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Ryuji Ichihashi Last modified date:2021.06.24

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Academic Degree
Country of degree conferring institution (Overseas)
Field of Specialization
plant ecology, forest ecology
ORCID(Open Researcher and Contributor ID)
Total Priod of education and research career in the foreign country
Research Interests
  • Water-use characteristics of trees, lianas and bamboos, and effects of vegetation characteristics on forest water dynamics
    keyword : hydraulic structure, transpiration, growth form, liana, bamboo,
  • Basic ecology of forest lianas.

    keyword : biomass allocation, growth, stem turnover, host-dependent support strategy
Academic Activities
1. Growth characteristics of forest lianas.
1. Ryuji Ichihashi, Hikaru Komatsu, Tomonori Kume, Yoshinori Shinohara, Kenji Tsuruta, Kyoichi Otsuki, Effects of thinning on canopy transpiration of a dense Moso bamboo stand in western Japan, Journal of Forest Research, 10.1080/13416979.2019.1647592, 24, 285-291, 2019.09.
2. Ryuji Ichihashi, Chen Wei Chiu, Hikaru Komatsu, Tomonori Kume, Yoshinori Shinohara, Makiko Tateishi, Kenji Tsuruta, Kyoichi Otsuki, Contribution of lianas to community-level canopy transpiration in a warm-temperate forest, Functional Ecology, 10.1111/1365-2435.12881, 31, 9, 1690-1699, 2017.09, Lianas (woody climbers) have a greater amount of leaves relative to basal area or standing biomass than trees, and very wide vessels that permit efficient water transport. These features suggest that lianas possibly consume proportionally more water through transpiration than trees. Despite their potential importance, researchers have made only limited attempts to evaluate effects of lianas on forest water dynamics. We conducted sap flow measurements for 1 year using a thermal dissipation method for four species each of lianas and trees in a liana-rich, warm-temperate forest in Japan and estimated the contribution of lianas to stand canopy transpiration. Based on a calibration measuring water uptake rates from cut-stem ends, the actual sap flux (Fd) in liana stems was several times greater than those estimated from the original calibration provided for the method. In the field, lianas showed an average of 2–4 times greater Fd than trees throughout the year. Except for this difference, diurnal and seasonal patterns of relative changes of Fd were similar in both groups. The whole-plant transpiration (Qt) of sample plants was exponentially related to basal diameter for both lianas and trees; Qt of lianas increased more steeply with basal diameter than that of trees. By extrapolating the relationships between Qt and basal diameter to the inventory data of the study plot, we estimated that lianas contributed 12·8% to the annual stand canopy transpiration while comprising 2·3% of stand basal area, which probably reflected the top-heavy architecture of lianas. Our results indicate that the contribution of lianas to forest water dynamics may be several times greater than their contribution to forest basal area. This implies that a slight increase of liana abundance might have greater effects on water dynamics and, through competitions with trees for limited water, the carbon sequestration capacity of forests than expected from the increase in basal area. This study underlines the necessity of evaluating the relative importance of lianas to forest water dynamics in forests world-wide. A lay summary is available for this article..
3. Ryuji Ichihashi, Masaki Tateno, Biomass allocation and long-term growth patterns of temperate lianas in comparison with trees, New Phytologist, 10.1111/nph.13391, 207, 3, 604-612, 2015.08, The host-dependent support habit of lianas is generally interpreted as a strategy designed to reduce resource investment in mechanical tissues; this allows preferential allocation to leaf and stem extension, thereby enhancing productivity and competitive abilities. However, this hypothesis has not been rigorously tested. We examined the aboveground allometries regarding biomass allocation (leaf mass and current-year stem mass (approximated as biomass allocated to extension growth) vs total aboveground mass) and long-term apparent growth patterns (height and aboveground mass vs age, i.e. numbers of growth rings) for nine deciduous liana species in Japan. Lianas had, on average, three- and five-fold greater leaf and current-year stem mass, respectively, than trees for a given aboveground mass, whereas the time course to reach the forest canopy was comparable and biomass accumulation during that period was only one-tenth that of co-occurring canopy trees. The balance between the lengths of yearly stem extension and existing older stems indicated that lianas lost c. 75% of stem length during growth to the canopy, which is probably a consequence of the host-dependent growth. Our observations suggest that, although lianas rely on hosts mechanically, allowing for short-term vigorous growth, this habit requires a large cost and could limit plant growth over protracted periods..
