Thesis (M.Soc.Sc.)--University of Hong Kong, 1991. / Also available in print.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006. / "Title from dissertation home page (viewed July 10, 2007)." Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4209. Adviser: Edmund D. Brodie, III.

Thesis (M.A.B.S.)--Multnomah School of the Bible, 1986. / Includes bibliographical references (leaves 50-54).

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006. / "Title from dissertation home page (viewed June 27, 2007)." Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 2934. Adviser: Craig Nelson.

Anthropogenic climate change is altering phenology—the timing of biological events, including leafing and flowering—with repercussions for trophic interactions, competition, and species’ persistence. My dissertation aims to uncover, compile, and analyze resources documenting changes in species abundance and phenology in an iconic location (Acadia National Park and surrounding areas) in an understudied region of northern New England. I used the journal of a hunting guide living in Oxbow, Maine in the mid-20th century to document the climate sensitivity of leafing, flowering, and migratory bird arrivals. In Acadia National Park, Maine, I examined changes in the abundance of species by analyzing data from past and contemporary published floras for the park, and published analyses of floristic change from elsewhere in the northeastern United States. I used reciprocal transplants in common gardens and trail-side monitoring across elevation gradients in Acadia to examine inter- and intraspecific variation in plant phenology. Results showed that many native species declined in abundance or disappeared from the flora of Acadia over the past 120 years, similar to changes in floras elsewhere in New England. However, changes in the abundance of particular species in southern New England are not predictive of how they changed in Acadia. Some plant families (e.g. Orchidaceae and Liliaceae) declined disproportionately, but plant vulnerability was not related to habitat preference or range. The phenology of leaf out, flowering and migratory bird arrivals in and around Acadia demonstrate advances in response to warmer temperatures, albeit more slowly than plants in southern New England. Within Acadia, the temperature of local microclimates is a better predictor of plant phenology than elevation or aspect. Local adaption in leaf-out phenology sensitivity was not significant as populations from across a range of elevations responded similarly to different local microclimates in common gardens. This pattern contrasts with other montane systems where high elevation populations displayed reduced phenological sensitivity compared to low elevation populations. The results of this dissertation research underscore the importance of local data and of combining data from multiple sources (historical records, new field observations, and experiments) to describe changes in plant abundance and phenology, to assess species vulnerability, and to support decisions regarding future management and monitoring.

abstract: A global warming of two degrees Celsius is predicted to drive almost half the world's lizard populations to extinction. Currently, the Phoenix metropolitan region in Arizona, USA, is an average of 3 oC warmer than the surrounding desert. Using a bare lot as a control, I placed copper lizard models with data loggers in several vegetation and irrigation treatments that represent the dominant backyard landscaping styles in Phoenix (grassy mesic with mist irrigation, drip irrigated xeric, unirrigated native, and a hybrid style known as oasis). Lizard activity time in summer is currently restricted to a few hours in un-irrigated native desert landscaping, while heavily irrigated grass and shade trees allow for continual activity during even the hottest days. Maintaining the existing diversity of landscaping styles (as part of an ongoing mitigation strategy targeted at humans) will be beneficial for lizards. Fourteen native lizard species inhabit the desert surrounding Phoenix, AZ, USA, but only two species persist within heavily developed areas. This pattern is best explained by a combination of socioeconomic status, land cover, and location. Lizard diversity is highest in affluent areas and lizard abundance is greatest near large patches of open desert. The percentage of building cover has a strong negative impact on both diversity and abundance. Despite Phoenix's intense urban heat island effect, which strongly constrains the potential activity and microhabitat use of lizards in summer, thermal patterns have not yet impacted their distribution and relative abundance at larger scales. / Dissertation/Thesis / Doctoral Dissertation Biology 2015

