Structure and regeneration of canopy species in an old-growth evergreen broad-leaved forest in Aya district,southwestern Japan

The population structure and regeneration of canopy species were studied in a 4 ha plot in an old-growth evergreen broad-leaved forest in the Aya district of southwestern Japan. The 200 m × 200 m plot contained 50 tree species, including 22 canopy species, 3,904 trees (dbh5 cm) and a total basal area of 48.3 m²/ha. Forty one gaps occurred within the plot, and both the average gap size (67.3 m²) and the total area of gap to plot area (6.9%) were small. Species found in the canopy in the plot were divided into three groups (A, B, C) based on size and spatial distribution patterns, and density in each tree size. Group A (typical species: Distylium racemosum, Persea japonica) showed a high density, nearly random distribution and an inverse J-shaped size distribution. Species in group B (Quercus salicina, Quercus acuta, Quercus gilva) were distributed contagiously with conspicuous concentration of small trees (<5 cm dbh) around gaps. However, the species in this group included few trees likely to reach the canopy in the near future. Group C included fast-growing pioneer and shade intolerant species (e.g. Cornus controversa, Carpinus tschonoskii, Fagara ailanthoides), which formed large clumps. Most gaps were not characterized by successful regeneration of group B and C but did appear to accelerate the growth of group A. Group B species appear to require long-lived or large gaps while group C species require large, catastrophic disturbances, such as landslides, for regeneration.     

Differences in sapling architecture betweenFagus crenata andFagus japonica

The ecological significance of architectural patterns for saplings ofFagus crenata andFagus japonica co-occurring in a secondary oak forest were evaluated by comparing the size and shape of leaves, trunks and crowns.Fagus japonica saplings were different fromF. crenata saplings in some architectural properties: (i) the leaf area and specific leaf area were larger; (ii) the ratio of sapling height to trunk length was lower, indicating greater leaning of the trunk; and (iii) the projection area of the crown was larger and the leaf area index lower indicating less mutual shading of leaves. These architectural features indicated thatF. japonica saplings were more shade tolerant thanF. crenata andF. crenata saplings were superior toF. japonica for growth in height and could, therefore, utilize sunlight in the upper layer. An erect trunk inF. crenata and a leaning trunk inF. japonica may be important characteristics associated with the regenerations patterns of each species; regeneration from seedlings under canopy gaps in the former and vegetative regeneration by sprouting in the latter.     

Development and polymorphism of microsatellite markers for Fagus crenata and the closely related species, F. japonica

 We have developed microsatellite markers (SSRs) applicable to Fagus crenata using the RAHM method and investigated their polymorphisms. We also applied the SSRs in an analysis of a closely related species, F. japonica. Here we describe the isolation and characterization of nine polymorphic microsatellite markers, of which eight are applicable to both species. Among 30 individuals of each of F. crenata and F. japonica we detected a total of 79 and 77 alleles, respectively, with an average of 9.9 and 8.6 alleles per locus. The mean expected heterozygosity (He) was 0.615 (range: 0.216–0.925) in F. crenata and 0.660 in F. japonica (range: 0.259–0.827). The He values were considerably higher than those previously found for isozymes. Paternity exclusion probabilities for multiple loci, calculated over all loci, were extremely high (0.999 and 0.998 in F. crenata and F. japonica, respectively): sufficiently high to study pollen flow in both species. Received: 5 December 1998 / Accepted: 28 December 1998     

Mycena auricoma,a new species ofMycena sectionRadiatae from Japan,andMycena spinosissima,a new record in Japan

Two lignicolous species ofMycena (Agaricales, Basidiomycetes) are described and illustrated from eastern, Japan:Mycena auricoma sp. nov., forming ephemeral coprinoid basidiomata and belonging to sectionRadiatae, was found on a dead fallen twig ofQuercus serrata. It appears to close to a Malaysian species,“Trogia” crinipelliformis. Mycena spinosissima in sectionSacchariferae, new to Japan, was collected from dead bark ofAphananthe aspera, a dead fallen inflorescence ofCryptomeria japonica, and a dead fallen twig ofQuercus serrata.     

