A systematic review of arthropod community diversity in association with invasive plants

Invasive plants represent a significant financial burden for land managers and also have the potential to severely degrade ecosystems. Arthropods interact strongly with plants, relying on them for food, shelter, and as nurseries for their young. For these reasons, the impacts of plant invasions are likely strongly reflected by arthropod community dynamics including diversity and abundances. A systematic review was conducted to ascertain the state of the literature with respect to plant invaders and their associated arthropod communities. We found that the majority of studies did not biogeographically contrast arthropod community dynamics from both the home and away ranges and that studies were typically narrow in scope, focusing only on the herbivore feeding guild, rather than assessing two or more trophic levels. Importantly, relative arthropod richness was significantly reduced on invasive plant species. Phylogenetic differences between the invasive and local plant community as well as the plant functional group impact arthropod diversity patterns. A framework highlighting some interaction mechanisms between multiple arthropod trophic levels and native and invasive plants is discussed and future research directions relating to these interactions and the findings herein are proposed

Paléophytogéographie et paléoclimats postglaciaires dans l’ouest du Bas-Saint-Laurent, Québec

L'analyse pollinique des sédiments de quatre lacs du Bas-Saint-Laurent et de la Côte-du-Sud permet de retracer l'existence d'une phase initiale de toundra s'étendant sur une durée estimée à 500-1000 ans, après à la déglaciation. Cette toundra montre un développement progressif à partir d'un quasi-désert jusqu'à un stade arbustif à bouleau glanduleux, en passant par un stade herbacé riche en plantes arctiques-alpines dont la présence est confirmée par l'analyse macrofossile. L'accumulation organique dans les lacs ne survient que vers 9500-9200 BP, soit plus de 2000 ans après la déglaciation, et correspond à l'arrivée des premiers arbres, d'après les macrorestes. Le tardiglaciaire régional paraît donc avoir été climatiquement très rigoureux par rapport aux régions sises au sud-ouest et au sud, dans les Appalaches. Les forêts sont restées ouvertes jusque vers 8000 BP, constituées surtout de l'épinette noire, des peupliers, du mélèze et du bouleau blanc. La zone pollinique correspondante est dominée par l'aulne crispé, qui a dû jouer un rôle important dans le couvert végétal durant une période caractérisée par une forte incidence des feux. Par la suite, la végétation moderne s'est établie, soit une mosaïque de sapinières et d'érablières avec sensiblement les mêmes séquences physiographiques et les mêmes gradients phytogéographiques régionaux que ceux actuellement constatés dans ce secteur des Appalaches. Les cédrières tourbeuses et les sapinières humides à thuya répandues actuellement dans les basses terres estuariennes et à la marge nord du plateau appalachien ne se sont toutefois développées que vers 3600 ans avant l'actuel. L'Optimum climatique holocene n'est clairement marqué que par une plus grande abondance du pin blanc de 7000 à 3600 ans BP, notamment à la marge nord du plateau appalachien.Postglacial paleophytogeography and paleoclimates in the western part of the Lower Saint Lawrence River region, Québec. Pollen analysis of the sediments of four lakes in the Lower Saint Lawrence River region, north of Maine, shows that tundra vegetation existed during an estimated period of 500 to 1000 years following ice retreat. Progressive development of the tundra from a quasi-desert to a shrub stage with dwarf birch, through an herb stage rich in arctic-alpine taxa is confirmed by macrofossil analysis. Organic sedimentation in the lakes started only around 9500-9200 BP, that is to say more than 2000 years after ice retreat, and is coincident with the arrival of the first trees (macrofossils) in the area. The regional late-glacial climate was thus apparently very harsh, compared to the Appalachian regions located to the south and southwest. Black spruce, the poplars, larch and white birch comprised the forests which remained open until around 8000 BP. The corresponding pollen zone is dominated by green alder which played a major role in the plant cover during a period characterized by a great incidence of fire. Afterwards, the modern vegetation developed, corresponding to a mosaic of fir and maple communities with physiographic sequences and regional phytogeographic gradients similar to those present today within this section of the Appalachian range. Eastern white cedar, which nowadays occupies the wet or boggy sites of the estuarine lowlands and of the northern margin of the Appalachian plateau, whether in pure stands or with balsam fir, began to increase by 3600 BP. The Holocene Climatic Optimum is clearly marked in the study area only by a greater abundance of white pine, especially at the northern margin of the Appalachian plateau between 7000 abd 3600 BP.Mit der Pollenanalyse der Sedimente von vier Seen IaBt sich der Beginn einer Tundra-Phase nachweisen, die nach der Enteisung schâtzungsweise 500-1000 Jahre dauerte. Diese Tundra zeigt eine progressive Entwicklung, ausgehend von einer Quasi-wiiste bis hin zu einem Buschstadium mit Zwergbirke uber ein Pflanzenstadium, das reich an arktisch-alpinen Pflanzen war, deren Vorkommen durch die makrofossile Analyse bestàtigt wird. Die organische Sedimentierung in den Seen tritt erst gegen 9500-9200 Jahre v.u.Z. auf, d.h. uber 2000 Jahre nach Enteisung, und sie entspricht der Ankunft der ers-ten Baume, den Makroresten nach zu schlieBen. Das régionale Spâtglazial scheint demnach klimatisch sehr rauh gewesen zu sein im Vergleich zu den sudwestlich und sudlich gelegenen Gebieten in den Appa-lachen. Die Wàlder blieben bis gegen 8000 v.u.Z. offen und bestanden vor allem aus Schwarztanne, Pappel, Làrche und WeiB-birke. Das entsprechende Pollengebiet ist dominiert von Grunerle, welche eine wichtige RoIIe in der Pflanzendecke gespielt haben mu(3, in einer Zeit, in der gehâuft Brànde auftraten. In der Folgezeit hat sich die moderne Vegetation angesiedelt, d.h. ein Mosaik von Tannen- und Ahornwàldern. Indessen haben die torfhaltigen Zedernwàlder und die feuch-ten Thuja-Tannenwâlder, die gegenwartig in den Mundungs-Niederungen und am Nord-saum des Appalachenplateaus verbreitet sind, sich erst gegen 3600 v.u.Z. entwickelt. Das KIimatische Optimum im Holozan ist nur durch eine grôBere FuIIe der WeiBtanne von 7000 bis 3600 Jahre v.u.Z. klar gekennzeichnet

