125 research outputs found

    RURAL GROWTH IN U.S. HEARTLAND

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    This study identifies factors that explain growth in rural areas using data from 618 counties in the U.S. rural heartland. We evaluate many of the growth hypotheses in the context of sectoral employment growth for counties in Iowa, Minnesota, Missouri, Kansas, Nebraska, South Dakota and North Dakota. Separate estimates for rural and urban counties provide insight into factors that are important in explaining employment growth. The results support the importance of human capital as a factor contributing to sectoral employment growth and show that increased concentration and specialization of employment within a county lead to slower growth in the rural heartland counties.Community/Rural/Urban Development,

    Specific arrangements of species dominance can be more influential than evenness in maintaining ecosystem process and function

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    The ecological consequences of species loss are widely studied, but represent an end point of environmental forcing that is not always realised. Changes in species evenness and the rank order of dominant species are more widespread responses to directional forcing. However, despite the repercussions for ecosystem functioning such changes have received little attention. Here, we experimentally assess how the rearrangement of species dominance structure within specific levels of evenness, rather than changes in species richness and composition, affect invertebrate particle reworking and burrow ventilation behaviour - important moderators of microbial-mediated remineralisation processes in benthic environments - and associated levels of sediment nutrient release. We find that the most dominant species exert a disproportionate influence on functioning at low levels of evenness, but that changes in biomass distribution and a change in emphasis in species-environmental interactions become more important in governing system functionality as evenness increases. Our study highlights the need to consider the functional significance of alterations to community attributes, rather than to solely focus on the attainment of particular levels of diversity when safeguarding biodiversity and ecosystems that provide essential services to society

    Morphological and Agronomic Variability among Cultivars, Landraces, and Genebank Accessions of Purple Passion Fruit, Passiflora edulis f. edulis

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    Global demand for juice of the purple passion fruit, Passiflora edulis f. edulis, is growing, making it a promising species for farmers to grow in the highland tropics, to which it is adapted. However, research centers and private companies have done little to produce new high-yielding varieties. The objective of the present study, therefore, was to evaluate the agronomic and morphological characteristics of 50 passion fruit genotypes across two different elevations and agro-ecological sites as a base for germplasm enhancement. Three groups of genotypes were commercial cultivars (8 genotypes), genebank accessions (8), and landraces (34) collected from throughout the highlands of Colombia. The locations were at 1800 m above sea level (masl) (Pasca), in a place where cultivation of passion fruits is common; and at 2500 masl (SusacĂłn), at a higher elevation site compared with most commercial plantings equal to a new agroecology for cultivation of the crop. Results indicated that the mid-elevation site produced higher yields (kg fruit/plant) than the high elevation site, although some landraces were highly productive there. Commercial cultivar and genebank accessions clustered together in a principal component analysis (PCA); while landraces showed high levels of variation in the trait descriptors with five different clusters. Therefore, landraces of purple passion fruit contained greater genetic diversity than commercial cultivars or the genebank, and breeding programs for the crop should use landraces to increase diversity of varieties available to producers and to further expand the crop to new regions, at higher elevations, or with different agro-ecologies

    Abundance changes of neophytes and native species indicate a thermophilisation and eutrophisation of the Swiss flora during the 20th century

