Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Espécies exóticas invasoras são consideradas uma das maiores ameaças à biodiversidade, à saúde humana, aos bens e recursos humanos. E, por isso, seu enfrentamento envolve uma ampla gama de instituições atuantes e instrumentos legais. Objetivando contribuir para a formulação e a implementação de uma política pública de enfrentamentos das espécies exóticas invasoras no território brasileiro, o presente estudo foi conduzido a partir de uma análise de dados secundários, que incluiu documentos governamentais, publicações científicas e da legislação aplicável a fim de demonstrar a tese de que os atuais problemas socioambientais, dentre eles as bioinvasões, materializam os desafios do enfrentamento da complexidade dos mesmos, cujas respostas demandam ações articuladas capazes de integrar os conhecimentos técnico-científicos, a legislação aplicável e o arcabouço institucional, sem negligenciar a participação pública dos atores sociais envolvidos no processo de formulação e implementação da política pública. Os resultados indicam que o Brasil vive um cenário de risco ambiental devido a inexistência de ações integradas de enfrentamento do problema. A análise comparada da estrutura brasileira com a de outros três países (África do Sul, Estados Unidos da América e Nova Zelândia) permite constatar que fatores como dimensão do território, estrutura governamental de enfrentamento do problema, coerência entre o arcabouço legal e institucional e disponibilidade de informações científicas coerentes são em conjunto importantes para o sucesso das respostas nacionais ao problema, mas isoladamente não são capazes de explicar tal sucesso. A comparação reforça a tese sobre a importância da retroalimentação da tríade formada pelo conhecimento científico, arcabouço institucional e estrutura jurídica para a resposta às bioinvasões. Os avanços científicos deveriam ser catalisadores do aprimoramento da legislação, que para ser eficiente precisaria prover as instituições de sólidos instrumentos de atuação. Ao aprimorar as suas legislações, os países necessariamente precisariam observar as funções que estes instrumentos cumprem sobre outros aspectos e setores da sociedade e as limitações impostas pela convivência global gerida a partir de acordos internacionais. Como observado a partir da análise do Convention on Biological Diversity e do International Plant Protection Convention, acordos internacionais trouxeram importantes avanços à capacidade brasileira de enfrentamento das bioinvasões. Mas, eles também podem limitar a atuação nacional, especialmente no que diz respeito a adoção de medidas preventivas mais rigorosas. Já uma análise comparada das Políticas Nacionais de Meio Ambiente, de Recursos Hídricos e Agrícola permitiu a identificação de alguns pontos domésticos importantes na formulação e na implementação de uma política de enfrentamento das bioinvasões, dentre os quais estacam-se: a ampla inclusão de atores afetos ao tema, a instalação de arenas de discussão que incorporem as múltiplas visões e dimensões do tema e a integração dos avanços científicos aos instrumentos normativos e aos sistemas operacionais de implantação das políticas. Conclui-se afirmando que, apesar dos avanços científicos, legais e institucionais no enfrentamento das bioinvasões, há notável desarticulação entre estes componentes. E, mais do que instituir uma política pública através de um instrumento legal, deveria ser priorizada a integração efetiva dos supracitados elementos para que se assegure a consistência das ações e a eficiência prática dessa política. / Invasive exotic species are considered one of the greatest threats because they can affect simultaneously biodiversity and human health, property and resources. Therefore, efforts in confronting such species engage a wide range of institutions and legal instruments. In order to contribute to the formulation and implementation of public policies to confront invasive exotic species in the Brazilian territory, this study analyzed secondary data such as government documents, scientific publications and legal instruments, aims to demonstrate the thesis that actual socioenvironmental problems, among them bioinvasions, demands articulated actions capable to integrating technical-scientific knowledge, the applicable legislation and the institutional framework, without neglecting public participation of social actors involved in the process of formulation and implementation of public policy. Results point that Brazil is going through an environmental risk scenario due to the lack of integrated actions to confront the problem. The comparative analysis between the Brazilian structure and that of three other countries (South Africa, United States of America and New Zealand) shows that factors such as size of territory, governmental structure to confront the problem, coherence between the legal and institutional framework and the availability of scientific information jointly are important to the success of national responses to the problem, but individually are not able to explain such success. This comparison reinforces the theory about the importance of integration of scientific knowledge, institutional framework and legal structure for an effective response to bioinvasions. Scientific advances should be catalysts of improvements to legal acts, which in order to be efficient should provide institutions with structured action instruments. In order to improve its legislation, a country needed observe the roles such instruments have on other aspects and sectors of society and the limitations imposed by global coexistence managed by international agreements. Analyses of the Convention on Biological Diversity and International Plant Protection Convention show that international agreements brought important advances to Brazilian capacity to confront bioinvasions. However, such international agreement may limit national acts, especially regarding the adoption of more stringent preventive measures. Additionally, a comparative analysis between Environmental, Water Resources and Agricultural National Policies has allowed the identification of some important domestic points in the formulation and implementation of a public policies to confront bioinvasions, including: wide inclusion of actors involved with the theme, establishment of arenas of discussion that incorporate multiple views and dimensions of the theme and integration of scientific advances to regulatory instruments and operating systems in the implementation of the policies. In conclusion, despite advances in scientific, legal and institutional confrontation of bioinvasions, there is remarkable disconnectivity between these components. Thus, besides the establishment of public policies through legal instruments, the effective integration of these components should be prioritized to ensure consistency of action and efficient practice of such policies.