Age differences in voice evaluation : from auditory-perceptual evaluation to social interactions

Purpose: The factors that influence the evaluation of voice in adulthood, as well as the consequences of such evaluation on social interactions, are not well understood. Here, we examined the effect of listeners' age and the effect of talker age, sex, and smoking status on the auditory-perceptual evaluation of voice, voice-related psychosocial attributions, and perceived speech tempo. We also examined the voice dimensions affecting the propensity to engage in social interactions. Method: Twenty-five younger (age 19-37 years) and 25 older (age 51-74 years) healthy adults participated in this cross-sectional study. Their task was to evaluate the voice of 80 talkers. Results: Statistical analyses revealed limited effects of the age of the listener on voice evaluation. Specifically, older listeners provided relatively more favorable voice ratings than younger listeners, mainly in terms of roughness. In contrast, the age of the talker had a broader impact on voice evaluation, affecting auditory-perceptual evaluations, psychosocial attributions, and perceived speech tempo. Some of these talker differences were dependent upon the sex of the talker and his or her smoking status. Finally, the results also show that voice-related psychosocial attribution was more strongly associated with the propensity of the listener to engage in social interactions with a person than auditory-perceptual dimensions and perceived speech tempo, especially for the younger adults. Conclusions: These results suggest that age has a broad influence on voice evaluation, with a stronger impact for talker age compared with listener age. While voice-related psychosocial attributions may be an important determinant of social interactions, perceived voice quality and speech tempo appear to be less influential

Effects of age on the amplitude, frequency and perceived quality of voice

The manner and extent to which voice amplitude and frequency control mechanisms change with age is not well understood. The related question of whether the assessment of one’s own voice evolves with age, concomitant with the acoustical changes that the voice undergoes, also remains unanswered. In the present study, we characterized the aging of voice production mechanisms (amplitude, frequency), compared the aging voice in different experimental contexts (vowel utterance, connected speech) and examined the relationship between voice self-assessment and age-related voice acoustical changes. Eighty healthy adults (20 to 75 years old) participated in the study, which involved computation of several acoustical measures of voice (including measures of fundamental frequency, voice amplitude, and stability) as well as self-assessments of voice. Because depression is frequent in older adults, depression and anxiety scores were also measured. As was expected, analyses revealed age effects on most acoustical measures. However, there was no interaction between age and the ability to produce high/low voice amplitude/frequency, suggesting that voice amplitude and frequency control mechanisms are preserved in aging. Multiple mediation analyses demonstrated that the relationship between age and voice self-assessment was moderated by depression and anxiety scores. Taken together, these results reveal that while voice production undergoes important changes throughout aging, the ability to increase/decrease the amplitude and frequency of voice are preserved, at least within the age range studied, and that depression and anxiety scores have a stronger impact on perceived voice quality than acoustical changes themselves

