Dwarf Bamboo Research Articles

Seasonal changes in the digestion and passage rates of fresh dwarf bamboo ( Pleioblastus argenteostriatus f. glaber) in sheep

The aim of this study was to determine and characterize the ruminal degradability and passage rate of fresh dwarf bamboo ( Pleioblastus argenteostriatus f. glaber) cut in spring and autumn, to study the influence of these variables on intake and digestibility by sheep. The experiment was conducted in late spring (May to early June) and autumn (late September to early October). Eight Suffolk ewes, surgically fitted with ruminal cannulae, were used to measure the ruminal degradability and passage rate. Half of the animals received fresh dwarf bamboo and the other half fresh bahiagrass twice daily to meet maintenance requirements. In spring, the lignin content of dwarf bamboo was similar to that of bahiagrass and approximately twice that of bahiagrass in autumn. The slowly degradable fraction of dry matter (DM) and neutral detergent fiber (NDFom) was lower in dwarf bamboo than in bahiagrass. This fraction decreased in dwarf bamboo in the autumn, in contrast to bahiagrass which maintained similar levels as in the spring (Grass × Season interaction; P=0.005 and 0.016 for DM and NDFom, respectively). However, no difference was observed in degradation rate between grasses and seasons. The degradation rate of crude protein (CP) in dwarf bamboo was lower than that of bahiagrass, particularly in autumn. The ruminal passage rate was unaltered by the type of grass and season. DM intake was similar between the grasses, although a seasonal decrease was observed in both the grasses (P=0.006). The digestibility of DM and NDFom were clearly lower in dwarf bamboo than in bahiagrass (P<0.001) and digestibility decreased in autumn (P<0.05) in both grasses. Seasonal variation in DM intake and digestibility of bahiagrass was independent of ruminal degradation characteristics, but in dwarf bamboo both variables were associated with lower potential degradability in the rumen and higher cell wall lignification. However, besides lignin, other non-identified factors also may have contributed to depress ruminal digestion of dwarf bamboo as suggested by the comparison with bahiagrass in spring at similar levels of lignification.

Effects of deer and mice on seedling survival in a temperate mixed forest of Japan

To detect the magnitude of indirect positive effects of deer and mice on seedling survival of some woody species in a Japanese temperate forest, we analyzed the data from an earlier field experiment using a hierarchical Bayesian approach. The forest studied was inhabited by sika deer ( Cervus nippon) and mice ( Apodemus spp.), and the floor was covered with dwarf bamboo, Sasa nipponica, which negatively affected tree seedlings and was in turn negatively affected by deer and mice. The field experiment was designed as the combination of exclusion or removal of these factors: deer, mice and dwarf bamboo. A hierarchical Bayesian model was constructed and the parameters were estimated by the Markov chain Monte Carlo method. The model successfully showed the indirect positive effects of deer and mice, which improved the survival rate of five cohorts of the seedlings of three tree species by ameliorating the direct negative effect of dwarf bamboo. The cohorts studied were formed by the seedlings of Abies homolepis that emerged in 1997 and 2002, those of Fraxinus lanuginosa f. serrata that emerged in 1998 and 2002, and those of Fagus crenata that emerged in 1999. The positive indirect effect was especially large in F. crenata, which is known to be severely affected by dwarf bamboo. The total effect of deer was shown to be positive for all cohorts except the A. homolepis cohort that emerged in 1997, at which time the dwarf bamboo had not yet fully recovered from the browsing pressure of deer. The total effect of mice was shown to be positive for all of the cohorts. We conclude that these positive effects were due to the large negative effect of dwarf bamboo on the seedlings.

