共查询到20条相似文献,搜索用时 15 毫秒
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Constanza M. Montealegre Chris Van Kessel † Jürg M. Blumenthal ‡ Hor-Gil Hur Ueli A. Hartwig§ Michael J. Sadowsky¶ 《Global Change Biology》2000,6(5):475-482
An increase in concentration of atmospheric CO2 is one major factor influencing global climate change. Among the consequences of such an increase is the stimulation of plant growth and productivity. Below‐ground microbial processes are also likely to be affected indirectly by rising atmospheric CO2 levels, through increased root growth and rhizodeposition rates. Because changes in microbial community composition might have an impact on symbiotic interactions with plants, the response of root nodule symbionts to elevated atmospheric CO2 was investigated. In this study we determined the genetic structure of 120 Rhizobium leguminosarum bv. trifolii isolates from white clover plants exposed to ambient (350 μmol mol?1) or elevated (600 μmol mol?1) atmospheric CO2 concentrations in the Swiss FACE (Free‐Air‐Carbon‐Dioxide‐Enrichment) facility. Polymerase Chain Reaction (PCR) fingerprinting of genomic DNA showed that the isolates from plants grown under elevated CO2 were genetically different from those isolates obtained from plants grown under ambient conditions. Moreover, there was a 17% increase in nodule occupancy under conditions of elevated atmospheric CO2 when strains of R. leguminosarum bv. trifolii isolated from plots exposed to CO2 enrichment were evaluated for their ability to compete for nodulation with those strains isolated from ambient conditions. These results indicate that a shift in the community composition of R. leguminosarum bv. trifolii occurred as a result of an increased atmospheric CO2 concentration, and that elevated atmospheric CO2 affects the competitive ability of root nodule symbionts, most likely leading to a selection of these particular strains to nodulate white clover. 相似文献
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We measured soil CO2 flux over 19 sampling periods that spanned two growing seasons in a grassland Free Air Carbon dioxide Enrichment (FACE) experiment that factorially manipulated three major anthropogenic global changes: atmospheric carbon dioxide (CO2) concentration, nitrogen (N) supply, and plant species richness. On average, over two growing seasons, elevated atmospheric CO2 and N fertilization increased soil CO2 flux by 0.57 µmol m?2 s?1 (13% increase) and 0.37 µmol m?2 s?1 (8% increase) above average control soil CO2 flux, respectively. Decreases in planted diversity from 16 to 9, 4 and 1 species decreased soil CO2 flux by 0.23, 0.41 and 1.09 µmol m?2 s?1 (5%, 8% and 21% decreases), respectively. There were no statistically significant pairwise interactions among the three treatments. During 19 sampling periods that spanned two growing seasons, elevated atmospheric CO2 increased soil CO2 flux most when soil moisture was low and soils were warm. Effects on soil CO2 flux due to fertilization with N and decreases in diversity were greatest at the times of the year when soils were warm, although there were no significant correlations between these effects and soil moisture. Of the treatments, only the N and diversity treatments were correlated over time; neither were correlated with the CO2 effect. Models of soil CO2 flux will need to incorporate ecosystem CO2 and N availability, as well as ecosystem plant diversity, and incorporate different environmental factors when determining the magnitude of the CO2, N and diversity effects on soil CO2 flux. 相似文献
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Elevated atmospheric CO2 increases fine root production, respiration, rhizosphere respiration and soil CO2 efflux in Scots pine seedlings 总被引:2,自引:0,他引:2
IVAN. A. JANSSENS MEG. CROOKSHANKS† GAIL. TAYLOR† REINHART CEULEMANS 《Global Change Biology》1998,4(8):871-878
In this study, we investigated the impact of elevated atmospheric CO2 (ambient + 350 μmol mol–1) on fine root production and respiration in Scots pine (Pinus sylvestris L.) seedlings. After six months exposure to elevated CO2, root production measured by root in-growth bags, showed significant increases in mean total root length and biomass, which were more than 100% greater compared to the ambient treatment. This increased root length may have lead to a more intensive soil exploration. Chemical analysis of the roots showed that the roots in the elevated treatment accumulated more starch and had a lower C/N-ratio. Specific root respiration rates were significantly higher in the elevated treatment and this was probably attributed to increased nitrogen concentrations in the roots. Rhizospheric respiration and soil CO2 efflux were also enhanced in the elevated treatment. These results clearly indicate that under elevated atmospheric CO2 root production and development in Scots pine seedlings is altered and respiratory carbon losses through the root system are increased. 相似文献
