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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Assessing the relationships between pollinator-friendly plantings and birds, bats and white-tailed deer on farms in the Coastal Plain of Virginia and Maryland

Berge, Earle Johnathan 30 November 2020 (has links)
Pollinator-friendly wildflower and native grass plantings are increasingly incentivized by state and federal agencies to improve ecosystem services provided by pollinating insects on farmland. However, the potential ecosystem service benefits, or even disservices, of pollinator-friendly plantings relative to wildlife, such as resident, migratory, and nesting birds (e.g., wild turkey (Meleagris gallopavo)), resident and migratory bats, and white-tailed deer (Odocoileus virginianus) are of interest to both landowners and conservation managers. First, we studied bird species diversity, presence, density, and nesting on farms planted with and without pollinator-friendly plantings to evaluate the potential value of these plantings to bird-related values, such as cultural, recreational, and pest-regulating ecosystem services. Second, we quantified bat relative activity through recorded echolocation calls and explored how relative nightly activity varied across common cover types on a farm, by survey year, and by maternity (May-August) versus non-maternity season (September-April). Third, we determined whether white-tailed deer and wild turkey camera trap success and occupancy differed between farms with and without pollinator-friendly farmscaped plots, evaluated along with their relationships to percent cover of natural, developed, crop, and water habitats within 1 km of surveyed farms. We conducted bird point counts across 20 farms on the Eastern Shore of Virginia and Maryland and the city of Virginia Beach, VA during the Spring and Fall of 2017 and 2018. We searched for bird nests in pollinator-friendly plots during the summers of 2017 and 2018. There were no differences in alpha diversity, defined as the number of species per farm per survey period, between control and pollinator farms in either Spring or Fall. We did find differences in species evenness on farms during Spring surveys, as measured by Simpson's index, with pollinator farms having a higher mean Simpson's index. When examining factors relating to presence/absence of our 15 modeled bird species out of 110 species detected on farms, landscape-level cover types were influential in 14 species and presence of pollinator plots was influential for 5 species. After stratification of density estimates by control and pollinator farm study sites, we found that during Spring surveys, the blue jay (Cyanocitta cristata) and Carolina wren (Thryothorus ludovicianus) had lower density on pollinator farms. In the Fall, the blue grosbeak (Passerina caerulea) had higher density on pollinator farms. We found nesting in the pollinator-friendly plots by red-winged blackbirds (Agelaius phoeniceus; n=7). These nests were placed in locations within the pollinator plots with higher forb coverage than random points in the same plots without nests. We estimated the presence and relative activity of bats in 4 cover types, including forest trail, a forested pond edge, a crop field on forest edge, and a farmscaped wildflower plot, on the Eastern Shore Agricultural Research Extension Center in Painter, Virginia, from April 2017- November 2019 using acoustic detectors. Of total detections, 20.11% were identified as big brown bat (Eptesicus fuscus), 17.97% evening bat (Nycticeius humeralis), 15.35% silver-haired bat (Lasionycteris noctivagans), 7.11% eastern red bats (Lasiurus borealis), 3.66% hoary bats (Lasiurus cinereus), 3.1% little brown bat (Myotis lucifugus), and 1.38% tricolored bat (Perimyotis subflavus). Relative activity measured by calls per night varied by cover type, with relative activity highest for all 7 species in the crop field-forest edge and water-forest edge cover types as compared to pollinator plot and forest trail cover types during the maternity season (May-August). All 7 bat species were recorded in the pollinator plot cover type; of the 8,877 calls in pollinator plots, 26.07% were silver-haired bat, 25.21% eastern red bats, 23.78% evening bat, 9.32% hoary bats, 9.11% little brown bat, 5.42% big brown bat, and 1.09% tricolored bat. We used camera trap surveys to measure white-tailed deer and wild turkey occupancy across 20 farms on the Eastern Shore of Virginia and in the city of Virginia Beach, Virginia during the Spring and Fall of 2017 and 2018. Of all wild species photographed, white-tailed deer were most abundant (TS, # captures/100 nights) each survey season, however this varied season to season (Spring 2017 = 98.44 TS, Fall 2017 = 106.01 TS, Spring 2018 = 80.52 TS, Fall 2018 = 99.71 TS). Wild turkey total survey camera trap success was low compared to deer and other wildlife (4.51 TS), and also varied seasonally (Spring 2017 = 1.73 TS, Fall 2017 = 1.50 TS, Spring 2018 = 7.63 TS, Fall 2018 = 5.95 TS). White-tailed deer were detected at all survey locations at least once, and the occupancy of deer decreased as the percentage of developed land within 1km of a farm increased in each survey season. The factors relating to wild turkey occupancy varied by season. In Spring 2017, wild turkey occupancy increased as the percent of natural cover within 1 km of a farm increased. In Spring 2018, wild turkey occupancy decreased as the percent of developed land within 1 km