Effect of Elevated CO2, O3, and UV Radiation on Soils

Science.gov (United States)

Rejšek, Klement; Vranová, Valerie

2014-01-01

In this work, we have attempted to review the current knowledge on the impact of elevated CO2, O3, and UV on soils. Elevated CO2 increases labile and stabile soil C pool as well as efficiency of organic pollutants rhizoremediation and phytoextraction of heavy metals. Conversely, both elevated O3 and UV radiation decrease inputs of assimilates to the rhizosphere being accompanied by inhibitory effects on decomposition processes, rhizoremediation, and heavy metals phytoextraction efficiency. Contrary to elevated CO2, O3, or UV-B decreases soil microbial biomass, metabolisable C, and soil Nt content leading to higher C/N of soil organic matter. Elevated UV-B radiation shifts soil microbial community and decreases populations of soil meso- and macrofauna via direct effect rather than by induced changes of litter quality and root exudation as in case of elevated CO2 or O3. CO2 enrichment or increased UV-B is hypothesised to stimulate or inhibit both plant and microbial competitiveness for soluble soil N, respectively, whereas O3 favours only microbial competitive efficiency. Understanding the consequences of elevated CO2, O3, and UV radiation for soils, especially those related to fertility, phytotoxins inputs, elements cycling, plant-microbe interactions, and decontamination of polluted sites, presents a knowledge gap for future research. PMID:24688424

Water relations and gas exchange in poplar and willow under water stress and elevated atmospheric CO2.

Science.gov (United States)

Johnson, Jon D; Tognetti, Roberto; Paris, Piero

2002-05-01

Predictions of shifts in rainfall patterns as atmospheric [CO2] increases could impact the growth of fast growing trees such as Populus spp. and Salix spp. and the interaction between elevated CO2 and water stress in these species is unknown. The objectives of this study were to characterize the responses to elevated CO2 and water stress in these two species, and to determine if elevated CO2 mitigated drought stress effects. Gas exchange, water potential components, whole plant transpiration and growth response to soil drying and recovery were assessed in hybrid poplar (clone 53-246) and willow (Salix sagitta) rooted cuttings growing in either ambient (350 &mgr;mol mol-1) or elevated (700 &mgr;mol mol-1) atmospheric CO2 concentration ([CO2]). Predawn water potential decreased with increasing water stress while midday water potentials remained unchanged (isohydric response). Turgor potentials at both predawn and midday increased in elevated [CO2], indicative of osmotic adjustment. Gas exchange was reduced by water stress while elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species. Dark respiration decreased in elevated [CO2] and water stress reduced Rd in the trees growing in ambient [CO2]. Willow had 56% lower whole plant hydraulic conductivity than poplar, and showed a 14% increase in elevated [CO2] while poplar was unresponsive. The physiological responses exhibited by poplar and willow to elevated [CO2] and water stress, singly, suggest that these species respond like other tree species. The interaction of [CO2] and water stress suggests that elevated [CO2] did mitigate the effects of water stress in willow, but not in poplar.

Elevated CO[sub 2] alters deployment of roots in small growth containers

Energy Technology Data Exchange (ETDEWEB)

Berntson, G M; McConnaughay, K D.M.; Bazzaz, F A [Harvard University, Cambridge, MA (United States). Dept. of Organismic and Evolutionary Biology

1993-07-01

Previously the authors examined how limited rooting space and nutrient supply influenced plant growth under elevated atmospheric CO[sub 2] concentrations. To gain insight into how elevated CO[sub 2] atmospheres affect how plants utilize available belowground space, when rooting space and nutrient supply are limited, they measured the deployment of roots within pots through time. Contrary to aboveground responses, patterns of belowground deployment were most strongly influenced by elevated CO[sub 2] in pots of different volume and shape. Further, elevated CO[sub 2] conditions interacted differently with limited belowground space for the two species studied, Abutilon theophrasti, a C[sub 3] dicot with a deep taproot, and Setaria faberii, a C4 monocot with a shallow fibrous root system. For Setaria, elevated CO[sub 2] increased the size of the largest region of low root density at the pot surface in larger rooting volumes independent of nutrient content, thereby decreasing their efficiency of deployment. For Abutilon, plants responded to elevated CO[sub 2] concentrations by equalizing the pattern of deployment in all the pots. Nutrient concentration, and not pot size or shape, greatly influenced the density of root growth. Root densities for Abutilon and Setaria were similar to those observed in field conditions, for annual dicots and monocots respectively, suggesting that studies using pots may successfully mimic natural conditions.

The Interactive Effects of Elevated CO2 and Ammonium Enrichment on the Physiological Performances of Saccharina japonica (Laminariales, Phaeophyta)

Science.gov (United States)

Kang, Jin Woo; Chung, Ik Kyo

2018-04-01

Environmental challenges such as ocean acidification and eutrophication influence the physiology of kelp species. We investigated their interactive effects on Saccharina japonica (Laminariales, Phaeophyta) under two pH conditions [Low, 7.50; High (control), 8.10] and three NH4 +concentrations (Low, 4; Medium, 60; High, 120 μM). The degree of variation of pH values in the culture medium and inhibition rate of photosynthetic oxygen evolution by acetazolamide were affected by pH treatments. Relative growth rates, carbon, nitrogen, and the C:N ratio in tissue samples were influenced by higher concentrations of NH4 + . Rates of photosynthetic oxygen evolution were enhanced under elevated CO2 or NH4 +conditions, independently, but these two factors did not show an interactive effect. However, rates of NH4 +uptake were influenced by the interactive effect of increased CO2 under elevated NH4 +treatment. Although ocean acidification and eutrophication states had an impact on physiological performance, chlorophyll fluorescence was not affected by those conditions. Our results indicated that the physiological reactions by this alga were influenced to some extent by a rise in the levels of CO2 and NH4 + . Therefore, we expect that the biomass accumulation of S. japonica may well increase under future scenarios of ocean acidification and eutrophication.

Forest succession at elevated CO2; TOPICAL

International Nuclear Information System (INIS)

Clark, James S.; Schlesinger, William H.

2002-01-01

We tested hypotheses concerning the response of forest succession to elevated CO2 in the FACTS-1 site at the Duke Forest. We quantified growth and survival of naturally recruited seedlings, tree saplings, vines, and shrubs under ambient and elevated CO2. We planted seeds and seedlings to augment sample sites. We augmented CO2 treatments with estimates of shade tolerance and nutrient limitation while controlling for soil and light effects to place CO2 treatments within the context of natural variability at the site. Results are now being analyzed and used to parameterize forest models of CO2 response

Elevated [CO2] does not ameliorate the negative effects of elevated temperature on drought-induced mortality in Eucalyptus radiata seedlings.

Science.gov (United States)

Duan, Honglang; Duursma, Remko A; Huang, Guomin; Smith, Renee A; Choat, Brendan; O'Grady, Anthony P; Tissue, David T

2014-07-01

It has been reported that elevated temperature accelerates the time-to-mortality in plants exposed to prolonged drought, while elevated [CO(2)] acts as a mitigating factor because it can reduce stomatal conductance and thereby reduce water loss. We examined the interactive effects of elevated [CO(2)] and temperature on the inter-dependent carbon and hydraulic characteristics associated with drought-induced mortality in Eucalyptus radiata seedlings grown in two [CO(2)] (400 and 640 μL L(-1)) and two temperature (ambient and ambient +4 °C) treatments. Seedlings were exposed to two controlled drying and rewatering cycles, and then water was withheld until plants died. The extent of xylem cavitation was assessed as loss of stem hydraulic conductivity. Elevated temperature triggered more rapid mortality than ambient temperature through hydraulic failure, and was associated with larger water use, increased drought sensitivities of gas exchange traits and earlier occurrence of xylem cavitation. Elevated [CO(2)] had a negligible effect on seedling response to drought, and did not ameliorate the negative effects of elevated temperature on drought. Our findings suggest that elevated temperature and consequent higher vapour pressure deficit, but not elevated [CO(2)], may be the primary contributors to drought-induced seedling mortality under future climates. © 2013 John Wiley & Sons Ltd.

Rangeland -- plant response to elevated CO2

International Nuclear Information System (INIS)

Owensby, C.E.; Coyne, P.I.; Ham, J.M.; Parton, W.; Rice, C.; Auen, L.M.; Adam, N.

1993-01-01

Plots of a tallgrass prairie ecosystem were exposed to ambient and twice-ambient CO 2 concentrations in open-top chambers and compared to unchambered ambient CO 2 plots during the entire growing season from 1989 through 1992. Relative root production among treatments was estimated using root ingrowth bags which remained in place throughout the growing season. Latent heat flux was simulated with and without water stress. Botanical composition was estimated annuallyin all treatments. Open-top chambers appeared to reduce latent heat flux and increase water use efficiency similar to elevated CO 2 when water stress was not severe, but under severe water stress, chamber effect on water use efficiency was limited. In natural ecosystems with periodic moisture stress, increased water use efficiency under elevated CO 2 apparently would have a greater impact on productivity than photosynthetic pathway. Root ingrowth biomass was greater in 1990 and 1991 on elevated CO 2 plots compared to ambient or chambered-ambient plots. In 1992, there was no difference in root ingrowth biomass among treatments

Effects of decadal exposure to interacting elevated CO2 and/or O3 on paper birch (Betula papyrifera) reproduction

International Nuclear Information System (INIS)

Darbah, Joseph N.T.; Kubiske, Mark E.; Nelson, Neil; Oksanen, Elina; Vapaavuori, Elina; Karnosky, David F.

2008-01-01

We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO 2 and/or O 3 on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO 2 increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O 3 also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO 2 + O 3 ) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO 2 may have a largely positive impact on forest tree reproduction and regeneration while elevated O 3 will likely have a negative impact. - In this study, we found that elevated CO 2 enhances and elevated O 3 decreases birch reproduction and early seedling growth

IMPACTS OF INTERACTING ELEVATED ATMOSPHERIC CO2 AND O3 ON THE STRUCTURE AND FUNCTIONING OF A NORTHERN FOREST ECOSYSTEM: OPERATING AND DECOMMISSIONING THE ASPEN FACE PROJECT

Energy Technology Data Exchange (ETDEWEB)

Burton, Andrew J. [Michigan Technological University; Zak, Donald R. [University of Michigan; Kubiske, Mark E. [USDA Forest Service; Pregitzer, Kurt S. [University of Idaho

2014-06-30

Two of the most important and pervasive greenhouse gases driving global change and impacting forests in the U.S. and around the world are atmospheric CO2 and tropospheric O3. As the only free air, large-scale manipulative experiment studying the interaction of elevated CO2 and O3 on forests, the Aspen FACE experiment was uniquely designed to address the long-term ecosystem level impacts of these two greenhouse gases on aspen-birch-maple forests, which dominate the richly forested Lake States region. The project was established in 1997 to address the overarching scientific question: “What are the effects of elevated [CO2] and [O3], alone and in combination, on the structure and functioning of northern hardwood forest ecosystems?” From 1998 through the middle of the 2009 growing season, we examined the interacting effects of elevated CO2 and O3 on ecosystem processes in an aggrading northern forest ecosystem to compare the responses of early-successional, rapid-growing shade intolerant trembling aspen and paper birch to those of a late successional, slower growing shade tolerant sugar maple. Fumigations with elevated CO2 (560 ppm during daylight hours) and O3 (approximately 1.5 x ambient) were conducted during the growing season from 1998 to 2008, and in 2009 through harvest date. Response variables quantified during the experiment included growth, competitive interactions and stand dynamics, physiological processes, plant nutrient status and uptake, tissue biochemistry, litter quality and decomposition rates, hydrology, soil respiration, microbial community composition and respiration, VOC production, treatment-pest interactions, and treatment-phenology interactions. In 2009, we conducted a detailed harvest of the site. The harvest included detailed sampling of a subset of trees by component (leaves and buds, fine branches, coarse branches and stem, coarse roots, fine roots) and excavation of soil to a depth of 1 m. Throughout the experiment, aspen and birch

Interactive network configuration maintains bacterioplankton community structure under elevated CO2 in a eutrophic coastal mesocosm experiment

Science.gov (United States)

Lin, Xin; Huang, Ruiping; Li, Yan; Li, Futian; Wu, Yaping; Hutchins, David A.; Dai, Minhan; Gao, Kunshan

2018-01-01

There is increasing concern about the effects of ocean acidification on marine biogeochemical and ecological processes and the organisms that drive them, including marine bacteria. Here, we examine the effects of elevated CO2 on the bacterioplankton community during a mesocosm experiment using an artificial phytoplankton community in subtropical, eutrophic coastal waters of Xiamen, southern China. Through sequencing the bacterial 16S rRNA gene V3-V4 region, we found that the bacterioplankton community in this high-nutrient coastal environment was relatively resilient to changes in seawater carbonate chemistry. Based on comparative ecological network analysis, we found that elevated CO2 hardly altered the network structure of high-abundance bacterioplankton taxa but appeared to reassemble the community network of low abundance taxa. This led to relatively high resilience of the whole bacterioplankton community to the elevated CO2 level and associated chemical changes. We also observed that the Flavobacteria group, which plays an important role in the microbial carbon pump, showed higher relative abundance under the elevated CO2 condition during the early stage of the phytoplankton bloom in the mesocosms. Our results provide new insights into how elevated CO2 may influence bacterioplankton community structure.

Phytophthora quercina infections in elevated CO2 concentrations

Directory of Open Access Journals (Sweden)

Oszako Tomasz

2016-09-01

Full Text Available In the last decades, a new wave of oak decline has been observed in Poland. The most important pathogenic organisms involved in this phenomenon are probably soil-borne pathogens Phytophthoragenus, especially P. quercina. In this work, we sought to test the influence of elevated CO2 concentration on the susceptibility of oaks (Quercus robur L. to infection by P. quercina. In order to test the susceptibility of oak fine roots to infection, we applied phosphite-based fertiliser Actifos in 0.6% concentration. One-year-old oak seedlings were grown for one year in greenhouse with either an ambient atmosphere (400 ppm CO2 or an elevated (800 ppm concentration of CO2. Oaks grown at the elevated CO2 concentration developed longer shoots as proved by statistically significant differences. However, there was no difference in the development of root systems. The application of Actifos had a positive significant effect on the development of shoots and the surface area of fine roots under the elevated CO2 concentration.

Nitrogen Deifciency Limited the Improvement of Photosynthesis in Maize by Elevated CO2 Under Drought

Institute of Scientific and Technical Information of China (English)

ZONG Yu-zheng; SHANGGUAN Zhou-ping

2014-01-01

Global environmental change affects plant physiological and ecosystem processes. The interaction of elevated CO2, drought and nitrogen (N) deficiency result in complex responses of C4 species photosynthetic process that challenge our current understanding. An experiment of maize (Zea mays L.) involving CO2 concentrations (380 or 750 µmol mol-1, climate chamber), osmotic stresses (10% PEG-6000, -0.32 MPa) and nitrogen constraints (N deficiency treated since the 144th drought hour) was carried out to investigate its photosynthesis capacity and leaf nitrogen use efficiency. Elevated CO2 could alleviate drought-induced photosynthetic limitation through increasing capacity of PEPC carboxylation (Vpmax) and decreasing stomatal limitations (SL). The N deifciency exacerbated drought-induced photosynthesis limitations in ambient CO2. Elevated CO2 partially alleviated the limitation induced by drought and N deifciency through improving the capacity of Rubisco carboxylation (Vmax) and decreasing SL. Plants with N deifciency transported more N to their leaves at elevated CO2, leading to a high photosynthetic nitrogen-use efifciency but low whole-plant nitrogen-use efifciency. The stress mitigation by elevated CO2 under N deifciency conditions was not enough to improving plant N use efifciency and biomass accumulation. The study demonstrated that elevated CO2 could alleviate drought-induced photosynthesis limitation, but the alleviation varied with N supplies.

Antagonism between phytohormone signalling underlies the variation in disease susceptibility of tomato plants under elevated CO2

Science.gov (United States)

Zhang, Shuai; Li, Xin; Sun, Zenghui; Shao, Shujun; Hu, Lingfei; Ye, Meng; Zhou, Yanhong; Xia, Xiaojian; Yu, Jingquan; Shi, Kai

2015-01-01

Increasing CO2 concentrations ([CO2]) have the potential to disrupt plant–pathogen interactions in natural and agricultural ecosystems, but the research in this area has often produced conflicting results. Variations in phytohormone salicylic acid (SA) and jasmonic acid (JA) signalling could be associated with variations in the responses of pathogens to plants grown under elevated [CO2]. In this study, interactions between tomato plants and three pathogens with different infection strategies were compared. Elevated [CO2] generally favoured SA biosynthesis and signalling but repressed the JA pathway. The exposure of plants to elevated [CO2] revealed a lower incidence and severity of disease caused by tobacco mosaic virus (TMV) and by Pseudomonas syringae, whereas plant susceptibility to necrotrophic Botrytis cinerea increased. The elevated [CO2]-induced and basal resistance to TMV and P. syringae were completely abolished in plants in which the SA signalling pathway nonexpressor of pathogenesis-related genes 1 (NPR1) had been silenced or in transgenic plants defective in SA biosynthesis. In contrast, under both ambient and elevated [CO2], the susceptibility to B. cinerea highly increased in plants in which the JA signalling pathway proteinase inhibitors (PI) gene had been silenced or in a mutant affected in JA biosynthesis. However, plants affected in SA signalling remained less susceptible to this disease. These findings highlight the modulated antagonistic relationship between SA and JA that contributes to the variation in disease susceptibility under elevated [CO2]. This information will be critical for investigating how elevated CO2 may affect plant defence and the dynamics between plants and pathogens in both agricultural and natural ecosystems. PMID:25657213

Elevated CO2 and temperature increase soil C losses from a soybean-maize ecosystem.