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1 This research was conducted at the Aspen FACE (Free Air CO2 Enrichment) site located in northern Wisconsin, U.S.A. where trembling aspen (Populus tremuloides Michaux) trees were exposed to one of four atmospheric treatments: elevated carbon dioxide (CO2; 560 µL/L), elevated ozone (O3; ambient × 1.5), elevated CO2 and O3, or ambient air. We evaluated the effects of these fumigants on aspen foliar quality and the performance of aspen blotch leafminer (Phyllonorycter tremuloidiella Braun). 2 CO2 and O3 each affected foliar quality, with the major changes consisting of an 11% reduction in nitrogen under elevated CO2 and a 20% reduction in tremulacin under elevated O3. In the CO2 + O3 treatment, nitrogen levels were reduced by 15% and CO2 ameliorated the O3‐mediated reduction in tremulacin levels. 3 Phyllonorycter tremuloidiella were allowed to colonize trees naturally. Elevated CO2 and O3 reduced colonization rates by 42 and 49% relative to ambient CO2 and O3, respectively. The only effect of fumigation treatments on larval performance occurred under elevated O3, where male development time and larval consumption increased by 8 and 28%, respectively, over insects reared under ambient O3. 4 These data demonstrate that the individual and combined effects of CO2 and O3 can alter aspen foliar chemistry and that these alterations in foliar chemistry produce little to no change in larval performance. However, both CO2 and O3 greatly reduced oviposition. In order to ascertain the full effects of CO2 and O3 on insect performance, future studies should address both population‐ and individual‐level characteristics. 相似文献
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S. G. PRITCHARD C. M. PETERSON S. A. PRIOR H. H. ROGERS 《Plant, cell & environment》1997,20(4):461-471
The response of forest species to increasing atmospheric CO2, particularly under resource limitations, will require study in order to predict probable changes which may occur at the plant, community and ecosystem levels. Longleaf pine (Pinus palustris Mill.) seedlings were grown for 20 months at two levels of CO2 (365 and 720 μol mol1) in two levels of soil nitrogen (4 and 40 g m?2), and with two levels of soil moisture (–0·5 and –1·5 MPa xylem pressure potential). Leaf tissue was collected in the spring (12 months exposure) and autumn (20 months exposure) and examined using transmission electron microscopy (TEM) and light microscopy. During early spring, elevated CO2 magnified effects of N and water treatment on starch accumulation and in some cases contributed to altered organization of mesophyll chloroplasts. Disruption of chloroplast integrity was pronounced under elevated CO2, low N and water stress. In autumn, needles contained little starch; however, chloroplasts grown under high CO2 exhibited stress symptoms including increased plastoglobuli and shorter grana. A trend for reduced needle phloem cross-sectional area resulting from fewer sieve cells was also observed under elevated CO2. These results suggest that, in nature, longleaf pine seedlings may not benefit from a doubling of CO2, especially when soil resources are limiting. 相似文献
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Terrestrial ecosystems respond to an increased concentration of atmospheric CO2 . While elevated atmospheric CO2 has been shown to alter plant growth and productivity, it also affects ecosystem structure and function by changing below-ground processes. Knowledge of how soil microbiota respond to elevated atmospheric CO2 is of paramount importance for understanding global carbon and nutrient cycling and for predicting changes at the ecosystem-level. An increase in the atmospheric CO2 concentration not only alters the weight, length, and architecture of plant roots, but also affects the biotic and abiotic environment of the root system. Since the