Dissertations / Theses on the topic 'Agroecosystem'

Current interest in cover cropping is focused on enhancing ecosystem services beyond soil conservation. Cover crop (CC) species function uniquely in their effects on ecosystem services when grown in monoculture or mixtures. This research integrated field experiments and a literature synthesis to evaluate the role of cover crops in improving nitrogen (N) management and simultaneously providing multiple ecosystem services. Legume CC fertilized with poultry litter (PL) could replace 101 to 117 kg N ha-1 of fertilizer in corn (Zea mays L.) production. Rye (Secale cereale L.) CC fertilized with PL had a negligible effect on corn production. Biculture fertilizer equivalence ranged between -12 to +75 kg N ha-1. Fertilizer equivalence of legume-containing treatments increased across time. Without CC, fall-applied PL failed to supply N to corn. Ecosystem services of CC and PL illustrate complex species functions. Bicultures produced more total biomass than monocultures in year 1 but less than rye in year 2. Bicultures were as effective in suppressing weeds as rye, produced corn yield similar to legume, and by the second year had similar amounts of available soil N as the legume. Poultry litter effects and interspecific effects cover crop species biomass differed. Rye yield increased, while legume yield decreased slightly in biculture. Poultry litter increased legume N content and a decrease in legume C:N, while rye N content and C:N were unaffected. The synthesis corroborates that mixed and biculture cover crops yield more than the individual component species. Overyielding was transgressive in 60% of cases studied. Mixture effects varied by species: rye and brassica yield increased, while legume decreased in mixtures. The effect of mixed CC on crop yields varied by crop species and management practices, though generally crops increased 8 to 18% overall. This work can be applied to the design of complex CC and PL systems that optimize individual species functions to enhance ecosystem services.
Ph. D.

If upland rice production is to be sustained on sloping land, soil erosion and fertility decline must be addressed. Where soil profiles are deep, hedgerows of Gliricidia sepium and Cassia spectabilis, planted on the contour, reduce soil erosion by promoting terrace formation and overcome fertility depletion by providing nutrient rich biomass. G. sepium and C. spectabilis established by seed survived better than by cuttings. Although increased hedgerow biomass was initially obtained when both species were intercropped, intense competition was observed in established hedgerows. Consequently, mixing both species at high planting density is not recommended as C. spectabilis, a non-fixing legume, may deplete soil-N reserves. In acid soils, biomass production of G. sepium was significantly increased when lime (6 t/ha) was applied. On 18 to 30% slopes, upland rice and maize production improved along fertility and moisture gradients. Rice yields were increased when biomass of G. sepium was incorporated into the soil, up to an optimum level equivalent to 40 kg N/ha. Mulching C. spectabilis increased maize productivity during the drought prone second season. Competition was observed at the hedgerow-crop interface particularly at the upper one as a result of terracing. Although green manuring increased crop yield, broadleaf weeds, seedling maggot, stemborer and blast also increased. Strategies to manage hedgerow biomass that minimize these problems need to be developed.

Our earth is currently undergoing unprecedented human induced climate change, which is expected to drive widespread changes in species distributions and abundances that will affect natural pest suppression. Recent studies have suggested that climate change may cause changes to predator and herbivore assemblages in ways that alter multi-trophic food webs and affect the stability of ecosystems. Moreover, higher temperatures and increased climatic variability are expected to induce differential responses from predators and their prey that will undoubtedly disrupt species interactions. This thesis aims to test how climate change will impact the ability of natural enemies to continue to control pests in agroecosystems, and how they will continue to survive and function. In a field experiment using 13 farm sites across a natural temperature gradient, I found that temperature had direct positive effects on the abundances of the dominant parasitoid (an aphid specialist) and hyperparasitoid species, highlighting the importance of specific species responses in shaping larger communities. I also found that overall community composition was affected by temperature, with composition in warmer sites changing more throughout the season than cooler sites. In a future of inevitable climatic changes this result tells us we can expect arthropod community structure to change, which will have questionable impacts on overall population dynamics. To build on the field experiments, I used laboratory experiments to test differential responses of species to both drought and temperature and found that natural enemies responded to drought and temperature in a non-additive way, suggesting that the interaction between various climate change drivers is more important than their singular effect. Also, different species of natural enemies responded differently to abiotic factors, highlighting the importance of conserving natural enemies that can maintain important functional attributes in the face of climate change. Although biodiversity can be important for ensuring ecosystem functioning, response diversity, rather than species richness, may better promote ecosystem resilience, especially in the face of changing climate. The mechanisms underlying biodiversity effects are often difficult to disentangle, however, by manipulating the diversity of climate responses exhibited by ecosystem service providers, I tested how the rates and stability of prey suppression by predators are affected by climate warming and drought. I found that predator combinations with different individual responses to climate change maintained greater and less variable (i.e. more stable) prey suppression, compared with single predator species or combinations of predators with similar climate responses. This response complementarity became strongest through time and under drought or high temperature treatments. I suggest that response complementarity provides ‘insurance’ effects, which may be more important than previously envisaged for maintaining ecosystem functions such as biological control under global environmental change. Overall, the non-additive effects of different climate drivers, combined with differing responses across trophic levels, suggests that predicting future pest outbreaks will be more challenging than previously imagined.

The present work investigated the biodiversity of soil fungi of agricultural areas differently managed by means of new generation sequencing technologies – NGS. The main object of this research was the analysis of the fungal biota in the Colombian soils, especially that of the upper Andean agro-environment. The study area was located in the region of Boyacá between 2800 and 3200 m asl. and characterized by different form of soil appropriation (apple and peach orchards, 10-year-old wood, and uncultivated grass field). Moreover, a case study has been analysed in Italy where metagenomic of soil micobiota was pictured in a production farm, in three plots differently managed in terms of fertilization, pesticide and tillage application: conventional, organic, no-tillage. Chapter I represents the general introduction of the thesis. Chapter II focuses on the practices of soil appropriation in the indigenous and urban Colombian contexts, both from biologically and socio-culturally point of view. The southern region of Colombian Amazon was taken into consideration, since this region constitutes an important model for the traditional utilization of natural resources and a fundamental basis for the definition of strategies for ecosystem management. In Chapter III the focus is on the mycological knowledge of Colombian soils based on data published in scientific research papers. Published data on diversity of native soil microfungi reported for the different natural regions of Colombia were analysed and compared. Some of the most relevant aspects of the country's mycological diversity are discussed and the most frequently registered species and genera, as well as the references for each of them, are presented. In Chapter IV the soil mycobiota in the Colombian High-Andean agro-environment is assessed through high-throughput sequencing technology. The chapter depicts the entire soil fungal community from qualitative and quantitative point of view in areas with different land use. The bootstrap-based clustering analysis highlighted that different land use strongly influences the soil mycobiota: the uncultivated and cultivated areas are characterized by abundant presence of some exclusive species. Differences in fungal species composition is consistent with the clustering analysis on higher taxonomic hierarchical level composition. Chapter V reports data collected in a case study planned in the Italian agro-environment context. The results showed that various agricultural management practices and seasonality influence the composition of the soil mycological community in agroecosystems, through a metagenomic picture. Metagenomic analyses show that the highest richness indices correspond to soils under organic production systems, while the non-tillage system showed the most divergent communities, with their own composition, prevalence and seasonal trends. Finally, the Chapter VI represents a sort of perspective for those areas subjected to conventional management and strongly polluted by pesticides that could be remediated and led towards a sustainable agriculture. The usefulness of soil fungi as key tools for the sustainable bioremediation of chemical pesticides in the soil is discussed as a strategy for the recovery of the quality of degraded agricultural soils. The results of this study provide insight into the complexity of micobiota of managed soils under different farming systems, with the ultimate goal of better understanding the multiple mechanisms governing soil quality and to develop an environmentally sound management that improves production, allowing the maintenance of ecosystem diversity and the wellness of human communities linked.

To analyse the influence of crop rotations with a different ratio of nitrogen-fixing crops, catch crops and fertilisation with organic fertilisers on the following: 1. Soil enzyme activity; 2. Agrochemical properties of the soil and nitrogen balance; 3. Weed response; 4. Weed seed bank in the soil; 5. Crop yield and productivity.
Agroekosistemų optimizavimo augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje tyrimai vykdyti 2004–2009 m., Lietuvos žemės ūkio universiteto Bandymų stotyje, sertifikuotame ekologinės žemdirbystės lauke, karbonatingame sekliai glėjiškame išplautžemyje (IDg8-k) – Calcari-Epihypogleyic Luvisol (LVg-p-w-cc). Tyrimų hipotezė. Optimizuoti agroekosistemas ekologinėje žemdirbystėje galima taikant priemonių kompleksą: parenkant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius bei tręšiant organinėmis trąšomis. Tyrimų tikslas – įvertinti agroekosistemų optimizavimo galimybes ekologinėje žemdirbystėje derinant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius ir tręšiant organinėmis trąšomis. Tyrimų uždaviniai: Ištirti sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių ir tręšimo organinėmis trąšomis įtaką: 1. dirvožemio fermentų aktyvumui; 2. dirvožemio agrocheminėms savybėms ir azoto balansui; 3. pasėlių piktžolėtumui; 4. dirvožemio armens užteršimui piktžolių sėklomis; 5. augalų derlingumui ir bendrosios energijos kiekiui. Mokslinio darbo naujumas. Ekologinės žemdirbystės sąlygomis kompleksiškai įvertintas sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių bei tręšimo organinėmis trąšomis poveikis agroekosistemoms. Tai suteikia naujų žinių apie potencialaus dirvožemio derlingumo palaikymo, pasėlių ir dirvos piktžolėtumo kontrolės... [toliau žr. visą tekstą]

