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Assessing long-term changes in the biomass of old-growth forests with consideration of climate effects is essential for understanding forest ecosystem functions under a changing climate. Long-term biomass changes are the result of accumulated short-term changes, which can be affected by endogenous processes such as gap filling in small-scale canopy openings. Here, we used 26 years (1993–2019) of repeated tree census data in an old-growth, cool-temperate, mixed deciduous forest that contains three topographic units (riparian, denuded slope, and terrace) in northern Japan to document decadal changes in aboveground biomass (AGB) and their processes in relation to endogenous processes and climatic factors. AGB increased steadily over the 26 years in all topographic units, but different tree species contributed to the increase among the topographic units. AGB gain within each topographic unit exceeded AGB loss via tree mortality in most of the measurement periods despite substantial temporal variation in AGB loss. At the local scale, variations in AGB gain were partially explained by compensating growth of trees around canopy gaps. Climate affected the local-scale AGB gain: the gain was larger in the measurement periods with higher mean air temperature during the current summer but smaller in those with higher mean air temperature during the previous autumn, synchronously in all topographic units. The influences of decadal summer and autumn warming on AGB growth appeared to be counteracting, suggesting that the observed steady AGB increase in KRRF is not fully explained by the warming. Future studies should consider global and regional environmental factors such as elevated CO2 concentrations and nitrogen deposition, and include cool-temperate forests with a broader temperature range to improve our understanding on biomass accumulation in this type of forests under climate change. Supplementary Information The online version contains supplementary material available at 10.1007/s10265-021-01358-5.

Stored carbohydrates in trees do not act as key requirements for mass flowering in a masting species, Fagus crenata. Many tree species exhibit high interannual variability in flower production at population level, called mass flowering. These species may need to store a certain amount of carbohydrate resources in trees for flowering. Based on this assumption, we hypothesized that masting tree species would blossom heavily when carbohydrates were sufficiently stored up in some specific organs. To test this hypothesis, we studied the relationship between stored carbohydrates in various organs just before the season of flower bud initiation and the number of flowers in the following year in a typical masting species, Fagus crenata (Fagaceae), over 10 years. In addition, we estimated the carbon accumulation period required for flower production by radiocarbon (14C) contents of inflorescences in this species. During the study period, the individuals studied flowered synchronously about every 2 years, but levels of the flowering magnitude were different from each other. Total nonstructural carbohydrate (TNC) concentrations also exhibited large interannual variations, while the long-term trend of TNC over the 10-year observation period showed a general increase in all the investigated tree individuals. There was no significant relationship between the TNC concentrations in each organ and the number of flowers produced in the following year, including the massive flowering event in 2006 when all the selected trees flowered heavily. Fagus crenata produced inflorescences using carbon resources assimilated mainly in the year when the flower buds were formed. These results suggest that the storage of carbohydrate resources might not be a limiting factor in the occurrence or frequency of flowering in this species.

Trees reduce their allocation to apical growth compared with that to radial growth during later life stages. This has often been attributed to hydraulic and mechanical limitations; however, a growth–reproduction tradeoff might also play an important role. To test whether the height–diameter (H–D) relationship in trees changes with the timing of the onset of reproduction, we analyzed the H–D relationship of 13 deciduous broad-leaved tree species in a Japanese old-growth temperate forest using linear and segmented-linear regression models. These models showed a better fit than common continuous models (simple allometry and saturating curve). For 11 out of 13 species having break points on the H–D lines, we assessed whether the height at the breakpoint (BPH) was related to the height at the onset of reproduction determined by multiyear observatory records on several trees. Although BPH estimates for these 11 species were highly variable, most were within 3.1 m of the stable flowering height (staFLH), or the height at which trees achieve the ability to flower regardless of their growth conditions. The interspecies mean value of the difference between staFLH and BPH was only 45 cm, which suggested a causal relationship between these parameters. BPHs of nine out of 11 species were within the canopy layer and, for the two remaining species, were within the subcanopy layer. These results suggest that several species in this forest begin to reduce their allocation to apical growth around the canopy layer at the onset of stable reproduction.

In 1984 at Mt. Ontake in Japan, an earthquake caused a devastating landslide, and as a result, the vegetation on the south slope of the mountain was completely eliminated. In higher elevation (2000 m) areas, revegetation has not yet been completed even 30 years after the landslide. Revegetation progress throughout the area was heterogeneous. In the partially revegetated areas, actinorhizal plant species such as Alnus maximowiczii and Alnus matsumurae have been found. In the present study, we investigated the Frankia communities in the higher-elevation area using sequence analysis of the amplified nifH (dinitrogenase reductase) gene from nodule and soil samples collected in the disturbed region, undisturbed forest, and in the boundary between the disturbed region and the undisturbed forest. Phylogenetic analysis of partial nifH sequences revealed the presence of six clusters, each of which consisted of highly similar (> 99%) sequences. Four clusters showed significant sequence similarity to Frankia (three Alnus- and a Casuarina-infecting strains). Diversity in the Frankia community was relatively low—only one or two clusters were detected in a site. At most of the sampling sites, a dominant cluster in a nodule coincided with that in rhizosphere soil, indicating that community structure in the rhizosphere is a primary factor that determines occupancy in a nodule. No significant difference in community structure was observed between plant species. Diversity in the Frankia community varied depending on revegetation progress. Cluster A, which was the most dominant in the disturbed region, was likely to have invaded from undisturbed forest.

