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33,682 result(s) for "community composition"
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The artist's library : a field guide
\"Creativity, like information, is free to everyone who steps into a library. [This book] offers the idea that an artist is any person who uses creative tools to make new things, and the guidance and resources to make libraries of all sizes and shapes come alive as spaces for art-making and cultural engagement. Case studies included in the book range from the crafty (pop-up books) to the community-minded (library galleries) to documentary (photo projects) to the technically complex ('listening' to libraries via Dewey decimal frequencies)\"-- Provided by publisher.
Critical transition of soil bacterial diversity and composition triggered by nitrogen enrichment
Soil bacterial communities are pivotal in regulating terrestrial biogeochemical cycles and ecosystem functions. The increase in global nitrogen (N) deposition has impacted various aspects of terrestrial ecosystems, but we still have a rudimentary understanding of whether there is a threshold for N input level beyond which soil bacterial communities will experience critical transitions. Using high-throughput sequencing of the 16S rRNA gene, we examined soil bacterial responses to a long-term (13 yr), multi-level, N addition experiment in a temperate steppe of northern China. We found that plant diversity decreased in a linear fashion with increasing N addition. However, bacterial diversity responded nonlinearly to N addition, such that it was unaffected by N input below 16 g N·m−2·yr−1, but decreased substantially when N input exceeded 32 g N·m−2·yr−1. A meta-analysis across four N addition experiments in the same study region further confirmed this nonlinear response of bacterial diversity to N inputs. Substantial changes in soil bacterial community structure also occurred between N input levels of 16 to 32 g N·m−2·yr−1. Further analysis revealed that the loss of soil bacterial diversity was primarily attributed to the reduction in soil pH, whereas changes in soil bacterial community were driven by the combination of increased N availability, reduced soil pH, and changes in plant community structure. In addition, we found that N addition shifted bacterial communities toward more putatively copiotrophic taxa. Overall, our study identified a threshold of N input level for bacterial diversity and community composition. The nonlinear response of bacterial diversity to N input observed in our study indicates that although bacterial communities are resistant to low levels of N input, further increase in N input could trigger a critical transition, shifting bacterial communities to a low-diversity state.
Relocating Authority : Japanese Americans Writing to Redress Mass Incarceration
\"Relocating Authority examines the ways Japanese Americans have continually used writing to respond to the circumstances of their community's mass imprisonment during World War II. Using both Nikkei cultural frameworks and community-specific history for methodological inspiration and guidance, Mira Shimabukuro shows how writing was used privately and publicly to individually survive and collectively resist the conditions of incarceration. Examining a wide range of diverse texts and literacy practices such as diary entries, note-taking, manifestos, and multiple drafts of single documents, Relocating Authority draws upon community archives, visual histories, and Asian American history and theory to reveal the ways writing has served as a critical tool for incarcerees and their descendants. Incarcerees not only used writing to redress the 'internment' in the moment but also created pieces of text that enabled and inspired further redress long after the camps had closed. Relocating Authority highlights literacy's enduring potential to participate in social change and assist an imprisoned people in relocating authority away from their captors and back to their community and themselves. It will be of great interest to students and scholars of ethnic and Asian American rhetorics, American studies, and anyone interested in the relationship between literacy and social justice\"-- Provided by publisher.
The missing link in grassland restoration: arbuscular mycorrhizal fungi inoculation increases plant diversity and accelerates succession
Summary Because soil microbial communities are often altered by anthropogenic disturbance, successful plant community restoration may require the restoration of beneficial soil microbes, such as arbuscular mycorrhizal (AM) fungi. Recent evidence suggests that later successional grassland species are more strongly affected by AM fungi relative to early successional plants and that late successional plants consistently benefit from some AM fungi but not other AM fungal species. Many of these late successional species are also often missing in restorations despite being heavily seeded. To assess the effects of AM fungal composition within grassland restorations, we inoculated plots with six different AM fungal community treatments including one of four different AM fungal species isolated from a prairie, a mixture of all four fungal species, and a non‐inoculated control. AM fungi were introduced by planting 16 different inoculated nurse plants into replicated plots. We also seeded the restoration with a diverse, 54 species prairie seed mixture. We found that AM fungal inoculation drove plant community composition; plots inoculated with certain AM fungal treatments were dominated by desirable prairie plants, whereas plots inoculated with other AM fungal species and the non‐inoculated control were dominated by non‐desirable plants including weeds and exotic species. Specifically, we found that many early successional species established well regardless of AM fungal inoculation, whereas the establishment and growth of many late successional species was strongly dependent on the presence of specific AM fungal species. Many conservative late successional species did not occur without inoculation. Overall, total plant community richness, diversity, and Floristic Quality Index were all significantly improved with AM fungal inoculation, whereas we observed that non‐desirable plant abundance was significantly greater in the non‐inoculated plots. Synthesis and applications. Our results suggest that the lack of late successional establishment reported in many previous restorations may be due to ineffective arbuscular mycorrhizal fungal communities at these sites. We conclude that the reintroduction of arbuscular mycorrhizal fungi from reference prairie environments could improve restoration outcomes by promoting plant diversity and richness, especially for desirable later successional plant species, while simultaneously inhibiting less desirable weedy plants. Our results suggest that the lack of late successional establishment reported in many previous restorations may be due to ineffective arbuscular mycorrhizal fungal communities at these sites. We conclude that the reintroduction of arbuscular mycorrhizal fungi from reference prairie environments could improve restoration outcomes by promoting plant diversity and richness, especially for desirable later successional plant species, while simultaneously inhibiting less desirable weedy plants.
