The relationship between community diversity and exotic plants: cause or consequence of invasion?

Invasion ecology has suffered from the artificial separation of invasibility and impact processes in understanding the ationship between diversity and plant invasion. By studying these independently functioning stages of invasion in concert, we can gain great insight into the biological causes and consequences of invasions, and develop crucial information for the generation of adequate management strategies. Our conceptual framework provides a structure to synthesize the current body of research, suggests research needed to fill the gaps in understanding and to organize results from future research. The framework is a powerful tool to guide ecological understanding of the relationship between invasion and diversity across systems, species, and scales. The case studies discussed here clearly show how both the cause and consequence of diversity may operate simultaneously hin an invasion to generate the community associations often noted in static studies. Currently, it is not possible to make generalizations about which mechanism is the most important because of the extreme lack of information for most plant invasions. To understand the nature of the relationship between diversity and invasion, both of these processes must be assessed to determine their relative contribution

Urban Principles for Ecological Landscape Design and Maintenance: Scientific Fundamentals

Urban ecology is a rapidly developing scientific discipline with great relevance to sustainable city design and management. Though several frameworks have been proposed in the last 10 years, urban ecology, as yet, has no complete, mature theory. There are, however, general principles emerging that may facilitate the development of such a theory. In the meantime, these principles can serve as useful guides for ecological landscape design and maintenance. This paper aims to use the principles to conceptually frame a series of papers to follow in this special issue. The main ecological principles concerning cities are that: 1) Cities are ecosystems; 2) Cities are spatially heterogeneous; 3) Cities are dynamic; 4) Human and natural processes interact in cities; and 5) Ecological processes are still at work and are important in cities. The first three principles address the structure of cities and the change in structure through time. The remaining two principles focus on ecological processes in cities. We briefly summarize each of these principles and their roots in the ecological and design fields. Each principle points to ecological functions that can be translated into ecosystem services. Application of these principles to ecological landscape design and maintenance is discussed

Frida Kahlo Cyborg: uma olhada na sua vida-obra

Due to the strong influence of coloniality of knowledge and the dominance of western Cartesian thought, Latin American thought has reproduced the dualisms surrounding the way in which we think about different dimensions of life: mind-body, nature-culture, natural-artificial. Nevertheless, alternatives that make the structure of dualistic thought tremble and that allow us to think about life from a different place have been proposed. It is in relation to the latter that we reflect about the life-work of Frida Kahlo, an artist who embodied and captured the conditions of  her time in her art: the MexicanRevolution and the militancy of the Latin American left in which she participates, characterised by a strong patriotism. Additionally, she explores the diseases and ailments that she goes through, and the multiple surgeries and rehabilitation procedures she has to undergo, hence the disabledbody acquires a leading role in her works. The aim of this essay is to question how the artist plays with the representations of the body, taking Donna Haraway’s idea of the cyborg as a starting point.  Throughout her work, Frida is and represents bodies that escape hegemony, that transgress andare formed in the ruptures of the binary oppositions of the colonial, patriarchal and western. In this way, Frida Kahlo’s life-work exhibits the microphysics of power as well, shedding light on the instability of the invented limits of technological reason as sovereign of the body and proposing newways of experiencing existence.El pensamiento latinoamericano, debido a las fuertes influencias de la colonialidad del saber y la dominación del pensamiento cartesiano occidental, hareproducido los dualismos en torno a pensar diferentes dimensiones de la vida: cuerpomente, naturaleza-cultura, naturalartificial. Sin embargo, se hanplanteado alternativas que sacuden las estructuras del pensamiento dualista, que permiten pensar la vida desde otro lugar. En relación con esto  reflexionamos sobre la vida-obra de Frida Kahlo (1907-1954), una artista que encarnó y reflejó en su arte las condiciones de su tiempo: la Revolución Mexicana y la militancia de la izquierda latinoamericana, caracterizada por un fuerte patriotismo, en la que participa. Asimismo, explora las enfermedades ydolencias que atraviesa, y lasmúltiples operaciones y procesos  de rehabilitación a los que debe someterse, por lo que el cuerpo discapacitado adquiere un lugar protagónico en su obra. El objetivo de este ensayo es problematizar cómo la artista juega con las representaciones del cuerpo, tomando como punto de partida la idea del cyborg de Donna Haraway. A lo largo de su obra, Frida es y representa cuerpos que se salen de la hegemonía, que transgreden y se forman en las rupturas de las oposiciones binarias de lo colonial, patriarcal y occidental. De este modo, la vida-obra de Frida exhibe también las microfísicas del poder, arrojando luz sobre la inestabilidad de los límites inventados de la razón tecnológica como soberana del cuerpo y proponiendo nuevas formas de experimentar la existencia.O pensamento latinoamericano, devido às fortes influências da colonialidade do saber e do domínio do pensamento cartesiano ocidental, tem reproduzido dualismos em torno do pensamento sobre diferentes dimensões da vida: corpo-mente, natureza-cultura, natural-artificial. No entanto, foram propostasalternativas que abalam as estruturas do pensamento dualista, que nos permitem pensar a vida a partir de outro lugar. A esse respeito, refletimos sobre a vida-obra de Frida Kahlo (1907-1954), artista que encarnou e manifestou em sua arte as condições de seu tempo: a Revolução Mexicana e a militânciada esquerda latinoamericana, caracterizada por um forte patriotismo, em que ela participa. Da mesma forma, explora as doenças e enfermidades pelas  quais passa, e as múltiplas operações e processos de reabilitação aos quais deve se submeter, pelo qual o corpo deficiente adquire um lugar de destaque em seu trabalho. O objetivo deste ensaio é problematizar como a artista joga com as representações do corpo, tomando como ponto de partida a ideia de Donna Haraway sobre o cyborg. Ao longo de sua obra, Frida é e representa corpos que rompem com a hegemonia, que transgridem e se formam nas rupturas das oposições binárias do colonial, patriarcal e ocidental. Dessa forma, a vidaobra de Frida também expõe a microfísica do poder, lançando luz sobre a instabilidade dos limites inventados pela razão tecnológica como soberana do corpo e propondo novas formas de experimentar a existência

