DSpace Collection: 2014-08
http://hdl.handle.net/2115/56852
2014-082024-03-19T02:33:10ZDifferences in Pollen Resource Usage and Foraging Periods between the Exotic Bumblebee Bombus terrestris and the Native B. pseudobaicalensis and B. hypocrita sapporoensis in Hokkaido, Japan
http://hdl.handle.net/2115/56855
Title: Differences in Pollen Resource Usage and Foraging Periods between the Exotic Bumblebee Bombus terrestris and the Native B. pseudobaicalensis and B. hypocrita sapporoensis in Hokkaido, Japan
Authors: Nakamura, Yasuhide
Abstract: Bombus terrestris Linnaeus is an exotic bumblebee species that has recently been naturalized in Hokkaido, Japan. Some studies have suggested that the naturalization of this species has caused a decline in the native bumblebee populations. The present study focuses on differences in plant resource usage between coexisting exotic (B. terrestris) and native (B. pseudobaicalensis and B. hypocrita subsp. sapporoensis) bumblebee species in the Ishikari lowland region of Hokkaido. We observed the workers of the three species that came to forage in the investigation area during an approximately five-month period. In addition, we captured some of the bees carrying pollen to analyze the pollen grains attached to their body surfaces. The pollen grains were identified at the genus or species level. Compared with the two native species, B. terrestris workers were relatively abundant during the investigation period. This species also exhibited a relatively long duration of foraging activity and a larger foraging range than the other two native species. The patterns of pollen resource usage were generally different among the three species, suggesting that these species have different flower preferences. Cluster analysis based on use of pollen species by each worker revealed that the cluster compositions overlapped among the three species in July, but this overlap disappeared in August. The usage in pollen species tended to differ through the season.2013-12-31T15:00:00ZNakamura, YasuhideBombus terrestris Linnaeus is an exotic bumblebee species that has recently been naturalized in Hokkaido, Japan. Some studies have suggested that the naturalization of this species has caused a decline in the native bumblebee populations. The present study focuses on differences in plant resource usage between coexisting exotic (B. terrestris) and native (B. pseudobaicalensis and B. hypocrita subsp. sapporoensis) bumblebee species in the Ishikari lowland region of Hokkaido. We observed the workers of the three species that came to forage in the investigation area during an approximately five-month period. In addition, we captured some of the bees carrying pollen to analyze the pollen grains attached to their body surfaces. The pollen grains were identified at the genus or species level. Compared with the two native species, B. terrestris workers were relatively abundant during the investigation period. This species also exhibited a relatively long duration of foraging activity and a larger foraging range than the other two native species. The patterns of pollen resource usage were generally different among the three species, suggesting that these species have different flower preferences. Cluster analysis based on use of pollen species by each worker revealed that the cluster compositions overlapped among the three species in July, but this overlap disappeared in August. The usage in pollen species tended to differ through the season.Tree Shape and Resistance to Uprooting : A Simple Model Analysis
http://hdl.handle.net/2115/56854
Title: Tree Shape and Resistance to Uprooting : A Simple Model Analysis
Authors: Shibuya, Masato; Koizumi, Akio; Torita, Hiroyuki
Abstract: We examined tree resistance to uprooting in relation to tree shape using a simple, qualitative model for the ratio of the resistive moment to the overturning moment. For this analysis, we used model trees and varied the crown size for a fixed stem size for a ratio of crown mass to stem mass that varied from 0.1 to 1. The results predicted the phase transition in the resistance trend in relation to the crown mass/stem mass ratio. Resistance increased on both sides of the crown mass/stem mass ratio, and was minimized at intermediate ratios. This indicates that crown expansion contributes to resistance to the right side of minimum, and vice versa. The same trend was recognized for actual Sitka spruce tree data. These results were consistent with previous observations of tree resistance to uprooting: trees with a small slenderness ratio (ratio of height to diameter at breast height) are resistant to uprooting, and trees/stands are vulnerable to uprooting after thinning, especially after belated thinning. We recommend sparse tree densities in plantations to manage the risk of physical tree damage such as overturning and stem failure. However, quantitative analyses of wind damage to trees and stands are necessary to improve risk management of plantations. The results of this study can be incorporated into such quantitative analyses.2013-12-31T15:00:00ZShibuya, MasatoKoizumi, AkioTorita, HiroyukiWe examined tree resistance to uprooting in relation to tree shape using a simple, qualitative model for the ratio of the resistive moment to the overturning moment. For this analysis, we used model trees and varied the crown size for a fixed stem size for a ratio of crown mass to stem mass that varied from 0.1 to 1. The results predicted the phase transition in the resistance trend in relation to the crown mass/stem mass ratio. Resistance increased on both