<p>Under the increasing threat of climate change, it is imperative to understand the impact that environmental phenomena have on the demography and behavior of natural populations. In the last few decades an ever increasing body of research has documented dramatic changes in mortality rates and breeding phenology for a large number of species. A number of these have been attributed to the current trends in climate change, which have been particularly conspicuous in bird populations. However, datasets associated to these natural populations as well as to the environmental variables that affect their biology tend to be partial and incomplete. Thus, ecological research faces the urgent need to tackle these questions while at the same time develop inferential models that can handle the complex structure of these datasets and their associated uncertainty. Therefore, my dissertation research has focused on two main objectives: 1) to understand the relationship that demographic rates and breeding phenology of a colony of seabirds has with the environment in the context of climate change; and 2) to use and develop models that can encompass the complex structure of these natural systems, while also extending the process not only to inference but to building predictions. I divided this work in three research projects; for the first one I developed a hierarchical Bayesian model for age-specific survival for long lived species with capture-recapture data that allows the use of incomplete data (i.e. left-truncated and right-censored), and builds predictions of years of birth and death for all individuals while also drawing inference on the survivorship function. I compared this method to more traditional ones and address their limitations and advantages. My second research chapter makes use of this method to determine the age-specific survivorship of the Dry Tortugas sooty tern population, and explores the effect of changes in sea surface temperature on their cohort mortality rates. Finally, my third research chapter addresses the dramatic shift in breeding season experienced by the Dry Tortugas sooty tern colony, the most unprecedented shift reported for any bird species. I explore the role of climatic and weather variables as triggering mechanisms.</p> / Dissertation

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<p>This dissertation examines the processes that generate phenotypic variation in life cycles in seasonal environments. Collectively, a life cycle describes the stages an organism passes through during a generation. The timing, or phenology, of these transitions is often influenced by both environmental and allelic variation. Using the model organism Arabidopsis thaliana and both empirical and modeling approaches, I examine how correlations between life-cycle transitions, environment-dependent allelic effects, and epistasis generate patterns of life-cycle variation both within and between generations. In my first chapter, I use experiments to determine that many combinations of genetic, environmental, and developmental factors can create similar germination phenotypes, that maternal effects can influence phenotypes more than genetic differences, and that cross-generational effects can reduce variation in germination timing despite variation in flowering and dispersal time. In my second chapter, I use a modeling approach to consider the entire life cycle. I find that environmental variation is a major driver of phenotypic variation, and that considering the known geographic distribution of allelic variation across the range improves the match of model predictions to phenotypes expressed in natural populations. Specifically, variation in dormancy generated in the previous generation is predicted to cause life-cycle differences within a location, and the geographic distribution of allelic variation in dormancy interacts with local climatic environments to canalize an annual life history across the range. Finally, I test if allelic and environmental variation that affects early life stages can influence the environment experienced during reproduction. This environment determines both the time available for reproduction and the environment experienced during senescence. By implementing simple survival rules for flowering plants in the model, I show that time available for a plant to reproduce depends on earlier phenological traits and varies widely from year to year, location to location, and genotype to genotype. If reproductive trade-offs that underlie the evolution of senescence are environmentally sensitive, these results suggest that genetic variation in earlier life-stage transitions might shape senescence rates and whether they are environmentally responsive. In sum, my dissertation demonstrates the importance of pleiotropy, environment-dependent allelic expression, and epistasis in defining life-cycle variation, and proposes a novel way of predicting these relationships and complex life cycles under seasonal conditions.</p> / Dissertation

Droughts are a recurrent part of our climate, and are still considered to be one of the most complex and least understood of all natural hazards in terms of their impact on the environment. In recent years drought has become more common and more severe across the world. For more than a decade, the US southwest has faced extensive and persistent drought conditions that have impacted vegetation communities and local water resources. The focus of this work is achieving a better understanding of the impact of drought on the lands of the Hopi Tribe and Navajo Nation, situated in the Northeastern corner of Arizona. This research explores the application of remote sensing data and geospatial tools in two studies to monitor drought impacts on vegetation productivity. In both studies we used land surface phenometrics as the data tool. In a third related study, I have compared satellite-derived land surface phenology (LSP) to field observations of crop stages at the Maricopa Agricultural Center to achieve a better understanding of the temporal sensitivity of satellite derived phenology of vegetation and understand their accuracy as a tool for monitoring change. The first study explores long-term vegetation productivity responses to drought. The paper develops a framework for drought monitoring and assessment by integrating land cover, climate, and topographical data with LSP. The objective of the framework is to detect long-term vegetation changes and trends in the Normalized Difference Vegetation Index (NDVI) related productivity. The second study examines the major driving forces of vegetation dynamics in order to provide valuable spatial information related to inter-annual variability in vegetation productivity for mitigating drought impacts. The third study tests the accuracy of remote sensing-derived LSP by comparing them to the actual seasonal phases of crop growth. This provides a way to compare and validate the various LSP algorithms, and more crucially, helps to characterize the remote sensing-based metrics that contrast with the actual biological phenophases of the crops. These studies demonstrate how remote sensing data and simple statistical tools can be used to assess drought effects on vegetation productivity and to inform about land conditions, as well as to better understand the accuracy of satellite derived LSP.