Effects of stand, landscape, and spatial variables on bird communities in larch plantations and deciduous forests in central Japan

We examined the effects of stand, landscape, and spatial variables on bird communities in deciduous forests and Japanese larch ( Larix leptolepis (Sieb &amp; Zucc.) Gord.) plantations in a montane region of Nagano Prefecture, central Japan. We used plot-transect methods at 97 sites: 33 in winter 2003 and 18 sites were added in the 2004 breeding season in deciduous forests, and 32 in winter 2004 and 14 sites were added in the 2005 breeding season in larch plantations. Bird–environment relationships were explored using partial redundancy analysis and partial regression analysis. We used spatial variables derived from principal coordinates of neighbor matrices as explanatory variables to detect nonrandom spatial structure of bird communities. Variation in bird communities was mainly explained by stand and spatial variables for both forest types, whereas the effects of landscape variables were small. In plantations, important stand variables for both seasons included stand height, elevation, and the basal area of vines, whereas shrubs, dwarf bamboo ( Sasa senanensis (Franch. &amp; Savat.) Rehd.), and larch snags were important in the breeding season. In deciduous forests, the most important stand variable for both seasons was the basal area of northern Japanese hemlock ( Tsuga diversifolia (Maxim.) Mast.) and Nikko fir ( Abies homolepis Sieb. &amp; Zucc.) trees. Spatial variables showed that bird communities had large-scale (&gt;10 km) spatial variation that could not be explained by stand or landscape variables.

Reforestation of abandoned pasture on Hokkaido, northern Japan: effect of plantations on the recovery of conifer-broadleaved mixed forest

When pasture land is abandoned, there are, in many cases, inhibitory factors that slow the rate of transition to a natural vegetation. Accordingly, the planned management of restoration has become an important issue in various parts of the world, where environmental conditions can vary widely. Although tree plantations are widely used as a management tool for restoration, there have been few studies addressing the practical aspects of the procedure. I examined effects of tree plantations within the framework of an evaluation of methods for restoring abandoned pasture on Hokkaido, northern Japan. I developed and analyzed vegetation maps spanning the past 57 years for the old-growth site influenced by artificial disturbance; the procedure revealed the pattern of change in the vegetation cover. Matrix model analysis showed that intensive use of plantations contributed to reduction of the area occupied by dwarf bamboo and pasture land (i.e., superior to simple abandonment). Furthermore, the field study of vegetation types and changes in species composition over 20 years suggests that plantations have contributed to a reduction in the effects of factors that inhibit revegetation. However, the establishment of monoculture plantations is frequently viewed skeptically as a procedure that is applied without fundamental ecological knowledge. For sustained management, adequate historical and ecological information on the restoration site should be provided to all stakeholders.

Removal of understory dwarf bamboo (Sasa kurilensis) induces changes in water-relations characteristics of overstory Betula ermanii trees

We investigated how removal of understory dwarf bamboo (Sasa kurilensis Makino et Shibata) affected growth and water use of young Betula ermanii Cham. trees in a secondary forest in northern Japan. We compared current-year shoot morphology, leaf water-relations characteristics, and whole-tree water use of B. ermanii trees growing with dwarf bamboo in the understory (intact plot) to those of trees growing where dwarf bamboo was experimentally removed (removal plot). Current-year shoot length and internode frequency increased, while internode length and individual leaf area decreased in response to dwarf bamboo removal. Carbon isotope composition (δ13C) of leaves did not change indicating that leaf water-use efficiency was unaffected by the presence/absence of dwarf bamboo. Pressure–volume analysis indicated that leaves in the removal plot had lower water uptake ability. During mid-summer, trees in the removal plot sustained high sap flow velocity after peaking at midday, while that of trees in the intact plot declined. In addition, whole-tree sap flux and soil-to-leaf hydraulic conductance were both higher for trees in the removal plot. We inferred that the observed changes reflect hydraulic homeostasis of B. ermanii trees to maintain constant water-use efficiency in response to belowground competition with dwarf bamboo. Removal of dwarf bamboo is, therefore, an effective silvicultural prescription to enhance growth of overstory trees by relieving belowground competition for soil water.

