Moisture Relationships in Twelve Northern Desert Shrub Communities Near Grand Junction, Colorado

Branson, F. A.; Miller, R. F.; McQueen, I. S.

doi:10.2307/1935039

Cited by 69 publications

(34 citation statements)

References 32 publications

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“…Furthermore, the relatively small change in soil texture in the top 50 cm of soil indicates that moisture in the deeper soil layers plays a key role in annual and forb plant performance in these systems, as Hammerlynck et al (2002) found in their work. We note that evapotranspiration is positively associated with vegetation cover (Branson et al 1976). Therefore, greater vegetation cover and associated competition for water off dunes cannot be ruled out as additional factors associated with lower attained plant C off dunes.…”

Section: Plant and Soil Water Relationsmentioning

confidence: 73%

Plant Responses to an Edaphic Gradient across an Active Sand Dune/Desert Boundary in the Great Basin Desert

Rosenthal

Ludwig

Donovan

2005

International Journal of Plant Sciences

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In arid ecosystems, variation in precipitation causes broad-scale spatial heterogeneity in soil moisture, but differences in soil texture, development, and plant cover can also create substantial local soil moisture heterogeneity. The boundary between inland desert sand dunes and adjacent desert habitats exhibits abrupt changes in soil and vegetation characteristics that may be associated with differences in plant-available water and nutrients. We hypothesized that differences in plant water status between habitats would mirror changes in soil texture and vegetation cover. Because the dunes have higher water availability, we predicted that plants on dunes would have higher plant water potential (C) and be less water use efficient than plants off dunes. We tested these predictions for three species-Psoralidium lanceolatum (a C 3 perennial N-fixing subshrub), Stipa hymenoides (a C 3 perennial bunchgrass), and Salsola iberica (a C 4 annual)-on actively moving desert dunes and adjacent stabilized dunes at Little Sahara Dunes, Utah. Plants on the dunes maintained higher predawn (C pd ) water potentials (>ÿ1.5 MPa) throughout the summer season, whereas off-dune plants were water stressed from July on (C pd < ÿ1:5 MPa). Midday water potential (C md ) generally mirrored C pd . As predicted, off-dune plants were more water use efficient, on the basis of leaf carbon isotope ratios (d 13 C) for the C 3 species. The observed differences in soil particle size, soil water content, and the concomitant effect on soil C likely explain the observed differences in C pd . Soil N was significantly lower on dunes, while soil P was similar across habitats. In contrast, leaf N was similar across habitats, but leaf P was significantly higher on dunes, possibly because of species-specific differences in nutrient relations or differences in habitat nutrient availability. Abrupt changes in water and nutrient availability associated with soil texture are likely to be important selective forces shaping plants' strategies in this and other desert boundary communities.

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Section: Plant and Soil Water Relationsmentioning

confidence: 73%

Plant Responses to an Edaphic Gradient across an Active Sand Dune/Desert Boundary in the Great Basin Desert

Rosenthal

Ludwig

Donovan

2005

International Journal of Plant Sciences

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“…In contrast, the other sites are located closer to the floodplain, and thus roots likely have access to supplemental water, which could account for the overall lack of decline with increasing temperature. Sarcobatus vermiculatus was expected to be less sensitive to temperature than A. tridentata because it is a phreatophyte well adapted to hot desert regions and because it can drop leaves in the summer (Branson et al 1976). In contrast, A. tridentata has a low photosynthetic temperature optima and is at v www.esajournals.org the southern end of its distribution on the Colorado Plateau (Caldwell 1985).…”

