Sasa Kurilensis Research Articles

Biomagnetic monitoring of the spatial distribution of atmospheric particulate matter in an industrialized city in Japan: Case study at Muroran

<p>Japan has 111 active volcanoes, supplying a great amount of magnetically-enhanced fly ashes. Such fly ashes likely mask anthropogenic magnetic signals; therefore, only a few magnetic biomonitoring studies have been reported in active volcanic regions, including Japan. The environmental magnetic results are reported for the materials deposited on Sasa Kurilensis, also known as dwarf bamboo, in the vicinity of the industrialized Muroran city center in Japan. The dust on the ten leaves at 105 sites was wiped off with a commercial wipe sheet, and their rock magnetic properties were analyzed. Room- and low-temperature magnetic analyses indicate that the major magnetic mineral in the dust is partially oxidized magnetite, ranging from single to pseudo single domain size, and the magnetic mineralogy on the leaves’ surface remains consistent throughout the study area. Much higher saturation isothermal remanent magnetization intensities are observed in the city’s eastern parts. The dominant wind directions in Muroran city are northwest, indicating that the steel companies in the city center are the major source of the fine-grained magnetic minerals on the dwarf bamboo leaves. These results indicate that using the leaves of dwarf bamboo for magnetic biomonitoring can be a non-destructive and rapid method to study the spatial distribution of atmospheric particulate matter from local industrial activities, even in active volcanic areas.<strong></strong></p>

Biomagnetic monitoring of the spatial distribution of atmospheric particulate matter in an industrialized city in Japan: Case study at Muroran

<p>Japan has 111 active volcanoes, supplying a great amount of magnetically-enhanced fly ashes. Such fly ashes likely mask anthropogenic magnetic signals; therefore, only a few magnetic biomonitoring studies have been reported in active volcanic regions, including Japan. The environmental magnetic results are reported for the materials deposited on Sasa Kurilensis, also known as dwarf bamboo, in the vicinity of the industrialized Muroran city center in Japan. The dust on the ten leaves at 105 sites was wiped off with a commercial wipe sheet, and their rock magnetic properties were analyzed. Room- and low-temperature magnetic analyses indicate that the major magnetic mineral in the dust is partially oxidized magnetite, ranging from single to pseudo single domain size, and the magnetic mineralogy on the leaves’ surface remains consistent throughout the study area. Much higher saturation isothermal remanent magnetization intensities are observed in the city’s eastern parts. The dominant wind directions in Muroran city are northwest, indicating that the steel companies in the city center are the major source of the fine-grained magnetic minerals on the dwarf bamboo leaves. These results indicate that using the leaves of dwarf bamboo for magnetic biomonitoring can be a non-destructive and rapid method to study the spatial distribution of atmospheric particulate matter from local industrial activities, even in active volcanic areas.<strong></strong></p>

The Impact of Phenological Gaps on Leaf Characteristics and Foliage Dynamics of an Understory Dwarf Bamboo, Sasa kurilensis.

Phenological gaps exert a significant influence on the growth of dwarf bamboos. However, how dwarf bamboos respond to and exploit these phenological gaps remain enigmatic. The light environment, soil nutrients, leaf morphology, maximum photosynthetic rate, foliage dynamics, and branching characteristics of Sasa kurilensis were examined under the canopies of Fagus crenata and Magnolia obovata. The goal was to elucidate the adaptive responses of S. kurilensis to phenological gaps in the forest understory. The findings suggest that phenological gaps under an M. obovata canopy augment the available biomass of S. kurilensis, enhancing leaf area, leaf thickness, and carbon content per unit area. However, these gaps do not appreciably influence the maximum photosynthetic rate, total leaf number, leaf lifespan, branch number, and average branch length. These findings underscore the significant impact of annually recurring phenological gaps on various aspects of S. kurilensis growth, such as its aboveground biomass, leaf morphology, and leaf biochemical characteristics. It appears that leaf morphology is a pivotal trait in the response of S. kurilensis to phenological gaps. Given the potential ubiquity of the influence of phenological gaps on dwarf bamboos across most deciduous broadleaf forests, this canopy phenomenon should not be overlooked.