The Benefits and Limits of Urban Tree Planting for Environmental and Human Health

Many of the world's major cities have implemented tree planting programs based on assumed environmental and social benefits of urban forests. Recent studies have increasingly tested these assumptions and provide empirical evidence for the contributions of tree planting programs, as well as their feasibility and limits, for solving or mitigating urban environmental and social issues. We propose that current evidence supports local cooling, stormwater absorption, and health benefits of urban trees for local residents. However, the potential for urban trees to appreciably mitigate greenhouse gas emissions and air pollution over a wide array of sites and environmental conditions is limited. Consequently, urban trees appear to be more promising for climate and pollution adaptation strategies than mitigation strategies. In large part, this is due to space constraints limiting the extent of urban tree canopies relative to the current magnitude of emissions. The most promising environmental and health impacts of urban trees are those that can be realized with well-stewarded tree planting and localized design interventions at site to municipal scales. Tree planting at these scales has documented benefits on local climate and health, which can be maximized through targeted site design followed by monitoring, adaptive management, and studies of long-term eco-evolutionary dynamics.Peer reviewe

Imaging Oxygen Distribution in Marine Sediments. The Importance of Bioturbation and Sediment Heterogeneity

The influence of sediment oxygen heterogeneity, due to bioturbation, on diffusive oxygen flux was investigated. Laboratory experiments were carried out with 3 macrobenthic species presenting different bioturbation behaviour patterns:the polychaetes Nereis diversicolor and Nereis virens, both constructing ventilated galleries in the sediment column, and the gastropod Cyclope neritea, a burrowing species which does not build any structure. Oxygen two-dimensional distribution in sediments was quantified by means of the optical planar optode technique. Diffusive oxygen fluxes (mean and integrated) and a variability index were calculated on the captured oxygen images. All species increased sediment oxygen heterogeneity compared to the controls without animals. This was particularly noticeable with the polychaetes because of the construction of more or less complex burrows. Integrated diffusive oxygen flux increased with oxygen heterogeneity due to the production of interface available for solute exchanges between overlying water and sediments. This work shows that sediment heterogeneity is an important feature of the control of oxygen exchanges at the sediment–water interface

