Dwarf Bamboo Research Articles

Synergistic Effect of Dwarf Bamboo Flowering and Wild Boar Rooting on Forest Regeneration

Sasa spp., monocarpic dwarf bamboos, are known to form recalcitrant understories, lower species diversity, and hinder forest development. Sasa borealis distributed throughout Korea showed a phenomenon of synchronized dieback after large-scale synchronized flowering nationwide around 2015. Therefore, we conducted this study to take advantage of the rare event and add prevailing activity of wild boars and culm removal to elucidate whether they promote the regeneration of a long-term suppressed forest. We set permanent plots in forests with different understory types, and tracked the vegetation change in 5 years with respect to species composition, tree regeneration, and S. borealis reestablishment. This study focused on comparison between plots established after mass flowering. In flowering stands, we found the species diversity increased significantly with increase in species evenness, but not with recruitment of new species. Furthermore, the seeds of mass-produced bamboo germinated, and the seedling abundance was found to increase considerably. In stands rooted by wild boar, species diversity increased through the recruitment of new species, including tree species. It increased the abundance of shrub and perennial herbs, while it suppressed the reestablishment of S. borealis. Although rooting effect was independently significant regardless of flowering, the synergistic effect of rooting and flowering on forest regeneration was outstanding. Wild boar seemed to function as a remover of dead culms and a breaker of remaining underground mats as well as a seed disperser. Consequently, the species composition became similar to the reference stands. However, culm cutting caused negative effects by facilitating S. borealis to re-occupy or resprout. Overall, as the wild boar population increases, the positive effect can be expected to enhance. At landscape scale, considering several factors such as flowering and non-flowering, and population size of wild boar, the long-term suppressed forests by S. borealis are projected to regenerate with mosaic forests.

Dynamic study of the lead (Pb) tolerance and accumulation characteristics of new dwarf bamboo in Pb-contaminated soil

Dwarf bamboo is a woody plant with potential for use in the remediation of Pb-contaminated soil. Due to its clonal growth habit, there are two keys to its application for continuous soil Pb remediation: 1) its ability to form shoots and grow into new bamboo normally under Pb stress and 2) the Pb tolerance and accumulation characteristics of this new bamboo. Here, 5 species of dwarf bamboo were treated with 2 levels of soil Pb stress (0 and 1500 mg kg−1). In the roots of 3 of the species (Sasa argenteostriata, Sasaella glabra, and Indocalamus decorus), Pb tended to be distributed along the cell wall and transported to vacuoles. In the other 2 species (Sasa auricoma and Sasa fortunei), Pb was arranged linearly along the cell wall. Under Pb treatment, the new bamboo of all species showed gradual physiological adaptation to Pb stress. Correlations of the net photosynthetic rate, superoxide dismutase activity, and free proline levels with Pb content in new leaves in November were all higher than those in July, though that of malondialdehyde content decreased, suggesting that new dwarf bamboo exhibits good soil Pb stress tolerance. Sasa argenteostriata and Indocalamus decorus consistently maintained higher antioxidant enzyme activities and free proline levels than the other species under Pb treatment, and the total biomass per pot of the new bamboo decreased the least compared to that in the Pb-free treatment for these two species. Therefore, these bamboo species may be used in the long-term continuous remediation of Pb-contaminated soil.

Effect of Suppression Treatment on Dwarf Bamboo under the Canopy Using Weeding and Herbicide:

Effect of Suppression Treatment on Dwarf Bamboo under the Canopy Using Weeding and Herbicide:

Survival of young, dense Betula ermanii stands after wildfire at top soil removal sites