Culm dynamics of dwarf bamboo (Sasa kurilensis Makino & Shibata) in relation to forest canopy conditions in beech forests

The dynamics of understorey dwarf bamboos are an important factor in forest dynamics. Although there have been a number of recent reports about the regeneration process after the simultaneous flowering and death of bamboos, the long-term dynamics of dwarf bamboos on the forest floor and outside the regeneration process (i.e., non-flowering state) are unclear. The present study aimed to investigate the long-term changes in Sasa kurilensis Makino & Shibata (Poaceae, Bambusoidae) populations in relation to the forest canopy and environmental conditions in the primeval beech forests of Shirakami-Sanchi World Heritage Area, Japan. Ten permanent plots (2 × 5 m) were established at three study sites (1 ha) in beech forests. Each site differed in forest structure. All S. kurilensis culms were censused from 2001 to 2019. The estimated maximum longevity of culms indicated that S. kurilensis culms can survive up to approximately 7000 days, nearly 20 years. The culm density and above-ground biomass varied widely amongst the study plots, and abrupt changes were observed in some plots affected by changes in the forest canopy conditions, such as gap formation. The relationship between canopy closure and culm density in 2001 showed an inverse proportional trend that weakened in 2019, indicating that S. kurilensis developed its population under closed canopies (dark conditions). More attention should be paid to such wide variations and unstable changes in understorey bamboo populations if the dynamics of these forests are to be better understood.

Disentangling the direct and indirect effects of canopy and understory vegetation on the foraging habitat selection of the brown bear Ursus arctos

Elucidating the factors affecting the foraging habitat selection of wildlife can further our understanding of the animal–habitat relationships and inform wildlife conservation and management. Canopy and understory vegetation may directly or indirectly affect the foraging habitat selection of carnivores through changes in habitat structure and prey availability, respectively; however, the relative importance of these two effects remains largely unknown. Dwarf bamboo Sasa kurilensis is a predominant understory plant that suppresses regeneration in the forests of northern Japan. The purpose of this study was to disentangle the direct and indirect effects of canopy forest type Larix kaempferi plantation versus natural mixed forest) and dwarf bamboo on foraging habitat selection of a large carnivore, the brown bear Ursus arctos. In the Shiretoko World Heritage, brown bears dig for cicada nymphs during summer. We evaluated the frequency of brown bear foraging on cicadas by investigating traces of digging for cicada nymphs. A structural equation model was used to statistically disentangle the direct and indirect effects of vegetation. Our results demonstrated that canopy and understory vegetation directly and indirectly affected foraging habitat selection of brown bears. Dwarf bamboo negatively affected cicada nymph density, which positively affected brown bear digging. This suggests that dwarf bamboo also had indirect negative effects on brown bears. Forest type had significant direct and indirect effects via change in cicada nymph density on foraging behavior in brown bears. Forestry managers in northern Japan, including the study site, try to remove dwarf bamboo for assisting natural regeneration. Removal of dwarf bamboo by scarification might not only promote natural regeneration, but also provide a beneficial foraging habitat for bears.

Lamproderma ovoideoechinulatum . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Lamproderma ovoideoechinulatum , a myxomycete which occurs on dead branches, leaves, stems, and twigs of angiosperms and gymnosperms, and on dead fronds of ferns. Some information on its interactions and habitats, economic impacts, intraspecific variation, dispersal and transmission and conservation status is given, along with details of its geographical distribution (NORTH AMERICA: Canada (British Columbia); ASIA: Japan; EUROPE: Austria, France, Germany, Italy, Norway, Poland, Spain, Switzerland, Ukraine) and associated organisms and substrata (Plantae: Alnus sp. (branch); Apiaceae indet. (stem); Athyrium filix-femina (frond, stem); Carex sp.; Epilobium angustifolium ; Fagus sylvatica (twig); Gramineae indet. [also as 'grasses']; Picea sp. [as 'spruce'] (leaf, stem); Plantae indet. (branch, stem); Rubus idaeus, R. ulmifolius, Rubus sp.; Salix purpurea (twig); Sasa kurilensis, Sasa sp.; Vaccinium myrtillus (twig); Protista: Didymium dubium ; Lamproderma sauteri, L. zonatum ; Meriderma carestiae ).

