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Elevated CO2 and temperature impacts on different components of soil CO2 efflux in Douglas-fir terracosms (1999)

Lin, Guanghui ; Ehleringer, James R. ; Rygiewicz, PauL. T. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Global change biology 5 (1999), 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: Although numerous studies indicate that increasing atmospheric CO2 or temperature stimulate soil CO2 efflux, few data are available on the responses of three major components of soil respiration [i.e. rhizosphere respiration (root and root exudates), litter decomposition, and oxidation of soil organic matter] to different CO2 and temperature conditions. In this study, we applied a dual stable isotope approach to investigate the impact of elevated CO2 and elevated temperature on these components of soil CO2 efflux in Douglas-fir terracosms. We measured both soil CO2 efflux rates and the 13C and 18O isotopic compositions of soil CO2 efflux in 12 sun-lit and environmentally controlled terracosms with 4-year-old Douglas fir seedlings and reconstructed forest soils under two CO2 concentrations (ambient and 200 ppmv above ambient) and two air temperature regimes (ambient and 4 °C above ambient). The stable isotope data were used to estimate the relative contributions of different components to the overall soil CO2 efflux. In most cases, litter decomposition was the dominant component of soil CO2 efflux in this system, followed by rhizosphere respiration and soil organic matter oxidation. Both elevated atmospheric CO2 concentration and elevated temperature stimulated rhizosphere respiration and litter decomposition. The oxidation of soil organic matter was stimulated only by increasing temperature. Release of newly fixed carbon as root respiration was the most responsive to elevated CO2, while soil organic matter decomposition was most responsive to increasing temperature. Although some assumptions associated with this new method need to be further validated, application of this dual-isotope approach can provide new insights into the responses of soil carbon dynamics in forest ecosystems to future climate changes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00211.x

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2

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Effects of climate change on labile and structural carbon in Douglas-fir needles as estimated by δ13C and Carea measurements (2002)

HOBBIE, ERIC A. ; GREGG, JILLIAN ; OLSZYK, DAVID M. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Global change biology 8 (2002), 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: Models of photosynthesis, respiration, and export predict that foliar labile carbon (C) should increase with elevated CO2 but decrease with elevated temperature. Sugars, starch, and protein can be compared between treatments, but these compounds make up only a fraction of the total labile pool. Moreover, it is difficult to assess the turnover of labile carbon between years for evergreen foliage. Here, we combined changes in foliar Carea (C concentration on an areal basis) as needles aged with changes in foliar isotopic composition (δ13C) caused by inputs of 13C-depleted CO2 to estimate labile and structural C in needles of different ages in a four-year, closed-chamber mesocosm experiment in which Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were exposed to elevated temperature (ambient + 3.5 °C) and CO2 (ambient + 179 ppm). Declines in δ13C of needle cohorts as they aged indicated incorporation of newly fixed labile or structural carbon. The δ13C calculations showed that new C was 41 ± 2% and 28 ± 3% of total needle carbon in second- and third-year needles, respectively, with higher proportions of new C in elevated than ambient CO2 chambers (e.g. 42 ± 2% vs. 37 ± 6%, respectively, for second-year needles). Relative to ambient CO2, elevated CO2 increased labile C in both first- and second-year needles. Relative to ambient temperature, elevated temperature diminished labile C in second-year needles but not in first-year needles, perhaps because of differences in sink strength between the two needle age classes. We hypothesize that plant-soil feedbacks on nitrogen supply contributed to higher photosynthetic rates under elevated temperatures that partly compensated for higher turnover rates of labile C. Strong positive correlations between labile C and sugar concentrations suggested that labile C was primarily determined by carbohydrates. Labile C was negatively correlated with concentrations of cellulose and protein. Elevated temperature increased foliar %C, possibly due to a shift of labile constituents from low %C carbohydrates to relatively high %C protein. Decreased sugar concentrations and increased nitrogen concentrations with elevated temperature were consistent with this explanation. Because foliar constituents that vary in isotopic signature also vary in concentrations with leaf age or environmental conditions, inferences of ci/ca values from δ13C of bulk leaf tissue should be done cautiously. Tracing of 13C through foliar carbon pools may provide new insight into foliar C constituents and turnover.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2486.2002.00541.x