Mitochondrial DNA Variation Follows a Geographic Pattern in Japanese Beech Species

The amount and distribution of mitochondrial (mt) DNA restriction fragment length polymorphism was determined among individual tree samples of two Japanese beech species, Fagus crenata and F.japonica. Individual plants were collected from 16 F. crenata populations throughout the range of the species, and from three F. japonica populations. We detected enough variation to characterize eleven and three chondriome types in F. crenata and F.japonica, respectively. The grouping of beech chondriome types based upon the cladistic analysis of mtDNA polymorphism allowed us to recognize the apparent geographical patterns of mtDIMA diversity: the resulting three main groups occupied distinct geographic areas. This geographic differentiation is likely to reflect the history of the Japanese beech forests after the last glacial period of the Pleistocene. In addition, the mtDNA polymorphism encountered within F. crenata encompassed all the variation observed in F.japonica. Our result suggests the need for re-evaluation of their phylogenetic relationships.     

Gap dynamics in climaxFagus crenata forests

Gap characteristics and gap regeneration were studied in several climaxFagus crenata forests in Japan. 278 gaps were observed. Gaps covered 12% of the total land area of 20.05 ha. Gap density was 13.9 gaps per ha and, mean gap size was 92.0 m². Smaller gaps were much more frequent than larger ones. Gaps larger than 400 m² were rare. Most gaps were created by the death of single trees. Canopy trees died more often standing or with broken trunks than by uprooting, although uprooted trees were relatively abundant in the site with poor soil drainage and in the site on upper slope. Differences of gap regeneration behaviour were recognized among tree species.F. crenata regenerates in gaps from saplings recruited before gap creation and can replace not only its own gaps but also gaps of other species. Most species other thanF. crenata andMagnolia obovata could not regenerate in their own gaps. More successful regeneration ofF. crenata may occur in gaps smaller than 200 m², althought it regenerated in a wide range of gap size. However, increased relative density ofF. crenata in the canopy layer seems to prevent its successful regeneration. Gap regeneration of other species did not clearly depend on a species-specific gap size.     

Platypus quercivorus ambrosia beetles use leaf volatiles in host selection

Although chemical volatiles emitted from host and non-host trees have been suggested as important cues for bark and ambrosia beetles, their responses to leaf volatiles is poorly understood. The oak ambrosia beetle, Platypus quercivorus (Murayama) (Coleoptera: Curculionidae), is a vector for the fungus that causes Japanese oak wilt. Using a Y-tube olfactometer, we tested the behavioral response of P. quercivorus to leaf volatiles emitted from four host trees – Quercus crispula Blume, Quercus serrata Murray, Quercus salicina Blume, and Castanea crenata Sieb. & Zucc. (all Fagaceae) – and two non-host trees, Fagus crenata Blume (Fagaceae) and Cryptomeria japonica D. Don (Cupressaceae). A flight mill was used to evaluate the effect of flight on the behavioral response to leaf volatiles. The bioassays were repeated 10× before and 10× after flight in the flight mill for each of the 54 individual beetles. Leaf volatile components were analyzed using gas chromatography–mass spectrometry. The bioassay results supported our hypothesis: P. quercivorus was attracted by the leaf volatiles of hosts and was deterred by the leaf volatiles of non-hosts. The behavioral response of P. quercivorus to the leaf volatiles was stronger after flight. Males had a stronger behavioral response than females to leaf volatiles. The leaf volatile chemical profile of the non-host C. japonica differed from the profile of the host plants. However, the chemical profile of the non-host F. crenata was similar to the profile of the hosts. Our findings provide insight into the functions of leaf chemical volatiles in the interaction of P. quercivorus with its hosts and non-hosts and may help improve the control of P. quercivorus and Japanese oak wilt.     