concentration of CO2 in soil is already 10–50 times higher than that in the atmosphere, it is unlikely that increasing atmospheric CO2 will directly influence the rhizosphere. Rather, it is more likely that elevated atmospheric CO2 will affect the microbe–soil–plant root system indirectly by increasing root growth and rhizodeposition rates, and decreasing soil water deficit. Consequently, the increased amounts and altered composition of rhizosphere-released materials will have the potential to alter both population and community structure, and activity of soil- and rhizosphere-associated microorganisms. This occurrence could in turn affect plant health and productivity and plant community structure. This review covers current knowledge about the response of soil microbes to elevated concentrations of atmospheric CO2 . 相似文献
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James I. L. Morison 《The New phytologist》2001,149(2):154-156
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There is approximately 50 times more inorganic carbon in the global ocean than in the atmosphere. On time scales of decades to millions of years, the interaction between these two geophysical fluids determines atmospheric CO2 levels. During glacial periods, for example, the ocean serves as the major sink for atmospheric CO2, while during glacial–interglacial transitions, it is a source of CO2 to the atmosphere. The mechanisms responsible for determining the sign of the net exchange of CO2 between the ocean and the atmosphere remain unresolved. There is evidence that during glacial periods, phytoplankton primary productivity increased, leading to an enhanced sedimentation of particulate organic carbon into the ocean interior. The stimulation of primary production in glacial episodes can be correlated with increased inputs of nutrients limiting productivity, especially aeolian iron. Iron directly enhances primary production in high nutrient (nitrate and phosphate) regions of the ocean, of which the Southern Ocean is the most important. This trace element can also enhance nitrogen fixation, and thereby indirectly stimulate primary production throughout the low nutrient regions of the central ocean basins. While the export flux of organic carbon to the ocean interior was enhanced during glacial periods, this process does not fully account for the sequestration of atmospheric CO2. Heterotrophic oxidation of the newly formed organic carbon, forming weak acids, would have hydrolyzed CaCO3 in the sediments, increasing thereby oceanic alkalinity which, in turn, would have promoted the drawdown of atmospheric CO2. This latter mechanism is consistent with the stable carbon isotope pattern derived from air trapped in ice cores. The oceans have also played a major role as a sink for up to 30% of the anthropogenic CO2 produced during the industrial revolution. In large part this is due to CO2 solution in the surface ocean; however, some, poorly quantified fraction is a result of increased new production due to anthropogenic inputs of combined N, P and Fe. Based on ‘circulation as usual’, models predict that future anthropogenic CO2 inputs to the atmosphere will, in part, continue to be sequestered in the ocean. Human intervention (large-scale Fe fertilization; direct CO2 burial in the deep ocean) could increase carbon sequestration in the oceans, but could also result in unpredicted environmental perturbations. Changes in the oceanic thermohaline circulation as a result of global climate change would greatly alter the predictions of C sequestration that are possible on a ‘circulation as usual’ basis. 相似文献
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Elevated atmospheric CO2 stimulates aboveground biomass in a fire-regenerated scrub-oak ecosystem 总被引:2,自引:0,他引:2
Paul Dijkstra Graham Hymus Debra Colavito David A. Vieglais† Christina M. Cundari‡ David P. Johnson Bruce A. Hungate§ C. ROSS Hinkle‡ Bert G. Drake 《Global Change Biology》2002,8(1):90-103
