Dwarf Bamboo Research Articles

The effect of shelterwood logging on the diversity of plant species in a beech (Fagus crenata) forest in Japan

To clarify the effect of shelterwood logging on the diversity of plant species in a beech (Fagus crenata) forest in central Japan, we compared the species composition and the organization of vascular plant communities in stands that were managed 10 years ago with those in primary stands. There were no significant differences between the stands in the species diversity (H′, J′, and number of species) of either forest floor plants or tree species. The species diversity of forest floor plants was significantly positively correlated with stand structure parameters (number of stems and number of stems per individual, and frequency of occurrence of dwarf bamboo) that increased in value after logging. However, the number and the frequency of occurrence of species that occurred disproportionately in primary stands were significantly negatively correlated with the same parameters. Shelterwood logging has been reported to make effective beech regeneration more difficult in many Japanese beech forests, including this forest, but this method might not significantly affect plant species diversity.

Structure, dynamics and disturbance regime of temperate broad‐leaved forests in Japan

Abstract. Structure, diversity and dynamics of five Japanese temperate old‐growth forests were compared, differing from each other in, i.a., climate, dominant tree type, topography, disturbance regime. The forests were Aya, Ogawa, Kanumazawa Riparian, Kanumazawa upland and Senju. A permanent plot (1–6 ha) was established in each forest and trees were censused several times at intervals of two years. Mean annual recruitment rates and mortality rates in these forests were both in the range of 0.5 to 4.6 %/yr at the community level. Analyses of the structure and dynamics of populations showed that the underlying process was different among the forests. Some forests experienced compositional shifts in their canopies, others had a constant canopy composition but appeared to lack effective regeneration in recent years. The recruitment rate appeared to be strongly affected by competitive undergrowth vegetation such as dwarf bamboo which has been controlled by natural disturbance or human impact. It is likely that the forests with mostly low recruitment rates had a low species diversity. The current variation in structure, diversity and dynamics of the studied forests might have been determined not only by physical conditions (e.g. climate) but also by chance factors (e.g. disturbance, outbreak of deer population).

Long‐term growth dynamics of natural forests in Hokkaido, northern Japan

Abstract. The long‐term growth dynamics of natural forest stands on the island of Hokkaido were described on the basis of an analysis of data from 38 permanent plots spanning 15–22 yr. Stand structure was characterized by basal area, stem density and tree size variability. To detect trends in stand structure, regression models for recruitment rate (per ha per yr), mortality rate and the rate of change in stem density and tree size variability were developed by a stepwise method using initial basal area, stem density, tree size variability, species composition summarized by LNMDS ordination, altitude, annual mean temperature, annual precipitation, type of understorey vegetation, topography and slope aspect as candidates for predictor variables. The same analyses were conducted for basal area increment (net growth) and its components: survivor growth = basal area gain by growth of surviving individuals and mortality = basal area loss by death of individuals.Stem density remained generally unchanged; recruitment was relatively low even in very sparse stands. Stand basal area generally increased as survivor growth was approximately double the mortality.Recruitment rate was strongly affected by the presence of dwarf bamboo (Sasa spp.) vegetation on the forest floor which inhibited tree regeneration. Mortality rate was density‐dependent; dense stands had higher mortality than sparse stands. Density change rate (recruitment rate ‐ mortality rate) was, therefore, determined by both the type of understorey vegetation and stem density. Survivor growth was high in stands with high stem density and basal area. Mortality was dependent on basal area and altitude. Net basal area increment (net growth) was dependent only on stem density with other factors that influenced survivor growth and mortality omitted. Tree size variability decreased in stands with high tree size variability whereas it increased in stands with low size variability. Based on the obtained models for density change rate and net basal area increment, trajectories of stands were illustrated on a log‐log diagram of stem density and basal area. The predicted differences in trajectories as affected by the understorey vegetation type indicated the importance of dwarf bamboo vegetation for forest dynamics on Hokkaido.