Abstract A forest fire in a cool-temperate broadleaved forest in northern Japan, from 26 May to 19 June 2019, provided an opportunity to examine the post-fire dynamics of young, dense birch (Betula ermanii Cham.) stands that had previously undergone top soil removal through soil scarification. To characterize the post-fire responses (survival and resprouting) of birch trees, we set up two plots, 6 months after the fire. We investigated the trunk diameter at breast height and burn marks on the trunks (scorch height and bole charring percentage) of all B. ermanii trees in both plots. Survival and resprouting of each tree were monitored over a 10-month period (6 and 16 months after the fire). To quantify post-fire vegetation recovery of the forest floor, we manually mapped the dominant understory plant, dwarf bamboo (i.e. Sasa kurilensis (Rupr.) Makino et Shibata), from orthomosaic images obtained using an unmanned aircraft vehicle, and estimated the recovery rate in the second year after the fire. Additionally, the seedlings of woody species were counted in both plots. A logistic generalized linear model revealed that the size-dependent survival rates of the plants in each plots were similar in the first year after fire. All B. ermanii trees died without resprouting in the second year after the fire, indicating the lethal effects of fire on young birch trees in top soil removal sites. Moreover, a high recovery rate of dwarf bamboo over 2 years in both plots and limited woody seedling establishment of woody plants suggest that the fire resulted in the regeneration failure of young stands in the top soil removal sites. Based on these findings, we suggest that the vulnerability of young trees can lead to the rapid change in vegetation from young forest to dense dwarf bamboo cover after a fire.

The protective effect of dwarf bamboo on broad-leaved seedlings against deer browsing

The forest understory is often densely covered by dwarf bamboo Sasa spp. in Hokkaido, northern Japan. Dwarf bamboo is an important winter forage for sika deer Cervus nippon, and dwarf bamboo inhibits forest regeneration by preventing seedling establishment. Although percentages of browsed seedlings are a useful index of deer browsing pressure, dwarf bamboo is also expected to affect browsing on seedlings by altering physical accessibility to seedlings. We hypothesized that the relationship between seedling height and browsing incidence depends on the coverage of dwarf bamboo because smaller seedlings were protected by dwarf bamboo. The incidence of browsing was recorded for broad-leaved seedlings ≥ 0.2 m in height and < 1 cm in diameter at breast height in 19 plots (40–200 m2 each) located in natural forests. Coverage of dwarf bamboo varied from 3% to 74%, except for one plot where dwarf bamboo was absent. The mean height of the dwarf bamboo in each plot was 0.44–1.17 m. The product of seedling height and coverage of dwarf bamboo was selected as an explanatory variable in the generalized linear mixed model for the incidence of browsing on each seedling. This suggests that smaller seedlings were protected by dwarf bamboo and browsing incidence is low for smaller seedlings within plots with high coverage of dwarf bamboo. This can be an example of associational defense against deer. The probability of browsing incidence was low for seedlings 0.2–0.5 m tall in sites with dense dwarf bamboo, while no significant differences were detected between seedlings 0.5–0.8 m tall and those ≥ 0.8 m. Even though seedlings under dwarf bamboo cover tend to escape from deer browsing, dwarf bamboo directly affects seedling survival and growth negatively. Therefore, it is necessary to manage both the deer population and dwarf bamboo to enable forest regeneration. The percentages of seedlings with browsing incidence on seedlings ≥ 0.5 m tall can approximate the browsing level and is useful for management decisions.

Timing of forest fine root production advances with reduced snow cover in northern Japan: implications for climate-induced change in understory and overstory competition

To investigate the effect of reduced snow cover on fine root dynamics in a cool-temperate forest in northern Japan because of decreases in snowfall at high latitudes due to global warming, we monitored root length, production, and mortality before and after snow removal with an in-ground root scanner. We measured root dynamics of both overstory deciduous oak (Quercus crispula) and understory evergreen dwarf bamboo (Sasa nipponica), the two major species in the forest. Snow removal advanced the timing of peak root production by a month both in total and in Sasa, but not in oak. There was a significant interaction between snow removal and plant form on root production; this indicates that enhanced Sasa root production following snow removal might increase its ability to compete with oak. In contrast, snow removal did not enhance root mortality, suggesting that the roots of these species tolerate soil freezing. The earlier snow disappearance in the snow removal plot expanded the growing season in Sasa. We speculate that this change in the understory environment would advance the timing of root production by Sasa by extending the photosynthetic period in spring. We propose that different responses of root production to reduced snow cover between the two species would change the competitive interactions of overstory and understory vegetation, influencing net primary production and biogeochemistry (e.g., carbon and nitrogen cycles) in the forest ecosystem.