Shoot structure and dynamics of saplings and canopies of three deciduous broad-leaved trees of a coppice forest in central Japan

Three deciduous broad-leaved trees, Quercus serrata, Castanea crenata and Carpinus laxiflora, were the main constituents of a coppice forest in central Japan. The shoot elongation and leaf emergence modes of both saplings and the canopy of the three species were investigated. The shoot elongation modes of Q. serrata and C. crenata were the same in saplings and the upper layer of the canopy. The second shoots of these two species were formed after the first shoots were elongated. C. laxiflora was different between saplings and the upper layer of the canopy. In saplings, only the first shoots took a long time to elongate. In the upper canopy layer, higher order shoots were formed in the same way as in the other two species. In the lower layer of the canopy, all three species showed the same shoot elongation mode, in which only the first shoot and its duration of elongation was short. Leaf longevity, individual leaf area, leaf mass per unit leaf area and the stem mass per unit stem length of C. laxiflora were significantly shorter or significantly smaller than those of Q. serrata and C. crenata. The length of the stem per unit leaf area of C. laxiflora was three times that of Q. serrata and five times that of C. crenata. The elongation growth of C. laxiflora was highly efficient as it occurred with a small leaf area. The shoot dynamics and the shoot structure of C. laxiflora are more suitable for elongation growth than in Q. serrata and C. crenata. Furthermore, the shoot structures of the three species were compared and ecological characteristics of the three species are discussed. Received: 29 September 1998 / Accepted: 17 September 1999     

Early seedling growth of pine (Pinus densiflora) and oaks (Quercus serrata,Q. mongolica,Q. variabilis) in response to light intensity and soil moisture

In climatic chambers seed germination and seedling growth of Pinus densiflora Sieb. et Zucc., Quercus serrata Thunb., Quercus mongolica Fisch. ex Turcz. and Quercus variablilis Bl. were investigated as functions of light intensity and soil moisture. In Korea these tree species occur widely and form mixed forests with different distributions. Species clearly differed in the pattern of germination and early seedling growth between light and soil treatments. The germination of pine did not differ between the experimental treatments until the breaking of the primary buds. After that, light intensity was the deciding factor for further development. In the most moist treatment (approx. field capacity) growth of the pine seedlings was strongly inhibited. For the three oak species, differences between experimental treatments first occurred after complete formation of primary leaves. Seed development strongly correlated with the weight of the acorn. The large seeded Q. variabilis (acorns with mean weight of 4.7 g) developed faster and reached larger dimensions towards the end of the experiment than Q. mongolica (2.8 g per acorn) and Q. serrata (0.9 g per acorn). Regarding height and biomass growth, the oak species showed a higher shade tolerance than pine. The proleptic shoot growth was clearly influenced by the light intensity. Root formation was favoured by a high exposure to light. In case of the oak species reduction of soil moisture increased the length of primary roots and the number of secondary roots.     

Dynamics and conservation of the gwangneung national forest in central Korea: A national model for forest restoration

Forests in Gwangneung National Arboretum District (GNAD) have been protected since the 15^th century. Consequently, these forests support more than 20% of all plant species in Korea. We constructed vegetation maps for landscape analysis, and forest dynamics, species diversity, and sustainable management were discussed. Secondary forests compose 51.0% of the whole vegetation, while plantations compose 45.2%.Quercus serrata dominates the forest, and the plantations are comprised mainly ofPinus koraiensis. Although dominated by plantations and human installations, the presence of a rare riparian hardwood forest, composed primarily of Q.aliena, was notable. Species diversity of the riparian (H′ = 3.38) was significantly (p<0.0001) higher than the upland (H′ = 1.56). Species turnover rate as a spatial heterogeneity was also higher. Such high species diversity and heterogeneity are justification to conserve the riparian and lowland forests in GNAD. Extensive recruitments of their own seedlings and saplings suggest a sustainable regeneration of Q.serrata and Q.aliena stands in the lower elevations, and the opposite is true for the Q.mongolica andP. rigida stands in higher elevations. GNAD contains diverse natural landscape elements that range from riparian to upland vegetation, which may well serve as a national model for forest restoration.     

