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5,455 result(s) for "Johnson, Nancy"
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Social psychology of dress
\"Social Psychology of Dress presents and explains the major theories and concepts that are important to understanding relationships between dress and human behavior. These concepts and theories are derived from such disciplines as sociology, psychology, anthropology, communication, and textiles and clothing. Information presented will provide summaries of empirical research, as well as examples from current events or popular culture. The book provides a broad-based and inclusive discussion of the social psychology of dress, including: - The study of dress and how to do it - Cultural topics such as cultural patterns including technology, cultural complexity, normative order, aesthetics, hygiene, ethnicity, ritual - Societal topics such as family, economy-occupation, social organizations and sports, fraternal organizations - Individual-focused theories on deviance, personality variables, self, values, body image and social cognition - Coverage of key theories related to dress and identity provide a strong theoretical foundation for further research Unique chapter features bring in industry application and current events. The end-of-chapter summaries, discussion questions and activities give students opportunities to study and research dress. Teaching resources including an instructor's guide, test bank and PowerPoint presentations with full-color versions of images from the textbook. \"-- Provided by publisher.
Resource stoichiometry elucidates the structure and function of arbuscular mycorrhizas across scales
Despite the fact that arbuscular mycorrhizal (AM) associations are among the most ancient, abundant and important symbioses in terrestrial ecosystems, there are currently few unifying theories that can be used to help understand the factors that control their structure and function. This review explores how a stoichiometric perspective facilitates integration of three complementary ecological and evolutionary models of mycorrhizal structure and function. AM symbiotic function should be governed by the relative availability of carbon, nitrogen and phosphorus (trade balance model) and allocation to plant and fungal structures should depend on the availabilities of these resources (functional equilibrium model). Moreover, in an evolutionary framework, communities of plants and AM fungi are predicted to adapt to each other and their local soil environment (co-adaptation model). Anthropogenic enrichment of essential resources in the environment is known to impact AM symbioses. A more predictive theory of AM structure and function will help us to better understand how these impacts may influence plant communities and ecosystem properties.
Tropical-temperate comparison of landscape-scale arbuscular mycorrhizal fungal species distributions
Aim: Mycorrhizas are among the most common symbioses on Earth, impacting plant community structure and ecosystem functioning, yet little landscape-scale data linking mycorrhizal fungal diversity to biotic and abiotic properties exist to inform conservation. We examined arbuscular mycorrhizal (AM) fungal diversity in tropical and temperate locations and identified potential drivers of species distributions and diversity for use as proxy indicators in biodiversity conservation. Location: AM fungal communities were documented at 60 sites in the Colorado Plateau in south-western United States and La Gran Sabana in south-eastern Venezuela. Methods: Communities of plants and AM fungi and abiotic variables were measured along 50-m transects in three vegetation types (shrublands, forests, and traditional agricultural fields). Model selection and multivariate analyses were used to evaluate environmental predictors of AM fungal diversity and community structure. Results: AM fungal species richness (α diversity) and community structure, but not among-site turnover (β diversity), differed between tropical and temperate locations; only 15% of taxa were present in both locations. In unmanaged sites, AM fungal richness was not correlated with plant richness, but instead predicted by soil pH and temperature (temperate) or precipitation and latitude (tropics). The structure of AM fungal communities was influenced by plant identity but not plant diversity in both locations. Traditional, sedentary Hopi agriculture influenced AM fungal communities on the Colorado Plateau, but Pemón shifting slash-and-burn agriculture did not alter AM fungal communities at La Gran Sabana. At both locations, AM fungal community structure was linked to soil texture and nitrogen. Main conclusions: Our study demonstrates similarity between tropical and temperate regions in the biotic and abiotic drivers of landscape-scale AM fungal species distributions. Soil and climate as well as habitat heterogeneity may serve as proxy indicators of AM fungal communities for use in conservation planning to preserve the ecosystem functions and services of mycorrhizas.