Summary Many woody plants resprout to restore above-ground biomass after disturbances or to survive in stressful environments. Resprouting requires carbohydrate storage, but the general relationship between resource allocation patterns and resprouting ability remains unclear because it can be influenced by the disturbance regime to which species have adapted. We studied deciduous broadleaved trees that coexist in a Japanese cool-temperate forest to investigate the relationships among the biomass and total non-structural carbohydrate (TNC) allocation patterns of saplings, resprouting ability and functional traits. The study species comprised 16 single-stemmed species that only resprout when above-ground biomass loss occurs and eight multi-stemmed species that resprout regardless of whether above-ground damage occurs or not. Single-stemmed species with better juvenile resprouting ability had larger roots, whereas multi-stemmed species with better juvenile resprouting ability did not necessarily depend on below-ground reserves. Species that retain their ability to resprout until a larger size had a higher root TNC content as saplings, suggesting that they can survive major disturbances such as fire and coppicing by resprouting supported by TNC stored in their roots. Species with shade-tolerant traits (i.e. low foliar nitrogen indicating low photosynthetic capacity, high wood density indicating high defensive investment) had small below-ground TNC reserves irrespective of resprouting types. On the other hand, multi-stemmed species with high wood density and high LMA (indicating high photosynthetic capacity) had small above-ground TNC reserves. Contrary to our hypothesis, a species’ maximum size did not relate to the size of its below-ground reserves. By considering the differences in resprouting types, we suggest more complex control of resprouting than was formerly proposed. Variation in the resprouting ability of single-stemmed species was based on a trade-off between below-ground reserves for resprouting and shade-tolerant traits. However, multi-stemmed species can vigorously resprout irrespective of the size of its below-ground reserves. Their multi-stemmed architecture, well-defended wood, high photosynthetic capacity or large above-ground carbohydrate reserves seem to respectively contribute to their persistence. Such variation in the resprouting strategy based on a trade-off between shade tolerance and resource storage would promote species coexistence under a range of disturbance regimes and light environments.

Summary Individual plants provide a habitat patch for foragers where the sought-after resources (e.g. leaves, fruits and seeds) are clustered in locally dense aggregations. Characteristics of these resources often vary greatly even within individual plants, which is known as within-plant or subindividual variation. To best describe properties of the patch (individual plants), the higher moments of trait-value distributions must be included in addition to the mean values. However, the question whether differences in within-plant variability of a given trait influence the foraging behaviours of consumers has been mostly untested. To test the hypothesis that differences in within-plant variation of traits can influence the patch selection behaviour of seed consumers, we used the mean, coefficient of variation (CV) and skewness of within-plant distributions of two Quercus serrata (Thunb) seed traits (weight and tannin content) as descriptors of plant phenotypes. We then examined the relationships between these descriptors and patch selection by the wood mouse Apodemus speciosus, where individual Quercus trees formed a foraging patch for seed removal. We collected 8594 seeds from 26 individual trees in a forest in northern Japan. We then measured their weight and tannin content, marked and returned them to the locations where they were found, and traced their fates in relation to seed removal by the wood mouse. Tannin content was nondestructively estimated using near-infrared spectroscopy (NIRS). There was notable within-plant variation in seed weight and tannin content. Generalized additive modelling revealed that trees with a large mean and CV of seed weight and those with a small CV and skewness of tannin content had a high frequency of seed removal. These results highlight the importance of considering the within-plant distribution of seed trait values, in addition to the mean trait values of individual seeds, when describing plant phenotypes. The inclusion of these data is essential to understand the ecological and evolutionary processes at work in plant–animal interactions.

Summary One of the major problems in understanding growth trends in long-lived trees is the difficulty of separately quantifying the effects of tree size and age. Careful statistical control of the axiomatic age×size covariation is therefore required to identify long-term trends in tree growth and their drivers, and to predict forests' responses to environmental changes reliably. To address this issue, we present a novel tree growth model: a ‘two-dimensional log-normal growth model’. This is an extension of the one-dimensional log-normal growth model, in which tree growth is modelled primarily as a function of size. Our model assesses the trend in tree growth over time by explicitly partitioning the effects of age and size, controlling the covariation. The model is then extended to incorporate the effects of neighbourhood crowding and individual tree variation. To demonstrate our model, we apply it to long-term monitoring data from a mature (104-year-old) plantation of Japanese cedar. Thinning operations of various intensities have been applied to this plantation, and the diameter of each individual tree has been measured repeatedly. We observed a pronounced age-related decline in diameter growth. However, at each age, greater tree size was associated with a higher growth rate. The growth–size curve predicted from the model became flatter with tree age, and the curve's peak shifted rightwards as tree age increased. The model reveals that the sensitivity of a target tree to neighbourhood crowding depends strongly on neighbours' size and also provides an estimate of among-tree variation in growth performance. Although the relationships between growth, size and age in long-lived trees are very complex, our growth model supports the conclusion that it is possible to predict long-term trends in tree growth reliably with respect to both age and size. In addition, the model's flexibility will facilitate more robust testing of species-specific responses to long-term environmental changes.

Pollination is a key process for reproduction and gene flow in flowering plants. Anthropogenic habitat fragmentation, however, can disrupt plant–pollinator interactions, and may have a negative impact on the reproductive success and population viability of entomophilous plants. Heterodichogamous plants containing protandrous and protogynous individuals within a population may be susceptible to habitat fragmentation due to a lack of available mating partners. In this study, we investigated the effects of forest fragmentation on the mating system in the heterodichogamous plant Acer mono, a major constituent of cool-temperate deciduous forests in Japan. Microsatellite analysis was applied to 212 adult trees and 17 seed families from continuous and fragmented forests. Dispersal kernel modeling using the neighborhood model indicated that pollen dispersal of A. mono was highly fat-tailed. The estimated parameters of the model suggested that the siring success of a pollen donor increased approximately fivefold, with a 100 cm increase in its diameter at breast height (DBH), and that disassortative mating was five times more frequent than assortative mating. The mating system parameters of each mother tree, outcrossing rate (tm), biparental inbreeding (tm−ts), and paternity correlation (rpm) varied among sites and conditions, depending on the local density of potential pollen donors. Whereas A. mono was effectively outcrossed (tm=0.901, tm−ts=0.052, and the number of effective sires was 1/rpm=14.93) in the continuous forest, clumped trees within the fragmented forest showed increased biparental inbreeding and reduced pollen pool genetic diversity (tm=0.959, tm−ts=0.245,1/rpm=1.742) as a result of localized mating combined with spatial genetic structures. In contrast, the isolated trees had a higher selfing rate, but the pollen pool diversity was maintained (tm=0.801, tm−ts=0.022, and 1/rpm=15.63) due to frequent long-distance pollination. These results suggest that although pollen limitation following habitat fragmentation could result in negative genetic consequences, enhanced long-distance pollination across a fragmented landscape could partly compensate for this limitation depending on the degree of forest fragmentation.