Size‐structure dynamics of two conifers in relation to understorey dwarf bamboo: A simulation study

Abstract. Size‐structure dynamics and co‐existence of the conifers Abies sachalinensis and Picea glehnii in subalpine forests in Japan, in relation to the understorey dwarf bamboo Sasa, were examined using a simulation model. This model explicitly incorporated recruitment rate, size growth rate and mortality. Recruitment and growth rates were assumed to be suppressed by the cumulative basal area of taller trees and the density of Sasa. As for the one‐sided crowding effect, two types of model were examined. The total basal area of the two species suppresses the growth and recruitment rates in an additive model, while the basal area of each species has a separate effect included in a specific model. Two types of recruitment process were examined, i.e. open and closed systems; recruitment rates of open and closed systems are independent of, and proportional to, the basal area of the same species within the plot, respectively. Parameters were estimated from data of plot censuses for four years. The parameters of the specific model showed that recruitment and size growth rates were more suppressed by the same species than the other species. Recruitment of A. sachalinensis was more sensitive to suppression by Sasa compared with P. glehnii. The stationary size structure of the two species, generated from both the models with the open system, fitted well to the observed size structures across various Sasa densities. A. sachalinensis and P. glehnii dominated at lower and higher densities of Sasa, respectively. However, the closed‐system simulation showed that the stable co‐existence of the two species with a good fit to the observed size structure occurred only in the specific model.These results suggest that within‐species interference, which is more severe than between‐species interference, is important for the co‐existence of the two species and that the relative dominance of the two species readily explained the differential responses to Sasa abundance.

The Effects of Selective Logging on Stand Structure and the Regeneration of Subboreal Forests in Hokkaido, Northern Japan

We investigated the effects of selective logging on stand structure and regeneration in selectively logged subboreal forests in Taisetsuzan National Park in Hokkaido in northern Japan. The basal area decreased and the size structure of trees altered in the stands studied due to repeated, intense selective logging, in which larger trees were cut down as a priority. Sapling density in the stands was much lower than that in primary forests. In the simple and multiple regression analyses that were used to estimate the effects of selective logging on sapling density, sapling density had a significant positive correlation with tree density and had little correlation with the density of logged stumps or the height ofSasa (dwarf bamboo) growing on the forest floor. These results suggest that the establishment sites around canopy trees influenced the establishment of saplings, rather than the gaps caused by selective logging. However, both the coefficient of determination and the standardized partial regression coefficient of multiple regression analysis were higher for the stand with a dense cover ofSasa than for the stand with a sparse cover ofSasa. Thus, the success of regenerating forests with selective logging depends on both the site of advanced regeneration and the light conditions that regulate growth.

北海道石狩川下流域におけるチュウヒＣｉｒｃｕｓ ｓｐｉｌｏｎｏｔｕｓ ｓｐｉｌｏｎｏｔｕｓの繁殖状況

Breeding of the Eastern Marsh Harrier (Circus spilonotus spilonotus Kaup 1847) was confirmed in the area along the Ishikari River in the Ishikari District, Hokkaido, Japan. Among the eight nests discovered during the 1988 breeding season, eggs were observed in three nests, and chick (s) were confirmed in three other nests. The remaining two nests had no eggs or chicks. One might have been examined before eggs were laid, and the other might have been abandoned. In addition, two other sites were considered to be probable breeding sites, though the nests could not be found. Breeding processes were not pursued because the confirmation of breeding was the main purpose of this investigation. It was noteworthy that two nests had been built of bamboo grasses on the ground amongst dwarf bamboo. The other six nests were built of reeds in reed marshes as is generally known.

Significance of aspect and understory type to leaf litter redistribution in a temperate hardwood forest

Annual production and redistribution of leaf litter were compared among three distinct understory patches in a temperate hardwood forest dominated by Quercus mongolica, Kalopanax pictus, Acer pseudo‐sieboldianum, and Carpinus cordata. Two patches were located on a southwest‐facing slope: one with an understory dominated by herbaceous plants (Patch S), and the other covered with evergreen dwarf bamboo, Sasa borealis (Patch SS). The third patch was on the opposite slope with an understory dominated by herbaceous plants (Patch N). Annual leaf litterfall was averaged 330 gm‐2 yr‐1 in the three patches from 1994 to 1998. From mid‐September 1996 to mid‐September 1997, net transport of leaf litter over patch boundaries was 1,824 g m‐1 from Patch S to SS, 1,465 g m‐1 from Patch S to N, and 886 g m‐1 from Patch SS to N. The amounts moving downslope out of Patch S, SS, and N were 2,548, 471, and 588gm‐1, respectively. When a mass balance approach was employed for the data of leaf litter transport, the results were ...

