Vegetation history since the last glacial period in the Mikata lowland,the Sea of Japan area,western Japan

Local and regional vegetation since the last glacial period was reconstructed on the basis of a palynological study of sediment at Iwaya, in the Sea of Japan area, western Japan. During the interstade (before about 30 000 years BP), forests were composed predominantly ofCryptomeria japonica withTsuga sieboldii and cool-temperate deciduous broad-leaved trees. In the pre-full-glacial, the full-glacial and the early late-glacial (30 000-12 000 years BP), forests were dominated by temperate (montane) and boreal (subalpine) Pinaceae andBetula. During the early full-glacial, the pinaceous forests were mixed with cool-temperate trees such asFagus crenata. In the late full-glacial (18 000-16 000 years BP), the maximum development of pinaceous conifer forests was recognized. Cool-temperate broad-leaved forests composed mainly ofF. crenata andQuercus (Lepidobalanus) replaced the pinaceous forests at about 12 000 years BP and were maintained to the early postglacial.Cryptomeria japonica was distributed around the Mikata lowland during the last glacial.Cryptomeria japonica, which began to increase at 16 000 years BP, increased abruptly in the early postglacial and spread throughout the postglacial in the lowlands. After 6300 years BP, lucidophyllous forests composed mainly ofQuercus (Cyclobalanopsis) andCastanopsis were established in the Mikata district; this was later than in the inland and the Pacific Ocean areas in the Kinki region, western Japan. In historic times (afterca 2000 years BP), secondary forest ofPinus densiflora, which can grow as a pioneer in disturbed habitats, spread.     

Mitochondrial phylogeography of the Japanese pond turtle,Mauremys japonica (Testudines,Geoemydidae)

The phylogeography of the Japanese pond turtle, Mauremys japonica (Temminck and Schlegel, 1835), which is an endemic species in Japan, was studied by analyzing the variation in two mitochondrial DNA sequences, the cytochrome b gene and the control region. These analyses suggest that M. japonica comprises two major groups. The first one was found in the more eastern region, eastern Honshu Island and Shikoku Island, while the second was found in a western region, Kyushu Island and the Chugoku District (the westernmost part of Honshu Island). The boundary between the two groups is located in the Chugoku District. The nucleotide and haplotype diversities were very low, and these low diversities seem to have been caused by a bottleneck in the last glacial age. These results suggest that this species survived the last glacial period in two refugia, one in the central part of Honshu Island and the other one in Kyushu Island. Subsequently, population expansion took place in the postglacial period, and the groups from the two refugia extended their distribution ranges to the present boundary in the Chugoku District which represents a secondary contact zone.     

On the distributional limits of the lucidophyllous forest in the Japanese Archipelago

The distribution of the lucidophyllous forest and its transition to the summergreen broadleaf forest were studied in relation to such environmental factors as temperature and precipitation. The distribution is primarily affected by low temperatures during winter and secondarily by precipitation and sea wind. The upper and northern limits of the forest most closely correlated with the coldness index within four thermal indices. Because of much snow, the forest is more suppressed at a lower altitude in the region with high snowfall than in other regions. The area at its upper limit is dominated by the evergreenQuercus forest while the area at its northern limit is occupied by thePersea forest. Moreover, CI values in these distributional limits are significantly different. This phenomenon appeared to result from the resistance ability of dominant lucidophyllous trees not only to the thermal conditions but also to sea wind. In both the region with high snowfall and the region with high rainfall there is a zone where the evergreenQuercus forest overlaps theFagus crenata forest. In contrast, in the region with little rainfall, these two forests do not overlap but form a gap dominated by forests such as theFagus japonica forest. Thus, precipitation factors largely affect the altitudinal forest zones in Japan.     

Ecological Aspects of the Downstream Migration of Introduced European Eels in the Uono River, Japan

We examined the species composition, timing of downstream migration, and biological characteristics of eels using catches at three commercial weirs from 1996 to 1998 in the Uono River, Niigata Prefecture, Japan, which is located farther north in the Japan Sea than where most Japanese eels, Anguilla japonica, recruit. Analyses of a sub-sample of the 292 eels caught in the weirs found that 93.6% were introduced European eels, Anguilla anguilla, that were sexually maturing silver phase eels. Their average age based on otolith annuli was 10.2 years, indicating a relatively high average growth rate of 6.3 cm year^–1. Catch records in 1996 and 1997 indicated that downstream migration occurred sporadically from the middle of August to the end of November and that catches generally coincided with abrupt increases in water discharge and drops in water temperature. The highest catches in both years occurred between the last quarter and new moon. These findings were similar to studies on this species in Europe and indicate that A. anguilla can grow rapidly, begin maturation, and start downstream migration far from its native range. This discovery of introduced eels initiating their spawning migration at the same time as A. japonica raises concerns about the potential impact of interbreeding between species and the possible effects on the fishery resources of A. japonica.     

Comparison of ecophysiological responses to heavy snow in two varieties ofAucuba japonica with different areas of distribution

Aucuba japonica varieties are common evergreen understory shrubs in Japan.Aucuba japonica var.borealis is distributed on the Sea of Japan side of Honshu and Hokkaido where heavy snow cover lasts for more than 3 months in winter.Aucuba japonica var.japonica is distributed in areas with shallow or no snow on the Pacific Ocean side of Honshu and Shikoku. The ecophysiological characteristics of var.borealis were compared with those of var.japonica to examine the effects of heavy and long-term snow cover on the life cycle of var.borealis. Shoots of both varieties were shaded in crushed ice for 110 days, but their photosynthetic activities, chlorophyll contents and the chlorophylla/b ratio was not affected. The leaves of var.borealis were no less frost tolerant than those of var.japonica. In spite of the difference in environmental factors, both varieties had similar characteristics in seasonal changes of photosynthesis, respiration and chlorophylla/b ratio. These results suggest that var.japonica could survive in areas with heavy snow where it does not normally occur. Leaf net production (LNP) was estimated based on the microclimatic data and seasonal photosynthetic and respiration rates. The difference in the annual LNP between the two varieties was equivalent to the difference in the LNP during the snow season. One of the major effects of snow cover is to interrupt and reduce the production period of var.borealis.     

Snowcover as a factor controlling the distribution and speciation of forest plants

Effects of climatic factors on plant distribution in the Chubu District, central Japan, were examined with direct gradient analysis. The distribution of many species was controlled not only by temperature but also by snowfall.Sasa kurilensis, Heloniopsis orientalis andTripterospermum japonicum preferred snow regardless of the thermal conditions. The snow seemed to exert more influence on endemics than on the more widespread plants, on evergreen plants more than on deciduous plants, and on trees or shrubs more than on herbs or climbing plants. Thus, the snow factor contributes to the high endemic ratio of central Japan. Among the snow-tolerant evergreen shrubs there were many neo-endemics derived from snow-intolerant parent populations of the species which have restricted distributions in the laurel forests. They could occupy habitats in the summergreen forests, where their life form can withstand heavy snowfall. Because of the heavy snowfall on the Sea of Japan side of central Japan in the postglacial period, evergreen coniferous trees have lost many of their previous habitats since most of them are intolerant of heavy snowfall.     

Classification and phytogeographical differentiation of oriental beech forests in Turkey and Bulgaria

Floristic differentiation of the oriental beech (Fagus orientalis Lipsky) forests in Turkey and Bulgaria was investigated and the role of geographical and topographical factors in this differentiation was assessed. After geographical and ecological stratification of the available 922 relevés, 288 remained. Classification, by applying cluster analysis, resulted in seven vegetation units defined by species composition which represent the geographical and ecological variation of Fagus orientalis forests. DCA ordination was applied to these units by passively projecting their chorological structure, as supplementary variables. For more detailed interpretation of vegetation types with similar geographic distribution patterns, PCA was applied by passively projecting the chorological elements, life-forms and topographical factors as supplementary variables. Seven vegetation units representing the geographical and ecological variety of Fagus orientalis forests were described. Four vegetation units represent the core area of Fagus orientalis distribution on the western and middle coast of the Black Sea region (Euxine region); the remaining three types represent the distribution in the eastern Black Sea region (Colchic region), the distribution in western and southern Anatolia under the influence of the Mediterranean climate and the distribution in the transitional zone from the Euxine region to the continental parts of Inner Anatolia, respectively. The four vegetation types in Euxine region reflect the decreasing effect of Black Sea towards Inner Anatolia, as well as altitudinal differences, except the forest type representing forests on calcareous sites. The other three vegetation units represent ravine, lowland to montane and altimontane forests in Euxine region. Fagus orientalis forests could be distinguished by their floristic composition, their chorological elements and life-forms spectra, which reflect a geographical and ecological gradients.     

