Climate Dynamics, Invader Fitness, and Ecosystem Resistance in an Invasion-Factor Framework

As researchers and land managers increasingly seek to understand plant invasions and the external (climate) and internal (plant genetics) conditions that govern the process, new insight is helping to answer the elusive question of what makes some invasions successful and others not. Plant invasion success or failure is based on a combination of evolutionary and ecological processes. Abiotic (e.g., climate) and biotic (e.g., plant competition) conditions in the environment and plant genetics (e.g., fitness) combine in either decreasing or increasing invasion, yet it has proven challenging to know exactly which of these conditions leads to success for a given species, even when a wealth of empirical data is available. Further, current regional distribution models for invasive plant species rarely consider biotic and fitness interactions, instead focusing primarily on abiotic conditions. The crucial role of all three factors (climate dynamics, invader fitness, and ecosystem resistance) must not be ignored. Here we construct a three-factor invasion framework from which we develop conceptual models using empirical studies for yellow starthistle, nonnative common reed, and musk thistle, three dissimilar but commonly occurring invasive plant species in North America. We identify how components of the invasion process—rapid population increase, established local dominance, and rapid range expansion—are influenced by ecosystem resistance, invader fitness, and/or climate dynamics, a set of broadly defined factors for each of the three invasive plant species. Our framework can be used to (1) establish research priorities, (2) address gaps in theoretical understanding, and (3) identify invasion process components that can be targeted to improve management. Building on previous models, our unifying framework, which can be used for assessing any invasive plant species having sufficient empirical data, simultaneously shows the influence of ecosystem resistance, invader fitness, and climate dynamics factors on the invasion process. Nomenclature: Common reed, Phragmites australis (Cav.) Trin. ex Steud.; musk thistle, Carduus nutans L.; yellow starthistle, Centaurea solstitialis L

Frequency variation in site response as observed from strong motion data of the L’Aquila (2009) seismic sequence

Previous works based mainly on strong-motion recordings of large Japanese earthquakes showed that site amplification and soil fundamental frequency could vary over long and short time scales. These phenomena were attributed to non-linear soil behaviour: the starting fundamental frequency and amplification were both instantaneously decreasing and then recovering for a time varying from few seconds to several months. The recent April 6, 2009 earthquake (M W 6.3), occurred in the L’Aquila district (central Italy), gave us the possibility to test hypotheses on time variation of amplification function and soil fundamental frequency, thanks to the recordings provided by a pre-existing strong-motion array and by a large number of temporary stations. We investigated the intra- and inter-event soil frequency variations through different spectral analyses, including time-frequency spectral ratios and S-Transform (Stockwell et al. in IEEE Trans Signal Process 44:998–1001, 1996). Finally, analyses on noise recordings were performed, in order to study the soil behaviour in linear conditions. The results provided puzzling evidences. Concerning the long time scale, little variation was observed at the permanent stations of the Aterno Valley array. As for the short time-scale variation, the evidence was often contrasting, with some station showing a time-varying behavior, while others did not change their frequency with respect to the one evaluated from noise measurements. Even when a time-varying fundamental frequency was observed, it was difficult to attribute it to a classical, softening non-linear behaviour. Even for the strongest recorded shocks, with peak ground acceleration reaching 0.7 g, variations in frequency and amplitude seems not relevant from building design standpoint. The only exception seems to be the site named AQV, where the analyses evidence a fundamental frequency of the soil shifting from 3 Hz to about 1.5 Hz during the mainshock

Exploring Possibilities of Predicting Positive Counselor Qualities in Counseling Students from Personality Domains

In this pilot study, the authors investigated the degree that Big Five personality domains may predict the positive counselor qualities among 160 students enrolled in sections of a combined undergraduate/graduate Counseling Skills course. Positive counselor qualities of focus in this study are empathy, mindfulness or self-awareness, and unconditional positive self-regard in students studying counseling skills. The results do not suggest a significant predictive role for the Big Five personality domains for the Counseling Skills students, except that the Big Five domain of neuroticism predicted enough variation in mindfulness and unconditional positive self-regard to be practically significant. Limitations and potential implications of these findings for counselor educators and for future research are discussed

Frequency variation in site response over long and short time scales, as observed from strong motion data of the L’Aquila (2009) seismic sequence