Effects of bark-stripping by Sika deer ( Cervus nippon) on population dynamics of a mixed forest in Japan

The effects of tree bark-stripping by Sika deer ( Cervus nippon) on population dynamics of forest trees were studied in a cool-temperate mixed forest in Ohdaigahara, western Japan. Detailed observation of all trees ≥2 cm in diameter at breast height in a 1 ha plot for 2 years showed that stems of Abies homolepis, Clethra barvinervis, Viburnum furcatum, Stewartia pseudo-camellia and Ilex geniculata suffered serious bark-stripping by deer. Smaller stems of A. homolepis were girdled all at once, and dead soon after that. Larger stems were bark-stripped little by little, and did not die unless completely girdled. Stems of C. barvinervis and S. pseudo-camellia did not die soon after bark-stripping even if completely bark-stripped. The tree population monitored in two 0.2 ha belt transects for 15 years demonstrated that the mortality of A. homolepis and V. furcatum has increased consistently, especially in the last 5 years. In contrast, no tendencies were found for Fagus crenata, Pourthiaea villosa and Symplocos coreana; these species were seldom bark-stripped by deer. Recruitment rate in the whole forest decreased in recent years. Thus the density of smaller trees decreased due to high mortality of bark-stripped species and low recruitment rate for all species. Though the bark of trees is less important as forage for deer than green forage such as dwarf bamboo, bark-stripping does more serious damage to trees than browsing on leaves and twigs because the injury by bark-stripping does not readily recover and kills considerably large trees. The ratio of canopy gap will be increased by browsing unless the density of deer is reduced. Furthermore, bark-stripping accelerates the increase of canopy gap ratio.

Population Biology of Grasses

Contributors Preface Darwin revisited: approaches to the ecological study of grasses A. D. Bradshaw Part I. Population Variation and Life History Patterns: 1. Allozyme diversity in the grasses M. J. W. Godt and J. L. Hamrick 2. Ecology of seed dormancy and germination in grasses C. C. Baskin and J. M. Baskin 3. Seed dispersal and seedling establishment in grass populations G. P. Cheplick 4. Clonal biology of caespitose grasses D. D. Briske and J. D. Derner 5. Ecological aspects of sex expression in grasses J. A. Quinn 6. Interspecific variation in plasticity of grasses in response to nitrogen supply E. Garnier 7. Population biology of intraspecific polyploidy in grasses K. H. Keeler Part II. Ecological Interactions 8. Plant-plant interactions in grasses and grasslands W. K. Lauenroth and M. O. Aguilera 9. Competition between grasses and woody plants S. D. Wilson 10. Fungal endophyte infection and the population dynamics of grasses K. Clay 11. Arbuscular mycorrhizas and the population biology of grasses K. K. Newsham and A. R. Watkinson Part III. Population Biology of Specific Groups: 12. Population dynamics in the regeneration process of monocarpic dwarf bamboos, Sasa species A. Makita 13. Population dynamics of perennial grasses in African savanna and grassland T. G. O'Connor and T. M. Everson 14. A life cycle approach to the population ecology of two tropical grasses in Queensland, Australia D. M. Orr Index.

Functional Leaf Phenotypes for Shaded and Open Environments of a Dominant Dwarf Bamboo (Sasa senanensis) in Northern Japan

Dense patches of evergreen dwarf bamboo species (1-3 m), such as Sasa senanensis, often prevent forest tree regeneration, and they suppress competing grassland species in Japan. We hypothesized that its evergreen habit contributes to the dominance of S. senanensis through carbon gain during the phenological gaps of spring and late fall under the improved irradiance and moisture conditions in a deciduous forest. We monitored the seasonal patterns of gas exchange in S. senanensis growing in the forest understory and in the open. The timing of greatest carbon gain in shade leaves was during early spring and late fall under a leafless forest canopy compared with that of late spring and early summer for open-grown leaves. Compared to understory S. senanensis, those grown in the open attained high photosynthesis and chlorophyll (Chl) a/b but lower area-based total chlorophyll, specific leaf area, and leaf nitrogen. In understory plants, these leaf characters and lightfleck responses indicated that they retain...