Trees Grow on Money: Urban Tree Canopy Cover and Environmental Justice

This study examines the distributional equity of urban tree canopy (UTC) cover for Baltimore, MD, Los Angeles, CA, New York, NY, Philadelphia, PA, Raleigh, NC, Sacramento, CA, and Washington, D.C. using high spatial resolution land cover data and census data. Data are analyzed at the Census Block Group levels using Spearman\u27s correlation, ordinary least squares regression (OLS), and a spatial autoregressive model (SAR). Across all cities there is a strong positive correlation between UTC cover and median household income. Negative correlations between race and UTC cover exist in bivariate models for some cities, but they are generally not observed using multivariate regressions that include additional variables on income, education, and housing age. SAR models result in higher r-square values compared to the OLS models across all cities, suggesting that spatial autocorrelation is an important feature of our data. Similarities among cities can be found based on shared characteristics of climate, race/ethnicity, and size. Our findings suggest that a suite of variables, including income, contribute to the distribution of UTC cover. These findings can help target simultaneous strategies for UTC goals and environmental justice concerns

Why socio-political borders and boundaries matter in conservation.

Acting to demarcate the spatial limits of decision-making processes, socio-political boundaries are an inevitable part of a human-dominated world. Rarely coincident with ecological boundaries, and thus having no ecological functional role by themselves, they nevertheless impose substantial costs on biodiversity and ecosystem conservation by fragmenting ownership, governance, and management. Where boundaries are in place, a lack of coordination on either side of a boundary affects the efficiency and efficacy of ecosystem management. We suggest four research pathways which will enhance our ability to address the adverse effects of socio-political borders on conservation: (i) scale-matching, (ii) quantification of the mutual economic benefits of conservation across boundaries, (iii) determining transboundary societal values, and (iv) acknowledging the importance of stakeholder behaviour and incentives

Democratization of ecosystem services—a radical approach for assessing nature’s benefits in the face of urbanization

OBJECTIVES : (1) To evaluate how ecosystem services may be utilized to either reinforce or fracture the planning and development practices that emerged from segregation and economic exclusion; (2) To survey the current state of ecosystem service assessments and synthesize a growing number of recommendations from the literature for renovating ecosystem service analyses. METHODS : Utilizing current maps of ecosystem service distribution in Bushbuckridge Local Municipality, South Africa, we considered how a democratized process of assessing ecosystem services will produce a more nuanced representation of diverse values in society and capture heterogeneity in ecosystem structure and function. RESULTS : We propose interventions for assessing ecosystem services that are inclusive of a broad range of stakeholders’ values and result in actual quantification of social and ecological processes. We demonstrate how to operationalize a pluralistic framework for ecosystem service assessments. CONCLUSION : A democratized approach to ecosystem service assessments is a reimagined path to rescuing a poorly implemented concept and designing and managing future socialecological systems that benefit people and support ecosystem integrity. It is the responsibility of scientists who do ecosystem services research to embrace more complex, pluralistic frameworks so that sound and inclusive scientific information is utilized in decision-making.The National Science Foundation under Grant No. RCN 1140070.https://www.tandfonline.com/loi/tehs20am2019Educational Psycholog

Dynamics of N removal over annual time periods in a suburban river network

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): G03038, doi:10.1029/2007JG000660.River systems are dynamic, highly connected water transfer networks that integrate a wide range of physical and biological processes. We used a river network nitrogen (N) removal model with daily temporal resolution to evaluate how elevated N inputs, saturation of the denitrification and total nitrate removal processes, and hydrologic conditions interact to determine the amount, timing and distribution of N removal in the fifth-order river network of a suburban 400 km2 basin. Denitrification parameters were based on results from whole reach 15NO3 tracer additions. The model predicted that between 15 and 33% of dissolved inorganic nitrogen (DIN) inputs were denitrified annually by the river system. Removal approached 100% during low flow periods, even with the relatively low and saturating uptake velocities typical of surface water denitrification. Annual removal percentages were moderate because most N inputs occurred during high flow periods when hydraulic conditions and temperatures are less favorable for removal by channel processes. Nevertheless, the percentage of annual removal occurring during above average flow periods was similar to that during low flow periods. Predicted river network removal proportions are most sensitive to loading rates, spatial heterogeneity of inputs, and the form of the removal process equation during typical base flow conditions. However, comparison with observations indicates that removal by the river network is higher than predicted by the model at moderately high flows, suggesting additional removal processes are important at these times. Further increases in N input to the network will lead to disproportionate increases in N exports due to the limits imposed by process saturation.This work was funded by NSF-DEB- 0614282, NSF-OCE-9726921, NSF-DEB-0111410, and NSF-BCS- 0709685