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Papers by Tatsuhiro Ohkubo

Ecology Letters, 2006

Tropical forests vary substantially in the densities of trees of different sizes and thus in abov... more Tropical forests vary substantially in the densities of trees of different sizes and thus in above-ground biomass and carbon stores. However, these tree size distributions show fundamental similarities suggestive of underlying general principles. The theory of metabolic ecology predicts that tree abundances will scale as the)2 power of diameter. Demographic equilibrium theory explains tree abundances in terms of the scaling of growth and mortality. We use demographic equilibrium theory to derive analytic predictions for tree size distributions corresponding to different growth and mortality functions. We test both sets of predictions using data from 14 large-scale tropical forest plots encompassing censuses of 473 ha and > 2 million trees. The data are uniformly inconsistent with the predictions of metabolic ecology. In most forests, size distributions are much closer to the predictions of demographic equilibrium, and thus, intersite variation in size distributions is explained partly by intersite variation in growth and mortality.

Journal of Tropical Ecology, 2000

Biotropica, 2014

ABSTRACT Continually flowering plants bloom continuously throughout the year, as often seen in pl... more ABSTRACT Continually flowering plants bloom continuously throughout the year, as often seen in plants distributed along the roadsides or in the understory layers in Southeast Asia's tropical rain forests. Dillenia suffruticosa (Griff. ex Hook. f. & Thomson) Martelli (Dilleniaceae) is one such continually flowering shrub that flowers during periods of community-wide mass flowering, general flowering (GF), and non-GF. During irregularly occurring GF periods, when species of all forest layers flower synchronously for several months, some pollinators migrate to the canopy layer, where GF promotes the pollination success of participating plants. Continually flowering plants share the available pollinator community with GF plants, and the reproductive success of continually flowering plants may be affected during the GF period. To assess the effects of GF on the reproductive success of a diverse range of continually flowering plants, we examined the differences in pollinator density and reproductive success between GF and non-GF periods in D. suffruticosa at four different research sites. Although the seed set differed among the four research sites, pollinator density and fruit set did not differ between GF and non-GF periods or research sites. Our results suggest that the reproductive success of D. suffruticosa was maintained at an approximately constant level, regardless of the flowering phenology of the canopy layer or other vegetation components.

Neuroradiology, Nov 1, 1996

ABSTRACT

Journal of Sustainable Forestry, Oct 12, 2008

Abstract In order to clarify mechanisms of canopy recruitment of Fagus japonica stems of sprout o... more Abstract In order to clarify mechanisms of canopy recruitment of Fagus japonica stems of sprout origin, age structure and growth dynamics were studied for stems within beech stools in two stands of old growth forests on the Pacific side of central Japan. The DBH vs. height ...

Biotropica

Continually flowering plants bloom continuously throughout the year, as often seen in plants dist... more Continually flowering plants bloom continuously throughout the year, as often seen in plants distributed along the roadsides or in the understory layers in Southeast Asia's tropical rain forests. Dillenia suffruticosa (Griff. ex Hook. f. & Thomson) Martelli (Dilleniaceae) is one such continually flowering shrub that flowers during periods of community-wide mass flowering, general flowering (GF), and non-GF. During irregularly occurring GF periods, when species of all forest layers flower synchronously for several months, some pollinators migrate to the canopy layer, where GF promotes the pollination success of participating plants. Continually flowering plants share the available pollinator community with GF plants, and the reproductive success of continually flowering plants may be affected during the GF period. To assess the effects of GF on the reproductive success of a diverse range of continually flowering plants, we examined the differences in pollinator density and reprod...

Shokubutsu Kojo Gakkaishi, 2004

122 ffifäXigif kIÈ(Journal of Society of High Technology in Agriculture) 16 (3) : 122 -130. 2004.... more 122 ffifäXigif kIÈ(Journal of Society of High Technology in Agriculture) 16 (3) : 122 -130. 2004. Micropropagation of Plantlets through Callus in Kihada (Phellodendron amurense Rupr.) Mustafa Abul Kalam AZAD1'2, Shinso Yokota2, Tatsuhiro OHKUBO2, Yasuhiro ...

Journal of Weed Science and Technology, 2005

British journal of cancer, Jan 15, 2003

A phase II study of cisplatin, ifosfamide, and irinotecan with recombinant human granulocyte colo... more A phase II study of cisplatin, ifosfamide, and irinotecan with recombinant human granulocyte colony stimulating factor (rhG-CSF) support was conducted in previously untreated patients with stage IIIB or IV non-small-cell lung cancer (NSCLC). Between June 1998 and August 2001, 50 patients were registered in this phase II study. Cisplatin (20 mg m(-2)) and ifosfamide (1.5 g m(-2)) were administered on days 1-4 and irinotecan (60 mg m(-2)) was given on days 1, 8, and 15, respectively. This regimen was repeated every 4 weeks. rhG-CSF was administered subcutaneously at a dose of 50 microg m(-2) on days 5-18 except on the days of irinotecan treatment. In total, 49 patients were assessable for toxicity and response and 50 for survival. In all, 33, patients (67.3%; 95% confidence interval 57.4-77.2%) achieved an objective response. The median response duration was 192 days and the median time to progression for 49 patients was 170 days. The median survival time was 540 days with 1- and 2-ye...

Vegetatio, 1996

The response of Japanese beech (Fagusjaponica Maxim.) sprouts to canopy gaps in natural beech for... more The response of Japanese beech (Fagusjaponica Maxim.) sprouts to canopy gaps in natural beech forest in central Japan was studied using two contrasted gaps in which tree-ring chronologies of regenerating stems were analyzed. The gaps were created by uprooting of a single Quercus mongolica var. grosseserrata stem (diameter: 50 cm; gap size: 40 m2; 23 years old) and by concurrent uprootings of four E japonica stools (gap size: 180 m2; 30 years old).

Plant Biotechnology, 2007

When plantlets are transplanted from an in vitro culture to greenhouse conditions, they often des... more When plantlets are transplanted from an in vitro culture to greenhouse conditions, they often desiccate or wilt rapidly and finally die due to their undeveloped histological structures. Consequently, substantial precautions must be taken after transfer to open air and soil so ...

Journal of Weed Science and Technology, 2006

Stroke, 2008

Background and Purpose-Smoking and increased levels of blood pressure (BP) substantially increase... more Background and Purpose-Smoking and increased levels of blood pressure (BP) substantially increase the risk of cardiovascular diseases (CVD). If these 2 risk factors have a synergistic impact on cardiovascular events, lowering BP and quitting smoking will contribute more to reducing CVD than would be expected from ignoring their interaction. Methods-Individual participant data were combined from 41 cohorts, involving 563 144 participants (82% Asian). During a median of 6.8 years follow-up, 4344 coronary heart disease (CHD) and 5906 stroke events were recorded. Repeat measures of systolic blood pressure (SBP) were used to adjust for regression dilution bias. Hazard ratios (HRs) and 95% confidence intervals (CIs) for SBP by cigarette smoking status were estimated from Cox proportional hazard models adjusted for age and stratified by study and sex.