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Abstract: Pappophorum vaginatum is the most abundant C4, warm-season perennial grass in rangelands of northeastern, arid Patagonia, which is often exposed to continuous grazing. Eragrostis curvula is the only naturalized, C4 warm-season genotype that has successfully established from seed during moist years in the study region, that is characterized by a scarce forage availability to livestock during the spring and summer. Successful introduction of perennial forage genotypes is then critical in that region. No studies have yet been conducted to determine the greater abundance of P. vaginatum compared to that of other native C4 grass genotypes (Aristida subulata, A. spegazzinii, Sporobolus cryptandrus) in the study area. The effect of defoliation on arbuscular mycorrhizal colonization was investigated on the four native, one naturalized and five introduced, C3 perennial grass genotypes (Leymus cinereus cvs. “Magnar” and “Trailhead”, and Achnatherum hymenoides cvs. “Paloma”, “Rimrock” and “Nezpar”) growing at the field. We hypothesized that the magnitude of mycorrhizal colonization (1) is similar on defoliated than on undefoliated plants of the native and naturalized genotypes, (2) is greater in the native and naturalized than in the introduced genotypes, and (3) is greatest in P. vaginatum than in all remaining genotypes. Plants of all ten genotypes were either exposed or not to a severe defoliation twice in the growing seasons of 2007/2008 and 2008/2009. The results showed that all studied genotypes maintained arbuscular mycorrhizal colonization levels following defoliation similar to undefoliated controls. The greatest arbuscular mycorrhizal colonization was often found on both cultivars of L. cinereus among all genotypes. The greatest arbuscular mycorrhizal colonization in P. vaginatum than in the other native genotypes at the end of the study, parameter that contributes to defoliation tolerance, could help to explain its greater abundance in rangelands of central Argentina. The higher arbuscular mycorrhizal colonization in both cultivars of L. cinereus might contribute to their successful establishment and survival in rangelands of northeastern, arid Patagonia. Genotype introduction in these rangelands is likely to affect community dynamics because of variable effects of the mycorrhizal symbiosis on the various plant genotypes. [Copyright &y& Elsevier]

Abstract: This study was conducted at two sites, 1.5km from 1 to another in arid Argentina (39°S, 69°W). Vegetation is distributed in patches. Four microenvironments can be identified in the soil surface of these patches, and the bare interspaces among them. Hypotheses were that (1) at any time during the sampling periods, buried (viable+damaged) seeds of the most common vegetation in the patches, Larrea divaricata Cav., Atriplex lampa Gill ex Moquin, Stipa neaei Nees ex Steudel and Leymus erianthus (Phil.) Dubcovsky, are present in the soil seed bank at all four microenvironments within any vegetation patch and its associated interspace, and (2) natural plant recruitment from the soil seed bank occurs for L. divaricata, A. lampa, S. neaei, L. erianthus, Bromus tectorum L. and Poa lanuginosa Poiret ap. Lamarck in all study microenvironments. In undisturbed field areas, 32 soil samples were periodically taken using an auger in 1999. Viable and damaged seeds contained in the soil organic matter were counted for L. divaricata, A. lampa, S. neaei, and L. erianthus. In a further study, emergence and subsequent growth of L. divaricata, A. lampa, S. neaei, L. erianthus, B. tectorum and P. lanuginosa from the soil seed bank were evaluated in the various microenvironments; permanent plots (0.04m2) were placed on each of the two study sites using four vegetation patches and their associated interspaces per site. Results supported the first hypotheses only for L. divaricata and A. lampa. However, natural recruitment from the soil only included S. neaei and P. lanuginosa through asexual, and B. tectorum through sexual reproduction. Despite the presence of buried seeds of L. divaricata and A. lampa in microenvironment 4 during most of the sampling period, bare interspaces among vegetation patches can be naturally vegetated through sexual reproduction by B. tectorum, during years of abundant, higher than long-term, annual precipitation. [Copyright &y& Elsevier]

Social impairment is a cardinal feature of schizophrenia spectrum disorders (SZ). Smaller social network size, diminished social skills, and loneliness are highly prevalent. Existing, gold-standard assessments of social impairment in SZ often rely on self-reported information that depends on retrospective recall and detailed accounts of complex social behaviors. This is particularly problematic in people with SZ given characteristic cognitive impairments and reduced insight. Ecological Momentary Assessment (EMA; repeated self-reports completed in the context of daily life) allows for the measurement of social behavior as it occurs in vivo , yet still relies on participant input. Momentary characterization of behavior using smartphone sensors (e.g., GPS, microphone) may also provide ecologically valid indicators of social functioning. In the current study we tested associations between both active (e.g., EMA-reported number of interactions) and passive (GPS-based mobility, conversations captured by microphone) smartphone-based measures of social activity and measures of social functioning and loneliness to examine the promise of such measures for understanding social impairment in SZ. Our results indicate that passive markers of mobility were more consistently associated with EMA measures of social behavior in controls than in people with SZ. Furthermore, dispositional loneliness showed associations with mobility metrics in both groups, while general social functioning was less related to these metrics. Finally, interactions detected in the ambient audio were more tied to social functioning in SZ than in controls. Findings speak to the promise of smartphone-based digital phenotyping as an approach to understanding objective markers of social activity in people with and without schizophrenia. • Smartphone sensors allow for continuous, unobtrusive assessment. • Mobility from GPS and speech from microphone can be used to quantify social activity. • Each sensor provides unique information for social activity in people with and without schizophrenia. [ABSTRACT FROM AUTHOR]