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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.
171

Perception and Value Assessment of Ecosystem Services in Rural and Urban Regions in Ecuador

Navarrete Arias, Roberto S. 01 September 2022 (has links) (PDF)
Land use/land cover (LULC) plays a vital role in the provision of ecosystem services. Changing natural vegetation to agricultural or urban uses affectss the socio-economic dynamics of the surrounding populations. Changing land use may also result in the impairment of ecosystem services. Rural and urban communities have different realities and perceptions on the importance of ecosystem services, which tend to vary by economic, generational, social, and cultural factors. This study assesses the subjective value of people in urban and rural communities on provisioning, regulating, and cultural ecosystem services. A quantitative and qualitative survey using interviews and spatial analysis with GIS is used to study ecosystem services. The survey evaluates the values, perceptions, and benefits of ecosystems in urban and rural regions. Environmental conservation plans that have been implemented on a national level and the traditional ecological activities that local communities play a crucial role in the governance of ecosystem services. There is a need to understand the effectiveness and awareness o actions resulting from governance regimes to be both applicable and useful in protecting ecosystem services in fragile and diverse ecosystems such as Ecuador.
172

Assessing Mammal and Bird Biodiversity and Habitat Occupancy of Tiger Prey in the Hukaung Valley of Northern Myanmar

Naing, Hla 17 July 2015 (has links) (PDF)
I used results from camera traps set for tigers (Panthera tigris) during 2001-2011 in the Hukaung Valley Wildlife Sanctuary of northern Myanmar to assess overall biodiversity of large mammal and bird species, and to identify differences in photo rates inside and outside of the most protected core area of the Sanctuary. A total of 403 camera stations were deployed during October-July in the dry seasons of 2001-2011, 260 inside the Core area and 143 Outside. From 10,750 trap-nights I obtained 2,077 independent photos of wildlife species and 699 of domestic animals and humans, including 35 species of wild mammals (19 carnivores, 4 primates, 1 elephant, 6 even-toed ungulates, 1 pangolin, and 4 rodents) and 16 species of wild birds. Of these, 1 is considered critically endangered, 7 are endangered, 11 are vulnerable, and 5 are nearly threatened. Some species that probably occur in the Sanctuary (e.g., arboreal or semi-aquatic mammals) were not photographed, likely because of camera placement. In total, 48 wild species were photographed in the Core area vs. only 33 at locations Outside of the core area. Generally, few photos of any domestic animal species were obtained inside 9 the Core area, and no photos insurgents were obtained there, but many more photos of poachers and villagers, but also park rangers, were obtained there. Increased patrol efforts may have helped maintain species presence in the Core area, but differences in photo rates between areas were likely mostly influenced by differences in elevation, slope, density of streams, trails, and roads, and perhaps vegetative cover type. Tiger abundance is most influenced naturally by prey availability and anthropogenically by poaching. In the Hukaung Valley Wildlife Sanctuary in northern Myanmar, a major conservation area established to protect tigers, tiger presence has declined. This study was conducted to assess habitat occupancy and distribution of principal tiger prey species in the Core part of the Sanctuary by surveying for sign on 1650.9 km partitioned into 554 sampling units during November 2007 and May 2008. Using standard occupancy model in the program PRESENCE (6.2), habitat occupancy and detection probabilities were predicted and the best candidate model for each species was selected using the Akaike information criterion (AIC). By incorporating 7 environmental and 4 social covariates, the predicted habitat occupancy rates were 0.76 (SE=0.196, naïve estimate = 0.5162) for gaur (Bos gaurus), 0.91 (SE=0.03, naïve estimate = 0.7762) for sambar (Rusa unicolor), 0.57 (SE = 0.003, naïve estimate = 0.3195) for wild pigs (Sus scrofa) and 0.89 (SE = 0.001, naïve estimate = 0.7996) for muntjac (Muntiacus muntjak). Overall, shorter Euclidean distances to ranger stations and trails, decreased stream density, and broadleaved evergreen/semi-deciduous forest and relatively rare rain-fed cropland habitat occurrence positively influenced prey habitat occupancy; conversely, shorter Euclidean distances to villages, roads, and streams, higher elevations, and occurrence of mixed broadleaved and needle-leaved forest habitat 10 negatively influenced occupancy. In addition, Euclidean distance to ranger stations, trails, and roads positively affections species detections, whereas shorter Euclidean distance to villages and streams, high elevations, and high precipitation negatively affected detections. Results indicate that all four prey species were relatively well-distributed through the Sanctuary Core area. However, comparisons with tiger and prey indices of abundance elsewhere suggest that prey density is low and would not likely support many tigers.
173

Juvenile River Herring in Freshwater Lakes: Sampling Approaches for Evaluating Growth and Survival

