Ph.D. - Botanical Sciences (Botany - Ecology, Evolution and Conservation Biology)

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    In the wake of ruling chiefs: Forest use on the island of Hawai'i during the time of Kamehameha I
    (University of Hawaii at Manoa, 2003-12) Pang, Benton K. ; Abbott, Isabella A ; Botanical Sciences (Botany)
    This research examines the lowland lama (Diospyros)/kauila ( Colubrina ) dry forest community subtype that exists from Ka'upulehu to Pu'uwa'awa'a. Known threats to this forest community include ranching, invasive grasses, and fire. However, impacts from Hawaiians living in the area from 1600-1800 have never been identified. This research also attempts to quantify the importance of the trees and shrubs of this dry forest ecosystem to Hawaiian cultural traditions, and to add a new description of Hawaiian ethnobotany. Trees used in the construction of houses and double hull canoes were compared to observations of houses and double hull canoes during the time of Kamehameha I from 1775-1796. The number of trees used during this period may indicate large-scale habitat modifications and extraction by Hawaiians in the North Kona region of Hawai`i Island. This region of North Kona was important to events that took place during the time of King Kamehameha (Pai`ea) from 1775-1796. The area was a location for coastal fishing, and farming of sweet potatoes. An ethnobotanical survey was conducted of the types of woods needed to construct chiefly kauhale (housing compounds) and double hull canoes that were integral to the success of Kamehameha's reign. The species and the sizes of branches and trunks were estimated to determine the amount of native hardwoods necessary to complete the known number of kauhale and war canoes that Kamehameha possessed. The population structure of the lama/kauila lowland dry forest was estimated from a fenced exclosure at Ka'upulehu that has been ungulate free for the past 39 years. The species in this exclosure were compared with botanical inventories of Pu'uwa'awa'a to the north and at the same elevational gradient. The extent of the Lowland Dry Forest in North Kona was estimated through this comparison with particular emphasis to the Lama (Diospyros )/Kauila (Colubrina) Dry Forest type.
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    Changes in growth and survival by three co-occurring grass species in response to mycorrhizae, fire, and drought
    (University of Hawaii at Manoa, 2003-05) Wilkinson, Melinda M. ; Daehler, Curtis C ; Botanical Sciences (Botany - Ecology, Evolution, & Conservation Biology)
    The goal of this study was to evaluate the effect of controlled burns, drought and the presence of arbuscular mycorrhizal fungi (AMF) on a dry coastal grassland in Hawai'i Volcanoes National Park. Two introduced African grasses, Hyparrhenia rufa thatching grass, and Melinis repens - Natal redtop, along with one indigenous grass Heteropogon contortus - pili grass composed most of the cover at the study sites. The response of the grasses to fire, AMF infection potential of the soil, and in situ seedling AMF infection were monitored in the field for three years from 1997 to 2000 at Keauhou, Ka'aha, and Kealakomo in Hawai'i Volcanoes National Park. A greenhouse experiment compared the competitive ability of the three grasses with or without AMP inoculation or water stress. The population dynamics of the three grasses were modeled based on their responses to fire, AMF infection, competition and water. At low fire intensities Heteropogon and Hyparrhenia had similar high survival rates while Melinis had a low survival rate. At higher fire intensities all species had low survival rates. The fire decreased the AMF infection potential of the soil at Kaaha, but in situ seedlings AMF infection levels remained high and not statically between the burned and unburned Kaaha sites. In the greenhouse portion of this study Heteropogon biomass increased in response to AMF infection while the other two species did not respond positively to infection. These results suggest that AM fungi increase the growth of the native species, thereby decreasing the impact of competition from two co-occurring alien grasses. When population dynamics were modeled to include the effects of fire, drought and AMF, Melinis and Hyparrhenia produced more biomass in the simulations than the native grass Heteropogon. Drought and AMF decreased the difference in biomass production between the species but did not reverse the competitive ranking of the species.
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    Ecology and biology of the rough-toothed dolphin (Steno bredanensis)
    (University of Hawaii at Manoa, 2002-12) West, Kristi Lee ; Whittow, G Cansey ; Biomedical Sciences (Physiology)
    Greater knowledge of the rough-toothed dolphin, Steno bredanensis, is needed to effectively contribute to conservation and management efforts for this species. The primary purpose of this research was to describe ecological and biological parameters for S. bredanensis that will be useful in future assessments of population stress. Several approaches were used to study S. bredanensis, including investigations of free-ranging populations, dead specimens, and captive individuals. Free-ranging rough-toothed dolphins distributed near small oceanic island environments were found to be more commonly sighted in-shore than off-shore. In the Windward islands of French Polynesia, this species preferred water depths of 1000 to 2000m and a distance of 1.8 to 5.5 km from the barrier reef. Group sizes ofrough-toothed dolphins sighted in French Polynesia range between 1 and 35 individuals with a mean size of 12.1. Endocrinology data for S. bredanensis was established in captive healthy and stranded individuals. Ranges and means were provided for progesterone, testosterone, cortisol and thyroid hormones. Changes in thyroid hormone concentrations were reflective of health status and testosterone appeared to be suppressed in ill individuals. Reproduction in S. bredanensis was investigated by determining the size and age range that this species attains sexual and physical maturity. Female rough-toothed dolphins attain sexual maturity by 9 to 10 years of age and males between 5 and 10 years at a similar length of approximately 216 cm. Physical maturity is generally reached at an older age and larger size for both males and females. Ecologically healthy and unheahhy populations of S. bredanensis were described in this investigation and these fmding will be useful in assessing future threats to this species.