ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

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Electronic Resource

Scaling metabolism from organisms to ecosystems (2003)

Economo, Evan P. ; Huxman, Travis E. ; Allen, Andrew P. ; [et al.]

[s.l.] : Macmillian Magazines Ltd.

Nature 423 (2003), S. 639-642

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] Understanding energy and material fluxes through ecosystems is central to many questions in global change biology and ecology. Ecosystem respiration is a critical component of the carbon cycle and might be important in regulating biosphere response to global climate change. Here we derive a ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/nature01671

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2

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Convergence across biomes to a common rain-use efficiency (2004)

Fay, Philip A. ; Knapp, Alan K. ; Shaw, M. Rebecca ; [et al.]

[s.l.] : Macmillian Magazines Ltd.

Nature 429 (2004), S. 651-654

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] Water availability limits plant growth and production in almost all terrestrial ecosystems. However, biomes differ substantially in sensitivity of aboveground net primary production (ANPP) to between-year variation in precipitation. Average rain-use efficiency (RUE; ANPP/precipitation) also ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/nature02561

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3

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Elevated CO 2 increases productivity and invasive species success in an arid ecosystem (2000)

Huxman, Travis E. ; Zitzer, Stephen F. ; Charlet, Therese N. ; [et al.]

[s.l.] : Macmillian Magazines Ltd.

Nature 408 (2000), S. 79-82

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] Arid ecosystems, which occupy about 20% of the earth's terrestrial surface area, have been predicted to be one of the most responsive ecosystem types to elevated atmospheric CO2 and associated global climate change. Here we show, using free-air CO2 enrichment (FACE) ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/35040544

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4

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Photosynthetic responses of Mojave Desert shrubs to free air CO2 enrichment are greatest during wet years (2003)

Naumburg, Elke ; Housman, David C. ; Huxman, Travis E. ; [et al.]

Oxford, UK : Blackwell Science, Ltd

Global change biology 9 (2003), S. 0

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ISSN: 1365-2486

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography

Notes: It has been suggested that desert vegetation will show the strongest response to rising atmospheric carbon dioxide due to strong water limitations in these systems that may be ameliorated by both photosynthetic enhancements and reductions in stomatal conductance. Here, we report the long-term effect of 55 Pa atmospheric CO2 on photosynthesis and stomatal conductance for three Mojave Desert shrubs of differing leaf phenology (Ambrosia dumosa—drought-deciduous, Krameria erecta—winter-deciduous, Larrea tridentata—evergreen). The shrubs were growing in an undisturbed ecosystem fumigated using FACE technology and were measured over a four-year period that included both above and below-average precipitation. Daily integrated photosynthesis (Aday) was significantly enhanced by elevated CO2 for all three species, although Krameria erecta showed the greatest enhancements (63% vs. 32% for the other species) enhancements were constant throughout the entire measurement period. Only one species, Larrea tridentata, decreased stomatal conductance by 25–50% in response to elevated CO2, and then only at the onset of the summer dry season and following late summer convective precipitation. Similarly, reductions in the maximum carboxylation rate of Rubisco were limited to Larrea during spring. These results suggest that the elevated CO2 response of desert vegetation is a function of complex interactions between species functional types and prevailing environmental conditions. Elevated CO2 did not extend the active growing season into the summer dry season because of overall negligible stomatal conductance responses that did not result in significant water conservation. Overall, we expect the greatest response of desert vegetation during years with above-average precipitation when the active growing season is not limited to ∼2 months and, consequently, the effects of increased photosynthesis can accumulate over a biologically significant time period.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00580.x

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5

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Functional ecology of shrub seedlings after a natural recruitment event at the Nevada Desert FACE Facility (2003)

HOUSMAN, DAVID C. ; ZITZER, STEPHEN F. ; HUXMAN, TRAVIS E. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Global change biology 9 (2003), S. 0