Science.gov (United States)

Black, Christopher K; Davis, Sarah C; Hudiburg, Tara W; Bernacchi, Carl J; DeLucia, Evan H

2017-01-01

Warming temperatures and increasing CO 2 are likely to have large effects on the amount of carbon stored in soil, but predictions of these effects are poorly constrained. We elevated temperature (canopy: +2.8 °C; soil growing season: +1.8 °C; soil fallow: +2.3 °C) for 3 years within the 9th-11th years of an elevated CO 2 (+200 ppm) experiment on a maize-soybean agroecosystem, measured respiration by roots and soil microbes, and then used a process-based ecosystem model (DayCent) to simulate the decadal effects of warming and CO 2 enrichment on soil C. Both heating and elevated CO 2 increased respiration from soil microbes by ~20%, but heating reduced respiration from roots and rhizosphere by ~25%. The effects were additive, with no heat × CO 2 interactions. Particulate organic matter and total soil C declined over time in all treatments and were lower in elevated CO 2 plots than in ambient plots, but did not differ between heat treatments. We speculate that these declines indicate a priming effect, with increased C inputs under elevated CO 2 fueling a loss of old soil carbon. Model simulations of heated plots agreed with our observations and predicted loss of ~15% of soil organic C after 100 years of heating, but simulations of elevated CO 2 failed to predict the observed C losses and instead predicted a ~4% gain in soil organic C under any heating conditions. Despite model uncertainty, our empirical results suggest that combined, elevated CO 2 and temperature will lead to long-term declines in the amount of carbon stored in agricultural soils. © 2016 John Wiley & Sons Ltd.

Elevated CO{sub 2} levels and herbivore damage alter host plant preferences

Energy Technology Data Exchange (ETDEWEB)

Agrell, J. [Lund Univ., Dept. of Animal Ecology, Lund (Sweden); Anderson, Peter, Swedish Univ. of Agricultural Sciences, Dept. of Crop Sciences, Alnarp (SE)); Oleszek, W.; Stochmal, Anna [Inst. of Soil Science and Plant Cultivation, Dept. of Biochemistry, Pulawy (Poland); Agrell, Cecilia [Lund Univ., Dept. of Chemical Ecology and Ecotoxicology, Lund (Sweden)

2006-01-01

Interactions between the moth Spodoptera littoralis and two of its host plants, alfalfa (Medicago sativa) and cotton (Gossypium hirsutum) were examined, using plants grown under ambient (350 ppm) and elevated (700 ppm) CO{sub 2} conditions. To determine strength and effects of herbivore-induced responses assays were performed with both undamaged (control) and herbivore damaged plants. CO{sub 2} and damage effects on larval host plant preferences were determined through dual-choice bioassays. In addition, larvae were reared from hatching to pupation on experimental foliage to examine effects on larval growth and development. When undamaged plants were used S. littoralis larvae in consumed more cotton than alfalfa, and CO{sub 2} enrichment caused a reduction in the preference for cotton. With damaged plants larvae consumed equal amounts of the two plant species (ambient CO{sub 2} conditions), but CO{sub 2} enrichment strongly shifted preferences towards cotton, which was then consumed three times more than alfalfa. Complementary assays showed that elevated CO{sub 2} levels had no effect on the herbivore-induced responses of cotton, whereas those of alfalfa were significantly increased. Larval growth was highest for larvae fed undamaged cotton irrespectively of CO{sub 2} level, and lowest for larvae on damaged alfalfa from the high CO{sub 2} treatment. Development time increased on damaged cotton irrespectively of CO{sub 2} treatment, and on damaged alfalfa in the elevated CO{sub 2} treatment. (au) These results demonstrate that elevated CO2 levels can cause insect herbivores to alter host plant preferences, and that effects on herbivore-induced responses may be a key mechanism behind these processes. Furthermore, since the insects were shown to avoid foliage that reduced their physiological performance, our data suggest that behavioural host plant shifts result in partial escape from negative consequences of feeding on high CO2 foliage. Thus, CO2 enrichment can alter

Effects of decadal exposure to interacting elevated CO2 and/or O3 on paper birch (Betula papyrifera) reproduction.

Science.gov (United States)

Darbah, Joseph N T; Kubiske, Mark E; Nelson, Neil; Oksanen, Elina; Vapaavuori, Elina; Karnosky, David F

2008-10-01

We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO(2) and/or O(3) on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO(2) increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O(3) also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO(2)+O(3)) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO(2) may have a largely positive impact on forest tree reproduction and regeneration while elevated O(3) will likely have a negative impact.

Simulatd Nitrogen Cycling Response to Elevated CO2 in Pinus taeda and Mixed Dediduous Forests

Science.gov (United States)

D.W. Johnson

1999-01-01

Interactions between elevated CO2 and N cycling were explored with a nutrient cycling model (NuCM, Johnson et al. 1993, 1995) for a Pinus tuedu L. site at Duke University North Carolina, and a mixed deciduous site at Walker Branch, Tennessee. The simulations tested whether N limitation would prevent growth increases in response to elevated CO...

Impact of elevated CO2 and nitrogen fertilization on foliar elemental composition in a short rotation poplar plantation

International Nuclear Information System (INIS)

Marinari, Sara; Calfapietra, Carlo; De Angelis, Paolo; Mugnozza, Giuseppe Scarascia; Grego, Stefano

2007-01-01

The experiment was carried out on a short rotation coppice culture of poplars (POP-EUROFACE, Central Italy), growing in a free air carbon dioxide enriched atmosphere (FACE). The specific objective of this work was to study whether elevated CO 2 and fertilization (two CO 2 treatments, elevated CO 2 and control, two N fertilization treatments, fertilized and unfertilized), as well as the interaction between treatments caused an unbalanced nutritional status of leaves in three poplar species (P. x euramericana, P. nigra and P. alba). Finally, we discuss the ecological implications of a possible change in foliar nutrients concentration. CO 2 enrichment reduced foliar nitrogen and increased the concentration of magnesium; whereas nitrogen fertilization had opposite effects on leaf nitrogen and magnesium concentrations. Moreover, the interaction between elevated CO 2 and N fertilization amplified some element unbalances such as the K/N-ratio. - CO 2 enrichment reduced foliar nitrogen and increased the magnesium concentration in poplar

Elevated CO2 and O3 effects on fine-root survivorship in ponderosa pine mesocosms.

Science.gov (United States)

Phillips, Donald L; Johnson, Mark G; Tingey, David T; Storm, Marjorie J

2009-07-01

Atmospheric carbon dioxide (CO(2)) and ozone (O(3)) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO(2) and O(3) effects on roots, particularly fine-root life span, a critical demographic parameter and determinant of soil C and N pools and cycling rates. We conducted a study in which ponderosa pine (Pinus ponderosa) seedlings were exposed to two levels of CO(2) and O(3) in sun-lit controlled-environment mesocosms for 3 years. Minirhizotrons were used to monitor individual fine roots in three soil horizons every 28 days. Proportional hazards regression was used to analyze effects of CO(2), O(3), diameter, depth, and season of root initiation on fine-root survivorship. More fine roots were produced in the elevated CO(2) treatment than in ambient CO(2). Elevated CO(2), increasing root diameter, and increasing root depth all significantly increased fine-root survivorship and median life span. Life span was slightly, but not significantly, lower in elevated O(3), and increased O(3) did not reduce the effect of elevated CO(2). Median life spans varied from 140 to 448 days depending on the season of root initiation. These results indicate the potential for elevated CO(2) to increase the number of fine roots and their residence time in the soil, which is also affected by root diameter, root depth, and phenology.

Nitrogen fertilization has a stronger effect on soil nitrogen-fixing bacterial communities than elevated atmospheric CO2.

Science.gov (United States)

Berthrong, Sean T; Yeager, Chris M; Gallegos-Graves, Laverne; Steven, Blaire; Eichorst, Stephanie A; Jackson, Robert B; Kuske, Cheryl R

2014-05-01

Biological nitrogen fixation is the primary supply of N to most ecosystems, yet there is considerable uncertainty about how N-fixing bacteria will respond to global change factors such as increasing atmospheric CO2 and N deposition. Using the nifH gene as a molecular marker, we studied how the community structure of N-fixing soil bacteria from temperate pine, aspen, and sweet gum stands and a brackish tidal marsh responded to multiyear elevated CO2 conditions. We also examined how N availability, specifically, N fertilization, interacted with elevated CO2 to affect these communities in the temperate pine forest. Based on data from Sanger sequencing and quantitative PCR, the soil nifH composition in the three forest systems was dominated by species in the Geobacteraceae and, to a lesser extent, Alphaproteobacteria. The N-fixing-bacterial-community structure was subtly altered after 10 or more years of elevated atmospheric CO2, and the observed shifts differed in each biome. In the pine forest, N fertilization had a stronger effect on nifH community structure than elevated CO2 and suppressed the diversity and abundance of N-fixing bacteria under elevated atmospheric CO2 conditions. These results indicate that N-fixing bacteria have complex, interacting responses that will be important for understanding ecosystem productivity in a changing climate.

Regulation of senescence under elevated atmospheric CO2 via ubiquitin modification

OpenAIRE

Aoyama, Shoki; Lu, Yu; Yamaguchi, Junji; Sato, Takeo

2014-01-01

Elevated atmospheric CO2 concentration is a serious global environmental problem. Elevated CO2 affects plant growth by changing primary metabolism, closely related to carbon (C) and nitrogen (N) availability. Under sufficient N conditions, plant growth is dramatically promoted by elevated CO2. When N availability is limited, however, elevated CO2 disrupts the balance between cellular C and N (C/N). Disruption of the C/N balance is regarded as an important factor in plant growth defects. Here ...

Physiological responses of Norway spruce trees to elevated CO2 and SO2

NARCIS (Netherlands)

Tausz, M.; De Kok, L.J.; Stulen, I.

Young Norway spruce (Picea abies (L.) Karst.) trees were exposed to elevated CO2 (0.8 mL L(-1)), SO2 (0.06 mu L L(-1)), and elevated CO2 and SO2 (0.8 mL L(-1) and 0.06 mu L L(-1), respectively) for three months. Exposure to elevated CO2 resulted in an increased biomass production of the needles,

Elevated tropospheric CO2 and O3 concentrations impair organic pollutant removal from grassland soil.

Science.gov (United States)

Ai, Fuxun; Eisenhauer, Nico; Jousset, Alexandre; Butenschoen, Olaf; Ji, Rong; Guo, Hongyan

2018-04-03

The concentrations of tropospheric CO 2 and O 3 have been rising due to human activities. These rising concentrations may have strong impacts on soil functions as changes in plant physiology may lead to altered plant-soil interactions. Here, the effects of eCO 2 and eO 3 on the removal of polycyclic aromatic hydrocarbon (PAH) pollutants in grassland soil were studied. Both elevated CO 2 and O 3 concentrations decreased PAH removal with lowest removal rates at elevated CO 2 and elevated O 3 concentrations. This effect was linked to a shift in soil microbial community structure by structural equation modeling. Elevated CO 2 and O 3 concentrations reduced the abundance of gram-positive bacteria, which were tightly linked to soil enzyme production and PAH degradation. Although plant diversity did not buffer CO 2 and O 3 effects, certain soil microbial communities and functions were affected by plant communities, indicating the potential for longer-term phytoremediation approaches. Results of this study show that elevated CO 2 and O 3 concentrations may compromise the ability of soils to degrade organic pollutants. On the other hand, the present study also indicates that the targeted assembly of plant communities may be a promising tool to shape soil microbial communities for the degradation of organic pollutants in a changing world.

The interactive effects of elevated CO2, temperature and N supply on rice yield

International Nuclear Information System (INIS)

Baysa, Marieta C.; Tremmel, David C.; Reynolds, James F.; Rivero, Gilda C.; Tabbada, Reynaldo A.

2001-01-01

Rice (Oryza sativa L. cv. IR 72)was grown in growth chambers under combinations of two CO 2 (375 and 750 μL L -1 ), temperature(29/21 and 34/26 degrees centigrade day/night) and N (40 and 80 mg L -1 ) regimes from sowing until grain maturity. Panicle production was significantly enhanced by elevated CO 2 with more pronounced effects at high temperature and N. CO 2 -enriched plants grown at high temperatures had lower harvest indices due to reductions in the number of grains per panicle and grain mass. Any potential benefit of increased atmospheric CO 2 on rice grain yield and grain N content under optimal N supply may therefore be dampened by higher temperatures associated with possible future global warming conditions. (Author)

Is guava phenolic metabolism influenced by elevated atmospheric CO2?

Science.gov (United States)

Mendes de Rezende, Fernanda; Pereira de Souza, Amanda; Silveira Buckeridge, Marcos; Maria Furlan, Cláudia

2015-01-01

Seedlings of Psidium guajava cv. Pedro Sato were distributed into four open-top chambers: two with ambient CO(2) (∼390 ppm) and two with elevated CO(2) (∼780 ppm). Monthly, five individuals of each chamber were collected, separated into root, stem and leaves and immediately frozen in liquid nitrogen. Chemical parameters were analyzed to investigate how guava invests the surplus carbon. For all classes of phenolic compounds analyzed only tannins showed significant increase in plants at elevated CO(2) after 90 days. There was no significant difference in dry biomass, but the leaves showed high accumulation of starch under elevated CO(2). Results suggest that elevated CO(2) seems to be favorable to seedlings of P. guajava, due to accumulation of starch and tannins, the latter being an important anti-herbivore substance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of elevated CO2, warming and drought episodes on plant carbon uptake in a temperate heath ecosystem are controlled by soil water status

DEFF Research Database (Denmark)

Albert, Kristian Rost; Ro-Poulsen, H.; Mikkelsen, Teis Nørgaard

2011-01-01

The impact of elevated CO2, periodic drought and warming on photosynthesis and leaf characteristics of the evergreen dwarf shrub Calluna vulgaris in a temperate heath ecosystem was investigated. Photosynthesis was reduced by drought in midsummer and increased by elevated CO2 throughout the growing...... season, whereas warming only stimulated photosynthesis early in the year. At the beginning and end of the growing season, a T × CO2 interaction synergistically stimulated plant carbon uptake in the combination of warming and elevated CO2. At peak drought, the D × CO2 interaction antagonistically down......-regulated photosynthesis, suggesting a limited ability of elevated CO2 to counteract the negative effect of drought. The response of photosynthesis in the full factorial combination (TDCO2) could be explained by the main effect of experimental treatments (T, D, CO2) and the two-factor interactions (D × CO2, T × CO2...

Early growth interactions between a mangrove and an herbaceous salt marsh species are not affected by elevated CO2 or drought

Science.gov (United States)

Howard, Rebecca J.; Stagg, Camille L.; Utomo, Herry S.

2018-01-01

Increasing atmospheric carbon dioxide (CO2) concentrations are likely to influence future distributions of plants and plant community structure in many regions of the world through effects on photosynthetic rates. In recent decades the encroachment of woody mangrove species into herbaceous marshes has been documented along the U.S. northern Gulf of Mexico coast. These species shifts have been attributed primarily to rising sea levels and warming winter temperatures, but the role of elevated CO2 and water availability may become more prominent drivers of species interactions under future climate conditions. Drought has been implicated as a major factor contributing to salt marsh vegetation dieback in this region. In this greenhouse study we examined the effects of CO2 concentration (∼380 ppm, ∼700 ppm) and water regime (drought, saturated, flooded) on early growth of Avicennia germinans, a C3 mangrove species, and Spartina alterniflora, a C4 grass. Plants were grown in monocultures and in a mixed-species assemblage. We found that neither species responded to elevated CO2 over the 10-month duration of the experiment, and there were few interactions between experimental factors. Two effects of water regime were documented: lower A. germinanspneumatophore biomass under drought conditions, and lower belowground biomass under flooded conditions regardless of planting assemblage. Evidence of interspecific interactions was noted. Competition for aboveground resources (e.g., light) was indicated by lower S. alterniflora stem biomass in mixed-species assemblage compared to biomass in S. alterniflora monocultures. Pneumatophore biomass of A. germinans was reduced when grown in monoculture compared to the mixed-species assemblage, indicating competition for belowground resources. These interactions provide insight into how these species may respond following major disturbance events that lead to vegetation dieback. Site variation in propagule availability

Response of Tundra Ecosystems to Elevated Atmospheric CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Oechel, Walter C.