Summary Resprouting of woody species after above-ground damage may help plants to persist longer at a given site and quickly reoccupy disturbed sites, thereby strongly influencing forest dynamics. Resprouting has been discussed from two adaptation perspectives: recovery from damage by catastrophic disturbance and survival in frequently disturbed shaded understorey. However, few studies have comprehensively dealt with both adaptation types to understand resprouting strategies. To understand the adaptive significance of resprouting, we assessed the size dependence of resprouting ability after stem clipping for 24 deciduous broad-leaved species, including shrubs, sub-canopy and canopy trees, in a cool-temperate forest in Japan. The community assembly includes species adapted to past catastrophic disturbances (e.g. fire, logging) and to stable forest with intermittent treefall (currently the dominant disturbance). We correlated resprouting ability with life-history strategies based on demographic parameters and plant functional traits, such as leaf mass per area (LMA), leaf toughness and wood density. All the studied species could resprout in juveniles, and resprouting ability increased as stump size increased. Most sub-canopy and canopy trees lost their ability to resprout after attaining a particular stump size, whereas shrub species retained the ability to resprout throughout their lifetimes. The relative growth rate, LMA and foliar nitrogen did not greatly influence the resprouting ability of a species. In contrast, species with smaller maximum size, lower leaf toughness and lower wood density had better juvenile resprouting ability. This better resprouting ability may have evolved because these characteristics make them more vulnerable to shaded understorey. However, species with larger maximum size and lower leaf toughness retained their ability to resprout to a larger size. Synthesis. A better resprouting ability is related to the ability to survive frequent disturbances, in juveniles, which are characteristics of both forest understorey and frequent fire or drought. To retain resprouting ability until grown seems to be an adaptation to survive infrequent large disturbances. Light-demanding species, which generally have better resprouting ability than shade-tolerants both in juveniles and adults, are adapted to disturbances of various scale and frequency; however, shade-tolerants could survive well in the understorey due to a combination of stronger physical defences and resprouting ability.

Montane riparian forests exhibit a higher diversity of tree species than adjacent stands. This pattern is thought to be generated by the unique disturbance regime of riparian forests, including canopy gap formation and fluvial disturbance (e.g., transport of boulder/gravel sediments), which provides a variety of habitat conditions for regeneration (habitat niche segregation). Although segregation of micro-environmental conditions for seedling establishment has been confirmed, habitat segregation for saplings remains untested. Thus, to determine if the composition and structure of the riparian sapling community is influenced by canopy and fluvial disturbances, we sampled 11 canopy-gap sites and 3 fluvial boulder-deposit sites, as well as beneath-canopy sites that had not been disturbed recently, in a temperate mixed-species deciduous forest. We analyzed the distribution patterns of saplings for 31 canopy and subcanopy species. Saplings were found mainly on the disturbed sites compared with the be...

Intraspecific variation in seed production schedule and its effects on seed characteristics were examined in the deciduous oak species Quercus serrata in Iwate Prefecture, northern Japan. Seed production schedule differed markedly among 31 individual trees. The median dates of seed production differed by over 1 month between the earliest and latest individuals. Relationships between seed production schedule and seed characteristics were investigated at two different scales: the among-tree scale and the within-tree scale. At the within-tree scale, analyses revealed that the seeds dispersed by a tree later in the season tended to be larger in size and lower in tannin concentration. Similarly, at the among-tree scale, analysis revealed that trees with a later seed production schedule produced on average larger acorns. However, no clear tendency was observed between seed production schedule and mean tannin concentration. The observed variation in seed production schedule is likely to affect seed fate per se, and also via changes in seed characteristics.

How deterministic or stochastic is tree regeneration in a temperate forest? To answer this question, we analyzed the relative effects of abiotic and biotic factors on seed and seedling demography of tree species in an old-growth temperate forest, Ogawa Forest Reserve, Japan. The working hypothesis was that seed and seedling demography of trees would be controlled more deterministically in comparison with tropical forests and that the magnitude of deterministic effects of the abiotic and biotic factors would depend on regeneration traits relating to seed dispersal ability. We examined 5 abiotic factors (litter and humus cover, vegetation cover, light level, soil moisture, and relative elevation) and 2 species-specific biotic factors (distance from the nearest conspecific adult and density of conspecific seeds or seedlings) to quantify their contribution to the spatial variation in seedling emergence and survival for 18 principal tree species in the community. The results showed that conspecific s...

Heterodichogamy is a form of sex expression in which protandrous and protogynous individuals coexist, and is considered to be a mechanism that avoids selfing and promotes disassortative mating. We examined mating patterns in a heterodichogamous maple, Acer mono, using microsatellite markers. Parentage analysis revealed a selfing rate of only 9.8%. Disassortative mating between flowering types significantly exceeded within-type mating, but the mating patterns were better explained by flowering phenology (i.e., the temporal overlap between the female and male stages). Heterodichogamy in A. mono thus appears to promote outcrossing without requiring obligate self- or cross-incompatibility systems, although it did not guarantee disassortative mating. Multiple-regression analysis suggested that successful reproduction of pollen parents significantly increased with increased flower production and reciprocal flowering synchrony, but decreased only marginally with mating distance, although the distribution of mating distances suggested leptokurtic dispersal of pollen.

