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Diversity, Volume 4, Issue 4 (December 2012), Pages 363-491

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Research

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Open AccessArticle Soil Nematodes and Their Prokaryotic Prey Along an Elevation Gradient in The Mojave Desert (Death Valley National Park, California, USA)
Diversity 2012, 4(4), 363-374; doi:10.3390/d4040363
Received: 27 August 2012 / Revised: 16 September 2012 / Accepted: 27 September 2012 / Published: 15 October 2012
Cited by 3 | PDF Full-text (526 KB) | HTML Full-text | XML Full-text
Abstract
We characterized soil communities in the Mojave Desert across an elevation gradient. Our goal was to test the hypothesis that as soil quality improved with increasing elevation (due to increased productivity), the diversity of soil prokaryotes and nematodes would also increase. Soil [...] Read more.
We characterized soil communities in the Mojave Desert across an elevation gradient. Our goal was to test the hypothesis that as soil quality improved with increasing elevation (due to increased productivity), the diversity of soil prokaryotes and nematodes would also increase. Soil organic matter and soil moisture content increased with elevation as predicted. Soil salinity did not correlate to elevation, but was highest at a mid-gradient, alluvial site. Soil nematode density, community trophic structure, and diversity did not show patterns related to elevation. Similar results were obtained for diversity of bacteria and archaea. Relationships between soil properties, nematode communities, and prokaryotic diversity were site-specific. For example, at the lowest elevation site, nematode communities contained a high proportion of fungal-feeding species and diversity of bacteria was lowest. At a high-salinity site, nematode density was highest, and overall, nematode density showed an unexpected, positive correlation to salinity. At the highest elevation site, nematode density and species richness were attenuated, despite relatively high moisture and organic matter content for the soils. Our results support emerging evidence for the lack of a relationship between productivity and the diversity of soil nematodes and prokaryotes. Full article
(This article belongs to the Special Issue Soil Quality and Ecosystem)
Open AccessArticle The Effect of Tillage System and Crop Rotation on Soil Microbial Diversity and Composition in a Subtropical Acrisol
Diversity 2012, 4(4), 375-395; doi:10.3390/d4040375
Received: 29 August 2012 / Revised: 11 October 2012 / Accepted: 19 October 2012 / Published: 31 October 2012
Cited by 12 | PDF Full-text (729 KB) | HTML Full-text | XML Full-text
Abstract
Agricultural management alters physical and chemical soil properties, which directly affects microbial life strategies and community composition. The microbial community drives important nutrient cycling processes that can influence soil quality, cropping productivity and environmental sustainability. In this research, a long-term agricultural experiment [...] Read more.
Agricultural management alters physical and chemical soil properties, which directly affects microbial life strategies and community composition. The microbial community drives important nutrient cycling processes that can influence soil quality, cropping productivity and environmental sustainability. In this research, a long-term agricultural experiment in a subtropical Acrisol was studied in south Brazil. The plots at this site represent two tillage systems, two nitrogen fertilization regimes and three crop rotation systems. Using Illumina high-throughput sequencing of the 16S rRNA gene, the archaeal and bacterial composition was determined from phylum to species level in the different plot treatments. The relative abundance of these taxes was correlated with measured soil properties. The P, Mg, total organic carbon, total N and mineral N were significantly higher in the no-tillage system. The microbial diversity was higher in the no-tillage system at order, family, genus and species level. In addition, overall microbial composition changed significantly between conventional tillage and no-tillage systems. Anaerobic bacteria, such as clostridia, dominate in no-tilled soil as well as anaerobic methanogenic archaea, which were detected only in the no-tillage system. Microbial diversity was higher in plots in which only cereals (oat and maize) were grown. Soil management influenced soil biodiversity on Acrisol by change of composition and abundance of individual species. Full article
(This article belongs to the Special Issue Soil Quality and Ecosystem)
Open AccessArticle Climate, Management and Habitat Associations of Avian Fauna in Restored Wetlands of California’s Central Valley, USA
Diversity 2012, 4(4), 396-418; doi:10.3390/d4040396
Received: 3 September 2012 / Revised: 30 October 2012 / Accepted: 15 November 2012 / Published: 23 November 2012
Cited by 1 | PDF Full-text (503 KB) | HTML Full-text | XML Full-text
Abstract
The Wetlands Reserve Program (WRP) is one of several programs implemented by the United States Department of Agriculture to facilitate natural resource management on private lands. Since the WRP’s inception approximately 29,000 ha in California’s Central Valley (CCV) have been restored. However [...] Read more.
The Wetlands Reserve Program (WRP) is one of several programs implemented by the United States Department of Agriculture to facilitate natural resource management on private lands. Since the WRP’s inception approximately 29,000 ha in California’s Central Valley (CCV) have been restored. However until now, actual benefits of the program to wildlife have never been evaluated. Hydrology in the CCV has been heavily modified and WRP wetlands are managed primarily to support wintering waterfowl. We surveyed over 60 WRP easements in 2008 and 2009 to quantify avian use and categorized bird species into 11 foraging guilds. We detected over 200 bird species in 2008 and 119 species in 2009, which is similar to or higher than numbers observed on other managed sites in the same area. We found that actively managed WRP wetlands support more waterfowl than sites under low or intermediate management, which is consistent with intended goals. Despite reported water shortages, greater upland and un-restored acreage in the southern CCV, WRP wetlands support large numbers of waterfowl and shorebirds, particularly in the early fall months. This is probably due to the severe lack of alternative habitat such as wildlife friendly crops at appropriate stages of the migration cycle. Improved access to water resources for hydrological management would greatly enhance waterfowl use in the southern CCV. Full article
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Open AccessArticle The Challenge of Managing Marine Biodiversity: A Practical Toolkit for a Cartographic, Territorial Approach
Diversity 2012, 4(4), 419-452; doi:10.3390/d4040419
Received: 3 September 2012 / Revised: 8 October 2012 / Accepted: 6 November 2012 / Published: 23 November 2012
Cited by 14 | PDF Full-text (3522 KB) | HTML Full-text | XML Full-text
Abstract
An approach to the management of marine biodiversity was developed based on two levels of environmental diagnostics: (1) the characterization (to identify types), and (2) the evaluation (to define status and values). Both levels involve the production of maps, namely: (i) morphobathymetry [...] Read more.
An approach to the management of marine biodiversity was developed based on two levels of environmental diagnostics: (1) the characterization (to identify types), and (2) the evaluation (to define status and values). Both levels involve the production of maps, namely: (i) morphobathymetry and sedimentology; (ii) habitats; (iii) natural emergencies; (iv) degradation and risk; (v) weighted vulnerability; (vi) environmental quality; and, (vii) susceptibility to use. A general methodological aspect that must be stated first is the need of dividing the mapped area in territorial units corresponding to submultiples of the UTM grid and having different sizes according to the scale adopted. Territorial units (grid cells) are assigned to one of five classes of evaluation, ranging from high necessity of conservation or protection to non-problematic, unimportant or already compromised (according to the specific map) situations. Depending on the scale, these maps are suited for territorial planning (small scales, allowing for a synoptic view) or for administration and decision making (large scales, providing detail on local situations and problems). Mapping should be periodically repeated (diachronic cartography) to assure an efficient tool for integrated coastal zone management. Full article
Open AccessArticle Aboveground Deadwood Deposition Supports Development of Soil Yeasts
Diversity 2012, 4(4), 453-474; doi:10.3390/d4040453
Received: 16 October 2012 / Revised: 27 November 2012 / Accepted: 4 December 2012 / Published: 10 December 2012
Cited by 9 | PDF Full-text (342 KB) | HTML Full-text | XML Full-text
Abstract
Unicellular saprobic fungi (yeasts) inhabit soils worldwide. Although yeast species typically occupy defined areas on the biome scale, their distribution patterns within a single type of vegetation, such as forests, are more complex. In order to understand factors that shape soil yeast [...] Read more.
Unicellular saprobic fungi (yeasts) inhabit soils worldwide. Although yeast species typically occupy defined areas on the biome scale, their distribution patterns within a single type of vegetation, such as forests, are more complex. In order to understand factors that shape soil yeast communities, soils collected underneath decaying wood logs and under forest litter were analyzed. We isolated and identified molecularly a total of 25 yeast species, including three new species. Occurrence and distribution of yeasts isolated from these soils provide new insights into ecology and niche specialization of several soil-borne species. Although abundance of typical soil yeast species varied among experimental plots, the analysis of species abundance and community composition revealed a strong influence of wood log deposition and leakage of organic carbon. Unlike soils underneath logs, yeast communities in adjacent areas harbored a considerable number of transient (phylloplane-related) yeasts reaching 30% of the total yeast quantity. We showed that distinguishing autochthonous community members and species transient in soils is essential to estimate appropriate effects of environmental factors on soil fungi. Furthermore, a better understanding of species niches is crucial for analyses of culture-independent data, and may hint to the discovery of unifying patterns of microbial species distribution. Full article
(This article belongs to the Special Issue Soil Quality and Ecosystem)
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Review

