The Mid-Atlantic coastal forests in Virginia are stressed by episodic disturbance from storms associated with hurricanes and nor'easters. Using annual tree ring data, we adopt a dendroclimatic and statistical modelling approach to understand the response and resilience of a coastal pine forest to slow progressive climate change and extreme storm surge events. Results indicate that radial growth of trees in the study area is influenced by age, vigor, competition, microsite variability, and regional climatic trends, but dominated periodically by disturbance due to storm surges. We evaluated seven local storm surge events to understand the effect of storm surges associated with nor'easters and hurricanes on radial growth. A general decline in radial growth was observed in the year of the storm and three years following it, after which the radial growth starts recovering. Given the projected increase in hurricanes and storm surge severity with changing global climate, this study contributes to understanding declining tree growth response and resilience of coastal forests to past disturbances. This can help predict vegetation response patterns to similar disturbances in the future.

RATIONALE: Recent studies indicate that plants can partition electron transport through alternative oxidase (AOX) and cytochrome c oxidase (COX) in response to environmental cues, thus modulating respiratory efficiency. The ¹⁸O discrimination method necessary for measuring electron partitioning in vivo, however, has been restricted to laboratory settings due to equipment constraints. Since plants grown in more natural and variable environments may not respond as predicted by laboratory experiments, I developed a new field-compatible analytical method and then applied it to three ecophysiological studies. METHODS: To address these needs, I developed a field-compatible method in which plant tissue was incubated in 12 mL septum-capped vials for 0.5 – 3 h, after which the incubation air was transferred to 3.7 mL storage vials for subsequent measurement by mass spectrometry. I also developed mathematical tools to correct for unavoidable contamination, and to detect and address curvature in the data – whether intrinsic to the respiration or due to contamination, – and to extend the usable dynamic range of the mass spectrometer. These methods were used to investigate respiratory responses (1) in canopy trees growing across a soil nutrient gradient at the Franz Josef chronosequence, New Zealand; (2) in a nutrient manipulation experiment of Griselinea littoralis; and (3) in a long-term nutrient-, temperature-, and light manipulation at Toolik, Alaska, USA. Leaf dry matter content, specific leaf area, nitrogen (N), phosphorus (P), sugars, starch, and AOX/COX protein concentrations were also measured as explanatory variables. (Leaf Cu and Fe were measured at the Franz Josef chronosequence.) RESULTS: Discrimination values computed using my methods replicated previously reported results over a range of 10 – 31‰, with precision generally better than ±0.5‰, thus demonstrating its validity as tool for measuring respiratory electron partitioning. Foliar respiration declined with site age across the soil chronosequence, increasing with leaf N levels, r² = 0.8, but electron partitioning declined with increasing N/P, r² = 0.23. AP activity was positively correlated with leaf P, Cu, and starch, r² = 0.71. In younger soils, however, declines in respiration were attributed to declines in cytochrome pathway (CP) activity, whereas across the older sites respiration declined due to a reduction in AOX pathway (AP) activity. The Griselinia nutrient-manipulation experiment partially confirmed these results: AOX protein levels were highest in N-deficient plants rather than in plants deficient in both N and P. AP activity was very low in all leaves, however, possibly due to low illumination. In support of this claim, leaves that had developed in the sun had higher AOX/COX protein ratios than those that had developed in the greenhouse. In Griselinia roots, CP activity declined by more than half in response to nutrient deficiency, whereas AP activity was unchanged. At the Arctic site, only one species changed electron partitioning in response to nutrient addition. Betula nana, the most successful adapter to improved mineral nutrition, doubled leaf CP activity without changing AP activity. Species grown in full sun at that site also had higher AOX/COX protein ratios than those that grew in enclosures. CONCLUSIONS: This is the first study of how engagement of terminal respiratory oxidases in plants responds to multiple nutrient deficiencies, both in nature and in a controlled environment. I have uncovered some intriguing relationships, including the possible importance of N/P to electron partitioning, as well as a role for Cu. The results also suggest that electron partitioning is sensitive to plant energy balance, as suggested by the low AP activities and low AOX/COX protein ratios in shaded plants. Perhaps most significantly, the AP and CP appeared to act independently of each other, rather than through a concerted “partitioning” process. In addition to their own scientific merit, these results illustrate the value of using the new field-compatible method to conduct ecophysiological investigations of plant respiratory electron partitioning on a much large scale, and under more realistic conditions, than has been previously possible.