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ISSN: 1365-2486

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography

Notes: Seedling recruitment is an important determinant of community structure in desert ecosystems. Positive photosynthetic growth and water balance responses to increasing atmospheric carbon dioxide (CO2) concentrations ([CO2]) are predicted to be substantial in desert plants, suggesting that recruitment could be stimulated. However, to date no studies have addressed the response of perennial plant recruitment in natural populations of desert shrubs exposed to elevated [CO2]. In April 1997, we employed Free-Air Carbon Dioxide Enrichment (FACE) in order to increase atmospheric [CO2] in an undisturbed Mojave Desert ecosystem from ambient (∼∼ 370 µmol mol−1) to elevated CO2 (∼∼ 550 µmol mol−1). From 1997 to 2001 we seasonally examined survival, growth, gas exchange and water potential responses of Larrea tridentata and Ambrosia dumosa seedlings that germinated in Fall, 1997. Recruitment densities were not influenced by [CO2] in either species, although a two-fold higher adult Ambrosia density under elevated [CO2] resulted in two-fold higher seedling density (0.87 vs 0.40 seedlings m−2). Mortality was greatest for both species during the first summer (1998), despite above-average rainfall during the previous Winter–Spring. A significant [CO2] × time interaction revealed that early survival was greater under elevated CO2, whereas a significant species time interaction revealed that overall survival was greater for Ambrosia (28%) than for Larrea (15%), regardless of [CO2]. Microsite (understorey or interspace) alone had no significant influence on survival. Significant species, microsite and species × microsite effects on growth (seedling height, stem diameter and canopy size) were found, but elevated CO2 had minimal impact on these parameters. Photosynthetic rates (Asat) for both species were higher at elevated [CO2] during certain seasons, but not consistently so. These results suggest that increased atmospheric [CO2] may enhance carbon (C) assimilation and survival of aridland perennial shrubs during favourable growing conditions, but that it may not counteract the effects of prolonged drought on mortality.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00618.x

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6

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The effects of parental CO2 environment on seed quality and subsequent seedling performance in Bromusrubens (1998)

Huxman, Travis E. ; Hamerlynck, Erik P. ; Jordan, Dean N. ; [et al.]

Springer

Oecologia 114 (1998), S. 202-208

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ISSN: 1432-1939

Keywords: Key wordsBromusrubens ; Mojave Desert ; Elevated CO2 ; C/N ratio ; Maternal effects

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Seeds were collected and compared from parent plants of Bromusrubens L. (Poaceae), an exotic Mojave Desert annual grass, grown in ambient (360 μmol mol−1) and elevated (700 μmol mol−1) CO2 to determine if parental CO2 growth conditions affected seed quality. Performance of seeds developed on the above plants was evaluated to determine the influence of parental CO2 growth conditions on germination, growth rate, and leaf production. Seeds of B. rubens developed on parents grown in elevated CO2 had a larger pericarp surface area, higher C:N ratio, and less total mass than ambient-developed seeds. Parental CO2 environment did not have an effect on germination percentage or mean germination time, as determined by radicle emergence. Seedlings from elevated-CO2-developed seeds had a reduced relative growth rate and achieved smaller final mass over the same growth period. Elevated-CO2-developed seeds had smaller seed reserves than ambient seeds, as determined by growing seedlings in sterile media and monitoring senescence. It appears that increased seed C:N ratios associated with plants grown under elevated CO2 may have a major effect on seed quality (morphology, nutrition) and seedling performance (e.g., growth rate and leaf production). Since the invasive success of B. rubens is primarily due to its ability to rapidly germinate, increase leaf area and maintain a relatively high growth rate compared to native annuals and perennial grasses, reductions in seed quality and seedling performance in elevated CO2 may have significant impacts on future community composition in the Mojave Desert.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050437

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7

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Effects of extreme high temperature, drought and elevated CO2 on photosynthesis of the Mojave Desert evergreen shrub, Larrea tridentata (2000)

Hamerlynck, Erik P. ; Huxman, Travis E. ; Loik, Michael E. ; [et al.]