increased. However, landscape variables did not influence wild turkey occupancy in the Fall seasons; rather in Fall 2018 we found that wild turkey occupancy decreased as camera trap success of farm machinery being used increased. Overall, wild turkey had a fairly low presence on all survey sites with an occupancy ranging from 0.18-0.53%, and no clear relationship to explain the change in survey season to season or year to year. Based on these results, pollinator plot presence or absence was not found to influence detection or occupancy of either of these target game species. Rather, other factors, mainly landscape-scale features, were found to have the largest influence on both species' occupancy and presence. Our study is one of just a few in North America to demonstrate some potential benefits of pollinator-friendly plantings to multiple different wildlife species with cultural, recreational, and insect-regulating ecosystem service benefits to landowners. Generally, birds, bats, and our focal game species' presence relied on surrounding landscape variables and forest-edge configurations more than the presence of pollinator friendly plantings. This is probably in part due to the small size of our pollinator plots. We recommend that future work explore potentially increasing the size of pollinator plot plantings or placing pollinator plantings in locations on the landscape with the most surrounding natural area, and least development, to maximize the benefits of this resource to diverse wildlife species with home ranges that are often larger than any one farm. / Master of Science / Pollinator-friendly wildflower and native grass plantings are increasingly used by state and federal agencies to improve benefits from biodiversity such as increases in crop pollinating insects, but the potential benefits of such plantings for vertebrate wildlife are not well studied. We evaluated potential ecosystem services, or even disservices, of pollinator-friendly plantings related to vertebrate wildlife, such as resident, migratory, and nesting birds (e.g., wild turkey), resident and migratory bats, and white-tailed deer. Bird point counts were conducted across 20 farms on the Eastern Shore of Virginia and Maryland and the city of Virginia Beach, VA during the Spring and Fall of 2017 and 2018, and we searched for bird nests in pollinator-friendly plots during the summers of 2017 and 2018. Over the entire project, we saw 110 different species; 96 were identified as insectivorous, indicating the potential for insect regulating services from birds. The total number of bird species observed on farms with pollinator plots were higher than farms without (100 > 90). After division of density estimates between control and pollinator farm study sites, we found that during Spring surveys, the Carolina wren had lower density on pollinator farms while in the Fall the blue grosbeak had higher density on pollinator farms. We found 7 nests of red-winged blackbirds (n=7) in the pollinator-friendly plots and birds preferred nesting in locations within the pollinator plots with more dense flowering plants without woody stem coverage than random points without nests in the same plots. We examined the presence and relative activity of bats in 4 cover types, including forest trail, a forested pond edge, a crop field on forest edge, and a farmscaped wildflower plot on one of our farm sites at the Eastern Shore Agricultural Research Extension Center in Painter, Virginia, from April 2017- November 2019 using acoustic detectors that record bat echolocation. All 7 bat species were recorded in the pollinator plot cover type and of total farm detections, 20.11% were identified as big brown bat, 17.97% evening bat, 15.35% silver-haired bat, 7.11% eastern red bats, 3.66% hoary bats, 3.1% little brown bat, and 1.38% tricolored bat. As expected, relative activity varied by cover type, with relative activity highest for all 7 species in the crop field-forest edge and water-forest edge cover types as compared to pollinator plot and forest trail cover types during the maternity season (May-August). We used camera trap surveys to measure white-tailed deer and wild turkey camera trap success and occupancy across 20 farms on the Eastern Shore of Virginia and in the city of Virginia Beach, Virginia during the Spring and Fall of 2017 and 2018. Of all wild species photographed, white-tailed deer had the highest observations. Wild turkey detections were low compared to deer and other wildlife. White-tailed deer and wild turkey presence were not influenced by the presence of pollinator plots, but rather by other factors, mainly landscape features within 1 km. Our study is one of the first in North America to demonstrate some potential benefits of pollinator-friendly plantings to multiple different wildlife with cultural, recreational, and insect-regulating ecosystem service benefits to landowners. Generally, birds, bats, and our focal game specie's presence relied on surrounding landscape variables and forest-edge configurations than the presence of pollinator friendly plantings. This is probably in part due to the small size of our pollinator plots. We recommend that future work explore potentially increasing the size of pollinator plot plantings or placing pollinator plantings in locations on the landscape with the most surrounding natural area, and least development, to maximize the benefits of this resource to diverse wildlife species with home ranges that are often larger than any one farm.
2