Spring plant phenology is often used as an indicator of a community response to climate change. Remote data and low-resolution climate models are typically used to predict phenology across a landscape; however, this tends to miss the nuances of microclimate, especially in a mountainous area with heterogeneous topography. I investigated how inter-annual variability in regional climate affects the distribution of microclimates (i.e., areas <100m2) and spring plant phenology across a 6400-hectare watershed within the Western Cascades in Oregon. Additionally, I created species-specific models of bud break at the microclimate scale, that could then be applied across a wider landscape. I found that years with warm winters, few storms and low snowpack have a homogenizing effect on microclimate and spring phenology events, and that bud break models developed at a local scale can be effectively applied across a broader landscape. This thesis includes previously unpublished coauthored material.

The purpose of this thesis is to develop a mathematical approach and associated software implementation for deconvolution of two-dimensional Transmission Electron Microscope (TEM) images. The focus is on TEM images of weakly scattering amorphous biological specimens that mainly produce phase contrast. The deconvolution is to remove the distortions introduced by the TEM detector that are modeled by the Modulation Transfer Function (MTF). The report tests deconvolution of the TEM detector MTF by Wiener _ltering and Tikhonov regularization on a range of simulated TEM images with varying degree of noise.The performance of the two deconvolution methods are quanti_ed by means of Figure of Merits (FOMs) and comparison in-between methods is based on statistical analysis of the FOMs.

Long-Term Socio-Ecological Research (LTSER) is an inter- and transdisciplinary research field addressing socio-ecological change over time at various spatial and temporal scales. In the Austrian Eisenwurzen region, an LTSER platform was founded in 2004. It has fostered and documented research projects aiming at advancing LTSER scientifically and at providing regional stakeholders with relevant information for sustainable regional development. Since its establishment, a broad range of research activities has been pursued in the region, integrating information from long-term ecological monitoring sites with approaches from social sciences and the humanities, and in cooperation with regional stakeholders. Based on the experiences gained in the Eisenwurzen LTSER platform, this article presents current activities in the heterogeneous field of LTSER, identifying specific (inter-)disciplinary contributions of three research strands of LTSER: long-term ecological research, socio-ecological basic research, and transdisciplinary research. Given the broad array of diverse contributions to LTSER, we argue that the platform has become a relevant "boundary organization", linking research to its regional non-academic context, and ensuring interdisciplinary exchange among the variety of disciplines. We consider the diversity of LTSER approaches an important resource for future research. Major success criteria of LTSER face specific challenges: (1) existing loose, yet stable networks need to be maintained and extended; (2) continuous generation of and access to relevant data needs to be secured and more data need to be included; and (3) consecutive research projects that have allowed for capacity building in the past may be threatened in the future if national Austrian research funders cease to provide resources.

No description available.

When we look at the eld of robotics we nd that exist a lot of types of robots. Some of tham use location navigation and global navigation for their work. This work aims to map options of location navigation and description of basic technique which used. Especially, we will deal with algorithms which work with optical sensors, for example camera, stereocamera or laser which scan medium. Practise section this work is focused on the proposal and implementacion algorithm which working with local navigation for robot's return to the starting position. All this work is connecting with tracked robot which formed in the framework one of project realization at Faculty of information technology.

