Boom‐bust dynamics in biological invasions: towards an improved application of the concept

Boom‐bust dynamics – the rise of a population to outbreak levels, followed by a dramatic decline – have been associated with biological invasions and offered as a reason not to manage troublesome invaders. However, boom‐bust dynamics rarely have been critically defined, analyzed, or interpreted. Here, we define boom‐bust dynamics and provide specific suggestions for improving the application of the boom‐bust concept. Boom‐bust dynamics can arise from many causes, some closely associated with invasions, but others occurring across a wide range of ecological settings, especially when environmental conditions are changing rapidly. As a result, it is difficult to infer cause or predict future trajectories merely by observing the dynamic. We use tests with simulated data to show that a common metric for detecting and describing boom‐bust dynamics, decline from an observed peak to a subsequent trough, tends to severely overestimate the frequency and severity of busts, and should be used cautiously if at all. We review and test other metrics that are better suited to describe boom‐bust dynamics. Understanding the frequency and importance of boom‐bust dynamics requires empirical studies of large, representative, long‐term data sets that use clear definitions of boom‐bust, appropriate analytical methods, and careful interpretations

Animales autóctonos de la República Argentina: un abordaje desde la tecnología y los niños

El gobierno nacional y los gobiernos provinciales están llevando a cabo varias propuestas direccionadas a incorporar el uso de TICs en los distintos niveles educativos. Algunas de ellas con más impacto que otras. Sin duda alguna, el Programa Conectar-Igualdad, orientado solamente al nivel secundario, es el más difundido y ha permitido que muchos alumnos secundarios obtengan sus netbooks y, con ello, muchos hogares cuenten con acceso a computadoras. Acompañando al Programa Conectar-Igualdad, en el nivel de educación primaria, existe un programa similar en la provincia de Buenos Aires de reciente implementación, que entregará a escuelas primarias un kit de netbooks que podrán ser usadas en la escuela. Dado que este programa recién se inicia, actualmente son muy pocos los establecimientos alcanzados por el mismo, y por lo tanto, aún la mayoría de las escuelas primarias hoy cuentan con instalaciones informáticas desactualizadas y sin recursos humanos capaces de dar soporte en su uso y mantenimiento. Los niños y niñas hoy en día suelen tener acceso a mucha información sobre casi cualquier tema en Internet y, aunque para ellos el manejo de la computadora es intuitivo, su uso se focaliza por lo general, en jugar y comunicarse con amigos. Pocas veces se utiliza la computadora con el objetivo de aprender temas propios de la currícula escolar y, en menos casos, esto sucede dentro de la escuela. Este artículo presenta un proyecto llevado a cabo durante el segundo semestre del año 2012 en la Escuela Primaria N 12 de City Bell, provincia de Buenos Aires. Se muestra un caso de éxito en el uso de aplicaciones libres no tradicionales para acompañar y dar soporte a los temas abordados en el aula. En particular, se trabajó sobre el estudio de animales autóctonos de nuestro país con niños de primer año de escuela primaria. Los resultados obtenidos fueron muy satisfactorios, tanto desde el punto de vista de la actividad áulica llevada a cabo, como así también desde el aporte realizado por los niños al proyecto “Expandiendo la Comunidad de Software Libre en las Escuelas”.Eje: Tecnología en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

Animales autóctonos de la República Argentina: un abordaje desde la tecnología y los niños

El gobierno nacional y los gobiernos provinciales están llevando a cabo varias propuestas direccionadas a incorporar el uso de TICs en los distintos niveles educativos. Algunas de ellas con más impacto que otras. Sin duda alguna, el Programa Conectar-Igualdad, orientado solamente al nivel secundario, es el más difundido y ha permitido que muchos alumnos secundarios obtengan sus netbooks y, con ello, muchos hogares cuenten con acceso a computadoras. Acompañando al Programa Conectar-Igualdad, en el nivel de educación primaria, existe un programa similar en la provincia de Buenos Aires de reciente implementación, que entregará a escuelas primarias un kit de netbooks que podrán ser usadas en la escuela. Dado que este programa recién se inicia, actualmente son muy pocos los establecimientos alcanzados por el mismo, y por lo tanto, aún la mayoría de las escuelas primarias hoy cuentan con instalaciones informáticas desactualizadas y sin recursos humanos capaces de dar soporte en su uso y mantenimiento. Los niños y niñas hoy en día suelen tener acceso a mucha información sobre casi cualquier tema en Internet y, aunque para ellos el manejo de la computadora es intuitivo, su uso se focaliza por lo general, en jugar y comunicarse con amigos. Pocas veces se utiliza la computadora con el objetivo de aprender temas propios de la currícula escolar y, en menos casos, esto sucede dentro de la escuela. Este artículo presenta un proyecto llevado a cabo durante el segundo semestre del año 2012 en la Escuela Primaria N 12 de City Bell, provincia de Buenos Aires. Se muestra un caso de éxito en el uso de aplicaciones libres no tradicionales para acompañar y dar soporte a los temas abordados en el aula. En particular, se trabajó sobre el estudio de animales autóctonos de nuestro país con niños de primer año de escuela primaria. Los resultados obtenidos fueron muy satisfactorios, tanto desde el punto de vista de la actividad áulica llevada a cabo, como así también desde el aporte realizado por los niños al proyecto “Expandiendo la Comunidad de Software Libre en las Escuelas”.Eje: Tecnología en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