Forage selection by beef cows grazed on a dwarf bamboo (Pleioblastus argenteostriatus f. glaber)‐dominant pasture

AbstractThis study investigated the influence of forage selection on the quality of the diet ingested by beef cows grazed on a dwarf bamboo‐dominated pasture. For 13 days each in spring, summer and autumn, eight Japanese Black cows were grazed on a 1.8‐ha dwarf bamboo (Pleioblastus argenteostriatus f. glaber)‐dominant pasture during the day. The plant species and number of bites of each species ingested by the cows were recorded, and plant samples were hand plucked to imitate the behavior of the cows during the grazing time on the seventh and 13th days of each period. The botanical and chemical compositions of the available pasture were systematically estimated by sampling 28 plots. The cows slightly avoided dwarf bamboo and preferred grasses on the seventh day of each period. On the 13th day, the cows ate any available forage in the pasture. The selected forages were higher in crude protein and in vitro digestibility and had lower insoluble protein, neutral detergent fiber and lignin contents than the forages available in the pasture during a season. The frequency of the botanical groups selected by the cows was different in autumn from that in spring and summer, and a substantial increase in grasses and a decrease in P. argenteostriatus f. glaber among the selected forages were observed. Although the botanical groups selected by the cows were relatively different between the seasons, an increase in the levels of unavailable fractions such as lignin and insoluble protein and a decrease in in vitro digestibility were observed as the seasons progressed. Thus, the cows could not avoid a decrease in their diet quality in autumn. The selection of forage improved the nutrient intake of the beef cows in terms of chemical and digestible components; however, in a dwarf bamboo‐dominated pasture, there is a substantial limitation in the effectiveness of forage selection.

Utility of spectral vegetation indices for estimation of light conversion efficiency in coniferous forests in Japan

To clarify the utility of spectral vegetation indices (VIs) for estimating light conversion efficiency ( ɛ) in Japanese coniferous forests, we investigated the relationships between six VIs (NDVI, EVI, SAVI, PRI, CI, and CCI) and ɛ in two mature monospecific forests of deciduous conifer (Japanese larch) and evergreen conifer (Japanese cypress) and one young mixed stand of deciduous conifer with evergreen undergrowth (hybrid larch and dwarf bamboo). In each forest canopy, we measured seasonal variations in CO 2 flux, radiation environment, and visible–near-infrared spectral reflectance during 1 or 2 growing seasons. We calculated ɛ as gross primary production (GPP) divided by the difference between incoming and reflected photosynthetically active radiation (PAR). VIs and ɛ under clear skies were averaged between 11:00 and 13:00 JST and their relationships were analyzed. In the larch forest, all calculated VIs were positively correlated with ɛ, and the highest correlation was that with CCI. Because of effects of extreme reduction in PRI in autumn with needle yellowing, the correlation of ɛ and PRI was relatively small in this forest. In the cypress forest, on the other hand, no significant correlation was found except with PRI and CCI. The highest correlation in this forest was that with PRI, suggesting that the leaf biomass-related VIs based on near-infrared reflectance are not sufficient for estimating ɛ of evergreen forest. In the mixed forest, with relatively sparse vegetation cover, all VIs were significantly correlated with ɛ, but the best correlation was that with SAVI, possibly owing to the reduction in the effect of the reflectance from background soil. Correlation analysis of the pooled data from all forests showed the highest correlation between ɛ and PRI. These results indicate that PRI is an effective VI in the remote estimation of ɛ in both deciduous and evergreen forests, although there are some sensitivity differences between vegetation types.

