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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

Comparison of Bird Communities between Secondary Natural Forests and Cryptomeria (Cryptomeria japonica) Plantations

Chang, Ying-Cheng 14 February 2008 (has links)
The purpose of this study is to compare the bird communities between mature secondary forests and Cryptomeria (Cryptomeria japonica) plantations. Bird census was carried out in Teng-jhih National Forest Recreation Area, Kaohsiung county, Taiwan during both breeding season and non-breeding season from March to November in 2007. To compare bird communities between two types of forests, diversity index, evenness index, species richness and densities of bird were calculated. Densities of birds were estimated by variable circular-plot point count method. All birds were classified into 10 assemblage guilds. ANOVA was used to examine whether forest types, breeding season and monthly changes will effect the composition of bird communities. A total of 36 bird species of 19 families were recorded during the study period. All of these species were found in secondary forests, and only 27 of them were observed in Cryptomeria plantations. The results showed that bird diversity, abundance and total densities were higher in secondary forests than those in Cryptomeria plantations, either during breeding season or non-breeding season. Canopy tree species of families, Lauraceae and Fagaceae of the secondary forests which can provide more foods than Cryptomeria, canopy foliage omnivores and woodpeckers were more in secondary forests than in Cryptomeria plantations. On the other hand, the openess of shrubs and understory vegetation in the Cryptomeria plantations, shrub foliage omnivores were more in Cryptomeria plantations than in secondary forests.
2

Comparing the Use of Abundance and Consistent Occupancy Measures to Predict Local Species Persistence

Grouios, Christopher 03 January 2011 (has links)
I compared the utility of two continuous time-series data measures for applied conservation biology by investigating how well each could predict future local persistence of a diverse set of bird species. I used 37 years of data from the North American Breeding Bird Survey to calculate abundance from yearly point-counts and permanence (i.e., consistent occupancy over time) from yearly presence-absence data in the early portion of the study period, then used the later portion of data to empirically evaluate how well each measure predicted persistence two decades into the future. I found that permanence could only match the ability of abundance to accurately predict local species persistence if multiple within-year repeated observations contributed to its calculation. Neither measure was effective at predicting persistence for regionally rarer species. I suggest the yearly and within-year repeated collection of abundance estimating data for use in applied conservation biology to best ensure biodiversity persistence.
3

Comparing the Use of Abundance and Consistent Occupancy Measures to Predict Local Species Persistence

Grouios, Christopher 03 January 2011 (has links)
I compared the utility of two continuous time-series data measures for applied conservation biology by investigating how well each could predict future local persistence of a diverse set of bird species. I used 37 years of data from the North American Breeding Bird Survey to calculate abundance from yearly point-counts and permanence (i.e., consistent occupancy over time) from yearly presence-absence data in the early portion of the study period, then used the later portion of data to empirically evaluate how well each measure predicted persistence two decades into the future. I found that permanence could only match the ability of abundance to accurately predict local species persistence if multiple within-year repeated observations contributed to its calculation. Neither measure was effective at predicting persistence for regionally rarer species. I suggest the yearly and within-year repeated collection of abundance estimating data for use in applied conservation biology to best ensure biodiversity persistence.
4

Comparing avifauna communities and bird functional diversity of forest and farmland in southwest Ethiopia

Engelen, Dries January 2012 (has links)
Worldwide degradation and conversion of tropical forests affects many species and their provided ecosystem services. Among them are birds, responsible for pollination, seed dispersal, pest control and scavenging. This study, conducted in southwest Ethiopia, compares species composition and bird functional diversity between forest and homegardens close to and far from forest, both in terms of species numbers and bird abundances. Point counts and mist netting were used to obtain data. While the former method detected more species, abundance data from the latter revealed patterns not observed by just comparing species numbers. I found that species diversity was lower in forest compared to gardens and that the species composition of both communities was significantly distinct. Whereas forest had more forest specialists, gardens held more forest visitors and species of open country. Close and far gardens did not differ in any aspect, except that abundances of forest generalist birds were somewhat higher close to forest. Regarding bird feeding guilds, I found that granivores and nectarivores were more numerous in gardens, while frugivores were more common in forest. Carnivores and omnivores showed no effect. Insectivore proportions were the same for forest and farmland, but their numbers (including those of all sub-guilds) were higher in gardens. The Ethiopian forest avifauna is poor in comparison with other Afromontane regions, lacking several, mostly insectivorous genera. This could be the result of an extinction after which its geographic isolation made recolonization difficult, especially for dispersal-limited understory species. Nonetheless, and despite their impoverished state, the results suggest that forest remnants are important for forest-dependent species, being a stronghold for forest specialists and supporting higher numbers of forest generalists in nearby gardens. However, future forest regrowth might be at stake with ongoing agricultural encroachment, because gardens hold fewer frugivores, especially forest specialists, which might affect seed dispersal. / Många arter påverkas negativt av avskogning och annan mänsklig påverkan på tropiska skogar, vilket också kan få konsekvenser för de ekosystemtjänster dessa arter levererar. En viktig artgrupp i detta avseende är fåglar, som kan ha betydelse för pollination, fröspridning, naturlig skadedjurskontroll och som asätare. Denna studie, utförd i sydvästra Etiopien, jämför artsammansättning och funktionell diversitet hos fåglar i skogar och trädgårdar både nära och långt ifrån skogen. Både antal arter och antal individer har undersökts. Data materialet bygger både på observationer från punktinventering och fåglar fångade med slöjnät. Med den första metoden noterade jag fler arter, medan abundansvärden från den andra metoden gjorde att jag såg mönster som inte syntes vid endast jämförelser av artrikedom. Jag fann att artrikedomen var lägre i skogen i jämförelse med trädgårdarna, men att artsammansättningen var signifikant skiljd däremellan. Skogarna hade fler skogsspecialister medan trädgårdarna hade fler arter från öppna marker och tillfälliga skogsbesökande arter. Trädgårdar som låg nära eller långt ifrån skogen skiljde sig inte på något sätt utom att individtätheten av skogsgeneralister var något högre i trädgårdar nära skogen. När det gäller uppdelningen av fåglarna utifrån vad de äter så fann jag att fröätande och nektarätande arter var vanligare i trädgårdar medan fruktätande arter var vanligare i skogen. Rovfåglar och allätare uppvisade inget tydligt mönster. Proportionen insektsätande fåglelarter var samma i skogen och trädgårdarna, men det absoluta antalet arter (inklusive alla olika underkategorier) var högre i trädgårdarna. Den etiopiska skogsfågelfaunan är artfattig i förhållande till andra bergstrakter i Afrika och saknar flera släkten av framförallt insektsätande fåglar. Detta skulle kunna bero på ett tidigare utdöende varefter en senare återkolonisering varit svår på grund av den geografiska isoleringen, speciellt för insektsätande fåglar som huvudsakligen finns i undervegetationen. Trots den relativa artfattigdomen så visar resultatet från min studie hursomhelst på att skogarna är viktiga för skogsberoende fåglar. Den största betydelsen har de för skogsspecialister där, men även genom en positiv effekt på abundansen av skogsgeneralister i närliggande trädgårdar. Dock kan framtida återväxt av skogar bli problematisk på grund av en pågående omvandling av skogar till trädgårdar, eftersom trädgårdar hyser färre fruktätande fåglar, vilket kan påverka fröspridning över landskapet. / Examining mismatches between management and the supply of ecosystem services in Ethiopian agroecosystems across scales in space and time
5

Cohomology of the moduli space of curves of genus three with level two structure

Bergvall, Olof January 2014 (has links)
In this thesis we investigate the moduli space M3[2] of curves of genus 3 equipped with a symplectic level 2 structure. In particular, we are interested in the cohomology of this space. We obtain cohomological information by decomposing M3[2] into a disjoint union of two natural subspaces, Q[2] and H3[2], and then making S7- resp. S8-equivariantpoint counts of each of these spaces separately. / Målet med denna uppsats är att undersöka modulirummet M3[2] av kurvor av genus 3 med symplektisk nivå 2 struktur. Mer specifikt vill vi hitta informationom kohomologin av detta rum. För att uppnå detta delar vi först upp M[2] i en disjunkt union av två naturliga delrum, Q[2] och H3[2], och räknar därefter punkterna av dessa rum S7- respektive S8-ekvivariant.
6

Cohomology of the moduli space of curves of genus three with level two structure

Bergvall, Olof January 2014 (has links)
In this thesis we investigate the moduli space M3[2] of curves of genus 3 equipped with a symplectic level 2 structure. In particular, we are interested in the cohomology of this space. We obtain cohomological information by decomposing M3[2] into a disjoint union of two natural subspaces, Q[2] and H3[2], and then making S7- resp. S8-equivariantpoint counts of each of these spaces separately. / Målet med denna uppsats är att undersöka modulirummet M3[2] av kurvor av genus 3 med symplektisk nivå 2 struktur. Mer specifikt vill vi hitta informationom kohomologin av detta rum. För att uppnå detta delar vi först upp M[2] i en disjunkt union av två naturliga delrum, Q[2] och H3[2], och räknar därefter punkterna av dessa rum S7- respektive S8-ekvivariant.
7

Avian Community Patterns In The Lesser Caucasus (northeastern Turkey)

Atkin Gencoglu, Gulden 01 December 2007 (has links) (PDF)
ABSTRACT AVIAN COMMUNITY PATTERNS IN THE LESSER CAUCASUS (NORTHEASTERN TURKEY) ATKIN GEN&Ccedil / OgLU, G&uuml / lden M. Sc., Department of Biological Sciences Supervisor: Assoc. Prof. Dr. C. Can Bilgin December 2007, 78 pages Species composition, diversity and species-habitat relations are widely used to describe communities. This study aimed to document diversity, composition and habitat relations of avian communities of the Turkish Lesser Caucasus by using point counts and multivariate analyses. 2845 individuals of 101 bird species were observed at 215 stations located in the study area. Point counts were revealed to be a useful method for terrestrial birds, especially passerines. Species richness and diversity changed significantly within parts of the study area and one particular sub-region was found to be considerably more diverse than the other three. Division of the Lesser Caucasus region into sub-ecoregions may not be justified using bird assemblages since habitat parameters, especially the presence of woody vegetation, seemed to be a better predictor of species composition than geographical proximity. Documented bird and habitat associations provide valuable information on the factors which affect bird occurrence or abundance. Baseline data provided by this study will help detect and understand changes in bird populations in the future. Keywords: avian community, species composition, species diversity, point count method, bird-habitat relationship
8

Perinčių paukščių bendrijų rūšinė sudėtis ir vietos populiacijų gausumo dinamika Lietuvoje / Species composition of the breeding bird community and dinamics of numbers of local populations in Lithuania

Stonytė, Danguolė 08 June 2005 (has links)
As the breeding bird communities and population numbers have not been widely studied in Lithuania, there is not much local literature on the subject. Traditionaly for decades more attention was given to the migrating birds in Lithuania. From 1995 the Lithuanian Ornithological Society have been systematically making bird breeding population survey when usung point count methodology. This was the first attempt to computer and analyze the data of the point count studies made by the Lithuanian Ornithological Society in 1996-2004. During the point count survey 158 species of birds were recorded. Among them the Passeriformes species predominate. Our observations shows that Fringilla coelebs, Erithacus rubecula predominantes in the forested landscapes. Alauda arvensis and Sturnus vulgaris are predominating in bird communities assciations in the agricultural landscape. Numbers of local breeding populations were fluctuating mostly among years but were near stable during the period. Local populations of Anthus trivialis and Carduelis chloris have increased in minimum 20%. At the some time local breeding populations of Carduelis carduelis and Sturnus vulgaris have decreased in minimum 20%.
9

Effects of EMF Emissions from Undersea Electric Cables on Coral Reef Fishes

Jermain, Robert F 18 July 2016 (has links)
The objective of this project was to determine if the electromagnetic field (EMF) emissions from undersea power cables impacted the local and transient marine life, with an emphasis on reef fishes. The work was done at South Florida Ocean Measurement Facility of Naval Surface Warfare Center, Carderock Division, Broward County, Florida. This facility functions as the hub for a range of active undersea detection and data transmission cables. It has multiple active submarine power cables that extend several miles offshore and which can deliver power and enable data transmission to and from a range of acoustic and EMF sensors. The cables lie directly on the seabed, are buried in the sand, or are suspended in the water column. EMF emissions from a selected cable were created during SCUBA fish surveys. During the surveys the transmission of either alternating current (AC) or Direct Current (DC) was randomly intiated by the facility with no transmitted current (OFF) provided a control. The surveys were conducted using standardized transect and stationary point count methods to acquire reef fish abundances prior to and immediately after a change in transmission frequency (the divers were aware of the time of frequency change but not the specific frequencies). The divers were also tasked to note the reaction of the reef fishes to the immediate change in the EMFs emitting from the cable during a power switch. The surveys were conducted on a quarterly basis at three sampling sites offshore on the same cable. These sites were in water depths of approximately 5, 10, and 15 m, respectively and were selected based on their robust reef fish community and are representative of each of the three primary hardbottom coral reef habitats in the local offshore environment: the Inner (Shallow), Middle, and Outer (Deep) reef tracts. A total of 263 surveys were conducted: 132 transect-counts and 131 point-counts over 15 months. There were 24,473 fishes counted during transect-count surveys and with point-counts, 36,115 fishes were counted. With count types and sites combine a total of 151 species representing 35 families were recorded. An analysis of the data primarily did not find statistical differences among power states and any variables. However, this may be a Type II error as there are strong indications of a potential difference of a higher abundance of reef fishes at the sites when the power was off. There are a number of caveats to consider with this finding: the data set needs to be larger in terms of numbers of: counts, sites and eletro-sensitive species to allow for rigorous statistical analysis; also a longer time between frequency changes to allow for slower, but nonetheless important, reactions to differing EMFs might lead to differing conclusions. Obviously, more research is required to confirm the results of this study.
10

Avian Community Response to Riverby Ranch Restoration Reconstruction

Boucher, Tessa Katrish 12 1900 (has links)
Anthropogenic activities have caused many wildlife spices to decline in populations worldwide. The grassland bird communities are especially being impacted by these land use changes. Breeding success is closely tied to functional habitats for most grassland bird species in North Texas. Restoring these degraded habitats is an important component to aid in conserving wildlife biodiversity. We surveyed the bird population at Riverby Ranch Mitigation site by conducting point count sampling. This site consists of recently restored grassland, wetland, and forested habitat. This research was focused on conducting post restoration monitoring of the bird community in the early succession of the restored habitats. We set out to use the bird community as biomonitors to help assess if the restoration practices could be considered successful. We found that density estimates were more than double at the restored site when comparing to three different references sites under different management practices. This included an unrestored working ranch, a wildlife management area, and a conservation managed prairie site. We found that biodiversity metrics were as high or higher than the reference sites. In addition, we also found that there were more observations of species of high conservation concern present at the restored stie. This research supports that the reconstructive restoration that took place at Riverby Ranch was highly effective at restoring a diverse and abundant grassland and wetland bird community.

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