Gene fl ow is crucial to plant reproduction because it infl u-ences the reproductive success and fi tness of individuals and the genetic structure of the population. Genetic analysis has re-vealed that pollen grains tend to be transported over longer dis-tances than seeds ( Chase et al., 1996 ; Dick et al., 2003 ; Isagi et al., 2007 ). Many angiosperms rely on animals for pollination, with insects being the major animal vectors ( Goulson, 1999 ). Flowers are often visited by a variety of insect species, which vary widely in morphological and behavioral features ( Herrera, 1987 ; Mayfi eld et al., 2001 ; Adler and Irwin, 2006 ). Thus, pol-linators may have different effects on the reproductive success, fi tness, and population structures of the plants they pollinate. To understand plant mating systems, plant – insect interactions, and coevolution, it is essential to study the effects of fl ower-visiting insects on pollination. Pollination effi ciency, the contribution of fl ower visitors to plant pollination, has been evaluated in various ways. The basic approach used to estimate a given pollinator ’ s contribution to pollination involves observing fl ower visits and evaluating variables such as visitation frequency and visitation duration ( Primack and Silander, 1975 ; Galen and Newport, 1987 ; Herrera, 1989 ). To evaluate a pollinator ’ s ability to transfer pollen, re-searchers have examined the number of pollen grains trans-ported ( Primack and Silander, 1975 ; Mayfi eld et al., 2001 ; Ivey et al., 2003 ), the degree of pollen removal ( Conner et al., 1995 ), the amount of pollen deposited ( Herrera, 1987 ; Muchhala and Potts, 2007 ), and the distances and patterns of movement ( Olesen and Warncke, 1989 ; Wid e n and Wid e n, 1990 ; Schulke and Waser, 2001 ). Fluorescent dye has also been used as a pollen analog to estimate pollinator movement ( Murawski and Gilbert, 1986 ; Adler and Irwin, 2006 ). However, none of these measurement techniques provide information on the genetic composition or diversity of the pollen grains that are transported to fl owers. The genetic composition and diversity of transported pollen strongly infl uences fertilization success and offspring fi tness via self-incompatibility and inbreeding depression. For example, pollen grains that are transported to another part of the same plant of a self-incompatible species produce no seeds, and even in self-compatible species, self-pollination may yield seeds of lower fi tness ( Husband and Schemske, 1996 ; Keller and Waller, 2002 ). Therefore, to assess the contribution of pollinators to ef-fective pollination, it is necessary to determine quantitative and genetic qualitative characteristics of transported pollen grains. Several methods of distinguishing different pollen donors have been used. Color polymorphism of pollen grains ( Jorgensen et al., 2006 ) can be readily assessed, but the discrimination is relatively poor and adaptation is restricted to specifi c species. Although gene transformation ( Havens and Delph, 1996 ; Hudson et al., 2001 ) and differences in ploidy ( Williams et al., 1999 ) can also distinguish pollen genotypes in vivo, these meth-ods are unsuitable for processing the large numbers of samples required for analysis of natural populations. We previously developed a method for direct genotyping of single pollen grains (Matsuki et al., 2007) that allows pollen from different pollen donors to be distinguished with high reso-lution using multiple microsatellite markers. Genetic tagging of individual pollen grains is useful for the detailed analysis of plant mating systems and drawing correlations between plants and fl ower visitors. In this study, the pollen adhering to insects was analyzed using quantitative and qualitative criteria

The effects of local population density, sex morph [protogynous (PG) or protandrous (PA)], and individual tree size on the demographic processes of seed production were investigated in a heterodichogamous maple, Acer mono Maxim. var. Marmoratum (Nichols.) Hara f. dissectum, in a temperate forest of Japan. As the distance from conspecific reproductive adults increased, the percentage of immature seed fall and empty seeds increased significantly, indicating higher pollination success along with local population density. Although the difference was not distinct, pollination success was affected by the local population density of the reciprocal sex morph rather than that of both sex morphs. The trees at higher local population density sites suffered higher seed mortality due to predation and decay, and tended to produce smaller seeds. Thus, the impacts of local population density operated both positively and negatively on reproduction. As a factor of individual traits, tree size scarcely affected any demographic processes. On the other hand, sex morph did affect pollination success. Trees of PG type had lower immature seed fall than those of PA type, suggesting that the former has higher efficiency of pollen acceptance than the latter. The results on seed demography presented here partly support previous suggestions that heterodichogamous plants exhibit reciprocal cross-pollination and gender specialization as reproductive traits.

SummaryWe examined the relationship between flower preference and the spatial distribution of two Bombus species in a traditional agro-forestry Satoyama landscape where human activities maintain a mosaic of landscape units, including old-growth and secondary forests, conifer plantations, cutover lands (stands 5–7 years after clear-cutting of secondary forests), and paddy fields. Bombus ardens prefers shallow woody flowers, whereas B. diversus tends to forage on herb flowers with long corolla tubes. Bumble bees were collected by window traps at seven types of landscape units. Most B. ardens individuals (77%) were caught at upper forest strata of old-growth stands. B. diversus queens displayed a similar preference for old-growth stands, whereas approximately half of the workers were captured in open land, such as cut-over land and paddy fields. These findings suggest that B. ardens mainly uses old-growth forests, where woody species diversity and woody flower abundance is high, whereas B. diversus visits fo...

In order to evaluate the consequences of forest fragmentation on populations of Magnolia obovata, we compared genetic diversity and reproductive characteristics at two nearby sites, one conserved and one fragmented. The genetic diversity between adults trees of the different sites was not significantly different. However, saplings in the conserved site showed a significantly higher genetic diversity than both adult trees in the conserved site and saplings in the fragmented sites; this was found to be the result of the larger gene flow into the conserved site. The density of the adult trees was significantly related to all of the reproductive traits analyzed (fertilization of ovules, insect attack to seeds, ovules that developed into seeds and outcrossing at the stage of seeds) at both sites. At both sites, fertilization of ovules and insect attack on seeds were positively correlated to adult tree density while outcrossing rate was negatively correlated to adult tree density. The fertilization of ovules and outcrossing were more dependent on adult tree density in the fragmented site than in the conserved site. The probability of ovules developing into outcrossed seeds showed a negative correlation with adult tree density at both sites, indicating the advantage of low density for this species and possibly implying a resilience to habitat fragmentation. A two-generation-analysis did not identify significant differences between sites in terms of the structure of the pollen pool and the number of pollen donors. Although fragmentation affected reproductive characteristics, the effect on seedling establishment and subsequent survival remains to be determined. Proposals for future studies that will assist in the development of management strategies for forests suffering fragmentation are made.