1990-09-05

OAK B188 Response of Tundra Ecosystems to Elevated Atmospheric CO{sub 2}. Atmospheric CO{sub 2} is expected to double by the end of the next century. Global mean increases in surface air temperature of 1.5-4.5 C are anticipated with larger increases towards the poles predicted. Changes in CO{sub 2} levels and temperature could have major impacts on ecosystem functioning, including primary productivity, species composition, plant-animal interactions, and carbon storage. Until recently, there has been little direct information on the impact of changes in CO{sub 2} and temperature on native ecosystems. The study described here was undertaken to evaluate the effects of a 50 and 100% increase in atmospheric CO{sub 2}, and a 100% increase in atmospheric CO{sub 2} coupled with a 4 C summer air temperature rise on the structure and function of an arctic tussock tundra ecosystem. The arctic contains large stores of carbon as soil organic matter, much frozen in permafrost and currently not reactive or available for oxidation and release into the atmosphere. About 10-27% of the world's terrestrial carbon occurs in arctic and boreal regions, and carbon is accumulating in these regions at the rate of 0.19 GT y{sup -1}. Mean temperature increases of 11 C and summer temperature increases of 4 C have been suggested. Mean July temperatures on the arctic coastal plain and arctic foothills regions are 4-12 C, and mean annual temperatures are -7 to -13 C (Haugen, 1982). The projected temperature increases represent a substantial elevation above current temperatures which will have major impacts on physical processes such as permafrost development and development of the active layer, and on biological and ecosystem processes such as primary productivity, carbon storage, and species composition. Extreme nutrient and temperature limitation of this ecosystem raised questions of the responsiveness of arctic systems to elevated CO{sub 2}. Complex ecosystem interactions with the effects

Does Elevated CO2 Alter Silica Uptake in Trees?

Directory of Open Access Journals (Sweden)

Robinson W. Fulweiler

2015-01-01

Full Text Available Human activities have greatly altered global carbon (C and N (N cycling. In fact, atmospheric concentrations of carbon dioxide (CO2 have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global carbon dioxide fertilization, long-term free-air CO2 enrichment (FACE experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine, and five hardwood species. Specifically, we measured foliar biogenic silica (BSi concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20% and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.

Plant growth responses to elevated atmospheric CO2 are increased by phosphorus sufficiency but not by arbuscular mycorrhizas

DEFF Research Database (Denmark)

Jakobsen, Iver; Smith, Sally E.; Smith, F. Andrew

2016-01-01

Capturing the full growth potential in crops under future elevated CO2 (eCO2) concentrations would be facilitated by improved understanding of eCO2 effects on uptake and use of mineral nutrients. This study investigates interactions of eCO2, soil phosphorus (P), and arbuscular mycorrhizal (AM......) symbiosis in Medicago truncatula and Brachypodium distachyon grown under the same conditions. The focus was on eCO2 effects on vegetative growth, efficiency in acquisition and use of P, and expression of phosphate transporter (PT) genes. Growth responses to eCO2 were positive at P sufficiency, but under low......-P conditions they ranged from non-significant in M. truncatula to highly significant in B. distachyon. Growth of M. truncatula was increased by AM at low P conditions at both CO2 levels and eCO2×AM interactions were sparse. Elevated CO2 had small effects on P acquisition, but enhanced conversion of tissue P...

Plant–plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2: an experiment with plant populations from naturally high CO2 areas

Science.gov (United States)

van Loon, Marloes P.; Rietkerk, Max; Dekker, Stefan C.; Hikosaka, Kouki; Ueda, Miki U.; Anten, Niels P. R.

2016-01-01

Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant–plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may benefit more from [CO2] elevation than others. The relative contribution of plastic (within the plant’s lifetime) and genotypic (over several generations) responses to elevated [CO2] on plant performance was investigated and how these patterns are modified by plant–plant interactions was analysed. Methods Plantago asiatica seeds originating from natural CO2 springs and from ambient [CO2] sites were grown in mono stands of each one of the two origins as well as mixtures of both origins. In total, 1944 plants were grown in [CO2]-controlled walk-in climate rooms, under a [CO2] of 270, 450 and 750 ppm. A model was used for upscaling from leaf to whole-plant photosynthesis and for quantifying the influence of plastic and genotypic responses. Key Results It was shown that changes in canopy photosynthesis, specific leaf area (SLA) and stomatal conductance in response to changes in growth [CO2] were mainly determined by plastic and not by genotypic responses. We further found that plants originating from high [CO2] habitats performed better in terms of whole-plant photosynthesis, biomass and leaf area, than those from ambient [CO2] habitats at elevated [CO2] only when both genotypes competed. Similarly, plants from ambient [CO2] habitats performed better at low [CO2], also only when both genotypes competed. No difference in performance was found in mono stands. Conclusion The results indicate that natural selection under increasing [CO2] will be mainly driven by competitive interactions. This supports the notion that plant–plant interactions have an important influence on future vegetation functioning and species distribution. Furthermore, plant performance was mainly

Elevated CO2 changes interspecific competition among three species of wheat aphids: Sitobion avenae, Rhopalosiphum padi, and Schizaphis graminum.

Science.gov (United States)

Sun, Yu Cheng; Chen, Fa Jun; Ge, Feng

2009-02-01

Effects of elevated CO2 (twice ambient) on the interspecific competition among three species of wheat aphids (Sitobion avenae, Rhopalosiphum padi, and Schizaphis graminum) and on wheat-aphid interactions were studied. Wheat plants had higher biomass and yield and lower water and nitrogen content of grain when grown under elevated CO2 than under ambient CO2; levels of condensed tannins, total phenols, and total nonstructural carbohydrates were also higher in wheat ears under elevated CO2. Compared with ambient CO2, elevated CO2 increased the abundance of R. padi when introduced solely but reduced its abundance when S. avenae was also present. The spatial distribution of wheat aphids was apparently influenced by CO2 levels, with significantly more S. avenae on ears and a more even distribution of R. padi on wheat plants under elevated CO2 versus ambient CO2. Elevated CO2 did not affect the abundance and spatial distribution of S. graminus when inoculated solely. Moreover, when S. avenae was present with either R. padi or S. graminum, spatial niche overlap was significantly decreased with elevated CO2. When three species co-occurred, elevated CO2 reduced spatial niche overlap between S. avenae and S. graminum and between R. padi and S. graminum. Our results suggest that increases in atmospheric CO2 would alleviate interspecific competition for these cases, which would accentuate the abundance of and the damage caused by these wheat aphids.

Elevated CO2 promotes long-term nitrogen accumulation only in combination with nitrogen addition.

Science.gov (United States)

Pastore, Melissa A; Megonigal, J Patrick; Langley, J Adam

2016-01-01

Biogeochemical models that incorporate nitrogen (N) limitation indicate that N availability will control the magnitude of ecosystem carbon uptake in response to rising CO2 . Some models, however, suggest that elevated CO2 may promote ecosystem N accumulation, a feedback that in the long term could circumvent N limitation of the CO2 response while mitigating N pollution. We tested this prediction using a nine-year CO2 xN experiment in a tidal marsh. Although the effects of CO2 are similar between uplands and wetlands in many respects, this experiment offers a greater likelihood of detecting CO2 effects on N retention on a decadal timescale because tidal marshes have a relatively open N cycle and can accrue soil organic matter rapidly. To determine how elevated CO2 affects N dynamics, we assessed the three primary fates of N in a tidal marsh: (1) retention in plants and soil, (2) denitrification to the atmosphere, and (3) tidal export. We assessed changes in N pools and tracked the fate of a (15) N tracer added to each plot in 2006 to quantify the fraction of added N retained in vegetation and soil, and to estimate lateral N movement. Elevated CO2 alone did not increase plant N mass, soil N mass, or (15) N label retention. Unexpectedly, CO2 and N interacted such that the combined N+CO2 treatment increased ecosystem N accumulation despite the stimulation in N losses indicated by reduced (15) N label retention. These findings suggest that in N-limited ecosystems, elevated CO2 is unlikely to increase long-term N accumulation and circumvent progressive N limitation without additional N inputs, which may relieve plant-microbe competition and allow for increased plant N uptake. © 2015 John Wiley & Sons Ltd.

Low vapour pressure deficit reduces the beneficial effect of elevated CO{sub 2} on growth of N{sub 2}-fixing alfalfa plants

Energy Technology Data Exchange (ETDEWEB)

Luis, I. De; Irigoyen, J.J.; Sanchez-Diaz, M. [Univ. de Navarra, Dept. de Fisioligia Vegetal, Pamplona (Spain)

2002-11-01

Plant responses to elevated CO{sub 2} can be modified by many environmental factors, but very little attention has been paid to the interaction between CO{sub 2} and changes in vapour pressure deficit (VPD). Thirty-day-old alfalfa plants (Medicago sativa L. cv. Aragon), which were inoculated with Sinorhizobium meliloti 102F78 strain, were grown for 1 month in controlled environment chambers at 25/15 deg C, 14 h photoperiod, and 600 mol m{sup -2} s{sup -1} photosynthetic photon flux (PPF), using a factorial combination of CO{sub 2} concentration (400 mol mol{sup -1} or 700 mol mol{sup -1}) and vapour pressure deficit (0.48 kPa or 1.74 kPa, which corresponded to relative humidities of 85% and 45% at 25 deg C, respectively). Elevated CO{sub 2} strongly stimulated plant growth under high VPD conditions, but this beneficial effect was not observed under low VPD. Under low VPD, elevated CO{sub 2} also did not enhance plant photosynthesis, and plant water stress was greatest for plants grown at elevated CO{sub 2} and low VPD. Moreover, plants grown under elevated CO{sub 2} and low VPD had a lower leaf soluble protein and photosynthetic activity (photosynthetic rate and carboxylation efficiency) than plants grown under elevated CO{sub 2} and high VPD. Elevated CO{sub 2} significantly increased leaf adaxial and abaxial temperatures. Because the effects of elevated CO{sub 2} were dependent on vapour pressure deficit, VPD needs to be controlled in experiments studying the effect of elevated CO{sub 2} as well as considered in the extrapolations of results to a warmer, high-CO{sub 2} world. (au)

Interactive effect of temperature and CO2 increase in Arctic phytoplankton

Directory of Open Access Journals (Sweden)

Alexandra eCoello-Camba

2014-10-01

Full Text Available An experiment was performed in order to analyze the effects of the increase in water temperature and CO2 partial pressure expected for the end of this century in a present phytoplankton community inhabiting the Arctic Ocean. We analyzed both factors acting independently and together, to test possible interactions between them. The arctic planktonic community was incubated under 6 different treatments combining three experimental temperatures (1 ºC, 6 ºC and 10 ºC with two different CO2 levels of 380 ppm or 1000 ppm, at the UNIS installations in Longyearbyen (Svalbard, in summer 2010. Under warmer temperatures, a decrease in chlorophyll a concentration, biovolume and primary production was found, together with a shift in community structure towards a dominance of smaller cells (nano-sized. Effects of increased pCO2 were more modest, and although interactions were weak, our results suggest antagonistic interactive effects amongst increased temperature and CO2 levels, as elevated CO2 compensated partially the decrease in phytoplankton biomass induced by temperature in some groups. Interactions between the two stressors were generally weak, but elevated CO2 was observed to lead to a stepper decline in primary production with warming. Our results also suggest that future increases in water temperature and pCO2 would lead to a decrease in the community chl a concentration and biomass in the Arctic phytoplankton communities examined, leading to communities dominated by smaller nano-phytoplankton groups, with important consequences for the flow of carbon and food web dynamics.

INTERACTIVE EFFECTS OF ELEVATED CO2 AND 03 ON RICE AND FLACCA TOMATO

Science.gov (United States)

All atmospheric concentrations of both carbon dioxide (CO2) and ozone (03) are increasing, with potentially dramatic effects on plants. This study was conducted to determine interactive effects of CO2 and 03 on rice (Oryza sativa L. cv. IR 74) and a 'wilty' mutant of tomato (Lyco...

Above- and below-ground responses of Calamagrostis purpurea to UV-B radiation and elevated CO{sub 2} under phosphorus limitation

Energy Technology Data Exchange (ETDEWEB)

Bussell, J.S.; Gwynn-Jones, D.; Griffith, G.W.; Scullion, J. (Aberystwyth Univ., IBERS, Wales (United Kingdom))

2012-08-15

UV-B radiation and elevated CO{sub 2} may impact rhizosphere processes through altered below-ground plant resource allocation and root exudation, changes that may have implications for nutrient acquisition. As nutrients limit plant growth in many habitats, their supply may dictate plant response under elevated CO{sub 2}. This study investigated UV-B exposure and elevated CO{sub 2} effects, including interactions, on plant growth, tissue chemistry and rooting responses relating to P acquisition. The sub-arctic grass Calamagrostis purpurea was subjected to UV-B (0 or 3.04 kJ m-2day-1) and CO{sub 2} (ambient 380 or 650 ppmv) treatments in a factorial glasshouse experiment, with sparingly soluble P (0 or 0.152 mg P per plant as FePO{sub 4}) a further factor. It was hypothesized that UV-B exposure and elevated CO{sub 2} would change plant resource allocation, with CO{sub 2} mitigating adverse responses to UV-B exposure and aiding P uptake. Plant biomass and morphology, tissue composition and rhizosphere leachate properties were measured. UV-B directly affected chemical composition of shoots and interacted with CO{sub 2} to give a greater root biomass. Elevated CO{sub 2} altered the composition of both shoots and roots and increased shoot biomass and secondary root length, while leachate pH decreased. Below-ground responses to CO{sub 2} did not affect P acquisition although P limitation progressively reduced leachate pH and increased secondary root length. Although direct plant growth, foliar composition and below-ground nutrient acquisition responses were dominated by CO{sub 2} treatments, UV-B modified these CO{sub 2} responses significantly. These interactions have implications for plant responses to future atmospheric conditions. (Author)

Impact of elevated CO2 and elevated O3 on Beta vulgaris L.: Pigments, metabolites, antioxidants, growth and yield

International Nuclear Information System (INIS)

Kumari, Sumita; Agrawal, Madhoolika; Tiwari, Supriya

2013-01-01

The present study was conducted to assess morphological, biochemical and yield responses of palak (Beta vulgaris L. cv Allgreen) to ambient and elevated levels of CO 2 and O 3 , alone and in combination. As compared to the plants grown in charcoal filtered air (ACO 2 ), growth and yield of the plants increased under elevated CO 2 (ECO 2 ) and decreased under combination of ECO 2 with elevated O 3 (ECO 2 + EO 3 ), ambient O 3 (ACO 2 + AO 3 ) and elevated O 3 (EO 3 ). Lipid peroxidation, ascorbic acid, catalase and glutathione reductase activities enhanced under all treatments and were highest in EO 3. Foliar starch and organic carbon contents increased under ECO 2 and ECO 2 + EO 3 and reduced under EO 3 and ACO 2 + AO 3. Foliar N content declined in all treatments compared to ACO 2 resulting in alteration of C/N ratio. This study concludes that ambient level of CO 2 is not enough to counteract O 3 impact, but elevated CO 2 has potential to counteract the negative effects of future O 3 level. -- Highlights: ► Elevated CO 2 enhanced the growth and yield of palak. ► Ambient and elevated ozone reduced the growth and yield of the test plant. ► Elevated CO 2 reduced negative effects of elevated O 3 by reducing oxidative stress. ► Higher amelioration was recorded at elevated CO 2 + O 3 compared to ambient CO 2 + O 3 . -- Predicted levels of CO 2 have greater ameliorative potential against negative effects of elevated ozone compared to present day CO 2 against ambient ozone

Interactive Effects of Elevated CO2 and N Fertilization on Yield and Quality of Tomato Grown Under Reduced Irrigation Regimes

Directory of Open Access Journals (Sweden)

Zhenhua Wei

2018-03-01

Full Text Available The interactive effects of CO2 elevation, N fertilization, and reduced irrigation regimes on fruit yield (FY and quality in tomato (Solanum lycopersicum L. were investigated in a split-root pot experiment. The plants were grown in two separate climate-controlled greenhouse cells at atmospheric [CO2] of 400 and 800 ppm, respectively. In each cell, the plants were fertilized at either 100 or 200 mg N kg-1 soil and were either irrigated to full water holding capacity [i.e., a volumetric soil water content of 18%; full irrigation (FI], or using 70% water of FI to the whole pot [deficit irrigation (DI] or alternately to only half of the pot [partial root-zone irrigation (PRI]. The yield and fruit quality attributes mainly from sugars (sucrose, fructose, and glucose and organic acids (OAs; citric acid and malic acid to various ionic (NH4+, K+, Mg2+, Ca2+, NO3-, SO42-, and PO43- concentrations in fruit juice were determined. The results indicated that lower N supply reduced fruit number and yield, whereas it enhanced some of the quality attributes of fruit as indicated by greater firmness and higher concentrations of sugars and OAs. Elevated [CO2] (e[CO2] attenuated the negative influence of reduced irrigation (DI and PRI on FY. Principal component analysis revealed that the reduced irrigation regimes, especially PRI, in combination with e[CO2] could synergistically improve the comprehensive quality of tomato fruits at high N supply. These findings provide useful knowledge for sustaining tomato FY and quality in a future drier and CO2-enriched environment.