Nitrogen addition reduces soil respiration but increases the relative contribution of heterotrophic component in an alpine meadow
Disentangling the relative response sensitivity of soil autotrophic (Ra) and heterotrophic respiration (Rh) to nitrogen (N) enrichment is pivotal for evaluating soil carbon (C) storage and stability in the scenario of intensified N deposition. However, the mechanisms underlying differential sensitivities of Ra and Rh and relative contribution of Rh to soil respiration (Rs) with increasing N deposition remain elusive. A manipulative field experiment with multi‐level N addition rates was conducted over 3 years (2015–2017) in an alpine meadow to explore the relative impact of N enrichment on Ra and Rh and the response of Rh/Rs ratio to the gradient of N addition. Soil respiration components had different sensitivities to N enrichment, with Ra decreasing more than Rh, leading to a higher Rh/Rs ratio as a function of increasing N addition rates. Ra and Rh decreased nonlinearly as N addition rates increased, with a critical load of 8 g N m−2 year−1 above which N enrichment significantly inhibited them. Ra and Rh were controlled by different abiotic and biotic factors, and the regulation of controlling factors on soil respiration components varied over time. N‐induced reduction in the relative abundance of forb significantly affected Ra, and this effect was mainly evident in the second and third years. Nitrogen enrichment significantly changed Rh in the third year, and the decreased Rh under high doses of N addition could be attributed to the changes in microbial biomass C, soil substrate quality and microbial composition. Our study highlights the leading role of Ra in regulating Rs responses to N enrichment and the enhancement of Rh/Rs ratio with increasing N addition. We also emphasize that N‐induced shifts in plant community composition play a vital role in regulating Ra instead of Rh. The changing drivers of Ra and Rh with time suggests that long‐term experiments with multiple levels of N addition are further needed to test the nonlinear responses and underlying mechanisms of soil respiration components in face to aggravating N deposition. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.
Identifying environmental factors affecting the microbial community composition on outdoor structural timber
Timber wood is a building material with many positive properties. However, its susceptibility to microbial degradation is a major challenge for outdoor usage. Although many wood-degrading fungal species are known, knowledge on their prevalence and diversity causing damage to exterior structural timber is still limited. Here, we sampled 46 decaying pieces of wood from outdoor constructions in the area of Hamburg, Germany; extracted their DNA; and investigated their microbial community composition by PCR amplicon sequencing of the fungal ITS2 region and partial bacterial 16S rRNA genes. In order to establish a link between the microbial community structure and environmental factors, we analysed the influence of wood species, its C and N contents, the effect of wood-soil contact, and the importance of its immediate environment (city, forest, meadow, park, respectively). We found that fungal and bacterial community composition colonising exterior timber was similar to fungi commonly found in forest deadwood. Of all basidiomycetous sequences retrieved, some, indicative for Perenniporia meridionalis , Dacrymyces capitatus , and Dacrymyces stillatus , were more frequently associated with severe wood damage. Whilst the most important environmental factor shaping fungal and bacterial community composition was the wood species, the immediate environment was important for fungal species whilst, for the occurrence of bacterial taxa, soil contact had a high impact. No influence was tangible for variation of the C or N content. In conclusion, our study demonstrates that wood colonising fungal and bacterial communities are equally responsive in their composition to wood species, but respond differently to environmental factors. Key points •  Perenniporia meridionalis and Dacrymyces are frequently associated with wood damage •  Fungal community composition on timber is affected by its surrounding environment •  Bacterial community composition on structural timber is affected by soil contact
Changes in plant community composition, not diversity, during a decade of nitrogen and phosphorus additions drive above‐ground productivity in a tallgrass prairie
Nutrient additions typically increase terrestrial ecosystem productivity, reduce plant diversity and alter plant community composition; however, the effects of P additions and interactions between N and P are understudied. We added both N (10 g m⁻²) and three levels of P (2.5, 5 and 10 g m⁻²) to a native, ungrazed tallgrass prairie burned biennially in northeastern Kansas, USA, to determine the independent and interactive effects of N and P on plant community composition and above‐ground net primary productivity (ANPP). After a decade of nutrient additions, we found few effects of P alone on plant community composition, N alone had stronger effects, and N and P additions combined resulted in much larger effects than either alone. The changes in the plant community were driven by decreased abundance of C₄ grasses, perhaps in response to altered interactions with mycorrhizal fungi, concurrent with increased abundance of non‐N‐fixing perennial and annual forbs. Surprisingly, this large shift in plant community composition had little effect on plant community richness, evenness and diversity. The shift in plant composition with N and P combined had large but variable effects on ANPP over time. Initially, N and N and P combined increased above‐ground productivity of C₄ grasses, but after 4 years, productivity returned to ambient levels as grasses declined in abundance and the community shifted to dominance by non‐N‐fixing and annual forbs. Once these forbs increased in abundance and became dominant, ANPP was more variable, with pulses in forb production only in years when the site was burned. Synthesis. We found that a decade of N and P additions interacted to drive changes in plant community composition, which had large effects on ecosystem productivity but minimal effects on plant community diversity. The large shift in species composition increased variability in ANPP over time as a consequence of the effects of burning. Thus, increased inputs of N and P to terrestrial ecosystems have the potential to alter stability of ecosystem function over time, particularly within the context of natural disturbance regimes.