Regeneration process biased toward under-crown Sasa-lacking habitat of sparse Abies mariesii forest with dense undergrowth of dwarf bamboo on a snowy mountain, northern Japan

ABSTRACTIn sparse Abies mariesii forests with an undergrowth of dense dwarf bamboo (Sasa kurilensis) in subalpine areas of snowy mountains in northern Honshu, Japan, A. mariesii saplings are more abundant in Sasa-lacking patches under the crowns of A. mariesii canopy trees than in outside-crown areas densely covered with Sasa. To discuss the mechanism of such under-crown-biased regeneration, we examined the underlayer light conditions, population structure, seed dispersal, and the survival and growth of seedlings and saplings in four habitats with different canopy and undergrowth conditions, i.e. under-crown lacking Sasa (UCLS), under-crown with Sasa (UCWS), outside-crown lacking Sasa (OCLS), and outside-crown with Sasa (OCWS). Sapling banks were observed in all four habitats. The light condition in the UCLS was almost equivalent to or inferior to that in the OCWS. The survivorship of seedlings and saplings did not differ among the habitats. The increment of sapling trunk length in the UCLS was equivalent to that in the OCWS. These results indicate that the presence of A. mariesii canopy trees did not significantly improve the light condition, survival, or growth of A. mariesii seedlings and saplings. Instead, abundant seed supply under the crowns contributed to higher population densities and under-crown-biased regeneration. The existence of a sapling bank in the OCWS suggests the possibility of successful A. mariesii regeneration in this habitat even without the simultaneous death of Sasa. The dynamics of sparse A. mariesii forest may progress through shifting of the canopy and undergrowth conditions (e.g. UCLS to OCWS via OCLS).

Topographic Feature Analysis of Sasa kurilensis Expanding Part and Extraction of Potentially Easy to Expand Habitat at the Alpine Snow-meadow in the Taisetsu Mountains, Northern Japan

Topographic Feature Analysis of <i>Sasa kurilensis </i>Expanding Part and Extraction of Potentially Easy to Expand Habitat at the Alpine Snow-meadow in the Taisetsu Mountains, Northern Japan

Interactive effects of charcoal and earthworm activity increase bioavailable phosphorus in sub-boreal forest soils

The purpose of this study was to assess the effects of charcoal and earthworm presence in contrasting soil types of northern Japan using the biologically based phosphorus (BBP) extraction method, which employs a variety of plant P acquisition strategies. Using soils developed in serpentine and sedimentary parent materials, we tested the interactive effects of Eisenia japonica (Michaelsen) earthworms and 500 kg ha−1 of dwarf bamboo charcoal (Sasa kurilensis (Rupr.) Makino et Shibata) in a microcosm incubation that lasted four weeks. Soils were extracted in parallel after the incubation with the BBP method using 0.01 M CaCl2 (soluble P), 0.01 M citric acid (chelate-extractable P), 0.02 phosphatase enzyme units ml−1 (enzyme-extractable organic P), and 1.0 M HCl (mineral occluded P). Dwarf bamboo charcoal alone contained up to 444 mg total BBP kg−1 prior to application to soil microcosms. Treatment effects in soil microcosms were highest in sedimentary soil types and where charcoal was combined with earthworms (15.97 mg P kg−1 ± SE 1.23 total inorganic BBP). Recalcitrant inorganic P (HCl extracted) in combination treatments yielded the highest single inorganic BBP measure (12.41 mg kg−1 ± SE 1.11). Our findings suggest that charcoal, as a legacy of wildfire, and native earthworm activity may help stimulate cycling of recalcitrant inorganic BBP pools.

&amp;lt;i&amp;gt;In Vitro&amp;lt;/i&amp;gt; Bioassay of Allelopathy in Four Bamboo Species; &amp;lt;i&amp;gt;Bambusa multiplex, Phyllostachys bambusoides, P. nigra, Sasa kurilensis&amp;lt;/i&amp;gt;, Using Sandwich Method and Protoplast Co-Culture Method with Digital Image Analysis