Regeneration dynamics, causal factors, and characteristics of pacific ocean-type beech (Fagus crenata) forests in Japan: A review

This paper reviews the differences in the distribution and regeneration ofFagus crenata between two types of Japanese beech forests, the Japan Sea (JS)-type and the Pacific Ocean (PO)-type, and discusses the causal factors and characteristics of these forests, particularly the PO-type.F. crenata in PO-type forests regenerates sporadically rather than constantly, whereas regeneration in the JS-type forests is relatively constant with gap dynamics.F. crenata has dominated in snowy areas both in the past, after the last glacial age, when there was less human disturbance, and in the present. Snow accumulation facilitates beech regeneration in snowy JS-type forests, but not in the less snowy PO-type. Snow protects beechnuts from damage caused by rodents, desiccation, and freezing. In addition, snow suppresses dwarf bamboo in the spring, thus increasing the amount of sunlight available for beech seedlings on the forest floor. Snow also supplies melt water during the growing season and limits the distribution of herbivores. Moreover, snow reduces the number of forest fires during the dry winter and early spring seasons. The low densities ofF. crenata impede its regeneration, because disturbed wind pollination lowers seed fertility and predators are less effectively satiated. In snowy JS-type beech forests,F. crenata dominates both at the adult and the juvenile stages because it regenerates well, while other species are eliminated by heavy snow pressure. On the less snowy PO-side, deciduous broad-leaved forests with various species are a primary feature, althoughF. crenata dominates because of its large size and long lifespan.     

Roles of riparian and secondary forests in maintaining the near-threatened butterfly, Sasakia charonda (Lepidoptera, Nymphalidae), populations in Japan

To clarify the habitat requirements of the near-threatened butterfly, Sasakia charonda (Lepidoptera, Nymphalidae), we studied the distribution pattern of its host trees, Celtis sinensis and Celtis jessoensis, and the utilization patterns of various vegetation types by this butterfly in the Oofukasawa River basin in Hokuto City, Yamanashi Prefecture, central Japan. Two species of host trees, C. sinensis and C. jessoensis (height = 2 m or more) were found in riparian forests on sandbanks (hereinafter, riparian forest), in forest regenerated after landslides on valley walls (landslide tracks), in secondary deciduous forests consisting mainly of Quercus acutissima or Quercus serrata and in forests established at abandoned paddy fields and their periphery, where weeds and shrubs used to be mown frequently to avoid shade on the paddies before their abandonment. This suggests that they are pioneer species, and their distribution and regeneration depend on natural and/or human disturbances. Host trees above 2 m were preferred by larvae, and there were very few such trees in secondary forests. More overwintering larvae occurred in riparian forests than at other sites. The number of S. charonda adults was highest at the edge of riparian forests, and we observed a variety of behaviors such as puddling, chasing and mating there. Although the number of adult butterflies was smaller inside and at the edge of secondary forests than in riparian forests, puddling by males and roosting on the trunk of Q. acutissima or Q. serrata by females were observed more frequently there than in riparian forests. Thus, we conclude that landscapes including both riparian forests with natural disturbance and secondary forests with Quercus trees are necessary to maintain host Celtis trees and S. charonda populations.     

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.     

The regeneration process in a mixed forest in central Hokkaido,Japan

The regeneration process in a mixed forest was investigated in Nopporo National Forest, Hokkaido. The analysis of age structure in an 80 m×80 m plot revealed that almost all of the species regenerated intermittently. In eleven gaps observed in the plot, the regeneration of a boreal conifer (Abies sachalinensis) was seldom observed. Temperate hardwoods, even climax species (Acer mono, Quercus mongolica var. grosseserrata, Tilia japonica), regenerated vigorously in the gaps. The age structure in ten additional plots scattered all over the forest showed that Abies tended to regenerate synchronously. From previous records, regeneration of Abies could be ascribed to catastrophic storms causing serious windfalls. On the other hand, regeneration of the temperate hardwoods was not synchronous but independent in different places within the forest. They could regenerate not only after those catastrophic storms but also after less severe disturbances which caused the death and fall of one or several trees. It is concluded that the coexistence of boreal coniferous species and temperate deciduous broad-leaved species in mixed forests may be maintained not only by the difference in habitat but also by the balance between the less frequent large disturbances, and the more frequent smaller ones.     