Previous works based mainly on strong-motion recordings of large Japanese earthquakes showed that site amplification and soil fundamental frequency could vary over long and short time scales. These phenomena were attributed to non-linear soil behaviour due to inelastic, softening non-linearity: the starting fundamental frequency and amplification were both decreasing and not recovering for a time varying from few hours to several months. The recent April 6th 2009 earthquake (MW 6.3), occurred in the L'Aquila district (central Italy), gave us the possibility to test hypotheses on time variation of amplification function and soil fundamental frequency, thanks to the recordings provided by a preexisting strong-motion array and by a large number of temporary stations. We performed spectral ratio studies for the permanent stations of the Aterno Valley array where a reference station was available. The temporary stations and permanent ones were studied using time-frequency analyses through the S-Transform approach (Stockwell et al., 1996). Finally, analyses on noise recordings were performed, in order to study the soil behaviour in linear conditions. The results provided puzzling evidences. Concerning the long time scale, little variation was observed at the permanent stations of the Aterno Valley array. As for the short time-scale variation, the evidence was often contrasting, with some station showing a time-varying behavior, while others did not change their frequency with respect to the one evaluated from noise HVSR. Even when a time-varying fundamental frequency was observed, it was difficult to attribute it to a classical, softening non-linear behaviour. Even for the strongest recorded shocks, with PGA reaching 0.7 g, variations in frequency and amplitude seems not relevant from building design standpoint. The only exception seems to be the site named AQV, where the analyses evidence a fundamental frequency of the soil, shifting from 3 Hz to about 1.5 Hz during the mainshock

Manage Weeds on Your Farm: A Guide to Ecological Strategies

Manage Weeds on Your Farm is a definitive guide to understanding agricultural weeds and how to manage them efficiently, effectively and ecologically—for organic and conventional farmers alike. With the growing spread of herbicide-resistant weeds and with the public’s embrace of sustainably raised foods, farmers everywhere, both organic and conventional, are seeking better ways to eliminate or reduce their use of synthetic herbicides. The ecological approach to weed management seeks to first understand the biology and behavior of problem weeds and then to develop an integrated set of control strategies that exploit their weaknesses. Manage Weeds on Your Farm: A Guide to Ecological Strategies provides you with in-depth information about dozens of agricultural weeds found throughout the country and the best ways of managing them. In Part One, the book begins with a general discussion of weeds: their biology, behavior and the characteristics that influence how to best control their populations. It then describes the strengths and limitations of the most common cultural management practices, physical practices and cultivation tools. Part Two is a reference section that describes the identification, ecology and management of 63 of the most common and difficult-to-control weed species found in the United States. Ecological weed management is knowledge intensive, rather than input intensive. But it doesn’t have to be excessively labor intensive. Manage Weeds on Your Farm shows you how to outsmart your weeds by identifying the right tactic for the right weed at the right time, which will reduce as much as possible the labor required, while ensuring your weeds don’t impact crop yields. Note: Manage Weeds on Your Farm is focused on the weeds of arable cropping systems. It does not discuss the management of weeds in forests, turf, permanent pastures or perennial bioenergy crops. Weed management issues in forage production are discussed to some extent since forages are often rotated with other crops

Reduction in weed seedling emergence by pathogens following the incorporation of green crop residue

Summary Because tillage promotes the germination of many weed species and freshly killed plant material favours the growth of microbial pathogens, we hypothesised that the incorporation of green crop residue should temporarily reduce weed seedling emergence relative to unamended soil. Soil with field-incorporated green crop residue was compared with non-amended soil in glasshouse experiments by sowing several weed species at different times after incorporation. Species included Abutilon theophrasti, Chenopodium album, Amaranthus powellii, Setaria faberi, Echinochloa crus-galli and, in one year, lettuce and red clover. Soils with green crop residue reduced seedling emergence for 0-4 days after incorporation by an average of 30%. Comparison of emergence in nonsterilised soil with that in sterilised soil, with and without fresh crop residue, indicated that a biological agent caused the depressed emergence. In the third year of the study, the fungi Fusarium oxysporum and F. chlamydosporum were isolated from seeds exposed to soil amended with green crop residues, and their pathogenicity to seeds and seedlings was confirmed in bioassays. This study indicated that incorporation of fresh crop residue reduces the first flush of weed seedlings following tillage and that this depression in emergence is probably caused by pathogen attack on seeds and seedlings before emergence

Has VZV epidemiology changed in Italy? Results of a seroprevalence study

The aim of the study was to evaluate if and how varicella prevalence has changed in Italy. In particular a seroprevalence study was performed, comparing it to similar surveys conducted in pre-immunization era. During 2013–2014, sera obtained from blood samples taken for diagnostic purposes or routine investigations were collected in collaboration with at least one laboratory/center for each region, following the approval of the Ethics Committee. Data were stratified by sex and age. All samples were processed in a national reference laboratory by an immunoassay with high sensitivity and specificity. Statutory notifications, national hospital discharge database and mortality data related to VZV infection were analyzed as well. A total of 3707 sera were collected and tested. In the studied period both incidence and hospitalization rates decreased and about 5 deaths per year have been registered. The seroprevalence decreased in the first year of life in subjects passively protected by their mother, followed by an increase in the following age classes. The overall antibody prevalence was 84%. The comparison with surveys conducted with the same methodology in 1996–1997 and 2003–2004 showed significant differences in age groups 1–19 y. The study confirms that in Italy VZV infection typically occurs in children. The impact of varicella on Italian population is changing. The comparison between studies performed in different periods shows a significant increase of seropositivity in age class 1–4 years, expression of vaccine interventions already adopted in some regions

Identification of genes important for cutaneous function revealed by a large scale reverse genetic screen in the mouse.