Photosynthesis and metabolite responses of Isatis indigotica Fortune to elevated [CO2

Institute of Scientific and Technical Information of China (English)

Ping Li; Hongying Li; Yuzheng Zong; Frank Yonghong Li; Yuanhuai Han; Xingyu Hao

2017-01-01

Climate change is affecting global crop productivity, food quality, and security. However, few studies have addressed the mechanism by which elevated CO2 may affect the growth of medicinal plants. Isatis indigotica Fortune is a widely used Chinese medicinal herb with multiple pharmacological properties. To investigate the physiological mechanism of I. indigotica response to elevated [CO2], plants were grown at either ambient [CO2] (385μmol mol?1) or elevated [CO2] (590μmol mol?1) in an open-top chamber (OTC) experimental facility in North China. A significant reduction in transpiration rate (Tr) and stomatal conductance (gs) and a large increase in water-use efficiency contributed to an increase in net photosynthetic rate (Pn) under elevated [CO2] 76 days after sowing. Leaf non-photochemical quenching (NPQ) was decreased, so that more energy was used in effective quantum yield of PSII photochemistry (ΦPSI ) under elevated [CO2]. High ΦPSI , meaning high electron transfer efficiency, also increased Pn. The [CO2]-induced increase in photosynthesis significantly increased biomass by 36.8%. Amounts of metabolic compounds involved in sucrose metabolism, pyrimidine metabolism, flavonoid biosynthesis, and other processes in leaves were reduced under elevated [CO2]. These results showed that the fertilization effect of elevated [CO2] is conducive to increasing dry weight but not secondary metabolism in I. indigotica.

Genotype influences sulfur metabolism in broccoli (Brassica oleracea L.) under elevated CO2 and NaCl stress.

Science.gov (United States)

Rodríguez-Hernández, María del Carmen; Moreno, Diego A; Carvajal, Micaela; Martínez-Ballesta, María del Carmen

2014-12-01

Climatic change predicts elevated salinity in soils as well as increased carbon dioxide dioxide [CO2] in the atmosphere. The present study aims to determine the effect of combined salinity and elevated [CO2] on sulfur (S) metabolism and S-derived phytochemicals in green and purple broccoli (cv. Naxos and cv. Viola, respectively). Elevated [CO2] involved the amelioration of salt stress, especially in cv. Viola, where a lower biomass reduction by salinity was accompanied by higher sodium (Na(+)) and chloride (Cl(-)) compartmentation in the vacuole. Moreover, salinity and elevated [CO2] affected the mineral and glucosinolate contents and the activity of biosynthetic enzymes of S-derived compounds and the degradative enzyme of glucosinolate metabolism, myrosinase, as well as the related amino acids and the antioxidant glutathione (GSH). In cv. Naxos, elevated [CO2] may trigger the antioxidant response to saline stress by means of increased GSH concentration. Also, in cv. Naxos, indolic glucosinolates were more influenced by the NaCl×CO2 interaction whereas in cv. Viola the aliphatic glucosinolates were significantly increased by these conditions. Salinity and elevated [CO2] enhanced the S cellular partitioning and metabolism affecting the myrosinase-glucosinolate system. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Plants increase laccase activity in soil with long-term elevated CO2 legacy

DEFF Research Database (Denmark)

Partavian, Asrin; Mikkelsen, Teis Nørgaard; Vestergård, Mette

2015-01-01

[CO2] stimulate laccase activity. We incubated soil exposed to seven years of elevated or ambient field [CO2] in ambient or elevated [CO2] chambers for six months either with or without plants (Deschampsia flexuosa). Elevated chamber [CO2] increased D. flexuosa production and belowground respiration....... Interestingly, plants also grew larger in soil with an elevated [CO2] legacy. Plants stimulated soil microbial biomass, belowground respiration and laccase activity, and the plant-induced laccase stimulation was particularly apparent in soil exposed to long-term elevated [CO2] in the field, whereas laccase......Actively growing plants can stimulate mineralization of recalcitrant soil organic matter (SOM), and increased atmospheric [CO2] can further enhance such plant-mediated SOM degradation. Laccases are central for recalcitrant SOM decomposition, and we therefore hypothesized that plants and elevated...

Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2: an experiment with plant populations from naturally high CO2 areas.

Science.gov (United States)

van Loon, Marloes P; Rietkerk, Max; Dekker, Stefan C; Hikosaka, Kouki; Ueda, Miki U; Anten, Niels P R

2016-06-01

The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant-plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may benefit more from [CO2] elevation than others. The relative contribution of plastic (within the plant's lifetime) and genotypic (over several generations) responses to elevated [CO2] on plant performance was investigated and how these patterns are modified by plant-plant interactions was analysed. Plantago asiatica seeds originating from natural CO2 springs and from ambient [CO2] sites were grown in mono stands of each one of the two origins as well as mixtures of both origins. In total, 1944 plants were grown in [CO2]-controlled walk-in climate rooms, under a [CO2] of 270, 450 and 750 ppm. A model was used for upscaling from leaf to whole-plant photosynthesis and for quantifying the influence of plastic and genotypic responses. It was shown that changes in canopy photosynthesis, specific leaf area (SLA) and stomatal conductance in response to changes in growth [CO2] were mainly determined by plastic and not by genotypic responses. We further found that plants originating from high [CO2] habitats performed better in terms of whole-plant photosynthesis, biomass and leaf area, than those from ambient [CO2] habitats at elevated [CO2] only when both genotypes competed. Similarly, plants from ambient [CO2] habitats performed better at low [CO2], also only when both genotypes competed. No difference in performance was found in mono stands. The results indicate that natural selection under increasing [CO2] will be mainly driven by competitive interactions. This supports the notion that plant-plant interactions have an important influence on future vegetation functioning and species distribution. Furthermore, plant performance was mainly driven by plastic and not by genotypic responses to changes in

Quantifying Direct and Indirect Effects of Elevated CO2 on Ecosystem Response

Science.gov (United States)

Fatichi, S.; Leuzinger, S.; Paschalis, A.; Donnellan-Barraclough, A.; Hovenden, M. J.; Langley, J. A.

2015-12-01

Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation, evapotranspiration (ET) and ultimately plant growth. Direct leaf biochemical effects have been widely investigated, while indirect effects, although documented, are very difficult to quantify in experiments. We hypothesize that the interaction of direct and indirect effects is a possible reason for conflicting results concerning the magnitude of CO2 fertilization effects across different climates and ecosystems. A mechanistic ecohydrological model (Tethys-Chloris) is used to investigate the relative contribution of direct (through plant physiology) and indirect (via stomatal closure and thus soil moisture, and changes in Leaf Area Index, LAI) effects of elevated CO2 across a number of ecosystems. We specifically ask in which ecosystems and climate indirect effects are expected to be largest. Data and boundary conditions from flux-towers and free air CO2 enrichment (FACE) experiments are used to force the model and evaluate its performance. Numerical results suggest that indirect effects of elevated CO2, through water savings and increased LAI, are very significant and sometimes larger than direct effects. Indirect effects tend to be considerably larger in water-limited ecosystems, while direct effects correlate positively with mean air temperature. Increasing CO2 from 375 to 550 ppm causes a total effect on Net Primary Production in the order of 15 to 40% and on ET from 0 to -8%, depending on climate and ecosystem type. The total CO2 effect has a significant negative correlation with the wetness index and positive correlation with vapor pressure deficit. These results provide a more general mechanistic understanding of relatively short-term (less than 20 years) implications of elevated CO2 on ecosystem response and suggest plausible magnitudes for the expected changes.

Elevated CO2 did not mitigate the effect of a short-term drought on biological soil crusts

Science.gov (United States)

Wertin, Timothy M.; Phillips, Susan L.; Reed, Sasha C.; Belnap, Jayne

2012-01-01

Biological soil crusts (biocrusts) are critical components of arid and semi-arid ecosystems that contribute significantly to carbon (C) and nitrogen (N) fixation, water retention, soil stability, and seedling recruitment. While dry-land ecosystems face a number of environmental changes, our understanding of how biocrusts may respond to such perturbation remains notably poor. To determine the effect that elevated CO2 may have on biocrust composition, cover, and function, we measured percent soil surface cover, effective quantum yield, and pigment concentrations of naturally occurring biocrusts growing in ambient and elevated CO2 at the desert study site in Nevada, USA, from spring 2005 through spring 2007. During the experiment, a year-long drought allowed us to explore the interacting effects that elevated CO2 and water availability may have on biocrust cover and function. We found that, regardless of CO2 treatment, precipitation was the major regulator of biocrust cover. Drought reduced moss and lichen cover to near-zero in both ambient and elevated CO2 plots, suggesting that elevated CO2 did not alleviate water stress or increase C fixation to levels sufficient to mitigate drought-induced reduction in cover. In line with this result, lichen quantum yield and soil cyanobacteria pigment concentrations appeared more strongly dependent upon recent precipitation than CO2 treatment, although we did find evidence that, when hydrated, elevated CO2 increased lichen C fixation potential. Thus, an increase in atmospheric CO2 may only benefit biocrusts if overall climate patterns shift to create a wetter soil environment.

Does a decade of elevated [CO2] affect a desert perennial plant community?

Science.gov (United States)

Newingham, Beth A; Vanier, Cheryl H; Kelly, Lauren J; Charlet, Therese N; Smith, Stanley D

2014-01-01

Understanding the effects of elevated [CO2 ] on plant community structure is crucial to predicting ecosystem responses to global change. Early predictions suggested that productivity in deserts would increase via enhanced water-use efficiency under elevated [CO2], but the response of intact arid plant communities to elevated [CO2 ] is largely unknown. We measured changes in perennial plant community characteristics (cover, species richness and diversity) after 10 yr of elevated [CO2] exposure in an intact Mojave Desert community at the Nevada Desert Free-Air CO2 Enrichment (FACE) Facility. Contrary to expectations, total cover, species richness, and diversity were not affected by elevated [CO2]. Over the course of the experiment, elevated [CO2] had no effect on changes in cover of the evergreen C3 shrub, Larrea tridentata; alleviated decreases in cover of the C4 bunchgrass, Pleuraphis rigida; and slightly reduced the cover of C3 drought-deciduous shrubs. Thus, we generally found no effect of elevated [CO2] on plant communities in this arid ecosystem. Extended drought, slow plant growth rates, and highly episodic germination and recruitment of new individuals explain the lack of strong perennial plant community shifts after a decade of elevated [CO2]. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Impact of elevated CO2 on a Florida Scrub-oak Ecosystems

Energy Technology Data Exchange (ETDEWEB)

Drake, Bert G

2013-01-01

Since May of 1996, we have conducted an experiment in Florida Scrub Oak to determine the impact of elevated atmospheric CO2 and climate change on carbon, water, and nutrient cycling in this important terrestrial ecosystem. Florida scrub oak is the name for a collective of species occupying much of the Florida peninsula. The dominant tree species are oaks and the dwarf structure of this community makes it an excellent system in which to test hypotheses regarding the potential capacity of woody ecosystems to assimilate and sequester anthropogenic carbon. Scrub oak is fire dependent with a return cycle of 10-15 years, a time which would permit an experiment to follow the entire cycle. Our site is located on Cape Canaveral at the Kennedy Space Center, Florida. After burning in 1995, we built 16 open top chambers, half of which have been fumigated with pure CO2 sufficient to raise the concentration around the plants to 350 ppm above ambient. In the intervening 10 years we have non destructively measured biomass of shoots and roots, ecosystem gas exchange using chambers and eddy flux, leaf photosynthesis and respiration, soil respiration, and relevant environmental factors such as soil water availability, temperature, light, etc. The overwhelming result from analysis of our extensive data base is that elevated CO2 has had a profound impact on this ecosystem that, overall, has resulted in increased carbon accumulation in plant shoots, roots and litter. Our measurements of net ecosystem gas exchange also indicate that the ecosystem has accumulated carbon much in excess of the increased biomass or soil carbon suggesting a substantial export of carbon through the porous, sandy soil into the water table several meters below the surface. A major discovery is the powerful interaction between the stimulation of growth, photosynthesis, and respiration by elevated CO2 and other environmental factors particularly precipitation and nitrogen. Our measurements focused attention on

DOES SOIL CO2 EFFLUX ACCLIMATIZETO ELEVATED TEMPERATURE AND CO2 DURING LONG-TERM TREATMENT OF DOUGLAS-FIR SEEDLINGS?

Science.gov (United States)

We investigated the effects of elevated soil temperature and atmospheric CO2 efflux (SCE) during the third an fourth years of study. We hypothesized that elevated temperature would stimulate SCE, and elevated CO2 would also stimulate SCE with the stimulation being greater at hig...

Simulation of spring wheat responses to elevated CO2 and temperature by using CERES-wheat crop model

Directory of Open Access Journals (Sweden)

H. LAURILA

2008-12-01

Full Text Available The CERES-wheat crop simulation model was used to estimate the changes in phenological development and yield production of spring wheat (Triticum aestivum L., cv. Polkka under different temperature and CO2 growing conditions. The effects of elevated temperature (3-4°C and CO2 concentration (700 ppm as expected for Finland in 2100 were simulated. The model was calibrated for long-day growing conditions in Finland. The CERES-wheat genetic coefficients for cv. Polkka were calibrated by using the MTT Agrifood Research Finland (MTT official variety trial data (1985-1990. Crop phenological development and yield measurements from open-top chamber experiments with ambient and elevated temperature and CO2 treatments were used to validate the model. Simulated mean grain yield under ambient temperature and CO2 conditions was 6.16 t ha-1 for potential growth (4.49 t ha-1 non-potential and 5.47 t ha-1 for the observed average yield (1992-1994 in ambient open-top chamber conditions. The simulated potential grain yield increased under elevated CO2 (700 ppm to 142% (167% non-potential from the simulated reference yield (100%, ambient temperature and CO2 350 ppm. Simulations for current sowing date and elevated temperature (3°C indicate accelerated anthesis and full maturity. According to the model estimations, potential yield decreased on average to 80.4% (76.8% non-potential due to temperature increase from the simulated reference. When modelling the concurrent elevated temperature and CO2 interaction, the increase in grain yield due to elevated CO2 was reduced by the elevated temperature. The combined CO2 and temperature effect increased the grain yield to 106% for potential growth (122% non-potential compared to the reference. Simulating the effects of earlier sowing, the potential grain yield increased under elevated temperature and CO2 conditions to 178% (15 days earlier sowing from 15 May, 700 ppm CO2, 3°C from the reference. Simulation results suggest

Gas exchange, growth, and defense responses of invasive Alliaria petiolata (Brassicaceae) and native Geum vernum (Rosaceae) to elevated atmospheric CO2 and warm spring temperatures.

Science.gov (United States)

Anderson, Laurel J; Cipollini, Don

2013-08-01

Global increases in atmospheric CO2 and temperature may interact in complex ways to influence plant physiology and growth, particularly for species that grow in cool, early spring conditions in temperate forests. Plant species may also vary in their responses to environmental changes; fast-growing invasives may be more responsive to rising CO2 than natives and may increase production of allelopathic compounds under these conditions, altering species' competitive interactions. We examined growth and physiological responses of Alliaria petiolata, an allelopathic, invasive herb, and Geum vernum, a co-occurring native herb, to ambient and elevated spring temperatures and atmospheric CO2 conditions in a factorial growth chamber experiment. At 5 wk, leaves were larger at high temperature, and shoot biomass increased under elevated CO2 only at high temperature in both species. As temperatures gradually warmed to simulate seasonal progression, G. vernum became responsive to CO2 at both temperatures, whereas A. petiolata continued to respond to elevated CO2 only at high temperature. Elevated CO2 increased thickness and decreased nitrogen concentrations in leaves of both species. Alliaria petiolata showed photosynthetic downregulation at elevated CO2, whereas G. vernum photosynthesis increased at elevated temperature. Flavonoid and cyanide concentrations decreased significantly in A. petiolata leaves in the elevated CO2 and temperature treatment. Total glucosinolate concentrations and trypsin inhibitor activities did not vary among treatments. Future elevated spring temperatures and CO2 will interact to stimulate growth for A. petiolata and G. vernum, but there may be reduced allelochemical effects in A. petiolata.

Effects of Single and Multifactor Treatments with Elevated Temperature, CO2 and Ozone on Oilseed Rape and Barley

DEFF Research Database (Denmark)

Clausen, Sabine Karin; Frenck, Georg; van der Linden, Leon Gareth

2011-01-01

We investigated the effect of elevated [CO2], [O3] and temperature on plant productivity and if these climate factors interacted with each other in multifactor treatments. The climate effects were studied in 14 different cultivars/lines of European spring oilseed rape (Brassica napus L.) and spring...... barley (Hordeum vulgare L.). Seven genotypes of each species were cultivated in six single- and multifactor treatments with ambient or elevated CO2 (385 ppm and 700 ppm), O3 (20 ppb and 60 ppb) and temperature (12/19 °C and 17/24 °C). Growth and production parameters were measured. Elevated CO2 increased....... A significantly decreased yield and thousand grain weight was also seen in barley due to elevated O3. The multifactor combination of elevated CO2, O3 and temperature showed a decrease in growth and production in the two species, though not statistically significant for all parameters. This trend suggests...

Growth performance and survival of larval Atlantic herring, under the combined effects of elevated temperatures and CO2.