sides of the crown mass/stem mass ratio, and was minimized at intermediate ratios. This indicates that crown expansion contributes to resistance to the right side of minimum, and vice versa. The same trend was recognized for actual Sitka spruce tree data. These results were consistent with previous observations of tree resistance to uprooting: trees with a small slenderness ratio (ratio of height to diameter at breast height) are resistant to uprooting, and trees/stands are vulnerable to uprooting after thinning, especially after belated thinning. We recommend sparse tree densities in plantations to manage the risk of physical tree damage such as overturning and stem failure. However, quantitative analyses of wind damage to trees and stands are necessary to improve risk management of plantations. The results of this study can be incorporated into such quantitative analyses.Variation on Genotypes and Flowering Characters Affecting Pollination Mechanisms of Sandalwood (Santalum album Linn., Santalaceae) Planted on ex-situ gene Conservation in Yogyakarta, Indonesia
http://hdl.handle.net/2115/56853
Title: Variation on Genotypes and Flowering Characters Affecting Pollination Mechanisms of Sandalwood (Santalum album Linn., Santalaceae) Planted on ex-situ gene Conservation in Yogyakarta, Indonesia
Authors: Yeni, W. N. Ratnaningrum; Sapto, Indrioko
Abstract: This research is a part of the long term research on sandalwood improvement strategy based on gene conservation approaches, focused on gene diversity and flowering characteristics of seven sandalwood provenances planted on ex-situ gene conservation in Wanagama Forest Research Station, Yogyakarta Province, Indonesia, and its effect on pollination mechanisms. Juvenile leaves sampled from any individual of each provenance where isozyme analyses then conducted with vertical polyacrilamide gel electrophoresis procedures based on David-Ornstein method with 3 enzyme systems: SHD, EST and DIA. Standard genetic distance measured following Nei and dendrogram then made following cluster analyses based on UPGMA. Parameters of flowering measured daily on each of 10 selected individual based on Ghazoul and Owens methods. Pollination mechanisms investigated by observing the attractant availability provided by 10 marked individual of each provenance. Observation was then made on plant pollinator interactions: stigmatic contact, pollen load, interplant movement, feeding behavior and visitation rate; that were measured daily based on Ghazoul and Jones and Little methods. Provenances originated from same site performed similar genotypes as well as flowering characters. All of provenances were both protandry dichogamy and heterostyly. Variation on size and color of perigonium were found among provenances between times. Generally, provenances originated from Eastern parts of Indonesia flowered earlier compared to those of central parts of Java, with shorter period as well; while those of Bromo was the latest to flower with the longest period. There were 6 types of 3 orders of insect found to visit flowers: moths, butterflies (Lepidoptera), flies (Diptera), ants, bees and wasps (Hymenoptera). Type of insect and visitation rate depended on flowering phases in term of primary (pollen and nectar) and secondary (color of perigonium and mature anthers) attractants availability. Meanwhile, preference of visitors to visit certain provenances was affected more by secondary attractant.2013-12-31T15:00:00ZYeni, W. N. RatnaningrumSapto, IndriokoThis research is a part of the long term research on sandalwood improvement strategy based on gene conservation approaches, focused on gene diversity and flowering characteristics of seven sandalwood provenances planted on ex-situ gene conservation in Wanagama Forest Research Station, Yogyakarta Province, Indonesia, and its effect on pollination mechanisms. Juvenile leaves sampled from any individual of each provenance where isozyme analyses then conducted with vertical polyacrilamide gel electrophoresis procedures based on David-Ornstein method with 3 enzyme systems: SHD, EST and DIA. Standard genetic distance measured following Nei and dendrogram then made following cluster analyses based on UPGMA. Parameters of flowering measured daily on each of 10 selected individual based on Ghazoul and Owens methods. Pollination mechanisms investigated by observing the attractant availability provided by 10 marked individual of each provenance. Observation was then made on plant pollinator interactions: stigmatic contact, pollen load, interplant movement, feeding behavior and visitation rate; that were measured daily based on Ghazoul and Jones and Little methods. Provenances originated from same site performed similar genotypes as well as flowering characters. All of provenances were both protandry dichogamy and heterostyly. Variation on size and color of perigonium were found among provenances between times. Generally, provenances originated from Eastern parts of Indonesia flowered earlier compared to those of central parts of Java, with shorter period as well; while those of Bromo was the latest to flower with the longest period. There were 6 types of 3 orders of insect found to visit flowers: moths, butterflies (Lepidoptera), flies (Diptera), ants, bees and wasps (Hymenoptera). Type of insect and visitation rate depended on flowering phases in term of primary (pollen and nectar) and secondary (color of perigonium and mature anthers) attractants availability. Meanwhile, preference of visitors to visit certain provenances was affected more by secondary attractant.