Spatial Evaluation of Greenhouse Gas Fluxes in a Sasa (Dwarf Bamboo) Invaded Wetland Ecosystem in Central Hokkaido, Japan

To evaluate the effect of vegetation change on greenhouse gas (GHG) budget from a wetland ecosystem, the CO2, CH4 and N2O budgets from whole area (21.5 ha) of the Bibai Wetland, where dwarf bamboo (Sasa) or Ilex has invaded into original Sphagnum dominated vegetation, located in Hokkaido, Japan were estimated. The original Sphagnum-dominated vegetation was changed from a sink to a source of CO2 by invasion of short-Sasa (50 cm &gt; height), while the invasion of tall-Sasa (50 cm &lt; height &lt; 150 cm) or Ilex increased CO2 uptake. Annual CH4 emission was decreased by the invasion of Sasa or Ilex. The annual N2O emission was slightly increased by invasion of Ilex only. These GHG budgets were correlated with the environmental factors related to the water table depth. The distribution of vegetation and environmental factors was estimated from satellite image bands, and the GHG budget of the entire wetland was estimated. The whole wetland area was considered to be a sink for GHG (−113 Mg CO2-eq y−1) and CO2 uptake by tall-Sasa occupied 71% of the GHG budget. The vegetation change due to the lowering of the water table depth currently increases the rate of carbon accumulation in the ecosystem by about 5 times.

Gross primary production of dwarf bamboo, Sasa senanensis, in a mature beech forest with a substantial gap-mosaic structure.

Forest understory plays an important role in the gross primary production (GPP) of some forest ecosystems. However, differences in understory GPP caused by obviously different overstory canopy structure have not been taken into consideration in previous studies, thus potentially over- or underestimating understory GPP. To estimate the understory GPP more accurately, we separated a forest into "canopy area", with closed-overstory canopy, and "gap area", with open-overstory canopy. The study was conducted in a mature deciduous forest dominated by beech and with an understory dominated by dwarf bamboo, Sasa senanensis. We measured S. senanensis GPP at the community scale (GPPSasa-community) using a static chamber system that covered the aboveground part of the plants and then upscaled it to the ecosystem scale (GPPSasa-ecosystem) by considering the proportions of canopy and gap areas within the forest. GPPSasa-community was 192g C m-2year-1 in the canopy area and 699g C m-2year-1 in the gap area. The large difference likely occurred because the photosynthetic ability and biomass of the S. senanensis community differed strongly between the two areas. The seasonal dynamics of GPPSasa-community also differed between the areas. The 10-day cumulative GPPSasa-community peaked from July to August in the gap area, whereas there was no clear peak of GPPSasa-community in the canopy area. Multiple linear regressions showed that light intensity and biomass were significant predictors of GPPSasa-community in the canopy area, whereas air temperature and biomass were significant predictors of GPPSasa-community in the gap area. GPPSasa-ecosystem during growing season in 2019 was 3.74 t C ha-1year-1, which contributed between 16.37 and 19.85% of the entire forest ecosystem GPP. This study highlights the need to consider differences in overstory structure for the accurate estimation of understory GPP.

Physiological resistance of Sasa argenteostriata (Regel) E.G. Camus in response to high-concentration soil Pb stress

Dwarf bamboo Sasa argenteostriata (Regel) E.G. Camus has previously been considered as potential plant for metal phytoremediation. However, the dynamic responses and correlations among physiological resistances to high-concentration Pb exposure have not been described to date. This study conducted four Pb treatments (0, 1500, 3000, and 4500 mg kg–1) to examine the physiological resistance responses at days 7, 14, and 21. The findings showed that S. argenteostriata can regulate both the enzymatic system and the nonenzymatic system to synergistically overcome Pb damage. In addition, a significant positive correlation was found between enzymes and nonenzymatic substances, which were particularly apparent with regard to the superoxide dismutase (SOD) activities with phytochelatins (PCs) levels, peroxidase (POD), and glutathione reductase (GR) activities with glutathione (GSH) levels, as well as catalase (CAT) and ascorbate peroxidase (APX) activities with soluble protein (SP) levels. Furthermore, Pb concentration was the main factor that induced the physiological responses of S. argenteostriata to Pb stress. The antioxidant enzyme system and the AsA–GSH cycle were dominant resistance mechanisms under 1500 mg kg–1 Pb. AsA–GSH cycle and plant cell chelation were dominant resistance mechanisms under 3000 mg kg–1 Pb. Antioxidant enzymes and plant cell chelation were dominant resistance mechanisms under 4500 mg kg–1 Pb. This study provides comprehensive evidence regarding how both enzymatic and nonenzymatic systems of S. argenteostriata cooperate to alleviate the high-concentration soil Pb stress. The results highlight the environmental remediation potential of this species for Pb-contaminated media.