Devine, Matthew T 27 October 2017 (has links) (PDF)
River herring, collectively alewives (Alosa pseudoharengus) and blueback herring (A. aestivalis), have experienced substantial population declines over the past five decades due in large part to overfishing, combined with other sources of mortality, and disrupted access to critical freshwater spawning habitats. Anadromous river herring populations are currently assessed by counting adults in rivers during upstream spawning migrations, but no field-based assessment methods exist for estimating juvenile densities in freshwater nursery habitats. Counts of 4-year-old migrating adults are variable and prevent understanding about how mortality acts on different life stages prior to returning to spawn (e.g., juveniles and immature adults in lakes, rivers, estuaries, and oceans). This in turn makes it challenging to infer a link between adult counts and juvenile recruitment and to develop effective management policy. I used a pelagic purse seine to investigate juvenile river herring densities, growth, and mortality across 16 New England lakes. First, I evaluated the effectiveness and sampling precision of a pelagic purse seine for capturing juvenile river herring in lakes, since this sampling gear has not been systematically tested. Sampling at night in June or July resulted in highest catches. Precision, as measured by the coefficient of variation, was lowest in July (0.23) compared to June (0.32), August (0.38), and September (0.61). Simulation results indicated that the effort required to produce precise density estimates is largely dependent on lake size with small lakes (<50 >ha) requiring up to 10 purse seine hauls and large lakes (>50 ha) requiring 15–20 hauls. These results suggested that juvenile recruitment densities can be effectively measured using a purse seine at night in June or July with 10–20 hauls. Using juvenile fishes captured during purse seining in June–September 2015, I calculated growth and mortality rates from sagittal otoliths. Density, growth, and mortality were highly variable among lakes, and mixed-effects regression models explained 11%–76% of the variance in these estimates. Juvenile densities ranged over an order of magnitude and were inversely related to dissolved organic carbon. Juvenile growth rates were higher in productive systems (i.e., low secchi depth, high nutrients) and were strongly density-dependent, leading to much larger fish at age in productive lakes with low densities of river herring compared to high density lakes. Water temperature explained 56%–85% of the variation in juvenile growth rates during the first 30 days of life. Mortality was positively related to total phosphorous levels and inversely related to hatch date, with earlier hatching cohorts experiencing higher mortality. These results indicate the importance of water quality and juvenile densities in nursery habitats for determining juvenile growth and survival. This study encourages future assessments of juvenile river herring in freshwater and contributes to an understanding of factors explaining juvenile recruitment that can guide more effective and comprehensive management of river herring.
174

Multi-Scale Assessment of Oceanic Sargassum habitat for the Sea Turtle 'Lost Years'

Sacco, Alexander E 01 January 2024 (has links) (PDF)
Floating marine structures, like the brown macroalgae Sargassum, provide essential habitat and support several life history stages for many marine organisms; habitat fragmentation and persistence of these floating habitats are poorly understood. Extending landscape ecology principles to the seascape realm requires new methodologies to understand dynamics of patch mosaics and functional utility of the moving seascape system. I examine Sargassum in a seascape ecology context, exploring 1) structural descriptions of the Sargassum patch seascape and whether 2) historical Sargassum patch distribution is represented by delineated proposed and finalized Sargassum-as-a-critical-habitat designations under the US Endangered Species Act (ESA). I utilize historical Sargassum data at two spatial scales: a coarse scale (1.6km) and a medium scale (328m) to determine whether habitat fragmentation processes are occurring at either spatial scale across seven marine regions in the Northern Atlantic Ocean. In the Gulf of Mexico specifically, the size of Sargassum patches is increasing, while the Caribbean Sea Sargassum patch density has increased by an order of magnitude during the study period suggesting habitat gain. In the Northern Brazil Shelf and the Sargasso Sea, there is evidence of habitat fragmentation occurring due to rapid changes in patch density, proportion of seascape, and distance between patches. In addition, all regions within the study area exhibit cyclic patterns, which suggests Sargassum habitat characteristics may occur alternating between high and low years, which can impact critical habitat strategies for Sargassum. Lastly, Sargassum patches were found to exhibit a notable increase in occurrence within the ESA's proposed green turtle critical habitat designation of Sargassum when compared with the ESA's loggerhead critical habitat Sargassum designation Sargassum. These data provide valuable insight into Sargassum as an important and highly dynamic seascape that may provide critical habitat for dispersal-stage juvenile sea turtles during their oceanic ‘lost years.'
175