To understand how a sparsely distributed species can maintain viable populations, and with a particular interest in distance-dependent reproductive success, we investigated the ovule survival and the factors that determine the survival for sparsely distributed Kalopanax pictus (Araliaceae) in a temperate forest landscape around the Ogawa Forest Reserve, central Japan. We found 154 potentially mature trees (>20 cm diameter at breast height) in a 600-ha site. The year 2000 was a mass flowering year for K. pictus; 96.8% of the trees examined flowered in that year; however, this was less than half of the trees that flowered in other years. The flowers of K. pictus include protandrous inflorescences, which bloom on individual tress in midsummer when few other tree species bloom. We conducted pollination experiments with out-crossed, self-pollinated, bagged, and control inflorescences. Results suggest that self-pollination is limited, partially by low self-compatibility and partially by protandry. Ovule survival from the flower to the seed stages was not dependent on the temporal flowering density of conspecific adults. The flowering habit and presence of effective pollinators may allow K. pictus to avoid the negative effects of sparse distribution on pollination efficiency. However, ovule survival during the ovary development stage depended on infection by a species-specific fungus, Mycosphaerella acanthopanacis. The fungus damages leaves, and the infection intensity depends on the distance between conspecific K. pictus adults. Thus, an advantage of sparse distribution in K. pictus is disease avoidance, whereas its disadvantages are overcome by pollination efficiency.

This data paper reports census data of ground-dwelling beetle and other fauna of the forest floor environment; collections were made from a network of 22 forest sites in Japan. To our knowledge, this represents the largest dataset for long-term monitoring of a ground-dwelling beetle community and other taxa in a ground environment in forests, which covers a broad climatic range in the temperate zone and is freely available. The network forms part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subalpine, cool- and warm-temperate and subtropical climatic zones and the four major forest types of Japan. Thirty-three permanent plots usually 1 ha in size were established in old-growth, secondary natural and a few plantation forests. Censuses of the ground-dwelling beetle community were conducted using pitfall trapping and forest floor environment monitoring every year from 2004 to the present. During the initial 9 years of the census (2004–2012), 59,762 beetle individuals (including 3182 larvae) of more than 314 species were recorded. This dataset includes taxonomy and biomass of each beetle individual and each taxonomic group of other invertebrates coincidently captured in pitfall trapping. The dataset also includes data related to ground coverage by forest floor vegetation, dry mass of the accumulated organic litter layer, and carbon and nitrogen contents and cellulose decomposition rate in organic layer and surface mineral soil. The data could be used to investigate geographical patterns and intra- and inter-annual dynamics of individual body mass, populations and community structures of ground-dwelling beetles, and their relationships with the forest floor environment. Furthermore, the data could be analyzed with other open datasets related to tree community dynamics and litter fall continuously measured in the same study plots. This dataset also provides information related to the distribution and average body mass of each beetle species.

The response of forest floor vegetation and regeneration of major treespecies to deer exclusion in a riparian forest were studied for 3 years withtheinteractive effects of natural disturbances. At the start of this study, deerdensity had quickly increased to a fairly high level (29–31 individualskm−2) during the last decade and had severely reduced theamount of forest floor vegetation in the study area. Dwarf bamboos, which weredominant before, had almost diminished from the forest floor. During the studyperiod, aboveground biomass increased steadily but species diversity did notchange much in the exclosures. Outside the exclosures, the seedlings of alltreespecies were damaged greatly by deer browsing, especially the taller ones. Deerbrowsing had little effect on the emergence of tree seedlings, but deertrampling might have accelerated emergence indirectly by disturbing the soilsurface for some species. Differences in plant responses were also observed fordeer browsing and the presence of dwarf bamboo that strongly inhibits therecruitment of tree seedlings. The nine major species were classified intothreegroups according to the response of seedlings to deer browsing and disturbance.Group 1 consists of the species whose seedling survival is affected bybrowsing,but seldom by disturbances (Phellodendron amurense,Kalopanax pictus, Quercus crispulaandMalus toringo). Groups 2 and 3 consist of species adaptedto tree-fall disturbance (Betula spp.) and ripariandisturbance (Alnus hirsuta var.sibirica, Ulmus davidiana var.japonica, Populus maximowiczii andSalix sachalinensis), respectively, and seedling survivalof these two groups is principally affected by light conditions. The effect ofdeer browsing on seedling survival and growth was greater for Group 2 than forGroup 3.

Receptor activator of NF-kB (RANK) and its ligand, receptor activator of NF-kB ligand (RANKL) play a crucial role in the differentiation and activation of osteoclasts. In order to evaluate the efficacy of RANK, we designed a soluble murine RANK (sRANK) and compared its functional activitywith Osteoprotegerin (OPG), a soluble decoy receptor for RANKL. sRANK was expressed in baculovirus-infected Sf-9 cells and purified by Ni-NTA chromatography followed by MonoQ column elution. The binding affinity of the purified sRANK to RANKL was quite similar to that of OPG. Furthermore, the inhibitory effect on RANKL-induced osteoclastogenesis from mouse bone marrow cells showed no significant difference between sRANK and OPG. However, sRANK had no effect on TNF-related apoptosisinducing ligand (TRAIL) -induced apoptosis, although OPG prevented the cytotoxic activity of TRAIL. The results of this study suggest that recombinant sRANK may have therapeutic value as an inhibitor of bone resorption.

To investigate synchronized annual fluctuation of seed production and its advantage for regeneration at the community level, for nine years (1987–1995) we monitored the flowering, seed production, and seedling emergence of the 16 principal tree species in a temperate deciduous forest, Ogawa Forest Reserve, in central Japan. We found that the species with higher synchronized flowering within a population had larger fluctuation of annual seed production at the population level. The coefficient of concordance of flowering and the coefficient of variation of annual seed production were continuously distributed among species, making it difficult to distinguish masting from nonmasting species. The annual seed production patterns of the 16 species were classified, by cluster analysis, into groups that synchronize their fluctuation of annual seed production. This analysis showed a highly synchronized annual seed production, not only among congeneric species, but also among species of different families. Although our results have some insufficiency of statistical significance, they did show that predator satiation, both in a population and a guild, effectively operated for many species to enhance seed survival at the pre-dispersal stage. They also showed that pollination efficiency was likely to be operating at the population level for half of the wind-pollinating species. However, generalist predator satiation at the postdispersal seed stage may not operate in a simple, detectable manner in this species-rich forest community. It is highly probable that there are combined effects of several factors: limited weather triggers for flowering, common flowering physiology among taxonomically related species, and the ecological advantages at the population and guild levels, may cause multiple species to have synchronized fluctuation patterns of seed production.