<p> The spatial grain¹ at which ecological patterns are observed profoundly influences the inferences made about the underlying processes. In the case of species responses to environmental variation, only a limited number of grains &ndash; which I term "response grains" &ndash; are biologically meaningful to a particular species. In section I of this thesis, I summarize the development of this concept in ecology, describe its significance for ecological inference and information intended to support conservation planning, and introduce several potential approaches to measure &ndash; both directly and indirectly &ndash; a species' response grain(s).</p><p> While multi-grain studies of species-environment relationships are now relatively common, such studies typically consider a limited number of grains, based on either the spatial resolution of available environmental data, or the dimensions of landscape features predicted to be important for the species of interest (e.g. a reproductive site or an important food resource). The potentially confounding influences of environment spatial structure, and the spatial grain at which the analysis itself is performed ("analysis grain"), are often not considered. In section II of this thesis, I describe these important aspects of scale, and use a virtual species analysis to investigate their individual and joint impacts 'I use the terms "grain" and "extent" as commonly applied in geography and ecology. Spatial "grain" refers to the minimum mapping unit, analogous to a pixel or grid cell, and is most similar to the term "resolution." Spatial "extent" refers to the total area under consideration, and is equivalent to the concept of "study area." on the ability of standard analysis methods to detect and measure species-environment relationships. I show that the explanatory power of simple species distribution models generally declines with analysis grain. Moreover, a coarser response grain by the virtual species only marginally mitigates this trend, indicating that measurements of species-environment relationships at coarse analysis grains may not be wholly reliable.</p><p> In section III of this thesis, I synthesize ecological theory to describe two likely response grains for mobile vertebrate species: one equivalent to the (relatively fine) grain at which individuals identify profitable areas and use environmental resources, and a second equivalent to the (relatively coarse) grain equivalent to a species' typical home range. Based on the hierarchical structure of species-environment associations expected from well-established ecological theory, I extend occupancy modeling methods to develop a multi-grain, multi-level occupancy model. Through scale optimization within one model level, I measure the finest response grain for <i>Tockus deckeni</i> &ndash; a medium-sized, omnivorous hornbill native to East African savannas. By disentangling this species' niche relationships at multiple grains, we reveal that fine sites suitable for <i>T. deckeni</i> use are much more abundant than coarse sites suitable for its occupancy.</p><p> While ecological theory suggests that several species traits or attributes &ndash; primarily body size, home range size, trophic level, and degree of environmental or dietary specialization &ndash; determine the size of a species' response grain, very few studies have tested these expectations. In section IV of this thesis, I apply two approaches from the field of movement ecology to a large set of GPS telemetry data from four East African birds of varying body sizes Animal movement trajectories record the responses of individuals to the environmental conditions they encounter; thus, movement data should be particularly well suited to provide information about response grain. We find that, in general, response grain increases with both trophic position and home range size. Some study species exhibited a much smaller response grain than expected (under the most well-established theoretical expectation, based on body size), likely due to its low trophic position, narrow diet, and geometric constraints imposed by a small home range.</p><p> In section V of this thesis, I discuss how the information gained about species response grains in sections I &ndash; IV should be interpreted and applied in the contemporary context of modeling species distributions under expected changes to climate and land use. Analysts often select a "fine, local" or "coarse, range-wide" modeling approach based on the available data on environmental conditions and occurrences of the species of interest. However, in identifying multiple response grains and sets of species-environment relationships, we have shown that these two approaches capture different (though not strictly independent) ecological processes. Given these findings, as well as recent rapid expansions in sources of occurrence and environmental data, I provide practical advice for analysts Finally, I express several concluding thoughts about the overall work presented here.</p><p> ¹I use the terms "grain" and "extent" as commonly applied in geography and ecology. Spatial "grain" refers to the minimum mapping unit, analogous to a pixel or grid cell, and is most similar to the term "resolution." Spatial "extent" refers to the total area under consideration, and is equivalent to the concept of "study area."</p><p>

<p> Many important wetland functions are tied to sediment dynamics, which are largely governed by infaunal invertebrate communities. These communities are sensitive to changes in sediment structure and to colonization by non-native species. In a southern California salt marsh, the non-native Australian isopod <i> Sphaeroma quoianum</i> has created dense networks of burrows within the marsh banks. Since this isopod increases erosion in other areas and changes local communities, its possible contribution to habitat loss in this already-scarce southern California ecosystem is an important question. This study investigated invertebrate community composition, sediment respiration, and sediment characteristics, and connected <i>S. quoianum</i> burrows to increased proportions of crustaceans, decreased carbon content, and steep marsh bluffs and highlights the potential susceptibility of early successional salt marsh habitat to invasion by non-native species and subsequent changes in ecosystem function. These results suggest that <i>S. quoianum</i> invasion of salt marsh habitats can alter native communities and ecosystem functions. </p><p>