Ecological geography of the range of theAbies mariesii forest in northeast Honshu,Japan, with special reference to the physiographic conditions

In the subalpine areas of the snowy regions of Japan (the Japan Sea side), there are some mountains with no or very small stands ofAbies mariesii, although this species dominates the subalpine coniferous forests of the region. In order to discuss the cause and process of this phenomenon, present horizontal and vertical ranges, as well as physiographic conditions, of theA. mariesii forest were examined in detail on the mountains in the Tohoku District. Sites in the subalpine zone were classified into two types: ‘azonal sites’ which should be excluded from the habitat ofA. mariesii because of their edaphic or small-scale climatic properties, and ‘zonal sites’. Mountains with vast less-inclined zonal sites generally had well developed stands ofA. mariesii forest. On the mountains with only small, solitary stands ofA. mariesii, the distribution was limited to flats or slightly inclined slopes at relatively low altitudes. These less-inclined zonal sites were regarded as an important habitat for theA. mariesii forest in the Hypsithermal period and the extent of these sites controls the extent of the stands in that period and the success of the subsequent range expansion of the forest.     

Diffusion of Fe(II) from an iron propagation cage and its effect on tissue iron and pigments of macroalgae on the cage

Iron propagation cages were settled on sand and/or rock beds in coastal areas of Hokkaido. The cage was oxidized by dissolved oxygen and the released Fe(II) diffused into the seawater around the cage. Fe(II) concentrations in the range of 10–50 nM were detected within a 20-m distance around the cage. For comparison, in the Japan Sea, the total iron concentration is less than 2 nM.Laminaria japonica was grown in an indoor semi-continuous culture system. The critical Fe level for maintaining maximum growth, and the subsistence Fe level for survival were measured. The concentrations obtained were 14–21 and 8 g Fe g^–1 tissue, respectively. Iron found inL. japonica growing on rocks and/or rock beds in the Japan Sea was close to the subsistence level. However, the Fe level inL. japonica on the cage in the Japan Sea was considerably higher. The concentrations of chlorophyll-a and fucoxanthin collected from the cage were significantly higher for sporophytes, demonstrating that iron is a very important element for the growth of seaweeds.     

Genetic diversity of fragmented populations of<Emphasis Type="Italic"> Polygala reinii</Emphasis> (Polygalaceae), a perennial herb endemic to Japan

Genetic variation at 10 allozyme loci was analyzed in 14 populations of Polygala reinii (Polygalaceae), a perennial herb endemic to central Honshu, Japan, with a fragmented geographical distribution. The levels of genetic variation within species (P=80.0, A=3.10, H_E=0.303) and within populations (P=42.1, A=1.61, H_E=0.163) were considerably higher than the mean for other endemic plants or short-lived perennial herbs. Genetic differentiation among populations was also high (G_ST=0.404). The genetic distance phenogram tended to show a clustering of the populations reflecting the fragmentation of the species range. A principal component analysis revealed the same tendency, as well as three groupings of populations in the Tokai district, on the Kii Peninsula and in the northern Kinki district. A negative correlation was obtained between the levels of gene flow and geographical distance among the populations (r=–0.745, P<0.0001). These results indicated limited gene flow among populations in P. reinii, presumably due to the geographical isolation accompanying the fragmented distribution. On the other hand, the geographical differentiation between the Japan Sea and Pacific Ocean sides was found in P. reinii, suggesting the influence of postglacial migration on the establishment of the genetic structure of this species.     

Predicted potential distribution of Sydowia japonica in Japan

Sydowia japonica, a dothidealean fungus, is a parasite that is specific to the male strobili of Japanese cedar. The fungus is a candidate for the control of Japanese cedar pollen dispersal, which is a cause of pollinosis. To evaluate S. japonica for bioherbicidal applications, it is necessary to characterise its potential distribution and environmental niche. Here, we predicted the distribution of S. japonica in Japan using field surveys and a maximum entropy model, and identified the environmental variables that influence its distribution. We identified S. japonica from a total of 87 localities in Japan through field surveys. Based on presence data and associated environmental variables, our model predicted that S. japonica is widely distributed in Japan, but concentrated in the Hokuriku and Kinki areas along the Sea of Japan. The model also predicted that the most important environmental variables influencing fungal distribution were sunshine duration in the winter and precipitation in the summer. This new information will contribute to the development of bioherbicidal applications for S. japonica.     