Moderately strong allelopathic activities were found in four bamboo species, Bambusa multiplex cv. Houraichiku; Phyllostachys bambusoides cv. Madake; P. nigra cv. Hachiku; Sasa kurilensis cv. Chishimazasa, which are of different classification or of different ecological distributions, using the “Sandwich Method”, which assays the dried leaves on growth of lettuce seedlings. Only small difference of activity was found among the four bamboo species. In addition, “Protoplast Co-culture Method” for assay of allelopathy in a 50 μL liquid medium using a 96 well culture plate, was applied to the suspension cultures of the four bamboo species. Protoplasts were isolated from two-week cultured suspension cells of four bamboo species using Cellulase RS and Pectolyase Y-23 in 0.6 M mannitol. At low protoplast densities of bamboo, B. multiplex and P. bambusoides stimulated the recipient lettuce growth, i.e., non-spherically cell enlargement and cell divisions observed under an inverted microscope, while protoplasts of P. nigra and S. kurilensis were less stimulatory or inhibitory. Inhibitory effect of S. kurilensis was the strongest among four bamboo species. Furthermore, highly inhibitory effects of S. kurilensis protoplasts on yellow color accumulation of lettuce protoplasts were clearly observed by analysis of a scanned digital image of a 96-well culture plate. Differences and causes of the allelopathic activities were discussed comparing with other plant species studied using the same assay methods.

How does the longevity of Sasa kurilensis ramets respond to a light gradient? An analysis of ontogenetic changes to hydraulic resistance and carbon budget within a ramet

AbstractWe investigated how Sasa kurilensis ramet longevity differs under three light conditions. Ramet longevity is an important factor affecting the abundance of ramet populations and their biomass. The objectives of this study were to clarify: (1) whether ramet longevity varies spatially along a gradient of light conditions; (2) whether physiological functions, including water transport in culms, change with ontogenesis; (3) whether ramet longevity is associated with the most effective turnover for gaining a carbon profit within a ramet following a cost‐benefit model or is affected by other factors such as death caused by a decline in physiological function. We analyzed S. kurilensis ramet longevity, hydraulic resistance, photosynthetic rate, and carbon content. We then estimated the ramet carbon budget. The longevity of S. kurilensis ramets was 2.8–4.5 years in Beneath‐patch plots, 5.8–8.7 years in Edge‐patch plots, and 1.6–2.2 years in Open‐patch plots. Although leaf photosynthetic activity was stable, the instantaneous photosynthetic rate decreased during clear days in the open area. This may have been due to increased ramet hydraulic resistance. The rotation period of the most efficient carbon budget quantified by ecophysiological measurements was consistent with ramet longevity in Open‐patch (2 years) and Edge‐patch (5 years) sites. Meanwhile, the longevity of ramets grown under canopies was inconsistent with the cost‐benefit model rules for a carbon budget because the carbon gain was low throughout the ramet life span.

Degradation and recovery of an alpine plant community: experimental removal of an encroaching dwarf bamboo

The dwarf bamboo Sasa kurilensis has responded to recent climate change by expanding its distribution into alpine snow meadows in Japan. Tall, dense clonal patches of bamboo suppress alpine plant growth, alter ecosystem functioning, and reduce diversity. We aim to assess the ecological impacts of bamboo expansion and the effectiveness of bamboo control for restoring alpine vegetation and species diversity. We quantified the extent of bamboo expansion, its effects on an alpine ecosystem, and the recovery of species diversity by bamboo removal over 6 years in Daisetsuzan National Park, northern Japan. We established paired, experimental plots assigned to either removal or control treatments following an encroaching gradient from interior to terminal locations in a large bamboo patch. We monitored bamboo development and aboveground production, and its impact on soil moisture and species diversity to assess the recovery process of snow meadow species after its removal. In control plots, bamboo density consistently increased and accumulated biomass from year to year. In the removal treatment, bamboo culm density, height and biomass decreased through time at all locations. Furthermore, soil moisture increased in the removal plots and remained consistently higher than controls throughout the growing season. Dwarf bamboo strongly suppressed alpine plants and reduced species diversity. However, alpine snow meadow species rapidly recovered and diversity increased through time in the removal treatment. This study presents an effective management strategy for restoring alpine plant diversity impacted by bamboo expansion under global climate change.

Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan

Abstract. Forests play an important role in the terrestrial carbon balance, with most being in a carbon sequestration stage. The net carbon releases that occur result from forest disturbance, and windthrow is a typical disturbance event affecting the forest carbon balance in eastern Asia. The CO2 flux has been measured using the eddy covariance method in a deciduous broadleaf forest (Japanese white birch, Japanese oak, and castor aralia) in Hokkaido, where incidental damage by the strong Typhoon Songda in 2004 occurred. We also used the biometrical method to demonstrate the CO2 flux within the forest in detail. Damaged trees amounted to 40 % of all trees, and they remained on site where they were not extracted by forest management. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production were 1350, 975, and 375 g C m−2 yr−1 before the disturbance and 1262, 1359, and −97 g C m−2 yr−1 2 years after the disturbance, respectively. Before the disturbance, the forest was an evident carbon sink, and it subsequently transformed into a net carbon source. Because of increased light intensity at the forest floor, the leaf area index and biomass of the undergrowth (Sasa kurilensis and S. senanensis) increased by factors of 2.4 and 1.7, respectively, in 3 years subsequent to the disturbance. The photosynthesis of Sasa increased rapidly and contributed to the total GPP after the disturbance. The annual GPP only decreased by 6 % just after the disturbance. On the other hand, the annual Re increased by 39 % mainly because of the decomposition of residual coarse-wood debris. The carbon balance after the disturbance was controlled by the new growth and the decomposition of residues. The forest management, which resulted in the dead trees remaining at the study site, strongly affected the carbon balance over the years. When comparing the carbon uptake efficiency at the study site with that at others, including those with various kinds of disturbances, we emphasized the importance of forest management as well as disturbance type in the carbon balance.

Shade tolerance of temperate Asian bamboos: a harbinger of their naturalization in Pacific Northwest coniferous forests?

Bamboos native to temperate East Asian coniferous forests arrive with increasing frequency in the United States as horticultural imports, and some are becoming naturalized locally. Given the strong floristic and physiognomic similarities between East Asian and western North American coniferous forests, we asked whether these introduced bamboos could tolerate the varied light regimes within coniferous forests in their new range. Seven temperate Asian bamboos and one North American bamboo (Arundinaria gigantea) were grown within shade structures in an experimental garden; these structures reduced ambient light to three light levels (50, 70, 90 % shade) that occur routinely within coniferous forests in the Pacific Northwest. Species’ responses under these light levels were measured by their light response curves to photosynthesis, resource allocation to light or carbon harvesting centers inferred by CO2 response curves, and shifts amongst forms of leaf Chlorophyll. Bashania fargesii has lower chlorophyll content and photosynthetic rates under high shade (90 %) relative to other Asian species and to B. fargesii grown in 50 and 70 % shade. Bashania fargesii, Sasa kurilensis and A. gigantea also displayed lower photosynthetic rates under 90 % shade compared to plants grown in 50 and 70 % shade and lower electron transport capacity under 70 and 90 % shade compared to plants grown in 50 % shade. In contrast, Pleioblastus chino, Pleioblastus distichus, Pseudosasa japonica, Sasa palmata and Sasaella ramosa display strong tolerance of low light. Our results indicate these five Asian bamboos (and others yet to be introduced) could skirt a major environmental barrier to new species establishment in these North American forests. Measuring a species’ light response curve offers a reliable, rapid means to assess an immigrant species’ potential to tolerate forests’ varied light regimes.

Simulation of strip-gap arrangement in cedar plantations to regulate the light environment and competition between dwarf bamboo and beech seedlings

Summary We estimate a suitable strip-gap arrangement in Japanese cedar (Cryptomeria japonica) plantations to promote the growth of beech (Fagus crenata) seedlings and control dwarf bamboo (Sasa kurilensis) in mountainous areas using a hemispherical model and United States Geological Survey Digital Elevation Model (DEM). Clarification was also sought on whether the gap arrangement should be altered with topography and original stand structure. Nine modelled plantations were established by combining tree inventory and DEM data from three C.japonica plantations. We simulated spatial and temporal variations in photosynthetic photon flux density in stands 5 years after strip-gap creation under six scenarios for each modelled stand and integrated the light responses of F. crenata seedlings and S. kurikensis into the model. Finer strip-gap mosaics with gap width narrower than half the tree height inhibit the growth of S. kurikensis and provide a wider area suitable for F. crenata growth. Our simulation indicated a suitable strip-gap arrangement should be based on the stand structure but not necessarily on topography. However, it indicated that the possible range of practical gap arrangements changed with topography. The decision-support model for gap arrangement used in this study combined with DEM data provides flexible gap creation options adaptable to specific plantations in mountainous areas.

