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173 results on '"Hirobe, Muneto"'

10. Temporal and spatial dynamics of an old-growth beech forest in western Japan

Author

Ariya, Uyanga, Hamano, Ken-Ya, Makimoto, Takushi, Kinoshita, Shu, Akaji, Yasuaki, Miyazaki, Yuko, Hirobe, Muneto, and Sakamoto, Keiji

Abstract

Dendrochronological approaches enable us to understand forest stand dynamics by estimation of disturbance history and age structure. The present study was conducted in an old-growth beech forest in a forest reserve in western Japan. Increment cores were taken for tree ring analysis from all canopy trees in a 50 m × 130 m study plot. Radial growth release criteria were developed to identify significant growth releases in each tree ring series and to characterize the disturbance history of the study site. The age structure of the forest was indicative of continuous establishment by Fagus crenataand simultaneous establishment by Magnolia obovata. A variety of low-intensity disturbances were identified in each decade, especially after the 1900s, but the occurrence of high-intensity catastrophic disturbance was rare, and likely played an important role in maintaining species diversity in the existing forest canopy. The results also suggest that F. crenataregenerates gradually before and after both large- and small-scale disturbances, whereas M. obovataand Betula grossaregenerate only after large-scale catastrophic disturbances.

Published
2024
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44. Selective pollination by fungus gnats potentially functions as an alternative reproductive isolation among five Arisaema species.

Author

Matsumoto, Tetsuya K, Hirobe, Muneto, Sueyoshi, Masahiro, and Miyazaki, Yuko

Subjects
*MYCETOPHILIDAE, *FLOWERING of plants, *SPECIES, *ANGIOSPERMS, *CLIMATE change
Abstract

Background and Aims Interspecific difference in pollinators (pollinator isolation) is important for reproductive isolation in flowering plants. Species-specific pollination by fungus gnats has been discovered in several plant taxa, suggesting that they can contribute to reproductive isolation. Nevertheless, their contribution has not been studied in detail, partly because they are too small for field observations during flower visitation. To quantify their flower visitation, we used the genus Arisaema (Araceae) because the pitcher-like spathe of Arisaema can trap all floral visitors. Methods We evaluated floral visitor assemblage in an altitudinal gradient including five Arisaema species. We also examined interspecific differences in altitudinal distribution (geographic isolation) and flowering phenology (phenological isolation). To exclude the effect of interspecific differences in altitudinal distribution on floral visitor assemblage, we established ten experimental plots including the five Arisaema species in high- and low-altitude areas and collected floral visitors. We also collected floral visitors in three additional sites. Finally, we estimated the strength and contribution of these three reproductive barriers using a unified formula for reproductive isolation. Key Results Each Arisaema species selectively attracted different fungus gnats in the altitudinal gradient, experimental plots and additional sites. Altitudinal distribution and flowering phenology differed among the five Arisaema species, whereas the strength of geographic and phenological isolations were distinctly weaker than those in pollinator isolation. Nevertheless, the absolute contribution of pollinator isolation to total reproductive isolation was weaker than geographic and phenological isolations, because pollinator isolation functions after the two early-acting barriers in plant life history. Conclusions Our results suggest that selective pollination by fungus gnats potentially contributes to reproductive isolation. Since geographic and phenological isolations can be disrupted by habitat disturbance and interannual climate change, the strong and stable pollinator isolation might compensate for the weakened early-acting barriers as an alternative reproductive isolation among the five Arisaema species. [ABSTRACT FROM AUTHOR]

Published
2021
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46. A water acquisition strategy may regulate the biomass and distribution of winter forage species in cold Asian rangeland

Author

10233199, Tanaka‐Oda, Ayumi, Endo, Izuki, Ohte, Nobuhito, Eer, Deni, Yamanaka, Norikazu, Hirobe, Muneto, Nachinshonhor, G. U., Koyama, Asuka, Jambal, Sergelenkhuu, Katsuyama, Masanori, Nakamura, Takashi, Matsuo, Naoko, Jamsran, Undarmaa, Okuro, Toshiya, Yoshikawa, Ken, 10233199, Tanaka‐Oda, Ayumi, Endo, Izuki, Ohte, Nobuhito, Eer, Deni, Yamanaka, Norikazu, Hirobe, Muneto, Nachinshonhor, G. U., Koyama, Asuka, Jambal, Sergelenkhuu, Katsuyama, Masanori, Nakamura, Takashi, Matsuo, Naoko, Jamsran, Undarmaa, Okuro, Toshiya, and Yoshikawa, Ken

