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Life Sciences

2005

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University of Nebraska - Lincoln

Articles 61 - 69 of 69

Full-Text Articles in Physical Sciences and Mathematics

Fuel Reduction And Restoration Of Pine/Hardwood Ecosystems Severely Impacted By The Recent Southern Pine Beetle (Dendroctonus Frontalis) Epidemic In The Southern Appalachians, James M. Vose, Katherine J. Elliott Jan 2005

Fuel Reduction And Restoration Of Pine/Hardwood Ecosystems Severely Impacted By The Recent Southern Pine Beetle (Dendroctonus Frontalis) Epidemic In The Southern Appalachians, James M. Vose, Katherine J. Elliott

JFSP Research Project Reports

As a result of this most recent SPB epidemic (1999-2003), thousands of hectares of dead pine trees have created wildfire-hazard conditions in the southern Appalachians. One of the challenges for land managers is how to return fire to these ecosystems after (1) nearly a decade of exclusion, and (2) the more recent SPB mortality enhanced fuel loads. Higher fuel loads have the potential to increase fire intensity and severity. At the extremes, fires of high intensity and severity can have a large effect on ecosystem structure and function. The objectives of our research were: (1) to quantify fuel load reduction …

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Factors Affecting Regional Variation In Growth Of Channel Catfish, Bart W. Durham, Kevin L. Pope, Gene R. Wilde Jan 2005

Factors Affecting Regional Variation In Growth Of Channel Catfish, Bart W. Durham, Kevin L. Pope, Gene R. Wilde

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

We related the length at age of channel catfish Ictalurus punctatus, an indirect measure of growth, to three climatic and five morphoedaphic variables in 144 Texas reservoirs. Growth of channel catfish ages 3 through 6 was negatively related to longitude, a factor that explained as much as 34% of the variation in length at age. Channel catfish length at age was not significantly related to latitude, conductivity, morphoedaphic index, mean depth, and maximum depth in all age-classes. Among age-7 channel catfish, length at age was positively related to reservoir area, which explained 35% of the variation in growth. A …

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The Use Of Discontinuities And Functional Groups To Assess Relative Resilience In Complex Systems, Craig R. Allen, L. Gunderson, A. R. Johnson Jan 2005

The Use Of Discontinuities And Functional Groups To Assess Relative Resilience In Complex Systems, Craig R. Allen, L. Gunderson, A. R. Johnson

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

It is evident when the resilience of a system has been exceeded and the system qualitatively changed. However, it is not clear how to measure resilience in a system prior to the demonstration that the capacity for resilient response has been exceeded. We argue that self-organizing human and natural systems are structured by a relatively small set of processes operating across scales in time and space. These structuring processes should generate a discontinuous distribution of structures and frequencies, where discontinuities mark the transition from one scale to another. Resilience is not driven by the identity of elements of a system, …

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Marketing Locally Produced Foods: Consumer And Farmer Opinions In Washington County, Nebraska, Mindi L. Schneider, Charles A. Francis Jan 2005

Marketing Locally Produced Foods: Consumer And Farmer Opinions In Washington County, Nebraska, Mindi L. Schneider, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Local food system potentials were studied in Washington County, Nebraska, United States. As a departure from most studies of locally based systems, farmers were surveyed in addition to consumers for potential participation. Data about the current food system and opinions and preferences for local production, marketing, and purchasing of food were collected using self-administered mail questionnaires. The response rate was 35% for the farmer survey and 37% for the consumer survey. Results indicated that, on the farming side of the food system, conventional corn and soybean production and marketing predominated in Washington County, and farmer interest in producing for local …

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Science-Based Organic Farming 2005: Toward Local And Secure Food Systems, Charles A. Francis, Twyla Hansen, Peter Skelton Jan 2005

Science-Based Organic Farming 2005: Toward Local And Secure Food Systems, Charles A. Francis, Twyla Hansen, Peter Skelton

Publications from the Center for Applied Rural Innovation (CARI)

Organic farming includes growing food and fiber — animals, agronomic crops, horticultural fruits and vegetables, related products — as one dynamic and rapidly evolving component of our complex U.S. food system. Even as more farmers are moving toward organic certification and participation in an environmentally sound and economically lucrative market, questions arise about the long-term social impacts and sustainability of a set of practices that has gone from a movement to an industry. Consolidations in the organic trade have brought multinational corporations to the table, as they have observed a grassroots activity that has grown by 20% per year for …