Directory of Open Access Journals (Sweden)

Michael Sswat

Full Text Available In the coming decades, environmental change like warming and acidification will affect life in the ocean. While data on single stressor effects on fish are accumulating rapidly, we still know relatively little about interactive effects of multiple drivers. Of particular concern in this context are the early life stages of fish, for which direct effects of increased CO2 on growth and development have been observed. Whether these effects are further modified by elevated temperature was investigated here for the larvae of Atlantic herring (Clupea harengus, a commercially important fish species. Over a period of 32 days, larval survival, growth in size and weight, and instantaneous growth rate were assessed in a crossed experimental design of two temperatures (10°C and 12°C with two CO2 levels (400 μatm and 900 μatm CO2 at food levels mimicking natural levels using natural prey. Elevated temperature alone led to increased swimming activity, as well as decreased survival and instantaneous growth rate (Gi. The comparatively high sensitivity to elevated temperature in this study may have been influenced by low food levels offered to the larvae. Larval size, Gi and swimming activity were not affected by CO2, indicating tolerance of this species to projected "end of the century" CO2 levels. A synergistic effect of elevated temperature and CO2 was found for larval weight, where no effect of elevated CO2 concentrations was detected in the 12°C treatment, but a negative CO2 effect was found in the 10°C treatment. Contrasting CO2 effects were found for survival between the two temperatures. Under ambient CO2 conditions survival was increased at 12°C compared to 10°C. In general, CO2 effects were minor and considered negligible compared to the effect of temperature under these mimicked natural food conditions. These findings emphasize the need to include biotic factors such as energy supply via prey availability in future studies on interactive

Drought responses of two gymnosperm species with contrasting stomatal regulation strategies under elevated [CO2] and temperature.

Science.gov (United States)

Duan, Honglang; O'Grady, Anthony P; Duursma, Remko A; Choat, Brendan; Huang, Guomin; Smith, Renee A; Jiang, Yanan; Tissue, David T

2015-07-01

Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response to drought as a function of [CO2] and temperature. Both species were grown in two [CO2] (C(a) (ambient, 400 μl l(-1)) and C(e) (elevated, 640 μl l(-1))) and two temperature (T(a) (ambient) and T(e) (ambient +4 °C)) treatments in a sun-lit glasshouse under well-watered conditions. Drought plants were then exposed to a progressive drought until mortality. Prior to mortality, extensive xylem cavitation occurred in both species, but significant depletion of non-structural carbohydrates was not observed in either species. Te resulted in faster mortality in P. radiata, but it did not modify the time-to-mortality in C. rhomboidea. C(e) did not delay the time-to-mortality in either species under drought or T(e) treatments. In summary, elevated temperature (+4 °C) had greater influence than elevated [CO2] (+240 μl l(-1)) on drought responses of the two studied gymnosperm species, while stomatal regulation strategies did not generally affect the relative contributions of hydraulic failure and carbohydrate depletion to mortality under severe drought. �

Virus infection mediates the effects of elevated CO2 on plants and vectors

Science.gov (United States)

Trębicki, Piotr; Vandegeer, Rebecca K.; Bosque-Pérez, Nilsa A.; Powell, Kevin S.; Dader, Beatriz; Freeman, Angela J.; Yen, Alan L.; Fitzgerald, Glenn J.; Luck, Jo E.

2016-03-01

Atmospheric carbon dioxide (CO2) concentration has increased significantly and is projected to double by 2100. To increase current food production levels, understanding how pests and diseases respond to future climate driven by increasing CO2 is imperative. We investigated the effects of elevated CO2 (eCO2) on the interactions among wheat (cv. Yitpi), Barley yellow dwarf virus and an important pest and virus vector, the bird cherry-oat aphid (Rhopalosiphum padi), by examining aphid life history, feeding behavior and plant physiology and biochemistry. Our results showed for the first time that virus infection can mediate effects of eCO2 on plants and pathogen vectors. Changes in plant N concentration influenced aphid life history and behavior, and N concentration was affected by virus infection under eCO2. We observed a reduction in aphid population size and increased feeding damage on noninfected plants under eCO2 but no changes to population and feeding on virus-infected plants irrespective of CO2 treatment. We expect potentially lower future aphid populations on noninfected plants but no change or increased aphid populations on virus-infected plants therefore subsequent virus spread. Our findings underscore the complexity of interactions between plants, insects and viruses under future climate with implications for plant disease epidemiology and crop production.

Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis

NARCIS (Netherlands)

Graaff, de M.A.; Groenigen, van K.J.; Six, J.; Hungate, B.; Kessel, van C.

2006-01-01

free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO2 on nutrient cycling in terrestrial ecosystems. Using meta-analytic techniques, we summarized the results of 117 studies on plant biomass production,

Transcriptional reprogramming and stimulation of leaf respiration by elevated CO2 concentration is diminished, but not eliminated, under limiting nitrogen supply.

Science.gov (United States)

Markelz, R J Cody; Lai, Lisa X; Vosseler, Lauren N; Leakey, Andrew D B

2014-04-01

Plant respiration responses to elevated CO2 concentration ( [CO2 ] ) have been studied for three decades without consensus about the mechanism of response. Positive effects of elevated [CO2 ] on leaf respiration have been attributed to greater substrate supply resulting from stimulated photosynthesis. Negative effects of elevated [CO2 ] on leaf respiration have been attributed to reduced demand for energy for protein turnover assumed to result from lower leaf N content. Arabidopsis thaliana was grown in ambient (370 ppm) and elevated (750 ppm) [CO2 ] with limiting and ample N availabilities. The stimulation of leaf dark respiration was attenuated in limiting N (+12%) compared with ample N supply (+30%). This response was associated with smaller stimulation of photosynthetic CO2 uptake, but not interactive effects of elevated CO2 and N supply on leaf protein, amino acids or specific leaf area. Elevated [CO2 ] also resulted in greater abundance of transcripts for many components of the respiratory pathway. A greater transcriptional response to elevated [CO2 ] was observed in ample N supply at midday versus midnight, consistent with reports that protein synthesis is greatest during the day. Greater foliar expression of respiratory genes under elevated [CO2 ] has now been observed in diverse herbaceous species, suggesting a widely conserved response. © 2013 John Wiley & Sons Ltd.

Interactive effect of elevated pCO₂ and temperature on the larval development of an inter-tidal organism, Balanus amphitrite Darwin (Cirripedia: Thoracica)

Digital Repository Service at National Institute of Oceanography (India)

Baragi, L.V.; Anil, A.C.

selected based on present day pCO2 (~400 µatm) and predicted concentration for the year 2100 (~750 µatm) (Stocker et al., 2013). Four treatments were used in this study: (1) Control treatment - ambient temperature (~30 °C) and ambient pCO2 (~400 µatm); (2...) Elevated pCO2 treatment - ambient temperature (~30 °C) and elevated pCO2 (~750 µatm); (3) Elevated temperature treatment - elevated temperature (~34 °C) and ambient pCO2 (~400 µatm); and (4) Synergistic treatment - elevated temperature (~34 °C...

Plant-plant interactions mediate the plastic and genotypic response of Plantago asiatica to CO2 : an experiment with plant populations from naturally high CO2 areas

NARCIS (Netherlands)

van Loon, Marloes P; Rietkerk, Max; Dekker, Stefan C; Hikosaka, Kouki; Ueda, Miki U; Anten, Niels P R

2016-01-01

Background and Aims The rising atmospheric CO2 concentration ([CO2]) is a ubiquitous selective force that may strongly impact species distribution and vegetation functioning. Plant–plant interactions could mediate the trajectory of vegetation responses to elevated [CO2], because some plants may

How light, temperature, and measurement and growth [CO2] interactively control isoprene emission in hybrid aspen.

Science.gov (United States)

Niinemets, Ülo; Sun, Zhihong

2015-02-01

Plant isoprene emissions have been modelled assuming independent controls by light, temperature and atmospheric [CO2]. However, the isoprene emission rate is ultimately controlled by the pool size of its immediate substrate, dimethylallyl diphosphate (DMADP), and isoprene synthase activity, implying that the environmental controls might interact. In addition, acclimation to growth [CO2] can shift the share of the control by DMADP pool size and isoprene synthase activity, and thereby alter the environmental sensitivity. Environmental controls of isoprene emission were studied in hybrid aspen (Populus tremula × Populus tremuloides) saplings acclimated either to ambient [CO2] of 380 μmol mol(-1) or elevated [CO2] of 780 μmol mol(-1). The data demonstrated strong interactive effects of environmental drivers and growth [CO2] on isoprene emissions. Light enhancement of isoprene emission was the greatest at intermediate temperatures and was greater in elevated-[CO2]-grown plants, indicating greater enhancement of the DMADP supply. The optimum temperature for isoprene emission was higher at lower light, suggesting activation of alternative DMADP sinks at higher light. In addition, [CO2] inhibition of isoprene emission was lost at a higher temperature with particularly strong effects in elevated-[CO2]-grown plants. Nevertheless, DMADP pool size was still predicted to more strongly control isoprene emission at higher temperatures in elevated-[CO2]-grown plants. We argue that interactive environmental controls and acclimation to growth [CO2] should be incorporated in future isoprene emission models at the level of DMADP pool size. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Elevated CO2 concentration around alfalfa nodules increases N2 fixation

OpenAIRE

Fischinger, Stephanie A.; Hristozkova, Marieta; Mainassara, Zaman-Allah; Schulze, Joachim

2009-01-01

Nodule CO2 fixation via PEPC provides malate for bacteroids and oxaloacetate for N assimilation. The process is therefore of central importance for efficient nitrogen fixation. Nodule CO2 fixation is known to depend on external CO2 concentration. The hypothesis of the present paper was that nitrogen fixation in alfalfa plants is enhanced when the nodules are exposed to elevated CO2 concentrations. Therefore nodulated plants of alfalfa were grown in a hydroponic system that allowed separate ae...

Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

Science.gov (United States)

Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

2010-05-01

Increasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long-term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root-free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate-induced respiration response after glucose and/or yeast extract addition to the soil. We evaluated the effect of elevated CO2 on b-glucosidase, chitinase, phosphatase, and sulfatase to estimate the potential enzyme activity after soil amendment with glucose and nutrients. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ-values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivumyeast extract then for those growing on glucose, i.e. the effect of elevated CO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). After adding glucose, enzyme activities under elevated CO2 were 1.2-1.9-fold higher than under ambient CO2. This indicates the increased activity of microorganisms, which leads to accelerated C turnover in soil under elevated CO2. Our results clearly showed that the functional characteristics of the soil microbial community (i.e. specific growth rates and enzymes activity) rather than total microbial biomass

Physiological acclimation dampens initial effects of elevated temperature and atmospheric CO2 concentration in mature boreal Norway spruce.

Science.gov (United States)

Lamba, Shubhangi; Hall, Marianne; Räntfors, Mats; Chaudhary, Nitin; Linder, Sune; Way, Danielle; Uddling, Johan; Wallin, Göran

2018-02-01

Physiological processes of terrestrial plants regulate the land-atmosphere exchange of carbon, water, and energy, yet few studies have explored the acclimation responses of mature boreal conifer trees to climate change. Here we explored the acclimation responses of photosynthesis, respiration, and stomatal conductance to elevated temperature and/or CO 2 concentration ([CO 2 ]) in a 3-year field experiment with mature boreal Norway spruce. We found that elevated [CO 2 ] decreased photosynthetic carboxylation capacity (-23% at 25 °C) and increased shoot respiration (+64% at 15 °C), while warming had no significant effects. Shoot respiration, but not photosynthetic capacity, exhibited seasonal acclimation. Stomatal conductance at light saturation and a vapour pressure deficit of 1 kPa was unaffected by elevated [CO 2 ] but significantly decreased (-27%) by warming, and the ratio of intercellular to ambient [CO 2 ] was enhanced (+17%) by elevated [CO 2 ] and decreased (-12%) by warming. Many of these responses differ from those typically observed in temperate tree species. Our results show that long-term physiological acclimation dampens the initial stimulation of plant net carbon assimilation to elevated [CO 2 ], and of plant water use to warming. Models that do not account for these responses may thus overestimate the impacts of climate change on future boreal vegetation-atmosphere interactions. © 2017 John Wiley & Sons Ltd.

Sex-specific responses of Populus yunnanensis exposed to elevated CO{sub 2} and salinity

Energy Technology Data Exchange (ETDEWEB)

Ling Li; Yuanbin Zhang; Chunyang Li [Chinese Academy of Sciences. Chengdu Institute of Biology, Chengdu (Switzerland); Jianxun Luo, Sichuan Academy of Forestry, Chengdu (Switzerland)); Korpelainen, H. [Univ. of Helsinki. Dept. of Agricultural Sciences, Helsinki (Finland)

2013-04-15

Populus yunnanensis Dode., a native dioecious woody plant in southwestern China, was employed as a model species to study sex-specific morphological, physiological and biochemical responses to elevated CO{sub 2} and salinity. To investigate the effects of elevated CO{sub 2}, salinity and their combination, the cuttings were exposed to two CO{sub 2} regimes (ambient CO{sub 2} and double ambient CO{sub 2}) and two salt treatments in growth chambers. Males exhibited greater downregulation of net photosynthesis rate (A{sub net}) and carboxylation efficiency (CE) than females at elevated CO{sub 2}, whereas these sexual differences were lessened under salt stress. On the other hand, salinity induced a higher decrease in Anet and CE, more growth inhibition and leaf Cl{sup -} accumulation and more damage to cell organelles in females than in males, whereas the sexual differences in photosynthesis and growth were lessened at elevated CO{sub 2}. Moreover, elevated CO{sub 2} exacerbated membrane lipid peroxidation and organelle damage in females but not in males under salt stress. Our results indicated that: (1) females are more sensitive and suffer from greater negative effects than do males under salt stress, and elevated CO{sub 2} lessens the sexual differences in photosynthesis and growth under salt stress; (2) elevated CO{sub 2} tends to aggravate the negative effects of salinity in females; and (3) sex-specific reactions under the combination of elevated CO{sub 2} and salinity are distinct from single-stress responses. Therefore, these results provide evidence for different adaptive responses between plants of different sexes exposed to elevated CO{sub 2} and salinity. (Author)

Virus infection mediates the effects of elevated CO2 on plants and vectors

Science.gov (United States)

Trębicki, Piotr; Vandegeer, Rebecca K.; Bosque-Pérez, Nilsa A.; Powell, Kevin S.; Dader, Beatriz; Freeman, Angela J.; Yen, Alan L.; Fitzgerald, Glenn J.; Luck, Jo E.

2016-01-01

Atmospheric carbon dioxide (CO2) concentration has increased significantly and is projected to double by 2100. To increase current food production levels, understanding how pests and diseases respond to future climate driven by increasing CO2 is imperative. We investigated the effects of elevated CO2 (eCO2) on the interactions among wheat (cv. Yitpi), Barley yellow dwarf virus and an important pest and virus vector, the bird cherry-oat aphid (Rhopalosiphum padi), by examining aphid life history, feeding behavior and plant physiology and biochemistry. Our results showed for the first time that virus infection can mediate effects of eCO2 on plants and pathogen vectors. Changes in plant N concentration influenced aphid life history and behavior, and N concentration was affected by virus infection under eCO2. We observed a reduction in aphid population size and increased feeding damage on noninfected plants under eCO2 but no changes to population and feeding on virus-infected plants irrespective of CO2 treatment. We expect potentially lower future aphid populations on noninfected plants but no change or increased aphid populations on virus-infected plants therefore subsequent virus spread. Our findings underscore the complexity of interactions between plants, insects and viruses under future climate with implications for plant disease epidemiology and crop production. PMID:26941044

Elevated temperature and CO2 concentration effects on xylem anatomy of Scots pine

International Nuclear Information System (INIS)

Kilpelainen, A.; Gerendiain, A.Z.; Luostarinen, K.; Peltola, H.; Kellomaki, S.