Floral identity and availability along with surrounding landscapes affect pollinator communities in eastern Tennessee
ContextAnthropogenic land use can significantly alter insect communities and may threaten services provided by beneficial flower-visiting insects. However, the plant community composition may interact with surrounding land use to affect insects in a way that is not well understood.ObjectivesOur goal was to disentangle the effect of the background plant community on the flowering visiting insect community composition from the independent effect of surrounding land use.MethodsWe planted four fixed community garden plots, three that each contained six species of one plant family (Asteraceae, Fabaceae, Lamiaceae) and one that was a mixed community plot, controlling the number of individuals and species identity of the plants. We then replicated these four fixed plots across five different landscapes in eastern Tennessee and surveyed the insects that visited the flowers for 2 years.ResultsBoth the identity and abundance of floral resources were strong drivers of flower-visiting insect abundance, with floral display being the single largest driver. Independent of the plant community, specific pollinating insects responded to different types of land use at different radii around each site. Total flower visitor and soldier beetle abundance increased with agricultural land use at 500 and 2000 m, respectively. On the other hand, sweat bee abundance increased with semi-natural land use at 2000 m and honey bee abundance increased with developed land use at 1000 m.ConclusionIndependent of plant community composition, surrounding land use affected the abundance, diversity, and composition of flower-visiting insects. However, there was not one consistent land use effect across all flower-visiting insects.
Experimental drought reduces the transfer of recently fixed plant carbon to soil microbes and alters the bacterial community composition in a mountain meadow
Drought affects plants and soil microorganisms, but it is still not clear how it alters the carbon (C) transfer at the plant–microbial interface. Here, we tested direct and indirect effects of drought on soil microbes and microbial turnover of recent plant-derived C in a mountain meadow. Microbial community composition was assessed using phospholipid fatty acids (PLFAs); the allocation of recent plant-derived C to microbial groups was analysed by pulse-labelling of canopy sections with 13CO2 and the subsequent tracing of the label into microbial PLFAs. Microbial biomass was significantly higher in plots exposed to a severe experimental drought. In addition, drought induced a shift of the microbial community composition, mainly driven by an increase of Gram-positive bacteria. Drought reduced belowground C allocation, but not the transfer of recently plant-assimilated C to fungi, and in particular reduced tracer uptake by bacteria. This was accompanied by an increase of 13C in the extractable organic C pool during drought, which was even more pronounced after plots were mown. We conclude that drought weakened the link between plant and bacterial, but not fungal, C turnover, and facilitated the growth of potentially slow-growing, drought-adapted soil microbes, such as Gram-positive bacteria.
Antibiotics, Antibiotic Resistance Genes, and Bacterial Community Composition in Fresh Water Aquaculture Environment in China
Environmental antibiotic resistance has drawn increasing attention due to its great threat to human health. In this study, we investigated concentrations of antibiotics (tetracyclines, sulfonamides and (fluoro)quinolones) and abundances of antibiotic resistance genes (ARGs), including tetracycline resistance genes, sulfonamide resistance genes, and plasmid-mediated quinolone resistance genes, and analyzed bacterial community composition in aquaculture environment in Guangdong, China. The concentrations of sulfametoxydiazine, sulfamethazine, sulfamethoxazole, oxytetracycline, chlorotetracycline, doxycycline, ciprofloxacin, norfloxacin, and enrofloxacin were as high as 446 μg kg⁻¹ and 98.6 ng L⁻¹ in sediment and water samples, respectively. The relative abundances (ARG copies/16S ribosomal RNA (rRNA) gene copies) of ARGs (sul1, sul2, sul3, tetM, tetO, tetW, tetS, tetQ, tetX, tetB/P, qepA, oqxA, oqxB, aac(6′)-Ib, and qnrS) were as high as 2.8 × 10⁻². The dominant phyla were Proteobacteria, Bacteroidetes, and Firmicutes in sediment samples and Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The genera associated with pathogens were also observed, such as Acinetobacter, Arcobacter, and Clostridium. This study comprehensively investigated antibiotics, ARGs, and bacterial community composition in aquaculture environment in China. The results indicated that fish ponds are reservoirs of ARGs and the presence of potential resistant and pathogen-associated taxonomic groups in fish ponds might imply the potential risk to human health.