Located at the interfaces of terrestrial and marine environments, coastal habitats are inherently vulnerable to the effects of global change. Barrier island systems in particular serve not only as protective buffers against storm events, but also as sentinel ecosystems for observation of the impacts of sea level rise, and of increasing storm frequency and intensity. In the mid-Atlantic region, shrub thickets of Morella species compose the dominant forest community. The often monospecific nature of these plant community assemblages is advantageous to ecological studies and cross-scale applications; the relatively low diversity facilitates transitions between scales. My objective was to investigate the distribution and community roles of lianas in mid-Atlantic barrier island forest communities. I quantified environmental variables at two barrier habitats with differing site management histories and corresponding topography, and found that abiotic factors affected distributions of woody species, which subsequently affected vine species distributions. Some association of prevalent vine species with the common woody plants Prunus serotina and Morella cerifera was observed, though neither vines nor woody species demonstrated significant species-specific phytosociological associations. Vines demonstrated a long-lasting effect of arresting or delaying succession, and are potentially responsible for the lack of redevelopment of mature maritime forest at these sites. At Hog Island, Virginia, remotely-sensed data were utilized to determine the three-dimensional structural effects of vine infiltration in woody canopies. Vines were found to reduce canopy height and depth, and increase density, short-term diversity, and light-intercepting biomass. Significant vine infiltration can accelerate senescence of shrub thickets, but often results in persistent tangled masses of vegetation which reduce recruitment of later-successional species. These effects may represent long-term, lasting impacts of vine establishment and expansion in these habitats, affecting community succession towards diverse and stable maritime forest, and significantly altering resource dynamics in these sensitive ecosystems.

Increased nutrient availability globally has the potential to affect community functional composition of plants in nutrient limited environments, such as coastal grassland systems. Stability of these systems are threatened worldwide by urbanization, as well as effects of sea level rise and increased frequency and intensity of storms, and atmospheric N deposition, associated with climate change. Annual net primary productivity (ANPP), species composition, and functional traits (community weighted specific leaf area (CWSLA), leaf area index (LAI), growth form and photosynthetic pathway) were measured across four treatments to assess multiple resource limitation of nitrogen (N) and phosphorus (P) and functional community response in a coastal grassland on Hog Island, VA within the Virginia Coast Reserve, Long Term Ecological Research Network (LTER) applied at a rate of 10 g m-2 yr-1 Nutrient enrichment did not alter species diversity or richness. ANPP was highest in plots receiving any type of nitrogen enrichment, and was higher than expected of low nutrient systems. CWSLA was significantly higher in NP plots, and was lower than other grasslands. P treatments were not significantly different from controls. Graminoid species, specifically C4 species responded with higher ANPP than C3 forbs or graminoids within treatments. Evidence of synergistic NP effects were seen on community level resource allocation and leaf construction, but no significant species changes occurred over a 1-year time span. These results have expanded the knowledge of functional response to increased nutrient availability in an understudied, coastal grassland, which are at high risk to being lost to sea level rise and anthropogenic development and inform community assembly processes in stressful environments.

Montane meadows comprise less than 5% of the landscape of the western Cascades of Oregon, but they provide habitat for diverse species of plants and pollinators. Little is known about plant-pollinator network structure at these sites. This study quantified plant-pollinator interactions over the summer of 2011, based on six observations of 10 permanent subplots in 15 meadows, stratified by size and isolation. The study examined (1) relationships between richness and abundance of flowers, pollinators, and interactions; (2) distribution of abundance and richness of flowers, pollinators, and interactions with regards to surrounding meadow habitat; (3) change in flower and pollinator abundance over the season; (4) factors associated with the presence of various guilds of pollinators; and (5) the structure of plant-pollinator networks. The study showed that (1) richness of pollinators increased 2x faster than richness of flowers with increased abundance; (2) density of flowers and interactions was positively correlated with meadow size and diversity of pollinators and interactions were both correlated with surrounding habitat at two spatial scales; (3) peak flower abundance coincided with or preceded peaks in pollinator populations; (4) abundance of three guilds of bees exhibited different patterns of association to surrounding habitat and meadow soil moisture corresponding to various dispersal potential and phenology of guild species; and (5) the number of network pairings for plants and pollinators increased with increasing species richness of potential interaction partners and all networks were found to be significantly nested. Results of this study indicate that plant-pollinator networks are complex assemblages of species, in which spatial and temporal patterns of habitat affect species composition and network structure. In particular, flower and pollinator abundance and richness are depressed in small and isolated meadows. Significant nestedness emerged as a pattern of network level organization across the study meadows. / Graduation date: 2013