Springer

Plant ecology 148 (2000), S. 183-193

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ISSN: 1573-5052

Keywords: Chlorophyll fluorescence ; Drought ; Elevated CO2 ; High temperature ; Larrea tridenata ; Photosynthesis

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The interaction of extreme temperature events with future atmospheric CO2 concentrations may have strong impacts on physiological performance of desert shrub seedlings, which during the critical establishment phase often endure temperature extremes in conjunction with pronounced drought. To evaluate the interaction of drought and CO2 on photosynthesis during heat stress, one-year-old Larrea tridentata[DC] Cov. seedlings were exposed to nine days of heat with midday air temperature maxima reaching 53 °C under three atmospheric CO2 concentrations (360, 550 and 700 μmol mol−1) and two water regimes (well-watered and droughted). Photosynthetic gas exchange, chlorophyll fluorescence and water potential responses were measured prior to, during and one week following the high temperature stress event. Heat stress markedly decreased net photosynthetic rate (A net), stomatal conductance (g s), and the photochemical efficiency of photosystem II (F v/F m) in all plants except for well-watered L. tridentata grown in 700 μmol mol−1 CO2. A net and g s remained similar to pre-stress levels in these plants. In droughted L. tridentata, A net was ca. 2× (in 550 μmol mol−1 CO2) to 3× (in 700 μmol mol−1 CO2) higher than in ambient-CO2-grown plants, while g s and F v/F m were similar and low in all CO2 treatments. Following heat stress, g s in all well-watered plants rose dramatically, exceeding pre-stress levels by up to 100%. In droughted plants, g s and A net rose only in plants grown at elevated CO2 following release from heat. This recovery response was strongest at 700 μmol mol−1 CO2, which returned to A net and g s values similar to pre-heat following several days of recovery. Extreme heat diminished the photosynthetic down-regulation response to growth at elevated CO2 under well-watered conditions, similar to the action of drought. Ambient-CO2-grown L. tridentata did not show significant recovery of photosynthetic capacity (A \max and CE) after alleviation of temperature stress, especially when exposed to drought, while plants exposed to elevated CO2 appeared to be unaffected. These findings suggest that elevated CO2 could promote photosynthetic activity during critical periods of seedling establishment, and enhance the potential for L. tridentata to survive extreme high temperature events.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009896111405

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Temperature sensitivity of drought-induced tree mortality portends increased regional die-off under global-change-type drought (2009)

Adams, Henry D. ; Guardiola-Claramonte, Maite ; Barron-Gafford, Greg A. ; [et al.]

National Academy of Sciences

In: PNAS - Proceedings of the National Academy of Sciences of the United States of America. 2009; 106(17): 7063-7066. Published 2009 Apr 13. doi: 10.1073/pnas.0901438106.

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Publication Date: 2009-04-13

Description: Large-scale biogeographical shifts in vegetation are predicted in response to the altered precipitation and temperature regimes associated with global climate change. Vegetation shifts have profound ecological impacts and are an important climate-ecosystem feedback through their alteration of carbon, water, and energy exchanges of the land surface. Of particular concern is the potential for warmer temperatures to compound the effects of increasingly severe droughts by triggering widespread vegetation shifts via woody plant mortality. The sensitivity of tree mortality to temperature is dependent on which of 2 non-mutually-exclusive mechanisms predominates—temperature-sensitive carbon starvation in response to a period of protracted water stress or temperature-insensitive sudden hydraulic failure under extreme water stress (cavitation). Here we show that experimentally induced warmer temperatures (≈4 °C) shortened the time to drought-induced mortality in Pinus edulis (piñon shortened pine) trees by nearly a third, with temperature-dependent differences in cumulative respiration costs implicating carbon starvation as the primary mechanism of mortality. Extrapolating this temperature effect to the historic frequency of water deficit in the southwestern United States predicts a 5-fold increase in the frequency of regional-scale tree die-off events for this species due to temperature alone. Projected increases in drought frequency due to changes in precipitation and increases in stress from biotic agents (e.g., bark beetles) would further exacerbate mortality. Our results demonstrate the mechanism by which warmer temperatures have exacerbated recent regional die-off events and background mortality rates. Because of pervasive projected increases in temperature, our results portend widespread increases in the extent and frequency of vegetation die-off.

Print ISSN: 0027-8424

Electronic ISSN: 1091-6490

Topics: Biology , Medicine , Natural Sciences in General