Made available in DSpace on 2016-06-02T19:02:40Z (GMT). No. of bitstreams: 1 3890.pdf: 2739392 bytes, checksum: fdb93cb69cafb89992f3e6a155deacfb (MD5) Previous issue date: 2011-10-21 / The Biosafety is a very important tool for the Control of Hospital Infection establishing through methods, techniques and standards, measures to be adopted in order to prevent and control risks that may contribute to hospital infection. This work reports the development of an impedimetric immunosensor for detection of pathogenic bacteria, specifically Staphylococcus aureus (S. aureus), in hospital critical areas (Surgical Centers and Intensive Care Units) to contribute to the hospital infection control. Different parameters were studied: direct immobilization of protein A of S. aureus on the surface of the transducer or the working electrode (screen-printed electrode - SPE), immobilization of protein A on SPEs modified with self-assembled monolayers (SAMs) of cystamine (CYS) and glutaraldehyde (GA); different incubation times and dilutions were used for both modifiers as for protein A and anti- S. aureus antibodies; blocking with bovine serum albumin (BSA) and immunoassay (antigen-antibody reaction, Ag-Ab). Electrochemical techniques (electrochemical impedance spectroscopy - EIS and cyclic voltammetry - CV) and non electrochemical (microscopy) were used for the characterization and construction of the immunosensor. The impedance measurements and cyclic voltammetry showed the good results with self-assembled monolayer of cystamine 2 x 10-2 mol L-1 and glutaraldehyde 2,5% with incubation periods of 2 and 1h, respectively; immobilization of protein A 1:20 (tincub = 12 h) and anti-S. aureus monoclonal Ab (tincub = 3 h) and step blocking with 0.5% BSA (tincub = 1 h). For the Ag-Ab interaction S. aureus ATCC - 6535 strains (analyte) were used and incubation for 30 min. The immunosensor developed has proven to be an effective method for monitoring of S. aureus in a hospital environment and that can be applied as an indicative tool of the effectiveness of the standards and procedures applied to the control of hospital infection. / A Biossegurança constitui uma ferramenta de grande relevância para o Controle da Infecção Hospitalar estabelecendo através de métodos, técnicas e normas, condutas a serem adotadas com o intuito de prevenir e controlar os riscos que podem favorecer à infecção hospitalar. Este trabalho relata o desenvolvimento de um imunossensor impedimétrico para detecção de Staphylococcus aureus (S. aureus), em áreas críticas hospitalares (Centros Cirúrgicos e Unidades de Terapia Intensiva) visando contribuir para o controle de infecção hospitalar. Diferentes parâmetros foram estudados: imobilização direta da proteína A de S. aureus na superfície do transdutor ou eletrodo de trabalho (screen-printed electrode - SPE); imobilização da proteína A sobre SPEs modificados com monocamadas auto-organizadas (SAMs) de cistamina (CYS) e glutaraldeído (GA); diferentes tempos de incubação e diluições foram utilizados tanto para os modificadores como para a proteína A e anticorpos anti-S. aureus; bloqueio com soroalbumina bovina (SAB) e imunoensaio (reação antígeno-anticorpo, Ag-Ac). Técnicas eletroquímicas (espectroscopia de impedância eletroquímica - EIS e voltametria cíclica - VC) e não eletroquímicas (microscopias) foram utilizadas para a caracterização e construção do imunossensor. As medidas de impedância e voltametria cíclica mostraram bons resultados com monocamadas auto-organizadas de cistamina 2 x 10-2 mol L-1 e glutaraldeído 2,5% com tempos de incubação de 2 e 1 h, respectivamente;assim como as imobilizações da proteína A 1:20 (tincub = 12 h); Ac monoclonais anti-S. aureus (tincub = 3 h) e etapa de bloqueio com SAB 0,5% (tincub = 1 h). Na interação Ag-Ac utilizou-se cepas de S. aureus ATCC - 6535 (analito) e incubação de 30 min. O imunossensor desenvolvido indicou ser um método efetivo para monitoramento de S. aureus em ambiente hospitalar e que pode ser aplicado como instrumento indicativo da efetividade das normas e condutas aplicadas para o controle de infecção hospitalar.

