Avian diversity and abundance in three different vegetative landscapes around a shade-grown coffee plantation on Mount Totumas, Chiriquí Highlands, Panamá

Agricultura sostenible, como la agroforestería de café, tiene el potencial de conservar la biodiversidad local de muchos taxones. A pesar de los servicios beneficiosos como el control de plagas y la polinización que las aves pueden proporcionar, el grado en que el café sombrado promueva la biodiversidad de aves aún no se ha analizado completamente. El propósito de esta investigación fue para determinar si la biodiversidad y la abundancia de aves varían en áreas con diferente cobertura de vegetación y sombra alrededor de un cafetal de sombra. Se realizaron análisis vegetativos y se registraron las abundancias de las especies durante los conteos de puntos fijos en 3 sitios (no sombreado, sombreado, y bosque) alrededor del cafetal Mount Totumas de 3-hectares. Aunque la mayoría de las características vegetativas fueron significativamente diferentes entre cada sitio, los índices de diversidad de Simpson no lo fueron. Las especies observadas durante todo el período de estudio demuestran la capacidad de los sistemas agroforestales de café para apoyar especies migratorias, endémicas y algunas especies amenazadas o vulnerables. Este estudio indica el potencial de pequeños sistemas de agroforesterías sombreadas para conservar las especies de aves del hábitat boscoso. Esta investigación contribuye a otras encuestas de diversidad de aves en las tierras altas de Chiriquí y a encuestas de diversidad en otros sistemas agroforestales de pequeños agricultores en los trópicos. / Sustainable agriculture practices, such as coffee agroforestry, have the potential to conserve local biodiversity of numerous taxa. Considering the beneficial services of pest control and pollination which birds can provide, the extent to which shade-grown coffee directly promotes avian biodiversity has yet to be holistically analyzed. The purpose of this study was to determine if avian biodiversity and abundance are different in areas with different vegetation and shade cover around a shade-grown coffee plantation. Vegetative analyses were conducted, and species abundances were recorded during fixed point-counts at 3 sites (non-shaded, shaded, and forest) around the 3-hectare Mount Totumas coffee farm. Although most vegetative characteristics were significantly different between each site, Simpson’s diversity indices were not. Bird species observed over the entire study period demonstrate the ability of coffee agroforestry systems to support migratory, endemic, and some near-threatened or vulnerable species. This study indicates the potential for small shade-agroforestry systems to support the conservation of avian species from surrounding forest habitat and contributes to other avian diversity surveys in the Chiriquí Highlands and on smallholder farms

Ecological Drivers of Local Adaptation in White Clover: Herbivores or Winter Temperatures?

From the Washington University Office of Undergraduate Research Digest (WUURD), Vol. 13, 05-01-2018. Published by the Office of Undergraduate Research. Joy Zalis Kiefer, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Lindsey Paunovich, Editor; Helen Human, Programs Manager and Assistant Dean in the College of Arts and Sciences Mentor(s): Sara Wrigh

The Relative Effects of Functional Diversity and Structural Complexity on Carbon Dynamics in Late-Successional, Northeastern Mixed Hardwood Forests

Late-successional forests provide a unique opportunity to explore adaptive management approaches that mitigate atmospheric carbon dioxide levels through carbon storage while also enhancing ecological resilience to novel climate and disturbances. Typical benchmarks for adaptive forest management include species diversity and structural complexity, which are widely considered to increase ecosystem stability and productivity. However, the role of functional trait diversity (e.g., variation in leaf and stem traits) in driving forest productivity and ecosystem resilience remains underexplored. We leveraged existing continuous forest inventory (CFI) data and collected local functional trait observations from CFI plots within late-successional forests in western Massachusetts to explore links between aboveground carbon storage and different types of forest diversity. We then fit a linear model within a Bayesian hierarchical framework applying functional diversity, species diversity, and structural complexity as predictors of live aboveground biomass (AGB) within CFI plots. Our framework integrates local functional trait information with database species mean trait values using a multivariate structure to account for inherent trait syndromes and estimate functional diversity in each plot. Across 626 plot-timepoints, we found that integrating individual functional trait information from co-located plots yielded the best predictions of live AGB. Contrary to expectations, functional diversity had a negative relationship with live AGB. Whereas plots with low functional diversity and higher AGB were dominated by mid-to-late successional hardwood species, plots with high functional diversity had more shade-intolerant species and lower AGB mediated by recent small-scale disturbances. Our results reveal an ontogenetic shift in the effects of functional diversity on AGB productivity over the course of succession in northeastern temperate forests. Corroborating with classical models of biomass development in late-successional northern hardwood forests, our findings support the need for adaptive forest carbon management to facilitate a mosaic of different forest successional stages across the landscape to maximize live aboveground carbon benefits in northeastern mixed hardwood forests

Control of Metal-Release and Tuberculation in a Silica-Laden Groundwater Distribution System on the Volcanic Island of Lana\u27i