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Ecology Of Soil Microarthropods In Gobi Gurvan Saykhan Mountains, Southern Mongolia, Tsedev Bolortuya, Badamdorj Bayartogtokh Jan 2005

Ecology Of Soil Microarthropods In Gobi Gurvan Saykhan Mountains, Southern Mongolia, Tsedev Bolortuya, Badamdorj Bayartogtokh

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

In the present paper, we describe the community structure, species diversity, population density, and the character of distribution of soil microarthropods of the Gobi Gurvan Saykhan mountains. In total 45 species of soil microarthropods belonging to 37 genera and 24 families were identified. Twenty-seven species of soil microarthropods belonging to 25 genera and 20 families were found in the Züün Saykhan, 31 species belonging to 27 genera and 19 families in the Dund Saykhan. Oribatid mites are the dominant group (35 species = 77.8% of total species richness), while mesostigmatid mites account for 7 species (15.6 %). Other groups are …

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Die Parasitierung Der Luzerne-Blattschneiderbiene, Megachile Rotundata (Hymenoptera: Megachilidae), Durch Physocephala Pusilla (Diptera: Conopidae) In Der Mongolei = Parasitization Of The Alfalfa Leaf-Cutter Bee, Megachile Rotundata (Hymenoptera: Megachilidae), By Physocephala Pusilla (Diptera: Conopidae) In Mongolia, Karsten Seidelmann Jan 2005

Die Parasitierung Der Luzerne-Blattschneiderbiene, Megachile Rotundata (Hymenoptera: Megachilidae), Durch Physocephala Pusilla (Diptera: Conopidae) In Der Mongolei = Parasitization Of The Alfalfa Leaf-Cutter Bee, Megachile Rotundata (Hymenoptera: Megachilidae), By Physocephala Pusilla (Diptera: Conopidae) In Mongolia, Karsten Seidelmann

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Physocephala pusilla Meigen (Diptera: Conopidae) was found to be a dangerous endoparasitoid of the alfalfa leafcutter bee Megachile rotundata F. (Hymenoptera: Megachilidae) in Mongolia. The conopid fly parasitizes adults and causes their early death. In 1989 and 1990, 16% and 15% respectively of the M. rotundata females were found dead in front of the bee shelter. However, the number of bees (females and males) dying in the field is unknown. These bees cause a contamination of the alfalfa fields due to an increase of the conopid population. Therefore, Ph. pusilla becomes a serious problem for the management of M. rotundata …

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Biodiversity And Ecology Of Soil Oribatid Mites (Acari: Oribatida) In The Grassland Habitats Of Eastern Mongolia, Badamdorj Bayartogtokh Jan 2005

Biodiversity And Ecology Of Soil Oribatid Mites (Acari: Oribatida) In The Grassland Habitats Of Eastern Mongolia, Badamdorj Bayartogtokh

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Composition, abundance, distribution, and diversity of oribatid mite communities were investigated at five study areas in Eastern Mongolia. A total of 88 species of oribatid mites were recorded from the studied areas. The largest number of species (51 spp.) was found in the habitats of river valleys, while the plain steppe which covers the largest area contained the lowest species richness (24 spp.). Three other sub-regions with similar landscape types show approximately the same species richness (39 to 45 spp.), although they are located relatively far from each other. The oribatid mite faunas of all sub-regions were essentially similar to …

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Types Of Areas And The Origin Of Black Flies Fauna In Mongolia (Diptera: Simuliidae), Josef Halgoš Jan 2005

Types Of Areas And The Origin Of Black Flies Fauna In Mongolia (Diptera: Simuliidae), Josef Halgoš

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

The survey of Mongolian Black Flies species (Diptera: Simuliidae) is given in the presented work. The classification based on Emelyanov (1974) and Gorodkov (1984) appeared to be as most advantageous one. Black Flies species found on the Mongolian territory up to now were classified according to the character of their distribution among 5 groups: Holoarctic species (7 species), Eurasian (15), Eastern Palaearctic (20), Turanian-Mediterranean (7), Mongolian endemic species (8). Individual groups are divided according to the type of area into smaller subgroups. The zoogeographical analysis has shown big similarity with Black Flies zoogeography in Siberia and Far East (in percentage …

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