Suppression and release during canopy recruitment in Fagus crenata and Acer mono in two old-growth beech forests in Japan

Beech forests occur widely in the mountains on the main island of Japan. Wind storm is the major regime that causes canopy disturbances in these forests. Fagus crenata Blume is a dominant, and Acer mono Maxim., also a canopy species, co-occurs in these forests. It has been suggested that A. mono is less shade-tolerant than F. crenata. Using dendrochronological data, this study describes suppression and release histories during canopy recruitment for these two species in two old-growth beech forests (at Takahara and Kaname) and provides support for the shade tolerance suggestion given above. In addition, disturbance histories over the past 130 or 160 yr in the two forests have been reconstructed. At Takahara, the forest experienced more frequent wind storms, was about 10–15 m shorter and less dense than that at Kaname. Kaname is in a heavy snow region. On average, F. crenata experienced 1.4 and 2.5 definable episodes of suppression during canopy recruitment at Takahara and Kaname, respectively. At Kaname, the average length of total suppression was 66 yr, and 34 yr at Takahara. On average, at final release, the beech trees had a diameter of 25 cm and an age of about 125 yr old, which were twice as large and twice as old as those at Takahara. In contrast, at the two sites, A. mono experienced similar average numbers of episodes (1.6 episodes at Takahara and 1.8 episodes at Kaname) and similar average length of total suppression (37 yr at Takahara and 30 yr at Kaname) during canopy recruitment. At both sites, at final release, the maple had an average diameter of about 18 cm and an average age of some 70 yr. Our results have revealed that F. crenata is able to be tolerant of a longer shade suppression than A. mono. At Kaname, the canopy disturbances deduced from tree-ring data were more intense or frequent than those at Takahara, This contrasted with occurrences of wind storms at the two sites.     

Analysis of the multi-stem clump structure ofLitsea japonica Juss. growing in a coastal dwarf forest

The multi-stem clump structure of a coastal dwarf forest dominated byLitsea japonica Juss. was investigated in order to clarify the sprouting characteristics and self-maintenance of clumps by stem alternation. The size and age distribution of multi-stem clumps were analyzed using cumulative relative frequency curves.L. japonica had a large number of stems and an even height distribution or young age-biased distribution of stems within a clump. These results indicated the sequential flushing of sprouts at high frequency. Height distribution within a clump ofL. japonica was relatively even compared to other species. This clump structure suggested the stable self-maintenance of individuals in all ranges of size and age without disturbances. It originated specific sprouting characteristics as a response to the severe stress of salty wind.Ardisia sieboldii Miq. had few stems within a clump. Although the stem height distribution of large individuals tended to be even, most clumps had a large size-biased distribution of stem height which indicated simultaneous sprouting. From this structure, sprouts of this species were thought to be of less significance in the stable self-maintenance of individuals thanL. Japonica.     

Differences in beech (Fagus crenata) regeneration between two types of Japanese beech forest and along a snow gradient