ニホンジカによるスズダケ退行地において植生保護柵が高木性樹木の更新に及ぼす効果―植生保護柵設置後７年目の結果から―

ニホンジカによるスズダケ退行地において植生保護柵が高木性樹木の更新に及ぼす効果―植生保護柵設置後７年目の結果から―

「ニホンジカによる森林の変化が昆虫類に及ぼす影響」シカの採食がササにゴールを形成するタマバエとその寄生蜂２種に与える間接効果

奈良県大台ヶ原において，ニホンジカ（Cervus nippon）の主要餌であるミヤコザサ（Sasa nipponica）の稈にゴールを形成するタマバエ（Oligotrophini族）の生残と，これに寄生する2種の寄生蜂，Pediobius sasaeとTorymus sp.の寄生を防鹿柵内外で比較した。シカの採食は間接的にゴールの幅を小さくしていた。防鹿柵内では柵外と比べるとタマバエの生残率が高く，Torymus sp.の寄生率も高かったが，P. sasaeの寄生率は低かった。P. sasaeの寄生は，防鹿柵内では幅の小さなゴールに集中していたが，柵外ではゴール幅に関係なかった。Torymus sp.はP. sasaeよりも産卵管が長く，羽化が短期間で完了した。これらのことから，タマバエとTorymus sp.は，P. sasaeの短い産卵管では届かないような大きなゴール内では生残でき，これが防鹿柵内外の生残率と寄生率の違いを生じさせていると考えられた。このように，シカによるミヤコザサの採食は，間接的にゴール幅を小さくし，P. sasaeの寄生を助長して，タマバエの生残とTorymus sp.の寄生を妨げていた。

Classification and comparison of oak dominated forests on the eroded fan remnant at the foot of Yatsugatake volcano, central Japan

In order to evaluate the landform-mediated differences in the regeneration of oak ( Quercus crispula), we compared the composition and diameter distribution of 77 stands on an eroded fan remnant at the foot of Yatsugatake volcano in central Japan. In total seven site units were classified on the basis of the combination of the vegetation, topography and soil data. Overall, the patterns of compositional change were strongly related to the topographic and edaphic differences among fluvial landforms. Oak dominated the units on the older-fan surfaces: mounds, depressions, rock outcrops and side slopes, but it was rare in the units on the valley floor: stream terraces, natural levees of coarse rock fragments and seeps. The units on the older-fan surfaces, except for rock outcrops, were covered by fine fertile organic soils (Andisols), while coarser fluvial deposits covered the units on the valley floors. Oak was most abundant on the mounds followed by the depressions, rock outcrops and side slopes. Oak sapling density was low even in oak stands, and it was very low on well-drained sites with high abundances of shade-tolerant trees. Sapling and seedling abundance of these shade-tolerant tree species were high on side slopes and rock outcrops but low on Andisols with thick humus layer and in areas with dense dwarf bamboo ( Sasa nipponica) coverage. Under the current conditions of reduced disturbance frequency, we predict that Q. crispula will be replaced by shade-tolerant tree species, especially on side slopes and rocky outcrops.

Effects of fine-scale simulation of deer browsing on soil micro-foodweb structure and N mineralization rate in a temperate forest

The effects of low densities of native browsing mammals on nutrient cycling are not fully understood. Weak browsing may improve nitrogen (N) mineralization in soil and positively affect plant regrowth at the forest floor. To investigate the effects of weak browsing by sika deer ( Cervus nippon) on soil subsystems, we defoliated a dwarf bamboo ( Sasa nipponica)-dominated understory layer in a natural forest at different intensities to realistically simulate deer browsing. Defoliation (0–18% leaf removal) was performed three times at approximately 1-week intervals in summer. We measured water-soluble carbon (C) concentration, phospholipid fatty acid (PLFA) profiles as indicators of microbial community structure, a PLFA of 20:4 as an indicator of protozoan abundance, nematode community structure at the family level, and the N mineralization rate in 28 days of incubation. The effects of defoliation on each soil parameter were determined by comparing before and after defoliation values. The N mineralization rate in the first 10 days of incubation showed a unimodal response to defoliation intensity, with a peak mineralization rate at a defoliation rate (number of removed leaves/total leaves) of 7.6%, correlating with protozoan PLFA and the abundance of Plectidae (the most dominant family of bacterivorous nematodes). In contrast, the N mineralization rate during the following 18 days of incubation decreased monotonically with increasing defoliation intensity, correlating with the water-soluble C concentration in the soil and the C content of new leaves. These results suggest that removing <15% of leaves may have induced a pulse-like release of labile organic matter from roots that lasted for less than 1 week and stimulated N mineralization through microbial loop in soil in the short term (in the first 1–2 weeks after defoliation). N mineralization, however, was reduced with increase of defoliation intensity in the longer term (3–5 weeks after defoliation), possibly because of the reduction in labile organic matter supply from roots 1 week after defoliation. As a result, N mineralization rates over the 28-day incubation period responded to defoliation intensity in a unimodal pattern with a small peak (at a defoliation rate of 4.9%) and were negatively affected by high defoliation rates (>10%). This study suggests that browsing on forest floor plants has positive or negative effects on soil N mineralization potential depending on browsing intensity level.