Dynamics of dwarf bamboo populations and tree regeneration over 40 years in a clear-cut beech forest: effects of advance weeding and herbicide application

ABSTRACT We explored the dynamics of dwarf bamboo populations in a beech forest 11 years before and 30 years after clear-cutting. Repeated weeding or herbicide application (sodium chlorate) was used experimentally to reduce or eliminate dwarf bamboo prior to clear-cutting. At the beginning of the study, the understory comprised dense populations of two Sasa species, the dominant S. palmata and the less common S. kurilensis. Both weeding and herbicide application rapidly reduced the cover of S. palmata, but it began to recover prior to clear-cutting and soon exceeded initial cover values. Both weeding and herbicide application reduced the cover of S. kurilensis to near-negligible levels; the cover increased slowly after clear-cutting but remained below initial levels. Weeding or herbicide application resulted in different patterns with respect to height; height decreased rapidly in response to weeding, whereas herbicide application had more gradual effects. Height began to increase after clear-cutting, and S. palmata exceeded its initial height, reaching 1.5–2.0 m in the 10–15 years following clear-cutting. No tree recruits were found in sites where dwarf bamboo was left unmanaged. Weeding and herbicide application facilitated recruitment of Betula ermanii after clear-cutting, but recruits of Fagus crenata, which originally dominated the forest canopy, remained scarce or non-existent at 30 years after clear-cutting. We postulate that natural regeneration of Fagus is nearly impossible following clear-cutting in temperate beech forests in Japan with dense undergrowth of Sasa, even with advance measures to reduce or eliminate Sasa.

Demography and productivity during the recovery time sequence of a wild edible bamboo after large-scale anthropogenic disturbance.

Anthropogenic disturbances in forest management practices can affect wild edible plants. Soil scarification is a large-scale disturbance that may cause long-term reduction in productivity of edible dwarf bamboo, Sasa kurilensis, in northern Japan. For their effective and sustainable use, we need to understand the recovery process after such disturbances. At 14 study sites in the Teshio Experimental Forest of Hokkaido University where soil scarification had been conducted between 2 and 44 years prior, the number and stem diameter of old and young (newly emerged, edible) culms was recorded. At sites that were within 11 years of soil scarification, the proportion of old culms (<11%) was lower than in the control area where soil scarification had never been conducted. At sites where more than 15 years had passed since soil scarification, the relative number of old culms was nearly equal to that in control area. Additionally, the number of young culms increased with an increasing number of old culms. These results suggest that recovery of productivity (in term of number) of edible culms may take a few decades. In contrast, the culm diameter of young culms increased linearly with time since soil scarification, but the 95% confidence interval in this relationship suggests that dwarf bamboo can produce thick edible culms soon after soil scarification. These findings will provide useful insights into how to obtain high quality bamboo culms following anthropogenic disturbances in future.

Biomass allocation strategies and Pb-enrichment characteristics of six dwarf bamboos under soil Pb stress