Differences in beech (Fagus crenata) regeneration were quantitatively investigated using power function analysis for the size–class (diameter at breast height, DBH) distribution and juvenile-to-canopy tree (J/C) ratio along a snow gradient throughout Japan. In snowy areas, all species combined, as well as F. crenata alone, showed constant regeneration, with parameter b≈−1.6 for the power function y=ax ^b (x=DBH, y=density), which is related to the DBH–class distribution. The good fit of the data to the function suggests that beech regenerates constantly with self-thinning patch dynamics. Parameter a, which indicates the abundance of small trunks, was high. Furthermore, the mean J/C ratio was ≈8, i.e., each parent beech tree produced eight juveniles. These results suggest that beech regenerates constantly with gap dynamics in snowy beech forests on the Japan Sea side of Japan (snowy). However, the fit of F. crenata was lower and nonsignificant in some forests in less snowy areas, despite the high fit of all species combined. In these areas, the mean of a was low, and b was often near zero for F. crenata regressions. These results suggest that the abundance of beech was low, and self-thinning was not evident because of the initial low abundance. Moreover, the mean J/C ratio was <1.0, suggesting that juvenile density was lower than that of canopy trees. Thus, the regeneration of F. crenata on the Pacific Ocean side of Japan (less snowy) is rather sporadic. Less snowy conditions may promote seed desiccation, predation of beechnuts and seedlings, and water stress. Lower F. crenata density may also reduce predator satiation and wind pollination.     

Changes in woody vegetation abundance and diversity after natural disturbances causing different levels of mortality

Questions: How does woody vegetation abundance and diversity differ after natural disturbances causing different levels of mortality? Location: Abies balsamea–Betula papyrifera boreal mixed‐wood stands of southeast Quebec, Canada. Methods: Woody vegetation abundance and diversity were quantified and compared among three disturbance‐caused mortality classes, canopy gap, moderate‐severity disturbances, and catastrophic fire, using redundancy analysis, a constrained linear ordination technique, and diversity indices. Results: Substantial changes in canopy tree species abundance and diversity only occurred after catastrophic fire. Shade‐tolerant, late‐successional conifer species remained dominant after canopy gap and moderate‐severity disturbances, whereas shade‐intolerant, early‐successional colonizers dominated canopy tree regeneration after catastrophic fire. Density and diversity of mid‐tolerant and shade‐intolerant understory tree and shrub species increased as the impact of disturbance increased. Highest species richness estimates were observed after catastrophic fire, with several species establishing exclusively under these conditions. Relative abundance of canopy tree regeneration was most similar after canopy gap and moderate‐severity disturbances. For the sub‐canopy tree and shrub community, relative species abundances were most similar after moderate‐severity disturbances and catastrophic fire. Vegetation responses to moderate‐severity disturbances thus had commonalities with both extremes of the disturbance‐caused mortality gradient, but for different regeneration layers. Conclusions: Current spatio‐temporal parameters of natural disturbances causing varying degrees of mortality promote the development of a complex, multi‐cohort forest condition throughout the landscape. The projected increase in time intervals between catastrophic fires may lead to reduced diversity within the system.     

Gap regeneration of major tree species in different forest types of Japan

Gap regeneration of major tree species was examined, based on the pattern of gap phase replacement, in primary old-growth stands of warm-temperate, cool-temperate and subalpine forests, Japan. Using principal component analysis, the gap-regeneration behavior of major tree species could be divided into three guilds and that of Fagus crenata (monodominant species of cool-temperate forests). The criteria used for this division were total abundance of canopy trees and regenerations and relative abundance of regenerations to canopy trees. The gap-regeneration behavior of species in the first guild was that canopy trees regenerate in gaps from seedlings or saplings recruited before gap formation; they had higher total abundance and more abundant regenerations relative to their canopy trees. The gap-regeneration behavior of F. crenata was same as species in the first guild, but F. crenata had less abundant regenerations relative to its canopy trees. Species in the second guild had lower total abundance and less abundant regenerations to their canopy trees. The guild contained species whose canopy trees regenerate in gaps from seedlings or saplings recruited after gap formation or regenerate following largescale disturbance. The third guild consisted of species with lower total aboundance and more abundant regenerations relative to their canopy trees. The gap-regeneration behavior of some species in this guild was that trees regenerate in gaps from seedlings or saplings recruited before gap formation, and grow, mature, and die without reaching the canopy layer, while the gap-regeneration behavior of other species was same as that of species in the first guild or F. crenata. Major tree species of subalpine forests were not present in the third guild.