Characteristics of Sasa nipponica grassland as a summer forage resource for sika deer on Mt Ohdaigahara, central Japan

Recently, the sika deer, Cervus nippon Temminck, population has increased on Mt Ohdaigahara, central Japan. The dwarf bamboo, Sasa nipponica Makino et Shibata, is a primary forage plant for sika deer in this area. To demonstrate the characteristics of S. nipponica grassland, especially as summer forage for sika deer, the habitat use intensity of sika deer was estimated by fecal densities, and biomass, growth rate, removal by deer and crude protein content were examined. Sika deer utilized the S.␣nipponica grassland on Mt Ohdaigahara during summer when the biomass, growth rate and crude protein content of S. nipponica were high. The recent increase in the deer population seems to be partly due to S.␣nipponica grassland being a favorable summer habitat.

The effects of sika-deer browsing on the biomass and morphology of a dwarf bamboo, Sasanipponica, in Mt. Ohdaigahara, central Japan

We investigated the browsing effect of sika deer ( Cervus nippon Temminck) on the biomass and morphology of Sasa nipponica Makino et Shibata, a dwarf bamboo, in Mt. Ohdaigahara, central Japan. The investigation was performed through comparison of S. nipponica inside and outside a deer-proof fence. The S. nipponica outside the fence decreased in biomass (292.7 d.w.g./50×50 cm inside and 105.1 d.w.g. outside in August 1994), became miniaturized in culm height (49.1 cm inside and 15.6 cm outside), decreased in top leaf length (118.9 mm inside and 69.8 mm outside) and in culm diameter (2.0 mm inside and 1.2 mm outside) and densified in culm number (254/50×50 cm inside and 622 outside). After the destruction of the deer-proof fence, S. nipponica inside the fence underwent similar changes, that is, biomass decrease, miniaturization and densification in the next flush.

Seasonal changes in number and habitat use of foraging sika deer at the high altitude of Tanzawa Mountains, Japan

Seasonal changes in the population size and habitat use of sika deer Cervus nippon Temminck, 1838 in the high Tanzawa Mountains were studied. Deer exhibited seasonal movements different than those usually observed in the mountains. Because dwarf bamboo, their main winter food, recently occurs only in the high Tanzawa Mts, deer concentrated at the high altitude in late autumn and moved down in winter, after the reduction of bamboo biomass. The most utilized habitat types were forest clearings due to the highest food biomass available. Closed woodland was selected mostly in autumn and winter when deer often fed on fallen leaves and tree bark. Open woodland without bamboo in the understory was highly avoided. Sika deer population in the Tanzawa Mts should be kept at the stable level, which would enable recovery of vegetation. Because recent shrinking in bamboo distribution occurs mostly due to deer grazing pressure in winter, it was suggested to manage habitats in the low mountains in the way to make them attractive to deer also during winter. Supplemental feeding in the low mountains should be also considered.

地盤改良 現地ササ植生を材料とした寒冷地斜面保護工法の開発

Following a comprehensive field investigation on the effectiveness of slope protection techniques in cold regions, it was found that conventional protective grids usually cease to function within a few years because they protrude from the ground surface by repeated freeze and thaw cycles, and that such frost damages are significantly reduced on slopes covered by native dwarf bamboos (Sasa nipponica). Further, it was confirmed that the modified protective grids having a cross section shaped like “reverse T” are more effective in preventing frost damages than the conventional grids shaped like “I”. Based on these findings, an improved slope protection technique is recommended in which native dwarf bamboos are used as a ground cover protected by a new type of grids.

Regeneration and coexistence of two subalpine conifer species in relation to dwarf bamboo in the understorey

Abstract. Microhabitats for seedling establishment and gap regeneration in subalpine forests of northern Japan were studied for two conifers, Abies sachalinensis and Picea glehnii. The abundance of understorey dwarf bamboo (Sasa spp.) was different for the four plots examined. Two types of micro‐habitats were recognized for the two conifers: ground and elevated woody substrates (fallen logs and buttresses). Picea regenerated mostly on elevated sites, while Abies regenerated on both ground and elevated sites. The densities of Picea were independent of those of Sasa, but Abies densities decreased with increasing abundance of Sasa because Sasa reduced regeneration on the ground. Density of Abies on elevated sites was higher than that of Picea, irrespective of Sasa and of the density of adult trees. There was no significant difference in growth in sapling trunk height between the two conifers, but Picea grew more slowly under the canopy than Abies and was aggregated into gaps. Thus, in forests with less Sasa, the recruitment capacity of Abies was greater than that of Picea. The long life span of Picea compensated for its low density on elevated sites. Examination of a dynamic system model showed that Picea was excluded by Abies in forests without Sasa because regeneration on the ground is more advantageous than on elevated sites, but the two conifers could coexist in forests with Sasa because of the increased relative success of regeneration on elevated sites by Picea saplings.