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3

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Elevated CO2 and temperature alter nitrogen allocation in Douglas-fir (2003)

TINGEY, DAVID T. ; MCKANE, ROBERT B. ; OLSZYK, DAVID M. ; [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: The effects of elevated CO2 and temperature on principal carbon constituents (PCC) and C and N allocation between needle, woody (stem and branches) and root tissue of Pseudotsuga menziesii Mirb. Franco seedlings were determined. The seedlings were grown in sun-lit controlled-environment chambers that contained a native soil. Chambers were controlled to reproduce ambient or ambient +180 ppm CO2 and either ambient temperature or ambient +3.5 °C for 4 years. There were no significant CO2 × temperature interactions; consequently the data are presented for the CO2 and temperature effects. At the final harvest, elevated CO2 decreased the nonpolar fraction of the PCC and increased the polar fraction and amount of sugars in the needles. In contrast, elevated temperature increased the nonpolar fraction of the PCC and decreased sugars in needles. There were no CO2 or temperature effects on the PCC fractions in the woody tissue or root tissue. Elevated CO2 and temperature had no significant effects on the C content of any of the plant tissues or fractions. In contrast, the foliar N content declined under elevated CO2 and increased under elevated temperature; there were no significant effects in other tissues. The changes in the foliar N concentrations were in the cellulose and lignin fractions, the fractions, which contain protein, and are the consequences of changes in N allocation under the treatments. These results indicate reallocation of N among plant organs to optimize C assimilation, which is mediated via changes in the selectivity of Rubisco and carbohydrate modulation of gene expression.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00646.x

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4

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Mycorrhizae alter quality and quantity of carbon allocated below ground (1994)

Rygiewicz, Paul T. ; Andersen, Christian P.

[s.l.] : Nature Publishing Group

Nature 369 (1994), S. 58-60

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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] Ectomycorrhizae are one form of fungus-root symbioses whose morphological characteristics include a root enclosed in a sheath of fungal tissue and a complex network of hyphae between root epidermal and cortical cells that extends into the soil2'3. The intimate morphology extends the surface area ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/369058a0

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5

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A root-mycocosm for growing ectomycorrhizal hyphae apart from host roots while maintaining symbiotic integrity (1988)

Rygiewicz, Paul T. ; Miller, Steven L. ; Durall, Daniel M.

Springer

Plant and soil 109 (1988), S. 281-284

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ISSN: 1573-5036

Keywords: culture system ; ectomycorrhizae ; extramatrical hyphae ; Hebeloma crustuliniforme ; hyphal mass ; in vitro physiology ; ponderosa pine ; Root-Mycocosm ; synthesis

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract A culture system is described to grow mycorrhizal plants which allows experimental measurements to be made on mycorrhizae, and a portion of intact ectomycorrhizal fungi while in symbiosis, but growing apart from the rooting medium and host roots. A portion of the extramatrical hyphae is kept apart from the rooting medium by a restrictive passageway between the root and fungal chambers. The passageway is small enough to restrict coniferous fine roots to the root chamber, but large enough to allow fungal hyphae to grow out of the root chamber onto pre-weighed glass fiber filter paper situated in the fungal chambers. The pre-weighed filter paper allows for gravimetric estimation of the hyphal mass in the fungal chamber. The pieces of the modular Root-Mycocosm can be assembled in various configurations with one or two seedling chambers and one, two or three fungal chambers. Ponderosa pine (Pinus ponderosa Laws.) seedlings were inoculated withHebeloma crustuliniforme (Bull.: St. Amans) Qúel in either commercial-vermiculite inoculum or in plastic growth-pouches and grown in the Root-Mycocosm. Hyphae were allowed to grow into the fungal chambers and after four weeks, amounted to 5.5±0.81 SE and 6.4±1.5 SE mg for pouch and commercial inoculum techniques, respectively.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02202096

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6

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Lifetime and temporal occurrence of ectomycorrhizae on ponderosa pine (Pinus ponderosa Laws.) seedlings grown under varied atmospheric CO2 and nitrogen levels (1997)

Rygiewicz, Paul T. ; Johnson, Mark G. ; Ganio, Lisa M. ; [et al.]