A Finding of the Crab Planes marinus Rathbun, 1914 (Decapoda: Grapsidae) in Peter the Great Bay,Sea of Japan

A crab Planes marinus Rathbun, 1914 was found on a drifting buoy in Peter the Great Bay (Sea of Japan). The crab probably arrived in the bay with subtropical waters penetrating into this area during the summer period.     

Live crown tops of Japanese cedar (Cryptomeria japonica) approach one another in height at urban forest sites

Since the 1980s, we have found Japanese cedar, Cryptomeria japonica (L. f.) D. Don, trees with crown tops affected by dieback in isolated urban forests on the low altitude plain. To clarify future growth of C. japonica in these forests, we investigated their growth, decline levels and water status. The live crown-top heights from the ground (LCTHs) per diameter at breast height (dbh) were lower in forests with C. japonica top dieback than in forests with no top dieback. Furthermore, in a forest with C. japonica top dieback, the LCTHs were similar between trees although dbh and decline levels were different. Moreover, water status near the top of the live foliage was very similar although decline levels were different, suggesting that in urban forests, where C. japonica top dieback is observed, the LCTH is subject of restriction. A sudden increase in temperatures since the 1980s may be restricting the LCTHs of C. japonica in urban forests. We conclude that LCTHs of C. japonica in urban forests are becoming lower and more equal in each forest. If temperature continues to increase, height restriction will become more severe and LCTHs of C. japonica in urban forests will become even lower.     

Comparative phylogeography of four component species of deciduous broad-leaved forests in Japan based on chloroplast DNA variation

A phylogeographic study of four tree species (Padus grayana, Euonymus oxyphyllus, Magnolia hypoleuca, and Carpinus laxiflora) growing in Japanese deciduous broad-leaved forests was conducted based on chloroplast DNA (cpDNA) variations. Using nucleotide sequences of 702–1,059 bp of intergenic spacers of cpDNA, 20, 27, eight, and eight haplotypes were detected among 251, 251, 226, and 262 individuals sampled from 67, 79, 75, and 71 populations of the above species, respectively. The geographical pattern of the cpDNA variations was highly structured in each species, and the following three regional populations were genetically highly differentiated among all four species: (1) the Sea of Japan-side area, (2) the Kanto region, and (3) southwestern Japan. Based on some interspecific similarities among the phylogeographic patterns, the following migration scenario of Japanese deciduous broad-leaved forests was postulated. During the last glacial maximum (LGM), the forests were separately distributed in six regions. After LGM, as the climate warmed, the forests in eastern Japan separately expanded from each of the refugia along the Sea of Japan-side or along the Pacific Ocean-side. In contrast, those in southwestern Japan retreated and moved to high altitudes from each of the continuous forests.     

Growth and annual production of the brown alga Laminaria religiosa introduced into the Uwa Sea in southern Japan

Recently, aquaculture of Laminaria japonica has expanded to the southern coast of Japan and to China along the East China Sea. The southerly distribution of L. religiosa, compared to that of L. japonica, indicated that the aquaculture of L. religiosa along the southern coasts of Japan might be feasible. Thus, we examined the growth, biomass and productivity of L. religiosa cultivated in the Uwa Sea, in southwestern Japan over a period of two years. The seawater temperature ranged from 12.9 to 27.4°C in 2003/2004 and from 12.2 to 28.3°C in 2004/2005. In 2003/2004, the maximum mean density, maximum mean length, and maximum mean wet weight of L. religiosa was 7.8 ± 5.0 ind. m⁻¹ (mean ± SD), 14.8 ± 4.6 cm, and 1.2 ± 0.8 g wet wt., respectively. In 2004/2005, no germination was confirmed through the study period. The maximum biomass and annual production in 2003/2004 were estimated to be 6.9 ± 5.2 g wet wt. m⁻¹ and 8.9 g wet wt. m⁻¹ year⁻¹, respectively. The present study revealed that L. religiosa cultivated in the Uwa Sea were much smaller compared with those of Hokkaido Island, where the alga is naturally found. For the growth of L. religiosa, a relatively long period of seawater temperatures below 13.5°C is required. In the study area, seawater temperatures were below 13.5°C only 11 days in 2003, and 12 days in 2004. As a result, it is thought that expanding the cultivation of L. religiosa to southern areas including the Uwa Sea will be difficult.     

