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Deuterated water absorbed by deep roots of Artemisia tridentata appeared in the stem water of neighboring Agropyron desertorum tussocks. This supports the hypothesis that water absorbed by deep roots in moist soil moves through the roots, is released in the upper soil profile at night, and is stored there until it is resorbed by roots the following day. This phenomenon is termed hydraulic lift. The potential for parasitism of the water stored in the upper soil layers by neighboring plant roots is also shown. The effectiveness of water absorption by deep roots was substantially improved with hydraulic lift as indicated by reductions of 25 to 50% in transpiration on days following experimental circumvention of hydraulic...
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1 Univariate, multivariate, and geostatistical techniques were used to quantify the scale and degree of soil variability around individual perennial sagebrush (Artemisia tridentata ssp. vaseyana) and bluebunch wheatgrass (Pseudoroegneria spicata ssp. spicata) plants. This variability was then compared to that found across the larger sagebrush-steppe site. Samples were taken every metre in a 10-m $\times$ 12-m grid and every 12.5 cm in nine nested 0.5-m $\times$ 0.5-m grids containing at least one Artemisia shrub or Pseudoroegneria tussock (362 total samples). The 11 soil properties measured were organic matter, pH, water content, live root mass, microbial respiration, net N mineralization, nitrification potential,...
Water use and carbon acquisition were examined in a northern Utah population of Juniperus osteosperma (Torr.) Little. Leaf-level carbon assimilation, which was greatest in the spring and autumn, was limited by soil water availability. Gas exchange, plant water potential and tissue hydrogen stable isotopic ratio (deltaD) data suggested that plants responded rapidly to summer rain events. Based on a leaf area index of 1.4, leaf-level water use and carbon acquisition scaled to canopy-level means of 0.59 mm day(-1) and 0.13 mol m(-2) ground surface day(-1), respectively. Patterns of soil water potential indicated that J. osteosperma dries the soil from the surface downward to a depth of about 1 m. Hydraulic redistribution...
Hydraulic redistribution, the movement of water from soil layers of higher water potential to layers of lower water potential through the root systems of plants, has been documented in many taxa worldwide. Hydraulic redistribution is influenced principally by physical properties of roots and soils, and it should occur whenever root systems span soil layers of different water potential. Therefore, hydraulic redistribution should occur through the root systems of plants with aboveground tissue removed or through the root systems of fully senesced plants as long as roots remain intact and hydrated. We examined our hypothesis in field and greenhouse studies with the annual grass Bromus tectorum. We used soil psychrometry...
The aridland shrub species, Artemisia tridentata (big sagebrush) and Chrysothamnus nauseosus (rubber rabbitbrush), are distributed widely in the Intermountain region of western North America. Earlier research indicated that A. tridentata can utilize upper soil water from transient summer rain events while C. nauseosus apparently cannot, although both species have similar rooting depths. Thus, we hypothesized that C. nauseosus relies more on deep water than A. tridentata, while A. tridentata can take advantage of soil moisture in upper soil layers. We examined this hypothesis by growing A. tridentata and C. nauseosus in two-layer pots in which soil water content in the upper and lower layers was controlled independently....
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Common generalizations concerning the ecologic significance of C4 photosynthesis were tested in a study of plant gas exchange, productivity, carbon balance, and water use in monospecific communities of C3 and C4 salt desert shrubs. Contrary to expectations, few of the hypotheses concerning the performance of C4 species were supported. Like the C3 species, Ceratoides lanata, the C4 shrub, Atriplex confertifolia, initiated growth and photosynthetic activity in the cool spring months and also exhibited maximum photosynthetic rates at this time of year. To compete successfully with C3 species, Atriplex may have been forced to evolve the capacity for photosynthesis at low temperatures prevalent during the spring when...
An experiment was conducted to determine if growth and biomass responsesof the annual grass Bromus tectorum are affected by themagnitude and timing of nitrogen (N) pulses and if these responses areinfluenced by different perennial neighbor species. Nitrogen(NH4:NO3) was applied in three pulse treatments of varyinginterpulse length (3-d, 9-d, or 21-d between N additions). The total amount of Nadded was the same among treatments; hence, both the frequency and magnitude ofN pulses varied (i.e., the longer the interpulse period,the greater the amount of N added for a single pulse).Bromus showed little response to the different N-pulsetreatments. The only characteristic that varied among pulse treatments wasspecific...