Invasive Acer negundo outperforms native species in non-limiting resource environments due to its higher phenotypic plasticity

<p>Abstract</p> <p>Background</p> <p>To identify the determinants of invasiveness, comparisons of traits of invasive and native species are commonly performed. Invasiveness is generally linked to higher values of reproductive, physiological and growth-related traits of the invasives relative to the natives in the introduced range. Phenotypic plasticity of these traits has also been cited to increase the success of invasive species but has been little studied in invasive tree species. In a greenhouse experiment, we compared ecophysiological traits between an invasive species to Europe, <it>Acer negundo</it>, and early- and late-successional co-occurring native species, under different light, nutrient availability and disturbance regimes. We also compared species of the same species groups <it>in </it><it>situ</it>, in riparian forests.</p> <p>Results</p> <p>Under non-limiting resources, <it>A. negundo </it>seedlings showed higher growth rates than the native species. However, <it>A. negundo </it>displayed equivalent or lower photosynthetic capacities and nitrogen content per unit leaf area compared to the native species; these findings were observed both on the seedlings in the greenhouse experiment and on adult trees <it>in situ</it>. These physiological traits were mostly conservative along the different light, nutrient and disturbance environments. Overall, under non-limiting light and nutrient conditions, specific leaf area and total leaf area of <it>A. negundo </it>were substantially larger. The invasive species presented a higher plasticity in allocation to foliage and therefore in growth with increasing nutrient and light availability relative to the native species.</p> <p>Conclusions</p> <p>The higher level of plasticity of the invasive species in foliage allocation in response to light and nutrient availability induced a better growth in non-limiting resource environments. These results give us more elements on the invasiveness of <it>A. negundo </it>and suggest that such behaviour could explain the ability of <it>A. negundo </it>to outperform native tree species, contributes to its spread in European resource-rich riparian forests and impedes its establishment under closed-canopy hardwood forests.</p

The neurobiology of speech perception decline in aging

Speech perception difficulties are common amongst elderlies; yet the underlying neural mechanisms are still poorly understood. New empirical evidence suggesting that brain senescence may be an important contributor to these difficulties have challenged the traditional view that peripheral hearing loss was the main factor in the aetiology of these difficulties. Here we investigated the relationship between structural and functional brain senescence and speech perception skills in aging. Following audiometric evaluations, participants underwent MRI while performing a speech perception task at different intelligibility levels. As expected, with age speech perception declined, even after controlling for hearing sensitivity using an audiological measure (pure tone averages), and a bioacoustical measure (DPOAEs recordings). Our results reveal that the core speech network, centered on the supratemporal cortex and ventral motor areas bilaterally, decreased in spatial extent in older adults. Importantly, our results also show that speech skills in aging are affected by changes in cortical thickness and in brain functioning. Age-independent intelligibility effects were found in several motor and premotor areas, including the left ventral premotor cortex and the right SMA. Agedependent intelligibility effects were also found, mainly in sensorimotor cortical areas, and in the left dorsal anterior insula. In this region, changes in BOLD signal had an effect on the relationship of age to speech perception skills suggesting a role for this region in maintaining speech perception in older ages perhaps by. These results provide important new insights into the neurobiology of speech perception in aging

Cascading the use of Web 2.0 technology in secondary schools in the United Kingdom: identifying the barriers beyond pre-service training

This paper reports on research that took place at Nottingham Trent University and Sheffield Hallam University, United Kingdom, over two years. The research focuses on the use of Web 2.0 technology, specifically web logs, with pre-service teachers, both during their university programme and the first year of teaching as full-time newly qualified teachers (NQTs). The purpose of this research was to add a developing body of knowledge by identifying whether technology used by pre-service teachers during their training course can be cascaded into their practice once qualified. Key findings identify a number of enablers and barriers to cascading technology in the classroom; these include curriculum time, pupil skills and support. The research concludes that early professional support and development should be on-going and assumptions about new teachers as champions of cascading innovative use of Web 2 technologies into their practice as NQTs may be over optimisti