Life cycles and interactions in spider mites (Acari: Tetranychidae) on dwarf bamboo, Sasa senanensis (F. & S.) (Poaceae), in Japan

To clarify the interactions among mite species coexisting on the same plant, we determined the population dynamics of five spider mites (Acari: Tetranychidae) and their predators (Phytoseiidae, Stigmaeidae) appearing on dwarf bamboo, Sasa senanensis (Franchet and Savatier) (Poaceae), which has a high degree of structural heterogeneity in leaf pubescence. Tetranychid mites, Aponychus corpuzae Rimando, Panonychus bambusicola Ehara and Gotoh and Stigmaeopsis longus (Saito) preferred glabrous leaves, whereas Schizotetranychus recki Ehara and Yezonychus sapporensis Ehara, and the predators Agistemus summersi Ehara (Stigmaeidae) and Phytoseius tenuiformis Ehara (Phytoseiidae) preferred hirsute leaves. Species living on glabrous leaves tended to avoid species living on hirsute leaves. However, three species that prefer glabrous leaves sometimes coexisted with and sometimes avoided species that prefered hirsute leaves. Each species probably has some range of leaf hairiness that they tolerate and prefer. The presence of leaf hairs along the midvein of the lower surfaces of the leaves are especially important because they increase the acceptable range for coexistence of species preferring glabrous or hirsute leaves. Stigmaeopsis longus coexisted with Typhlodromus bambusae Ehara, which is a species-specific predator of St. longus. Yezonychus sapporensis coexisted with Ag. summersi, which is a predator of Y. sapporensis and Sc. recki. The population density of each spider mite species produced one to three peaks in spring, autumn and/or early winter depending on the species and the census periods. Phytoseius tenuiformis accounted for most of the phytoseiid mites on Sasa leaves and occurred on the most hirsute leaves. Almost all phytoseiid mites collected in the nests of the spider mite St. longus were T. bambusae. The critical photoperiods of five spider mite species ranged from 13.5 to 14.5 h at 18°C, which occured between late August and mid-September in Sapporo. The dates by which 50% or more individuals entered diapause were between late August and late September, roughly corresponding with timing predicted by the critical photoperiods. The maximum number of generations that could be produced in a year was estimated as four or five based on the total degree-days accumulated above the lower temperature threshold (10.2-12.1°C) of five spider mite species and the thermal constant (164.5-217.7 DD) of these mite species.

Regeneration responses influenced by single-tree selection harvesting in a mixed-species tree community in northern JapanThis article is one of a selection of papers published in the Special Forum IUFRO 1.05 Uneven-Aged Silvicultural Research Group Conference on Natural Disturbance-Based Silviculture: Managing for Complexity.

The objective of this study was to assess the effects of fine-scale canopy disturbances induced by selection harvesting and its associated practices (artificial planting and machinery skidding) on the successful regeneration of tree species in a northern Japanese mixed forest. We set up 163 plots in a 6.7 ha permanent study stand where trees have been partially harvested at approximately 10-year intervals since 1974. The regeneration of trees (4324 stems·ha–1) occurred more frequently under closed canopies than under canopy gaps, except for a typical shade-intolerant species, Betula ermanii Cham. In particular, small canopy openings that tend to close quickly displayed higher understory tree regeneration densities likely due to the suppression of competition from dwarf bamboos. The surface soil disturbances that occurred during planting and harvesting even further enhanced understory regeneration. The results shown here should be generalized carefully because we have investigated only one stand. Nevertheless, our findings clearly indicated that the creation of small canopy gaps associated with site preparation that contains soil disturbances should be examined in management practices to maintain the community structure in this type of mixed forest.