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    During the 20th century human activities drastically altered the natural environment at global and local scales by habitat destruction, urbanisation, intensive agriculture, and climate warming. This anthropogenic pressure has modified species distributions and abundances, and led to the increased spread of neophytes. However, the determination of the magnitude, direction, and drivers of changes remains challenging as comparable historic data is often lacking. Here, we analysed the floristic shifts during the 20th century based on a historic (1900–1930) and current (2000–2017) floristic survey of the canton of Zurich (Switzerland; 1729 km2) in combination with Landolt ecological indicator values (EIVs) for vascular plants. We used two complementary approaches to quantify the floristic shifts using EIVs for temperature, moisture, continentality, nutrients, soil pH and available light. 1) Regarding 244 map tiles with each a 3 × 3 km2 area, we compared the average EIVs for neophytes (i.e., novel species arriving of expanding in the study area) and native species (i.e., species present in Switzerland for centuries). 2) Based on standardized species abundances in the historic and the current flora, we analysed the directed changes by comparing the species’ EIVs of different frequency classes for both the historic and current floristic surveys. Our results showed, that neophyte species arriving or spreading in the study area indicate both a thermophilisation and an eutrophisation. The observed shift in average EIVs for temperature corresponded to about 2 ◩C, which is in line with the calculated difference in niche centroids for neophytes and native species based on their global distribution (1.78 ◩C). The indicated thermophilisation and eutrophisation relate to the decrease in abundances of cold-adapted species and species of nutrient poor environments as well as the increase of warm-adapted and nitrophilous/ruderal species. Directed changes in the flora of the study area are likely to be driven by both climatic changes and land-use changes. Increases in trade activity, anthropogenic habitat disturbances and rising temperatures facilitate the establishment and spread of neophytes from warmer and drier regions. In parallel, wetland area and wetland species strongly decreased as well as species thriving on nutrient-poor sites due to intensified agriculture and nitrogen deposition

    Mind the gaps : comparison of representative vs opportunistic assessment of tree regeneration in Central European beech forests

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    Tree regeneration (TR) in canopy gaps is a key process to understand how forest ecosystems might adapt to future environmental changes. Since successful TR is the result of a complex interplay of several stochastic events such as gap formation, seed production, ungulate pressure and diseases, some of the processes have been neglected or strongly reduced for model applications. Most empirical data on TR originate from (national) forest inventories based on statistically optimized designs for timber resource estimations and use geographically fixed permanent plots. Consequently, these representative samples record TR both in gaps as well as under closed canopy conditions. In this study, we compared TR in 63 representative plots of the Swiss National Forest Inventory (‘NFI sampling’), located in beech and silver fir-beech forests along an elevation gradient in the Jura Mts., with an opportunistic ‘gap sampling’ strategy targeting TR-clusters. We analyzed quantitative (e.g., number of individuals) and qualitative (e.g., species diversity, similarity to surrounding canopy) differences between the ‘NFI sampling’ and ‘gap sampling,’ as well as the environmental factors (e.g., gap size, cluster age, elevation) influencing the composition of TR in small canopy gaps. The ‘gap sampling’ recorded higher median TR densities (+62%, stems ha 1) and species richness (4.0 ± 2.1, mean ± sd) than the ‘NFI sampling’. More importantly, the ‘gap sampling’ provided much more consistent results among sites (i.e., 4x lower variance). Consequently, the ‘gap sampling’ revealed not only general but also species-specific patterns across TR size classes and along elevational gradients in contrast to the lack of patterns in the ‘NFI sampling’. Species richness decreased as TR grew taller, and the tallest TR size class (>130 cm) was almost solely comprised of the dominant species in the surrounding canopy (direct ingrowth). The high amount of direct ingrowth in TR indicates that small canopy gaps might offer only limited management potential to alter forests and that extensive disturbances or management at early TR stages (sapling) would be necessary to promote species better suited to the expected future site conditions. We raise the question of whether a forest monitoring that is statistically optimized for timber resource estimation is best suited to detect adaptation effects to quickly changing environments best visible at the regeneration stage, or whether forest inventory tools should be extended by methods that focus on disturbed parts of forests where changes and adaptations take place. We propose the implementation of an opportunistic gap-based monitoring of TR that essentially serves to identify the best forest management strategies (e.g. gap size, intervention intervals) in forests adapting to environmental change

    SNP Genotyping for Purity Assessment of a Forage Oat (Avena sativa L.) Variety from Colombia