Springer

Plant and soil 189 (1997), S. 275-287

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ISSN: 1573-5036

Keywords: atmospheric carbon dioxide ; climate change ; minirhizotron tubes ; mycorrhizal root tips ; nitrogen fertilization

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Climate change (elevated atmospheric CO2, and altered air temperatures, precipitation amounts and seasonal patterns) may affect ecosystem processes by altering carbon allocation in plants, and carbon flux from plants to soil. Mycorrhizal fungi, as carbon sinks, are among the first soil biota to receive carbon from plants, and thereby influence carbon release from plants to soil. One step in this carbon release is via fine root and mycorrhizal turnover. It is necessary to know the lifetime and temporal occurrence of roots and mycorrhizae to determine the capacity of the soil ecosystem to sequester carbon assimilated aboveground. In this study, ponderosa pine (Pinus ponderosa Laws) seedlings were grown under three levels of atmospheric CO2 (ambient, 525 and 700 μmol CO2 mol-1) and three levels of annual nitrogen additions (0,100 and 200 kg N ha-1) in open-top chambers. At a two-month frequency during 18 months, we observed ectomycorrhizal root tips observed using minirhizotron tubes and camera. The numbers of new mycorrhizal root tips, the numbers of tips that disappeared between two consecutive recording events, and the standing crop of tips at each event were determined. There were more mycorrhizal tips of all three types seen during the summer compared with other times of the year. When only the standing crop of mycorrhizal tips was considered, effects of the CO2 and N addition treatments on carbon allocation to mycorrhizal tips was weakly evident. However, when the three types of tips were considered collectively, tips numbers flux of carbon through mycorrhizae was greatest in the: (1) high CO2 treatment compared with the other CO2 treatments, and (2) intermediate N addition treatment compared with the other N addition treatments. A survival analysis on the entire 18 month cohort of tips was done to calculate the median lifetime of the mycorrhizal root tips. Average median lifetime of the mycorrhizal tips was 139 days and was not affected by nitrogen and CO2 treatments.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004210709108

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7

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Restriction fragment length polymorphisms distinguish ectomycorrhizal fungi (1989)

Armstrong, John L. ; Fowles, Nanci L. ; Rygiewicz, Paul T.

Springer

Plant and soil 116 (1989), S. 1-7

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ISSN: 1573-5036

Keywords: ectomycorrhizal fungi ; endonuclease ; isolate identification ; RFLP ; restriction fragment length polymorphism ; rDNA

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Basidiomycetous fungi, two saprophytes and three mycorrhizal, were used to assess the specificity of DNA hybridization for distinguishing genera from one another. Interspecific comparisons were done with several isolates of mycorrhizal fungi,Laccaria bicolor andL. laccata, collected from diverse geographical sites. The DNAs were digested with four restriction nucleases and separated by gel electrophoresis into patterns of DNA fragments called restriction fragment length polymorphisms (RFLPs). The RFLPs were hybridized with a radioactively-labeled DNA probe encoding Basidiomycetous ribosomal RNA genes. The five genera were discernable using both unprobed and probed RFLPs. Hybridization of probe DNA with RFLPs was isolate-specific for all nine Laccaria isolates examined. The reclassification of aL. bicolor isolate is supported, demonstrating that hybridization of RFLPs offers an additional tool for taxonomy of ectomycorrhizal fungi. The method may have field application for distinguishing known isolates if their DNA fingerprints are previously ascertained and are distinct from RFLPs of indigenous organisms.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02327250

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