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These data represent simulated soil temperature and moisture conditions for current climate, and for future climate represented by all available climate models at two time periods during the 21st century. These data were used to: 1) quantify the direction and magnitude of expected changes in several measures of soil temperature and soil moisture, including the key variables used to distinguish the regimes used in the R and R categories; 2) assess how these changes will impact the geographic distribution of soil temperature and moisture regimes; and 3) explore the implications for using R and R categories for estimating future ecosystem resilience and resistance.
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Temporal and spatial sources of silica for chert remain poorly constrained. Modern sources to the worlds oceans include silica in rivers > aeolian (dust) deposition > sea floor vents and submarine weathering. However, changes in aridity and dust flux during the Phanerozoic may explain variations in the ocean silica cycle and times and places of chert formation. The chemistry of fine quartz dust (FQD) provides a chemical mechanism for the transformation of FQD to polymorphs of silica in chert; FQD is readily dissolved, then reprecipitated as Opal-A by either biotic or abiotic processes. An unequivocal relation between increases in dust flux and biogenic opal-A in the western Pacific Ocean during the past 200 kyr...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/eap.1389/full): Woody plant encroachment and overall declines in perennial vegetation in dryland regions can alter ecosystem properties and indicate land degradation, but the causes of these shifts remain controversial. Determining how changes in the abundance and distribution of grass and woody plants are influenced by conditions that regulate water availability at a regional scale provides a baseline to compare how management actions alter the composition of these vegetation types at a more local scale and can be used to predict future shifts under climate change. Using a remote-sensing-based approach, we assessed the balance between grasses and woody plants...
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This dataset includes the cover of perennial grasses in 1989, 1995, 1999, 2005, and 2009 across southern Arizona. Cover was determined using sub-pixel classifications of two Landsat scenes from path 36, row 38 (centered on latitude: 31.7470, longitude: -111.3981) and path 37, row 38 (31.7470, -112.9431) that encompass Tucson, AZ.
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Woody plant encroachment and overall declines in perennial vegetation in dryland regions can alter ecosystem properties and indicate land degradation, but the causes of these shifts remain controversial. Determining how changes in the abundance and distribution of grass and woody plants are influenced by conditions that regulate water availability at a regional scale provides a baseline to which compare how management actions alter the composition of these vegetation types at a more local scale and can be used to predict future shifts under climate change. Using a remote sensing-based approach, we assessed the balance between grasses and woody plants and how climate and topo-edaphic conditions affected their abundances...
Aim: To test the hypothesis that anthropogenic alteration of stream-flow regimes is a key driver of compositional shifts from native to introduced riparian plant species. Location: The arid south-western United States; 24 river reaches in the Gila and Lower Colorado drainage basins of Arizona. Methods: We compared the abundance of three dominant woody riparian taxa (native Populus fremontii and Salix gooddingii, and introduced Tamarix) between river reaches that varied in stream-flow permanence (perennial vs. intermittent), presence or absence of an upstream flow-regulating dam, and presence or absence of municipal effluent as a stream water source. Results: Populus and Salix were the dominant pioneer trees along...
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This dataset includes the cover of leguminous trees (Prosopis velutina, Parkinsonia microphylla, Parkinsonia florida) in 1989, 1995, 1999, 2005, and 2009 across southern Arizona. Cover was determined using sub-pixel classifications of two Landsat scenes from path 36, row 38 (centered on latitude: 31.7470, longitude: -111.3981) and path 37, row 38 (31.7470, -112.9431) that encompass Tucson, AZ.
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This dataset includes the cover of creosote bush (Larrea tridentata)in 1989, 1995, 1999, 2005, and 2009 across southern Arizona. Cover was determined using sub-pixel classifications of two Landsat scenes from path 36, row 38 (centered on latitude: 31.7470, longitude: -111.3981) and path 37, row 38 (31.7470, -112.9431) that encompass Tucson, AZ.


    map background search result map search result map Data for Decadal shifts in grass and woody plant cover are driven by prolonged drying and modified by topo-edaphic properties Shifts in Perennial grass in southern Arizona, 1989 - 2009 Shifts in Creosote bush in southern Arizona, 1989 - 2009 Shifts in Leguminous tree in southern Arizona, 1989 - 2009 The chemistry of eolian quartz dust and the origin of chert Historical and 21st century soil temperature and moisture data for drylands of western U.S. and Canada Data for Decadal shifts in grass and woody plant cover are driven by prolonged drying and modified by topo-edaphic properties Shifts in Perennial grass in southern Arizona, 1989 - 2009 Shifts in Creosote bush in southern Arizona, 1989 - 2009 Shifts in Leguminous tree in southern Arizona, 1989 - 2009 Historical and 21st century soil temperature and moisture data for drylands of western U.S. and Canada The chemistry of eolian quartz dust and the origin of chert