The effect of elevated atmospheric CO2 concentration (Ca) on the aboveground biomass of three oak species, Quercus myrtifolia, Q. geminata, and Q. chapmanii, was estimated nondestructively using allometric relationships between stem diameter and aboveground biomass after four years of experimental treatment in a naturally fire‐regenerated scrub‐oak ecosystem. After burning a stand of scrub‐oak vegetation, re‐growing plants were exposed to either current ambient (379 µL L?1 CO2) or elevated (704 µL L?1 CO2) Ca in 16 open‐top chambers over a four‐year period, and measurements of stem diameter were carried out annually on all oak shoots within each chamber. Elevated Ca significantly increased aboveground biomass, expressed either per unit ground area or per shoot; elevated Ca had no effect on shoot density. The relative effect of elevated Ca on aboveground biomass increased each year of the study from 44% (May 96–Jan 97), to 55% (Jan 97–Jan 98), 66% (Jan 98–Jan 99), and 75% (Jan 99–Jan 00). The effect of elevated Ca was species specific: elevated Ca significantly increased aboveground biomass of the dominant species, Q. myrtifolia, and tended to increase aboveground biomass of Q. chapmanii, but had no effect on aboveground biomass of the subdominant, Q. geminata. These results show that rising atmospheric CO2 has the potential to stimulate aboveground biomass production in ecosystems dominated by woody species, and that species‐specific growth responses could, in the long term, alter the composition of the scrub‐oak community. 相似文献
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Root-derived CO2 efflux via xylem stream rivals soil CO2 efflux 总被引:2,自引:2,他引:0
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Elevated atmospheric CO2 alters stomatal responses to variable sunlight in a C4 grass 总被引:1,自引:1,他引:0
Native tallgrass prairie in NE Kansas was exposed to elevated (twice ambient) or ambient atmospheric CO2 levels in open-top chambers. Within chambers or in adjacent unchambered plots, the dominant C4 grass, Andropogon gerardii, was subjected to fluctuations in sunlight similar to that produced by clouds or within canopy shading (full sun > 1500 μmol m−2 s−1 versus 350 μmol m−2 s−1 shade) and responses in gas exchange were measured. These field experiments demonstrated that stomatal conductance in A. gerardii achieved new steady state levels more rapidly after abrupt changes in sunlight at elevated CO2 when compared to plants at ambient CO2. This was due primarily to the 50% reduction in stomatal conductance at elevated CO2, but was also a result of more rapid stomatal responses. Time constants describing stomatal responses were significantly reduced (29–33%) at elevated CO2. As a result, water loss was decreased by as much as 57% (6.5% due to more rapid stomatal responses). Concurrent increases in leaf xylem pressure potential during periods of sunlight variability provided additional evidence that more rapid stomatal responses at elevated CO2 enhanced plant water status. CO2-induced alterations in the kinetics of stomatal responses to variable sunlight will likely enhance direct effects of elevated CO2 on plant water relations in all ecosystems. 相似文献
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Sensing of atmospheric CO2 by plants 总被引:15,自引:12,他引:3
K. A. MOTT 《Plant, cell & environment》1990,13(7):731-737
Abstract. Despite recent interest in the effects of high CO2 on plant growth and physiology, very little is known about the mechanisms by which plants sense changes in the concentration of this gas. Because atmospheric CO2 concentration is relatively constant and because the conductance of the cuticle to CO2 is low, sensory mechanisms are likely to exist only for intercellular CO2 concentration. Therefore, responses of plants to changes in atmospheric CO2 will depend on the effect of these changes on intercellular CO2 concentration. Although a variety of plant responses to atmospheric CO2 concentration have been reported, most of these can be attributed to the effects of intercellular CO2 on photosynthesis or stomatal conductance. Short-term and long-term effects of CO2 on photosynthesis and stomatal conductance are discussed as sensory mechanisms for responses of plants to atmospheric CO2 . Available data suggest that plants do not fully realize the potential increases in productivity associated with increased atmospheric CO2 . This may be because of genetic and environmental limitations to productivity or because plant responses to CO2 have evolved to cope with variations in intercellular CO2 caused by factors other than changes in atmospheric CO2 . 相似文献
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Elevated atmospheric CO2 effects on biomass production and soil carbon in conventional and conservation cropping systems 总被引:1,自引:0,他引:1
Stephen A. Prior G. Brett Runion Hugo H. Rogers H. Allen Torbert D. Wayne Reeves† 《Global Change Biology》2005,11(4):657-665