Espécies exóticas invasoras são consideradas uma das maiores ameaças à biodiversidade, à saúde humana, aos bens e recursos humanos. E, por isso, seu enfrentamento envolve uma ampla gama de instituições atuantes e instrumentos legais. Objetivando contribuir para a formulação e a implementação de uma política pública de enfrentamentos das espécies exóticas invasoras no território brasileiro, o presente estudo foi conduzido a partir de uma análise de dados secundários, que incluiu documentos governamentais, publicações científicas e da legislação aplicável a fim de demonstrar a tese de que os atuais problemas socioambientais, dentre eles as bioinvasões, materializam os desafios do enfrentamento da complexidade dos mesmos, cujas respostas demandam ações articuladas capazes de integrar os conhecimentos técnico-científicos, a legislação aplicável e o arcabouço institucional, sem negligenciar a participação pública dos atores sociais envolvidos no processo de formulação e implementação da política pública. Os resultados indicam que o Brasil vive um cenário de risco ambiental devido a inexistência de ações integradas de enfrentamento do problema. A análise comparada da estrutura brasileira com a de outros três países (África do Sul, Estados Unidos da América e Nova Zelândia) permite constatar que fatores como dimensão do território, estrutura governamental de enfrentamento do problema, coerência entre o arcabouço legal e institucional e disponibilidade de informações científicas coerentes são em conjunto importantes para o sucesso das respostas nacionais ao problema, mas isoladamente não são capazes de explicar tal sucesso. A comparação reforça a tese sobre a importância da retroalimentação da tríade formada pelo conhecimento científico, arcabouço institucional e estrutura jurídica para a resposta às bioinvasões. Os avanços científicos deveriam ser catalisadores do aprimoramento da legislação, que para ser eficiente precisaria prover as instituições de sólidos instrumentos de atuação. Ao aprimorar as suas legislações, os países necessariamente precisariam observar as funções que estes instrumentos cumprem sobre outros aspectos e setores da sociedade e as limitações impostas pela convivência global gerida a partir de acordos internacionais. Como observado a partir da análise do Convention on Biological Diversity e do International Plant Protection Convention, acordos internacionais trouxeram importantes avanços à capacidade brasileira de enfrentamento das bioinvasões. Mas, eles também podem limitar a atuação nacional, especialmente no que diz respeito a adoção de medidas preventivas mais rigorosas. Já uma análise comparada das Políticas Nacionais de Meio Ambiente, de Recursos Hídricos e Agrícola permitiu a identificação de alguns pontos domésticos importantes na formulação e na implementação de uma política de enfrentamento das bioinvasões, dentre os quais estacam-se: a ampla inclusão de atores afetos ao tema, a instalação de arenas de discussão que incorporem as múltiplas visões e dimensões do tema e a integração dos avanços científicos aos instrumentos normativos e aos sistemas operacionais de implantação das políticas. Conclui-se afirmando que, apesar dos avanços científicos, legais e institucionais no enfrentamento das bioinvasões, há notável desarticulação entre estes componentes. E, mais do que instituir uma política pública através de um instrumento legal, deveria ser priorizada a integração efetiva dos supracitados elementos para que se assegure a consistência das ações e a eficiência prática dessa política. / Invasive exotic species are considered one of the greatest threats because they can affect simultaneously biodiversity and human health, property and resources. Therefore, efforts in confronting such species engage a wide range of institutions and legal instruments. In order to contribute to the formulation and implementation of public policies to confront invasive exotic species in the Brazilian territory, this study analyzed secondary data such as government documents, scientific publications and legal instruments, aims to demonstrate the thesis that actual socioenvironmental problems, among them bioinvasions, demands articulated actions capable to integrating technical-scientific knowledge, the applicable legislation and the institutional framework, without neglecting public participation of social actors involved in the process of formulation and implementation of public policy. Results point that Brazil is going through an environmental risk scenario due to the lack of integrated actions to confront the problem. The comparative analysis between the Brazilian structure and that of three other countries (South Africa, United States of America and New Zealand) shows that factors such as size of territory, governmental structure to confront the problem, coherence between the legal and institutional framework and the availability of scientific information jointly are important to the success of national responses to the problem, but individually are not able to explain such success. This comparison reinforces the theory about the importance of integration of scientific knowledge, institutional framework and legal structure for an effective response to bioinvasions. Scientific advances should be catalysts of improvements to legal acts, which in order to be efficient should provide institutions with structured action instruments. In order to improve its legislation, a country needed observe the roles such instruments have on other aspects and sectors of society and the limitations imposed by global coexistence managed by international agreements. Analyses