The American beaver, the largest rodent of North America, is distributed in ponds, lakes, and streams from Alaska to northern Mexico. This semi-aquatic mammal is considered an ecosystem engineer because beavers modify the landscape by cutting trees and by creating dams and ponds that have important effects on the aquatic community structure, providing habitat for aquatic invertebrates, fish, and birds. The American beaver has played an important socioeconomic role in the history of North America due to beavers' fur value, which caused the near extirpation of this mammal at the beginning of the 1900s due to overharvest by early Europeans. Because of the highly specific habitat requirements of beavers, this mammal also suffers the effects of habitat loss in some areas where riparian ecosystems are now scarce. My objectives in this study were to assess how climatic and geological events affected the current distribution of the American beaver in North America, and how the management actions to restore and control beaver populations have affected the genetic structure and conservation of beaver populations. Specifically, I addressed four aspects of the management and conservation genetics of the beaver: 1) a literature review of the management of beavers in the past 100 years; 2) the development of novel microsatellite DNA markers to address the population genetic structure aspects of the study; 3) the use of these microsatellite DNA markers to assess genetic diversity of current populations of beavers and to detect past population bottlenecks; and 4) the use of two mitochondrial DNA genes to resolve the current phylogeography of the American beaver in order to better understand how historical factors have affected the beaver's current distribution and genetic structure in North America. The results from this study provide information of the effects that management actions and climatic events can have on the genetic structure of beavers. This information can be used by wildlife biologists, and land managers, to develop future strategies for management and conservation of the American beaver.

Magistro darbe tyrinėjama, kaip Lietuvos ir kai kurių užsienio valstybių bendrojo lavinimo mokyklose yra mokoma informatikos, aiškinamasi, koks požiūris į šią mokomąja discipliną, kurie veiksniai tai įtakoja. Tyrimui pasirinktas įdomesnis kelias – naudojamasi informatikos ir kompiuterinio lavinimosi varžybomis „Bebras“, kurios vyksta daugiau kaip dešimtyje valstybių. Palyginti 2008–2010 metais Lietuvoje vykusių „Bebro“ varžybų užduočių rinkiniai pagal įvairius informatikos konceptus. Pasinaudojus 2010 metais Lietuvos „Bebro“ varžybose dalyvavusių mokinių rezultatų duomenimis bei pritaikius atitinkamus matematinius užduočių vertinimo modelius, buvo įvertinta užduočių rinkinio informacinė funkcija, kuri leidžia parinkti tinkamiausias užduotis atitinkamam mokinių žinių lygiui. Mokinių informatikos žinių lygis neatsiejamas nuo informatikos pagrindų, kurie formuojasi laikui bėgant, kai mokinys gauna tinkamą informaciją ne tik per informatikos ar informacinių technologijų pamokas, bet ir kai mokytojai informacines ir komunikacines priemones taiko per kitų dalykų pamokas. Darbe apskaičiuoti užduočių sunkumo koeficientai, kurie palyginti su užduočių sunkumo lygiais, kuriuos priskyrė uždavinių sudarytojai ar vertintojai. Taip pat nustatyti užduočių skiriamosios gebos indeksai, kurie nustato, kiek gerai užduotis atskiria geresnius mokinių darbus nuo blogesnių tikrinamo dalyko atžvilgiu. Tyrimo rezultatai svarbūs tiek mokytojams, kurie turi įtakos mokinių informatikos pagrindų... [toliau žr. visą tekstą] / In this master thesis, computer science curriculum in compulsory school of Lithuania and other foreign countries are reviewed. Data of "Beaver" information technology contest, which is organized in more than ten countries, has been selected as a more attractive way to imlement this study. The comparisons of tasks sets in Lithuanian “Beaver” competition in 2008 – 2010 according to informatics concepts are presented. In this thesis, there was assessed information function of tasks set by using data of pupils’ results. The data of results were obtained from Lithuanian competition of “Beaver” in 2010. Information function allows choosing the best tasks for due ability level of pupils. Pupils’ abilities level of computer science is inseparable from informatics fundamentals, which is forming over time when pupils get the right information about informatics fundamentals during the computers science lesson, or when their teachers use information and communication technologies. The difficulty parameters of tasks, and discriminations parameters of tasks, which describe how well an item can differentiate between examinees having abilities below the item location and those having abilities above the item location, are calculated. The results of this study are important for teachers, which influence formation of informatics fundamentals of pupils, as well as for experts and creators of competition tasks, because for them it is important the right and purposeful introduction to computer... [to full text]