Abstract

Aboveground biomass is often restricted by water availability; therefore, water acquisition strategies have important roles in determining biomass volume and distribution under arid conditions. In cold Asian rangelands, the large tussock grass Achnatherum splendens is the most important forage for maintaining livestock under severe winter conditions. However, A. splendens distribution is restricted to the middle of the slopes of ephemeral streams, making it difficult to manage winter foraging. To understand the mechanisms behind the specific distribution and maintenance of a large A. splendens biomass under arid conditions, we established four typical vegetative plots along a riverside slope with different A. splendens density levels and elevations: river bottom with no A. splendens , riverbank with a large A. splendens community, upper slope with an isolated A. splendens community, and flat plain with no A. splendens . We measured the soil pH and electric conductivity (EC ) of the plots and investigated the vertical biomass and root distribution of A. splendens . We also investigated the water source for the A. splendens communities using isotope techniques. The soil pH was not different among plots, while the soil EC was significantly higher in the river bottom because of salt accumulation. However, low soil EC levels were found under the A. splendens communities. In the ground below the A. splendens communities, plant stems were buried deeply. The belowground biomass and buried stem depths decreased at the sites of the isolated A. splendens communities in the upper slope. The aboveground biomass of A. splendens increased as the stem burial depths and, therefore, the adventitious roots depths increased. The water source of A. splendens was estimated to be at a depth of more than 30 cm. Thus, A. splendens prefers a habitat with a low level of soil salinity and a high level of water availability, which may increase with the sand burial depth because of the increasin

Published
2018

47. A water acquisition strategy may regulate the biomass and distribution of winter forage species in cold Asian rangeland

Author

Tanaka‐Oda, Ayumi, primary, Endo, Izuki, additional, Ohte, Nobuhito, additional, Eer, Deni, additional, Yamanaka, Norikazu, additional, Hirobe, Muneto, additional, Nachinshonhor, G. U., additional, Koyama, Asuka, additional, Jambal, Sergelenkhuu, additional, Katsuyama, Masanori, additional, Nakamura, Takashi, additional, Matsuo, Naoko, additional, Jamsran, Undarmaa, additional, Okuro, Toshiya, additional, and Yoshikawa, Ken, additional

Published
2018
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50. Effects of fire-derived charcoal on soil properties and seedling regeneration in a recently burned Larix gmelinii/Pinus sylvestris forest

Author

Kobayashi, Makoto, Hirobe, Muneto, DeLuca, Thomas H., Bryanin, Semyon V., Procopchuk, Valentina F., and Koike, Takayoshi

Subjects
Charcoal, Regeneration, Forest fire, Phosphate, Russian Far East
Abstract

Purpose: Fire is a primary form of disturbance in boreal ecosystems. Charcoal is an important byproduct of forest fire and has been reported to have the potential to influence the plant community establishing after fire. To date, however, no study has effectively tested the relationship between charcoal and plant regeneration in the actual post-fire forests. To determine the contribution of charcoal to soil properties and plant regeneration after forest fires, we conducted in situ investigations concerning the relationship between charcoal and the plant-soil system. Materials and methods: We conducted a field investigation in a recently burnt Gmelin larch (Larix gmelinii)/Scots pine (Pinus sylvestris) forest in Russian Far East to investigate charcoal contents, pH water contents, and nutrient availability in soil together with the regeneration of larch and pine seedlings. Results and discussion: Positive correlations were found between charcoal contents and soil pH, water contents, and available P contents. Additionally, charcoal contents and number of pine seedlings were positively correlated. There was, however, no significant relationship between charcoal content and extractable NH4+ content or the number of larch seedlings. These results suggest that while charcoal influences are somewhat obscure in the field, charcoal significantly contributes to the amelioration of water and nutrient availability together with the success of regeneration of pine seedling. Conclusion: Charcoal produced during fire events in Gmelin larch and Scots pine forests of eastern Russia has a modest influence on soil properties, but has the potential to improve regeneration in these fire prone ecosystems.

Published
2011

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