京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19221号 / 理博第4113号 / 新制||理||1592(附属図書館) / 32220 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 伊谷 原一, 教授 幸島 司郎, 教授 村山 美穂 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20048号 / 理博第4233号 / 新制||理||1609(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 中川 尚史, 教授 沼田 英治, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20962号 / 理博第4414号 / 新制||理||1634(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 湯本 貴和, 教授 古市 剛史, 教授 友永 雅己 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Planted pine (Pinus spp.) comprises nearly 10% of the total land cover in the state of Mississippi. Often, understory structure is limited in this system. Thus, managers use a variety of management practices to improve understory biomass and structure. I assessed the impacts of common forest management practices (canopy reduction, prescribed fire, and selective herbicide application) and their combined effects on aspects of community structure. More specifically, I assessed impacts of disturbance intensity on non-native plant invasions, and evaluated how microscale vegetation characteristics influenced use by white-tailed deer (Odocoileus virginianus) and wild turkey (Mealagris gallopavo). Combining canopy reductions with prescribed fire, which closely mimicked historical intermediate disturbance intensities in this vegetation type, led to the greatest invasion resistance due to high abundances of native plants. Both deer and turkey increased use in areas with high levels of understory cover. Coupling canopy reductions with prescribed fire created the most favorable conditions for both species.

Understanding the movement phenology of the four-toed salamander (Hemidactylium scutatum) is essential to guide management practices. I examined the relationship between environmental variables and the directionality, timing, and magnitude of four-toed salamander movements at two locations in eastern Massachusetts. Four-toed salamanders move from upland habitats to wetland areas in early spring and move away from wetlands in late spring. Adult movements increased with more precipitation and less moon light. Juvenile movements were similarly affected, and in addition they were more likely to move when temperatures were warm and days long. My results can be used to implement management strategies aimed at reducing human-related impacts on migrating four-toed salamanders (e.g., road closures to reduce road mortality). In addition, I developed and evaluated the accuracy of classification and regression tree (CART) models at multiple spatial scales to predict suitable habitat and potential species occurrences of the four-toed salamander (Hemidactylium scutatum) in Massachusetts. I analyzed four-toed salamander Element Occurrence (EO) observations reported during 1990-2009 in response to fifteen environmental predictor variables at six different local and landscape-scales. The landscape-scale model measured at 2000 m was most successful at predicting four-toed salamander habitat. It correctly classified 92.4% of the training data and 87.7% of the verification data. When the 2000 m model was applied statewide, 30,195 wetlands were determined to be potentially suitable habitat for the four-toed salamander. The results of this study confirm the potential and value of classification and regression tree models for identifying potential habitat for rare or cryptic species.

Oxbow lakes are highly productive waterbodies that host multiple life stages of many freshwater aquatic species. Oxbow lakes also provide habitat to Silver Carp (Hypophthalmichthys molitrix), which has enabled populations to grow and expand within the United States. Silver Carp are undesirable because they can compete for resources with native fishes. My goal was to identify patterns of distribution and dispersion of Silver Carp in Moon Lake, Mississippi, to assist and inform precise harvesting of fish. I implanted thirty-five adult Silver Carp with acoustic tags that I released into Moon Lake. I observed that Silver Carp were disproportionately found in locations where water depths ranged from 2.0-5.9 m during all seasons, despite the availability of locations with shallower and deeper water. Silver Carp did aggregate in the wintertime (December-February) in comparison to all other seasons. This information about depth distributions and seasonal aggregations can inform removal programs.

An intensive, replicated monthly sampling of snake communities inhabiting four habitat types was conducted at John F. Kennedy Space Center, Brevard County, Florida from November 2002 through October 2003. Thirteen species (580 individuals plus 74 recaptures) plus one hybrid were captured. The three most commonly captured species, Coluber constrictor, Thamnophis sirtalis, and Thamnophis sauritus, combined made up 85% of the sample. These three species were active during every month of the year, but showed modal activity patterns typical of Temperate Zone snakes. Monthly snake captures were correlated with monthly captures of potential prey species and with mean monthly temperature. Species richness in the four habitat types varied from nine to 12. Drift fences in ruderal habitats had the highest species richness, while fences in swales captured the greatest number of individuals. The most dissimilar habitat pair was scrub and swale, while the most similar pair was ruderal and hammock. Box traps proved more effective for targeting the largest snake species, while funnel and box traps were equally effective for targeting other species.

Successful recovery of the federally threatened southeastern beach mouse (Peromyscus polionotus niveiventris) depends in part on an understanding of their habitat requirements. I studied habitat use by beach mice at Cape Canaveral Air Force Station, Florida from March 2005 until March 2006. I livetrapped six grids, three on coastal dunes and three within scrub located inland from the coast. On each grid and trap station, I quantified the extent of bare ground, woody vegetation, non-woody vegetation, height of vegetation, and percentage of coarse sand in the surface soil. I assessed trap success relative to these habitat variables using linear and multiple regression, correlation, and ordination. Significantly higher numbers of mice were captured in the scrub habitat relative to the coastal habitat. Linear regression of trap success against the habitat variables did not reveal any significant relationships at the level of grids. A non-metric multidimensional scaling model was designed to capture the vegetation heterogeneity at the trapping sites and clarify the results. This methodology identified a predominantly dune and predominately scrub cluster of trap sites. A bubble plot showed higher densities of beach mice using the scrub habitat types. These results suggest beach mice are selecting for those habitat variables defined by the ordination: higher vegetation height, more woody vegetation types, less bare ground, and less heterogeneity.

Sumatran elephant (Elephas maximus sumatranus) populations continue to decline due to habitat loss, poaching and conflict with humans. In Sumatra, elephant populations are fragmented into small isolated populations and increasingly cause conflict with humans. Yet, habitat loss due to the rapid land conversion for development is continuing an alarming situation. Developing effective land conservation strategies for elephants is difficult because there is little information available on foraging ecology, habitat use, movements and home range behaviors. I conducted a study on these topics in Seblat, Bengkulu Province, Sumatra during 2007-2008. The five important families of plants in the elephant diet in Sumatra ar: Moraceae, Arecaceae, Fabaceae, Poaceae,and Euphorbiacea. Elephants in Seblat tend to browse more than graze and elephants tend to browse more during the wet season. The nutritional quality (Crude Protein, Calcium, Phosphorus and Gross Energy) of elephant diet in Seblat is suitable to support population reproduction and growth. Home range size of one telemetered 97.4 km2 for the MCP and 95.0 km2 for the 95% fixed kernel. There was no relation between average monthly elephant home range sizes and rainfall, nor any correlation between monthly elephant movement distances and rainfall. Vegetation productivity, as measured by the Enhanced Vegetation Index (EVI), was probably the factor most affecting elephant movements compared to the distances to rivers and ex-logging roads on the SECC. Resource selection analyzes indicate that elephants in Seblat seem to select medium canopy and open canopy areas more than expected. Similarly, habitat ranking using compositional analysis shows that in 2nd order and 3rd order selection, medium canopy and open canopy were the two habitat types with a greater level of used. Habitat use based on diurnal and nocturnal elephant activities indicates that elephants preferred closed canopy habitat compare to the open canopy habitat during the day. The results of this study suggest wide conservation implications for elephants on Sumatra, helping to guide effective land use conservation programs and provide scientific guideline to restore disturbed habitat and select priority areas for Sumatran elephants.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第24936号 / 情博第847号 / 新制||情||142(附属図書館) / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 大手 信人, 准教授 小山 里奈, 教授 三田村 啓理, 准教授 市川 光太郎 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM