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Morrison, Jane H. "Flowering native weeds for the conservation of wild pollinators in agroecosystems." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/620636.
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Concerns about a global decline in pollinators have called for more knowledge about the drivers of wild pollinator abundance and diversity in agroecosystems. Agricultural intensification has been identified as the main cause of this “global pollinator crisis”, particularly, due to reductions in natural areas holding critical floral and nesting resources. Maintaining flowering weeds in agricultural field margins is often recommended as a cost-effective and efficient method of offering natural or semi-natural habitats for wild pollinator conservation.
In this study, the role of flowering weeds in supporting wild bees and other flower visiting insects in Mediterranean cereal agroecosystems was investigated. This research involved a three-year, multi-farm study (Part A) which compared field margin characteristics, including the functional constitution of their floral communities, with wild bee community composition and functional structure, from sites with landscapes of varying agricultural intensity in Catalonia, Spain. The aim of this work was to investigate the value of field margins in differing landscapes and determine which biotic and abiotic margin characteristics, and which functional attributes of margin plant communities, were important for sustaining wild bee abundance and diversity. This work also involved a two-year field trial (Part B) to compare five native flowering weed species common in Catalan cereal agroecosystems: C. arvensis, D. carota, M. sylvestris, P. rhoeas and S oleraceus. The goal was to compare the attractiveness of these species to different flower visiting insect groups, assess their value in supporting wild pollinators and analyze relationships between particular floral characteristics and insect visitation rates.
Overall, more than 4000 bees were collected and identified to genus and a database was compiled listing the morphophysiological features and behaviours of the observed genera. A large database was also compiled of all the flowering plant species observed in Part A, documenting the trait values relevant for this work. In Part A, generalized linear models indicated a strong inverse relationship between surrounding landscape diversity and wild bee abundance. The proportion of Halictidae bees (common generalists) increased with decreasing landscape complexity. Floral richness exhibited a positive association with number of foraging bees and morphospecies richness, and was positively correlated with the proportion of shrubs and trees represented in the margins. It was observed that wider margins held a higher proportion of perennial plants and a lower proportion of Halictidae bees. The functional attributes of margin plant communities that were observed to promote wild bee community robustness included: high nectar availability, diversity in flower colour, diversity in flower morphology and diversity in vegetation height. In Part B, the most visited species were P. rhoeas and D. carota (more visits to P. rhoeas in 2015 and more visits to D. carota in 2016), followed by mixed plots, M. sylvestris, C. arvensis and S. oleraceus. The influence of the specific floral traits of the studied species on visitation rates, calculated using general linear models, varied depending on the insect group. This study suggests that field margins are more crucial in intensively farmed areas than in heterogeneous landscapes where foraging resources are more abundant. Maintaining wide margins with high flowering plant richness, comprising perennial and shrub species, best supports a dense and diverse bee community. If necessary, it is recommended that margins be sown with native perennial flowers, with differing and overlapping flowering periods, high in nectar and pollen, with a diverse assortment of colours, shapes and plant heights, and that they be managed so that a diversity of nesting features are offered.La creciente preocupación sobre la disminución global de polinizadores exige un mayor conocimiento de los factores que influyen sobre la abundancia y diversidad de polinizadores en los agroecosistemas. La intensificación agrícola ha sido identificada como la causa principal de esta "crisis global de polinizadores", particularmente, debido a la reducción de las áreas naturales con recursos florales y de nidificación. El mantenimiento de "malas" hierbas con flores en los márgenes de los campos agrícolas se ha recomendado como un método rentable y eficiente de ofrecer hábitats naturales para la conservación de polinizadores silvestres. En este trabajo se ha estudiado el papel que pueden tener las "malas" hierbas con flores en el apoyo de las abejas silvestres y otros polinizadores en agroecosistemas de cereales mediterráneos. Por un lado, se ha realizado un estudio de tres años (Parte A) consistente en comparar las características de márgenes de campos de cereales en Cataluña, incluida la caracterización funcional de la comunidad floral, con la composición y estructura funcional de la comunidad de abejas. El objetivo de este trabajo fue determinar las características y atributos funcionales del margen qué respaldan mejor el mantenimiento de la comunidad de abejas silvestres en diferentes paisajes. Por otro lado, también se realizó una prueba de campo de dos años (Parte B) para comparar cinco especies nativas consideradas malas hierbas, con flores, comunes en los agroecosistemas de cereales de Cataluña: Convolvulus arvensis, Daucus carota, Malva sylvestris, Papaver rhoeas y Sonchus oleraceus. El objetivo fue comparar el atractivo de estas especies para diferentes grupos de insectos, evaluando sus valores para mantener a los polinizadores silvestres, y analizando las relaciones entre sus características florales y las visitas de estos insectos. En total se recolectaron más de 4.000 abejas y se identificaron a nivel de género. En la Parte A, los modelos lineales generalizados indicaron una fuerte relación inversa entre la diversidad del paisaje circundante y la abundancia de abejas silvestres. La proporción de abejas Halictidae aumentó con la disminución de la complejidad del paisaje. La riqueza floral mostró una asociación positiva con el número de abejas de forrajeo y la riqueza de morfoespecies. Se observó que los márgenes más amplios contenían una proporción mayor de plantas perennes y una proporción menor de abejas Halictidae. Los atributos funcionales de las comunidades de plantas de los márgenes que promovieron la robustez de la comunidad de abejas silvestres fueron la alta disponibilidad de néctar, diversidad en el color de las flores, diversidad en la morfología de las flores y diversidad en la altura de la vegetación. En la Parte B, las especies más visitadas fueron P. rhoeas y D. carota, seguido de parcelas mixtas, M. sylvestris, C. arvensis y S. oleraceus. La influencia de los rasgos florales de las especies estudiadas en las tasas de visita, calculado usando modelos lineales generales, variaba dependiendo del grupo de insectos. Este estudio sugiere que los márgenes de campo son más cruciales en áreas de cultivo intensivo que en paisajes heterogéneos. El mantenimiento de amplios márgenes con alta riqueza de plantas con flores, con especies perennes y arbustivas, es la mejor manera de apoyar una comunidad de abejas densa y diversa. Si es necesario, se recomienda que los márgenes se siembren con flores perennes nativas, con períodos de floración diferentes y superpuestos, que posean alto contenido en néctar y polen, con una diversidad de colores, formas y alturas de plantas, y que se distribuyan de modo que se facilite la anidación de insectos. En función de su atractivo general para los insectos, además de otros atributos positivos, la presencia de P. rhoeas, D. carota y M. sylvestris puede contribuir a la sostenibilidad de los agroecosistemas.
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Currey, Robin. "Diversity of Hymenoptera, Cultivated Plants and Management Practices in Home Garden Agroecosystems, Kyrgyz Republic." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/124.
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Pollination-dependent fruit trees grown in home gardens play an important role in the agricultural based economy of Central Asian countries, yet little is known about the status of pollinator communities, the cultivated plant composition or the factors that influence management practices in Kyrgyz home garden agroecosystems. As agricultural systems are human created and managed, a logical approach to their study blends anthropological and ecological methods, an ethnoecological approach. Over three years, I investigated how species richness and abundance of Hymenoptera, cultivated plants, and home garden management were related using quantitative and qualitative methods in the Issyk-kul Man and Biosphere reserve. Structured surveys were undertaken with heads of households using a random sample stratified by village. Gardens were then mapped with participation of household members to inventory edible species in gardens, most of which are pollinator-dependent, and to compare home garden diversity as reported by respondents during interviews. Apple diversity was studied to the variety level to understand respondents’ classification system in the context of in situ agrobiodiversity conservation. Household members identified 52 edible plant species when mapping the garden, compared with 32 reported when interviewed. The proportion of plant species received from others through exchange and the number of plots cultivated significantly explained the variation in edible plant diversity among gardens. Insects were sampled in gardens and orchards to determine potential pollinator community composition and the effect of different management practices on Hymenoptera richness and abundance. I collected 756 Hymenoptera individuals (56 bee; 12 wasp species); 12 species were new records for Kyrgyzstan or within Kyrgyzstan. Economic pressures to intensify cultivation could impact management practices that currently promote diversity. A home garden development initiative was undertaken to study management practice improvement. Participants in the initiative had higher adoption rates than controls of management practices that improve long-term yield, ecological sustainability and stability of home gardens. Home gardens, as currently managed, support abundant and diverse pollinator communities and have high cultivated plant diversity with few differences in community composition between garden management types.
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Bryan, Casey J. "THE EFFICACY OF COVER CROPS FOR POLLINATOR HABITAT PROVISION AND WEED SUPPRESSION IN A SOUTHERN ILLINOIS AGROECOSYSTEM." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2489.
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Increases in agricultural intensification over the past century have resulted in significant alterations to the rural landscape across the Midwest. Pollinators are essential to sustain natural and managed ecosystems. They are vital for food production and their declines have been linked, in part, to a rise in intensive agricultural practices. There is a recognized need among numerous stakeholders to build sustainability into the management of agroecosystems to protect both the biotic and abiotic resources of these systems. The use of cover crops is gaining interest among agricultural producers for benefits such as improving water quality and soil health. Cover cropping systems have the potential to provide floral resources to pollinators and suppress problematic driver weeds. The overall objective of this study was to quantify the effects of cover crops on plant and pollinator biodiversity within agricultural systems. This study aimed to characterize the pollinator diversity indicative of the patchwork mosaic forest-agroecosystem of Crab Orchard National Wildlife Refuge; evaluate the roles cover crop treatments play in supporting pollinator diversity and weed suppression benefits in a conventionally managed system; and provide the basis of recommendations for sustainable weed suppression tactics and for enhancing the quality of pollinator habitat within agricultural systems.
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Sonja, Mudri Stojnić. "Distribucija i dinamika populacija najznačajnijih grupa polinatora u agroekosistemima Vojvodine." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=107290&source=NDLTD&language=en.
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U radu je prikazana distribucija, dinamika i diverzitet insekata oprašivača iz reda Hymenoptera - Apiformes (Anthophila) i Diptera Syrphidae) na stepskim fragmentima i na suncokretu u agroekosistema Vojvodine. U cilju uvida u strukturu predela injenog uticaja na sastav i brojnost polinatora, kartirani su tipovistaništa oko svakog stepskog fragmenta. Na osnovu podataka dobijenih kartiranjem, odabrano je sedam stepskih fragmenata kojiu svom okruženju imaju visok udeo suncokreta kao masovnocvetajuće kulture i sedam stepskih fragmenata koji su bez ili saniskim udelom suncokreta. Iz reda Hymenoptera – Apoideazabeleženo je šest familija: Andrenidae, Apidae, Colletidae,Halictidae, Melittidae i Megachilidae, 114 vrsta, a iz reda Diptera(Syrphidae), registrovano je ukupno 11 vrsta. Predstavnici familija Andrenidae, Apidae i Halictidae su distribuirani na svim lokalitetima,predstavnici familije Megachilidae su distribuirani na 15 od 16lokaliteta, a najmanje su zastupljene jedinke familija Colletidae iMelittidae, distribuirane na pet lokaliteta. Polinatori reda Diptera familije Syrphidae su distribuirani na svim lokalitetima. Rezultati Kruskal-Volisovog H testa ukuzuju da je tokom sve tri sezone (2011.,2012., 2013.) na stepskim fragmentima najviše bilo zastupljeno vrsta solitarnih pčela, zatim vrsta osolikih muva, a najmanje vrsta bumbara. Istim testom je dobijano da je tokom sve tri sezone na stepskim fragmentima, registrovano najviše jedinki osolikih muva,zatim medonosne pčele, solitarne pčele, a najmanje jedinki bumbara. Fridmanovim testom su utvrđene razlike u brojnosti (dinamici) polinatora kroz sezone, uočen je porast broja jedinki medonosne pčele i opadanje broja jedinki solitarnih pčela.Rezultati dobijeni Man-Vitnijevim U-testom pokazuju da je nastepskim fragmentima koji imaju niži udeo suncokreta u predelu zastupljeno više jedinki i vrsta bumbara. Istim testom je dobijen rezultat da je na stepskim fragmentima sa visokim udelom suncokreta ima više jedinki medonosne pčele. Vilkoksonovim testom sume rangova je pokazano da su jedinke i vrste bumbara zastupljenije na stepskim fragmentima nakon cvetanja suncokreta, za vreme cvetanja suncokreta na stepskim fragmentima je registrovano više jedinki Apis mellifera, osolikih muva i solitarnih pčela. Modeli regresionih analiza linearnih mešovitih modela su pokazali da se sa porastom udela suncokreta u predelu smanjuje broj jedinki divljih pčela i jedinki i vrsta bumbara. Sa porastom udela polu-prirodnih staništa u predelu i većom cvetnom pokrovnosti, povećava se udeo jedinki i vrsta osolikih muva.This paper shows distribution, dynamic and pollinator diversity Hymenoptera - Apiformes (Anthophila) and Diptera (Syrphidae) in semi-natural habitats and in sunflower crops in Vojvodina agroecosystems. Around each of 16 selected steppe fragments, habitat types were mapped to test how do landscape structure affects pollinator diversity and abundance in semi natural habitats and in sunflower crops. Based on the results obtained by mapping, seven study sites with high % of sunflower like mass flowering crops, and eight study sites with no or low % of mass flowering crops are selected. In total, there were 114 species from 6 families from order Hymenoptera-Apiformes: Andrenidae, Apidae, Colletidae, Halictidae, Melittidae and Megachilidae, and 11 species from order Diptera (Syrphidae). Insects from families: Andrenidae, Apidae, Colletidae and Halictidae were distributed on all study sites, while insects from family Megachilidae were distributed almost on all study sites (15 sites). At least only on five study sites were distributed insects from family: Colletidae and Melittidae. Hoverflies were distributed on all study sites. Kruskal-Wallis H test shows that an all three seasons (2011., 2012., 2013.) in semi natural habitats wild bees species were most abundant, followed by hoverfly species, and bumblebee species at the end. Same test shows that in all three seasons in semi natural habitats individuals of hoverflies were more abundant than individuals of honey bees, wild bees and individuals of bumblebees, which were least abundant. Friedman test shows differences in densities of pollinator through the seasons, and these results shows increasing in Apis mellifera densities and decline of wild bees densities through seasons. Man-Whitney U-test shows that there were more species and individuals of bumble bees in semi-natural habitats which landscapes are without or low % of sunflower. Same test shows that there were more individuals of honey bees in semi-natural habitats which landscapes have high % of sunflower. Wilcoxon signed-rank test shows that in semi-natural habitats species and individuals of bumblebees were more abundant after blooming sunflower, while species and individuals of wild bees as well as individuals of hoverflies and Apis mellifera were more abundant during blooming sunflower. Linear mixed-effect model shows that with increase of % of sunflower in landscape number of individuals of wild bees and species and individuals of bumblebees decreasing, and individuals of hoverflies increasing. With an increase of % of semi natural habitats and increase of flower cover, abundance and species of hoverfliesincreases.
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Morandin, Lora A. "Wild bees and agroecosystems /." Burnaby B.C. : Simon Fraser University, 2005. http://ir.lib.sfu.ca/handle/1892/2386.
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Thesis (Ph.D.) - Simon Fraser University, 2005.Theses ( Dept. of Biological Sciences) / Simon Fraser University. Includes bibliographical references. Also issued in digital format and available on the World Wide Web.
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Pearce, April Marie. "Pollinators of slender white prairieclover." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/pearce/PearceA0808.pdf.
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Slender white prairieclover (Dalea candida) is a perennial angiosperm, grown at Bridger plant materials center (BMPC) for reclamation purposes. Interest in the pollinators and pests of this plant developed at BPMC following the death of a 5year old stand. The objectives of these experiments were to (1) determine the diversity and identify the potential pollinators on D. candida and other cultivated and non-cultivated angiosperm species using sweep samples and pan traps; (2) determination of pollen load size and composition of individual insects collected on angiosperm plant species; (3) use of different size exclusion cages to determine the general sizes of insects most important for pollination of D. candida at BPMC; and (4) determine the composition of the community of cavity-nesting Hymenoptera species at BPMC by using trap nests. The overall diversity of BPMC was much higher than expected in a monoculture agriculture area, with a total of 102 Hymenoptera taxa collected. Hill\'s #2 index was used to determine the diversity of different angiosperm plants and revealed that D. candida had the highest diversity. Analysis of pollen loads via the proportion of \"pure\" vs. mixed loads (PBP) and mean proportion of conspecific pollen (PCP) revealed conflicting results between the two measures, but there does appear to be some floral constancy occurring, especially in D. candida. Kruskal-Wallis tests of differences in exclusion cage treatments revealed that there are differences in pollination efficacy and the size subset allowed to reach the flowers. Emergences from trap nests revealed differences in the trap nesting community at BPMC and actual pollinator collections in the field.
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Greeson, Kimberley M. "Of Pollinators and Forests| A Multispecies Ethnography of the Biopolitical Culture of Pollinators in Hawai'i." Thesis, Prescott College, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10288361.
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Due in part to its geographic isolation and unique climate, Hawai‘i has a high number of endemic species and is considered a biodiversity hotspot. At the same time, these characteristics make Hawai‘i vulnerable to species loss. To protect endangered species, conservationists focus on preserving Hawai‘i’s native ecosystems through invasive species control and habitat restoration. Native forests are central to Hawai‘i’s watershed, provide habitat for endemic pollinators, and foster bioculture. Pollinators are integral for ecosystem health as well as for human spaces, and worldwide pollinators have been on the decline. Since pollinators and their flowering counterparts are embedded in human lives, this research challenges traditional conservation approaches by contextualizing more-than-human entanglements within social, political, and cultural milieu. The purpose of this work is to draw from posthumanism, new materialism, and indigenous discourse to examine the biopolitical issues in which Hawaii’s endemic pollinators situate to re-envision questions and ethics of conservation. The researcher followed endemic pollinators through native forests to explore the entangled relationship between humans, pollinators, and forests examining the question, what is the biopolitical culture of endemic pollinators in Hawai’i? This multi-sited, multi-method research used a mix of autoethnography, participant observations and interviews, visual data, and archival and biocultural accounts to articulate emergent findings. The findings of this dissertation discuss the nuances of multispecies entanglements and mattering, politics of biological conservation and extinction, and material-discursive understandings of place. This study suggests human/more-than-human encounters are grounded in reciprocity and responsibility and co-create place.
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Maine, Josiah J. "TROPHIC ECOLOGY OF INSECTIVOROUS BATS IN AGROECOSYSTEMS." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1599.
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Land-use change is a leading cause of biodiversity loss and ecosystem service degradation worldwide, but these changes do not affect all organisms equally. Understanding the factors that influence resistance to environmental change is vital for informed conservation. In particular, dietary generalists may withstand environmental change better than specialists due to their ability to exploit variable resources. Bats are voracious predators of insects, but vary widely in their degree of dietary specialization. In Chapter 1, I analyze the effect of land cover and morphology on dietary diversity and the two most common prey items (Lepidoptera and Coleoptera) of bats, selecting important independent variables using phylogenetic generalized least squares (PGLS) and model selection. Dietary diversity increased with increasing amount of cropland near the study area, consumption of Lepidoptera decreased with increasing habitat diversity, and consumption of Coleoptera decreased with increasing distance from the equator. Biodiversity (and hence, prey diversity) is expected to decrease with agricultural intensity, but the observed pattern suggests that dietary specialists may avoid agricultural habitats due to lack of preferred prey. Dietary specialists may thus be increasingly at risk as agricultural intensity increases around the world, and it is essential that we continue to document their ecological roles and the services they provide to society
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Ellis, Ciaran R. "Valuing wild pollinators for sustainable crop production." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/22327.
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This thesis looks at the role of wild pollinators in providing services to crops. Two data chapters (2 and 3) are accompanied by a modelling chapter (4) which build on the findings of the field studies. The thesis ends with an overview of the trends in pollinator populations and how these relate to the needs of farmers in the UK (chap-ter 5). It is often assumed that commercial pollinators are appropriate substitutes of wild pollinators on farms; however this view neglects the differing roles that particular pollinator taxa might play in providing pollination services. For example, crops with a long growing system may require multiple pollinators to ensure pollination throughout the season. Strawberries in Scotland have an extremely long growing season, flowering from April to August. Chapter 2 presents a study showing season-al complementarity between different pollinating taxa across strawberry farms in Scotland. Pollinators of strawberries also differed in their responses to weather pa-rameters indicating that preserving multiple pollinator taxa could ensure yields un-der different weather scenarios. The requirements of a long-growing season and ad-verse weather may be specific to strawberry production in Scotland, but the valua-tion of multiple taxa can be generalised to systems with differing needs, and also to different ecosystem services. Wild bees are not only valuable for providing complementary services to commercial pollinators, but are also valuable in the longer term as it is unknown whether com-mercial pollinators will be available in the future. There are threats to the supply of honeybees which have already triggered price rises; such supply shocks could force farmers to leave production or to seek other ways of providing pollination, including supporting wild pollinators. However farm management pressures, in particular pes-ticide use, could threaten the ability of wild pollinators to continue to support crop production. The interplay of pesticides and pollination is discussed in chapter 3 and 4. Chapter 3 presents an experiment undertaken on soft-fruit farms which had and had not used the neonicotinoid, thiacloprid, and shows that nests exposed to thia-cloprid had higher worker mortality, and lower male production than those at con-trol farms. This has implications both for pollination services now, as worker mor-tality will reduce the number of bees visiting farms, and also for the maintenance of future pollination services through decreased reproductive capacity of exposed nests. Chapter 4 uses a theoretical model to link pesticide use and habitat use to pollina-tion services, and shows that the use of commercial pollinators could mask the de-cline in wild populations, making local extinctions more likely. Chapter 5 sets out the status and extent of pollinators in the UK, along with popu-lation trends, trends in habitat and trends in pesticide use to provide an overview of how well pollination services are likely to meet the ongoing needs of crop farmers.
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Perreault, Jonathan M. "Casting activity of Lumbricid earthworms from temperate agroecosystems." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82405.
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Earthworms are well known for their casting and burrowing activities which improve soil structure and soil fertility. However, earthworm populations in temperate regions exhibit patchy distribution in space and time. This makes it difficult to predict how earthworm activities may influence paedogenesis and nutrient cycling processes at the ecosystem level. The main objective of this study was to determine the spatiotemporal dynamic of surface cast production of two earthworm species, Aporrectodea turgida and Lumbricus terrestris, on the row-interrow scale in a temperate soybean agroecosystem. Our observations demonstrated that casting activity was synchronous with plant growth. More casts were also found in the row intercepts compared to the interrow ones. Both the spatial and temporal variations are thought to be caused by the microclimate found under the plant canopy, verifying results from controlled laboratory studies that show casting activity to be controlled by soil temperature and moisture. These results suggest a possible mutualism between earthworm and plants in cultivated temperate soybean agroecosystems, but this remained to be confirmed.
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Quezada, Jorge Francisco Perez. "Carbon flux patterns in agroecosystems of northern Kazakhstan /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Gibson, Stephen. "Geographical variation in insect pollinators of generalist Asteraceae." Thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/26665.
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Kaczorowski, Rainee L. "Nectar in Nicotiana : pollinator associations, sources of variation, and evolutionary consequences /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4813.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 25, 2007) Vita. Includes bibliographical references.
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Fabrizzi, Karina Paola. "Microbial ecology and C and N dynamics in Agroecosystems." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/241.
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Carruthers, Jonathan Michael. "Nutritional resources for pollinators from mass-flowering crop cultivars." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3680.
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The scarcity of flowers to provide dietary nectar and pollen is a key driver of recent declines in pollinators in agricultural areas, but the planting of mass-flowering crops enhances resources available to pollinators during parts of the year. This thesis investigates the nutritional resources provided for insect pollinators from various cultivars of two mass-flowering crops: short rotation coppice willow (Salix species) and oilseed rape (Brassica napus L.). Willow cultivars vary in the numbers of flowers produced per plant, as well as in the quantity of nectar sugar secreted by those flowers. There were neither qualitative nor quantitative differences in pollen production between the cultivars. Foraging insect pollinators showed preferences for cultivars with more rewarding flowers. Oilseed rape flowers of different cultivars produced a mass of nectar sugar that varied by up to three fold in mass when grown in a glasshouse. Cultivars differed in the size of their flowers, but neither flower size nor the seed yields they produced in industry trials were correlated with their nectar yields. When plants were grown in field conditions, differences between oilseed rape cultivars in nectar production were also present, although less pronounced. The weights of bumble bee (Bombus terrestris L.) colonies diverged after two weeks when restricted to foraging on plots containing either a high or a low nectar yielding cultivar. The findings indicate that efforts to breed and to plant more widely the more rewarding cultivars of mass-flowering crops would enhance the resources available to pollinators in spring. As this is a critical time for pollinators, the extra resources could aid their survival and lead to more robust populations.
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Paisley-Jones, Claire E. "Monitoring Agroecosystem Biodiversity Using Bioacoustics and Remote Recording Units." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316534540.
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Povilaitis, Virmantas. "Aspects of Cereal Yield Formation in Agroecosystems of Different Intensity." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20120507_172609-99074.
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The object of study – spring barley (Hordeum vulgare L.) and winter wheat (Triticum aestivum L.). Research tasks: 1. To investigate the effect of growing intensity, applying fertilisers according to normative for target yield, on spring barley and winter wheat leaf index, biomass and grain yield formation. 2. To quantitatively assess accumulation of nitrogen and carbon in the biomass during vegetation. 3. To explore the effect of water and nitrogen induced stresses on productivity of photosynthesis and to evaluate feasibility of DSSAT v4.0.2.0 model for the diagnosis. 4. To estimate likely effect of climate change on winter wheat and spring barely yield.Darbo uždaviniai: 1. Ištirti skirtingo auginimo intensyvumo, tręšiant pagal normatyvus planuojamam derliui, poveikį vasarinių miežių ir žieminių kviečių lapų indekso, biomasės ir grūdų derliaus formavimuisi. 2. Nustatyti kiekybinius azoto ir anglies kaupimosi biomasėje pokyčius vegetacijos metu. 3. Ištirti vandens ir azoto trūkumo sukeltų stresų pasireiškimą migliniuose javuose ir įvertinti galimybes juos diagnozuoti modeliu DSSAT v4.0.2.0. 4. Įvertinti tikėtiną klimato kaitos poveikį žieminių kviečių ir vasarinių miežių derlingumui. Tyrimų objektas – vasarinis miežis (Hordeum vulgare L.), žieminis kvietys (Triticum aestivum L.).
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Herman, John. "Herpetofaunal communities in agroecosystems : the effect of farm management style /." See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1114016439.
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Font, Moragón Carme. "Mathematical models for energy and landscape integrated analysis in agroecosystems." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/399906.
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Els models matemàtics s'utilitzen per explicar fenòmens naturals. Com que els fenòmens naturals són molt complexes, per tal d'aprofundir en el seu comportament i ser capaç de fer prediccions sobre ells, es necessita passar per un procés de simplificació. En el procés de creació del model, el sistema es tradueix a llenguatge matemàtic que permet l'estudi del sistema des d'un nou punt de vista. En aquesta tesi, es consideren models estadístics per estudiar el comportament dels agroecosistemes a diferents escales espacials.
L'objectiu d'aquest treball és estudiar la relació entre fluxos d'energia, canvis de cobertes del sòl, la funcionalitat del paisatge i la biodiversitat que subjau en els agroecosistemes. Per a això, es proposen models basats en tals matèries. Les principals unitats d'anàlisi seran les cobertes del sòl, quan treballem a escala regional, i els usos del sòl, a escala local.
En el segon capítol, es presenta un model de pertorbació-complexitat intermèdia (IDC) dels paisatges culturals. Aquest enfocament té com a objectiu avaluar com els diferents nivells de pertorbacions antropogèniques sobre els ecosistemes afecten la capacitat d'acollir la biodiversitat en funció de l'heterogeneïtat d'usos sòl. S'aplica a l'illa de Mallorca, enmig de la zona activa de la biodiversitat mediterrània, a escala regional i de paisatge.
El model utilitza la pertorbació exercida pels agricultors que alteren la producció primària neta a través del canvi d'usos del sòl, així com l'eliminació d'una part d'ella, juntament amb l'índex de Shannon-Wiener de la diversitat d'usos del sòl. El model es prova en un disseny experimental a dues escales al llarg de tres punts de temps. La riquesa d'espècies d'aus nidificants i hivernants, preses com a indicador de la biodiversitat, s'utilitza en una anàlisi factorial exploratori.
Seguint la idea presentada en el segon capítol, en el tercer capítol es presenta un mètode per descriure la relació entre els indicadors d'heterogeneïtat d'usos del sòl, i l'apropiació humana de la producció primària neta en una regió determinada. Aquestes quantitats són vistes com a funcions del vector de proporcions de les cobertes de sòl, que al seu torn es tracta com un vector aleatori els valors del qual depenen de la unitat de terreny que s'observa.
Presentem el mètode suposant, en primer lloc, que el vector de proporcions segueix una distribució uniforme en el símplex. Després, considerem com a punt de partida un conjunt de dades mostals, de manera que primer hem d'obtenir una estimació de la seva distribució de probabilitat teòrica, i en segon lloc, generem una mostra de grans dimensions seguint la distribució estimada. Apliquem aquest procediment a dades de l'illa de Mallorca en tres moments de temps diferents.
L'objectiu principal aquí és calcular el valor esperat de la diversitat del paisatge com a funció del nivell d'apropiació humana. Aquesta funció està relacionada amb l'anomenada hipòtesi d'energia i espècies, i amb l'hipòtesi de la Pertorbació Intermèdia.
Finalment, el quart capítol està dedicat a tractar els processos interns dels agroecosistemes. Per a aquest propòsit, es proposa un graf que representa el patró de fluxos d'energia en un agroecosistema. Utilitzem aquest graf per calcular el nivell d'emmagatzematge d'energia dins de l'agroecosistema, així com la informació inclosa en aquesta xarxa de fluxos, a escales tant local com de paisatge.
Per tant, es proposa un model d'anàlisi integrat d'energia i paisatge (ELIA) que avalua tant la complexitat dels bucles d'energia interna, com la informació continguda en tota la xarxa de fluxos d'energia soci-metabòliques, per tal de correlacionar aquesta interacció d'informació energètica amb l'estructura funcional del paisatge. A l'annex, es suggereix una millora de l'indicador d'informació. ELIA es prova en el Vallès, a la Regió Metropolitana de Barcelona.Mathematical models are used to better explain natural phenomena. Since natural phenomena are very complex, in order to delve into their behaviour and be able to do predictions over them, a simplification process of such systems is needed. In the process of creating the model, the system is translated into mathematical language that allows the study of the system from a new point of view. In this thesis, statistical models are considered to study the behaviour of agroecosystems at different spatial scales. The aim of this work is to study the relation between energy flows, land cover changes, landscape functionality and the biodiversity that underlies in agroecosystems. For this, models based on such matters are proposed. The main units of analysis will be the land covers, when we work at regional scale, and the land uses, at local scale. In the second chapter, an intermediate disturbance-complexity model (IDC) of cultural landscapes is presented. This approach is aimed at assessing how different levels of anthropogenic disturbance on ecosystems affect the capacity to host biodiversity depending on the land matrix heterogeneity. It is applied to the Mallorca Island, amidst the Mediterranean biodiversity hotspot, at regional and landscape scales. The model uses the disturbance exerted by farmers altering the Net Primary Production (NPP) through land use change, as well as removing a share of it, together with Shannon-Wiener index of land use diversity. The model is tested with a twofold-scalar experimental design of a set of landscape units along three time points. Species richness of breeding and wintering birds, taken as a biodiversity proxy, is used in an exploratory factor analysis. Following the idea presented in the second chapter, in the third chapter we present a method to describe the relation between indicators of the land matrix heterogeneity, and the human appropriation of the net primary production in a given region. These quantities are viewed as functions of the vector of proportions of the different land covers, which is in turn treated as a random vector whose values depend on the particular small terrain cell that is observed. We illustrate the method assuming first that the vector of proportions follows a uniform distribution on the simplex. We then consider as starting point a raw dataset of proportions for each cell, for which we must first obtain an estimate of its theoretical probability distribution, and secondly generate a sample of large size from it. We apply this procedure to real historical data of the Mallorca Island in three different time points. The main goal here is to compute the mean value of the land covers diversity as a function of the level of human appropriation of net primary production. This function is related to the so-called Energy-Species hypothesis and to the Intermediate Disturbance Hypothesis. Finally, fourth chapter is devoted to deal with agroecosystems internal processes. For this purpose, a graph to represent the pattern of energy flows in an agroecosystem is presented. We use this graph model to calculate the level of energy storage within the agroecosystem provided by its ‘internal feedback’, as well as the information embedded in this network of flows, at local and landscape scales. Thus, we propose an Energy-Landscape Integrated Analysis (ELIA) model that assesses both the complexity of internal energy loops, and the information held in the whole network of socio-metabolic energy fluxes, so as to correlate this energy-information interplay with the functional landscape structure. In the annex, an improvement of the information indicator is suggested. ELIA is tested in the Vallès County of the Barcelona Metropolitan Region.
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Monsen, Katie Lenore. "Managing nitrogen in organic vegetable agroecosystems on California's Central Coast /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
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Dyck, Amber. "Ditch Management in Agroecosystems: From Water Quality to Frog Health." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40969.
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Agriculture ditch management (i.e. removal of vegetation and/or sediments) may disturb native wildlife, such as amphibian bioindicator species. The objective of this thesis was to determine whether ditch management affected northern leopard frogs (Lithobates pipiens). Twelve embryo and tadpole health endpoints were compared in vegetated and managed (treeless or dredged) ditches using in situ cages in 2018 and 2019, while water quality was monitored. The managed treatment did not negatively affect frog health compared to the vegetated treatment. The significantly faster development and larger body size due to warmer water temperatures at the managed treatment were likely advantageous. The water quality was typical of the region regardless of the ditch treatment and the pesticide mixture detected had limited toxicity. The main effects of the studied ditch managements on resident L. pipiens (and potentially other amphibians) appeared sub-lethal, likely beneficial, and mainly the result of temperature differences. Although poorer embryo health was observed at the vegetated treatment, it was likely unrelated to ditch management and possibly due to high specific conductivity causing premature hatching and mortality. Ditch management may be less important for frog health than the surrounding land use, and efforts should be directed at increasing suitable habitat for amphibians in agroecosystems. La gestion des fossés agricoles (plus spécifiquement l'élimination de la végétation des bandes riveraines et /ou le dragage des sédiments) peut perturber la faune indigène, comme les espèces bio-indicateurs d'amphibiens. L'objectif de cette thèse était de déterminer si la gestion des fossés affectait la grenouille léopard du Nord (Lithobates pipiens). Douze paramètres d'évaluation de la santé des embryons et des têtards ont été comparés dans des fossés végétalisés et gérés (sans arbres ou dragués) à l'aide de cages expérimentales in situ en 2018 et 2019, pendant que la qualité de l'eau a été suivie. Le traitement géré n'a pas eu d'effets négatifs sur la santé des grenouilles par rapport au traitement végétalisé. Le développement beaucoup plus rapide et la taille corporelle plus grande en raison des températures plus chaudes de l'eau lors du traitement géré étaient probablement avantageux. La qualité de l'eau était typique de la région quel que soit le traitement du fossé et le mélange de pesticides détecté avait une toxicité limitée. Les principaux effets de la gestion des fossés étudiés sur L. pipiens résidents (et potentiellement d'autres amphibiens) semblaient sublétaux, probablement bénéfiques, et résultaient principalement de différences de température. Bien que la santé des embryons ait été moins bonne lors du traitement végétalisé, elle n'était probablement pas liée à la gestion des fossés et pourrait être due à une conductivité spécifique élevée entraînant une éclosion prématurée et la mortalité. La gestion des fossés peut être moins importante pour la santé des grenouilles que l'utilisation des terres environnantes, et les efforts de protection devraient être dirigés vers une augmentation générale de l'habitat approprié pour les amphibiens dans les agroécosystèmes.
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Herman, John Edward. "Herpetofaunal Communities in Agroecosystems: The Effect of Farm Management Style." University of Toledo / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1114016439.
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Whalen, Joann K. "Effects of earthworms on nitrogen flux and transformations in agroecosystems /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487949508372199.
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Sjödin, N. Erik. "Pollinating insect responses to grazing intensity, grassland characteristics and landscape complexity : behaviour, species diversity and composition /." Uppsala : Dept. of Ecology, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200755.pdf.
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Prieto, Roberto. "The role of earthworms in nitrous oxide emissions from forage agroecosystems." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103783.
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Nitrous oxide (N2O) emission from agricultural soils contributes to the greenhouse effect, depletion of the ozone layer, and acid rain formation. In laboratory studies, soil in contact with earthworms had significantly higher N2O production than soil devoid of earthworm activity. The elevated N2O production occurs via activation or priming of nitrifying and/or denitrifying microorganisms. Yet, field scale experiments have been inconclusive with respect to N2O fluxes attributed to earthworms. The objectives of this thesis were in the field to (1) determine the effect of elevated anecic and endogeic earthworm populations on N2O fluxes from legume and non-legume enclosures, and in the laboratory to (2) qualify the denitrification community and (3) quantify the denitrification rate of earthworm-related structures including the gut, casts, burrows and middens of the anecic Lumbricus terrestris. In the field study, elevated earthworm populations increased N2O fluxes significantly (P<0.05) in legume but not in non-legume enclosures. Anecic species appeared to have a greater effect on N2O fluxes. The linear regression model of the flux data and number of earthworms added was significant (P<0.05); on average earthworms emitted 335 ng N2O m-2 h-1 from the legume enclosures when soil moisture exceeded 60% water-filled pore space. In the laboratory study, a 454 pyrosequencing analysis on the diversity and phylogeny of bacterial nosZ gene fragments (encoding N¬2O reductase) revealed a set of 39 unique OTUs, of which 14 were found only in the earthworm gut. The earthworm gut appears to have a unique set of endemic denitrifying bacteria. An acetylene block assay revealed that the earthworm itself had the greatest denitrification rate of 2.67 g N2O-N g soil-1 h-1, which was significantly (P<0.05) greater than bulk soil and other earthworm structures except fresh casts. Fresh casts had a denitrification rate of 0.94 g N2O-N g soil-1 h-1 which was significantly (P<0.05) greater than the rate of aged cast and bulk soil. The set of unique gut denitrifiers is highly active due to the favourable conditions in the gut, including anoxia and quality substrate. When fresh, anecic earthworm related structures are important "hot spots" favouring the activity of soil denitrifiers. This thesis demonstrates the importance of earthworm-denitrifier interactions for N2O emissions, particularly in legume-based agroecosystems, which should be considered when developing predictive models of greenhouse gas emissions from agricultural soils.Les émissions d'oxyde nitreux (N2O) provenant de sols agricoles contribuent à l'effet de serre, à la destruction de la couche d'ozone et à la formation de pluies acides. Des études en laboratoire ont démontré que, lorsque le sol est en contact avec des vers de terre, celui-ci présente des niveaux plus élevés de flux de N2O que lorsqu'il n'y a pas de verres de terre présents. Un taux élevé de N2O se produit lorsque les micro-organismes nitrifiants et/ou dénitrifiants sont activés. Pourtant, les études publiées sur les essais aux champs n'ont pas été concluantes quant aux niveaux de N2O attribuables à la présence de vers de terre. Les objectifs de ce mémoire étaient : (1) sur le terrain, de déterminer l'incidence des quantités élevées de vers de terre anéciques et endogés sur les niveaux de flux de N2O dans les chambres avec et sans légumineuses, (2) en laboratoire, de définir les agents bactériologiques dénitrificateurs, et (3) de quantifier le taux de dénitrification des structures associées aux vers de terre, incluant intestins, turriculés, tubes et tertres du ver de terre anécique Lumbricus terrestris. Selon les études effectuées sur le terrain, lorsqu'il y avait une présence accrue de vers de terre, les niveaux de N2O augmentaient de façon importante (P<0,05), mais seulement dans les chambres avec des légumineuses. Les espèces anéciques semblaient avoir un effet plus important sur les émissions de N2O. Le modèle de régression linéaire des données relatives aux niveaux de N2O et à la quantité de vers de terres ajoutés était significative (P<0,05) ; en moyenne, les vers de terre émettaient 335 ng N2O m-2 h-1 lorsque l'humidité du sol dans les chambres avec légumineuses excédait 60% de l'espace poral irrigué. Lors de l'étude en laboratoire, une analyse de 454 pyroséquençage portant sur la diversité et la phylogénie des fragments génétiques de la bactérie nosZ (codification de réductase de N2O) a révélé un ensemble de 39 unités taxonomique opérationel (UTOs) unique, dont 14 identifiées dans les intestins du ver de terre. Les intestins semblent contenir un ensemble unique de bactéries dénitrificatrices endémiques. Une analyse au blocage à l'acétylène a démontré que le ver de terre lui-même présentait le potentiel le plus élevé de dénitrification, soit 2,67 µg N2O-N g sol-1 h-1, valeur nettement supérieure (P<0,05) à celles du sol brut et des autres structures de vers de terre, à l'exception des turriculés frais. Les turriculés frais indiquaient un taux moyen de dénitrification de 0,94 µg N2O-N g sol-1 h-1, donc plus élevé (P<0,05) que le taux de turriculés vieillis et du sol brut. L'ensemble distinct de dénitrificateurs intestinaux est très actif de par leurs conditions favorables dans les intestins, dont l'anoxie et le substrat de qualité. Lorsque les structures de vers de terre anéciques sont fraîches, celles-ci deviennent des endroits propices favorisant la dénitrification du sol. Ce mémoire affirme l'importance de l'interaction entre les verres de terre et les microorganismes dénitrifiants quant aux émissions de N2O, en particulier dans les agroécosystèmes de légumineuses. Ces interactions devraient être prises en compte lors du développement de modèles de prévision des émissions de gaz à effet de serre provenant des sols agricoles.
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Sey, Benjamin Kweku. "Carbon dioxide and nitrous oxide production from corn and soybean agroecosystems." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102726.
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Globally, an estimated 25% of the CO2 and 90% of the N2O is believed to come from agroecosystems. The objective of this study was to investigate the dynamics of the below-ground CO 2 and N2O concentrations and efflux in corn and soybean systems. In our field study, changes in the below-ground concentrations of CO 2 and N2O were closely related to seasonal changes in soil moisture, with the first two months of the growing season being particularly critical to the production of these gases. Tillage significantly increased CO2 content in the soil profile, however, this effect was greater in the soybean plots than in the corn plots. In our greenhouse studies, an average of about 79% of the soil respiration in corn came from rhizosphere respiration, compared to an estimated 58% in the case of soybean. Specific rhizosphere respiration was significantly higher in soybean (0.29 mg C g -1 root h-1) than corn (0.09 mg C g-1 root h-1), which supports previous observations made with regards to slower-growing plants (e.g. soybean) having relatively higher root respiration than faster growing plants. We observed a nonsignificant difference between N2O efflux in the soybean-planted soil and unplanted bulk soil, which is in contrast to the perception that legumes could stimulate more N 2O production from the soil by increasing the N pool through N 2 fixation. While corn had the greatest uptake of fertilizer N, N 2O efflux in corn pots was higher (2.84 mug N pot-1 h-1) than the soybean pots (0.06 mug N pot-1 h-1). In the laboratory setting, denitrification in the microaggregates proceeded at about 4.4 to 39.6 times higher rate than in large macroaggregates, small macroaggregates or the bulk soil, and showed the greatest response to high moisture levels (80% WFPS).
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Keller, Armin. "Assessment of uncertainty in modelling heavy metal balances of regional agroecosystems /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13944.
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Stinson, Graham. "Assessment of carbon sequestration in representative forests and agroecosystems in Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0016/MQ49451.pdf.
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Abson, David James. "Landscape heterogeneity, farmland birds and economic resilience in UK lowland agroecosystems." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539712.
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Wade, Jordon. "Soil Health and Nutrient Dynamics in Agroecosystems of the Midwestern US." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555334900543422.
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Lindsey-Robbins, Josephine C. "Effects of Detritivores on Nutrient Dynamics and Corn Biomass in Agroecosystems." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1561588059374285.
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Athey, Kacie J. "Exploring Predator-Prey Interactions in Agroecosystems through Molecular Gut-Content Analysis." UKnowledge, 2017. http://uknowledge.uky.edu/entomology_etds/35.
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Generalist predators can contribute to vital ecosystem services by potentially inducing trophic cascades as natural enemies of pests in agroecosystems. As the human population of the world gets larger, we need to produce more food on ever-smaller swaths of available land relying on ecosystem services, in the form of pest control, that may contribute to agricultural sustainability. Teasing apart the exact trophic linkages between predators and prey is a vital first step and essential to uncovering which predators are inducing trophic cascades and should be enhanced through conservation biological control.
Combined with ecological experimentation, the main tool used throughout my research to identify trophic linkages is molecular gut-content analysis. I began by investigating mass sampling techniques and found they do not cause contamination in gut-content analysis and may be a simple method for collecting large numbers of cryptic predators for use in determining trophic linkages. Additionally, my research uncovered trophic interactions between stink bugs and generalist predators at multiple scales. Overall, I successfully designed molecular methods to investigate relationships between agricultural pests and generalist predators. A multi-year field study uncovered low predation on stink bug pests in contrast to previous research suggesting that generalist predators were contributing highly to biological control. This research highlights the need for replicated studies before making broad conservation biological control decisions. Although generalist predators were not consuming stink bugs in large numbers, my field cage study showed evidence of superfluous killing by spiders on adult stink bugs, highlighting the need to combine ecological studies with molecular methods to understand consumptive and non-consumptive effects on prey items. Gut-content analysis showed no evidence of consumption, but the field cage study allowed me to uncover the complicated relationships between spiders and stink bugs. In addition, I showed an invasive species can be detected in new areas through molecular gut-content analysis of predators before other sampling methods.
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Hausmann, Sebastian Lars [Verfasser]. "Interactions of pollinators and nectar-occupying yeast communities / Sebastian Lars Hausmann." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1177152606/34.
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Banza, Paula. "Investigating the importance of Nocturnal Lepidoptera as Pollinators: a network approach." Master's thesis, Universidade de Évora, 2011. http://hdl.handle.net/10174/15569.
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A polinização pode ser entendida ao nível da comunidade ecológica como uma rede de interacções mutualistas entre dois níveis tróficos, já que a maior das plantas utiliza múltiplos polinizadores e vice-versa.
Nos últimos dez anos houve um crescente interesse nas redes de polinização e muitas têm sido estudadas e descritas cobrindo uma ampla variedade geográfica e ecológica. Contudo o estudo dos polinizadores nocturnos ao nível da comunidade, tem sido descurado e praticamente não existem redes nocturnas de polinização descritas na literatura especializada.
Os Lepidópteros nocturnos são talvez dos mais comuns polinizadores nocturnos e desempenham um papel muito importante nas comunidades biológicas também como presas e herbívoros.
Neste estudo descrevem-se dois tipos de redes de polinização: transferência de pólen e visitação floral; também se identificam alguns lepidópteros polinizadores nocturnos e constrói-se a primeira rede nocturna planta - polinizador para Portugal. As propriedades das redes de polinização estudadas revelaram um valor abaixo do esperado para o aninhamento ponderado e um elevado número de ligações por espécies, o que se reflecte nos valores elevados da diversidade e regularidade das interacções. O grau de especialização é elevado no caso da rede de transferência de polén mas muito baixo no caso da rede de visitação floral.
A comprensão da ecologia das borboletas nocturnas é muito importante para a sua conservação e também para a preservação da polinização enquanto serviço dos ecossistemas; ABSTRACT:Pollination can be viewed at the level of an entire ecological community as a network of mutualistic interactions between two trophic levels as most plants utilise multiple pollinators and vice versa.
Over the last ten years there has been growing interest in pollination networks and pollination webs have been studied covering a variety of geographical and ecological settings. However, nocturnal pollination as a community-level phenomenon has been overlooked and there are almost no published nocturnal pollination networks.
Moths are probably the most common nocturnal pollinators and they play a significant role in many communities as they are also herbivores and prey.
In this study two types of networks have been described: pollen transfer and flower visitation, nocturnal Lepidoptera pollinators have been identified and the construction of Portugal´s first nocturnal plant-pollinator network has been described. The main properties studied revealed a lower nestedness than expected when compared with other pollination networks, high number of interactions between species reflected on the high values of interaction evenness and interaction diversity; specialization was high for pollen transfer network and low for flower visitation network.
Understanding the ecology of moths is important for the conservation of moth and ecosystem services of pollination.
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Nicholson, Charles C. "No Farm Is An Island: Pollinators And Pollination In Agricultural Landscapes." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/985.
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Productive, resilient and sustainable agricultural systems are required to meet the immediate needs of a burgeoning human population, while avoiding ecosystem collapse. Agriculture provides food, fiber, fuels and other products for our current population of 7 billion and is still the major livelihood for 40% of people worldwide. By replacing natural habitat and employing chemical inputs, agriculture also negatively impacts biodiversity and impairs the provision of ecosystem services. This poses a challenge for agriculture as these impacted services are often those required for high yielding and high-quality crop production. Evidence is accumulating that agricultural management can safeguard biodiversity and ecosystem services while maintaining production, but critical questions remain concerning how management actions are shaped by broader landscape pattern and how these actions influence service-providing organisms across space and time.
Through a combination of observational, experimental and modeling approaches, my dissertation examines relationships between management actions, landscape pattern and service-providing organisms using crop pollination by wild bees as a model system. First, I investigate how local management and landscape pattern interact to affect pollination services and the abundance and diversity of native bees in Vermont, USA. I then use two established models of pollinator foraging to investigate whether one popular intervention, enhancing floral resources, improves crop visitation, and whether pollinator traits and landscape pattern influence this effect. Next, I use a national data set of native bee diversity to test whether habitat enhancements increase taxonomic and functional diversity of native bee communities. Finally, I investigate whether resource continuity provided by consecutively blooming crops benefits wild bee communities. These four chapters contribute ecological knowledge of plant-animal interactions in anthropogenic landscapes. My findings also provide land managers with clear information about the effects of landscape conservation and farm management on crop pollinators.
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Dalton, Naomi Jane. "Pollinators, plants and people : a transdisciplinary study of rare species conservation." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.688353.
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Translocation is widely used to counter the fragmentation and decline of populations of species at risk, in order to enhance their survival prospects. Additionally, translocation is used in ecological restoration to introduce taxa conferring strong positive influence, with the potential to recreate communities and reinstate functional roles. Conservation of species by translocation is considered high risk and high cost; therefore ecologists need to understand how success can be maximised. In this thesis, I test the community level impacts of a rare plant and evaluate the effectiveness of single-species conservation for bottom-up restoration. To do this I study the effect a rare plant species, Sium latifolium, has on pollinator communities and find a strong local effect, but detect no population level change. I conclude that the addition of a single plant species is ineffective at providing population change. For evaluation of conservation strategies for pollinators, population level impact must be tested for, rather than assuming that they mirror the local effect. I then explore options for improving the success of species translocation, adopting methodologies from population genetics and social sciences. I test whether low genetic diversity limits the success of S. latifolium translocations, predicting that introduction survival correlates with diversity of the donor natural population. I reject this hypothesis and conclude instead that, for S. latifolium, ecological conditions determine initial success of introductions. Much experience for this resides with practitioners, therefore I use social network analysis to quantify communication between people conserving S. latifolium. I test whether a small scale network intervention (organising a meeting) can create new ties and improve knowledgeexchange through the network.
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Eriksen-Hamel, Nikita S. "The contribution of earthworm communities to nitrogen cycling in agroecosystems of Québec /." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102976.
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Earthworms have an important role in the decomposition of organic matter, mineralization of nutrients and physical mixing of soils. Despite a large number of laboratory and greenhouse-level studies investigating how earthworms modify soil properties and promote soil fertility, we lack reliable methods to scale-up and quantify earthworm contributions to nutrient cycling at the agroecosystem level. The objective of this thesis is to determine the influence of earthworm communities on nitrogen (N) transformations in soils and to quantify their contribution to nitrogen flux through soils for soybean and maize cropping systems of Quebec. Laboratory growth rates were used to predict how earthworm growth responded to seasonal fluctuations in soil temperature and moisture. The relationships between earthworm populations, soil-N pools and annual crop production were evaluated in a field experiment. When favourable conditions occurred in 2004 (temperatures <20°C, and rainfall at least once a week), a positive relationship was found between earthworm numbers and the plant available-N, including soil mineral-N, microbial biomass-N and total-N removed in soybean grain. In 2005, soil conditions were unfavourable (temperatures > 20°C and little or no rainfall) to earthworm survival and growth, and no relationship was found between earthworm populations, soil N pools and corn production. These data permitted me to make assumptions about earthworm activity and life histories under field conditions, which were used to estimate N flux through earthworm communities with two models. The models were tested for their sensitivity to varying parameter values within the range reported in the scientific literature. During a crop growing period with favourable climate conditions, a large earthworm population (100 g fresh weight biomass m-2 or greater) is predicted to cycle as much as 120 kg N ha-1. Model predictions were very sensitive to input parameters and did not correspond to the partial N budget calculated at the site. Accurate predictions of N mineralization by earthworms require more species- and site-specific parameter values. Further investigation using stable 15N isotopes as tracers would help us to follow the N transformations and evaluate the N flux mediated by earthworms at the field scale.
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Guezen, Jessica. "Past Floral Resources as a Predictor of Present Bee Visits in Agroecosystems." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/37051.
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Relying on wild bees for pollination services has become necessary as the global demand for crops dependent on animal pollination increases. If wild bee populations are to establish and persist in agricultural landscapes, there must be sufficient floral resources over time and space. This study examines the relationship between bee visits in agroecosystems and the spatiotemporal availability of floral resources over one season. I expected that landscapes with greater floral resources earlier in the season would subsequently experience more bee visits than landscapes with fewer early-season floral resources, and that the spatiotemporal scale of this effect would differ among taxa. I measured bee visitation rate and floral resource density over three spatial scales and during four time-periods spanning one season, in 27 agricultural sites across Ontario and Québec, Canada. The present abundance of floral resources at a local scale positively influenced bee visits across all sampling periods. However, differences in the temporal scale of bees’ response to floral resources were observed at landscape scales. Past and present floral resources were positively or negatively associated with bee visits depending on the time of season and which taxon was examined. The number of visits by Andrenidae, honey bees, and bumble bees increased with floral resource abundance in previous time-periods, while other taxa exhibited a negative association with past floral resources, suggesting possible dilution of bee populations at a landscape scale. Understanding the scales at which bee taxa are influenced by floral resources can allow development of land management strategies that could enhance crop pollination and conserve species threatened by agricultural intensification.
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Elbagrmi, Twfeik. "Effects of honeybees on wild pollinators and pollination services in the UK." Thesis, University of Leeds, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595651.
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This thesis addresses various aspects of the role of competition between European honeybees and wild pollinators on pollinator community structure and pollination services. In experimental studies in flight cages, the presence of foraging honeybees led to a decrease in visitation rate of bumblebees and increased their flower handling time. The travelling rime that bumblebees spent flying between flowers showed a positive relationship with number of honeybees per flower. In a field study, the proximity to a honeybee apiary significantly decreased the abundance of different groups of pollinators. Species richness and diversity of wild pol1inators also declined with proximity to the honeybee apiary, except for bumblebees. Pollination service significantly declined with the increase in distance from the apiary. In a field study assessing the development of experimental bumblebee colonies, those located near the honeybee apiary produced fewer queens and smaller queens and males. The offspring sex-ratio was significantly more male-biased in colonies closer to the apiary, which is less costly, but may result in lower fitness depending on the population sex ratio. Average colony weight near the apiary was lower in one of the two years. Finally, in an experimental study of plant pollination success, I found that pollinator performance (in terms of pollen transferring and their contribution to seed set) depended on the plant species, as bumblebees were more efficient on oilseed rape than honeybees and hoverflies while they did not differ from honeybees in terms of field bean pollination and seed set. Together these studies support the idea that honeybees interfere with foraging activity of wild pollinators. For bumblebees, the presence of high density of honeybees can negatively affect colony fitness. For the plant species that I studied, there were clear differences in the quality of visits for pollination between the species. However, this did not lead to lower seed set, because honeybee numbers overcompensated for the lower numbers of wild pollinators
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Henselek, Yuki [Verfasser], Stefan [Akademischer Betreuer] Baumgärtner, and Alexandra-Maria [Akademischer Betreuer] Klein. "The economic insurance value of wild pollinators in almond orchards in California." Freiburg : Universität, 2019. http://d-nb.info/1200851579/34.
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Håkansson, Michaela. "Farming system and landscape complexity affects pollinators and predatory insect communities differently." Thesis, Linköpings universitet, Biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-110051.
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It has been argued that organic farming sustains a higher biodiversity than conventional farming. This might promote the ecosystem services that exist in agricultural landscapes such as pollination and pest control. Here, I examined the effect of farming system (organic vs. conventional) with respect to the time since farming system transition, landscape heterogeneity and plant richness on pollinating and predatory insects. In total, data from 30 farms were used, of which 20 were organic and 10 were conventional. The data were analyzed using general linear models and model averaging. The results show that insect groups responded differently to various factors. Pollinators were more sensitive to landscape complexity, showing an increase of abundance and species richness with an increased heterogeneity. Predators on the other hand reacted to farming system, where there was an increase in abundance and species richness on organic farms.
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Suetsugu, Kenji. "Diverse interactions of heterotrophic plants with their hosts, pollinators and seed dispersers." Kyoto University, 2014. http://hdl.handle.net/2433/192205.
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Kyoto University (京都大学)0048
新制・課程博士
博士(人間・環境学)
甲第18605号
人博第701号
新制||人||167(附属図書館)
26||人博||701(吉田南総合図書館)
31505
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 加藤 眞, 教授 市岡 孝朗, 教授 瀬戸口 浩彰, 教授 宮本 嘉久, 教授 新宮 一成
学位規則第4条第1項該当
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O'/Dea, Justin Kevin. "Greening summer fallow: agronomic and edaphic implications of legumes in dryland wheat agroecosystems." Thesis, Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/odea/ODeaJ1211.pdf.
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Adopting nitrogen (N)-fixing legumes into crop rotations is an accessible, ecological practice capable of increasing agricultural sustainability. Nonetheless, in northern Great Plains (NGP) wheat systems, proper water use management and the realization of N benefits are barriers to legumes replacing summer fallow. Legumes should also be able to mitigate legacies of soil organic matter losses from summer fallow. We conducted a participatory field-scale study in north-central Montana, assessing the viability of no-till, early-terminated legume green manures (LGMs) as summer fallow replacements. Soil water and nitrogen were measured to evaluate LGM effects on subsequent wheat crops. Farmers were interviewed to elucidate perspectives and challenges of adopting LGMs. Compared to fallow, LGMs depressed subsequent wheat yields by 6% (0.24 Mg ha -¹), and lowered grain protein at sites where wheat was fertilized with N (9 g kg -¹); grain protein was increased at unfertilized sites (5 g kg -¹). Absent rotational benefits from LGMs were attributed to dry conditions in the LGM year leading to low LGM biomass N and reduced N mineralization potential in soils, rather than soil water limitation to subsequent wheat. Farmers were curious about possible longterm benefits from LGMs, but expressed that the economic viability of LGMs appeared tenuous in the short-term. We also examined attributes and processes in soils from an eight-year-old rotation study containing fallow-wheat, continuous wheat, and legume-inclusive no-till rotations. We examined potentially mineralizable C and N (PMC and PMN), microbial biomass-C and wet aggregate stability (WAS). Nitrogen fertilizer was also added to a duplicate set of soils, and effects on C and N mineralization were evaluated. Legume-inclusive systems generally had higher levels of soil parameters, and had 26-50% greater PMN than wheat-only systems. Systems returning the most crop residue C to the soils had higher WAS regardless of legumes. Nitrogen additions depressed C and N mineralization. Results of these studies suggest that in NGP agroecosystems, LGMs can avoid limiting soil water available to subsequent wheat when terminated early and managed as no-till crops, but that legumes should be viewed as an investment in soil quality which may precipitate rotational N benefits more reliably after three or more appearances in rotation.
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Maloney, Darlene. "The Ecology of Wolf Spiders (Lydosidae) in Low Bush Bluberry (Vaccinium angustifolium) Agroecosystems." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/MaloneyD2002.pdf.
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Briar, Shabeg Singh. "Nematodes as bioindicators of soil food web health in agroecosystems a critical analysis /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1173284523.
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Gorman, Ashley. "Understanding seed-soil adhesion by myxospermous seeds and their biophysical function in agroecosystems." Thesis, University of Dundee, 2019. https://discovery.dundee.ac.uk/en/studentTheses/33ec7318-88e9-4e39-9a31-c26a8b1a1638.
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Seedbanks provide many ecosystem services that support wildlife and regulate soil function. The fate of arable seeds is vital in shaping the aboveground composition of plant communities in agroecosystems. Understanding seed fate informs seedbank dynamics with multi-species interactions, as well as safeguarding arable biodiversity and food security. While many seed fate pathways are well known, the role of myxospermy in temperate agricultural soils is rarely addressed. Mucilage released by myxospermous seeds can modify the soil physical, hydraulic and microbial environment surrounding the seed. The principle biophysical mechanisms underlying the redistribution of weed seeds in eroded soils are unknown. It is possible that myxospermy delivers crucial services at the field scale, such as soil stability and water retention. However, modifications of the soil physical environment have been investigated using only a single-species approach and are often tested with extracted mucilage rather than seeds in-situ. As multiple taxa produce myxospermous seeds, the effects of a single species cannot be generalised. As seeds co-exist in the soil as multi-species communities, a multi-species approach is needed to further understand the functionality of seed mucilage and their implications for soil, relative to the wider seedbank. This thesis focussed on examining the mechanisms responsible for the adhesive interactions between soil and myxospermous seeds and discusses the ecological function and behaviour at the soil particle scale.
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Hansen, Ashton Anne. "Exploring Effects of Weed Management in Agroecosystems: Arthropods, Soil Properties and Soybean Production." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27538.
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Soil-dwelling arthropods contribute to agroecosystems, but it?s unclear how specific taxa respond to weed management practices. Objectives were to explore 1) response of Collembola to weed management in a glyphosate-tolerant soybean system and 2) impacts of weed management and soil arthropod reduction (via insecticide) on soil and plant parameters. Weed management had variable effects on Collembola, whereas location had a consistent effect on diversity and density. Increased weed pressure decreased soil nitrate and reduced soybean yield. Reduction of soil arthropods didn?t impact soil nitrate or yield, but increased the number of soybean root nodules. This could be due to decreased root herbivores, or overcompensation of the plant. Previous research emphasized effects of plant communities on soil arthropods, but our study suggests soil properties strongly influence arthropod communities. Although this study does not show obvious benefits of soil arthropods, long term insecticide application may be detrimental to crop production.
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Sugihara, So. "Soil Microbial Dynamics in Tropical Agroecosystems under Different Land Managements and Soil Textures." Kyoto University, 2010. http://hdl.handle.net/2433/120471.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第15428号
農博第1813号
新制||農||979(附属図書館)
学位論文||H22||N4527(農学部図書室)
27906
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 舟川 晋也, 教授 縄田 栄治, 教授 間藤 徹
学位規則第4条第1項該当
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Smithson, Ann. "Frequency-dependent selection amongst floral variants through the foraging behaviour of bumblebees, Bombus terrestris." Thesis, University of Exeter, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296288.
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Ghana, Salah. "Experimental studies of hybridization in fig trees (Ficus spp., Moraceae) and their pollinators." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582116.
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Fig trees and their specific pollinators have an obligate mutualistic relationship where both depend on each other to complete their life cycles. Each fig species is pollinated by one or more specific pollinators with host specificity maintained by physical and chemical barriers. Many mistakes however, have been recorded where pollinators enter atypical hosts and manage to pollinate them and produce hybrids. This thesis focuses on the fitness of experimentally generated hybrid fig trees and the ability of fig wasps to reproduce inside these hybrids. The dioecious fig tree F. montana and its pollinator Kradibia tentacularis from Indonesia and F. asperifolia from Uganda and their hybrids were used. Styles of female flowers in male and female figs lengthened at similar times during development and style lengths from female figs were always longer. In receptive phase figs, the ovipositor of K. tentacularis was able to reach all styles in male figs and some styles from female figs of hybrids and their parents. Using a new technique for staining fig wasps eggs, K. tentacularis was shown to lay one or two eggs in F. asperifolia, FI and backcross male figs, but failed to reproduce in F. asperifolia and FI s. In backcrosses, it could reproduce in figs of a few plants but not in the rest. It was inability to gall rather than inability to oviposit that prevented pollinator reproduction. FI seeds germinated and these seedlings grew as well as their parents, but later on most FIs died or were dwarfed. Backcrosses and other hybrid crosses showed better performance than FIs. Male FI s were sterile and hybrid fitness was lower than that of their parents, but FI female plants were able to produce fertile seeds when pollinated by F. montana, so introgression was possible.