Climate and vegetation history of the midcontinent from 75 to 25 ka: A speleothem record from crevice cave, missouri, USA

Four Missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago (ka). The thorium-230-dated records reveal that between 75 and 55 ka, the midcontinental climate oscillated on millennial time scales between cold and warm, and vegetation alternated among forest, savanna, and prairie. Temperatures were highest and prairie vegetation peaked between 59 and 55 ka. Climate cooled and forest replaced grassland at 55 ka, when global ice sheets began to build during the early part of Marine Oxygen Isotope Stage 3.     

Comparisons of hyphal growth of Raffaelea quercivora among four Japanese Fagaceae species

Japanese oak wilt causes widespread oak mortality in Japan. Possible differences in susceptibility to the causal fungus, Raffaelea quercivora, may be due to vessel arrangements in host trees. To clarify whether constitutive defence mechanisms including vessel arrangements or induced defence mechanisms are the main determinants of host susceptibility, we inoculated the fungus into living seedlings or sterilized stem segments of four Japanese fagaceous species. In seedlings, water conductance was assessed with dye. In both seedlings and stem segments, hyphal growth was examined by fluorescence microscopy. In seedlings, the area of non‐conductive sapwood in stem cross sections and hyphal growth differed significantly among species. In the susceptible species Quercus crispula and Quercus serrata, hyphal growth was significantly and positively correlated with the proportion of non‐conductive sapwood. In stem segments, hyphal growth was not significantly different among species or between vessel arrangements and was similar to or greater than that in seedlings. These results suggest that the extent of sapwood colonization by R. quercivora could be used as a marker for susceptibility and that susceptibility is determined mainly by induced defence responses.     

Heat budget and statistical analysis of the relationship between stream temperature and riparian forest in the Toikanbetsu River basin, northern Japan

Riparian forests greatly influence aquatic ecosystems by providing shade cover, which controls water temperature and limits primary production. We examined the relationship between forest cover and summer stream temperature in northernmost Japan. Heat budget and statistical analyses were employed and the results were compared. Heat budget analysis revealed that the water temperature would decrease almost linearly from 29°C to 25°C with an increase in forested reaches along a 3.2 km stretch of the river. Multiple regression analysis by the stepwise method chose only open channel length as a variable to explain the variation in maximum stream temperature. A sharp increase in stream temperature was noted when riparian forest cover was removed in short lengths, of up to 1.0km; this increasing trend gradually flattened as the length of open stretch increased. Thus, even small openings in the riparian canopy resulted in drastic rises in summer stream temperature. The maximum summer temperatures estimated by the two methods were coincided, and can therefore be accurately estimated by regression analysis. Retrospective analysis based on the regression equation showed that the maximum summer temperature in 1947 was 6°C lower than at present, and that a sharp increase occurred from 1947 to 1960, a period of rapid expansion of agricultural land development in the watershed.     

Investigation of relationships between cell and pulp properties in Eucalyptus by examination of within-tree property variations

 Relationships between cell and pulp properties were investigated by examining the within-tree property variations in Eucalyptus camaldulensis and Eucalyptus globulus. Properties investigated included proportions of ray and axial parenchyma, thickness of cell walls and cell wall percentages. The characteristics of the ray and axial parenchyma (their proportions and wall thickness) were found to have a significant influence on all measured pulp properties, including paper strength properties. Multiple regression of pulp properties in relation to cell properties revealed that nearly all measured pulp properties were explained by cell properties at the 1% significance level. It was concluded, therefore, that all cell types are important for predicting pulp properties, and it is strongly recommended that tree breeding programs for Eucalyptus include the measurement of all cell types. Received 6 July 1999     

Effect of shoot size and phenological variation of host plants on the spatial patterns of cynipid galls

The effects of shoot size and differences in budburst phenology ofQuercus serrata trees on the spatial patterns of galls were investigated for two cynipid species: the sexual generation ofAndricus moriokae and the agamic generation ofAphelonyx glanduliferae. There were marked differences in budburst phenology, but these did not affect the gall density on the tree. The galls of both cynipids showed a contagious distribution in their respective trees, but different abundance patterns under high gall density. The mean number of galls ofA. glanduliferae over a shoot size range was positively correlated with shoot size. More galls ofA. moriokae appeared on larger shoots on trees on which many buds had started growing before oviposition by the agamic adults. In the case of a tree on which a few buds had burst by the time of oviposition, the mean numbers ofA. moriokae galls on shoots of particular size ranges depended on the frequency of shoots in the size class. These results suggest that, although these cynipids prefer to attack larger shoots within a host tree, they may exhibit plasticity in their preference in response to changes in budburst phenology of the host plant relative to the time of oviposition.     

Stocking effectiveness of hatchery-released kuruma prawns estimated by two-stage sampling of commercial catch in Ariake Sound, Japan

ABSTRACT:    To evaluate the stocking effectiveness of the kuruma prawn Penaeus japonicus , a two-stage sampling survey of Gensiki bottom-drift-netters was carried out in Ariake Sound, Saga Prefecture, Japan. A total of 471 000 hatchery-produced juveniles, marked by cutting off the right uropods, was released. Thirty-three fishing days were randomly drawn from four boats, which were selected from the 80 boats operating in the fishery. All prawns caught on the selected days were examined, and the hatchery-produced individuals were identified by their regenerated uropods. A telephone survey of all boats was also conducted, to determine the number of fishing days. A total of 286 marked prawns were caught on the survey days for the Saga area in Ariake Sound, from the last half of July to the first half of September 2002. The recapture rate and standard error were estimated at 0.76 ± 0.52%. Economic efficiency was estimated at 0.28 ± 0.02. Strategies for sampling schemes and stock recovery are also discussed.     

Relationship of climatic conditions to fecal corticosterone levels of captive cheetahs reared in Japan

To assess the stress level of cheetahs reared in Japan and to identify the prime components of the climatic conditions that affect their thermal stress, fecal corticosterone was monitored for 8 months from May to the following January. A total of 203 fecal samples were gathered in the morning from seven adult cheetahs that were kept at a zoological garden in Wakayama, Japan. Cheetahs were on exhibit singly or together with a harmonious conspecific during the day, but housed singly at night. Although the monthly fluctuation in corticosterone concentrations was not significant, the concentrations were relatively low during the summer season. Individual differences among cheetahs and the interaction effect between individual and month on the corticosterone concentrations were significant. Whereas the corticosterone concentrations negatively correlated with air temperature, they were positively correlated with the amount of rainfall. The highest air temperature and the amount of rainfall were extracted as the prime factors affecting corticosterone concentrations. These results suggest that cheetahs reared in Japan are somewhat subjected to thermal stress, particularly on cooler and/or rainy days.