Dwarf bamboos are clonal plants with potential applications in the remediation of heavy metal-polluted soils, although their pollution adaptation strategies are unknown. This study examined the biomass allocation strategies and lead (Pb) enrichment characteristics of various dwarf bamboo tissues by the end of the growing season and explored their potential for phytoremediation of Pb stress in the soils. Six dwarf bamboo genotypes were treated with three levels (0, 300, and 1500 mg kg–1) of soil Pb stress. The majority of the bamboos adopted two biomass allocation strategies to adapt to Pb stress, namely, “reducing biomass allocation into new bamboo growth” and “increasing/stabilizing biomass allocation into rhizomes”. Pb accumulation was highest in the roots, rhizomes, and old stems and showed the following trend: rhizomes/old stems> new roots/old roots> old leaves> new leaves> new stems among various tissues. Moreover, the six bamboos used three different Pb-enrichment strategies, as follows: (i) “rhizome domination and old stem synergy” (Sasaella glabra (Nakai) f. albo-striata Muroi, Sasa auricoma (Mitford) E.G. Camus, Sasa fortunei (Van Houtte) Fiori, and Shibataea lanceifolia C.H. Hu); (ii) “old stem domination and rhizome synergy” (Indocalamus decorus Q.H. Dai); and (iii) “old stem domination and new root synergy” (Sasa argenteostriata (Regel) E.G. Camus). In Pb-contaminated soils, genotypes with TFs greater than 1 were Sasa fortunei (Van Houtte) Fiori, Sasa argenteostriata (Regel) E.G. Camus, and Indocalamus decorus Q.H. Dai; in addition, only S. argenteostriata had BCF values greater than 1. Furthermore, this study provides the first evidence that S. argenteostriata can extract 0.22 and 0.58 mgplant−1 of Pb ions in soil polluted with 300 and 1500 mg kg−1 Pb, respectively. S. argenteostriata showed the greatest potential for phytoremediation among the bamboo genotypes in both Pb-contaminated urban and mining sites.

Sustained enhancement of productivity of edible culms of Sasa kurilenses in response to repeated annual human harvesting in a northern forest in Japan

ABSTRACT Sasa kurilensis is a popular wild edible bamboo in Japan. Productivity (density) of edible culms can be enhanced by human harvesting, but we know little about how long the enhanced productivity is sustained after repeated annual harvesting. Here, demography and productivity of this edible bamboo were examined in field experiments conducted following experimental harvesting of edible bamboo culms for three years. Compared to the productivity of wild edible bamboo culms in the control plots, which were maintained with no human disturbance, productivity in the harvest-treatment plots (harvest conducted annually) was always greater in years following harvesting. In addition, food quality tests for boiled, edible bamboo culms collected from both harvest-treatment and control plots showed that there was little effect of harvesting on food quality of edible bamboo culms but that harvesting might degrade the favorability of food texture of boiled edible bamboo culms. Subsequent surveys demonstrated that the enhanced productivity may occur independently of demography (density) of old culms and that the enhanced productivity effect disappeared two years after the harvest treatment was stopped. These results indicate that repeated, annual harvesting is necessary to promote productivity of edible bamboo culms. These interesting but counterintuitive results can be explained by over-compensatory growth by dwarf bamboo, which respond by producing new photosynthetic organs to compensate for tissue loss by human harvesting. Thus, effective induction of compensatory growth may be a key factor in increasing the production of wild edible plants.

Effect of snow removal on the fine root biomass, dynamics, and carbon and nitrogen concentrations of oak and dwarf bamboo, Sasa in eastern Hokkaido, Japan

ABSTRACT Fine root is a significant component in carbon (C) and nitrogen (N) dynamics in temperate forests. Winter processes affect plant growth and nutrient concentration, however, the effect of reduced snowpack on fine root remains unclear. Here, we conducted snow removal manipulation and investigated the fine root biomass and necromass, dynamics (production, mortality and disappearance) and the C and N concentrations of Quercus crispula (oak) and Sasa nipponica (Sasa), in mineral topsoil (0–10 cm) throughout 1 year. The effect of snow removal on the fine root biomass and necromass was insignificant. The effect of snow removal on the production, mortality and disappearance of fine root, and on total C and N concentrations of fine root biomass and necromass were insignificant. The fine root biomass of oak was significantly greater than that of Sasa, although the fine root necromass of Sasa was significantly greater than that of oak. Fine root necromass showed clear seasonal change, although a seasonal change of fine root biomass was unclear. Total C concentration in the fine root biomass and necromass of oak was significantly higher than that of Sasa. Total N concentration in the fine root necromass in May 2015, when after the snow removal, of Sasa was significantly higher than that of oak, in both snow removal and control plots. Our results showed that the fine root necromass of Sasa supplies more N than that of oak in spring, regardless of snowpack depth.