Management of Grassy Balds Communities in the Roan Highlands

Donaldson, James T., Schubert, Nora, Huff, L. C. 01 May 2009 (has links) (PDF)
The Highlands of Roan Mountain best exemplify that which is rare and unique within high elevation communities of the Southern Appalachian Mountains. The Roan Highlands are protected through a landscape-level conservation initiative originally established by the Southern Appalachian Highlands Conservancy (SAHC) and the U. S. Forest Service (USFS) in 1974. The Roan massif rises more than 6,000 feet above mean sea level and straddles the border of North Carolina and Tennessee in the Pisgah and Cherokee National Forests, respectively. Among its unique aspects, the Roan supports at least 800 known plant species, 27 rare plant communities, and 33 federally or state-listed threatened and endangered species; as of this writing, 35 species obtain a rank of G3, G2, or G1. The Roan’s threatened community types include: Heath Balds, Seeps, Red Spruce-Fraser Fir Forests, Grassy Balds, and Rocky Summits, of which the latter three are deemed in need of restoration, in addition to preservation. The Grassy Balds have been a focus of management in the Roan Highlands, largely due to their iconic status within these high elevation communities. To wit, the Grassy Balds provide splendid, panoramic views of the high elevation landscape; they predate European settlement and their origins are enigmatic; the Roan’s Grassy Balds represent the highest quality and the longest linear stretch of this community type remaining in the Southern Appalachians; they provide habitat for numerous regionally and locally rare species. The Roan’s Grassy Balds currently occupy less than 25 percent of their historic extent. Trees, shrubs, and blackberries have encroached into the Grassy Balds due to a lack of natural and anthropogenic disturbances and inadequate levels of management. With so much biodiversity at stake, the scientific and conservation communities determined that broad management partnerships are necessary to sustain the rare elements of the Roan; multiple governmental and non-governmental organizations have worked together toward mutual conservation goals since the early 1970s. Currently known as the Roan Stewardship Committee, these managing entities collaborated with the U.S. Forest Service to establish a restoration goal of nearly 1,000 acres of the Roan’s Grassy Balds in 1991, but that goal has not been met. In this study, we will present information recently gathered by members of the Roan Stewardship Committee on efforts to maintain and restore Grassy Balds communities in the Roan Highlands, emphasizing recent summaries of historic and current adaptive management efforts, as well as data from the first year (2008) of a browsing study known as the Baa-tany Goat Project.
176

Effects of Mountaintop Removal Mining on Population Dynamics of Stream Salamanders

Freytag, Sara B. 01 January 2016 (has links)
Mountaintop removal mining (MTR) is a notorious stressor of stream ecosystems in the Central Appalachians. Valley fills (VF) lead to reduced occupancy, abundance, and species richness of stream salamanders. Multiple factors may be responsible for these reductions, but specifically habitat fragmentation and degradation may reduce colonization rates and increase local extinction rates. From 2013-2015, repeated counts of salamanders were conducted in stream reaches impacted by MTR/VF and compared to counts in reference reaches to answer the question: do stream salamander population dynamics differ between stream reaches impacted by MTR/VF and reference stream reaches? I also investigated dynamics of stream habitat using measures relevant to stream salamander persistence. Accordingly, I examined number of cover objects, percent detritus, hydroperiod, and specific conductance. From the salamander capture data, colonization and survival probabilities were lower in MTR/VF reaches than reference reaches. MTR/VF reaches also had fewer cover objects, higher percent detritus, constant stream flow, and elevated specific conductance. Although specific conductance was increased in MTR/VF reaches, it was not strongly correlated with colonization and survival. I suggest reduced rates of colonization and survival in MTR/VF stream reaches are driven by inhibited dispersal and reduced individual survival due to degraded terrestrial and aquatic environments.
177

Evaluating the Influences of Karst Hydrogeology on Freshwater Harmful Algal Blooms in Kentucky Lakes

Schaefer, Robert T 01 July 2016 (has links)
A problem exists in Nolin River Lake and Rough River Lake in Kentucky, due to the increasing prevalence of cyanobacterial-based harmful algal blooms (CyanoHABs) and the threats they pose to local communities. These lakes were developed as artificial reservoirs from embankment. Further complicating the issue, the lakes are located within a heavily karstified region and there exists no plan or method currently for monitoring or managing CyanoHABs in a karst region with regard to groundwater inputs to the lake systems or their tributaries. A mixture of techniques and analysis methods was used to determine the best way to monitor and possibly detect the formation and occurrence of CyanoHABs in artificial lakes that are located in karst landscapes. The methods focused on determining the effect groundwater has on CyanoHAB occurrence and formation, how much nutrient pollution is entering the system, from where the pollution is originating and, ultimately, how best to monitor and develop management practices against CyanoHAB occurrence. Techniques used included dual nitrate isotope tracing, collecting hydrogeochemical data, lake discharge data, historical CyanoHAB data, and biological tracer monitoring in both lakes. The lakes under study showed varying degrees of the influence karst plays in their seasonal changes from summer to winter pools. Lake water temperatures never dropped below the temperatures needed for one of the dominant cyanobacteria, Cylindrospermopsis raciborskii, to grow. Calculations of nutrient loadings indicated that over 3.5 x 106 kg of nitrate moved through Nolin River Lake during the course of the study. The presence and concentrations of E. coli when paired with weather and geochemical data also revealed karst groundwater pulses exerting an influence through the system in response to precipitation events. The nitrogen and oxygen isotope data indicate that a wide variety of nitrate pollution sources are entering the system and that a variety of management techniques must be deployed to combat this complex issue. A holistic approach that focuses on management and education about karst processes and CyanoHABs is suggested, with an emphasis on broader community involvement beyond just the populations living adjacent to the lakes.
178