The mechanism controlling the disappearance of osteoclasts from bone surfaces after bone resorption in vivo is largely unknown. This is because there is no suitable experimental system to trace the final fate of osteoclasts. Here, we used an experimental model of tooth movement in rats to show that preexisting osteoclasts disappeared from the bone surface through apoptosis during a force-induced rapid shift from bone resorption to formation. On the distal alveolar bone surface of the maxillary molar in growing rats, many mature osteoclasts were present. When light tensional force was applied to the bone surface through an orthodontic appliance, these preexisting osteoclasts gradually disappeared. One day after the application of force, about 24% of the osteoclasts exhibited apoptotic morphology and the proportion of apoptotic cells was increased to 41% by day 2, then decreased afterward. These changes were undetectable on the control distal alveolar bone surface, which is free from tensional force. As shown by in situ hybridization, a marked increase in transforming growth factor beta1 (TGF-beta1) and osteoprotegerin (OPG) messenger RNA (mRNA) was observed in the stretched cells on the tensioned distal bone surface, simultaneously with the loss of osteoclasts. Both of these factors are known to have a negative effect on osteoclast recruitment and survival. As early as 2 days after force application, some of these stretched cells were identified as cuboidal osteoblasts showing intense signals for both factors. Our data suggest there may be a sequential link in tensional force applied on the bone lining cells, up-regulation of TGF-beta1/OPG, and disappearance of osteoclasts.

Treatment with NO-releaser NOC18 significantly promoted apoptosis in murine osteoclast-like cells, with a transient increase in caspase-3-like protease activity. In contrast, the apoptosis was protected against by caspase inhibitors, most efficiently with the broadly acting caspase specific inhibitor z-Asp-CH2-DCB, indicating involvement of multiple caspases in progression of the apoptosis. Among osteoclast survival factors examined, calcitonin completely protected against morphologically defined-apoptosis and the increase of caspase-3-like protease activity. The effect of calcitonin was mimicked by treatment of cells with (Bu)2cAMP and forskolin, and abolished by protein kinase-A inhibitor H-89. Independently from the PKA activation, colony stimulating factor-1, interleukin-1β and the receptor activator of NF-κB ligand also protected against the apoptosis but were less effective than calcitonin. All survival factors investigated inhibited conversion of procaspases-3 and -9 to their mature forms in the ce...

The present study demonstrates that loss of cell adhesion potently promotes apoptosis in osteoclasts, a process termed "anoikis." When purified mature rabbit osteoclasts were cultured on plastic for 18 h, about 25% of them were spontaneously committed to apoptosis. The death rate increased more than twofold, after osteoclasts were subjected to suspension culture in inverted Terasaki plates. The osteoclast anoikis was significantly prevented by bongkrekic acid, an inhibitor of mitochondrial permeability transition (PT), and z-VAD-FMK, a caspase inhibitor, suggesting involvement of mitochondrial PT and caspase activation in the death process. Colony-stimulating factor-1 (CSF-1), receptor activator of NF-kappaB ligand (RANKL), and calcitonin protected adherent osteoclasts, but not floating osteoclasts from anoikis. These data show that adhesion is a primary requirement for osteoclast survival.

Population structure and ecological characteristics of component species of a riparian Ulmus-Quercus forest in central Japan were analyzed with special reference to riparian disturbance regime. Though the dbh distribution of the whole community was L-shaped, those of several component tree populations had several modes, suggesting intermittent regeneration periods in the past. Correlation of spatial distributions among tree populations and subpopulations showed 6 major groups reflecting riparian disturbances in the past and different establishment patterns among species. A cluster of small-sized tree populations (Salix sachalinensis, Alnus hirsuta and Populus maximowiczii

Seed-bank dynamics ofC. controversa, a common tree in Japanese temperate forests, were investigated at Ogawa Forest Reserve by direct measurement of seed input, soil seed density, and seedling output (germination of soil seeds), together with two field experiments on postdispersal seed mortality. Soil seed density varied from 4 to 233 m−2in the site near conspecific adults (−2in far sites (≥5 m) during the 1988–92 period. Seed input occurred only in 1988 and 1990: 190–740 m−2at the sites near conspecific adults, and 4–20 m−2at the far sites. Seedling output was observed every year and accounted for 0–15% of the loss from the seed bank, occasionally 30–60%. Seeds buried at 5-cm depth suffered moderate mortality (c.0.2 year−1) by fungal pathogens. In contrast, seeds experimentally placed on the ground suffered higher mortality (0.5–1 year−1) through predation by ground mammals, probably wood mice. In the experiment, seeds whose mesocarp was removed survived much better. On the other hand, distance itself did not appear to affect post-dispersal mortality of seeds. Seeds in canopy gaps also tended to suffer higher mortality. Current spatial pattern and mode of seed dispersal should decrease the potential ability of the seed bank of this species to colonize safe sites. Rare and unpredictable events might increase the contribution of the seed-bank strategy to regeneration in this forest.

To test two hypotheses for mast fruiting, i.e., (1) pollination efficiency and (2) pre-dispersal predator satiation, we investigated annual fluctuation in seed production and demography from flower to seed of four Carpinus species (family Betulaceae). We monitored flowering, seed production, and seed fall for seven years (1987-1993) for Car- pinus laxiflora, C. tschonoskii, C. japonica, and C. cordata, which co-occur in a temperate deciduous forest, Ogawa Forest Reserve, central Japan. We also monitored the seasonal development of pistillate aments in 1995. These Carpinus species are known to show highly synchronized, fluctuating annual seed production. Total seed production (the sum of sound seeds, seeds suffering predation, empty seeds, and immature seeds) was proportional to the quantity of staminate aments and was synchronized among the four species during the observation period. The percentage of mature seeds (the sum of sound seeds and seeds suffering predation) out of the total seed production was positively correlated with annual staminate ament production. This result supports the pollination efficiency hypothesis. The observation that most ovaries in this study did not fall after the pollination season and grew into normal, mature-sized seeds irrespective of fertilization (empty or not) also sup- ports the hypothesis. The percentage of seeds suffering predation by insects significantly decreased in relation to sound seed production, suggesting that predator satiation also operated for these Carpinus species. If the four species have common seed predators (pos- sibly some curculionid species), mutually synchronized fluctuation of seed production among them would be effective for escaping from pre-dispersal predation.