Alfalfa Trap Cropping Increases Abundance Of Key Arachnids In An Organic Strawberry Agroecosystem Eighty three percent of the strawberries consumed in North America are grown in California, where the widespread use of insecticides has become hazardous to public health. The intensive use of pesticides for growing strawberries causes serious health risks to farm workers, in addition to contaminating the soil and groundwater. The cost to the environment and public health in the United States is estimated at $12 billion annually. Finding effective nontoxic management strategies for insect pests has become essential for long term sustainability. One strategy strawberry producers can use to promote sustainability is to increase the effectiveness of biological control techniques. Field experiments in other crops suggest that arachnid diversity and abundance may provide such a role in controlling insect pests and that agroecosystem diversification can enhance arachnid populations. This study therefore evaluated the composition, abundance, and pest control potential of arachnid communities in an organic strawberry field in California. The study found that by integrating alfalfa trap crops into organic strawberries, arachnid populations were substantially increased. Results reflected substantial increases in both male and female arachnid populations in and near alfalfa strip crops, with spider and harvestman arachnid families increasing most dramatically. Preliminary data suggest that an increase in alfalfa trap crops may lead to a reduction of the primary strawberry insect pest, Lygus hesperus, which is consumed by arachnids. These results provide useful new information for California farmers.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19044号
農博第2122号
新制||農||1032(附属図書館)
学位論文||H27||N4926(農学部図書室)
31995
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 縄田 栄治, 教授 舟川 晋也, 教授 白岩 立彦
学位規則第4条第1項該当

A survey study was undertaken to identify the plant viruses, to document the occurrence of virus diseases, and to document the seasonal population dynamics of insect vectors in a semi-isolated agricultural site in Central Arizona. A typical year-round cropping history at the site consists of cotton and seasonal sequences of vegetables. The most abundant insects caught using 24-hr exposures of yellow sticky traps were whiteflies (Trialeurodes abutilonea Haldeman and Bemisia tabaci Genn.) and the cotton (or melon) aphid (Aphis gossypii Glover). Of the three, only B. tabaci and A. gossvpii are recognized as virus vectors in Arizona. The most prevalent plant virus identified in vegetable crops and/or weeds was lettuce infectious yellows virus (LIYV), a whitefly-transmitted virus. The virus was detected in lettuce, (greenleaf, romaine, iceberg, red leaf) watermelon, cantaloupe, spinach, and cilantro. In addition, the watermelon curly mottle/squash leaf curl virus complex (WCMoV-SLCV), watermelon mosaic virus 2 (WMV-2) zucchini yellow mosaic virus (ZYMV), cucumber mosaic virus (CMV), and squash mosaic virus (SqMV) were identified in cucurbits at various times and locations throughout the season.

Les aportacions de nitrogen reactiu (N) mitjançant el procés Haber-Bosch (fixació industrial de N2 per produir fertilitzants) i el cultiu de lleguminoses són responsables de més de la meitat de l’aportació de N als ecosistemes terrestres. Aquests inputs excessius provinents dels agroecosistemes han augmentat els fluxos d’òxid nitrós (N2O), amoníac (NH3) i nitrat (NO3−), provocant efectes tals com l’acceleració de l’escalfament global, l’eutrofització i la reducció de l’ozó estratosfèric, entre d’altres. L’esmena del sòl amb biochar, el sòlid ric en carboni (C) produït per la conversió termoquímica de biomassa en condicions limitants d’oxigen, podria ser una eina valuosa per fer front als fluxos elevats de N. No obstant, la implementació a gran escala de biochar es veu compromesa per les incerteses sobre possibles conseqüències adverses, així com pels seus efectes a llarg termini sobre la qualitat del sòl, atesa la seva persistència al sòl. Per tal d’escurçar aquests buits de coneixement, es va avaluar en condicions d’hivernacle (Capítol 1) i en condicions de camp (Capítol 2) un biochar de gasificació que va demostrar prèviament poder reduir el nivell de NO3− soluble al sòl. El Capítol 1 examinà la possible mitigació de la lixiviació de nitrats tant a curt com a llarg termini i a dues dosis d’aplicació contrastades (12 i 50 t ha-1). Es van examinar columnes de sòl amb biochar fresc i biochar envellit 6 anys al camp. Al cap de 8 mesos, es va trobar una reducció significativa de NO3− en la solució del sòl, així com d’altres ions (incloent clorur, magnesi, sodi i calci), per a les dues dosis d’aplicació de biochar fresc. Aquest fenòmen s’atribuí a la formació d’un recobriment organo-mineral sobre els porus del biochar, tot atrapant aigua i nutrients dins els porus del biochar. Tot i la disminució de NO3− en la solució del sòl, la lixiviació no va veure’s afectada pel biochar, posant en dubte la seva capacitat de mitigació. Al Capítol 2, s’avaluà la qualitat del sòl mitjançant el seguiment de diverses propietats del sòl en mesocosmos de camp establerts fa 6 anys (d’on provenen les mescles sòl-biochar envellit utilitzats al Capítol 1). La dosi de 50 t ha-1 fou la més eficaç en el segrest de C i va millorar el contingut d’humitat al sòl puntualment. No obstant, aquesta dosi representà un trade-off ja que va impactar negativament les comunitats de fauna del sòl (nematodes i col·lèmbols), i també va augmentar les emissions de metà (CH4). Encara que la dosi de 12 t ha-1 no presentà aquests efectes negatius, va mostrar indicis de metabolisme de compostos recalcitrants de C, que, si es mantingués en el temps, podria afectar el potencial de segrest de C del biochar. En conjunt, es pot concloure que al nostre agroecosistema la dosi de 12 t ha-1 representa un escenari amb menys riscos. Finalment, el Capítol 3 va abordar els possibles beneficis agronòmics d’incloure un biochar de piròlisi lenta en tres formulacions de fertilitzants organo-minerals (NPK, NP i K). La lixiviació de nutrients es va alentir en la formulació amb biochar i NPK (NPK + B). Probablement, el C làbil incorporat amb el biochar i l’input simultani de diversos nutrients podria haver estimulat el creixement microbià causant un emmagatzematge temporal de nutrients a la biomassa microbiana. Tot i que el fertilitzant NPK + B només va millorar significativament la biomassa de palla d’ordi i no el gra, tots els fertilitzants formulats amb biochar van provocar un millor estat nutricional vegetal ( en relació al potassi, sofre, calci i manganès). Aquests resultats indiquen que les formulacions investigades són prometedores per al desenvolupament de fertilitzants de nova generació.
Las aportaciones de nitrógeno reactivo (N) mediante el proceso Haber-Bosch (fijación industrial de N2 para producir fertilizantes) y el cultivo de leguminosas son responsables de más de la mitad del input de N a los ecosistemas terrestres. Estos insumos excesivos provenientes de los agroecosistemas han aumentado los flujos de óxido nitroso (N2O), amoníaco (NH3) y nitrato (NO3-), provocando efectos tales como la aceleración del calentamiento global, la eutrofización y la reducción de la ozono estratosférico, entre otros. La enmienda del suelo con biochar, el sólido rico en carbono (C) producido por la conversión termoquímica de biomasa en condiciones limitantes de oxígeno, podría ser una herramienta valiosa para hacer frente a los flujos elevados de N. Sin embargo, la implementación a gran escala del biochar se ve comprometida por la incertidumbre sobre posibles efectos adversos, así como por sus efectos a largo plazo sobre la calidad del suelo, debido a su persistencia en el suelo. Para reducir estas brechas de conocimiento, se evaluó en condiciones de invernadero (Capítulo 1) y en condiciones de campo (Capítulo 2) un biochar de gasificación que demostró previamente poder reducir el nivel de NO3- soluble del suelo. El Capítulo 1 examinó la posible mitigación de lixiviación de nitratos a corto y largo plazo en dos dosis de aplicación contrastadas (12 y 50 t ha-1). Se examinaron columnas de suelo con biochar fresco y biochar envejecido durante 6 años en el campo. Al cabo de 8 meses, se encontró una reducción significativa de NO3- en la solución del suelo, así como de otros iones (incluyendo cloruro, magnesio, sodio y calcio), para las dos dosis de aplicación de biochar fresco. Este fenómeno se atribuyó a la formación de un recubrimiento organo-mineral sobre los poros del biochar, que atraparía agua y nutrientes dentro de los poros del biochar. A pesar de la disminución de NO3- en la solución del suelo, la lixiviación no se redujo, poniendo en duda la capacidad de mitigación del biochar. En el Capítulo 2, se evaluó la calidad del suelo mediante el seguimiento de varias propiedades del suelo en mesocosmos de campo establecidos hace 6 años (de donde provienen las mezclas suelo-biochar envejecido utilizados en el Capítulo 1). La dosis de 50 t ha-1 fue la más eficaz en el secuestro de C y mejoró el contenido de humedad en el suelo puntualmente. Sin embargo, esta dosis representó un trade-off, ya que impactó negativamente las comunidades de fauna del suelo (nematodos y colémbolos), y también aumentó las emisiones de metano (CH4). Aunque la dosis de 12 t ha-1 no presentó estos efectos negativos, mostró indicios de metabolismo de compuestos recalcitrantes de C, que, si se mantuviera en el tiempo, podría afectar el potencial de secuestro de C del biochar. En conjunto, se puede concluir que en nuestro agroecosistema la dosis de 12 t ha-1 representa un escenario con menos riesgos. Finalmente, el Capítulo 3 abordó los posibles beneficios agronómicos incluir un biochar de pirólisis lenta en tres formulaciones de fertilizantes organo-minerales (NPK, NP y K). La lixiviación de nutrientes se ralentizó en la formulación con biochar y NPK (NPK + B). Probablemente, el C lábil incorporado con el biochar y el input simultáneo de varios nutrientes podría haber estimulado el crecimiento microbiano causando un almacenamiento temporal de nutrientes en la biomasa microbiana. Aunque el fertilizante NPK + B solo mejoró significativamente la biomasa de paja de cebada y no el grano, todos los fertilizantes formulados con biochar provocaron un mejor estado nutricional vegetal (en relación al potasio, azufre, calcio y manganeso). Estos resultados indican que las formulaciones investigadas son prometedoras para el desarrollo de fertilizantes de nueva generación.
Anthropogenic inputs of reactive nitrogen (N) via the Haber-Bosch process (synthetic N2 fixation for fertiliser production) and legume cultivation are responsible for over half of the input of N to terrestrial ecosystems. These excessive inputs from agroecosystems have resulted in enhanced fluxes of nitrous oxide (N2O), ammonia (NH3), and nitrate (NO3−), which induce far-reaching adverse effects, including the acceleration of global warming, promoting eutrophication, and depleting stratospheric ozone, among others. Soil-application of biochar, the carbon(C)-rich solid produced by thermochemical conversion of biomass under oxygen-limited conditions, could be a valuable tool to cope with elevated N fluxes. However, broad-scale biochar implementation is hindered by the uncertainties concerning possible unintended consequences as well as its long-term effects on soil quality, given its persistence in soil. In order to fill in some of these knowledge gaps, a pine gasification biochar that was found to reduce nitrate contents in soil solution in a previous study was assessed both under greenhouse conditions (Chapter 1) and under field conditions (Chapter 2). Chapter 1 was aimed at evaluating whether this particular biochar could induce a nitrate leaching mitigation response both in the short and long-term and at two contrasted application rates (12 and 50 t ha-1). To do so, soil columns filled with either fresh biochar or 6-yr field-aged biochar were monitored for 8 months. At the end of the trial, a significant reduction of NO3− in soil solution as well as other ions (including chloride, magnesium, sodium, and calcium) was found for both application rates in the fresh biochar-amended columns but not in the aged biochar scenario. The formation of an organo-mineral coating that entrapped nutrient-enriched water into biochar pores was ascribed as the most plausible explanation. Despite the alleviation of NO3− in soil solution, its leaching was unaffected by biochar treatment, casting doubt about possible environmental effects. In Chapter 2, by monitoring a wide range of soil properties in 6-yr old field mesocosms (from where the soil-aged biochar mixtures of Chapter 1 were taken), a soil quality assessment was conducted. The 50 t ha-1 application rate was the most effective in sequestering C and presented enhanced water contents at some sampling dates. However, an important trade-off emerged, since it exerted negative effects towards soil fauna communities (nematodes and collembolans), and also it boosted methane (CH4) soil emissions. Conversely, the 12 t ha-1 rate did not pose serious risks to soil faunal communities and soils acted as a CH4 sink. On the other hand, this same treatment showed signs of promotion of recalcitrant carbon metabolism, which, if maintained over time, could affect biochar’s C sequestration potential and reduce its expected persistence. Taking all into consideration, in our agroecosystem, the 12 t ha-1 rate would be safer to apply. Finally, Chapter 3 addressed the potential agronomical benefits of including biochar into fertiliser formulation. Particularly, a slow pyrolysis biochar was included in three organo-mineral fertiliser formulations (NPK, NP, and K). Nutrient leaching was slowed down in the formulation combining biochar and NPK (NPK+B). This effect was plausibly attributed to the labile-C added with the slow-pyrolysis biochar and the concomitant provision of NPK, which could have promoted microbial growth and caused a temporary storage of nutrients in microbial biomass. While the NPK+B fertiliser only significantly enhanced barley straw biomass and not grain, all biochar-based fertilisers presented improved plant nutrient content and export (regarding potassium, sulphur, calcium, and manganese). Both the improved nutrient release pattern in NPK+B and the enhanced crop nutrient status found for all biochar-based fertilisers indicate that the investigated formulations hold promise for further research and development of new generation fertilisers.
Universitat Autònoma de Barcelona. Programa de Doctorat en Ecologia Terrestre