A corrosion control study for two distinct water distribution systems (WDS) has been completed for the Pulama Lana\u27i Water Company (Pulama). This project evaluated the use of chemical inhibitors to control corrosion and tuberculation within the Manele Bay WDS and the Lana\u27i City WDS. Pulama provides water to a population of 3,100 residents and is considering incorporating alternative water supplies in the future. Hence, knowing baseline corrosion rates within the WDS was desired. Several groundwater wells feed each of the WDS\u27s; however, water quality between wells varies. Well water supplied to the WDS\u27s is generally of high quality, therefore, the historical treatment method has been limited to disinfection prior to distribution. The distribution system consists of several materials of construction, which includes galvanized iron. Valves and pipes within the WDS were experiencing visible corrosion and tuberculation believed to be responsible for variable pressure drop throughout portions of the system. In this work, two corrosion racks, each consisting of two parallel loops, were designed, constructed, and installed at each site. One loop was maintained as a control while the other loop was used for testing alternative corrosion inhibitors. The racks utilized metal sample coupons and linear polarization resistance probes to provide data on corrosion rates of selected metals of interest. Results indicated that the water in Manele Bay experienced no noticeable change between the test loop and control loop when a corrosion inhibitor was added. A first experiment found the corrosion rates reached baseline steady—state at 4,000 operational hours. A second experiment found that the corrosion rates reached baseline steady—state at 2,200 operational hours. During these two experiments, the addition of a phosphate or silica—based inhibitor neither reduced nor increased the corrosion rates of mild steel, lead, and copper. Results from Lana\u27i City indicated that inhibitors offered little to no positive effect between the control condition and the test condition. During the first experiment, baseline corrosion was reached after 2,400 hours. The addition of a phosphate inhibitor did not reduce nor increase the corrosion rates of mild steel and lead. However, the corrosion rate of copper increased to 1.0mpy from 0.22mpy. The corrosion rate remained elevated after inhibitor feed was terminated. The second experiment reached baseline corrosion rates at 1,400 operational hours. The use of silica inhibitor neither reduced nor increased the corrosion rate of mil steel, lead, and copper. Since corrosion inhibitors were found to be ineffective, a valve exercise and replacement program for Pulama\u27s assets was recommended. This program included: (1) developing a detailed asset inventory, (2) implementing operation and maintenance tasks, (3) forming a valve replacement plan, and (4) establishing long range financial planning. An opinion of probable replacement cost for 200 new valves was conceptually estimated to approximate 3.3 million dollars expended over a 20 year time frame

COVID-19 Renters and Housing Instability: Combatting the Eviction Epidemic during the COVID-19 Pandemic in Knox County, Tennessee

COVID-19 has exacerbated preexisting inequities in Knox County, Tennessee. The disruption to employment caused by the pandemic has imposed a great financial burden for many individuals who rent housing. The primary relief that was afforded to renters during the pandemic was enabled by a federal eviction moratorium order, where covered renters could defer payments to avoid eviction while the moratorium was in effect. Some additional rental assistance was provided to local governments through the federal CARES Act pandemic relief package. Despite these provisions, many people experienced housing crises in Knox County, where over 3,000 renters have faced eviction filing from March 2020 – April 2022. The COVID-19 health crisis has emphasized flaws in the United States’ racial capitalist system and intensified socioeconomic inequalities as renters have been neglected and those with the means to own property have been protected. The constantly looming threat of not only contracting a deadly virus, but also being (re)submerged into the process of eviction burdens renters. In Knox County, Statewide Organizing for Community eMpowerment (SOCM) acted to pave pathways towards housing justice working on anti-eviction efforts during COVID-19, disseminating information to tenants facing the threat of eviction and supporting them throughout the eviction process. The project examines the multi-layered rental housing and displacement landscape from many perspectives and current and potential pathways towards a more just housing system. Using mixed-methods, I attempt to capture and analyze the many perspectives of those burdened by eviction and those involved in anti-eviction infrastructure in Knox County, Tennessee using community geographies and housing justice methods

Three Essays on Inequality and Political Economy

This thesis consists of three essays in the areas of political economy and applied microeconomics, covering housing, inequality, and public sector pensions. Once economies of scale are allowed into the production function, income distribution is no longer necessarily independent of efficiency in a general equilibrium framework. Chapter 2 analyzes a three-good, three-class general equilibrium model where external economies of scale exist on goods consumed primarily by the middleclass, and households have a preference for variety. In the case where the capital-labor ratio is the same across all goods, a transfer from a wealthy home to several poor homes increases consumption by the remaining citizens. Furthermore, if economies of scale are not too small, there exists a transfer from rich to middle-class households that is Pareto-optimal. Finally, the chapter demonstrates that a proportional increase in the size of the economy can offer the same benefits as redistribution. Cities around the world are experiencing a period of rising house prices and slow development, which is often attributed to increased development regulation. In Chapter 3 I develop a model of the housing market that incorporates congestion, and show that homeowners prefer to restrict housing supply more than renters. I test this model using 40 years of census data from two Australian cities. I demonstrate that public support for regulation can be traced back to homeowners, who seek to restrict supply below market levels in order to elevate the price of their assets and reduce local crowding externalities. I find that a 10 percentage-point decrease in home ownership rates over our period would result in an increase of around 1.6 million dwellings in Sydney, enough to house 14% of the 2011 population on a two-person-per-dwelling basis. A move to a centralized governance structure for the whole city would eliminate this relationship. In addition, I find that regardless of governance structure the proportion of elderly residents is negatively correlated with growth while income is, if anything, positively correlated with growth. The present value of unfunded local government defined benefit pension liabilities has escalated since the 2008 financial crisis. Chapter 4 considers the arguments for and against switching local government pensions from defined benefit schemes to defined contribution schemes. I note that the relative generosity of government pension schemes compared with the private sector is not necessarily tied to the pension structure. Also, defined benefit pensions may sometimes be cheaper for employers than defined contribution plans, as they allow employers to pool risks that they must otherwise compensate their employees for bearing. I use propensity score matching to test the difference between total remuneration of county employees in Nebraska (def ined contribution) and Kansas (defined benefit). I find that there is little difference between the cost of the total package under either plan. Furthermore, any differences are not consistent in either magnitude or sign between different sub categories of employees, or over time. I therefore conclude that there is no strong financial reason to recommend either plan structure over the other