Ramet population structure of Fargesia nitida in different canopy conditions of the subalpine dark coniferous forest in the Wolong Nature Reserve, China

The bamboo Fargesia nitida, one of the giant panda’s main food sources and the dominant shrub species of the forest understory, is mainly distributed in the dark coniferous belt in western Sichuan and southern Gansu in China. To study the impact of different forest canopy conditions on subalpine dwarf bamboo populations, ramet population structures of clonal Fargesia nitida were surveyed in: forest understory (FU), moderate gap (MG), large gap (LG) and marginal open space (MOS). In order to determine how the ramet structures could be affected and its effects on these four canopy conditions, a field survey of the age structure of Fargesia nitida population, its morphological traits and biomass was conducted in the Abies faxoniana forest situated in the Wolong Nature Reserve, western Sichuan, China. The main results were as follows. First, at the ramet level, the structures of the ramet populations in four canopy conditions were significantly different, and as the canopy density decreased, the mean height, basal diameter and biomass of the populations increased following the order: LG 0.05). All the results indicated that it was not ramet age, but the morphological changes and biomass distribution that exhibited the response of the ramet population of Fargesia nitida to the changed canopy conditions.

Seasonal variation of nutrient intake and digestibility of forage in beef cows grazed on a dwarf bamboo (Pleioblastus argenteostriatus f. glaber) dominant pasture

AbstractDwarf bamboo is a significant but unique native forage for cattle grazing in Japan. A pasture dominated by Pleioblastus argenteostriatus f. glaber, a type of dwarf bamboo, was used to evaluate nutrient intake, digestibility of forage and nutritional status of grazing cows. Eight Japanese Black cows were grazed on the pasture, and six among the eight grazing cows were used for the experiment. This experiment consisted of three periods: spring (May), summer (July) and autumn (September–October) in 2002 and 2003. The nutrient intake and digestibility of the cows were estimated by the double indicator method with chromic oxide (Cr2O3) as the external indicator and acid detergent insoluble ash (ADIA) in forages as the internal indicator. The crude protein (CP) and neutral detergent fiber (NDF) contents of forage selected by the cows hardly changed during the grazing seasons in both years. Crude ash, acid detergent lignin (ADL), ADIA, and acid detergent insoluble protein (ADIP) contents were the highest in autumn in both years. Nutrient intake of the cows was lower in autumn than in other seasons. Nutrient digestibility of the cows increased slightly from spring to summer and then decreased in autumn. Metabolizable energy (ME) intake satisfied the maintenance requirements of the cows in spring and summer; however, it was only 50%–70% of the maintenance in autumn for both years. Urea nitrogen concentration in plasma was always high, approximately 20 mg dL−1, during grazing periods. Inorganic phosphate (IP) concentration in plasma was lower than critical value (4.5 mg dL−1) in spring and autumn. Therefore, energy and phosphate supplementation are needed for the cows grazed on P. argenteostriatus f. glaber‐dominated pasture.

Effects of tree cutting and mowing on plant species composition and diversity of the wetland ecosystems dominated by the endangered maple, Acer pycnanthum

Japanese red maple, Acer pycnanthum, is an endangered species that grows only in small, discrete wetland ecosystems in central Honshu, Japan. Because of its rarity and beauty, public attention and management are typically focused only on this overstory species. For example, mowing and tree cutting of understory and ground-cover plants are practices frequently applied to develop easily accessible, park-like stands. To examine the ecological effects of these practices and discuss the role of silvicultural practices in conservation of these ecosystems, plant species composition and diversity were studied at six, unmanaged near-natural ecosystems, and they were compared with that of one managed ecosystem where tree cutting and mowing have been conducted. In addition, changes of plant species composition and diversity were investigated at one site where tree cutting was conducted. Results indicated that the near-natural ecosystems are characterized by high plant species diversity, consistent occurrence of endangered and endemic species, and virtual lack of non-native species. Plant species diversity was markedly greater in the understory and ground-cover layers than in the overstory, which was characterized by high abundance of large maple trees. In contrast, at the ecosystem where tree cutting was conducted and the ground cover annually mowed for 18 years, stem density and diversity of the understory layer were extremely low compared to those of the near-natural ecosystems. In the ground-cover layer, the species composition was markedly different from that of the near-natural ecosystems due to the presence of non-native species and species favoring open, disturbed habitats. After two years at the ecosystem where tree cutting only was conducted, a significant decrease of diversity index H′ was recorded in the ground cover. The decrease was in large part due to the spread of dwarf bamboo, which was favored by increased light irradiance. At both managed ecosystems, regeneration of Japanese red maple was lacking. Because of these dramatic changes, intensive silvicultural practices should be restricted to a few exceptional places where public interest is paramount. I recommend that silvicultural practices only be used for significant and specific conservation purposes, such as removal of invasive species. Special concern regarding the spread of dwarf bamboo is required when managers plan tree cutting at sites where the bamboo grows within or adjacent to the site.