The skin is a highly regenerative organ which plays critical roles in protecting the body and sensing its environment. Consequently, morbidity and mortality associated with skin defects represent a significant health issue. To identify genes important in skin development and homeostasis, we have applied a high throughput, multi-parameter phenotype screen to the conditional targeted mutant mice generated by the Wellcome Trust Sanger Institute's Mouse Genetics Project (Sanger-MGP). A total of 562 different mouse lines were subjected to a variety of tests assessing cutaneous expression, macroscopic clinical disease, histological change, hair follicle cycling, and aberrant marker expression. Cutaneous lesions were associated with mutations in 23 different genes. Many of these were not previously associated with skin disease in the organ (Mysm1, Vangl1, Trpc4ap, Nom1, Sparc, Farp2, and Prkab1), while others were ascribed new cutaneous functions on the basis of the screening approach (Krt76, Lrig1, Myo5a, Nsun2, and Nf1). The integration of these skin specific screening protocols into the Sanger-MGP primary phenotyping pipelines marks the largest reported reverse genetic screen undertaken in any organ and defines approaches to maximise the productivity of future projects of this nature, while flagging genes for further characterisation

Why does fertilization reduce plant species diversity? Testing three competition-based hypotheses

1 Plant species diversity drops when fertilizer is added or productivity increases. To explain this, the total competition hypothesis predicts that competition above ground and below ground both become more important, leading to more competitive exclusion, whereas the light competition hypothesis predicts that a shift from below-ground to above-ground competition has a similar effect. The density hypothesis predicts that more above-ground competition leads to mortality of small individuals of all species, and thus a random loss of species from plots. 2 Fertilizer was added to old field plots to manipulate both below-ground and above-ground resources, while shadecloth was used to manipulate above-ground resources alone in tests of these hypotheses. 3 Fertilizer decreased both ramet density and species diversity, and the effect remained significant when density was added as a covariate. Density effects explained only a small part of the drop in diversity with fertilizer. 4 Shadecloth and fertilizer reduced light by the same amount, but only fertilizer reduced diversity. Light alone did not control diversity, as the light competition hypothesis would have predicted, but the combination of above-ground and below-ground competition caused competitive exclusion, consistent with the total competition hypothesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75695/1/j.1365-2745.2001.00662.x.pd

Modeling the emergence of North African knapweed (Centaurea diluta), an increasingly troublesome weed in Spain

10 Pág.North African knapweed (Centaurea diluta Aiton) is an annual weed that is widespread in southern Spain and is of increasing concern in dryland cropping systems. Despite its expanding range in Spain, there is limited information on the emergence timing and pattern of this species, knowledge of which is critical for developing more timely and effective management strategies. Therefore, there is a need to develop simple and reliable models to predict the timing and emergence of this annual weed under dryland conditions. A multi-location field experiment was established across Spain in 2016 to 2017 to assess the emergence of C. diluta. At each of 11 locations, seeds were sown in the fall, and emergence was recorded. Overall emergence averaged 39% in the first year across all sites and 11% in the second year. In both years, the main emergence flush occurred at the beginning of the growing season. A three-parameter Weibull function best described seedling emergence of C. diluta. Emergence models were developed based on thermal time (TT) and hydrothermal time (HTT) and showed high predictability, as evidenced by root mean-square error prediction values of 10.8 and 10.7, respectively. Three cardinal points were established for TT and HHT at 0.5, 10, and 35 C for base, optimal, and ceiling temperatures, respectively, while base water potential was estimated at-0.5 MPa.We would like to thank Cátedra Adama and the Spanish Weed Science Society (SEMh) for providing financial support for this project. We are grateful to the many students and technicians who assisted with fieldwork at the different experimental locations. We would like to thank the Spanish government for partial funding, through project AVA 2019.020 “Advances in Technological Research in Winter Cereals: Genetic Improvement and Sustainable Management,” financed with Fondo Europeo de Desarrollo Regional (FEDER) funds (80%). Also, JT acknowledges support from the Spanish Ministry of Science, Innovation and Universities (grant Ramon y Cajal RYC2018-023866-I). We thank Enrique Chamber for installing and maintaining the data loggers at the various locations. No conflicts of interest have been declared.Peer reviewe