of the Convention on Biological Diversity and International Plant Protection Convention show that international agreements brought important advances to Brazilian capacity to confront bioinvasions. However, such international agreement may limit national acts, especially regarding the adoption of more stringent preventive measures. Additionally, a comparative analysis between Environmental, Water Resources and Agricultural National Policies has allowed the identification of some important domestic points in the formulation and implementation of a public policies to confront bioinvasions, including: wide inclusion of actors involved with the theme, establishment of arenas of discussion that incorporate multiple views and dimensions of the theme and integration of scientific advances to regulatory instruments and operating systems in the implementation of the policies. In conclusion, despite advances in scientific, legal and institutional confrontation of bioinvasions, there is remarkable disconnectivity between these components. Thus, besides the establishment of public policies through legal instruments, the effective integration of these components should be prioritized to ensure consistency of action and efficient practice of such policies.

El presente proyecto ostenta una alternativa de negocio que tiene como propósito favorecer la seguridad sanitaria, de modo que busca satisfacer las necesidades que actualmente el mercado peruano exige, en cuanto a limpieza y desinfección de oficinas y negocios en general. Es por ello que nace la idea de implementar un modelo de negocio llamado JLAS “Join Life Absolute Safe” que tiene como finalidad realizar trabajos de desinfección brindando alternativas que se puedan ajustar a las necesidades actuales de las empresas que requieran nuestro servicio. Para ello se impulsó la validación y exploración de mercado en el cual se identificó la problemática y su posible solución, los cuales han sido validados a través de herramientas como el desarrollo de una Landing Page, desarrollo de PMV (Producto Mínimo Viable) y entrevistas, los cuales nos ayudaron a recabar información beneficiosa para continuar con nuestro proyecto. Por otro lado, hemos asentado nuestras estrategias de manera que nuestra propuesta parezca lo más real posible, ya que hemos analizado e implementado nuestro plan de operaciones, comercial, nuestro plan de marketing y la distribución organizacional para un periodo de 5 años, en el cual se detallaran todos los aspectos competentes y organizacionales que envuelven el proceso de implementación del presente proyecto. Finalmente, se realizó un análisis financiero, el cual demostró que a través de indicadores económicos la viabilidad del proyecto, por lo tanto, se llegó a la conclusión de que el presente modelo de negocio es conveniente. / The present project has a business alternative that has the purpose of favoring sanitary safety, so that it seeks to satisfy the needs that the Peruvian market currently demands, in terms of cleaning and disinfection of offices and businesses in general. That is why the idea of implementing a business model called JLAS "Join Life Absolute Safe" was born. Its purpose is to carry out disinfection work by providing alternatives that can be adjusted to the current needs of companies that require our service. For this purpose, we promoted the validation and exploration of the market in which the problem and its possible solution were identified, which have been validated through tools such as the development of a Landing Page, development of MVP (Minimum Viable Product) and interviews, which helped us to gather beneficial information to continue with our project. On the other hand, we have established our strategies so that our proposal seems as real as possible, since we have analyzed and implemented our operations plan, commercial plan, our marketing plan and the organizational distribution for a period of 5 years, in which all the competent and organizational aspects that involve the implementation process of the present project are detailed. Finally, a Financial Business Plan was made, which showed that through financial indicators the viability of the project, therefore it was concluded that the present business model is profitable. / Trabajo de investigación

This thesis explores the politics of biosecurity and the governance of dual-use research. It focuses on life sciences, whose rapid development brings together the issues of biological weapons, terrorism, and the dangers of scientific innovations. The thesis has three goals: first, to situate the dilemma of dual-use research historically and conceptually, second, to analyse how the attempts to govern biosecurity and regulate dual-use research in life sciences affect the relations between science and security, and third, to discuss what implications this science-security nexus has for the politics of (in)security. Approaching the subject from critical security studies, the thesis looks at how the nexus between science and security is constructed. It does so, first, by exploring the dominant political and expert discourses on biosecurity and by looking at two distinct empirical sites, which exemplify how a regime of biosecurity governance evolves at a boundary of science and security in a 'global' and 'local' context: the international biological weapons regime and the Czech system of biosecurity management. The thesis finds that the attempts to govern dual-use research in life sciences focus not only on materials and technologies but also on scientific knowledge. It conceptualizes dual-use as a problem of...

