環境科学院 植物生態学セミナー   2013-01-15 (Tue) 10:30
(Room: A809 )

A comparative study of aboveground allometries and biomass allocations between bamboos and trees in a Southeast Asian tropical rainforest.

Juni Fujinuma

n the lowlight understory of tropical rainforests plant architecture reflects the light capture strategy of plants. Previous studies of plant architecture have focused mostly on dicot trees that exhibit secondary growth making findings from these studies difficult to generalize to plants that lack secondary growth. This study compared the allometries and the biomass allocations between trees and bamboos in a Peninsular Malaysia tropical forest to elucidate strategic differences between plants with and without secondary growth. Two architecturally contrasting bamboo species, Gigantochloa ligulata and Schizostachyum grande, were studied and their architectural traits: height, crown area and ramet size distribution quantified. For each observed bamboo, one representative ramet was also harvested in order to measure and estimate biomass allocations between leaves, branches and culm. We compared observations with data from coexisting trees and data from Yamakura et al. 1986, applying standardized major axis regression model. We found that bamboos showed more allocation of biomass to branches than trees, and in large ramets more leaf and height were supported by relatively smaller amount of supporting organs than trees. At a genet scale, bamboos exhibited wider crown area than trees of the same biomass and the leaf area index of the bamboos were not different from trees. Overall the bamboos tended to show mechanically branch and leaf weighted architecture which potentially has higher risk of culm buckling. We hypothesize that this risky investment on productive organ is feasible by the specific life form of bamboos where a death of short-lived ramet is not critical to genet and the architecture of each ramet can ignore the consequence of the secondary growth which is absent in bamboos. These contrasting characteristics between bamboos and trees indicate the differences in strategies of how to deal with disturbance event and to capture light resource.


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