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    Single nucleotide polymorphism (SNP) markers have multiple applications in plant breeding of small grains. They are used for the selection of divergent parents, the identification of genetic variants and marker-assisted selection. However, the use of SNPs in varietal purity assessment is under-reported, especially for multi-line varieties from the public sector. In the case of variety evaluation, these genetic markers are tools for maintaining varietal distinctness, uniformity and stability needed for cultivar release of multi-line or pure-line varieties of inbred crops. The objective of this research was to evaluate the purity and relationships of one original (AV-25) and two multi-line sub-populations (AV25-T and AV25-S) of the inbreeding species, oats (Avena sativa L.). Both sub-populations could be useful as forages in the central highland region of Colombia (\u3e2000 masl), such as in the departments of Boyacå and Cundinamarca, even though they were derived from an original composite mixture widely used in the mountainsides of the southern department of Nariño named Avena 25. Representative single plant selections (SPS) from the two sub-populations were grown together with SPS harvests from off-type plants (early and late) and plants from the original AV25 composite mixture, to determine their genetic similarity. Plants were genotyped by DNA extraction of a plateful of 96 individual plant samples and SNPs were detected for an Illumina Infinium 6K Chip assay. The data were used for the analysis of genetic structure and population relationships. The grouping observed based on the genetic data indicated that AV25-T and AV25-S were homogeneous populations and somewhat divergent in their genetic profile compared to the original AV25-C mix. In addition, to the two commercial, certified oat varieties (Cajicå and Cayuse) were different from these. The early and late selections were probable contaminants and could be discarded. We concluded that the use of SNP markers is an appropriate tool for ensuring genetic purity of oat varieties

    Salvage logging effects on regulating and supporting ecosystem services. A systematic map

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    Wildfires, insect outbreaks, and windstorms are increasingly common forest disturbances.Post-disturbance management often involves salvage logging, i.e. the felling and removal of the affected trees. However, this practice may represent an additional disturbance witheffects on ecosystem processes and services. We developed a systematic map to provide an overview of the primary studies on this topic, and created a database with information on the characteristics of the retrieved publications, including information on stands, disturbance, intervention, measured outcomes, and study design. Of 4341 retrieved publications, 90 were retained in the systematic map. These publications represented 49 studies, predominantly from North America and Europe. Salvage logging after wildfire was addressed more frequently than after insect outbreaks or windstorms. Most studies addressed logging after a single disturbance event, and replication of salvaged stands rarely exceeded 10. The most frequent response variables were tree regeneration, ground cover, and deadwood characteristics.Junta de AndalucĂ­aREMEDINA

    The HUTUBS head-related transfer function (HRTF) database

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    The database contains head-related transfer functions, 3D head meshes, anthropometric features, and headphone transfer functions of 96 subjects

    Metabolite-related dietary patterns and the development of islet autoimmunity

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    The role of diet in type 1 diabetes development is poorly understood. Metabolites, which reflect dietary response, may help elucidate this role. We explored metabolomics and lipidomics differences between 352 cases of islet autoimmunity (IA) and controls in the TEDDY (The Environmental Determinants of Diabetes in theYoung) study. We created dietary patterns reflecting pre-IA metabolite differences between groups and examined their association with IA. Secondary outcomes included IA cases positive for multiple autoantibodies (mAb+). The association of 853 plasma metabolites with outcomes was tested at seroconversion to IA, just prior to seroconversion, and during infancy. Key compounds in enriched metabolite sets were used to create dietary patterns reflecting metabolite composition, which were then tested for association with outcomes in the nested case-control subset and the full TEDDY cohort. Unsaturated phosphatidylcholines, sphingomyelins, phosphatidylethanolamines, glucosylceramides, and phospholipid ethers in infancy were inversely associated with mAb+ risk, while dicarboxylic acids were associated with an increased risk. An infancy dietary pattern representing higher levels of unsaturated phosphatidylcholines and phospholipid ethers, and lower sphingomyelins was protective for mAb+ in the nested case-control study only. Characterization of this high-risk infant metabolomics profile may help shape the future of early diagnosis or prevention efforts
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