The surveillance and control of introduced species has become an increasingly important, yet often controversial, form of environmental management. I investigate why and how introduced species management is initiated; whether, why and how it is contested; and what relations and outcomes emerge ‘in practice’. I examine how introduced species management is being done in the United Kingdom through detailed social scientific analyses of the processes, practices, and disputes involved in a series of management case studies. First, I demonstrate how some established approaches to the design and delivery of management initiatives can render them conflict-prone, ineffective and potentially unjust. Then, examining a disputesurrounding a state-initiated eradication of monk parakeets (Myiopsitta monachus), I show why and how ‘parakeet protectors’ opposed the initiative. I identify the significance of divergent evaluations of the risks posed by introduced wildlife; personal and community attachments between people and parakeets; and campaigners’ dissatisfaction with central government’s approach to the issue. By following the story of an unauthorised (re)introduction of Eurasian beavers (Castor fiber) to England, I show how adiverse collective has, at least temporarily, been united and empowered by a shared understanding of beavers as ‘belonging’ in the UK. I consider how nonhuman citizenship is socio-politically negotiated, and how the beavers have become enrolled in a ‘wild experiment’. Finally, through a multi- sited study of grey squirrel (Sciuruscarolinensis) control initiatives, I find important variations in management practitioners’ approaches to killing squirrels, and identify several ‘modes of killing’ that comprise different primary motivations, moral principles, ultimate aims, and practical methods. I identify multiple ways in which people respond and relate to introduced wildlife, and demonstrate how this multiplicity produces both socio-political tensions and accords. Furthermore, throughout this thesis I make a series of propositions for re-configuring the management of introduced species in ways that explicitly incorporate inclusive, constructive, and context-appropriate socio-political deliberations into its design and implementation.

Managed forest landscapes in Sweden are dominated by boreal coniferous forest and are deficient in broad-leaved trees. Both beavers (Castor fiber) and ungulate browsers prefer broad-leaved trees to conifers, and the interaction between multiple herbivores may have a considerable impact on the recruitment of deciduous trees in riparian areas. To evaluate the relative importance of beavers and browsers on tree recruitment, I conducted an inventory of broad-leaved tree species at five beaver sites in Färnebofjärden National Park, Sweden. At each site, five transects were established perpendicular to the shoreline in the riparian zone, resulting in a grid of 35 sample plots at each beaver site. Foraging activity of both beavers and browsers (e.g. ungulates) was concentrated to a narrow band in the riparian zone and there was a decrease in the proportion of beaver-cut and browsed trees further away from the shoreline. Beavers preferred birch (Betula spp.) and grey willow (Salix cinerea) while browsers preferred oak (Quercus robur). Beavers targeted larger trees while browsers targeted seedlings <1 cm in diameter. Old-growth trees of high conservation value, such as aspen (Populus tremula) and birch, are at risk to be cut by beaver, yet long-term protection of broad-leaved stands requires a shift in focus towards strategies that enhance tree recruitment by considering and mitigating pressure from multiple herbivores. / Svenska skogslandskap domineras av boreal barrskog med en brist på lövträd. Både bäver (Castor fiber) och betande klövvilt föredrar lövträd framför barrträd, och interaktionen mellan dessa herbivorer kan ha en betydande påverkan på föryngring av lövträd i strandnära skogar. För att utvärdera den relativa betydelsen av bävrar och betare på trädföryngring så genomförde jag en inventering av lövträdsarter och betestryck vid fem bäverlokaler i Färnebofjärden Nationalpark, Sverige. Vid varje bäverlokal lades fem transekter i rät vinkel mot strandkanten i den strandnära zonen, med provrutor var femte meter längs varje transekt, vilket resulterade i ett nätverk av 35 provrutor vid varje lokal. Både bävrars och betares (dvs. klövvilts) födosökande var begränsat till ett smalt band längs strandkanten, och andelen bävergnagda och betade trädstammar minskade med ökat avstånd från strandkanten. Bäver föredrog björk och gråvide medan betare föredrog ek. Bäver föredrog större träd medan betare föredrog groddplantor <1 cm i diameter. Gamla lövträd som är viktiga att bevara, såsom asp och björk, hotas av bäveraktivitet, men långsiktigt bevarande av lövträdsbestånd kräver ett fokus på strategier som främjar trädföryngring, bland annat genom att beakta och begränsa den sammantagna påverkan av olika herbivorers betning.