Challenges of regional hydrological modelling in the Elbe River basin : investigations about model fidelity on sub-catchment level

Conradt, Tobias January 2013 (has links)
Within a research project about future sustainable water management options in the Elbe River basin, quasi-natural discharge scenarios had to be provided. The semi-distributed eco-hydrological model SWIM was utilised for this task. According to scenario simulations driven by the stochastical climate model STAR, the region would get distinctly drier. However, this thesis focuses on the challenge of meeting the requirement of high model fidelity even for smaller sub-basins. Usually, the quality of the simulations is lower at inner points than at the outlet. Four research paper chapters and the discussion chapter deal with the reasons for local model deviations and the problem of optimal spatial calibration. Besides other assessments, the Markov Chain Monte Carlo method is applied to show whether evapotranspiration or precipitation should be corrected to minimise runoff deviations, principal component analysis is used in an unusual way to evaluate local precipitation alterations by land cover changes, and remotely sensed surface temperatures allow for an independent view on the evapotranspiration landscape. The overall insight is that spatially explicit hydrological modelling of such a large river basin requires a lot of local knowledge. It probably needs more time to obtain such knowledge as is usually provided for hydrological modelling studies. / Innerhalb eines Forschungsprojekts zu zukünftigen nachhaltigen Optionen der Wasserwirtschaft im Elbe-Einzugsgebiet mußten quasi-natürliche Abflußszenarien bereitgestellt werden. Zu diesem Zweck wurde das räumlich diskretisierte ökohydrologische Modell SWIM eingesetzt. Nach den von dem stochastischen Klimamodell STAR angetriebenen Szenariosimulationen würde die Region deutlich trockener werden. Allerdings ist das Hauptthema dieser Dissertation die Herausforderung, die Ansprüche an hohe Modelltreue auch für kleinere Teileinzugsgebiete zu erfüllen. Normalerweise ist die Qualität der Simulationen für innere Punkte geringer als am Gebietsauslaß. Vier Fachartikel-Kapitel und das Diskussionskapitel beschäftigen sich mit den Gründen für lokale Modellabweichungen und dem Problem optimaler räumlicher Kalibrierung. Unter anderem wird die Markovketten-Monte-Carlo-Methode angewendet, um zu zeigen, ob Verdunstung oder Niederschlag korrigiert werden sollte, um Abweichungen des Abflusses zu minimieren, die Hauptkomponentenanalyse wird auf eine unübliche Weise benutzt, um lokale Niederschlagsänderungen aufgrund von Landnutzungsänderungen zu untersuchen, und fernerkundete Oberflächentemperaturen erlauben eine unabhängige Sicht auf die Verdunstungslandschaft. Die grundlegende Erkenntnis ist, daß die räumlich explizite hydrologische Modellierung eines so großen Flußeinzugsgebiets eine Menge Vor-Ort-Wissen erfordert. Wahrscheinlich wird mehr Zeit benötigt, solches Wissen zu erwerben, als üblicherweise für hydrologische Modellstudien zur Verfügung steht.
3

Plant-insect interactions in changing environments / Pflanze-Insekt Interaktionen unter dem Einfluß von Umweltveränderungen

Gladbach, David Joachim 06 July 2010 (has links)
No description available.

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