Mechanisms Responsible for Sinkhole Flooding on an Urbanized Karst Terrain: South Sunrise / Media Drive, Bowling Green, Kentucky

Feeney, Thomas 01 December 1986 (has links)
Sinkhole flooding on the urban karst area of Bowling Green, Kentucky, was studied by investigating past flood events in the South Sunrise/Media Drive Sinkhole. The actual flood levels of four floods were compared to levels calculated by an empirical runoff determination method. Outflow capacity tests and dye tracing revealed the nature of drainage within the karst depression. The Soil Conservation Service runoff determination method and the three-hour maximum rainfall event were used to estimate the level of flooding. Three of the four flood events studied provided deviations between the actual and calculated flood levels of less than 0.26 feet (0.08 meters). The fourth event produced a deviation of 1.45 feet (0.44 meters) which was explained by the intense nature of the precipitation event. Analysis of the data resulted in the conclusion that surface storm water runoff exceeded the outflow capacity of the sinkhole drains during all four flood events and that the peak flood elevations were not related to the level of the water table in the area. Evidence also suggested that drainage from the base of the South Sunrise/Media Drive Sinkhole occurs through interconnecting voids associated with a cave roof breakdown pile, and not through an efficient system of solution conduits.
179

Decision Support for Natural Resource Management

Cummings, Jonathan 01 January 2014 (has links)
This research spans a variety of research topics with a common theme, providing decision support through the development and analysis of methods that assist decision making for natural resource and wildlife management. I used components of structured decision making and decision analysis to address natural resources management problems, specifically monitoring and estimating the status of harvested populations, as well as data collection decisions for landscape conservation. My results have implications for the way populations are monitored and their status is estimated. I find that the inclusion of error in data collection can have a substantial impact of the performance of abundance and growth rate estimates of harvested species and that the selection of estimation methods depends on what management objectives are most important. For example, the Sex-Age-Kill population estimation method best estimates the size of populations, while the Downing population reconstruction method better estimates trends in population growth rates. I provide a framework to support selection of the best estimation method while considering a monitoring program as a whole. Based on this framework the Vermont Fish and Wildlife Department will obtain the most benefits from a monitoring program including necropsy analysis that uses the Downing method to track population status. Finally, I demonstrated the use of value of information analysis as a tool to determine the relative expected benefits of addition spatial data collection for use in landscape mapping and conservation. This type of analysis can provide conservation agencies with a planning tool to direct budgets and mapping efforts.
180

Using stable isotope analysis to estimate black bear (Ursus americanus) diet in Vermont

Dykstra, Eliese Antona 01 January 2015 (has links)
The black bear (Ursus americanus) is an iconic species with cultural, economic and ecological importance in Vermont, USA. Bears exhibit a highly variable diet, and few studies have described bear diet in the state. Information on diet may provide insight into foraging behavior, thus allowing managers to better assess patterns of human-bear conflict. My objectives were to estimate the relative contribution of food items to bear diet and how factors including sex, habitat, food availability, and nuisance status describe patterns of consumption. I collected samples from bears and major food groups including C3 plants, white-tailed deer (Odocoileus virginianus), corn (Zea mays), and human foods, then quantified diet using stable isotope analysis. Samples were collected from 71 bears, 547 plants, and 38 deer throughout Vermont. I also collected 12 corn samples, and 20 human hair samples to represent anthropogenic foods. I determined δ13C and δ15N isotope values for all samples, then used Bayesian mixing models to estimate the contribution of foods and effect of each factor on proportional contribution estimates. Nuisance status best described patterns of diet over other factors. Median percent contributions for non-nuisance bears were 73.2% C3 plants, 23.8% corn, 1.9% human foods, and 0.5% deer. Median percent contributions for nuisance bears were 64.6% C3 plants, 28.9% corn, 3.2% human foods, and 0.7% deer. Factors such as sex, habitat, and food availability exerted less effect on diet than expected. Proportional contribution of meat was lower than in some other parts of North America, suggesting bears forage differently in Vermont. Results provide the first statewide estimate of bear diet and indicate corn may represent a much larger component of diet than previously thought. In particular, bears labeled as nuisance animals may forage on greater proportions of corn throughout the year.

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