Resources in the Great Basin of western North America often occur in pulses, and plant species must rapidly respond to temporary increases in water and nutrients during the growing season. A field study was conducted to evaluate belowground responses of Artemisia tridentata and Agropyron desertorum, common Great Basin shrub and grass species, respectively, to simulated 5-mm (typical summer rain) and 15-mm (large summer rain) summer rainfall events. The simulated rainfall was labeled with K15NO3 so that timing of plant nitrogen uptake could be monitored. In addition, soil NH4+ and NO3m concentrations and physiological uptake capacities for NO3m and NH4+were determined before and after the rainfall events. Root growth...
Categories: Publication; Types: Citation, Journal Citation; Tags: Oecologia
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Periodic collections of Atriplex confertifolia and Eurotia lanata leaf tissue throughout the growing season were analyzed for osmotic potential, water content, and concentration of Na+, K+, soluble Ca++, Cl-, and SO4 -- ions. Ionic concentrations of these two species exhibited marked similarities to corresponding values for European members of the same genera. Atriplex confertifolia, like many other Atriplex species, behaves as an alkali halophyte and accumulates Na+, while E. lanata appears to favor accumulation of K+ as did its European counterpart, E. ceratoides. The analyses showed a much broader range of tissue moisture contents and osmotic potentials during the season for Atriplex than for Eurotia. The differences...
Categories: Publication; Types: Citation, Journal Citation; Tags: Oecologia
Gas exchange studies were carried out on Artemisia tridentata during the course of a growing season using microclimatically controlled cuvettes and infrared gas analysis. A definite seasonal pattern of net photosynthesis emerged. This pattern was influenced by the interaction of four major factors: plant water potential, leaf temperature, irradiation, and stage of phenological development. In spring and early summer, when plant water stress was minimal, photosynthesis rate was mainly correlated with leaf temperature and irradiation. During mid and late summer, increased plant water stress and phenological changes assumed at least equal importance with temperature and irradiation in limiting net photosynthesis. Indeed,...
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Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring–fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our...
The temporal patterns of soil water potential in a stand of Artemisia tridentata in central Utah, USA, were monitored during the summer, which included small periodic rainfall events, and over the winter, when most of the soil recharge occurs in this environment. The pattern of recharge, when compared to an area cleared of aboveground vegetation, strongly indicated that the downward movement of water to 1.5 m was primarily conducted via roots by the process known as hydraulic redistribution. Rainwater was moved rapidly downward shortly after the rain event and continued over a period of a few days. For rainwater reaching a 0.3–1.5 m depth, the portion redistributed by roots was estimated to range from 100% for...
    map background search result map search result map Carbon balance, productivity, and water use of cold-winter desert shrub communities dominated by C3 and C4 species Seasonal pattern of net photosynthesis of Artemisia tridentata Geostatistical Patterns of Soil Heterogeneity Around Individual Perennial Plants Global change and biological soil crusts: effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions Hydraulic Redistribution through the Root Systems of Senesced Plants Rapid soil moisture recharge to depth by roots in a stand of Artemisia tridentata Carbon acquisition and water use in a Northern Utah Juniperus osteosperma (Utah juniper) population. Root responses and nitrogen acquisition by Artemisia tridentata and Agropyron desertorum following small summer rainfall events Gas exchange and growth responses of the desert shrubs Artemisia tridentata and Chrysothamnus nauseosus to shallow- vs. deep-soil water in a glasshouse experiment Mineral ion composition and osmotic relations of Atriplex confertifolia and Eurotia lanata Effects of perennial neighbors and nitrogen pulses on growth and nitrogen uptake by Bromus tectorum Geostatistical Patterns of Soil Heterogeneity Around Individual Perennial Plants Global change and biological soil crusts: effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions Carbon balance, productivity, and water use of cold-winter desert shrub communities dominated by C3 and C4 species Mineral ion composition and osmotic relations of Atriplex confertifolia and Eurotia lanata