4. Ryuji Ichihashi, Hikaru Komatsu, Tomonori Kume, Yuka Onozawa, Yoshinori Shinohara, Kenji Tsuruta, Kyoichi Otsuki, Stand-scale transpiration of two moso bamboo stands with different culm densities, Ecohydrology, 10.1002/eco.1515, 8, 3, 450-459, 2015.04, The large-scale expansion of Moso bamboo forests in Japan raises concerns about how vegetation will affect the hydrological cycle and local water resources. However, information on transpiration (E) is limited to study on a single bamboo stand with low culm density (4000ha-1). The present study conducted a year-round measurement of E in a high-density (11000ha-1) stand using sap-flow measurements, and additional measurements were made during summer in the previously studied low-density stand and a neighbouring Japanese cedar stand for comparison. Annual E of the high-density stand was estimated at 455mm. Although the value was greater than those reported for neighbouring coniferous forests (250-370mm), it was lower than previous measurements made in the low-density stand (567mm). The daytime sap flux density of the high-density stand was generally less than half that in the low-density stand, resulting in similar daily maximum E values in those stands. In addition, E typically peaked before midday in the high-density stand followed by a rapid decline; the midday suppression of E led to decreased total E in the stand. Based on present and previous measurements of E, combined with the lower rainfall interception (I) reported for bamboo stands, water loss through evapotranspiration would be comparable between bamboo and coniferous forests. Present results also suggest that the E of bamboo stands does not have strong positive relationships with stand structural parameters (e.g., culm density and sapwood area) but possibly depends more on the sites' microenvironments (e.g., solar radiation)..
5. Ryuji Ichihashi, Masaki Tateno, Strategies to balance between light acquisition and the risk of falls of four temperate liana species
To overtop host canopies or not?, Journal of Ecology, 10.1111/j.1365-2745.2011.01808.x, 99, 4, 1071-1080, 2011.07, 1.Lianas face a dilemma: how can they achieve a balance between the benefits they gain from light capture in their host canopies and the risk of falls resulting from the deleterious effects they have on the growth and survival of their host trees? To address this issue, we investigated leaf distribution patterns, canopy dynamics and the impact of four liana species on the growth of their hosts. 2.In the forest canopy, the majority of the leaves of Actinidia arguta (Actinidiaceae) received >80% irradiance relative to the canopy top. The leaf mass and the length of the canopy framework of this species increased linearly with time after it had reached the forest canopy (estimated from the number of growth rings in the main liana stem at 8m height). In contrast, a much lower percentage irradiance was received by leaves of the three other species, Celastrus orbiculatus (40-80%, Celastraceae), Schisandra repanda (<40%, Schisandraceae) and Schizophragma hydrangeoides (<20%, Hydrangeaceae). In these species, canopy sizes did not change markedly with time. Species that intercepted more light acquired a larger number of host trees. 3.Growth-ring widths of the host trees of A. arguta and C. orbiculatus were smaller than those of liana-free trees; this difference was not significant in the two species that intercepted less light. The length of the basal stem between the rooting point and the point of attachment to the current host tree was greater in species that intercepted more light, suggesting the successful movement of these lianas to new hosts following the death of previous host trees. 4.Synthesis. Lianas have various ecological strategies for resolving their dilemma. They may be aggressive and rapidly spread in host canopies, intercepting much light, but reducing the risk of falls by acquiring many host trees to balance their top-heavy architecture. Alternatively, they may be commensal, whereby small liana canopies in lower positions in their host canopies acquire less light, but do not negatively affect the current hosts. Such variations reflect niche differentiation among species, and could be an important mechanism underlying the diversification and coexistence of liana species..
6. Ryuji Ichihashi, Hisae Nagashima, Masaki Tateno, Biomass allocation between extension- and leaf display-oriented shoots in relation to habitat differentiation among five deciduous liana species in a Japanese cool-temperate forest, Plant Ecology, 10.1007/s11258-010-9783-0, 211, 1, 181-190, 2010.10, Liana species have a variety of habitat preferences. Although morphological traits connected to resource acquisition may vary by habitat preference, few studies have investigated such associations in lianas. In previous work on temperate lianas, we observed (1) free standing leafy shoots and (2) climbing shoots that clung to host plants; we examined relationships between habitat preference and shoot production patterns in five liana species. Among the five species, two were more frequent at the forest edges (forest-edge species), and two were more common within the forests (forest-interior species). The proportion of climbing shoots in current-year shoot mass of young plants (3-8 m in height) was greater in the forest-edge species (45-60%) than in the forest-interior species (6-30%). In consequence, there was a greater leaf mass ratio in the total current-year shoots of forest-interior species. This, combined with a greater specific leaf area, endows forest-interior species with a leaf area per unit shoot mass double that of forest-edge species. Forest-edge species had longer individual climbing shoots whose length per unit stem mass was smaller than in forest-interior lianas. Extension efficiency, measured as the sum of the climbing stem length per unit current-year shoot mass, was thus similar between forest-edge and interior species. In conclusion, liana shoot production patterns were related to species habitat preferences. A trade-off between current potential productivity (leaves) and the ability to search for hosts and/or well-lit environments (climbing stems) may underpin these relationships..
Membership in Academic Society
  • Ecological Society of Japan