Initial soil surveys are incomplete for large tracts of public land in the western USA. Digital soil mapping offers a quantitative approach as an alternative to traditional soil mapping. I sought to predict soil classes across an arid to semiarid watershed of western Utah by applying random forests (RF) and using environmental covariates derived from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and digital elevation models (DEM). Random forests are similar to classification and regression trees (CART). However, RF is doubly random. Many (e.g., 500) weak trees are grown (trained) independently because each tree is trained with a new randomly selected bootstrap sample, and a random subset of variables is used to split each node. To train and validate the RF trees, 561 soil descriptions were made in the field. An additional 111 points were added by case-based reasoning using aerial photo interpretation. As RF makes classification decisions from the mode of many independently grown trees, model uncertainty can be derived. The overall out of the bag (OOB) error was lower without weighting of classes; weighting increased the overall OOB error and the resulting output did not reflect soil-landscape relationships observed in the field. The final RF model had an OOB error of 55.2% and predicted soils on landforms consistent with soil-landscape relationships. The OOB error for individual classes typically decreased with increasing class size. In addition to the final classification, I determined the second and third most likely classification, model confidence, and the hypothetical extent of individual classes. Pixels that had high possibility of belonging to multiple soil classes were aggregated using a minimum confidence value based on limiting soil features, which is an effective and objective method of determining membership in soil map unit associations and complexes mapped at the 1:24,000 scale. Variables derived from both DEM and Landsat 7 ETM+ sources were important for predicting soil classes based on Gini and standard measures of variable importance and OOB errors from groves grown with exclusively DEM- or Landsat-derived data. Random forests was a powerful predictor of soil classes and produced outputs that facilitated further understanding of soil-landscape relationships.

Beaver dams alter streams characteristics in a way that promotes the diversity of aquatic species and provides a wide distribution of temperatures within beaver ponds. In order to quantify the spatial distribution of these temperatures, a process-based temperature model was developed for a beaver pond in Northern Utah. This model provided insight into the processes and characteristics that are driving these temperatures. Solar radiation is one of these processes that is often the primary driver of stream temperature. There is a need to develop methods to measure the fate of solar radiation within the water to better represent solar radiation within stream temperature models. Black-body pyranometers are instruments that measure solar radiation in air, but require corrections for use underwater. Studies were conducted investigating methods for correcting these instruments. Based on the results of these studies it is suggested that these corrections are dependent on the spectrum of the light source and that the instrument needs further corrections when the light source is measured from different angles; therefore there is a need for further investigation into pyranometer corrections in order to measure the fate of solar radiation in natural water bodies. Combined, this research provides methods and suggests additional research opportunities for more accurately quantifying and predicting stream temperatures for waters impacted by beaver.

Beavers were virtually extirpated from North America during the fur trade, but populations have since recovered. Dams built by recolonizing beaver alter stream habitat by forming deep, slow ponds within the streams. Such changes to the habitat is likely to have consequences for organisms such as macroinvertebrates and fish. The objective of this study was to identify the differences in the macroinvertebrate and trout community in beaver ponds and lotic (e.g. flowing reaches of a stream) reaches in tributaries to the Logan River in northeastern Utah. The macroinvertebrate community of beaver ponds had fewer species, fewer numbers, and lower biomass of macroinvertebrates compared to lotic reaches. Macroinvertebrates that consume leaf litter and predators that prey on other macroinvertebrates characterized beaver pond macroinvertebrate communities. In contrast, lotic reaches contained macroinvertebrates that consume algae and feed on particles floating through the water column. Macroinvertebrates in lotic reaches were morphologically adapted to cling to rocks in the streamflow, while those in beaver ponds were adapted to living within the fine sediment. Bonneville cutthroat trout collected from lotic reaches were larger than those collected from beaver ponds, while the opposite was true for brown trout collected from lotic reaches. I also found that short-term and long-term diets of both brown trout and Bonneville cutthroat trout were similar between trout caught in beaver pond and lotic reaches. Finally, I found that growth rates of trout were also similar between the two habitats. In conclusion, the structure and function of macroinvertebrates, which are dependent on small-scale habitat features, were more affected by inclusion of beaver ponds to the stream network. Conversely, trout collected from beaver ponds and lotic regions were similar in growth and diet. Considering that beavers are used as a common restoration tool, further studies on the effects of beaver on stream communities is essential.