The potential control of cucumber beetles, Acalymma vittatum (Fab.) and Diabrotica undecimpunctata howardi (Barber)(both Coleoptera: Chrysomelidae) two major pests of cucurbits, was assessed in a cucurbit agroecosystem by using buckwheat (Fagopyrum esculentum Moench) border habitat to attract the natural enemies, Celatoria diabroticae (Shimer) and Celatoria setosa (Coquillett) (both Diptera: Tachinidae) and Chauliognathus pennsylvanicus (Deg.) (Coleoptera: Cantharidae). Five different plants were seeded in the border and buckwheat dominated. Four natural enemy groups were also included as indicators of the attractiveness of the floral border: The Order Diptera; the Families Tachinidae and Syrphidae of Diptera; and the Order Hymenoptera. In 1995-1996, rows of squash, Cucurbita pepo (L.) var. melopepo (Alef.) ‘Seneca Prolific’, and cucumbers, Cucumis sativa (L.) ‘Arkansas Littleleaf’, were planted perpendicular to floral border habitats. Sticky traps and modified Malaise traps on transects at intervals from the border were used to monitor insect numbers. Insect counts and yields of cucurbits were analyzed using analysis of variance with contrasts for linear and quadratic effects and regression model fitting. Borders were strongly attractive to Diptera and moderately attractive to C. pennsylvanicus, Syrphidae, Tachinidae, and Hymenoptera. C. setosa and C. diabroticae counts were too low to analyze and borders habitats did not have any meaningful effect on yields. The border conserved populations of Diptera, leatherwings, Hymenoptera, and tachinids on some dates and may be useful with economic thresholds for pest management because of an observed gradient of insect movement.
Master of Science

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.

Thesis (M.S.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed July 16, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (leaves 37-39).

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Family agriculture, object of this study, still follows the traditional pattern of cultivation, occurring even in a town close to Manaus, capital of the state, and although there is a close relationship with the consumer market, located in the town of Itacoatiara. To arrive at these results, the research used the case study method, with a systemic and holistic approach, based on Morin, because it allows the research has a critical view of reality and the deep study of multiple cases of family farming in the Amazon presents. Farmers in the community of São João do Araçá not suffer great hegemonic influence of the capitalist system of agribusiness in relation to land use and management of natural resources. Harvest is practiced sustainably, hunting, fishing, harvesting of plant resources extractive, such as firewood and for house construction, medicines and food are removed only enough for family use. Agriculture is still held priority to meet the basic needs of the family unit, being sold only the surplus. This form of land use permits regeneration of resources, especially land, is still used as a "resting", ie the rest of the soil to recover its fertility. The presence of mature poultry is an indicator of this type of management because it proves that the land use is not intensive and which are small areas used for agriculture. The workmanship is basically family and social relations of work as task force, partnership and half remain strong both in collective activities related to the community and in their agricultural activities in their agroecosystems. To arrive at these results, the research used the case study method, with a systemic and holistic approach, based on Morin, because it allows the research has a critical view of reality based on the study of the complexity of multiple instances of that family Amazon has.
A agricultura familiar, objeto deste estudo, ainda segue o sistema tradicional de cultivo, mesmo ocorrendo em uma localidade próxima a Manaus, capital do Estado, e ainda que haja uma relação estreita com o mercado de consumo, localizado na sede do município de Itacoatiara. Os agricultores da comunidade São João do Araçá compõem uma população de resistência à influência do sistema capitalista hegemônico do agronegócio no que se refere ao uso da terra e ao manejo de seus recursos naturais. O extrativismo é praticado de forma a atender somente às suas necessidades básicas; a caça, a pesca, a coleta dos recursos vegetais extrativistas, como madeira para lenha e para construção de casas, os remédios e os alimentos são retirados em quantidade suficiente para uso da família em primeiro lugar, e uma pequena parte de alguns produtos são comercializados. A agricultura ainda é realizada com vistas a atender prioritariamente à família na unidade familiar, sendo comercializado apenas o excedente. Essa forma de uso da terra permite a regeneração dos recursos, especialmente do solo, visto que é utilizado o “pousio”, ou seja, o descanso do solo para recuperar sua fertilidade. A presença de capoeira madura é um indicador desse tipo de manejo, pois comprova que o uso do solo não é intensivo e que são utilizadas pequenas áreas para agricultura. A mão-de-obra é basicamente familiar, e as relações sociais de trabalho como- mutirão, parceria e a meia permanecem fortes tanto nas atividades coletivas relacionados à comunidade quanto em suas atividades agrícolas em seus agroecossistemas. Para chegar a esses resultados, a pesquisa utilizou o método Estudo de caso, com uma abordagem sistêmica e holística, baseada em Morin, pois permite que a pesquisa tenha uma visão crítica da realidade baseada no estudo da complexidade dos múltiplos casos que a agricultura familiar da Amazônia apresenta.