Biometric Based Carbon Flux Measurements and Net Ecosystem Production (NEP) in a Temperate Deciduous Broad-Leaved Forest Beneath a Flux Tower

Biometric based carbon flux measurements were conducted over 5 years (1999–2003) in a temperate deciduous broad-leaved forest of the AsiaFlux network to estimate net ecosystem production (NEP). Biometric based NEP, as measured by the balance between net primary production (including NPP of canopy trees and of forest floor dwarf bamboo) and heterotrophic respiration (RH), clarified the contribution of various biological processes to the ecosystem carbon budget, and also showed where and how the forest is storing C. The mean NPP of the trees was 5.4 ± 1.07 t C ha−1 y−1, including biomass increment (0.3 ± 0.82 t C ha−1 y−1), tree mortality (1.0 ± 0.61 t C ha−1 y−1), aboveground detritus production (2.3 ± 0.39 t C ha−1 y−1) and belowground fine root production (1.8 ± 0.31 t C ha−1 y−1). Annual biomass increment was rather small because of high tree mortality during the 5 years. Total NPP at the site was 6.5 ± 1.07 t C ha−1 y−1, including the NPP of the forest floor community (1.1 ± 0.06 t C ha−1 y−1). The soil surface CO2 efflux (RS) was averaged across the 5 years of record using open-flow chambers. The mean estimated annual RS amounted to 7.1 ± 0.44 t C ha−1, and the decomposition of soil organic matter (SOM) was estimated at 3.9 ± 0.24 t C ha−1. RH was estimated at 4.4 ± 0.32 t C ha−1 y−1, which included decomposition of coarse woody debris. Biometric NEP in the forest was estimated at 2.1 ± 1.15 t C ha−1 y−1, which agreed well with the eddy-covariance based net ecosystem exchange (NEE). The contribution of woody increment (Δbiomass + mortality) of the canopy trees to NEP was rather small, and thus the SOM pool played an important role in carbon storage in the temperate forest. These results suggested that the dense forest floor of dwarf bamboo might have a critical role in soil carbon sequestration in temperate East Asian deciduous forests.

Holocene Phytolith Record at Picea glehnii Stands on the Dorokawa Mire in Northern Hokkaido, Japan

Phytolith analysis was applied to clarify a vegetation history at Picea glehnii stands on the Dorokawa Mire, northern Hokkaido. Phytolith assemblages from surface samples and Holocene deposits from the mire are used to clarify the stand-scale vegetation history, with special focus on the dynamics of Gramineae, which includes dwarf bamboo, and the establishment of P. glehnii stands on the mire. The phytolith records during the early-Holocene (ca. 12,000 to 10,000 cal BP) indicate the distribution of Pooideae-dominated vegetation, which reflects the cool climate. Phragmites (reed) dominated vegetation from the early to mid-Holocene (ca. 10,000 to 5,000 cal BP) suggests wet conditions like low-moor. The reed was replaced by dwarf bamboo at ca. 5,000 cal BP, although the distribution of dwarf bamboo was scattered. At ca. 1,500 cal BP, dwarf bamboo increased abruptly and has been sustained to the present. Also, Pinaceae type phytoliths began to occur continuously at ca. 1,000 cal BP. Taking into account the relationship between modern vegetation and modern phytolith assemblages on the mire, the occurrence of the Pinaceae type phytoliths from the sediment samples indicates the existence of P. glehnii in the study sites. On the basis of these results, P. glehnii stands with dense undergrowth of dwarf bamboo would have been established in the study sites on the mire by ca. 1,000 cal BP at least.