Ausbreitung und beginnende Einbürgerung von Spiraea japonica in ?sterreich

Essl F. 2005. Spread and incipient naturalization of Spiraea japonica in Austria. Bot. Helv. 115: 1–14.The subspontaneous spread and incipient naturalization of the alien Japanese honeysuckle (Spiraea japonica) in Austria were studied by reviewing floristic literature and by surveying a 3-km² area in the alpine foothills of eastern Upper Austria between 1990 and 2004. The literature review shows that the abundance and range of Spiraea japonica have increased in Austria during the 20th century: Until 1945, the species had been recorded in only three mapping units (c. 30 km²) of the floristic mapping project of Austria. Between 1945 and 1990, it was found in seven mapping units, and since 1991, in a total of 20 mapping units. In the field survey, 50 individuals of Spiraea japonica were recorded in 1990, but 198 in 2004. The species mainly occurred in climax forests (Galio sylvatici-Carpinetum) and pioneer forests (Sambucetum racemosae) dominated by Betula pendula; it was less frequent in pine or spruce plantations. No detrimental effects on native plants could be observed. Nevertheless, the further expansion of Spiraea japonica in Central Europe should be monitored attentively as this species is considered invasive in parts of North America.Manuskript angenommen am 13. November 2004     

Intraspecific Genetic Diversity of Undaria pinnatifida in Japan, based on the Mitochondrial cox3 Gene and the ITS1 of nrDNA

The intraspecific genetic diversity of the kelp Undaria pinnatifida (Harvey) Suringar (Laminariales, Phaeophyceae) was investigated using DNA sequences of the mitochondrial cytochrome oxidase subunit 3 (cox3) gene and internal transcribed spacer 1 (ITS1) of nuclear ribosomal DNA in plants collected from 21 localities along the Japanese coast between 2001 and 2003. Morphological variation was also examined and compared with the genetic diversity. Cox3 analyses of 106 plants revealed 9 haplotypes (I–IX) that differed from each other by 1–7 bp (all synonymous substitutions). Haplotype I was distributed in Hokkaido and the northern Pacific coast of Honshu, while haplotype III was found along the Sea of Japan coast of Honshu. Other types were found along the central and southern coast of Honshu. ITS1 analyses of 42 plants revealed 0–1.7% nucleotide differences, but plants from the Sea of Japan coast and northern Japan had similar sequences. The lower genetic differentiation along the Sea of Japan and northern coasts might be due to the recent establishment (after the middle of the last glacial period) of the Sea of Japan flora. The cox3 haplotype of cultivated plants was found in natural populations occurring close to cultivation sites (Naruto, Tokushima Pref., and Hokutan, Hyogo Pref.). This suggests that cultivated plants possibly escaped and spread or crossed with plants of natural populations. Morphological analyses of variation in 10 characters were conducted using 66 plants. The results showed no significant local variation owing to the wide variation in each population and did not support any forma previously described. No correlations between the morphological characters and cox3 haplotypes were detected.     

Population structure of the sailfin sandfish, Arctoscopus japonicus (Trichodontidae), in the Sea of Japan

We analyzed patterns of genetic diversity in the sailfin sandfish (Arctoscopus japonicus), focusing on population subdivisions within the Sea of Japan. We observed 270 specimens from nine sampling sites in 1999–2000, i.e., seven sites in the Sea of Japan and two sites from the Pacific coast of Hokkaido. An additional site (30 specimens) was sampled from eastern Korea in the spawning season of 2004 for comparison. Forty haplotypes, compiled into three haplogroups (A–C), were detected based on the comparison of a 400-bp sequence of the anterior part of the mitochondrial control region. In accordance with previous hypotheses from morphological and molecular analyses, genetic discontinuity between the Sea of Japan and the Pacific coast of Hokkaido was conspicuous. Within the Sea of Japan, eight sampling sites were not genetically uniform, and most of the variations among sites were detected between eastern Korea [the “eastern Korea” (EK) population: distributed from the Korean Peninsula to Mishima, Yamaguchi Prefecture] and the other sites along the coast of Japan [the “western Japan” (WJ) population: from Oki Islands to western Hokkaido] (Φ _CT  = 0.096, P = 0.0183). The WJ population, having lower genetic variability, showed significant departure from neutrality, indicating influences through a recent population expansion. The period of the expansion can be estimated to have begun on the order of 10⁴ years ago. We consider that the present Japan Sea populations have been formed through the invasion of a small ancestral stock to the Sea of Japan and its population expansion during the last glacial period or later. On the other hand, we failed to detect distinct evidence of a population expansion in the EK population. Haplogroup C, detected in a high frequency in this population, was estimated to have mixed with haplogroup A after rapid differentiations of the latter. Therefore, the EK population, strongly influenced by such a mixture, might possess haplogroup C in a higher frequency and a different haplotype composition from the WJ population.     