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This work is part of a larger research project called "Studies Network Systems and Research in Sustainability Indicators for Agroecosystems Based Practices in Family Farming and Agriculture Based on the Principles of Green Revolution in Northeast Brazil" and deals with the adaptation and application of MESMIS model - Marco Evaluation Systems Natural Resources Management Incorporating Sustainability Indicators (1995), in the municipality of Pedras de Fogo, south coast of Paraiba, in order to assess the sustainability index in cassava production, based on agriculture family, as social actors. We know that sustainable development appears as a new concept in processing, generating discussion on the basis of little progress in practical terms. From this perspective, instruments have been created in order to change this reality. It is believed that the indicators are methods that help evaluate and communicate the processes present. The MESMIS, model evaluation indicator facing rural contexts, has been understood as an alternative to overcome the barrier merely theoretical and classificatory, pointing to different parts of a management system. From this perspective, the method was applied transversely into six family units, three basic traditional and three alternative basis, the settlement New Dawn in Pedras de Fogo. Were created in a participatory nine indicators of sustainability compounds (Water Resources, Soil Quality, Management, Diversity, Work and their relations, Participation, Self-Management, Economic Situation, Change and Innovation), quantified from primary data collected through interviews, questionnaires and field observations, which enabled detailing the agroecosystems, determine critical points and noted that although culture is a flexible alternative agricultural practices, traditional management techniques are used frequently, due mainly to the lack of knowledge agroecological . Still, the group of agroecosystems based on alternative crop production, presented best feature, from the point of view of sustainability, in social, economic and environmental, as compared to the group of agroecosystems based on conventional production.
Este trabalho faz parte de uma pesquisa maior, denominado Rede de Estudos e Pesquisas em Sistemas de Indicadores de Sustentabilidade para Agroecossistemas Baseados em Práticas de Agricultura Familiar e da Agricultura Baseadas nos Princípios da Revolução Verde no Nordeste Brasileiro e trata da primeira adaptação e aplicação do modelo MESMIS Marco para Avaliação de Sistemas de Manejo de Recursos Naturais Incorporando Indicadores de Sustentabilidade (1995), no estado da Paraíba. O método foi aplicado no município de Pedras de Fogo, litoral sul do estado, com o objetivo de avaliar o índice de sustentabilidade na produção de mandioca, baseada na agricultura familiar, a partir da percepção dos atores sociais. Sabe-se que o desenvolvimento sustentável aparece como um conceito novo, em transformação, gerando discussões em função dos poucos avanços em termos práticos. Nessa perspectiva, instrumentos vêm sendo criados com objetivo de modificar essa realidade. Entre esses instrumentos estão os indicadores, metodologias que ajudam a avaliar e a comunicar os processos presentes. O MESMIS, modelo de indicador voltado para avaliação de contextos rurais, tem sido compreendido como uma alternativa para ultrapassar a barreira meramente teórica e classificatória, apontando os diferentes pontos de um sistema de manejo. Nessa perspectiva, o método foi aplicado de forma transversal em seis unidades familiares, três de base tradicional e três de base alternativa, no assentamento Nova Aurora, em Pedras de Fogo (PB). De forma participativa foram selecionados nove indicadores de sustentabilidade compostos (Recursos Hídricos, Qualidade do Solo, Manejo, Diversidade, Trabalho e suas Relações, Participação, Autogestão, Situação Econômica, Mudança e Inovação), quantificados a partir de dados primários, coletados por meio de questionário e observações, que permitiram detalhar os agroecossistemas, determinar seus pontos críticos e observar que embora a cultura seja flexível a práticas agrícolas alternativas; técnicas de manejo tradicionais são usadas com frequência, em decorrência, principalmente, da frágil participação dos agricultores, e do baixo nível de conhecimento agroecológico. Ainda assim, o grupo dos agroecossistemas baseado na produção alternativa da cultura, apresentou melhores característica, do ponto de vista da sustentabilidade, nas dimensões social, econômica e ambiental, se comparada ao grupo dos agroecossistemas baseado na produção convencional.

Este trabalho objetivou pesquisar a relação da temperatura de superfície (LST) e do estoque de carbono no solo (ECS) com os diferentes tipos de uso e cobertura do solo (UCT). Sabe-se que tais parâmetros podem ser influenciados pelas atividades antrópicas, podendo afetar a integridade do agroecossistema (IAG) da bacia do Rio Corumbataí (BRC). Entende-se por IAG, a capacidade de manutenção de suas propriedades \"primitivas\" e prestação de serviços ecossistêmicos à sociedade. Para alcançar o objetivo proposto, a dinâmica de UCT foi mapeada, a partir da classificação de imagens do satélite Landsat e fotografias aéreas, dos anos de 1962 a 2011. A LST foi obtida por técnicas de sensoriamento remoto, utilizando a banda termal do sensor TM (Thematic Mapper) do Landsat, para os anos de 1985, 1990, 1995, 1999, 2002 e 2011. A análise do ECS foi feita a partir da coleta de amostras de solo, em diferentes UCT: mata nativa, cana-de-açúcar, pastagem e fruticultura, na profundidade de 0-10 e 10-20 cm. Os resultados indicaram que a LST e os ECS da área de estudo são influenciados pelo UCT e pelo manejo das culturas. Verificou-se ainda que algumas políticas agrícolas, adotadas no período de 1962 a 2011, influenciaram a dinâmica de UCT e, consequentemente, a capacidade do agroecossistema da BRC no fornecimento de serviços ecossistêmicos e também geraram custos ambientais. A abordagem interdisciplinar adotada neste trabalho, com o emprego das geotecnologias, mostrou ser capaz de avaliar a integridade do agroecossistema da BRC, podendo subsidiar o planejamento de uso do solo visando a maximizar a relação benefício/custo das atividades antrópicas, considerando a LST e o ECS. Tal abordagem pode ser aplicada em diferentes áreas do conhecimento para a análise da sustentabilidade e integridade ambiental dos agroecossistemas.
In this work, the aim was search the relationship between both surface temperature (LST) and soil organic carbon (SOC) with several sort of land use cover (LUC). We know such a parameters can be influenced by anthropic activities, it can affects the Corumbataí River basin (CRB) agro ecosystem integrity (AGI). AGI means, the capacity of both maintenance of its \"primitive\" properties and supplies public ecosystem service. Reaching the proposed goal, the LUC dynamic was mapping through both Landsat-TM image classification and aerial photography from 1962 to 2011. The LST has been obtained by remote sensing technique through Lansat-TM thermal band to the years 1985, 1990, 1995, 1999, 2002 and 2011. The ECS analyze was carried out by soil sample collected in different type of LUC: forest native, sugar cane, pasture and orchard, in the 0-10 and 10-20 cm depths. The results have indicated both the BRC of the LST and SOC are influenced by both together LUC and crop tillage. Furthermore, some agricultural policy adopted during from 1962 to 2011 influenced the LUC dynamic, thus the CRB agro ecosystem capacity of supply agro ecosystem services as well as provided environmental cost. The interdisciplinary approach employed, with the use of geotechnologies, has shown to be able to assessment the CRB agro ecosystem integrity, it can supports the LUC planning in order to maximize the benefit/cost ratio anthropic activities, considering both the LST and ECS. Such an approach can be applied in several knowledge areas to evaluation of sustainability and agro ecosystem environmental integrity.

El balanç entre l´entrada de C (dels residus vegetals) i sortides de C (principalment com CO2 de la descomposició del carboni orgànic del sòl -SOC-), determina el contingut de SOC, que és el depòsit de C més voluminós a la superfície terrestre. Als agroecosistemes semiàrids Mediterránis, l’aigua és el principal factor limitant del creixement del cultiu i de l´entrada de residus al sòl. Les pràctiques agronòmiques alternatives poden millorar el creixement vegetal i augmentar la quantitat de residus (entrada de C) en aquestos sistemes. No obstant això la resposta del contingut de SOC dependrà del balanç de les entrades amb les sortides de C. Aquest treball estudia els efectes de l’adopció a llarg termini de sistemes de conreu (NT, sembra directa; MT, mínim conreu CT, conreu convencional) i del nivell de fertilizació nitrogenada (zero; mitjà, 60 kg N ha-1; alt, 120 kg N ha-1) al balanç de C del sòl i el contingut de SOC. El contingut de SOC augmentà finalment 4.3 i 3.9 Mg C ha-1 sota NT repecte a MT i CT. Nivells mitjans i alts de fertilització nitrogenada augmentaren el contingut de SOC en 3.4 i 4.5 Mg C ha-1 respecte al contingut a les parcel•les no fertilitzades. L´adopció a llarg termini de pràctiques de conreu de conservació (sembra directa), juntament amb l’ús adequat de la fertilització nitrogenada van demostrar ser eines per a millorar la sostenibilitat dels nostres secans i emmagatzemar C al sòl.
El balance entre la entrada de C (de los residuos vegetales) y salidas de C (principalmente como CO2 de la descomposición del carbono orgánico del suelo -SOC-), determina el contenido de SOC, que es el mayor depósito terrestre de C. En agroecosistemas semiáridos Mediterráneos, el agua es el principal factor limitante del crecimiento del cultivo y de la entrada de residuos en el suelo. Las prácticas agronómicas alternativas pueden mejorar el crecimiento vegetal y aumentar la cantidad de residuos (entrada de C) en estos sistemas. Este trabajo estudió los efectos de la adopción a largo plazo de sistemas de laboreo (NT, no-laboreo; MT, laboreo minimo; CT, laboreo convencional) y del nivel de fertilización nitrogenada (cero; medio, 60 kg N ha-1; alto, 120 kg N ha-1) en el balance de C del suelo y el contenido de SOC. El contenido de SOC aumentó en 4.3 y 3.9 Mg C ha-1 bajo NT con respecto a MT y CT. Niveles medios y altos de fertilización nitrogenada aumentaron el contenido de SOC en 3.4 y 4.5 Mg C ha-1 con respecto al contenido en las parcelas no fertilizadas. La adopción a largo plazo de prácticas de laboreo de conservación (no-laboreo o siembra directa), junto con el uso adecuado de la fertilitzación nitrogenada demostraron ser herramientas para mejorar la sostenibilidad de los secanos semiáridos Mediterráneos y almacenar C en el suelo.
The balance between C inputs (from plant residues) and C outputs (mainly as CO2 from soil organic carbon -SOC- decomposition) determines the content of SOC which is is the largest terrestrial reservoir of carbon. Under semiarid Mediterranean agroecosystems, water limitation restrains plant growth and the return of crop residues to the soil. Alternative agronomical practices may improve crop growth and increase return of crop residue (C inputs) under these systems. This work studied the effects of long term adoption of tillage practices (NT, no-tillage; MT, minimum tillage; CT, conventional tillage) and nitrogen (N) fertilization level (zero; medium, 60 kg N ha-1; high, 120 kg N ha-1) on the SOC balance and the content of SOC. The stock of SOC was increased by 4.3 and 3.9 Mg C ha-1 under NT in comparison to MT and CT respectively. Long-term medium and high N fertilization increased the stock of SOC by 3.4 and 4.5 Mg C ha-1 in contrast to unfertilized plots. Long-term adoption of conservation tillage practices (no-tillage) together with adequate N fertilizer use, proved to be effective tools to improve sustainability of semiarid Mediterranean drylands and to store C in the soil.