Antimicrobial resistance is a major global health challenge. It threatens the achievement of multiple SDGs with disproportionately negative consequences for LMICs. AMR is associated with the misuse of antibiotics, which is especially dominant in livestock farming. On-farm biosecurity has been identified as an effective way to prevent diseases. This requires a change in the daily behaviours of farmers. While the application of social-psychological models gained immense popularity in veterinary and agricultural research, these models lack predictive and explanatory character, leading to the so-called intention-action gap. The emerging field of behavioural sciences likely offers a better explanation of human behaviour, however, studies published often lack use of an explicit theoretical framework. Therefore, this exploratory study aims to address this gap by using Kahneman’s Dual-Process Theory as a theoretical framework for behaviour science studies. To this end, a qualitative study with 15 smallholder poultry farmers in rural Ghana was conducted. The findings suggested the presence of cognitive biases and heuristics that hinder farmers’ uptake of biosecurity measures, such as temporal discounting, social cues, cognitive overload, psychological inertia and habits. However, all factors must be considered, including knowledge gaps, as well as practical and economic constraints. It is clear from the study that farmers are not a homogenous group and that any promotion of biosecurity is destined to fail if they do not take farmers' psychological and contextual reality into consideration. Therefore, this thesis concludes that additional insights and hypotheses can be generated using behavioural science and that it offers a better and more holistic theoretical framework than currently used behavioural change models. Suggestions for further work include more empirical study in farmer decision-making related to on-farm biosecurity from a behavioural lens. Specifically, the use of quantitative and experimental methods to investigate and confirm the hypotheses that emerged from this study.

El presente proyecto trata del análisis de factibilidad para el establecimiento de una empresa de fabricación de indumentaria de seguridad e higiene de uso hospitalario, considerando una proyección de 5 años. Nuestra marca “HIDMED”, por sus siglas en inglés High Indumentary Design, expresa la alta calidad y el diseño que brindaremos con la indumentaria que produciremos. Los productos estarán dirigidos al sector salud, siendo nuestros clientes potenciales: Hospitales MINSA, ESSALUD, Centros Médicos y Clínicas Privadas de Lima y Callao, los cuales serán elaborados en tela no tejida de polipropileno con ligas en el borde para un buen ajuste y cobertura total que evita el contacto con el producto, su diseño impide la transferencia de agentes contaminantes físicos brindando seguridad, bienestar y comodidad al personal de salud. Estos son toca tipo tira y mascarilla plana. La oportunidad de negocio se basa luego de observar la escasez y barreras comerciales para estos productos en el país además del crecimiento de este mercado en los próximos años, otros factores a evaluar son el incremento de centros asistenciales tanto públicos como privados y varios factores micro y macro económicos los cuales nos indican que el crecimiento de la economía en el Perú nos brinda un entorno adecuado para la realización de este proyecto. Nuestra estrategia será de diferenciación al ofrecer ambos productos de mayor calidad acordes al mercado local que actualmente la competencia importa los productos en baja resistencia y calidad. / The present project deals with the feasibility analysis for the establishment of a company for the manufacture of safety and hygiene clothing for hospital use, considering a projection of 5 years. Our brand "HIDMED", for its acronym in English High Indumentary Design, expresses the high quality and design that we provide with the clothing that we will produce. The products will be directed to the health sector, being our potential clients: Hospitals MINSA, ESSALUD, Medical Centers and Private Clinics of Lima and Callao, which will be made of non-woven polypropylene fabric with garters on the edge for a good fit and full coverage that avoids contact with the product, its design prevents the transfer of physical contaminants providing safety, well-being and comfort to health personnel. These are Tap type strip and Flat mask. The business opportunity is based on observing the scarcity and trade barriers for these products in the country as well as the growth of this market in the coming years, other factors to be evaluated are the increase of both public and private assistance centers and several micro and economic macro which indicate that the growth of the economy in Perú gives us an adequate environment for the realization of this project. Our strategy will be of differentiation by offering both products of higher quality according to the local market that currently the competition imports the products in low resistance and quality. / Trabajo de investigación