We observed seed (or diaspore) dispersal of six species (4 species of Betulaceae, 2 species of Aceraceae) for 5 years in a species-rich deciduous broad-leaved forest (Ogawa Forest Reserve, central Japan), and explained the observed patterns with a mechanistic model of dispersal. The model involves three parameters which can be biologically interpreted; terminal seed velocity (F), tree height (H), and amount of dispersed seed per reproductive individual (Q).The relationship between dispersed seed density and distance from a single seed source were explained well by the model. Two dimensional distribution of seed density dispersed from multiple seed sources was approximated by the model. We evaluated the dispersal success in reaching safe sites as the gap area covered by a given seed density, and discussed the adaptive meaning of the dispersal traits based on the model and empirical data. While Fdid not vary greatly among the species, Qshowed greater variation among the species in this forest. The ...

In order to clarify regeneration traits and their fitness, we compared seed fall, seedling emergence, and first-year seedling survival of four co-occurring species, Carpinus tschonoskii, C. japonica, C. laxifiora, and C. cordata, in an old-growth temperate deciduous forest in Ogawa Forest Reserve, central Japan. Seedling emergence ratio of C. cordata (5.5%), whose seeds mostly germinated 1.5 yr after seed fall, was lower than the other species (8.5-11.2%). First-year seedlings of Carpinus tschonoskii and C. japonica had much lower survival rates (2.7%, both species) than C. laxifiora and C. cordata (7.5- 8.5%) under closed canopy, suggesting that the former two are more disturbance dependent than the latter two. They are characterized by their seed and seedling performances as seed rain type fundamentally; however, C. cordata and C. laxiflora are able to establish a seedling bank, and C. cordata has a seed bank too. These regenerative strategies partly explain the abundance and population structure of the four species in this old-growth forest. Multiple regression analyses showed that topography was important for survival of all species but C. cordata. This result was consistent with the adult distribution of these species in this forest. Wind dispersal of Carpinus is effective, both to escape from density- or distance- dependent high mortality and to increase the chance of arriving at canopy gaps, where seedling survival rate is high. However, escaping high mortality seems relatively more important for C. laxifiora and C. cordata (seedling bank strategy), and arriving at a canopy gap is relatively more important for C. tschonoskii and C. japonica (seed rain strategy).

It is essential to investigate both the spatio-temporal pattern of seed dispersal and the subsequent fate of offspring to evaluate the effect of dispersal on plant fitness. This paper examines the ...

カテプシンDとEは, 主要な細胞内アスパラギン酸プロテアーゼである。本研究は, 両酵素の細胞内での活性調節機構を検索する目的で, 動物種や組織などの由来を異にする酵素を用いて, ATPや他のヌクレオチドによる酵素活性の上昇について比較, 検討を行った。ウシおよびラットカテプシンDは, ATPや他のヌクレオチド存在下では, ウシ血清アルブミンを基質としたときに顕著な酵素活性の上昇が認められ, AMP-PCP存在下でも酵素活性の上昇が認められた。ウシヘモグロビンや合成基質を用いたときは, アルブミンほどの酵素活性の上昇は認められなかった。一方, ヒト赤血球およびラット脾臓カテプシンEは, ヘモグロビンを基質としたときのみ, ATPや他のヌクレオチド存在下にて酵素活性の上昇が認められた。さらに, ATPは, カテプシンEの熱安定性を顕著に上昇させ, 酵素分子を安定化することが明らかとなった。

Forest community dynamics were studied for 4 years in a 6 ha permanent plot of species rich, old-growth, temperate deciduous forest in Ogawa Forest Reserve, central Japan. The gap formation rate, recruitment, mortality, gain and loss rate in basal area during 4 years were 42 m2 ha−1 yr−1, 1.74% yr−1, 1.19% yr−1, 1.12% yr−1 and 0.88% yr−1, respectively. The turnover time calculated from them ranged from 58 to 240 years. Both the mortality and mortality factors were size dependent; trees in middle size class had smallest mortality, and the proportion of the trees killed by disturbances increased with size. Gap creations were concentrated in a particular year, suggesting a large heterogeneity in time. Spatial distribution of recruited trees were biassed to the old gaps (older than 4 years), especially that of the species with Bell-shaped dbh distribution (shade intolerant) strongly associated with the gaps. Recruitment in tree stems and the loss of basal area, thus had the larger variability than mortality of stems and this forest, and the species with L-shaped dbh distribution seemed to going to increase the importance in the future if the present trend continues to be held. The turnover time of population is positively correlated with the maximum dbh size of the species, indicating the slow change of the population of large sized species.