ith the spread of the Green Revolution from the mid-20th century, large part of the agricultural systems in the world experienced a series of transformations that have ultimately led to important sustainability problems. Acknowledging the sustainability problems of modern industrial agriculture, this PhD thesis analyses the historical transition of a Mediterranean agroecosystem from a traditional organic management to an industrialised functioning. Understanding how this transformation affected the sustainability of the agroecosystem, changing its structure and functioning, provides useful knowledge for improving the sustainability of future agricultural systems. The theoretical perspective that grounds this thesis is formed by the interconnection of different approaches: Ecological Economics, Social Metabolism, Environmental History, Agroecology, Biocultural Landscapes and Biocultural Heritage, and Peasant Economy theories. Thus, a biophysical analysis of the historical transformation of the agroecosystem of Les Oluges (from the county of La Segarra in Lleida, Catalonia) is built for three points in time: i) c.1860, when the agroecosystem was functioning under a traditional organic management; ii) 1959, when the traditional management was mixed with the introduction of the first industrial technologies from the Green Revolution; iii) 1999, when the agroecosystem was under a completely industrialized functioning. Firstly, the analysis of the energy balances of Les Oluges agroecosystem is presented (Chapter 2). The results obtained for 1860 show an agroecosystem with a relatively low energy efficiency due to the need to reinvest large part of the energy produced in order to maintain the productive capacity of its funds. In 1959, the introduction of the first external inputs from industrial origin reduced the pressure on the local resources. The combination of industrial and traditional-organic management in 1959 improved the energy efficiency of the agroecosystem not only from a human perspective, but also for the maintenance of associated biodiversity and provision of ecosystem services. However, in 1999 the complete industrialization of the agroecosystem led to a decline of its energy efficiency that eroded its sustainability. The nutrient balances (Chapter 3) deepen and complement the previous energy balances analysis. At the aggregated scale, the results show a great enlargement of the volume of nutrients cycling in the agroecosystem in 1999; however, while in 1860 and 1959 the nutrient balances were relatively equilibrated, in 1999 there were important nutrient surpluses that reflect an over-fertilization inefficiency. The nutrient balances at the crop system scale show the different fertilization managements that were applied in cereals, woody crops and associated crop systems. Finally, this PhD thesis analyses some of the biocultural heritage from Les Oluges (Chapter 4): the intercropping system in which cereals were grown in between the lines of woody crops (mainly vines, but also olive and almond trees). The presence of this crop system in Les Oluges until de mid-20th century, as well as in other Mediterranean regions, indicate the existence of an important traditional ecological knowledge linked to this polyculture. In order to determine the possible advantages of this alley-cropping system I developed a multidimensional analysis that assesses agroecological and socioeconomic aspects. From the agroecological point of view, the results show that the intercropping system did not have a productive disadvantage. This can be explained by the weak competition among crops and the possible existence of mutual facilitation processes. Additionally, from the socioeconomic perspective the alley-cropping system provided savings in human and animal workforce, which were of great importance in the context of traditional-organic management in Les Oluges. The analysis of the traditional intercropping system in Les Oluges shows as well the adaptation of the agroecosystem’s management to a logic of peasant economy that seeks to balance multiple elements rather than maximize only one.

A three-year evaluation of crop host utilization by the tobacco budworm, Heliothis virescens (F.), was conducted from 2001 to 2003 in the central coastal plain of North Carolina. Monitoring of commercial tobacco and non-Bt cotton fields revealed spatial and temporal patterns of host use, and showed that tobacco budworm may be produced in tobacco throughout the growing season. Small plot trials conducted in 2002 and 2003 demonstrated a strong oviposition preference by tobacco budworm for tobacco when located adjacent to alternate crop hosts. The bodies of individual moths were analyzed for the presence of a cotton-specific analyte, gossypol, using high-pressure liquid chromatography?mass spectrometry/mass spectrometry (HPLC-MSMS). This technique provides a conservative estimate of tobacco budworm production on hosts other than cotton. Analysis of feral moths revealed that <10% of tobacco budworms collected in North Carolina contained gossypol. Isotope ratio mass spectrometry (IRMS) analysis of 13C/12C ratios of moths reared on four crop-plant species and two common weed species revealed a range of d13C values within that expected for plants utilizing the C3 photosynthetic pathway. Feral tobacco budworm moths collected over three years were found to have carbon isotope ratios consistent with those having fed on C3 plants. No unique carbon isotope signature was discovered that would enable a reliable determination of natal origin of feral tobacco budworm with current IRMS technology. Dose-mortality studies were conducted in 2004 to determine the susceptibility of two North Carolina strains of tobacco budworm to cypermethrin. LD50 values were 4 and 9 times greater for tobacco budworms collected in June and August respectively than for a susceptible laboratory strain. Foliar applications of pyrethroid insecticides were made to flue-cured tobacco for control of the tobacco budworm in 2001, 2002, and 2003. Pyrethroids provided significant control of tobacco budworm when compared to untreated checks in all three years of the study; however, they were generally less efficacious than the standard insecticides tested.

Orientador: Lilian Casatti
Coorientador: David J. Hoeinghaus
Banca: Dana Infante
Banca: Jani Heino
Banca: Robert Hughes
Banca: Tadeu Siqueira Barros
Resumo: Mudanças ambientais associadas a conversão da vegetação nativa em agroecossistemas são consideradas um poderoso motor de homogeneização da ictiofauna no Antropoceno. Assim, é primordial entender como subsequentes alterações em ambientes já impactados podem afetar o ambiente aquático e as assembleias de peixes. Avaliar se e como subsequentes mudanças ambientais nas escalas regional (microbacia) e local (descritores do canal e ecótone) podem afetar a estrutura taxonômica e funcional da ictiofauna e a diversidade beta espaço-temporal de riachos em agroecossistemas. Trinta e oito riachos foram amostrados em dois períodos (2003 e 2013). Nós quantificamos o grau de mudança nas escalas regional e local e, posteriormente correlacionamos com o grau de mudanças taxonômicas e funcionais das assembleias e com a diversidade beta espaço-temporal. O grau de mudanças ambientais (escalas regional e local) não foi correlacionado com as mudanças biológicas ou com a diversidade beta. A diversidade beta espacial permaneceu inalterada entre os períodos, enquanto a diversidade beta temporal foi menor do que esperado ao acaso. Os resultados obtidos nesse estudo reforçam que os padrões atuais das assembleias de peixes podem estar associados com o filtros ambientais antigos decorrente do desmatamento inicial em uma região. É provável que esses filtros foram responsáveis pela seleção não randômica de espécies generalistas quanto ao uso do habitat capazes de resistir e se adaptar a uma grande...
Abstract: Environmental changes associated with conversion of native vegetation to agroecosystems are considered a powerful drive of fish fauna homogenization in the Anthropocene. Thus, it is essential to understand how subsequent alterations to already altered ecosystems may further affect assemblages. To evaluate whether and how further environmental changes at regional (watershed) and local (instream habitat and ecotone) scales can influence taxonomic and functional fish structure and spatial-temporal beta diversity in agroecosystem streams. Thirty-eight agroecosystem streams were sampled 10 years apart (2003 and 2013). We quantified the degree of regional and local changes and correlated with the degree biological changes (taxonomic and functional structure) and with the spatial-temporal beta diversity between the two periods. The degree of environmental changes at regional and local scales were not correlated with the degree of taxonomic and functional structure changes or spatial-temporal beta diversity. Spatial beta diversity remained unchanged over time and temporal beta diversity was lower than expected by chance. We believe our results indicate that current patterns of fish assemblages in agroecosystem could be widely associated with the past deforestation and the environmental filtering. Probably, past environmental filters were responsible for the selection of habitat generalist species able to adapt and resist several types of environmental changes. Despite no pre-deforestation inventory in the region, most of our fish species are common and regionally distributed, while few rare species are restricted to few streams. In this context, it is possible that the degree of environmental changes observed in this study were not strong enough to cause further changes in fish fauna aspects. Moreover, we detected some evidence for a time lag response or legacy effects. Thus, the ...
Doutor