2007-01-01

The effects of carbon dioxide (CO 2 ) concentrations and elevated temperatures on the xylem anatomy of 20-year old Scots pine trees were investigated. The experiment was conducted in 16 chambers containing 4 trees each with a factorial combination of both ambient and elevated CO 2 concentrations and 2 different temperature regimes. CO 2 concentrations were doubled with a corresponding increase of between 2 and 6 degrees C according to each season over a period of 6 years. The study showed that elevated CO 2 concentrations increased the ring width in 4 of the 6 analyzed treatment years. Earlywood width increased during the first 2 years of the experiment, while latewood width increased during the third year of the study. The study also showed that the tracheid walls in both the latewood and earlywood samples were thicker when either temperature levels or CO 2 levels were increased. It was noted that combined CO 2 and temperature elevations resulted in thinner tracheid walls. However, latewood tracheid lumen diameters were larger in all CO 2 and temperature treatments than trees grown in ambient conditions. It was concluded that xylem anatomy was impacted more by increases in temperature than by elevated CO 2 concentrations. 48 refs., 2 tabs., 6 figs

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

Directory of Open Access Journals (Sweden)

José C. Ramalho

2018-03-01

Full Text Available Climate changes, mostly related to high temperature, are predicted to have major negative impacts on coffee crop yield and bean quality. Recent studies revealed that elevated air [CO2] mitigates the impact of heat on leaf physiology. However, the extent of the interaction between elevated air [CO2] and heat on coffee bean quality was never addressed. In this study, the single and combined impacts of enhanced [CO2] and temperature in beans of Coffea arabica cv. Icatu were evaluated. Plants were grown at 380 or 700 μL CO2 L-1 air, and then submitted to a gradual temperature rise from 25°C up to 40°C during ca. 4 months. Fruits were harvested at 25°C, and in the ranges of 30–35 or 36–40°C, and bean physical and chemical attributes with potential implications on quality were then examined. These included: color, phenolic content, soluble solids, chlorogenic, caffeic and p-coumaric acids, caffeine, trigonelline, lipids, and minerals. Most of these parameters were mainly affected by temperature (although without a strong negative impact on bean quality, and only marginally, if at all, by elevated [CO2]. However, the [CO2] vs. temperature interaction strongly attenuated some of the negative impacts promoted by heat (e.g., total chlorogenic acids, thus maintaining the bean characteristics closer to those obtained under adequate temperature conditions (e.g., soluble solids, caffeic and p-coumaric acids, trigonelline, chroma, Hue angle, and color index, and increasing desirable features (acidity. Fatty acid and mineral pools remained quite stable, with only few modifications due to elevated air [CO2] (e.g., phosphorous and/or heat. In conclusion, exposure to high temperature in the last stages of fruit maturation did not strongly depreciate bean quality, under the conditions of unrestricted water supply and moderate irradiance. Furthermore, the superimposition of elevated air [CO2] contributed to preserve bean quality by modifying and mitigating

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

Science.gov (United States)

Ramalho, José C.; Pais, Isabel P.; Leitão, António E.; Guerra, Mauro; Reboredo, Fernando H.; Máguas, Cristina M.; Carvalho, Maria L.; Scotti-Campos, Paula; Ribeiro-Barros, Ana I.; Lidon, Fernando J. C.; DaMatta, Fábio M.

2018-01-01

Climate changes, mostly related to high temperature, are predicted to have major negative impacts on coffee crop yield and bean quality. Recent studies revealed that elevated air [CO2] mitigates the impact of heat on leaf physiology. However, the extent of the interaction between elevated air [CO2] and heat on coffee bean quality was never addressed. In this study, the single and combined impacts of enhanced [CO2] and temperature in beans of Coffea arabica cv. Icatu were evaluated. Plants were grown at 380 or 700 μL CO2 L-1 air, and then submitted to a gradual temperature rise from 25°C up to 40°C during ca. 4 months. Fruits were harvested at 25°C, and in the ranges of 30–35 or 36–40°C, and bean physical and chemical attributes with potential implications on quality were then examined. These included: color, phenolic content, soluble solids, chlorogenic, caffeic and p-coumaric acids, caffeine, trigonelline, lipids, and minerals. Most of these parameters were mainly affected by temperature (although without a strong negative impact on bean quality), and only marginally, if at all, by elevated [CO2]. However, the [CO2] vs. temperature interaction strongly attenuated some of the negative impacts promoted by heat (e.g., total chlorogenic acids), thus maintaining the bean characteristics closer to those obtained under adequate temperature conditions (e.g., soluble solids, caffeic and p-coumaric acids, trigonelline, chroma, Hue angle, and color index), and increasing desirable features (acidity). Fatty acid and mineral pools remained quite stable, with only few modifications due to elevated air [CO2] (e.g., phosphorous) and/or heat. In conclusion, exposure to high temperature in the last stages of fruit maturation did not strongly depreciate bean quality, under the conditions of unrestricted water supply and moderate irradiance. Furthermore, the superimposition of elevated air [CO2] contributed to preserve bean quality by modifying and mitigating the heat impact

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

Science.gov (United States)

Ramalho, José C; Pais, Isabel P; Leitão, António E; Guerra, Mauro; Reboredo, Fernando H; Máguas, Cristina M; Carvalho, Maria L; Scotti-Campos, Paula; Ribeiro-Barros, Ana I; Lidon, Fernando J C; DaMatta, Fábio M

2018-01-01

Climate changes, mostly related to high temperature, are predicted to have major negative impacts on coffee crop yield and bean quality. Recent studies revealed that elevated air [CO 2 ] mitigates the impact of heat on leaf physiology. However, the extent of the interaction between elevated air [CO 2 ] and heat on coffee bean quality was never addressed. In this study, the single and combined impacts of enhanced [CO 2 ] and temperature in beans of Coffea arabica cv. Icatu were evaluated. Plants were grown at 380 or 700 μL CO 2 L -1 air, and then submitted to a gradual temperature rise from 25°C up to 40°C during ca. 4 months. Fruits were harvested at 25°C, and in the ranges of 30-35 or 36-40°C, and bean physical and chemical attributes with potential implications on quality were then examined. These included: color, phenolic content, soluble solids, chlorogenic, caffeic and p -coumaric acids, caffeine, trigonelline, lipids, and minerals. Most of these parameters were mainly affected by temperature (although without a strong negative impact on bean quality), and only marginally, if at all, by elevated [CO 2 ]. However, the [CO 2 ] vs. temperature interaction strongly attenuated some of the negative impacts promoted by heat (e.g., total chlorogenic acids), thus maintaining the bean characteristics closer to those obtained under adequate temperature conditions (e.g., soluble solids, caffeic and p -coumaric acids, trigonelline, chroma, Hue angle, and color index), and increasing desirable features (acidity). Fatty acid and mineral pools remained quite stable, with only few modifications due to elevated air [CO 2 ] (e.g., phosphorous) and/or heat. In conclusion, exposure to high temperature in the last stages of fruit maturation did not strongly depreciate bean quality, under the conditions of unrestricted water supply and moderate irradiance. Furthermore, the superimposition of elevated air [CO 2 ] contributed to preserve bean quality by modifying and mitigating

Effects of elevated CO

NARCIS (Netherlands)

Xue, Sha; Yang, Xiaomei; Liu, Guobin; Gai, Lingtong; Zhang, Changsheng; Ritsema, Coen J.; Geissen, Violette

2017-01-01

Elevated CO₂ and drought are key consequences of climate change and affect soil processes and plant growth. This study investigated the effects of elevated CO₂ and drought on the microbial biomass and enzymatic activities in the rhizospheres of Bothriochloa ischaemum and

CO2 elevation improves photosynthetic performance in progressive warming environment in white birch seedlings [v1; ref status: indexed, http://f1000r.es/up

Directory of Open Access Journals (Sweden)

Shouren Zhang

2013-01-01

Full Text Available White birch (Betula paperifera Mash seedlings were exposed to progressively warming in greenhouses under ambient and elevated CO2 concentrations for 5 months to explore boreal tree species’ potential capacity to acclimate to global climate warming and CO2 elevation. In situ foliar gas exchange, in vivo carboxylation characteristics and chlorophyll fluorescence were measured at temperatures of 26oC and 37oC. Elevated CO2 significantly increased net photosynthetic rate (Pn at both measurement temperatures, and Pn at 37oC was higher than that at 26oC under elevated CO2. Stomatal conductance (gs was lower at 37oC than at 26oC, while transpiration rate (E was higher at 37oC than that at 26oC. Elevated CO2 significantly increased instantaneous water-use efficiency (WUE at both 26oC and 37oC, but WUE was markedly enhanced at 37oC under elevated CO2. The effect of temperature on maximal carboxylation rate (Vcmax, PAR-saturated electron transport rate (Jmax and triose phosphate utilization (TPU varied with CO2, and the Vcmax and Jmax were significantly higher at 37oC than at 26oC under elevated CO2. However, there were no significant interactive effects of CO2 and temperature on TPU. The actual photochemical efficiency of PSII (DF/ Fm’, total photosynthetic linear electron transport rate through PSII (JT and the partitioning of JT to carboxylation (Jc were higher at 37oC than at 26oC under elevated CO2. Elevated CO2 significantly suppressed the partitioning of JT to oxygenation (Jo/JT. The data suggest that the CO2 elevation and progressive warming greatly enhanced photosynthesis in white birch seedlings in an interactive fashion.

ELEVATED CO{sub 2} IN A PROTOTYPE FREE-AIR CO{sub 2} ENRICHMENT FACILITY AFFECTS PHOTOSYNTHETIC NITROGEN RELATIONS IN A MATURING PINE FOREST

Energy Technology Data Exchange (ETDEWEB)

ELLSWORTH,D.S.; LA ROCHE,J.; HENDREY,G.R.

1998-03-01

A maturing loblolly pine (Pinus taeda L.) forest was exposed to elevated CO{sub 2} in the natural environment in a perturbation study conducted over three seasons using the free-air CO{sub 2} enrichment (FACE) technique. At the time measurements were begun in this study, the pine canopy was comprised entirely of foliage which had developed under elevated CO{sub 2} conditions (atmospheric [CO{sub 2}] {approx} 550 {micro}mol mol{sup {minus}1}). Measurements of leaf photosynthetic responses to CO{sub 2} were taken to examine the effects of elevated CO{sub 2} on photosynthetic N nutrition in a pine canopy under elevated CO{sub 2}. Photosynthetic CO{sub 2} response curves (A-c{sub i} curves) were similar in FACE trees under elevated CO{sub 2} compared with counterpart trees in ambient plots for the first foliage cohort produced in the second season of CO{sub 2} exposure, with changes in curve form detected in the foliage cohorts subsequently produced under elevated CO{sub 2}. Differences in the functional relationship between carboxylation rate and N{sub a} suggest that for a given N{sub a} allocated among successive cohorts of foliage in the upper canopy, V{sub c max} was 17% lower in FACE versus Ambient trees. The authors also found that foliar Rubisco content per unit total protein derived from Western blot analysis was lower in late-season foliage in FACE foliage compared with ambient-grown foliage. The results illustrate a potentially important mode of physiological adjustment to growth conditions that may operate in forest canopies. Their findings suggest that mature loblolly pine trees growing in the field may have the capacity for shifts in intrinsic nitrogen utilization for photosynthesis under elevated CO{sub 2} that are not dependent on changes in leaf N. While carboxylation efficiency per unit N apparently decreased under elevated CO{sub 2}, photosynthetic rates in trees at elevated CO{sub 2} concentrations {approx} 550 pmol mol{sub {minus}1} are still

Plant growth responses to elevated atmospheric CO2 are increased by phosphorus sufficiency but not by arbuscular mycorrhizas.

Science.gov (United States)

Jakobsen, Iver; Smith, Sally E; Smith, F Andrew; Watts-Williams, Stephanie J; Clausen, Signe S; Grønlund, Mette

2016-11-01

Capturing the full growth potential in crops under future elevated CO 2 (eCO 2 ) concentrations would be facilitated by improved understanding of eCO 2 effects on uptake and use of mineral nutrients. This study investigates interactions of eCO 2 , soil phosphorus (P), and arbuscular mycorrhizal (AM) symbiosis in Medicago truncatula and Brachypodium distachyon grown under the same conditions. The focus was on eCO 2 effects on vegetative growth, efficiency in acquisition and use of P, and expression of phosphate transporter (PT) genes. Growth responses to eCO 2 were positive at P sufficiency, but under low-P conditions they ranged from non-significant in M. truncatula to highly significant in B. distachyon Growth of M. truncatula was increased by AM at low P conditions at both CO 2 levels and eCO 2 ×AM interactions were sparse. Elevated CO 2 had small effects on P acquisition, but enhanced conversion of tissue P into biomass. Expression of PT genes was influenced by eCO 2 , but effects were inconsistent across genes and species. The ability of eCO 2 to partly mitigate P limitation-induced growth reductions in B. distachyon was associated with enhanced P use efficiency, and requirements for P fertilizers may not increase in such species in future CO 2 -rich climates. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Exposure to elevated pCO2 does not exacerbate reproductive suppression of Aurelia aurita jellyfish polyps in low oxygen environments

KAUST Repository

Treible, LM

2017-08-15

Eutrophication-induced hypoxia is one of the primary anthropogenic threats to coastal ecosystems. Under hypoxic conditions, a deficit of O2 and a surplus of CO2 will concurrently decrease pH, yet studies of hypoxia have seldom considered the potential interactions with elevated pCO2 (reduced pH). Previous studies on gelatinous organisms concluded that they are fairly robust to low oxygen and reduced pH conditions individually, yet the combination of stressors has only been examined for ephyrae. The goals of this study were to determine the individual and interactive effects of hypoxia and elevated pCO2 on the asexual reproduction and aerobic respiration rates of polyps of the scyphozoan Aurelia aurita during a manipulative experiment that ran for 36 d. pCO2 and pO2 were varied on a diel basis to closely mimic the diel conditions observed in the field. Exposure to low dissolved oxygen (DO) reduced asexual budding of polyps by ~50% relative to control conditions. Under hypoxic conditions, rates of respiration were elevated during an initial acclimation period (until Day 8), but respiration rates did not differ between DO levels under prolonged exposure. There was no significant effect of increased pCO2 on either asexual reproduction or aerobic respiration, suggesting that elevated pCO2 (reduced pH) did not exacerbate the negative reproductive effects of hypoxia on A. aurita polyps.

Exposure to elevated pCO2 does not exacerbate reproductive suppression of Aurelia aurita jellyfish polyps in low oxygen environments

KAUST Repository

Treible, LM; Pitt, KA; Klein, SG; Condon, RH

2017-01-01

Eutrophication-induced hypoxia is one of the primary anthropogenic threats to coastal ecosystems. Under hypoxic conditions, a deficit of O2 and a surplus of CO2 will concurrently decrease pH, yet studies of hypoxia have seldom considered the potential interactions with elevated pCO2 (reduced pH). Previous studies on gelatinous organisms concluded that they are fairly robust to low oxygen and reduced pH conditions individually, yet the combination of stressors has only been examined for ephyrae. The goals of this study were to determine the individual and interactive effects of hypoxia and elevated pCO2 on the asexual reproduction and aerobic respiration rates of polyps of the scyphozoan Aurelia aurita during a manipulative experiment that ran for 36 d. pCO2 and pO2 were varied on a diel basis to closely mimic the diel conditions observed in the field. Exposure to low dissolved oxygen (DO) reduced asexual budding of polyps by ~50% relative to control conditions. Under hypoxic conditions, rates of respiration were elevated during an initial acclimation period (until Day 8), but respiration rates did not differ between DO levels under prolonged exposure. There was no significant effect of increased pCO2 on either asexual reproduction or aerobic respiration, suggesting that elevated pCO2 (reduced pH) did not exacerbate the negative reproductive effects of hypoxia on A. aurita polyps.

Biochar addition induced the same plant responses as elevated CO2 in mine spoil.

Science.gov (United States)

Zhang, Yaling; Drigo, Barbara; Bai, Shahla Hosseini; Menke, Carl; Zhang, Manyun; Xu, Zhihong

2018-01-01

Nitrogen (N) limitation is one of the major constrain factors for biochar in improving plant growth, the same for elevated atmospheric carbon dioxide (CO 2 ). Hence, we hypothesized that (1) biochar would induce the same plant responses as elevated CO 2 under N-poor conditions; (2) elevated CO 2 would decrease the potential of biochar application in improving plant growth. To test these hypotheses, we assessed the effects of pinewood biochar, produced at three pyrolytic temperatures (650, 750 and 850 °C), on C and N allocation at the whole-plant level of three plant species (Austrostipa ramossissima, Dichelachne micrantha and Isolepis nodosa) grown in the N poor mine spoil under both ambient (400 μL L -1 ) and elevated (700 μL L -1 ) CO 2 concentrations. Our data showed that biochar addition (1) significantly decreased leaf total N and δ 15 N (P < 0.05); (2) decreased leaf total N and δ 15 N more pronouncedly than those of root; and (3) showed more pronounced effects on improving plant biomass under ambient CO 2 than under elevated CO 2 concentration. Hence, it remained a strong possibility that biochar addition induced the same plant physiological responses as elevated CO 2 in the N-deficient mine spoil. As expected, elevated CO 2 decreased the ability of biochar addition in improving plant growth.

Elevated CO{sub 2} in a prototype free-air CO{sub 2} enrichment facility affects photosynthetic nitrogen relations in a maturing pine forest

Energy Technology Data Exchange (ETDEWEB)

Ellsworth, D.S.; LaRoche, J.; Hendrey, G.R.

1998-03-01

A maturing loblolly pine (Pinus taeda L.) forest was exposed to elevated CO{sub 2} in the natural environment in a perturbation study conducted over three seasons using the free-air CO{sub 2} enrichment (FACE) technique. At the time measurements were begun in this study, the pine canopy was comprised entirely of foliage which had developed under elevated CO{sub 2} conditions (atmospheric CO{sub 2} {approx} 550 {micro}mol/mol{sup {minus}1}). Measurements of leaf photosynthetic responses to CO{sub 2} were taken to examine the effects of elevated CO{sub 2} on photosynthetic N nutrition in a pine canopy under elevated CO{sub 2}. Photosynthetic CO{sub 2} response curves (A-c{sub i} curves) were similar in FACE trees under elevated CO{sub 2} compared with counterpart trees in ambient plots for the first foliage cohort produced in the second season of CO{sub 2} exposure, with changes in curve form detected in the foliage cohorts subsequently produced under elevated CO{sub 2}. Differences in the functional relationship between carboxylation rate and N{sub a} suggest that for a given N{sub a} allocated among successive cohorts of foliage in the upper canopy, V{sub c max} was 17% lower in FACE versus Ambient trees. The authors also found that foliar Rubisco content per unit total protein derived from Western blot analysis was lower in late-season foliage in FACE foliage compared with ambient-grown foliage. The results illustrate a potentially important mode of physiological adjustment to growth conditions that may operate in forest canopies. Findings suggest that mature loblolly pine trees growing in the field may have the capacity for shifts in intrinsic nitrogen utilization for photosynthesis under elevated CO{sub 2} that are not dependent on changes in leaf N. Findings suggest a need for continued examination of internal feedbacks at the whole-tree and ecosystem level in forests that may influence long-term photosynthetic responses to elevated CO{sub 2}.