Direct and indirect influences of 8 yr of nitrogen and phosphorus fertilization on Glomeromycota in an alpine meadow ecosystem
We measured the influences of soil fertility and plant community composition on Glomeromycota, and tested the prediction of the functional equilibrium hypothesis that increased availability of soil resources will reduce the abundance of arbuscular mycorrhizal (AM) fungi. Communities of plants and AM fungi were measured in mixed roots and in Elymus nutans roots across an experimental fertilization gradient in an alpine meadow on the Tibetan Plateau. As predicted, fertilization reduced the abundance of Glomeromycota as well as the species richness of plants and AM fungi. The response of the glomeromycotan community was strongly linked to the plant community shift towards dominance by Elymus nutans. A reduction in the extraradical hyphae of AM fungi was associated with both the changes in soil factors and shifts in the plant community composition that were caused by fertilization. Our findings highlight the importance of soil fertility in regulating both plant and glomeromycotan communities, and emphasize that high fertilizer inputs can reduce the biodiversity of plants and AM fungi, and influence the sustainability of ecosystems.
The role of locally adapted mycorrhizas and rhizobacteria in plant—soil feedback systems
Summary The plant–soil feedback (PSF) framework has become an important theory in plant ecology, yet many ecological and evolutionary factors that influence PSFs have yet to be fully considered. Here, we discuss the importance of local adaptation among plants and root‐associated fungi and bacteria. Furthermore, we show how inclusion of the optimal resource allocation (OA) model can help predict the direction and outcome of PSFs under environmental change. Plants and associated soil microbes have co‐evolved for millennia, generating adaptations to each other and to their local environment. This local co‐adaptation is likely generated by a suite of multidirectional exchanges of goods and services among plants, fungi and bacteria, and the constant changes in above‐ground–below‐ground interactions. Resource limitation may be a driver of local adaptation among organisms involved in nutritional symbioses. The OA model states that when an essential resource is limited, natural selection will favour taxa that forage optimally by adjusting their biomass and energy allocation such that productivity is equally limited by all resources. Co‐adaptation will therefore respond to the local limiting resource conditions through taxa‐specific resource transfer interactions. The OA model can help predict the outcomes of PSFs across a range of resource gradients and environmental changes such as increasing drought or atmospheric nitrogen deposition. Positive feedback is predicted in systems where resource exchange among plants and associated soil microbes can ameliorate resource limitation, or in systems where microbes provide another important service such as pathogen defence. Feedback strength is expected to diminish as resources become less limiting. Negative feedback is predicted when resources are in luxury supply and populations of opportunistic plant pathogens increase relative to commensal or mutualist microbes. Future, field‐based studies that integrate naturally co‐occurring systems of plants, microbes and their local soil are needed to further test the hypothesis that resource availability is an effective predictor of the direction and magnitude of PSFs. A more mechanistic understanding of PSFs will help land managers and farmers to manipulate plant–microbial soil interactions to respond to environmental change and to effectively harness beneficial symbioses for plant nutrition and pathogen control. Lay Summary
The roles of livestock in developing countries
Livestock play a significant role in rural livelihoods and the economies of developing countries. They are providers of income and employment for producers and others working in, sometimes complex, value chains. They are a crucial asset and safety net for the poor, especially for women and pastoralist groups, and they provide an important source of nourishment for billions of rural and urban households. These socio-economic roles and others are increasing in importance as the sector grows because of increasing human populations, incomes and urbanisation rates. To provide these benefits, the sector uses a significant amount of land, water, biomass and other resources and emits a considerable quantity of greenhouse gases. There is concern on how to manage the sector's growth, so that these benefits can be attained at a lower environmental cost. Livestock and environment interactions in developing countries can be both positive and negative. On the one hand, manures from ruminant systems can be a valuable source of nutrients for smallholder crops, whereas in more industrial systems, or where there are large concentrations of animals, they can pollute water sources. On the other hand, ruminant systems in developing countries can be considered relatively resource-use inefficient. Because of the high yield gaps in most of these production systems, increasing the efficiency of the livestock sector through sustainable intensification practices presents a real opportunity where research and development can contribute to provide more sustainable solutions. In order to achieve this, it is necessary that production systems become market-orientated, better regulated in cases, and socially acceptable so that the right mix of incentives exists for the systems to intensify. Managing the required intensification and the shifts to new value chains is also essential to avoid a potential increase in zoonotic, food-borne and other diseases. New diversification options and improved safety nets will also be essential when intensification is not the primary avenue for developing the livestock sector. These processes will need to be supported by agile and effective public and private institutions.