Les aranyes (Araneae) són un grup hiperdivers de depredadors àmpliament representat en comunitats naturals i en conreus, on s’alimenten de diferents tipus d’insectes i participen en el control biològic de plagues. Ocupen posicions intermèdies dins les xarxes tròfiques i estan implicades en interaccions intragremials amb altres depredadors. Tanmateix, la majoria d’estudis en ecologia tracten les aranyes com a un sol grup uniforme i, per tant, ignoren la gran diversitat d’interaccions interespecífiques i de connexions tròfiques en les comunitats d’artròpodes. Les xarxes tròfiques també estan influenciades per la dispersió dels individus a través del paisatge. Com que dispersar-se és costós, hom espera que els individus es basin en múltiples fonts d’informació sobre la qualitat de l’hàbitat abans de dispersar-se, però la recerca sobre la importància relativa de fonts d’informació diferents és molt escassa. Els objectius d’aquesta tesi doctoral eren, primer, estudiar les xarxes tròfiques d’artròpodes i les interaccions entre aranyes, formigues i ocells utilitzant com a sistema d’estudi un cultiu ecològic mediterrani de cítrics; segon, investigar l’efecte de la informació sobre sobre disponibilitat d’aliment i del subministrament d’aliment en la dispersió de les aranyes. Hi havia sis objectius concrets, (1) comparar l’efecte relatiu dels ocells i de les formigues en la comunitat d’aranyes; (2) comprovar l’impacte dels ocells en les aranyes diürnes i nocturnes de les capçades; (3) estudiar els efectes a llarg termini sobre la comunitat d’aranyes de les formigues que patrullen en les capçades; (4) desentrellar l’estructura de la xarxa tròfica dels artròpodes del cultiu amb anàlisis d’isòtops estables; (5) comprovar l’efecte dels indicadors de disponibilitat d’aliment en la selecció d’hàbitat i l’efecte del subministrament de preses en l’emigració de l’aranya colonial Cyrtophora citricola; i (6) contrastar la importància del subministrament de menjar a la mare i a la descendència en l’emigració a curta i a llarga distància d’Erigone dentipalpis. Durant un període de gairebé 2 anys, vam trobar que les formigues tenien un gran efecte sobre les aranyes constructores de teranyina de les famílies Araneidae and Theridiidae, mentre que no vam trobar cap efecte dels ocells. No obstant això, en un experiment d’exclusió d’ocells on vam utilitzar altres mètodes de mostreig, vam detectar una reducció dels aranèids i dels terídids causada pels ocells, la qual cosa emfasitza la importància del mostreig en el resultat dels experiments de camp en ecologia. Les dades a llarg termini també proporcionen informació essencial sobre processos ecològics: mentre que a l’inici d’un experiment de 8 anys d’exclusió de formigues, aquestes no tenien cap efecte sobre les aranyes, sí que van tenir un impacte profund sobre la comunitat d’aranyes durant els últims 4 anys: les formigues van afectar negativament l’abundància d’un ampli rang d’espècies d’aranyes independentment de la família a la qual les aranyes pertanyien. Les anàlisis d’isòtops estables van mostrar la posició tròfica de les 25 espècies més comunes d’aranyes i de les principals espècies de formigues i d’altres insectes. El nivell tròfic de les aranyes era molt més alt que el de les seves preses potencials, suggerint la prevalença de l’omnivoria i de la depredació intragremial en la xarxa tròfica. Les espècies d’aranyes de la mateixa família pertanyien a grups tròfics diferents, cosa que, juntament amb els resultats esmentats abans, mostra l’alt valor de les anàlisis a nivell d’espècie. Tant en C. citricola com en E. dentipalpis, la informació indirecta sobre la disponibilitat de menjar va tenir un paper clau en la dispersió, en contrast amb la importància limitada de la ingesta de menjar. Per tant, aquestes fonts d’informació han de ser considerades juntament amb les interaccions intragremials com a factors que influencien les poblacions d’aranyes.
Spiders (Araneae) are a hyperdiverse predator group and are widespread in both natural and arable communities, where they prey on many different types of insects and play a role in biological control. Spiders occupy intermediate positions in food webs and are involved in intraguild interactions with other predators. However, most studies treat the spider assemblage as a single uniform group, thus ignoring the sheer diversity of species interactions and trophic links within arthropod communities. Food webs are also influenced by the dispersal of individuals through the landscape. Because dispersal is costly, individuals are expected to rely on multiple sources of information about habitat quality before dispersing, although research on the relative importance of different information sources is largely lacking. The goals of this PhD thesis were first, to study arthropod food webs and the interactions between spiders, ants and birds using a Mediterranean organic citrus grove as study system; second, to investigate the effect of information about food availability and of actual food supply on spider dispersal. There were six specific objectives, namely (1) to compare the relative effect of birds and ants on the spider assemblage; (2) to test the differential impact of bird predation on diurnal and nocturnal canopy spiders; (3) to study the long-term effects of canopy-foraging ants on the spider assemblage; (4) to unravel the structure of the arthropod food web of the grove with stable isotope analyses; (5) to test the effect of cues of food availability on site-selection and of prey supply on emigration decisions of the colonial spider Cytrophora citricola; and (6) to test the importance of direct and maternal food supply on long- and short-distance emigration decisions of Erigone dentipalpis. Over an almost 2-year period, we found that ants had a strong effect on some web-building spiders of the families Araneidae and Theridiidae, whereas we did not find any effect of birds. However, in a bird exclusion experiment where we used other sampling methods, we detected a reduction of araneids and theridiids caused by birds, emphasizing the influence of sampling on the outcome of ecological field experiments. Long-term data also provided essential information about ecological processes: whereas in the beginning of an 8-year ant-exclusion experiment ants did not have any effect on spiders, they did have a pervasive impact on the spider assemblage for the last 4 years: ants negatively affected the abundance of a wide range of spider species independently of the family the spiders belonged to. Stable isotope analyses retrieved the trophic positions of the 25 most common spider species and of the main species of ants and other insects. The trophic level of spiders was much higher than that of their potential prey, suggesting a prevalence of omnivory and intraguild predation in the food web. Spider species from the same family belonged to different trophic groups, which, together with the aforementioned results, show the high value of species-level analyses. In both C. citricola and E. dentipalpis, indirect information of food availability played a key role in dispersal, in contrast to the limited importance of immediate food intake. These information sources thus need to be considered together with intraguild interactions as factors influencing spider populations.

An intensification of 200 000 tonnes of cacao is planned for the Colombian cacao production until 2021. This could lead large negative effects on the Colombian nature and biodiversity if the current smallholdings of agroforestry were abandoned in favour for large monocultures. The main objective for this study was to get general overview regarding sustainability and development challenges of the current cacao farming in Huila, Colombia. This was conducted through a minor field study in the area over eight weeks were five farms were documented together with semi-structured interviews and participatory evaluations with the farmers based on the three dimensions; environmental, economical and human. The participatory evaluations were presented by an AMOEBA methodology and even if the subjectivity of the result is a concern for the reliability, the farmers evaluations have highlighted areas of concern as well as for possibilities. Currently, practical improvements such as equipment and low income seemed to be of the greatest concerns but deeper rooted problems, such as the corruption and mistrust to the institutions could probably make a greater impact on the future development of the studied farms. On the positive side, working together in cooperatives has implicated to risen the social sustainability due to more contact and support between farmers.