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

Institute of Scientific and Technical Information of China (English)

Yun-Zhou Qiao; Yuan-Bin Zhang; Kai-Yun Wang; Qian Wang; Qi-Zhuo Tian

2008-01-01

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient + 350 (=1= 25) μmol/mol) under two planting densities (28 or 84 plants/mz) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.

Elevated CO2 and O3t concentrations differentially affect selected groups of the fauna in temperate forest soils

Science.gov (United States)

Gladys I. Loranger; Kurt S. Pregitzer; John S. King

2004-01-01

Rising atmospheric CO2 concentrations may change soil fauna abundance. How increase of tropospheric ozone (O3t) concentration will modify these responses is still unknown. We have assessed independent and interactive effects of elevated [CO2] and [O3t] on selected groups of soil...

Effects of elevated CO2 on litter chemistry and subsequent invertebrate detritivore feeding responses.

Directory of Open Access Journals (Sweden)

Matthew W Dray

Full Text Available Elevated atmospheric CO2 can change foliar tissue chemistry. This alters leaf litter palatability to macroinvertebrate detritivores with consequences for decomposition, nutrient turnover, and food-web structure. Currently there is no consensus on the link between CO2 enrichment, litter chemistry, and macroinvertebrate-mediated leaf decomposition. To identify any unifying mechanisms, we presented eight invertebrate species from aquatic and terrestrial ecosystems with litter from Alnus glutinosa (common alder or Betula pendula (silver birch trees propagated under ambient (380 ppm or elevated (ambient +200 ppm CO2 concentrations. Alder litter was largely unaffected by CO2 enrichment, but birch litter from leaves grown under elevated CO2 had reduced nitrogen concentrations and greater C/N ratios. Invertebrates were provided individually with either (i two litter discs, one of each CO2 treatment ('choice', or (ii one litter disc of each CO2 treatment alone ('no-choice'. Consumption was recorded. Only Odontocerum albicorne showed a feeding preference in the choice test, consuming more ambient- than elevated-CO2 birch litter. Species' responses to alder were highly idiosyncratic in the no-choice test: Gammarus pulex and O. albicorne consumed more elevated-CO2 than ambient-CO2 litter, indicating compensatory feeding, while Oniscus asellus consumed more of the ambient-CO2 litter. No species responded to CO2 treatment when fed birch litter. Overall, these results show how elevated atmospheric CO2 can alter litter chemistry, affecting invertebrate feeding behaviour in species-specific ways. The data highlight the need for greater species-level information when predicting changes to detrital processing-a key ecosystem function-under atmospheric change.

Effects of elevated CO2 leaf diets on gypsy moth (Lepidoptera: Lymantriidae) respiration rates.

Science.gov (United States)

Foss, Anita R; Mattson, William J; Trier, Terry M

2013-06-01

Elevated levels of CO2 affect plant growth and leaf chemistry, which in turn can alter host plant suitability for insect herbivores. We examined the suitability of foliage from trees grown from seedlings since 1997 at Aspen FACE as diet for the gypsy moth (Lymantria dispar L.) Lepidoptera: Lymantriidae: paper birch (Betula papyrifera Marshall) in 2004-2005, and trembling aspen (Populus tremuloides Michaux) in 2006-2007, and measured consequent effects on larval respiration. Leaves were collected for diet and leaf chemistry (nutritional and secondary compound proxies) from trees grown under ambient (average 380 ppm) and elevated CO2 (average 560 ppm) conditions. Elevated CO2 did not significantly alter birch or aspen leaf chemistry compared with ambient levels with the exception that birch percent carbon in 2004 and aspen moisture content in 2006 were significantly lowered. Respiration rates were significantly higher (15-59%) for larvae reared on birch grown under elevated CO2 compared with ambient conditions, but were not different on two aspen clones, until larvae reached the fifth instar, when those consuming elevated CO2 leaves on clone 271 had lower (26%) respiration rates, and those consuming elevated CO2 leaves on clone 216 had higher (36%) respiration rates. However, elevated CO2 had no apparent effect on the respiration rates of pupae derived from larvae fed either birch or aspen leaves. Higher respiration rates for larvae fed diets grown under ambient or elevated CO2 demonstrates their lower efficiency of converting chemical energy of digested food stuffs extracted from such leaves into their biosynthetic processes.

Loblolly pine grown under elevated CO2 affects early instar pine sawfly performance.

Science.gov (United States)

Williams, R S; Lincoln, D E; Thomas, R B

1994-06-01

Seedlings of loblolly pine Pinus taeda (L.), were grown in open-topped field chambers under three CO 2 regimes: ambient, 150 μl l -1 CO 2 above ambient, and 300 μl l -1 CO 2 above ambient. A fourth, non-chambered ambient treatment was included to assess chamber effects. Needles were used in 96 h feeding trials to determine the performance of young, second instar larvae of loblolly pine's principal leaf herbivore, red-headed pine sawfly, Neodiprion lecontei (Fitch). The relative consumption rate of larvae significantly increased on plants grown under elevated CO 2 , and needles grown in the highest CO 2 regime were consumed 21% more rapidly than needles grown in ambient CO 2 . Both the significant decline in leaf nitrogen content and the substantial increase in leaf starch content contributed to a significant increase in the starch:nitrogen ratio in plants grown in elevated CO 2 . Insect consumption rate was negatively related to leaf nitrogen content and positively related to the starch:nitrogen ratio. Of the four volatile leaf monoterpenes measured, only β-pinene exhibited a significant CO 2 effect and declined in plants grown in elevated CO 2 . Although consumption changed, the relative growth rates of larvae were not different among CO 2 treatments. Despite lower nitrogen consumption rates by larvae feeding on the plants grown in elevated CO 2 , nitrogen accumulation rates were the same for all treatments due to a significant increase in nitrogen utilization efficiency. The ability of this insect to respond at an early, potentially susceptible larval stage to poorer food quality and declining levels of a leaf monoterpene suggest that changes in needle quality within pines in future elevated-CO 2 atmospheres may not especially affect young insects and that tree-feeding sawflies may respond in a manner similar to herb-feeding lepidopterans.

Effects of Elevated CO2 on the Swainsonine Chemotypes of Astragalus lentiginosus and Astragalus mollissimus.

Science.gov (United States)

Cook, Daniel; Gardner, Dale R; Pfister, James A; Stonecipher, Clinton A; Robins, Joseph G; Morgan, Jack A

2017-03-01

Rapid changes in the Earth's atmosphere and climate associated with human activity can have significant impacts on agriculture including livestock production. CO 2 concentration has risen from the industrial revolution to the current time, and is expected to continue to rise. Climatic changes alter physiological processes, growth, and development in numerous plant species, potentially changing concentrations of plant secondary compounds. These physiological changes may influence plant population density, growth, fitness, and toxin concentrations and thus influence the risk of toxic plants to grazing livestock. Locoweeds, swainsonine-containing Astragalus species, are one group of plants that may be influenced by climate change. We evaluated how two different swainsonine-containing Astragalus species responded to elevated CO 2 concentrations. Measurements of biomass, crude protein, water soluble carbohydrates and swainsonine concentrations were measured in two chemotypes (positive and negative for swainsonine) of each species after growth at CO 2 levels near present day and at projected future concentrations. Biomass and water soluble carbohydrate concentrations responded positively while crude protein concentrations responded negatively to elevated CO 2 in the two species. Swainsonine concentrations were not strongly affected by elevated CO 2 in the two species. In the different chemotypes, biomass responded negatively and crude protein concentrations responded positively in the swainsonine-positive plants compared to the swainsonine-negative plants. Ultimately, changes in CO 2 and endophyte status will likely alter multiple physiological responses in toxic plants such as locoweed, but it is difficult to predict how these changes will impact plant herbivore interactions.

Elevated temperature and CO{sub 2} concentration effects on xylem anatomy of Scots pine

Energy Technology Data Exchange (ETDEWEB)

Kilpelainen, A.; Gerendiain, A.Z.; Luostarinen, K.; Peltola, H.; Kellomaki, S. [Joensuu Univ., Joensuu (Finland). Faculty of Forestry

2007-09-15

The effects of carbon dioxide (CO{sub 2}) concentrations and elevated temperatures on the xylem anatomy of 20-year old Scots pine trees were investigated. The experiment was conducted in 16 chambers containing 4 trees each with a factorial combination of both ambient and elevated CO{sub 2} concentrations and 2 different temperature regimes. CO{sub 2} concentrations were doubled with a corresponding increase of between 2 and 6 degrees C according to each season over a period of 6 years. The study showed that elevated CO{sub 2} concentrations increased the ring width in 4 of the 6 analyzed treatment years. Earlywood width increased during the first 2 years of the experiment, while latewood width increased during the third year of the study. The study also showed that the tracheid walls in both the latewood and earlywood samples were thicker when either temperature levels or CO{sub 2} levels were increased. It was noted that combined CO{sub 2} and temperature elevations resulted in thinner tracheid walls. However, latewood tracheid lumen diameters were larger in all CO{sub 2} and temperature treatments than trees grown in ambient conditions. It was concluded that xylem anatomy was impacted more by increases in temperature than by elevated CO{sub 2} concentrations. 48 refs., 2 tabs., 6 figs.

Combined Effects of Elevated pCO2 and Warming Facilitate Cyanophage Infections

Directory of Open Access Journals (Sweden)

Kai Cheng

2017-06-01

Full Text Available Elevated pCO2 and warming are generally expected to influence cyanobacterial growth, and may promote the formation of blooms. Yet, both climate change factors may also influence cyanobacterial mortality by favoring pathogens, such as viruses, which will depend on the ability of the host to adapt. To test this hypothesis, we grew Plectonema boryanum IU597 under two temperature (25 and 29°C and two pCO2 (400 and 800 μatm conditions for 1 year, after which all treatments were re-exposed to control conditions for a period of 3 weeks. At several time points during the 1 year period, and upon re-exposure, we measured various infection characteristics of it associated cyanophage PP, including the burst size, latent period, lytic cycle and the efficiency of plaquing (EOP. As expected, elevated pCO2 promoted growth of P. boryanum equally over the 1 year period, but warming did not. Burst size increased in the warm treatment, but decreased in both the elevated pCO2 and combined treatment. The latent period and lytic cycle both became shorter in the elevated pCO2 and higher temperature treatment, and were further reduced by the combined effect of both factors. Efficiency of plaquing (EOP decreased in the elevated pCO2 treatment, increased in the warm treatment, and increased even stronger in the combined treatment. These findings indicate that elevated pCO2 enhanced the effect of warming, thereby further promoting the virus infection rate. The re-exposure experiments demonstrate adaptation of the host leading to higher biomass build-up with elevated pCO2 over the experimental period, and lower performance upon re-exposure to control conditions. Similarly, virus burst size and EOP increased when given warm adapted host, but were lower as compared to the control when the host was re-exposed to control conditions. Our results demonstrate that adaptation but particularly physiological acclimation to climate change conditions favored viral infections, while

Tree and forest water use under elevated CO2 and temperature in Scandinavian boreal forest

Science.gov (United States)

Berg Hasper, Thomas; Wallin, Göran; Lamba, Shubhangi; Sigurdsson, Bjarni D.; Laudon, Hjalmar; Medhurst, Jane L.; Räntfors, Mats; Linder, Sune; Uddling, Johan

2014-05-01

predictions of boreal atmosphere-biosphere interactions, indicating that tree responses to precipitation and temperature are more important than responses to elevated [CO2] in determining the future forest water-use and hydrology of Scandinavian boreal ecosystems.

Inter-genotypic differences in drought tolerance of maritime pine are modified by elevated [CO2].

Science.gov (United States)

Sánchez-Gómez, David; Mancha, José A; Cervera, M Teresa; Aranda, Ismael

2017-10-17

Despite the importance of growth [CO 2 ] and water availability for tree growth and survival, little information is available on how the interplay of these two factors can shape intraspecific patterns of functional variation in tree species, particularly for conifers. The main objective of the study was to test whether the range of realized drought tolerance within the species can be affected by elevated [CO 2 ]. Intraspecific variability in leaf gas exchange, growth rate and other leaf functional traits were studied in clones of maritime pine. A factorial experiment including water availability, growth [CO 2 ] and four different genotypes was conducted in growth rooms. A 'water deficit' treatment was imposed by applying a cycle of progressive soil water depletion and recovery at two levels of growth [CO 2 ]: 'ambient [CO 2 ]' (aCO 2 400 μmol mol -1 ) and 'elevated [CO 2 ]' (eCO 2 800 μmol mol -1 ). eCO2 had a neutral effect on the impact of drought on growth and leaf gas exchange of the most drought-sensitive genotypes while it aggravated the impact of drought on the most drought-tolerant genotypes at aCO2. Thus, eCO2 attenuated genotypic differences in drought tolerance as compared with those observed at aCO2. Genotypic variation at both levels of growth [CO2] was found in specific leaf area and leaf nitrogen content but not in other physiological leaf traits such as intrinsic water use efficiency and leaf osmotic potential. eCO2 increased Δ 13 C but had no significant effect on δ 18 O. This effect did not interact with the impact of drought, which increased δ 18 O and decreased Δ 13 C. Nevertheless, correlations between Δ 13 C and δ 18 O indicated the non-stomatal component of water use efficiency in this species can be particularly sensitive to drought. Evidence from this study suggests elevated [CO 2 ] can modify current ranges of drought tolerance within tree species. © The Author 2017. Published by Oxford University Press on behalf of the Annals

Influence of Common Bean (Phaseolus vulgaris) Grown in Elevated CO2 on Apatite Dissolution

Science.gov (United States)

Olsen, A. A.; Morra, B.

2016-12-01

We ran a series of experiments to test the hypothesis that release of plant nutrients contained in apatite will be accelerated by the growth of Langstrath Stringless green bean in the presence of atmospheric CO2 meant to simulate possible future atmospheric conditions due a higher demand of nutrients and growth rate caused by elevated CO2. We hypothesize that elevated atmospheric CO2 will lead to both increased root growth and organic acid exudation. These two traits will lead to improved acquisition of P derived from apatite. Experiments were designed to investigate the effect of these changes on soil mineral weathering using plants grown under two conditions, ambient CO2 (400ppm) and elevated CO2 (1000ppm). Plants were grown in flow-through microcosms consisting of a mixture of quartz and apatite sands. Mini-greenhouses were utilized to control CO2 levels. Plant growth was sustained by a nutrient solution lacking in Ca and P. Calcium and P content of the leachate and plant tissue served as a proxy for apatite dissolution. Plants were harvested biweekly during the eight-week experiment and analyzed for Ca and P to calculate apatite dissolution kinetics. Preliminary results suggest that approximately four times more P and Ca are present in the leachate from experiments containing plants under both ambient and elevated CO2 levels than in abiotic experiments; however, the amounts of both P and Ca released in experiments conducted under both ambient and elevated CO2 levels are similar. Additionally, the amount of P in plant tissue grown under ambient and elevated CO2 conditions is similar. Plants grown in elevated CO2 had a greater root to shoot ratio. The planted microcosms were found to have a lower pH than abiotic controls most likely due to root respiration and exudation of organic acids.

Combination treatment of elevated UVB radiation, CO2 and temperature has little effect on silver birch (Betula pendula) growth and phytochemistry.

Science.gov (United States)

Lavola, Anu; Nybakken, Line; Rousi, Matti; Pusenius, Jyrki; Petrelius, Mari; Kellomäki, Seppo; Julkunen-Tiitto, Riitta

2013-12-01

Elevations of carbon dioxide, temperature and ultraviolet-B (UBV) radiation in the growth environment may have a high impact on the accumulation of carbon in plants, and the different factors may work in opposite directions or induce additive effects. To detect the changes in the growth and phytochemistry of silver birch (Betula pendula) seedlings, six genotypes were exposed to combinations of ambient or elevated levels of CO2 , temperature and UVB radiation in top-closed chambers for 7 weeks. The genotypes were relatively similar in their responses, and no significant interactive effects of three-level climate factors on the measured parameters were observed. Elevated UVB had no effect on growth, nor did it alter plant responses to CO2 and/or temperature in combined treatments. Growth in all plant parts increased under elevated CO2 , and height and stem biomass increased under elevated temperature. Increased carbon distribution to biomass did not reduce its allocation to phytochemicals: condensed tannins, most flavonols and phenolic acids accumulated under elevated CO2 and elevated UVB, but this effect disappeared under elevated temperature. Leaf nitrogen content decreased under elevated CO2 . We conclude that, as a result of high genetic variability in phytochemicals, B. pendula seedlings have potential to adapt to the tested environmental changes. The induction in protective flavonoids under UVB radiation together with the positive impact of elevated CO2 and temperature mitigates possible UVB stress effects, and thus atmospheric CO2 concentration and temperature are the climate change factors that will dictate the establishment and success of birch at higher altitudes in the future. © 2013 Scandinavian Plant Physiology Society.