Section: Shrublandsmentioning

confidence: 99%

On the brink of change: plant responses to climate on the Colorado Plateau

et al. 2011

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Abstract. The intensification of aridity due to anthropogenic climate change in the southwestern U.S. is likely to have a large impact on the growth and survival of plant species that may already be vulnerable to water stress. To make accurate predictions of plant responses to climate change, it is essential to determine the long-term dynamics of plant species associated with past climate conditions. Here we show how the plant species and functional types across a wide range of environmental conditions in Colorado Plateau national parks have changed with climate variability over the last twenty years. During this time, regional mean annual temperature increased by 0.188C per year from 1989-1995, 0.068C per year from 1995-2003, declined by 0.148C from [2003][2004][2005][2006][2007][2008], and there was high interannual variability in precipitation. Non-metric multidimensional scaling of plant species at long-term monitoring sites indicated five distinct plant communities. In many of the communities, canopy cover of perennial plants was sensitive to mean annual temperature occurring in the previous year, whereas canopy cover of annual plants responded to cool season precipitation. In the perennial grasslands, there was an overall decline of C 3 perennial grasses, no change of C 4 perennial grasses, and an increase of shrubs with increasing temperature. In the shrublands, shrubs generally showed no change or slightly increased with increasing temperature. However, certain shrub species declined where soil and physical characteristics of a site limited water availability. In the higher elevation woodlands, Juniperus osteosperma and shrub canopy cover increased with increasing temperature, while Pinus edulis at the highest elevation sites was unresponsive to interannual temperature variability. These results from well-protected national parks highlight the importance of temperature to plant responses in a water-limited region and suggest that projected increases in aridity are likely to promote grass loss and shrub expansion on the Colorado Plateau.

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“…There is some support for the wilting point values (h w ), which are the lowest matric potentials at which plant water withdrawal becomes zero. Sagebrush was reported to operate in soils with potentials as low as -7.0 MPa (Fernandez and Caldwell 1975;Branson et al 1976). Cline et al (1977) showed that cheatgrass could remove water at potentials as low as -1.5 MPa.…”

Section: C12mentioning

confidence: 99%

Performance Assessment

1999

International Oil Spill Conference Proceedings

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SummaryLockheed Martin Hanford Company (LMHC) is designing and assessing the performance of disposal facilities to receive radioactive wastes that are currently stored in single -and double -shell tanks at the Hanford Site. The preferred method of disposing of the portion that is classified as immobilized lowactivity waste (ILAW) is to vitrify the waste and place the product in near-surface, shallow-land burial facilities. The LMHC project to assess the performance of these disposal facilities is known as the Hanford ILAW Performance Assessment (PA) Activity, hereafter called the ILAW PA project. The goal of this project is to provide a reasonable expectation that the disposal of the waste is protective of the general public, groundwater resources, air resources, surface-water resources, and inadvertent intruders. Achieving this goal will require predictions of contaminant migration from the facility. To make such predictions will require estimates of the fluxes of water moving through the sediments within the vadose zone around and beneath the disposal facility. These fluxes, loosely called recharge rates, are the primary mechanism for transporting contaminants to the groundwater.Pacific Northwest National Laboratory (PNNL) assists LMHC in their performance assessment activities. One of the PNNL tasks is to provide estimates of recharge rates for current conditions and long-term scenarios involving the shallow-land disposal of ILAW. Specifically, recharge estimates are needed for a fully functional surface cover, the cover sideslope, and the immediately surrounding terrain. In addition, recharge estimates are needed for degraded cover conditions. The temporal scope of the analysis is 10,000 years, but could be longer if some contaminant peaks occur after 10,000 years.The elements of this report compose the Recharge Data Package, which provides estimates of recharge rates for the scenarios being considered in the 2001 PA. Table S.1 identifies the surface features and time periods evaluated. The most important feature, the surface cover, is expected to be the modified RCRA Subtitle C design. This design uses a 1-m-thick silt loam layer above sand and gravel filter layers to create a capillary break. A 0.15-m-thick asphalt layer underlies the filter layers to function as a backup barrier and to promote lateral drainage. Cover sideslopes are expected to be constructed with 1V:10H slopes using sandy gravel. The recharge estimates for each scenario were derived from lysimeter and tracer data collected by the ILAW PA and other projects and from modeling analyses.For the best estimate case, we proposed using a recharge rate of 0.1 mm/yr for the surface cover with a shrub-steppe plant community. This rate is lower than the cover design goal of 0.5 mm/yr because it is closer to the actual drainage rate measured with lysimeters and inferred with modeling. The simulation results showed that erosion of 20% of the silt loam layer did not impair this performance nor did the deposition of 20 cm of dune sand. For the sandy grav...

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Moisture Relationships in Twelve Northern Desert Shrub Communities Near Grand Junction, Colorado

Cited by 69 publications

References 32 publications

Plant Responses to an Edaphic Gradient across an Active Sand Dune/Desert Boundary in the Great Basin Desert

Plant Responses to an Edaphic Gradient across an Active Sand Dune/Desert Boundary in the Great Basin Desert

On the brink of change: plant responses to climate on the Colorado Plateau

Performance Assessment

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