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Financiadora de Estudos e Projetos
The aim of this study was to determine the occurrence of parasitoids of the major pests of maize (Zea mays L.) cultivated in different production systems. The experiment was conducted at the Embrapa Milho e Sorgo, in Sete Lagoas, State of Minas Gerais, Brazil, in conventional production systems, organic, organic intercropped with beans (Phaseolus vulgaris L.) and organic exclusive. In the collections of plants made in conventional maize and organic maize were only obtained larvae of Spodoptera frugiperda, with the emergence of the parasitoids Archytas sp.1, Archytas sp.2, Cotesia sp., Dolichozele koebelei, Eiphosoma laphygmae, Eiphosoma sp.1, Eiphosoma sp.2, Euplectrus sp., Exasticolus sp. nov., Hyphantrophaga sp. and Winthemia sp. Cremastinae species and Ophion flavidus occurred in organic maize; Campoletis sp. in conventional maize. In the ear of conventional maize and ear of organic maize were obtained larvae of Diatraea saccharalis, Dichomeris famulata, Euxesta spp., Helicoverpa zea, Megaselia seticauda and S. frugiperda. Megaselia seticauda was first reported in the ears of maize in Brazil. The parasitoids obtained from the ears of conventional maize and organic maize in S. frugiperda were: Hyphantrophaga sp. occurring in both areas, Glyptapanteles sp. only in the conventional maize and Microcharops sp. only in the organic maize, for H. zea in the organic maize parasitized larvae were not obtained, in the conventional maize, occurred the parasitoids Aleiodes sp. and Copidosoma sp. Apanteles sp. and Phanerotoma sp. occurred on D. famulata in the conventional maize and organic maize; Chelonus (Microchelonus) sp. nov., Microcharops sp. and Perilampus sp. occurred only in the conventional maize. Apsilophrys sp. occurred only in organic maize. These are the first records of Apanteles sp., Chelonus (Microchelonus) sp. nov., Microcharops sp., Perilampus sp. and Phanerotoma sp. on D. famulata. In Euxesta spp. in the organic maize were not obtained larvaes killed by parasitoids in the conventional maize on Euxesta spp. occurred the parasitoid Dettmeria sp. About D. saccharalis and M. seticauda, there were not obtained parasitoids. In the collections of stalks of conventional maize and organic maize, there was a prevalence of D. saccharalis, S. frugiperda occurred only in conventional maize. There were not observed larvaes of S. frugiperda killed by parasitoids, but for D. saccharalis, occurred, in two areas, the parasitoid Lixophaga sp. In the collections of plants, in the organic maize exclusive and organic maize intercropped with beans, the parasitoids obtained from the larvae of S. frugiperda were Archytas sp., Campoletis sp., Cotesia sp., D. koebelei, E. laphygmae, Eiphosoma sp.1, Eiphosoma sp.2, Eiphosoma sp.3, Eiphosoma sp.4, Eiphosoma sp.5, Glyptapanteles sp., Microcharops sp. and O. flavidus. The parasitoids Aprostocetus sp., Chelonus insularis, Colpotrochia sp. nov. and Ichneumoninae were observed only in the exclusive organic maize, while Apanteles sp. and Eiphosoma sp.6 only in the organic maize intercropped with beans. From the pests of the ear of maize collected in the organic maize exclusive and in the organic maize intercropped with beans occurred larvaes of D. famulata, Euxesta spp., H. zea, M. seticauda and S. frugiperda. From these only larvaes of H. zea and D. famulata were parasitized. The index of parasitism of H. zea by Archytas sp. was similar in both areas, the parasitoid of D. famulata, Apsilophrys sp. was observed in all samples of organic maize intercropped with beans, but it did not occur in any collection of the exclusive organic maize. In these samples were not obtained for parasitoids Euxesta spp., M. seticauda and S. frugiperda. In the collections of stalks in organic maize exclusive and organic maize intercropped with beans were obtained only larvaes of D. saccharalis without the occurrence of parasitoids. In both experiments the number of larvaes of the pests collected was low, new associations and new species of parasitoids reported represent the possibility of the exploitation of these natural enemies in the control of pests in the culture of maize.
O objetivo deste estudo foi determinar a ocorrência de parasitoides das principais pragas de milho (Zea mays L.) cultivado em diferentes sistemas de produção. O experimento foi conduzido na Embrapa Milho e Sorgo em Sete Lagoas, Minas Gerais (MG), Brasil, em sistemas de produção convencional, orgânico, orgânico consorciado com feijão (Phaseolus vulgaris L.) e orgânico solteiro. Nas coletas de plantas realizadas no milho convencional e no milho orgânico só foram obtidas larvas de Spodoptera frugiperda, com a emergência dos parasitoides Archytas sp.1, Archytas sp.2, Cotesia sp., Dolichozele koebelei, Eiphosoma laphygmae, Eiphosoma sp.1, Eiphosoma sp.2, Euplectrus sp., Exasticolus sp. nov., Hyphantrophaga sp. e Winthemia sp. Espécies de Cremastinae e Ophion flavidus ocorreram no milho orgânico; Campoletis sp., no milho convencional. Nas espigas de milho convencional e de milho orgânico foram obtidas larvas de Diatraea saccharalis, Dichomeris famulata, Euxesta spp., Helicoverpa zea, Megaselia seticauda e S. frugiperda. Megaselia seticauda foi registrada pela primeira vez em espigas de milho no Brasil. Os parasitoides obtidos das espigas no milho convencional e no milho orgânico em S. frugiperda foram: Hyphantrophaga sp. ocorrendo nas duas áreas; Glyptapanteles sp., apenas no milho convencional; e Microcharops sp., somente no milho orgânico; para H. zea no milho orgânico não foram obtidas larvas parasitadas, no milho convencional, ocorreram os parasitoides Aleiodes sp. e Copidosoma sp., Apanteles sp. e Phanerotoma sp. ocorreram sobre D. famulata no milho convencional e no milho orgânico; Chelonus (Microchelonus) sp. nov., Microcharops sp. e Perilampus sp. ocorreram apenas no milho convencional; Apsilophrys sp., ocorreu somente no milho orgânico. Esses são os primeiros registros de Apanteles sp., Chelonus (Microchelonus) sp. nov., Microcharops sp., Perilampus sp. e Phanerotoma sp. sobre D. famulata. Em Euxesta spp. no milho orgânico não foram obtidas larvas mortas por parasitoides, no milho convencional sobre Euxesta spp. ocorreu o parasitoide Dettmeria sp. Sobre D. saccharalis e M. seticauda, não foram obtidos parasitoides. Nas coletas de colmos em milho convencional e no milho orgânico, houve prevalência de D. saccharalis. Não foram observadas larvas de S. frugiperda mortas por parasitoides, já para D. saccharalis, ocorreu, nas duas áreas, o parasitoide Lixophaga sp. Nas coletas de plantas, no milho orgânico solteiro e no milho orgânico consorciado com feijão, os parasitoides obtidos das larvas de S. frugiperda foram Archytas sp., Campoletis sp., Cotesia sp., D. koebelei, E. laphygmae, Eiphosoma sp.1, Eiphosoma sp.2, Eiphosoma sp.3, Eiphosoma sp.4, Eiphosoma sp.5, Glyptapanteles sp., Microcharops sp. e O. flavidus. Já os parasitoides Aprostocetus sp., Chelonus insularis, Colpotrochia sp. nov. e Ichneumoninae foram observados somente no milho orgânico solteiro, enquanto Apanteles sp. e Eiphosoma sp.6 apenas no milho orgânico consorciado com feijão. Quanto às pragas da espiga coletadas no milho orgânico solteiro e no milho orgânico consorciado com feijão ocorreram larvas de D. famulata, Euxesta spp., H. zea, M. seticauda e S. frugiperda. Destas apenas larvas de H. zea e de D. famulata foram parasitadas. O índice de parasitismo de H. zea por Archytas sp. foi semelhante nas duas áreas; o parasitoide de D. famulata, Apsilophrys sp., foi observado em todas as coletas do milho orgânico consorciado com feijão, mas não ocorreu em nenhuma coleta do milho orgânico solteiro. Nessas coletas não foram obtidos parasitoides para Euxesta spp., M. seticauda e S. frugiperda. Nas coletas de colmos em milho orgânico solteiro e no milho orgânico consorciado com feijão foram obtidas apenas larvas de D. saccharalis sem a ocorrência de parasitoides. Nos dois experimentos o número de larvas das pragas coletadas foi baixo, as novas associações e as novas espécies de parasitoides relatadas representam a possibilidade de utilização desses inimigos naturais no controle de pragas na cultura do milho.

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O objetivo geral desta pesquisa foi avaliar a sustentabilidade da caprinocultura nos municípios de São João do Cariri e São José dos Cordeiros, estado da Paraíba, fazendo-se o uso da metodologia MESMIS. Na pesquisa foram realizadas visitas em 30 propriedades localizadas nos municípios supracitados, na região semiárida do Estado, nos meses de junho e julho de 2017, utilizando-se questionários semiestruturados junto ao público alvo, os produtores de caprinos. A metodologia adotada foi proposta pela ferramenta MESMIS, que permitiu avaliar a sustentabilidade dos agroecossistemas considerando aspectos: ambientais sociais e econômicos dos produtores e suas famílias que tem na caprinocultura, a principal atividade produtiva. Os dados obtidos foram analisados por meio da estatística de análise multivariada, submetidas à distribuição de frequência, análise de correspondência múltipla e de agrupamento. A utilização da metodologia MESMIS permitiu a utilização de indicadores que possibilitaram a avaliação da sustentabilidade dos agroecossistemas desenvolvidos nas unidades de produção em caráter familiar que foram o objeto de estudo dessa pesquisa a partir de uma visão holística considerando fatores relacionados não só as questões sociais como também ambientais e econômicas. Possibilitando a observação dos pontos positivos e negativos da atividade produtiva estudada e as medidas tomadas no intuito de promover um desenvolvimento mais sustentável da mesma. A partir dos fatores elencados em cada uma das três categorias, foi possível observar que mesmo diante da escassez hídrica vivenciada pelos os municípios estudados, nos últimos anos, os produtores vêm caminhando em direção da sustentabilidade dos agroecossistemas, a partir da superação das limitações que se apresentaram em cada categoria analisada.
The general objective of this research was to evaluate the sustainability of goat breeding in the municipalities of São João do Cariri and São José dos Cordeiros, state of Paraíba, using the MESMIS methodology. In the survey, visits were made to 30 properties located in the aforementioned municipalities, in the semi-arid region of the State, in the months of June and July 2017, using semi-structured questionnaires with the target public, goat producers. The methodology adopted was proposed by the MESMIS tool, which allowed the evaluation of the sustainability of agroecosystems considering the social and economic environmental aspects of the producers and their families that have the main production activity in goat farming. The data obtained were analyzed using multivariate analysis statistics, submitted to frequency distribution, multiple correspondence analysis and clustering. The use of the MESMIS methodology allowed the use of indicators that enabled the evaluation of the sustainability of the agroecosystems developed in the family units that were the object of study of this research from a holistic view considering factors related not only to social issues but also environmental and economic conditions. Making it possible to observe the positive and negative points of the productive activity studied and the measures taken in order to promote a more sustainable development of the same. Based on the factors listed in each of the three categories, it was possible to observe that even in the face of the water scarcity experienced by the studied municipalities, in recent years, farmers have been moving toward the sustainability of agroecosystems, by overcoming the limitations that presented in each category analyzed.