The distribution of Lahontan cutthroat trout Oncorhynchus clarki henshawi was assessed in a high-desert stream in southeastern Oregon where beaver Castor canadensis are abundant. Longitudinal patterns of beaver ponds, habitat, temperature, and Lahontan cutthroat trout age group distribution were identified throughout Willow Creek. Three distinct stream segments were classified based on geomorphological characteristics. Four beaver-pond and four free-flowing sample sections were randomly located in each of the three stream segments. Beavers substantially altered the physical habitat of Willow Creek increasing the depth and width of available habitat. In contrast, there was no measurable effect on water temperature. The total number of Lahontan cutthroat trout per meter was significantly higher in beaver ponds than free-flowing sections. Although density (fish/m��) showed no statistically significant (P<0.05) increase, values in beaver ponds were two-fold those of free-flowing sections. Age-1 and young-of-the-year trout were absent or in very low numbers in lower Willow Creek because of elevated temperatures, but high numbers of age-2 and 3 (adults) Lahontan cutthroat trout were found in beaver ponds where water temperatures reached lethal levels (>24��C). Apparently survival is greater in beaver ponds than free-flowing sections as temperatures approach lethal limits. / Graduation date: 2003

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xii, 170 p. : ill. (some col.), maps (part col.). Includes abstract. Includes bibliographical references (p. 112-116).

Tyrimo objektas – Pagramančio regioninio parko bebrų populiacija. Pagrindinis tyrimų vienetas – bebravietė. Tyrimo tikslas – ištirti bebrų pasiskirstymą atskiruose biotopuose ir įvertinti jų įtaką aplinkai. Tikslui įgyvendinti buvo iškelti uždaviniai: Nustatyti bebrų gausą atskiruose biotopuose ir įvertinti jų įtaką aplinkai Nustatyti bebrų pasiskirstymą Tyrimų metodai: literatūros loginės analizės, tiesioginis bebrų stebėjimas, jų veklos žymių analizės. Buvo naudojami tokie tyrimo duomenys: kartografinė medžiaga, bebrų apskaita, bebrų poveikio aplinkai vertinimas. Mokslinis tiriamasis darbas buvo atliktas 2007 metų pavasarį, nutirpus sniegui ir susinormalizavus vandens lygiui (balandžio mėnesį). Pirminiai duomenys apie bebraviečių lokalizacijas buvo renkami pasitelkiant miškininkų, medžiotojų pateiktą informaciją. Ši informacija buvo tikrinama natūroje bei ieškomos naujos nežinomos bebravietės. Kiekviena bebravietė esanti tiriamoje teritorijoje buvo užregistruota. Rezultatai: Nustatyta, kad Pagramančio regioniniame parke daugiausia bebrai įsukuria miškuose ( 53 % ), melioracijos kanaluose ( 70,6 % ) ir sudaro mažas šeimas ( 35 % ). Šioje teritorijoje daugiausia jaunų ar vidutinio amžiaus bebraviečių, pilnos sudėties šeimų ( 58,8 % ). Pagal patvankos pobūdį teritorijoje visos bebravietės buvo su užtvankom, kadangi ežerų čia nėra, o bebrai gyvena tik melioracijos kanaluose ir upėse. / The subject of reserach – beavers population in Pagramantis regional park. The main fugure – beavers lodge. The point of reserach – to analyse beavers distriction in the separate ecosystems and set their effect to landscape. To implement the main point I set a tasks: To set plenty of beavers in different ecosystems and set their effect to landscape. To set distribution of beaver. The method of reserch. Logical analysis of literature, ostensible observation of beaver, wheir work signs analysis. Where were usable material of research: cartografic material, record of beaver, their effect to landscape. Scientific research project was made in 2007 spring, when snow was numbed and water level was normalized ( in April ). Incomposite data about localization of lodge was elected by invoking information of foresters and hunters. This information were cheking in nature and where were seeking new and undiscovered lodge of beavers. Each of lodge in searching teritory were registered. Results: Finding that in Pagramantis regional park beavers settle down in forests ( 53 % ), in melioration channels ( 70,6 % ) and beavers making a small familys ( 35 % ). In this territory for the most part are young and middle-aged lodges, full compositios of family ( 58,8 % ). By the tone of lift in territory all the lodges were with dams, whereas where no lakes beavers are living in melioration channles and rivers.