Functional team selection as a framework for local adaptation in plants and their belowground microbiomes
Multicellular organisms are hosts to diverse communities of smaller organisms known as microbiomes. Plants have distinctive microbiomes that can provide important functions related to nutrition, defense, and stress tolerance. Empirical studies provide convincing evidence that in some—but not all—circumstances, belowground microbiomes help plants adapt to their local environment. The purpose of this review is to develop functional team selection (FTS) as a framework to help predict the conditions necessary for root microbiomes to generate local adaptation for their plant hosts. FTS envisions plants and their microbiomes as complex adaptive systems, and plant adaptations as emergent properties of these systems. If plants have the capacity to recognize and cultivate beneficial microbes and suppress pathogens, then it is possible for plants to evolve the capacity to gain adaptations by curating their microbiome. In resource-limited and stressful environments, the emergent functions of complex microbial systems may contribute to positive feedback linked to plant vigor, and ultimately, local adaptation. The key factors in this process are: (i) selective force, (ii) host constitution, (iii) microbial diversity, and (iv) time. There is increasing interest in harnessing beneficial microbial interactions in agriculture and many microbial growth-promoting products are commercially available, but their use is controversial because a large proportion of these products fail to consistently enhance plant growth. The FTS framework may help direct the development of durable plant-microbiome systems that enhance crop production and diminish pathogens. It may also provide valuable insights for understanding and managing other kinds of host-microbe systems.
Biocrust moss populations differ in growth rates, stress response, and microbial associates
Aims A growing body of research supports the feasibility of biocrust rehabilitation. Identifying populations of key species that are amenable to cultivation and that are resilient in rehabilitation contexts would advance the efficacy of these technologies. Here we investigate the growth and stress response of the cosmopolitan biocrust moss, Syntrichia ruralis. Methods We sampled populations of S. ruralis along a precipitation seasonality gradient from the Colorado Plateau ecoregion of the western United States. We cultivated these populations in an experiment manipulating duration of hydration periods on a weekly cycle. We then treated greenhouse grown materials with brief, stressful watering events, measuring how many events they could survive. Results All populations grew at an accelerated rate compared to growth in a natural setting, at least doubling biomass in five months. Increasing duration of hydration periods led to more growth in all but one population. Volunteer biocrust algae and cyanobacteria developed during cultivation, and differed among populations. Greenhouse grown mosses differed in their response to stressful watering, with the most susceptible populations dying at half the number events compared to the most tolerant. Conclusions These findings argue for informed selection and deployment of Syntrichia ruralis populations for soil rehabilitation.
Untangling the biological contributions to soil stability in semiarid shrublands
Communities of plants, biological soil crusts (BSCs), and arbuscular mycorrhizal (AM) fungi are known to influence soil stability individually, but their relative contributions, interactions, and combined effects are not well understood, particularly in arid and semiarid ecosystems. In a landscape-scale field study we quantified plant, BSC, and AM fungal communities at 216 locations along a gradient of soil stability levels in southern Utah, USA. We used multivariate modeling to examine the relative influences of plants, BSCs, and AM fungi on surface and subsurface stability in a semiarid shrubland landscape. Models were found to be congruent with the data and explained 35% of the variation in surface stability and 54% of the variation in subsurface stability. The results support several tentative conclusions. While BSCs, plants, and AM fungi all contribute to surface stability, only plants and AM fungi contribute to subsurface stability. In both surface and subsurface models, the strongest contributions to soil stability are made by biological components of the system. Biological soil crust cover was found to have the strongest direct effect on surface soil stability (0.60; controlling for other factors). Surprisingly, AM fungi appeared to influence surface soil stability (0.37), even though they are not generally considered to exist in the top few millimeters of the soil. In the subsurface model, plant cover appeared to have the strongest direct influence on soil stability (0.42); in both models, results indicate that plant cover influences soil stability both directly (controlling for other factors) and indirectly through influences on other organisms. Soil organic matter was not found to have a direct contribution to surface or subsurface stability in this system. The relative influence of AM fungi on soil stability in these semiarid shrublands was similar to that reported for a mesic tallgrass prairie. Estimates of effects that BSCs, plants, and AM fungi have on soil stability in these models are used to suggest the relative amounts of resources that erosion control practitioners should devote to promoting these communities. This study highlights the need for system approaches in combating erosion, soil degradation, and arid-land desertification.