Synoptic global remote sensing provides a multitude of land surface state variables. The continuous collection, for more than 30 years, of global observations has contributed to the creation of a unique and long term satellite imagery archive from different sensors. These records have become an invaluable source of data for many environmental and global change related studies. The problem, however, is that they are not readily available for use in research and application environment and require multiple preprocessing. Here, we looked at the daily global data records from the Advanced Very High Resolution Radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS), two of the most widely available and used datasets, with the objective of assessing their quality and suitability to support studies dealing with global trends and changes at the land surface. Findings show that clouds are the major data quality inhibitors, and that the MODIS cloud masking algorithm performs better than the AVHRR. Results show that areas of high ecological importance, like the Amazon, are most prone to lack of data due to cloud cover and aerosols leading to extended periods of time with no useful data, sometimes months. While the standard approach to these challenges has been compositing of daily images to generate a representative map over a preset time periods, our results indicate that preset compositing is not the optimal solution and a hybrid location dependent method that preserves the high frequency of these observations over the areas where clouds are not as prevalent works better. Using this data quality information the Vegetation Index and Phenology (VIP) Laboratory at The University of Arizona produced over 30 years of seamless sensor independent record of vegetation indices and land surface phenology metrics. These data records consist of 0.05-degree resolution global images for daily, 7-days, 15-days and monthly temporal frequency. These sort of remote sensing based products are normally made available through the internet by large data centers, like the Land Processes Distributed Active Archive Center (LP DAAC), however, in this project an online tool, the VIP Data Explorer, was developed to support the visualization, exploration, and distribution of these Earth Science Data Records (ESDRs) keeping it closer to the data generation center which provides a more active data support and distribution model. This web application has made it possible for users to explore and evaluate the products suite before download and use.

3 pp. / Phenology is defined and described in terms of how we use observations in education and research. Suggestions for implementing phenology lessons using examples from 4-H youth development and Master Gardener and citizen science training.

Buffelgrass (Cenchrus ciliaris L.) is an invasive, perennial, C₄ bunchgrass. Buffelgrass has a rapid invasion rate, a tendency to displace native vegetation, and presents a fire risk to native plant communities, adjacent developed areas and their associated infrastructure. Mechanical control is impractical and unable to keep pace with regional spread. Chemical control has offered the most promise for successful and cost-effective management on a regional scale. The predominant herbicide used to control buffelgrass is glyphosate, which requires active vegetative growth when applied for optimum uptake and translocation to meristematic tissue. The timing and duration of active growth is difficult to predict. In this dissertation I addressed three related topics to improve effectiveness of buffelgrass management in the Sonoran Desert. First, I used digital time-lapse photography and weather data to predict the timing and length of future active growth based on day of year and antecedent weather at three sites in the Sonoran Desert near Tucson, AZ that were representative of habitats currently infested by buffelgrass in the region. I was able to correctly predict greenness above or below a threshold of herbicide susceptibility at 81 to 95% for a basin floor site and at 61-88% for slope sites. Second, I evaluated the effects of different rates of two herbicides (imazapic and clethodim), alone or in combination with different rates of glyphosate, for pre- (imazapic only) and postemergence control of buffelgrass. I found a minimum glyphosate application rate of 2.52 kg ae ha⁻¹ glyphosate consistently killed mature buffelgrass plants; clethodim at had no effect on mature buffelgrass; and imazapyr was successful in killing mature plants when applied during the dormant season at 0.56 kg ae ha⁻¹ and provided preemergence control. Imazapic severely damaged but did not kill mature buffelgrass plants at the maximum label rate of 0.21 kg ae ha⁻¹. Finally, we evaluated results from a helicopter broadcast herbicide application trial conducted in the Tucson Mountains. We demonstrated that most species and life forms were less affected than buffelgrass to glyphosate deposition rates achieved in the study, but asserted that procedural changes were necessary to achieve effective buffelgrass control.