Structure and composition of riparian forests with special reference to geomorphic site conditions along the Tokachi River, northern Japan

The structure and composition of riparian forests were examined along the Tokachi River, northern Japan. Both the hydrogeomorphic gradient and the temporal gradient were analyzed in attempt to explain the present pattern of riparian forests. The stability of floodplain surfaces was estimated on the basis of the elevation above the riverbed and the distance from the river channel. The characteristics of the substratum on which trees were established were also examined by excavation of buried sediment. The results indicated that soil moisture and organic content increased while the size of particles in the substratum decreased with increased elevation and distance from the river channel. Gradient analysis was employed to examine the distribution of dominant species, such as Alnus hirsuta, Toisusu urbaniana, Populus maximowiczii, Picea jezoensis and Abies sachalinensis. The relative dominance of each could be arrayed across the elevation gradient. Although the three broad-leaved pioneers dominated bars and floodplains near the river channel, their modes shifted from lower to higher elevation and amplitudes of distribution curves decreased in the following order: A. hirsuta, T. urbaniana, P. maximowiczii and conifers, which were located on the highest floodplains. Sites could be divided into three classes in terms of stability. There were fewer species at active sites, which favored the three pioneer species, but species richness and diversity increased with stand age. Semi-active and stable sites were more diverse with the establishment of conifers and other broad-leaved trees, which included upland species. However, species richness peaked and then decreased after trees reached 50 to 60 years of age. The growth of dwarf bamboo and the development of conifer-dominant stands impeded the establishment of other species, thereby reducing species richness and diversity in mature stands. Chronologically, floodplains could be differentiated into high- and low-frequency zones of flood disturbance, with pioneer species occupying the former, and late successional species found largely in the latter.

Role of the dwarf bamboo (Sasa) community in retaining basic cations in soil and preventing soil acidification in mountainous areas of Japan

Adjacent plots (1 m2) with and without communities of dwarf bamboo (Sasa), i.e. Sasa- and ref-plots, were selected in mountainous areas, which were relatively low in soil buffer capacity. The following parameters were studied: chemical properties of surface (0-30 cm) soil (at 6 sites), elemental abundances in the soil-Sasa ecosystem (at 6 sites), effect of artificial acid rain on the above two parameters (at 1 site), and chemical properties of throughfall and stemflow of Sasa (at 2 sites including one on a plain). Average values of pH(H2O), base saturation and the ratio of exchangeable (K+Mg+Ca)/exchangeable Al in surface soil were 4.35±0. 53, 25.2±14.3% and 0.41±0.28, respectively, in Sasa-plots and 4.26±0.63, 20.0±9.6%, and 0.28±0.13, respectively, in ref-plots. Though not significant, all soil parameters had higher values in Sasa-plots, i.e. Δx = ca. 0.1 unit, 5% and 0.13, respectively. When the abundance of elements (exchangeable cations in soil of 30 cm depth plus elements in litter and Sasa biomass) in the ecosystem was compared between the two plots, K (and often other basic cations) was higher in Sasa-plots than in ref-plots, whereas Al was lower. Artificial acid rain (1.5 L of 0.05 M H2SO4 applied monthly for 10 months) induced a reduction of Na, K, Mg and Ca in a ref-plot, but in a Sasa-plot only Na and K were reduced whereas Mg and Ca were completely retained. The composite samples of throughfall and stemflow of Sasa were ca. 0.5 higher in pH and richer in K, Mg and Ca than the ambient precipitation. The amounts (equivalents) of elements released by Sasa were in the order K > Ca > Mg. It was determined that about 87% and 98% of K, 76% and 87% of Ca, and 39% and 93% of Mg were of Sasa origin in the composite samples at a mountainous site (cambisol soil type) and a plain site (andosol soil type), respectively. Sasa communities may have a significant role in retention of basic cations in surface soil and prevention of soil acidification because of recycling elements in the soil-Sasa ecosystem.