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Greater stability of an agroecosystem can be achieved through the consortium system under organic management, becomes an important environmental factor to a highest stability of the agroecosystem. The objective was to study a system of production for organic crops of maize (Zea mays L., cv. BR 106), bean (Phaseolus vulgaris L., cultivar IAC Pérola) and manioc (Manihot esculenta CRANTZ, cv. IAC 15), intercropped with ratoon-cane (Saccharum spp.). The experimental design was a randomized, with eight (8) treatments and four (4) replicates, as follows: T1 ratoon-cane without intercropping (control), T2: ratooncane and intercropping of maize (cs + mi), T3: ratoon-cane and intercropping of bean (cs + fe); T4: ratoon-cane and intercropping of manioc (cs + ma), T5: ratooncane and intercrops of maize and bean (cs + mi + fe) T6: ratoon-cane and intercrops of maize and manioc (cs + mi + ma); T7 ratoon-cane and intercrops of bean and manioc (cs + f + ma), T8: ratoon-cane and intercrops of maize, bean and manioc (cs + mi + fe + ma). Productivity of the crops, the gross income obtained and the residual biomass waste of maize, beans and manioc, in each system were evaluated. For the conditions of the experiment, the treatment intercropping maize (T2) showed the best results on productivity of green maize ears (kg/ha), production of biomass (kg/ha) and gross income (R$/ha). The alternative of the consortium of distinct crops with ratoon-cane proves to be an effective technique that, from the viewpoint of agroecology, becomes an important tool for preserving and maintaining the agroecosystem, besides providing alternative foods and additional income to the farmer.
Maior estabilidade do agroecossistema pode ser obtida através do plantio consorciado, o qual, sob manejo orgânico, torna-se um fator ambiental que pode ser utilizado como complemento a outras técnicas de cultivo. O objetivo foi estudar um sistema de produção orgânico de milho (Zea mays L., variedade BR 106), feijão (Phaseolus vulgaris L., cultivar IAC Pérola) e mandioca (Manihot esculenta CRANTZ, variedade IAC 15) consorciados com soqueiras da cultura de cana-deaçúcar (Saccharum spp.). O delineamento estatístico utilizado foi o de blocos casualizados, contando com oito (8) tratamentos e quatro (4) repetições, sendo T1: cana-soca sem cultura intercalar (testemunha); T2: cana-soca e cultura intercalar de milho (cs+mi); T3: cana-soca e cultura intercalar de feijão (cs+fe); T4: cana-soca e cultura intercalar de mandioca (cs+ma); T5: cana-soca e culturas intercalares de milho e feijão (cs+mi+fe); T6: cana-soca e culturas intercalares de milho e mandioca (cs+mi+ma); T7: cana-soca e culturas intercalares de feijão e mandioca (cs+fe+ma); T8: cana-soca e culturas intercalares de milho, feijão e mandioca (cs+mi+fe+ma). Avaliou-se a produtividade das culturas, a renda bruta estimada e a biomassa residual de milho, feijão e mandioca, em cada sistema. Para as condições do experimento, o tratamento cultura intercalar de milho (T2) apresentou os melhores resultados quanto à produtividade de espigas verdes (kg/ha), a produção de biomassa (kg/ha) e renda bruta estimada (R$/ha). A alternativa do consórcio de diferentes culturas com soqueira de cana-de-açúcar demonstra ser uma técnica eficiente que, sob a ótica da agroecologia, se torna uma ferramenta importante na preservação e manutenção do agroecossistema, além de proporcionar alimento e renda adicional para o agricultor familiar.

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Greater stability of an agroecosystem can be achieved through the consortium system under organic management, becomes an important environmental factor to a highest stability of the agroecosystem. The objective was to study a system of production for organic crops of maize (Zea mays L., cv. BR 106), bean (Phaseolus vulgaris L., cultivar IAC Pérola) and manioc (Manihot esculenta CRANTZ, cv. IAC 15), intercropped with ratoon-cane (Saccharum spp.). The experimental design was a randomized, with eight (8) treatments and four (4) replicates, as follows: T1 ratoon-cane without intercropping (control), T2: ratooncane and intercropping of maize (cs + mi), T3: ratoon-cane and intercropping of bean (cs + fe); T4: ratoon-cane and intercropping of manioc (cs + ma), T5: ratooncane and intercrops of maize and bean (cs + mi + fe) T6: ratoon-cane and intercrops of maize and manioc (cs + mi + ma); T7 ratoon-cane and intercrops of bean and manioc (cs + f + ma), T8: ratoon-cane and intercrops of maize, bean and manioc (cs + mi + fe + ma). Productivity of the crops, the gross income obtained and the residual biomass waste of maize, beans and manioc, in each system were evaluated. For the conditions of the experiment, the treatment intercropping maize (T2) showed the best results on productivity of green maize ears (kg/ha), production of biomass (kg/ha) and gross income (R$/ha). The alternative of the consortium of distinct crops with ratoon-cane proves to be an effective technique that, from the viewpoint of agroecology, becomes an important tool for preserving and maintaining the agroecosystem, besides providing alternative foods and additional income to the farmer.
Maior estabilidade do agroecossistema pode ser obtida através do plantio consorciado, o qual, sob manejo orgânico, torna-se um fator ambiental que pode ser utilizado como complemento a outras técnicas de cultivo. O objetivo foi estudar um sistema de produção orgânico de milho (Zea mays L., variedade BR 106), feijão (Phaseolus vulgaris L., cultivar IAC Pérola) e mandioca (Manihot esculenta CRANTZ, variedade IAC 15) consorciados com soqueiras da cultura de cana-deaçúcar (Saccharum spp.). O delineamento estatístico utilizado foi o de blocos casualizados, contando com oito (8) tratamentos e quatro (4) repetições, sendo T1: cana-soca sem cultura intercalar (testemunha); T2: cana-soca e cultura intercalar de milho (cs+mi); T3: cana-soca e cultura intercalar de feijão (cs+fe); T4: cana-soca e cultura intercalar de mandioca (cs+ma); T5: cana-soca e culturas intercalares de milho e feijão (cs+mi+fe); T6: cana-soca e culturas intercalares de milho e mandioca (cs+mi+ma); T7: cana-soca e culturas intercalares de feijão e mandioca (cs+fe+ma); T8: cana-soca e culturas intercalares de milho, feijão e mandioca (cs+mi+fe+ma). Avaliou-se a produtividade das culturas, a renda bruta estimada e a biomassa residual de milho, feijão e mandioca, em cada sistema. Para as condições do experimento, o tratamento cultura intercalar de milho (T2) apresentou os melhores resultados quanto à produtividade de espigas verdes (kg/ha), a produção de biomassa (kg/ha) e renda bruta estimada (R$/ha). A alternativa do consórcio de diferentes culturas com soqueira de cana-de-açúcar demonstra ser uma técnica eficiente que, sob a ótica da agroecologia, se torna uma ferramenta importante na preservação e manutenção do agroecossistema, além de proporcionar alimento e renda adicional para o agricultor familiar.

This study examines agriculture in the Inner Bluegrass Region of Central Kentucky from 1850 to 1880. It utilizes an agroecological perspective, which interprets agriculture through the lens of ecology, to highlight the complex natural and cultural factors that combined to form one of the nation's most prosperous agricultural systems during the nineteenth century. Chapter One explores the agroecosytem Bluegrass farmers created and maintained, emphasizing dynamics in crop and livestock diversity and agricultural technology. Chapter Two examines the African-American labor force that played a key role in shaping the system, first as slaves and later as free men and women. Chapter Three addresses the cultural outlooks and institutions that influenced land use patterns, ranging from beliefs on proper methods of cultivation to voluntary organizations designed to facilitate market access. Through an examination of the various influences at work on the agricultural environment, the landscape emerges as a dynamic factor, rather than a passive backdrop, in Inner Bluegrass history.

The Upper Mississippi River (UMR) basin contributes over 50,000 metric tons of nitrogen (N) to the Gulf of Mexico each year, resulting in a “dead zone” inhospitable to aquatic life. Land-applied N (fertilizer) in the corn-belt is attributed with a majority of the N-load reaching the Gulf and is difficult to treat as run-off is considered a non-point source of pollution (i.e. not from a pipe). One solution to this “grand challenge” of intercepting N pollution is utilizing filter-feeding organisms native to the UMR. Freshwater mussel (order Unionidae) assemblages collectively filter over 14 billion gallons of water, remove tons of biomass from overlying water, and sequester tons of N each day. Our previous research showed mussel excretions increased the sediment porewater concentrations of ammonium by 160%, and indirectly increased nitrate and nitrite by 40%, presumably from microbial degradation of ammonium. In response, the goal of this research was to characterize how mussels influenced microbial communities (microbiome) to determine the fate of N in UMR sediment. First, we used qPCR and non-targeted amplicon sequencing within sediment layers to identify the N-cycling microbiome and characterized microbial community changes attributable to freshwater mussels. qPCR identified that anaerobic ammonium oxidizing (anammox) bacteria were increased by a factor of 2.2 at 3 cm below the water-sediment interface when mussels were present. Amplicon sequencing of sediment at depths relevant to mussel burrowing (3 and 5 cm) showed that mussel presence reduced microbial species richness and diversity and indicated that sediment below mussels harbored distinct microbial communities. Furthermore, mussels increased the abundance of ammonia oxidizing bacteria (family Nitrosomonadaceae), nitrite oxidizing bacteria (genus Nitrospira), but decreased the abundance of ammonia oxidizing archaea (genus Candidatus Nitrososphaera), and microorganisms which couple denitrification with methane oxidation. These findings suggested that mussels may enhance microbial niches at the interface of oxic and anoxic conditions, presumably through excretion of N and burrowing activity. In response, we performed metagenomic shotgun sequencing to identify which genes of the microbiome were most impacted by mussels. We hypothesized that genes responsible for ammonia and nitrite oxidation would be greater in the sediment with mussel assemblages. We found the largest abundance of N-cycling genes were responsible for nitrate reduction and nitrite oxidation, which is corroborated by the high concentration of nitrates in UMR water. Linear discriminant analysis statistical analyses showed nitrification genes were most impacted by mussels, and this presented an opposing effect on genes responsible for producing nitrous oxide, a potent greenhouse gas. Further investigation showed an increased abundance of a novel organism capable of completely oxidizing ammonia to nitrate (Candidatus Nitrospira inopinata) and coexisted with metabolically flexible Nitrospira (sp. moscoviensis), likely enhancing both carbon and N-cycling. We demonstrated that native mussels harbor a unique niche for N-cycling microorganisms with large metabolic potentials to degrade mussel excretion products. Our findings suggest the ecosystem services of mussels extend beyond water filtration, and includes enhanced biogeochemical cycling of carbon, N, and reduces the potential for a potent microbially-produced greenhouse gas. Ultimately, this research could be used to advocate for mussel habitat restoration in the UMR to lessen the impacts of non-point pollution.