As keeping backyard poultry rises, human contact with zoonotic pathogens will increase. One such pathogen that backyard enthusiasts have exposure risks to is Salmonella spp. which may cause a potential public health threat due to its increasing multidrug resistancy. Salmonella spp. were present in 33 of 50 samples collected from 29 sites with backyard poultry coops in San Luis Obispo County during March to May in 2014. Two different Hardy-CHROME™ Salmonella Selective Media plates were used to culture and isolate positive samples of Salmonella spp.. Each positive isolate was tested for antimicrobial sensitivity to 6 standard antibiotics: Ampicillin, Bacitracin, Erythromycin, Gentamicin, Penicillin, and Tetracycline, at the standard disk concentration levels. The Kirby-Bauer antimicrobial sensitivity test determined that 12 different profiles emerged from the Salmonella spp. isolates. All antimicrobial sensitivity profiles showed multidrug resistance in vitro with only high susceptibility to 2 major antibiotics, Gentamicin at 97% and Ampicillin at 51%. All profiles were resistant to 1 or more of the antimicrobials tested, plus the control. One Salmonella isolated was resistant to all 6 antimicrobials and another isolate to 5. The Salmonella spp. isolates proved multidrug resistance between 73%-100% to the other 4 antibiotics tested. The 24 Salmonella spp. positive sites displayed a lack of proper biosecurity and poultry husbandry practices. The criteria developed for accessing the poultry’s environment ranged from dedicated shoes for cleaning, egg handling, access to other animals and wildlife, number of birds and breeds or species in a coop, cleaning routine, over-all biosecurity and human interactions. Human exposure to Salmonella spp. pathogenic strains could increase due to environmental cross contamination and deficiencies in sanitation. The presence of Salmonella spp. with a diversity of antibiotic resistance serotypes is an important source of zoonotic pathogens for animal and human diseases that has public health risk implications.

<p>Biological invasion is a major and growing threat to global biodiversity and human well-being, but research on the impacts of invaders on their recipient environments lags behind that on the mechanisms driving invader establishment and spread. The total impact of an invader is defined by its range size, abundance per unit area, and per-capita effect, with both per-capita effects and abundance varying over time and across the invader’s range. These context-dependencies are determined, in part, by functional differentiation between the invader and its recipient system. In this thesis, I investigate how functional differentiation between invaders and their recipient communities regulates the impact of plant invaders on community diversity and/or biomass production.</p> <p>First, I compare the effects of invasive Callery pear (<em>Pyrus calleryana</em> Decne.) to functionally similar native trees in three early-successional meadow environments in Indiana’s eastern corn belt plains. Despite my prediction that <em>P. calleryana</em> would have greater negative effects on the total biomass and diversity of the understory plant community compared to native trees, I found that <em>P. calleryana</em> had no significant impact on total cover, species richness, or Shannon’s or Simpson’s diversity indices for the understory community, compared to native <em>Liriodendron tulipifera</em> L., <em>Platanus occidentalis</em> L., or non-tree control plots. Likewise, <em>P. calleryana</em> had no significant impact on the native, introduced, woody, or native tree subsets of the understory community. These results indicate that the trait differences between <em>P. calleryana</em> and functionally similar native trees – and thus the per-invader effect of <em>P. calleryana</em> on its recipient community – are not of a great enough magnitude to produce changes in the understory community composition of these highly invaded, low diversity meadow environments with relatively new and sparse <em>P. calleryana</em> invasions. </p> <p>I then investigate the role of functional overlap in moderating invader impacts in California serpentine grassland communities through the lens of classic niche theory, which predicts that functional differentiation minimizes competition and therefore allows functionally distinct invaders to achieve higher establishment success but lower per-capita effects on their recipient communities. I tested this prediction by establishing small-scale experimental communities composed of individual or multiple functional groups differentiated by phenology – early-season annuals, nitrogen-fixing early-season annuals, and late-season annuals – and seeding these communities with early- or late-season invaders. I found that as invader density increased, effects on resident community biomass depended on complex patterns of invader and resident functional overlap. Across all resident community functional groups, the high density of early-season invaders enables them to capture a greater portion of total community biomass than late-season invaders, but early-season invaders reduce the ratio of resident:total invader biomass production by less, per-unit-biomass, than late-season invaders. These results highlight the need to consider both niche and fitness differences in predicting invader impacts and the complex nature of resident-invader interactions, which may not be sufficiently captured by coarse functional groups.</p>