The growth and mortality of Pleioblastus pygmaeus under different light availability

Pleioblastus pygmaeus (Miq.) Nakai, as a dwarf bamboo, providing a high ornamental value in landscaping. Furthermore its well-developed and intricate root system lends its use for soil consolidation and slope protection. A pot experiment was performed to study the impact of different light intensity on the growth characteristics of P. pygmaeus seedlings. The light intensity was controlled by punching circular holes with different diameters in center of the plates cover the pots. The illuminance percentages of the pore diameter area to the inner diameter area of the pot in each treatment were 1.29% (A), 5.16% (B), 11.62% (C), 20.66% (D), 32.28% (E), and 100% (F). The average illumination intensity under treatment A, B, C, D and E is 3.87%, 11.25%, 20.25%, 38.76% and 60.70% of control F (100% of full sunlight), respectively. The results showed that the light intensity is a key factor influencing P. pygmaeus seedlings’ growth and mortality. Seedlings died when light is lower than 38.76%. As light intensity decreased, the mortality increased and the number of culms and total rhizomes, leaf-, aboveground- and underground-biomass significantly decreased, and the gap between the treatments and control significantly increased over the nine month growing period. The generalized additive model (GAM) explained the influence of illuminance and investigation time and indicated a lower determination coefficient on culm height, culm diameter, total rhizome length and total rhizome diameter compared with number of culms, number of total rhizomes and biomass. The diameter of culms showed a decreasing trend during the experiment while their lengths increased even under A treatment (3.87% of full sunlight), suggesting that nonstructural carbohydrates stored prior to the experiment was used for culm height growth under light/carbon limitation. In the case of the leaves, their growth was significantly inhibited under low light intensity (3.87–60.70% of full sunlight) as they are the primary component of the plant’s photosynthetic apparatus. As suppressed leaves could not independently provide enough carbon to the plant, P. pygmaeus seedlings adjust their plasticity to slow down rhizome growth, shoot emergence and biomass accumulation, eventually resulting in “Carbon starvation” and increased mortality. This study provides insights into how dwarf bamboos balance growth and survival under low light availability.

Diets of sika deer invading Mt Yatsugatake and the Japanese South Alps in the alpine zone of central Japan

Sika deer Cervus nippon populations have been increasing on the Japanese archipelago. Their range is expanding to include the alpine zone in central Japan, where they stay during summer before descending to the lower areas during winter. No studies on dietary habits of alpine deer in mainland Japan have been conducted. This study assessed the composition of sika deer diets and compared nutritional quality between the low montane, subalpine and alpine zones. We analyzed sika deer fecal samples from Mt Yatsugatake (YT) and the Japanese South Alps (SA). In the lower mountain in YT, dwarf bamboo comprised 40–55% of the plant compositions in fecal samples, whereas dicots were mostly found in SA samples. In subalpine zones in YT, grasses are an important food item, comprising about 50% of the samples. In SA, monocots (10–20%) and dicots (10–20%) were both prevalent. In the alpine zone of both YT and SA, grasses were present the fecal samples (50% and 10–20%, respectively). Crude protein contents were higher at higher zones (15–20%) than at lower zones (8–12%) in both study areas.

Effect of root litter addition on nitrogen mineralization rate under laboratory low‐temperature conditions in soil from a Japanese northern hardwood forest

AbstractSoil freeze–thaw can alter the soil nitrogen (N) mineralization rate by increasing root litter. However, the mechanism remains unclear. We compared the effect of adding root litter from two plant species on soil production rate and soil production rate under low‐temperature conditions in laboratory incubation. Root litter of oak (Quercus crispula) or dwarf bamboo, Sasa (Sasa nipponica) was added to soil and incubated under nonfrost and soil freeze–thaw treatments. We monitored temporal change of net/gross production rate and production rate throughout the soil frost period and the following melting period. We measured dissolved organic N (DON) in root litter leachate under the two temperature treatments. The soil N mineralization with Sasa root litter was higher than that with oak root litter in the two temperature treatments. The DON in root litter leachate of Sasa was larger than that of oak. The effect of root litter addition on net production rate was larger than that on net production rate. The higher net production rate of soil with Sasa was considered to be caused by higher DON in leachate from root litter of Sasa. The higher inducement of N mineralization of Sasa root litter than oak root litter was related to quantity of organic N in the root litter leachate.