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Open AccessReview Enhancing Soil Quality and Plant Health Through Suppressive Organic Amendments
Diversity 2012, 4(4), 475-491; doi:10.3390/d4040475
Received: 26 November 2012 / Revised: 5 December 2012 / Accepted: 10 December 2012 / Published: 14 December 2012
Cited by 14 | PDF Full-text (276 KB) | HTML Full-text | XML Full-text
Abstract
The practice of adding organic amendments to crop soils is undergoing resurgence as an efficient way to restore soil organic matter content and to improve soil quality. The quantity and quality of the organic matter inputs affect soil physicochemical properties and soil [...] Read more.
The practice of adding organic amendments to crop soils is undergoing resurgence as an efficient way to restore soil organic matter content and to improve soil quality. The quantity and quality of the organic matter inputs affect soil physicochemical properties and soil microbiota, influencing different parameters such as microbial biomass and diversity, community structure and microbial activities or functions. The influence of organic amendments on soil quality has also effects on crop production and plant health. The enhancement of soil suppressiveness using organic amendments has been widely described, especially for soil-borne diseases. However, there is great variability in the effectiveness of suppression depending on the nature of the amendment, the crop, the pathogen, and the environmental conditions. Although the effects of organic amendments on soil properties have been widely studied, relationships between these properties and soil suppressiveness are not still well understood. Changes in soil physicochemical parameters may modulate the efficacy of suppression. However, the parameters more frequently associated to disease suppression appear to be related to soil microbiota, such as microbial biomass and activity, the abundance of specific microbial groups and some hydrolytic activities. This review focuses on the effect of organic amendments on soil microbial populations, diversity and activities; their ability to enhance plant health through disease suppression; and which of the parameters affected by the organic amendments are potentially involved in soil suppressiveness. Full article
(This article belongs to the Special Issue Soil Quality and Ecosystem)

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