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Nitrogen (N) is a critical limiting nutrient that regulates plant productivity and the cycling of other essential elements in forests. We measured foliar and soil nutrients in 22 young Douglas-fir stands in the Oregon Coast Range to examine patterns of nutrient availability across a gradient of N-poor to N-rich soils. N in surface mineral soil ranged from 0.15 to 1.05% N, and was positively related to a doubling of foliar N across sites. Foliar N in half of the sites exceeded 1.4% N, which is considered above the threshold of N-limitation in coastal Oregon Douglas-fir. Available nitrate increased five-fold across this gradient, whereas exchangeable magnesium (Mg) and calcium (Ca) in soils declined, suggesting that...
Categories: Publication; Types: Citation; Tags: Ecosystems
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This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the...
Categories: Publication; Types: Citation; Tags: Ecosystems
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This map layer shows Omernik's Level III ecoregions, derived from a 1:7,500,000 map created by J.M. Omernik in 1987 and from refinements of Omernik's framework that were made for other projects. Ecoregions describe areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. Omernik's ecoregions are based on the premise that a hierarchy of ecological regions can be identified through the analysis of the patterns and the composition of both living and nonliving phenomena, such as geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology, that affect or reflect differences in ecosystem quality and integrity. All the characteristics are considered...
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This metadata references the polygonal ARC/INFO GIS cover showing the current and historic distribution of potential habitat, or range, of the Greater Sage-grouse (Centrocercus urophasianus) and Gunnison Sage-grouse (Centrocercus minimus) in Western North America. This data was initially researched and compiled by Dr. Michael A. Schroeder, research biologist for the Washington State Department of Fish and Wildlife. The initial draft of current and historic range data was mapped and submitted to state, federal, or provincial natural resource agencies and other experts for review, comment, and editing. The final product represents the best available science and expert review available at the time of compilation. ...
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This dataset shows innundation from the terrestrial ecosystems (reference classification) of South America, Central America, and Mexico. South America: This dataset represents Ecological System patches using various reference datasets. Original data generarated from 2000 era data, modeled in 2005 and updated in 2008 and 2010.Originally, this project developed a GIS modeling approach, using a variety of abiotic and biotic data sets, to produce a map of the distribution of Latin America and Caribbean (LAC) ecological systems throughout South America for use in ecoregional assessments. Ecological systems, defined as spatially co-occuring assemblages of vegetation types sharing a common underlying substrate, ecological...
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This dataset was extracted from the terrestrial ecosystems of South America dataset. South America: This dataset represents Ecological System patches using various reference datasets. Original data generarated from 2000 era data, modeled in 2005 and updated in 2008 and 2010.Originally, this project developed a GIS modeling approach, using a variety of abiotic and biotic data sets, to produce a map of the distribution of Latin America and Caribbean (LAC) ecological systems throughout South America for use in ecoregional assessments. Ecological systems, defined as spatially co-occuring assemblages of vegetation types sharing a common underlying substrate, ecological process, or gradient, were identified for all...
Desert grasslands, which are very sensitive to external drivers like climate change, are areas affected by rapid land degradation processes. In many regions of the world the common form of land degradation involves the rapid encroachment of woody plants into desert grasslands. This process, thought to be irreversible and sustained by biophysical feedbacks of global desertification, results in the heterogeneous distribution of vegetation and soil resources. Most of these shrub-grass transition systems at the desert margins are prone to disturbances such as fires, which affect the interactions between ecological, hydrological, and land surface processes. Here we investigate the effect of prescribed fires on the landscape...


map background search result map search result map Omernik's Level III Ecoregions of the Continental United States Terrestrial Ecosystems of Latin America: Innundation (Level 3) Terrestrial Ecosystems (Reference Classification) of Chile Current Distribution of the Sage-grouse in North America Current Distribution of the Sage-grouse in North America Terrestrial Ecosystems (Reference Classification) of Chile Omernik's Level III Ecoregions of the Continental United States Terrestrial Ecosystems of Latin America: Innundation (Level 3)