Effects of declining understory vegetation on leaf litter decomposition in a Japanese cool-temperate forest

ABSTRACT Understory vegetation, dominated by dwarf bamboo (Sasa spp.) in Japan, has been damaged by an overabundance of deer. Declining Sasa density may induce a decrease in litter decomposition due to the changes in soil environments. The effect of the environmental changes may also differ among litter from differenttree species. The objective of this study was to examine effects of declining Sasa density on litter decomposition in a cool-temperate mixed forest, with a focus on the effects of environmental factors and soil mesofauna on different litter species. The decomposition of three litter species was evaluated using litter bags with two different mesh sizes to consider different litter decomposability and control the accessibility of soil mesofauna. With decreasing Sasa density, soil water content increased whereas the number of soil mesofauna decreased. Litter mass loss decreased with declining Sasa density. Soil water content was negatively correlated with litter mass loss in the smaller mesh. Additionally, negative effects of Sasa degradation on litter decomposition did not change with litter species, but these effects changed among mesh sizes, suggesting that the effects of the decomposer community on litter decomposition changed with environmental conditions induced bySasadegradation. Complex interaction between decomposer communities and local environmental factors should be studied in further studies with longer periods over a wide range of areas.

Evaluation of carbon mineralization and structural alterations of organic carbon in high-moor peat soils during incubation

The quantity and quality of soil organic matter (SOM) in the wetlands and peatlands are important for evaluating of the effects of environmental changes. This study’s aim was to evaluate the change in the chemical properties of SOM and dissolved organic matter (DOM) during a constant temperature incubation of high-moor peat soil under two types of vegetation. Incubation of high-moor peat soils collected from marsh vegetation and dwarf bamboo was conducted for 108 days at each temperature of 25 °C and 35 °C. The chemical properties of alkaline extract and DOM in soil samples during incubation were analyzed by tetramethylammonium hydroxide thermochemolysis-gas chromatography-mass spectrometry (TMAH-GC/MS) and fluorescence analysis. The cumulative CO2 emission from peat under dwarf bamboo was higher than that of peat under marsh vegetation. During incubation at 35 °C, plant and microbial residues in DOM extracted from dwarf bamboo soil were increased significantly at the early stages of culture. On the other hand, the components of DOM in the marsh vegetation soil sample did not significantly change between incubation at each temperature. The fluorescence spectra showed that protein-like fluorescent DOM contained in dwarf bamboo soil is consumed by microorganisms, which promotes leaching of humic-like fluorescent DOM and carbon mineralization during the incubation period at a higher temperature. Compared with marsh vegetation soil, the DOM in dwarf bamboo soil is susceptible to temperature rises and can be a larger source of CO2 emissions. This study shows that evaluation of DOM properties in soil could be useful to assess the effect of climate change on soil environment.

Spatial genet dynamics of a dwarf bamboo: Clonal expansion into shaded forest understory contributes to regeneration after an episodic die‐off

AbstractThe ability of clonal plants to spread horizontally and to share resources within genets has long been considered advantageous in spatially heterogeneous environments, yet our understanding of how such traits relate to its widespread success and dominance is still limited. Using a dwarf bamboo, Sasa kurilensis, that often dominates cool‐temperate forest understorys, we investigated how population recovery over 20 years after an episodic die‐off may be augmented by clonal expansion via rhizomes. Previous analyses on genet demography using 9‐m2 plots showed that more productive genets were more likely to survive, spread laterally, and replace less productive ones. In this study, we examined whether the recovery of biomass in lower light microsites, where biomass recovery was initially slower, was supported by the spread of productive genets at larger scales, from surrounding higher‐light microsites. We found that the biomass recovery in lower‐light plots was more supported by genets that spread clonally into the plots. Such genets that spread from outside plots produced larger culms than those that had originally germinated there. Whereas genets that contributed much to the biomass of the low‐light plots spread extensively from higher‐light microsites, the spatial extent of genets that originally germinated in these plots was quite limited, so that the patterns of clonal expansion appeared to be unidirectional along the light gradient. Our findings suggest that clonal expansion of productive genets from higher‐light into shaded microsites may be important for S. kurilensis to proliferate across heterogeneous light environments.