127 research outputs found
Condominium Housing: Some Social and Economic Implications
The functioning of condominium communities and projects has received increased attention from housing analysts in many professions. As of 1973, there were an estimated 15,000 condominium and townhouse communities in the United States, a figure expanding approximately by 4,000 annually.
In this context, the proliferation of home owners associations in the communities or projects is of special interest due to their emerging role as a new form of residential government. This role manifests itself as both supplementary and in part complementary to the existing government framework. The collective provision and maintenance of selected services, including roads, utilities, lighting, refuse collection, recreational facilities and others, closely resemble and augment many services offered by cities and counties. The police power manifested as zoning and building controls in cities and counties translates itself into architectural and design control, and various property use, occupancy and related restrictions, in community associations. Much has been written on the methods of organizing these associations, but often discussion is couched in very practical terms without reference to underlying social and economic concepts which may influence effectiveness in meeting perceived problems. Generally, the goal here is to try and bridge this gap
Diversity of Meiofauna from the 9°50′N East Pacific Rise across a Gradient of Hydrothermal Fluid Emissions
Background: We studied the meiofauna community at deep-sea hydrothermal vents along a gradient of vent fluid emissions in the axial summit trought (AST) of the East Pacific Rise 9 degrees 50'N region. The gradient ranged from extreme high temperatures, high sulfide concentrations, and low pH at sulfide chimneys to ambient deep-sea water conditions on bare basalt. We explore meiofauna diversity and abundance, and discuss its possible underlying ecological and evolutionary processes.
Methodology/Principal Findings: After sampling in five physico-chemically different habitats, the meiofauna was sorted, counted and classified. Abundances were low at all sites. A total of 52 species were identified at vent habitats. The vent community was dominated by hard substrate generalists that also lived on bare basalt at ambient deep-sea temperature in the axial summit trough (AST generalists). Some vent species were restricted to a specific vent habitat (vent specialists), but others occurred over a wide range of physico-chemical conditions (vent generalists). Additionally, 35 species were only found on cold bare basalt (basalt specialists). At vent sites, species richness and diversity clearly increased with decreasing influence of vent fluid emissions from extreme flow sulfide chimney (no fauna), high flow pompei worm (S: 4-7, H-loge': 0.11-0.45), vigorous flow tubeworm (S: 8-23; H-loge': 0.44-2.00) to low flow mussel habitats (S: 28-31; H-loge': 2.34-2.60).
Conclusions/Significance: Our data suggest that with increasing temperature and toxic hydrogen sulfide concentrations and increasing amplitude of variation of these factors, fewer species are able to cope with these extreme conditions. This results in less diverse communities in more extreme habitats. The finding of many species being present at sites with and without vent fluid emissions points to a non endemic deep-sea hydrothermal vent meiofaunal community. This is in contrast to a mostly endemic macrofauna but similar to what is known for meiofauna from shallow-water vents
The Numbers Behind Mushroom Biodiversity
Fungi are among the most diverse groups of organisms on Earth. with a global diversity estimated at 0.8 million to 5.1 million species. They play fundamental ecological roles as decomposers, mutualists, and pathogens, growing in almost all habitats and being important as sources of food and health benefits, income, and to maintain forest health. Global assessment of wild edible fungi indicate the existence of 2327 useful wild species; 2166 edible and 1069 used as food; 470 medicinal species. Several million tonnes are collected, consumed, and sold each year in over 80 countries. The major mushroom-producing countries in 2012 were China, Italy, USA, and The Netherlands, with 80% of the world production, 64% of which came from China. The European Union produces 24% of the world production. Italy is the largest European producer, Poland is the largest exporter, UK the largest importer.Fungi are difficult to preserve and fossilize and due to the poor preservation of most
fungal structures, it has been difficult to interpret the fossil record of fungi. Hyphae,
the vegetative bodies of fungi, bear few distinctive morphological characteristicss,
and organisms as diverse as cyanobacteria, eukaryotic algal groups, and oomycetes
can easily
be mistaken for them (Taylor & Taylor 1993). Fossils provide minimum
ages for divergences and genetic lineages can be much older than even the oldest
fossil representative found. According to Berbee and Taylor (2010), molecular clocks
(conversion of molecular changes into geological time) calibrated by fossils are the
only available tools to estimate timing of evolutionary events in fossil‐poor groups,
such as fungi.
The arbuscular mycorrhizal symbiotic fungi from the division Glomeromycota, generally
accepted as the phylogenetic sister clade to the Ascomycota and Basidiomycota,
have left the most ancient fossils in the Rhynie Chert of Aberdeenshire in the north of
Scotland (400 million years old). The Glomeromycota and several other fungi have been
found associated with the preserved tissues of early vascular plants (Taylor et al. 2004a).
Fossil spores from these shallow marine sediments from the Ordovician that closely
resemble Glomeromycota spores and finely branched hyphae arbuscules within plant
cells were clearly preserved in cells of stems of a 400 Ma primitive land plant,
Aglaophyton, from Rhynie chert 455–460 Ma in age (Redecker et al. 2000; Remy et al.
1994) and from roots from the Triassic (250–199 Ma) (Berbee & Taylor 2010; Stubblefield
et al. 1987).info:eu-repo/semantics/publishedVersio
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