensively. This study first assessed spatial and temporal variations in the relative dominance of two Abies species, Abies veitchii and Abies mariesii, with different shade tolerance in a wave‐regenerated forest. Second, we present the age structure and its spatial variation in young Abies stands (sapling stage) to exhibit the prevalence and variability of regeneration from sapling banks (defined as trees established 10 years before canopy opening). The relative dominance of A. mariesii, the more shade‐tolerant species, compared to that of A. veitchii, did not change over a period of 10 years, irrespective of stand developmental stages, indicating the importance of initial dominance in determining the local species composition. The tree ages at the sapling stage were significantly higher for A. mariesii than for A. veitchii. Approximately, 30% of all trees were likely to arise from a sapling bank, and 86% of them were A. mariesii. Age structure significantly varied between 5 × 5 m quadrats; some quadrats were dominated by A. mariesii originating from sapling banks, while others were dominated by A. veitchii that were established at the time of canopy opening. These results indicate that regeneration from sapling banks contributes to the dominance of A. mariesii and that the spatial variation in the abundance of trees originating from sapling banks is essential for the coexistence of A. mariesii with A. veitchii. [ABSTRACT FROM AUTHOR]

This study quantified the numbers and sex ratio of adult Sericania hidana (Coleoptera: Scarabaeidae) in a subalpine forest in 2017. Data from an area littered with coarse woody debris (CWD) created by a typhoon in 1959 were compared with those from an area where CWD had been cleared by salvage logging. Three types of traps were used: flight interception traps (FITs) with a black light, pitfall traps (PITs), and soil emergence traps (SETs). Carbon and nitrogen stable isotopes were analyzed to evaluate S. hidana diets and habitats. Overall, there were more S. hidana in the unsalvaged sites than in the salvaged sites. The FITs captured only males but SETs captured both males and females. The SETs on CWD captured more S. hidana than did SETs on soil in both the salvaged and unsalvaged sites. The PITs captured only a few individuals; thus, PITs are not suitable for studying this insect, although such traps were previously reported to capture S. hidana adults. Stable isotope analyses suggested that S. hidana feeds on a variety of plant materials, including living plants and CWD. These results suggest that CWD has long-term effects on insect populations. Soil emergence traps provide an effective method to quantitatively evaluate insect ecology, and FITs can effectively screen for the existence of insects. [ABSTRACT FROM AUTHOR]

Questions How do strong windstorms affect the dynamics of a wave-regenerated forest, long thought to be a shifting-mosaic steady-state system? Can large-scale disturbance lead to non-equilibrium dynamics in such a forest? Location A wave-regenerated Abies forest in northern Yatsugatake, Japan. Methods We analysed the motion of a 'regeneration wave' using aerial photographs (1947-2012) and field surveys (1954-2012). Long-term stand dynamics were surveyed along a transect established in 1954. Results The motion and structure of the regeneration waves indicated that the canopy was heavily disturbed by the typhoon in 1959. In 1954 (i.e. before the typhoon), the forest comprised stands of varying age based on a census along the transect. Older stands with high above-ground biomass and high canopies disappeared after the typhoon. Consequently, the post-typhoon forest mainly consisted of stands established around 1959. Thus, the typhoon caused a gradual change in age class distributions and in the above-ground biomass of the forest. Species composition also varied considerably across census years, clearly indicating the influence of large-scale disturbance. Conclusions The study forest changed drastically in structure after a major typhoon, and it continued to change during the subsequent 50 yr. The large-scale disturbance clearly affected species composition, potentially contributing to the co-existence of two Abies species. Our results suggest that, in combination, frequent small-scale disturbance and infrequent large-scale disturbance produce a non-equilibrium state with respect to forest structure and species composition. [ABSTRACT FROM AUTHOR]

Climate changes are assumed to shift the ranges of tree species and forest biomes. Such range shifts result from changes in abundances of tree species or functional types. Owing to global warming, the abundance of a tree species or functional type is expected to increase near the colder edge of its range and decrease near the warmer edge. This study examined directional changes in abundance and demographic parameters of forest trees along a temperature gradient, as well as a successional gradient, in Japan. Changes in the relative abundance of each of four functional types (evergreen broad-leaved, deciduous broad-leaved, evergreen temperate conifer, and evergreen boreal conifer) and the demography of each species (recruitment rate, mortality, and population growth rate) were analyzed in 39 permanent forest plots across the Japanese archipelago. Directional changes in the relative abundance of functional types were detected along the temperature gradient. Relative abundance of evergreen broad-leaved trees increased near their colder range boundaries, especially in secondary forests, coinciding with the decrease in deciduous broadleaved trees. Similarly, relative abundance of deciduous broad-leaved trees increased near their colder range boundaries, coinciding with the decrease in boreal conifers. These functional-type-level changes were mainly due to higher recruitment rates and partly to the lower mortality of individual species at colder sites. This is the first report to show that tree species abundances in temperate forests are changing directionally along a temperature gradient, which might be due to current or past climate changes as well as recovery from past disturbances. [ABSTRACT FROM AUTHOR]

We explored structural mean and variation along a chronosequence in a wave-regenerated forest on Mt. Shimagare, Japan, and examined differences in the components of variation between developmental stages. Because there are several strips of stands at the same developmental stage in the forest, between- and within-strip variances (i.e., variance components) were analyzed at each stage. Three strips were selected for each of three developmental stages (one for saplings to three for mature trees), and four plots were established in each of the strips. Stem densities and stand basal areas for trees taller than 20 cm were computed for all plots. Six Bayesian ANOVA models were compared to examine the temporal patterns of stage means, total variance, and the variance components for the two stand structural parameters. The results of the model comparison suggested that the variation in stem densities decreased from the sapling stage to the mature stage, but variation in stand basal areas remained roughly constant throughout forest development. For both density and basal area, the relative magnitudes of each variance component compared to the total variance differed between stages; the ratios of between-strip variation to within-strip variation were highest at the mature stage. Our results suggest that forest structure exhibited higher variability during development of the wave-regenerated forest than was assumed in previous studies and that the variance components for the forest structure varied temporally among developmental stages. This study thus illustrated a potential application of the chronosequence approach to infer the dynamics of a spatially heterogeneous and hierarchically structured ecosystem. [ABSTRACT FROM AUTHOR]

Litter and soil organic matter decomposition represents one of the major drivers of carbon and nutrient cycling in a given ecosystem; however, it also contributes to a significant production of relevant greenhouse gasses. The Japanese archipelago spans several biomes (boreal‐temperate‐subtropical) and covers a large range of elevations and ecosystem types. Hence, the comprehension of this fundamental biogeochemical process in diverse ecosystems is crucial to maintain their ecosystem services. In this article, we have provided data on plant leaf decomposition from 33 research sites across Japan. At each site, standard litter material with different decomposition rates, rooibos tea and green tea were incubated for 90 days between 2012 and 2016 and the remaining mass was recorded. In total, 1904 bags were used. In addition, supplementary measurements of environmental variables essential for the interpretation of the collected data, such as soil and vegetation, were recorded. Plot‐level averages of the remaining mass rates of bag contents after incubation ranged 0.17–0.51 for green tea and 0.54–0.82 for rooibos tea. Continued monitoring will also provide important insights into the temporal dynamics of litter decomposition. [ABSTRACT FROM AUTHOR]