Tyrimų pagrindimas. Paprastoji eglė yra svarbi ūkinė rūšis Lietuvoje. Kilmių perkėlimas ir tolesnė selekcija gali ženkliai padidinti genetinę naudą gautiną iš p . eglės ūkinės paskirties medynų. Tuo tikslu, reikia informacijos apie genetinius skirtumus ir jų kitimo dėsningumus tarp p. eglės populiacijų perspektyviame introdukcijai Baltijos regione. Tyrimo tikslas- palyginti paprastosios eglės Baltijos regiono kilmių palikuonių adaptacinių, stiebo kokybės ir gyvybingumo požymių geografinio kintamumo dėsningumus bei kilmių perkėlimo ūkinę naudą bandomuosiuose želdiniuose. Objektas – 2001 m. įveisti paprastosios eglės Baltijos regiono kilmių palikuonių bandomieji želdiniai Kazlų Rūdos MMU (85 kilmės, po 50 kiekvienos kilmės medelių). Metodai – tyrimo metu buvo įvertintas medelių aukštis ir stiebo kokybė, nustatyta pumpurų sprogimo klasė, bei atlikta šių duomenų statistinė analizė. Rezultatai. Iš pietų į šiaurę perkeltų kilmių medeliai buvo aukštesni, geresnės stiebo kokybės ir vėliau pradėjo sezoninį augimą nei šiaurinių kilmių medeliai. Ypač mažu produktyvumu ir prasta stiebo kokybe pasižymėjo šiauriausios šiame bandyme pietų Suomijos kilmės, o šiaurinės Lenkijos kilmių medeliai produktyvumu lenkė vietinės kilmės medelius. Tai paaiškintina santykinai stipresniais šalnų pakenkimais, dėl ankstyvesnės šiauresnių kilmių sezoninio augimo pradžios ir mažesniu medeliu aukščiu dėl santykinai ankstesnės augimo pabaigos. Minėtų požymių geografinis kintamumas yra palaipsniui... [toliau žr. visą tekstą] / Background. Norway spruce is an imprint commercial forest tree specie sin Lithuanian. Provenance transfer and further breeding may markedly rise the benefit from commercial forests of Norway spruce,. For this purpose, there is a need of information on genetic variation and its geographical patters among Norway spruce provenances within the Baltic sea region of interest for introduction to Lithuania an don the benefit of the transfer itself. Objectives of the study are to compare the patterns of geographical variation among Baltic Norway spruce provenances in adaptive traits and to assess benefit of provenance transfer in the experimental plantation. The test. The study was carried out in an experimental plantation of Baltic Norway spruce provenances established in 2001 in Kazlu Ruda MMU (85 provenances of 50 trees each). Methods. Height, stem quality and stage of budburst in spring of the provenances were measured in the experimental plantation and statistical analysis methods were used to present the data. The results. The results showed that trees of the southern provenances were taller of better stem quality and later growth start in spring than trees of northern provenances. Trees of the most northern in this trial Finnish and Swedish provenances performed extremely poorly. Northern Polish provenances were more productive than the tree of the local origin. This result may be a consequence of spring frost damage of early flushing trees. The trees of northern... [to full text]

This research investigated the phenology of the striped flea beetle (Phyllotreta striolata (Fabricius) (SFB) and crucifer flea beetle (Phyllotreta cruciferae (Goeze)) (CFB), and examined the efficacy and the persistence of biological activity of the reduced-risk insecticides cyantraniliprole, clothianidin, and thiamethoxam applied as seed treatments to spring canola. Yellow sticky cards were placed around field perimeters in order to assess if CFB and SFB have synchronous phenology. It was found that CFB and SFB have largely asynchronous populations in southern Ontario. In laboratory bioassays, while flea beetle control with cyantraniliprole was comparable to that provided by thiamethoxam or clothianidin at the cotyledon stage, control did not persist through the 1st and 2nd leaf stages. Thiamethoxam and clothianidin both provided moderate control of flea beetles in both 1st and 2nd leaves. Field studies suggested that cyantraniliprole may offer control of flea beetles comparable to that provided by thiamethoxam and clothianidin. / E.I. DuPont Canada Co.

Kiekvienais metais, augalams žydint, išbyra žiedadulkių. Augalai skirtingu metu subrandina žiedadulkes, tačiau ir tos paties rūšies žiedadulkėms būdingi fiksavimo kitimai. Žiedadulkių sklaidos tyrimams yra svarbūs ir fitofenologiniai duomenys, todėl detali šių duomenų analizė yra būtina atliekant žiedadulkių kiekių, sezonų trukmės įvertinimus. / Every year, when plants bloom some pollen is spread. Plants mature a different quantity of pollen in different time, though fixing changes are typical even to the pollen of the same species. Phytophenological data is also important to the investigation of the pollen dispersion., thus the detailed analysis of this data is essential for the evaluation of the pollen quantity and duration of the seasons.