Revegetation Patterns and Seedbank Structure on Abandoned Pastures in Northern Japan

To compare revegetation patterns between native and exotic species on abandoned pastures in northern Japan, we surveyed the vegetation structure and the seedbank using a flotation technique in 140 1 1 m plots. Previously introduced grasses such as Poa pratensis, Phleum pratense, and Dactylis glomerata were abundant 20 yr after the pasture abandonment, while Sasa senanensis, native shrub species, regenerated from propagation that had spread from the surrounding forests. S. senanensis shrublands and P. pratensis/P. pratense grasslands established on deep soils while D. glomerata grasslands established on shallow soils. Trees rarely became established on abandoned pastures. The seed density in the seedbank, representing 19 species, ranged from 542 to 2957 seeds/m2. The dominant species in the vegetation (P. pratensis, Trifolium repens, and Rumex acetosella) were also common in the seedbank, whereas Cerastium holosteoides var. angustifolium, Chenopodium album var. centrorubrum, and Erigeron canadensis were widespread in the seedbank but did not occur in the extant vegetation. S. senanensis regenerated by vegetative propagation, and P. pratensis and P. pratense developed a seedbank. We concluded that for native species, particularly S. senanensis, vegetative reproduction has an important role on revegetation rather than regeneration from the seedbank, and the dwarf bamboo may be a keystone species in the ecosystems.

Revegetation patterns and seedbank structure on abandoned pastures in northern Japan

To compare revegetation patterns between native and exotic species on abandoned pastures in northern Japan, we surveyed the vegetation structure and the seedbank using a flotation technique in 140 1 1 m plots. Previously introduced grasses such as Poa pratensis, Phleum pratense, and Dactylis glomerata were abundant 20 yr after the pasture abandonment, while Sasa senanensis, native shrub species, regenerated from propagation that had spread from the surrounding forests. S. senanensis shrublands and P. pratensis/P. pratense grasslands established on deep soils while D. glomerata grasslands established on shallow soils. Trees rarely became established on abandoned pastures. The seed density in the seedbank, representing 19 species, ranged from 542 to 2957 seeds/m2. The dominant species in the vegetation (P. pratensis, Trifolium repens, and Rumex acetosella) were also common in the seedbank, whereas Cerastium holosteoides var. angustifolium, Chenopodium album var. centrorubrum, and Erigeron canadensis were widespread in the seedbank but did not occur in the extant vegetation. S. senanensis regenerated by vegetative propagation, and P. pratensis and P. pratense developed a seedbank. We concluded that for native species, particularly S. senanensis, vegetative reproduction has an important role on revegetation rather than regeneration from the seedbank, and the dwarf bamboo may be a keystone species in the ecosystems.

Gnawing damage by rodents to the seedlings of Fagus crenata and Quercus mongolica var. grosseserrata in a temperate Sasa grassland‐deciduous forest series in southwestern Japan

AbstractThe effects of dwarf bamboo, Sasa, cover on the initial morrality of hardwood seedlings were investigated by transplanting 1‐year‐old beech (Fagus crenata) and current‐year oak (Quercus mongolica var. grosseserrata) seedling to three different stands; old‐growth beech and secondary oak forests with Sasa undergrowth, and a Sasa grassland in a grassland‐forest series near the top of Mt Jippo, southwestern Japan. The most frequent cause of seedling morrality was gnawing of the stems by rodents. In the beech forest, the gnawing was more likely to occur under Sasa cover, suggesting that it provides a good habitat for rodents on the beech forest floor. The Sasa under growth may thus play an imporrant role in regeneration of beech forest. In the oak floor, mortality of both species was low and only a little gnawing occurred during a year. However, no natural oak seedling were found in the forest even after a mast year. This may be because most of the acorns disappeated before establishment. The early‐stage demography of hardwood seedling as oak may thus play an imporrant role in regeneration of oak forest. In the Sasa grassland where the seed supply is small, almost all of the seedlings died fromo gnawing regardless of the presence of Sasa cover. These factors prevent the recruitment of a sizable seedling bank. Rodents may thus play an imporrant role in maintenance of the Sasa grassland.