Parsimony analysis of the distribution pattern of Japanese primary freshwater fishes, and its application to the distribution of the bagrid catfishes

The geographic distribution of Japanese primary and some secondary freshwater fishes was analyzed using parsimony analysis of endemicity (PAE). Analysis of 73 taxa (species and intraspecific forms) on the four main islands of Japan (divided into 25 geographic areas), produced 44 most parsimonious cladograms. In all of the latter, a total of eight single and compound areas were recognized as endemic areas in nested relationships. The area cladograms showed Japan as comprising a middle-eastern Hokkaido area plus southern areas, the latter containing mainly a northeastern-Honshu endemic area and more heterogeneous southwestern areas, including four endemic areas (western Kyushu, southeastern Chugoku, middle Kinki and Tokai around Ise Bay) and several peripheral areas. Some patterns, e.g., the distinction in fauna across Fossa Magna, noted by previous studies, were supported by these results. Even though the analysis had some problems (e.g., not all geographic ranges of taxa could be included), it provided evidence for the detection of general distribution patterns, because the relationships or similarities among areas were clearly defined by shared taxa. To demonstrate the historical implications of the analysis, the allopatric distribution of, four bagrid catfishes was reconsidered in the area cladogram. The general pattern implied secondary extinction ofPseudobagrus nudiceps around lse Bay, which was in keeping with the fossil record.     

Reciprocal distribution of two congeneric trees, Betula platyphylla var. japonica and Betula maximowicziana, in a landscape dominated by anthropogenic disturbances in northeastern Japan

Aim Information has been compiled on disturbance regimes and the life‐history characteristics of Betula platyphylla var. japonica (Miq.) Hara and B. maximowicziana Regel to investigate the impact of humans on the present distribution patterns of these two congeneric tree species. Location The study area is in the central region of the northern Kitakami Mountain Range, located in the northeast of Honshu Island, Japan. Methods First, the present distributions of B. maximowicziana and B. platyphylla var. japonica were mapped at the landscape scale. To examine the factors affecting the distribution patterns, topographic features and past land use were taken into account. Second, life‐history traits of both species were clarified at various growth stages either by fieldwork or through a literature search. Previous studies have provided some information on seed production, seed dispersal, seedling dynamics, sprouting, and growth. In the present study, field observations and experiments were conducted regarding seed‐bank formation, size and age at reproduction, and the life span of canopy trees. Results Betula platyphylla var. japonica and B. maximowicziana were spatially segregated in the studied landscape (14,000 ha). The distribution of each species was correlated more strongly with land use at the beginning of the twentieth century than with site environmental factors such as altitude or slope angle. Betula platyphylla var. japonica was distributed more frequently on former grasslands, whereas B. maximowicziana was almost exclusively limited to past old‐growth forests. As typical pioneers, the two species showed similar life‐history traits but differed in several critical points. Betula platyphylla var. japonica has a vigorous sprouting ability, which might increase its resistance to burning and logging, whereas B. maximowicziana forms a persistent seed bank in the soil, indicating an advantage in regenerating in disturbances found in forest communities. Other critical differences were detected in age‐related characteristics such as minimum age of reproduction and life span. Main conclusions The earlier reproductive maturity and the shorter life span of B. platyphylla var. japonica indicate a shorter population cycle than that for B. maximowicziana. The latter would be excluded from grasslands that were burned frequently, as a result of the longer time span before initial reproduction and its poor sprouting ability. In contrast, B. platyphylla var. japonica would be excluded from old‐growth forests, where disturbance was infrequent, owing to its shorter life span and lack of a persistent seed bank.