Global change, global trade, and the next wave of plant invasions

Copyright © 2012 Ecological Society of AmericaMany non-native plants in the US have become problematic invaders of native and managed ecosystems, but a new generation of invasive species may be at our doorstep. Here, we review trends in the horticultural trade and invasion patterns of previously introduced species and show that novel species introductions from emerging horticultural trade partners are likely to rapidly increase invasion risk. At the same time, climate change and water restrictions are increasing demand for new types of species adapted to warm and dry environments. This confluence of forces could expose the US to a range of new invasive species, including many from tropical and semiarid Africa as well as the Middle East. Risk assessment strategies have proven successful elsewhere at identifying and preventing invasions, although some modifications are needed to address emerging threats. Now is the time to implement horticulture import screening measures to prevent this new wave of plant invasions.National Science Foundatio

Will extreme climatic events facilitate biological invasions?

Copyright © 2012 Ecological Society of AmericaExtreme climatic events (ECEs) – such as unusual heat waves, hurricanes, floods, and droughts – can dramatically affect ecological and evolutionary processes, and these events are projected to become more frequent and more intense with ongoing climate change. However, the implications of ECEs for biological invasions remain poorly understood. Using concepts and empirical evidence from invasion ecology, we identify mechanisms by which ECEs may influence the invasion process, from initial introduction through establishment and spread. We summarize how ECEs can enhance invasions by promoting the transport of propagules into new regions, by decreasing the resistance of native communities to establishment, and also sometimes by putting existing non-native species at a competitive disadvantage. Finally, we outline priority research areas and management approaches for anticipating future risks of unwanted invasions following ECEs. Given predicted increases in both ECE occurrence and rates of species introductions around the globe during the coming decades, there is an urgent need to understand how these two processes interact to affect ecosystem composition and functioning.National Science Foundatio

Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?

Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community diversity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant diversity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring species’ relative abundance will more rapidly advance our understanding of invasions.This is the publisher’s final pdf. The published article is copyrighted by John Wiley & Sons Ltd and can be found at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2486

Understory Succession Following a Dieback of Myrica faya in Hawai'i Volcanoes National Park

Studies of invasion by the introduced nitrogen-fixing tree Myrica faya Aiton in Hawai'i Volcanoes National Park have led to predictions that the nitrogen-rich soil M faya creates will promote invasion by nonindigenous plant species. An insect-caused dieback of M. faya that began in the late 1980s provides an opportunity to test this hypothesis. We compared· percentage cover and density of all plant species under live and dead M. faya, as well as total nitrogen in soil and plant tissue. Mean percentage cover of four common species increased significantly, and no species decreased in cover after dieback. Cover of native shrubs and herbs increased from 4.8 to 15.2%, largely due to the spread of Carex wahuensis C.A. Mey, and introduced grasses increased from 2.3 to 14.1%. Density of native shrubs did not differ beneath live and dead M. faya, but immature introduced grass individuals were significantly more numerous beneath dead M. faya. We found no differences in total nitrogen in soil or plant tissue collected beneath live versus dead M. faya. Beneath dead M. faya, cover of C. wahuensis increased with total soil N, and introduced grass cover decreased. This surprising result may be the legacy of shading effects from the live M. faya canopies, for which total soil N may be an indicator. Success of grass seedlings compared with failure of native shrubs to recruit from seed suggests that dieback promotes nonnative grass species. Replacement of M. faya with introduced grasses may greatly increase fire risk

Data from: Structural, compositional and trait differences between native and non-native dominated grassland patches

1. Non-native species with growth forms that are different from the native flora may alter the physical structure of the area they invade, thereby changing the resources available to resident species. This in turn can select for species with traits suited for the new growing environment. 2. We used adjacent uninvaded and invaded grassland patches to evaluate whether the shift in dominance from a native perennial bunchgrass, Nassella pulchra, to the early season, non-native annual grass, Bromus diandrus, affects the physical structure, available light, plant community composition and community weighted trait means. 3. Our field surveys revealed that the exotic grass B. diandrus alters both the vertical and horizontal structure creating more dense continuous vegetative growth and dead plant biomass than patches dominated by N. pulchra. These differences in physical structure are responsible for a threefold reduction in available light and likely contribute to the lower diversity, especially of native forbs in B. diandrus dominated patches. Further, flowering time began earlier and seed size and plant height were higher in B. diandrus patches relative to N. pulchra patches. 4. Our results suggest that species that are better suited (taller, earlier phenology and larger seed size) for low light availability are those that coexist with B. diandrus and this is consistent with our hypothesis that change in physical structure with B. diandrus invasion is an important driver of community and trait composition. 5. The traits of species able to coexist with invaders are rarely considered when assessing community change following invasion, however this may be a powerful approach for predicting community change in environments with high anthropogenic pressures, such as disturbance and nutrient enrichment. It also provides a means for selecting species to introduce when trying to enhance native diversity in an otherwise invaded community

Molinari_Abundance Metric and Trait Data

This file includes trait data (SLA, peak timing of flowering, plant height, seed size and weight) for all grasslands species encountered in our surveys. SLA was collected by sampling plants from the field, while other traits were acquired using field guides (mainly the Jepson Manual of Higher Plants). The abundance metric was calculated as the difference between the species' abundance in native (Nassella pulchra) and exotic (Bromus diandrus) dominated grasslands