Increasing atmospheric CO2 concentration has led to concerns about potential effects on production agriculture as well as agriculture's role in sequestering C. In the fall of 1997, a study was initiated to compare the response of two crop management systems (conventional and conservation) to elevated CO2. The study used a split‐plot design replicated three times with two management systems as main plots and two CO2 levels (ambient=375 μL L?1 and elevated CO2=683 μL L?1) as split‐plots using open‐top chambers on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudults). The conventional system was a grain sorghum (Sorghum bicolor (L.) Moench.) and soybean (Glycine max (L.) Merr.) rotation with winter fallow and spring tillage practices. In the conservation system, sorghum and soybean were rotated and three cover crops were used (crimson clover (Trifolium incarnatum L.), sunn hemp (Crotalaria juncea L.), and wheat (Triticum aestivum L.)) under no‐tillage practices. The effect of management on soil C and biomass responses over two cropping cycles (4 years) were evaluated. In the conservation system, cover crop residue (clover, sunn hemp, and wheat) was increased by elevated CO2, but CO2 effects on weed residue were variable in the conventional system. Elevated CO2 had a greater effect on increasing soybean residue as compared with sorghum, and grain yield increases were greater for soybean followed by wheat and sorghum. Differences in sorghum and soybean residue production within the different management systems were small and variable. Cumulative residue inputs were increased by elevated CO2 and conservation management. Greater inputs resulted in a substantial increase in soil C concentration at the 0–5 cm depth increment in the conservation system under CO2‐enriched conditions. Smaller shifts in soil C were noted at greater depths (5–10 and 15–30 cm) because of management or CO2 level. Results suggest that with conservation management in an elevated CO2 environment, greater residue amounts could increase soil C storage as well as increase ground cover. 相似文献
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1 Broad beans (Vicia faba L.) were grown at either ambient (350 μL/L) or elevated (700 μL/L) CO2. Elevated CO2 increased shoot weight by 14% and root weight by 24% compared to ambient, but did not affect flowering. 2 A single pea aphid (Acyrthosiphon pisum (Harris)) and its progeny decreased shoot and root weights by 20 and 24%, respectively, at ambient CO2 after 20 days, but did not affect flower number. At elevated CO2A. pisum decreased shoot and root weights by 27 and 34% and flower number decreased by 73%. 3 A single glasshouse and potato aphid (Aulacorthum solani (Kaltenbach)) and its progeny had no effect on the growth of bean plants after 20 days at ambient CO2. At elevated CO2, A. solani decreased shoot and root weights by 20 and 18%, and flower number by 60%. 4 The large reduction in flowering caused by aphids at elevated CO2 suggests a change in resource allocation within the plants to compensate for aphid infestation. 5 Aphid density was unaffected by elevated CO2, although there were significant effects of CO2 on the resulting population structure of both A. pisum and A solani. We suggest that at elevated CO2, aphids appear not to achieve their maximum reproductive potential and their populations are limited by the lower carrying capacity of their host plants. 相似文献
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J. L. Lutze J. S. Roden C. J. Holly J. Wolfe J. J. G. Egerton & M. C. Ball 《Plant, cell & environment》1998,21(6):631-635
Growth under elevated [CO2 ] promoted spring frost damage in field grown seedlings of snow gum ( Eucalyptus pauciflora Sieb. ex Spreng.), one of the most frost tolerant of eucalypts. Freezing began in the leaf midvein, consistent with it being a major site of frost damage under field conditions. The average ice nucleation temperature was higher in leaves grown under elevated [CO2 ] (– 5·7 °C versus – 4·3 °C), consistent with the greater incidence of frost damage in these leaves (34% versus 68% of leaves damaged). These results have major implications for agriculture, forestry and vegetation dynamics, as an increase in frost susceptibility may reduce potential gains in productivity from CO2 fertilization and may affect predictions of vegetation change based on increasing temperature. 相似文献