Pepstatin A is well known to be an inhibitor of aspartic proteinases such as pepsin, cathepsins D and E. Except for its role as a proteinase inhibitor, however, the pharmacological action of pepstatin A upon cells remain unclear. In this study, we found that pepstatin A suppressed receptor activator of NF-kappaB ligand (RANKL)-induced osteoclast differentiation. Pepstatin A suppressed the formation of multinuclear osteoclasts dose-dependently. This inhibition of the formation only affected osteoclast cells, i.e., not osteoblast-like cells. Furthermore, pepstatin A also suppressed differentiation from pre-osteoclast cells to mononuclear osteoclast cells dose-dependently. This inhibition seems to be independent of the activities of proteinases such as cathepsin D, because the formation of osteoclasts was not suppressed with the concentration that inhibited the activity of cathepsin D. Cell signaling analysis indicated that the phosphorylation of ERK was inhibited in pepstatin A-treated cells, while the phosphorylation of IkappaB and Akt showed almost no change. Furthermore, pepstatin A decreased the expression of nuclear factor of activated T cells c1 (NFATc1). These results suggest that pepstatin A suppresses the differentiation of osteoclasts through the blockade of ERK signaling and the inhibition of NFATc1 expression.

alpha 2-Macroglobulin (alpha 2M) is an abundant glycoprotein with the intrinsic capacity for capturing diverse proteins for rapid delivery into cells. After internalization by the receptor- mediated endocytosis, alpha 2M-protein complexes were rapidly degraded in the endolysosome system. Although this is an important pathway for clearance of both alpha 2M and biological targets, little is known about the nature of alpha 2M degradation in the endolysosome system. To investigate the possible involvement of intracellular aspartic proteinases in the disruption of structural and functional integrity of alpha 2M in the endolysosome system, we examined the capacity of alpha 2M for interacting with cathepsin E and cathepsin D under acidic conditions and the nature of its degradation. alpha 2M was efficiently associated with cathepsin E under acidic conditions to form noncovalent complexes and rapidly degraded through the generation of three major proteins with apparent molecular masses of 90, 85 and 30 kDa. Parallel with this reaction, alpha 2M resulted in the rapid loss of its antiproteolytic activity. Analysis of the N-terminal amino-acid sequences of these proteins revealed that alpha 2M was selectively cleaved at the Phe811-Leu812 bond in about 100mer downstream of the bait region. In contrast, little change was observed for alpha 2M treated by cathepsin D under the same conditions. Together, the synthetic SPAFLA peptide corresponding to the Ser808-Ala813 sequence of human alpha 2M, which contains the cathepsin E-cleavage site, was selectively cleaved by cathepsin E, but not cathepsin D. These results suggest the possible involvement of cathepsin E in disruption of the structural and functional integrity of alpha 2M in the endolysosome system.

This data paper reports litter fall data collected in a network of 21 forest sites in Japan. This is the largest litter fall data set freely available in Japan to date. The network is a part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subarctic to subtropical climate zones and the four major forest types in Japan. Twenty-three permanent plots in which usually 25 litter traps were installed were established in old-growth or secondary natural forests. Litter falls were collected monthly from 2004, and sorted into leaves, branches, reproductive structures and miscellaneous. The data provide seasonal patterns and inter-annual dynamics of litter falls, and their geographical patterns, and offer good opportunities for meta-analyses and comparative studies among forests.

When plants start to reproduce (when they reach a certain size or the age of onset of flowering and fruiting), how often and how many of the plants produce offspring during their lifetime (frequency of reproduction) and how many offspring are produced in a year (magnitude of reproduction) are important factors of plant demography, because these factors determine the lifetime fecundity of the plants. Concerning the critical size of reproduction of plants, many studies have been conducted for herbaceous perennials and monocarpic species. There are intraspecific variations in the size of reproductive individuals, and it has been pointed out that not only the size but also the growth rate of individual plants relate to the timing of their reproduction (Reekie et al. 1997; Wesselingh et al. 1997). Several models of the critical size of reproduction that take into account growth rate (Kohyama 1982; Nakashizuka et al. 1997) show that both size and growth rate affect the resource. Differences in reproductive traits are important factors contributing to the ability of tree species to coexist in a forest (Kohyama 1993; Thomas 1996). However, the long life span, large individual size, and diverse environmental conditions of tree habitats make it difficult to analyze and model the reproductive traits of tree species in a forest community. It is important to construct a simple model of the critical conditions of reproduction of tree species based on empirical data to understand tree life histories and coexistence mechanisms in a forest community.

Glycosphingolipids and their metabolites play important roles in a variety of biological processes. Several signal molecules are localized in a glycolipid-enriched microdomain on the cell surface, and their signals are regulated by the glycolipid composition. However, the function of glycolipids in osteoclastogenesis has not been clearly understood. We found that D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), a glucosylceramide synthase inhibitor, completely inhibits the osteoclast formation induced by macrophage-colony-stimulating factor and receptor activator of nuclear factor-kappa B ligand (RANKL) in a dose-dependent manner. Expression of RANK, the receptor of RANKL, induced by macrophage colony-stimulating factor, was reduced markedly in D-PDMP-treated cells. d-PDMP also inhibited the phosphorylation of the inhibitor of nuclear factor-kappa B and extracellular signal-regulated kinase 1/2 induced by RANKL. In several experiments with the addition of glycolipids to D-PDMP-treated purified bone marrow cells, lactosylceramide (LacCer) strongly affected the differentiation into tartrate-resistant acid phosphatase mononucleated cells, but not positive multinucleated cells. GM3 and GM1 also recovered, but less effectively compared with LacCer. Moreover, exogenous LacCer recovered the reduced expression of RANK and the phosphorylation of inhibitor of NF-kappa B and extracellular signal-regulated kinase 1/2 after stimulation by RANKL at the same level of cells without D-PDMP treatment. Our data suggest that glycosphingolipids, especially LacCer, are necessary for the initiation step of RANKL-induced osteoclastogenesis.

Tooth cementum, a calcified hard tissue covering the root surfaces, is an important component connecting the teeth to the collagenous fibres of the periodontal ligament. Although the overall composition of cementum may closely resemble that of bone, each part has not been fully characterized. Here, the localization of the matrix gamma-carboxyglutamic acid (Gla) protein (MGP), one of the major Gla-containing proteins in the body, in cementum was investigated using immunohistochemistry and in situ hybridization. (1) Strong MGP antigenicity was observed in the acellular cementum, but was only moderate in the cellular cementum; (2) polygonal periodontal ligament cells facing the acellular cementum and the uncalcified cellular cementum expressed MGP mRNA, indicating that these cells produced MGP and deposited it on the cementum; (3) MGP accumulated at the junction between the uncalcified and calcified cellular cementum; and (4) the distribution pattern of MGP antigenicity resembled that of osteopontin. As one function of MGP could be as a negative regulator for mineral apposition, the expression of MGP in the cells adjacent to the cementum may be important to prevent hyperapposition of minerals.