<p> Eurasian frogs-bit, <i>Hydrocharis morsus-ranae</i> L. is a nonnative, invasive, free-floating freshwater macrophyte first deliberately introduced into Ottawa, Canada in 1932. Although the introduction, escape, and subsequent spread in North America are unusually well-documented for this invasive species, there is little information about its ecology, impacts, and management options. The purpose of this research was to examine the ecology of <i>H. morsus-ranae</i> in wetlands of the upper St. Lawrence River, specifically to better understand factors influencing its abundance across different wetland zones and whether a native semi-aquatic lepidopteran that was frequently associated with the plant could serve as a potential biocontrol agent. A wetland vegetation survey revealed that <i>H. morsus-ranae</i> is one of the most dominant species in these first- and second-order tributaries, but its presence does not appear to have any relationship with native species richness or diversity. A field study of <i>H. morsus-ranae</i> conducted in tributaries and embayments of the upper St. Lawrence River suggests that this species is a successful generalist that exhibits variations in productivity, resource allocation, morphology, and reproduction. This variability likely aids its ability to establish in different wetland habitat zones (robust emergent, floating vegetation, floating-leaved vegetation) that occur along water depth and light gradients. <i>Hydrocharis morsus-ranae</i> can be categorized as a competitive, ruderal, and stress-tolerant species in wetlands, based on Grime&rsquo;s C-S-R life strategy model. A controlled, 3x3 factorial experiment was conducted to separate the effects of light and water depth on productivity and fitness of individual <i>H. morsus-ranae </i> plants. It revealed that there were interactions between the two factors and that under some light conditions, water depth was the stronger driver in plasticity and life history strategies. The information gathered for this dissertation provides a better understanding of the role of light and depth on performance of <i>H. morsus-ranae</i> and the potential use of a native insect for biocontrol. Findings may prove useful in developing management strategies for this invasive plant.</p><p>

<p> Facilitative interactions are particularly important in the climatically stressful alpine treeline ecotone (ATE), the transition zone from closed canopy forest to alpine tundra. Within some ATEs on the harsh Eastern slope in the Rocky Mountains, whitebark pine (<i>Pinus albicaulis</i>)&mdash;a foundation and keystone species&mdash;plays a central role in tree island development by facilitating the survival and growth of leeward conifers more frequently than other species. However, the structure, composition, and dynamics of ATE formation are not well known for some geographic regions of western North America, including the Greater Yellowstone Ecosystem (GYE). Although facilitative interactions are considered important to treeline community development, comparisons of biophysical attributes among the leeward microsites of nurse objects and trees are also&nbsp;lacking.&nbsp;We conducted an exploratory study of four&nbsp;treeline communities in the GYE to investigate (1) the prevalence of whitebark pine, (2) the proportional occurrence of whitebark pine as a tree island initiator, (3) whether solitary whitebark pine abundance predicts its prevalence as a tree island initiator, (4) whether whitebark pine better ameliorates local biophysical conditions relative to other plants or objects, (5) the relationship between common nurse objects and solitary/tree island initiator establishment, and (6) the presence and severity of <i> Cronartium ribicola,</i> an invasive&nbsp;pathogen that attacks and kills whitebark&nbsp;pine,&nbsp;in these communities. We found that whitebark pine is the most prevalent solitary conifer and tree island component, and initiates tree island formation in direct proportion to its abundance as a solitary tree. We also found&nbsp;that whitebark pine leeward microsites did not consistently experience the most moderate microclimate compared to spruce, fir, rock and unprotected leeward microsites; differences in microclimatic conditions by microsite type depended substantially on the general climatic conditions observed at each study area.&nbsp;Among our study areas, <i> C. ribicola</i> infection&nbsp;rates ranged from less than 1% to 18%. Our findings suggest that whitebark pine is an&nbsp;important&nbsp;treeline species in the&nbsp;Greater&nbsp;Yellowstone Ecosystem. Losses of whitebark pine from infection by <i>C. ribicola</i> will lead to&nbsp;proportional&nbsp;changes in the&nbsp;composition and structure of ATE communities in the GYE, including decline in tree island formation on the landscape.</p>