EFFECTS OF FARGESIA NITIDA ON REGENERATION OF ABIES FAXONIANASEEDLINGS NEAR THE EDGE OF SUBALPINE DARK CONIFEROUS FOREST

Aims Many researches have shown that the interlaced roots of dwarf bamboo (Fargesia nitida) can influence the regeneration of trees and the growth of seedlings and saplings through competition for light, water and nutrients. We explore the effect of dwarf bamboo on the regeneration of Abies faxoniana on the forest edge and estimate the effect of dwarf bamboo on the dispersal and community development. We asked: 1) how will quantitative characteristics and population structure change under different densities of F. nitida, and 2) how will the density of F. nitida influence the growth and biomass allocation of A. faxoniana seedlingsMethods We sampled five belt transects and analyzed 30 plots within each transect in Wolong Giant Panda Nature Reserve (30°51′41″ N,102°58′21″ E) during August and September 2005. The transects were selected based on different densities of F. nitida (i.e., distance to the F. nitida cluster): 2 m outside the cluster (Zone 1), 1 m outside the cluster (Zone 2), 1 m inside the cluster (Zone 3), 2 m inside the cluster (Zone 4) and 3 m inside the cluster (Zone 5). We measured the height, basal diameter and crown of each A. faxoniana seedling. We used five BD classes: Ⅰ (0BD0.3 cm), Ⅱ (0.3 cm≤BD0.6 cm), Ⅲ (0.6 cm≤BD0.9 cm), Ⅳ (0.9 cm≤BD1.2 cm), Ⅴ (BD≥1.2 cm), and five size classes: Ⅰ (0H15 cm), Ⅱ (15 cm≤H30 cm), Ⅲ (30 cm≤H45 cm), Ⅳ (45 cm≤H60 cm), and Ⅴ (H≥60 cm). The seedlings were divided into two groups, large (H0.2 m) and small (H≤0.2 m), to explore the accumulation and allocation of biomass by A. faxoniana seedlings. We obtained data on biomass from regression equations based on a sample of 60 A. faxoniana seedlings.Important findings Regeneration and growth of A. faxoniana seedlings were restrained in the F. nitida-dominated zones, and dispersal of the A. faxoniana population and development of an A. faxoniana-dominated community were affected. Closer to F. nitida clusters, the number of old seedlings and the efficiency of transformation (seedling number ratio of the next BD class to the preceding BD class) were reduced (the older the A. faxoniana seedlings, the smaller the efficiency of transformation); the peak of number of seedlings moved from larger (Ⅲ) to the smallest size (Ⅰ); the total biomass and allocation of biomass aboveground of A. faxoniana seedlings decreased; and the presence of F. nitida restrained the height growth of small (Ⅰ) A. faxoniana seedlings (confirmed by regression of basal diameter and height). The expansion of crowns of bigger (Ⅲ) seedlings increased in moderate density (Zone 4) of F. nitida.

Meso-scale variation in winter food composition of sika deer in Tochigi Prefecture, central Japan

Food habits of sika deer Cervus nippon show great variations at a macro-scale geographical range and some variations even at micro-scale of locations such as islands or mountains, but there is no study at meso-scale. We investigated variation in the food habits of sika deer over a meso-scale range encompassing high mountains and hilly areas in Tochigi Prefecture, central Japan. Rumen contents sampled from deer culled in the winter of 1996 (n = 147) in 10 localities were analyzed using the point-frame method. Local variation in food composition was high. Detrended correspondence analysis (DCA) showed that food composition varied from the western high mountain region, where low quality foods (dead leaves, bark, and culms) were dominant, to northern and eastern areas, where a dwarf bamboo Sasa nipponica, which grew in the understory of oak forests, was dominant. Two intermediate localities between the western and eastern areas and another eastern locality fell between the western high area and the eastern low area in the ordination. The proportion of S. nipponica varied from 0% to 99% among all samples, and from 0.5% to 60% among the 10 localities. S. nipponica occupied >50% of rumen contents in 52 samples (35.4%). Thus, the food habits of sika deer varied greatly, even within a meso-scale range of 2000 km2, depending on food availability in the different habitats.