Deep Supercooling and Freezing Behaviors in the Leaf Blade and Leaf Sheath of a Cold Hardy Bamboo, Sasa kurilensis, Analyzed Using Cryomicroscopy

Deep Supercooling and Freezing Behaviors in the Leaf Blade and Leaf Sheath of a Cold Hardy Bamboo, Sasa kurilensis, Analyzed Using Cryomicroscopy

Lepidoderma carestianum . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Lepidoderma carestianum , a nivicolous myxomycete. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (Canada (Ontario), USA (Arizona, California, Colorado, Iowa, Kansas, Massachusetts, Michigan, New Hampshire, New Mexico, Washington), Japan, Russia (Chukotskyi Avtonomnyi okrug), Australia (New South Wales), New Zealand, Austria, Denmark, France, Italy, Norway, Poland, Russia (Leningradskaya oblast), Slovenia, Spain, Sweden, Switzerland, UK, and Ukraine), hosts ( Deschampsia cespitosa , Empetrum nigrum subsp. hermaphroditum , Graminae indet., Juncus trifidus , Nardus stricta , Plantae indet., Rubus idaeus , Sasa kurilensis , Taxus sp., Vaccinium myrtillus ), other substrata (soil), interactions and habitats.

A forest-structure-based analysis of rain flow into soil in a dense deciduous Betula ermanii forest with understory dwarf bamboo

The relationship between rain flow into the soil and forest structure was investigated in a dense deciduous Betula ermanii forest in northern Japan. The forest floor was covered with dwarf bamboo Sasa kurilensis. Observation was conducted from mid-July to late October in 1998. Leaf fall of Betula started in early September and ended in late October. Stemflow was proportional to rainfall and tree size [diameter at breast height (DBH)], and for the same rainfall, stemflow increased with leaf fall. On the contrary, throughfall decreased with leaf fall. Throughfall was intercepted also by Sasa in proportion to its leaf area. Multiple linear regression analysis revealed that stemflow and throughfall of Betula and Sasa were predictable as functions of rainfall and forest structural characteristics, such as DBH, tree density, and stand leaf mass. The rain interception by plants tended to decrease from summer to autumn, but the difference in the interception was about 2% between July (fully expanded leaves) and late October (lack of leaves). About 96 and 87% of rainfall reached the above- and below-Sasa layers, respectively. Thus, this study showed that understory Sasa is a major component of rain interception within the stand and that rain flow into the soil can be estimated by using rainfall and the forest structural parameters, such as DBH, tree density and stand leaf mass.

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.

Leaf litterfall and decomposition of different above- and belowground parts of birch (Betula ermanii) trees and dwarf bamboo (Sasa kurilensis) shrubs in a young secondary forest in Northern Japan

In many Japanese forests, the forest understory is largely dominated by dwarf bamboo (Sasa) species, which compete with overstory vegetation for soil nutrients. We studied the rate of leaf litterfall, and decomposition and mineralization of carbon (C) and nitrogen (N) from various components (leaf, root, wood, and rhizome) of overstory and understory vegetation in a young Betula ermanii forest from 2002 to 2004. Total litterfall was 377 g m−2 year−1, of which the overstory vegetation contributed about two thirds. A litter decomposition experiment conducted for 770 days indicated that mass loss of different litter components varied significantly, except for Sasa kurilensis wood and rhizome. Relative decomposition rates were significantly greater in the first growth period (June to October) than the dormant period (November to May) in most cases. Rainfall was the most important abiotic variable, explaining 75–80% of the variability in mass loss rates. Concentrations of ethanol soluble substances and N were significantly positively correlated (r=0.77 to 0.97, P<0.05) with mass loss at an early stage (41 days). The ratios of lignin/N and C/N were found to be negatively correlated with mass loss rates at all stages of litter decomposition. C stock loss was similar to that of mass loss, whereas N stock loss was slower, except for S. kurilensis fine root litter. The evergreen understory species S. kurilensis exhibited greater N use efficiency than B. ermanii, suggesting better competitive ability that might favor the production of a high biomass and invasion under tree species like B. ermanii.