Elevated CO2 as a driver of global dryland greening

KAUST Repository

Lu, Xuefei

2016-02-12

While recent findings based on satellite records indicate a positive trend in vegetation greenness over global drylands, the reasons remain elusive. We hypothesize that enhanced levels of atmospheric CO2 play an important role in the observed greening through the CO2 effect on plant water savings and consequent available soil water increases. Meta-analytic techniques were used to compare soil water content under ambient and elevated CO2 treatments across a range of climate regimes, vegetation types, soil textures and land management practices. Based on 1705 field measurements from 21 distinct sites, a consistent and statistically significant increase in the availability of soil water (11%) was observed under elevated CO2 treatments in both drylands and non-drylands, with a statistically stronger response over drylands (17% vs. 9%). Given the inherent water limitation in drylands, it is suggested that the additional soil water availability is a likely driver of observed increases in vegetation greenness.

Elevated CO2 as a driver of global dryland greening

KAUST Repository

Lu, Xuefei; Wang, Lixin; McCabe, Matthew

2016-01-01

While recent findings based on satellite records indicate a positive trend in vegetation greenness over global drylands, the reasons remain elusive. We hypothesize that enhanced levels of atmospheric CO2 play an important role in the observed greening through the CO2 effect on plant water savings and consequent available soil water increases. Meta-analytic techniques were used to compare soil water content under ambient and elevated CO2 treatments across a range of climate regimes, vegetation types, soil textures and land management practices. Based on 1705 field measurements from 21 distinct sites, a consistent and statistically significant increase in the availability of soil water (11%) was observed under elevated CO2 treatments in both drylands and non-drylands, with a statistically stronger response over drylands (17% vs. 9%). Given the inherent water limitation in drylands, it is suggested that the additional soil water availability is a likely driver of observed increases in vegetation greenness.

Growth strategy of Norway spruce under air elevated [CO2

Science.gov (United States)

Pokorny, R.; Urban, O.; Holisova, P.; Sprtova, M.; Sigut, L.; Slipkova, R.

2012-04-01

Plants will respond to globally increasing atmospheric CO2 concentration ([CO2]) by acclimation or adaptation at physiological and morphological levels. Considering the temporal onset, physiological responses may be categorized as short-term and morphological ones as long-term responses. The degree of plant growth responses, including cell division and cell expansion, is highly variable. It depends mainly on the specie's genetic predisposition, environment, mineral nutrition status, duration of CO2 enrichment, and/or synergetic effects of other stresses. Elevated [CO2] causes changes in tissue anatomy, quantity, size, shape and spatial orientation and can result in altered sink strength. Since, there are many experimental facilities for the investigation of elevated [CO2] effects on trees: i) closed systems or open top chambers (OTCs), ii) semi-open systems (for example glass domes with adjustable lamella windows - DAWs), and iii) free-air [CO2] enrichments (FACE); the results are still unsatisfactory due to: i) relatively short-term duration of experiments, ii) cultivation of young plants with different growth strategy comparing to old ones, iii) plant cultivation under artificial soil and weather conditions, and iv) in non-representative stand structure. In this contribution we are discussing the physiological and morphological responses of Norway spruce trees cultivated in DAWs during eight consecutive growing seasons in the context with other results from Norway spruce cultivation under air-elevated [CO2] conditions. On the level of physiological responses, we discuss the changes in the rate of CO2 assimilation, assimilation capacity, photorespiration, dark respiration, stomatal conductance, water potential and transpiration, and the sensitivity of these physiological processes to temperature. On the level of morphological responses, we discuss the changes in bud and growth phenology, needle and shoot morphology, architecture of crown and root system, wood

Organic matter composition and substrate diversity under elevated CO2 in the Mojave Desert

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Tfaily, M. M.; Hess, N. J.; Koyama, A.; Evans, R. D.

2016-12-01

Little is known about how rising atmospheric CO2 concentration will impact long-term plant biomass or the dynamics of soil organic matter (SOM) in arid ecosystems. In this study, we investigated the change in the molecular composition of SOM by high resolution mass spectrometry after 10 years exposure to elevated atmospheric CO2 concentrations at the Nevada Desert FACE Facility. Samples were collected from soil profiles from 0 to 1m in 0.2m increments under the dominant evergreen shrub (Larrea tridentata). The differences in the composition of SOM were more evident in soils close to the surface and consistent with higher bulk soil organic carbon (C) and total nitrogen (N) concentrations under elevated than ambient CO2, reflecting increased net productivity of shrubs under elevated CO2, which could be attributed to increased litter input from above-ground biomass and/or shallow roots, root exudation and/or microbial residues. This was further supported by the significant increase in the abundance of amino sugars-, protein- and carbohydrate-like compounds. These compounds are involved in diverse pathways ranging from sugars and amino-acid metabolism to lipid biosynthesis. This indicates increased activity and metabolism under elevated CO2 and suggests that elevated CO2 have altered microbial C use patterns, reflecting changes in the quality and quantity of soil C inputs. A significant increase in the mineral-bound soil organic C was also observed in the surface soils under elevated CO2. This was accompanied by increased microbial residues as identified by mass spectrometry that supports microbial lipid analysis, and reflecting accelerated microbial turnover under elevated CO2. Fungal neutral lipid fatty acids (NLFA) abundance doubled under elevated CO2. When provided with excess labile compounds, such as root exudates, and with limited supply of nutrients, fungi assimilate the excess labile C and store it as NLFA likely contributing to increased total N

Growth and control of invasive weeds under elevated CO2

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Atmospheric concentrations of CO2 have been increasing since the onset of the industrial revolution. Regardless of the debate on the effects of this rise on climate, most plants exhibit a positive growth response to elevated CO2 due to increased photosynthesis, resource use efficiency, and/or alloca...

Species Interactions Drive Fish Biodiversity Loss in a High-CO2 World.

Science.gov (United States)

Nagelkerken, Ivan; Goldenberg, Silvan U; Ferreira, Camilo M; Russell, Bayden D; Connell, Sean D

2017-07-24

Accelerating climate change is eroding the functioning and stability of ecosystems by weakening the interactions among species that stabilize biological communities against change [1]. A key challenge to forecasting the future of ecosystems centers on how to extrapolate results from short-term, single-species studies to community-level responses that are mediated by key mechanisms such as competition, resource availability (bottom-up control), and predation (top-down control) [2]. We used CO 2 vents as potential analogs of ocean acidification combined with in situ experiments to test current predictions of fish biodiversity loss and community change due to elevated CO 2 [3] and to elucidate the potential mechanisms that drive such change. We show that high risk-taking behavior and competitive strength, combined with resource enrichment and collapse of predator populations, fostered already common species, enabling them to double their populations under acidified conditions. However, the release of these competitive dominants from predator control led to suppression of less common and subordinate competitors that did not benefit from resource enrichment and reduced predation. As a result, local biodiversity was lost and novel fish community compositions were created under elevated CO 2 . Our study identifies the species interactions most affected by ocean acidification, revealing potential sources of natural selection. We also reveal how diminished predator abundances can have cascading effects on local species diversity, mediated by complex species interactions. Reduced overfishing of predators could therefore act as a key action to stall diversity loss and ecosystem change in a high-CO 2 world. VIDEO ABSTRACT. Copyright © 2017 Elsevier Ltd. All rights reserved.

Soil Microbial Responses to Elevated CO2 and O3 in a Nitrogen-Aggrading Agroecosystem

Science.gov (United States)

Cheng, Lei; Booker, Fitzgerald L.; Burkey, Kent O.; Tu, Cong; Shew, H. David; Rufty, Thomas W.; Fiscus, Edwin L.; Deforest, Jared L.; Hu, Shuijin

2011-01-01

Climate change factors such as elevated atmospheric carbon dioxide (CO2) and ozone (O3) can exert significant impacts on soil microbes and the ecosystem level processes they mediate. However, the underlying mechanisms by which soil microbes respond to these environmental changes remain poorly understood. The prevailing hypothesis, which states that CO2- or O3-induced changes in carbon (C) availability dominate microbial responses, is primarily based on results from nitrogen (N)-limiting forests and grasslands. It remains largely unexplored how soil microbes respond to elevated CO2 and O3 in N-rich or N-aggrading systems, which severely hinders our ability to predict the long-term soil C dynamics in agroecosystems. Using a long-term field study conducted in a no-till wheat-soybean rotation system with open-top chambers, we showed that elevated CO2 but not O3 had a potent influence on soil microbes. Elevated CO2 (1.5×ambient) significantly increased, while O3 (1.4×ambient) reduced, aboveground (and presumably belowground) plant residue C and N inputs to soil. However, only elevated CO2 significantly affected soil microbial biomass, activities (namely heterotrophic respiration) and community composition. The enhancement of microbial biomass and activities by elevated CO2 largely occurred in the third and fourth years of the experiment and coincided with increased soil N availability, likely due to CO2-stimulation of symbiotic N2 fixation in soybean. Fungal biomass and the fungi∶bacteria ratio decreased under both ambient and elevated CO2 by the third year and also coincided with increased soil N availability; but they were significantly higher under elevated than ambient CO2. These results suggest that more attention should be directed towards assessing the impact of N availability on microbial activities and decomposition in projections of soil organic C balance in N-rich systems under future CO2 scenarios. PMID:21731722

Where temperate meets tropical: Multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh community

Science.gov (United States)

McKee, K.L.; Rooth, J.E.

2008-01-01

Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2- and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

Down-regulation of tissue N:P ratios in terrestrial plants by elevated CO2.

Science.gov (United States)

Deng, Qi; Hui, Dafeng; Luo, Yiqi; Elser, James; Wang, Ying-ping; Loladze, Irakli; Zhang, Quanfa; Dennis, Sam

2015-12-01

Increasing atmospheric CO2 concentrations generally alter element stoichiometry in plants. However, a comprehensive evaluation of the elevated CO2 impact on plant nitrogen: phosphorus (N:P) ratios and the underlying mechanism has not been conducted. We synthesized the results from 112 previously published studies using meta-analysis to evaluate the effects of elevated CO2 on the N:P ratio of terrestrial plants and to explore the underlying mechanism based on plant growth and soil P dynamics. Our results show that terrestrial plants grown under elevated CO2 had lower N:P ratios in both above- and belowground biomass across different ecosystem types. The response ratio for plant N:P was negatively correlated with the response ratio for plant growth in croplands and grasslands, and showed a stronger relationship for P than for N. In addition, the CO2-induced down-regulation of plant N:P was accompanied by 19.3% and 4.2% increases in soil phosphatase activity and labile P, respectively, and a 10.1% decrease in total soil P. Our results show that down-regulation of plant N:P under elevated CO2 corresponds with accelerated soil P cycling. These findings should be useful for better understanding of terrestrial plant stoichiometry in response to elevated CO2 and of the underlying mechanisms affecting nutrient dynamics under climate change.

Calcification by juvenile corals under heterotrophy and elevated CO2

Science.gov (United States)

Drenkard, E. J.; Cohen, A. L.; McCorkle, D. C.; de Putron, S. J.; Starczak, V. R.; Zicht, A. E.

2013-09-01

Ocean acidification (OA) threatens the existence of coral reefs by slowing the rate of calcium carbonate (CaCO3) production of framework-building corals thus reducing the amount of CaCO3 the reef can produce to counteract natural dissolution. Some evidence exists to suggest that elevated levels of dissolved inorganic nutrients can reduce the impact of OA on coral calcification. Here, we investigated the potential for enhanced energetic status of juvenile corals, achieved via heterotrophic feeding, to modulate the negative impact of OA on calcification. Larvae of the common Atlantic golf ball coral, Favia fragum, were collected and reared for 3 weeks under ambient (421 μatm) or significantly elevated (1,311 μatm) CO2 conditions. The metamorphosed, zooxanthellate spat were either fed brine shrimp (i.e., received nutrition from photosynthesis plus heterotrophy) or not fed (i.e., primarily autotrophic). Regardless of CO2 condition, the skeletons of fed corals exhibited accelerated development of septal cycles and were larger than those of unfed corals. At each CO2 level, fed corals accreted more CaCO3 than unfed corals, and fed corals reared under 1,311 μatm CO2 accreted as much CaCO3 as unfed corals reared under ambient CO2. However, feeding did not alter the sensitivity of calcification to increased CO2; ∆ calcification/∆Ω was comparable for fed and unfed corals. Our results suggest that calcification rates of nutritionally replete juvenile corals will decline as OA intensifies over the course of this century. Critically, however, such corals could maintain higher rates of skeletal growth and CaCO3 production under OA than those in nutritionally limited environments.

Mineral nutrition and plant responses to elevated levels of atmospheric CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Ahluwalia, A.

1996-08-01

The atmospheric concentration of CO{sub 2}, a radiatively-active ({open_quotes}green-house{close_quotes}) gas, is increasing. This increase is considered a post-industrial phenomenon attributable to increasing rates of fossil fuel combustion and changing land use practices, particularly deforestation. Climate changes resulting from such elevated atmospheric CO{sub 2} levels, in addition to the direct effects of increased CO{sub 2}, are expected to modify the productivity of forests and alter species distributions. Elevated levels of CO{sub 2} have been shown, in some cases, to lead to enhanced growth rates in plants, particularly those with C{sub 3} metabolism - indicating that plant growth is CO{sub 2}-limited in these situations. Since the major process underlying growth is CO{sub 2} assimilation via photosynthesis in leaves, plant growth represents a potential for sequestering atmospheric carbon into biomass, but this potential could be hampered by plant carbon sink size. Carbon sinks are utilization sites for assimilated carbon, enabling carbon assimilation to proceed without potential inhibition from the accumulation of assimilate (photosynthate). Plant growth provides new sinks for assimilated carbon which permits greater uptake of atmospheric carbon dioxide. However, sinks are, on the whole, reduced in size by stress events due to the adverse effects of stress on photosynthetic rates and therefore growth. This document reviews some of the literature on plant responses to increasing levels of atmospheric carbon dioxide and to inadequate nutrient supply rates, and with this background, the potential for nutrient-limited plants to respond to increasing carbon dioxide is addressed. Conclusions from the literature review are then tested experimentally by means of a case study exploring carbon-nitrogen interactions in seedlings of loblolly pine.

Changes in the microbial community structure of bacteria, archaea and fungi in response to elevated CO(2) and warming in an Australian native grassland soil.

Science.gov (United States)

Hayden, Helen L; Mele, Pauline M; Bougoure, Damian S; Allan, Claire Y; Norng, Sorn; Piceno, Yvette M; Brodie, Eoin L; Desantis, Todd Z; Andersen, Gary L; Williams, Amity L; Hovenden, Mark J

2012-12-01

The microbial community structure of bacteria, archaea and fungi is described in an Australian native grassland soil after more than 5 years exposure to different atmospheric CO2 concentrations ([CO2]) (ambient, +550 ppm) and temperatures (ambient, + 2°C) under different plant functional types (C3 and C4 grasses) and at two soil depths (0-5 cm and 5-10 cm). Archaeal community diversity was influenced by elevated [CO2], while under warming archaeal 16S rRNA gene copy numbers increased for C4 plant Themeda triandra and decreased for the C3 plant community (P fungi in soil responded differently to elevated [CO2], warming and their interaction. Taxa identified as significantly climate-responsive could show differing trends in the direction of response ('+' or '-') under elevated CO2 or warming, which could then not be used to predict their interactive effects supporting the need to investigate interactive effects for climate change. The approach of focusing on specific taxonomic groups provides greater potential for understanding complex microbial community changes in ecosystems under climate change. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Distinct responses of soil microbial communities to elevated CO2 and O3 in a soybean agro-ecosystem.

Science.gov (United States)

He, Zhili; Xiong, Jinbo; Kent, Angela D; Deng, Ye; Xue, Kai; Wang, Gejiao; Wu, Liyou; Van Nostrand, Joy D; Zhou, Jizhong

2014-03-01

The concentrations of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) have been rising due to human activities. However, little is known about how such increases influence soil microbial communities. We hypothesized that elevated CO2 (eCO2) and elevated O3 (eO3) would significantly affect the functional composition, structure and metabolic potential of soil microbial communities, and that various functional groups would respond to such atmospheric changes differentially. To test these hypotheses, we analyzed 96 soil samples from a soybean free-air CO2 enrichment (SoyFACE) experimental site using a comprehensive functional gene microarray (GeoChip 3.0). The results showed the overall functional composition and structure of soil microbial communities shifted under eCO2, eO3 or eCO2+eO3. Key functional genes involved in carbon fixation and degradation, nitrogen fixation, denitrification and methane metabolism were stimulated under eCO2, whereas those involved in N fixation, denitrification and N mineralization were suppressed under eO3, resulting in the fact that the abundance of some eO3-supressed genes was promoted to ambient, or eCO2-induced levels by the interaction of eCO2+eO3. Such effects appeared distinct for each treatment and significantly correlated with soil properties and soybean yield. Overall, our analysis suggests possible mechanisms of microbial responses to global atmospheric change factors through the stimulation of C and N cycling by eCO2, the inhibition of N functional processes by eO3 and the interaction by eCO2 and eO3. This study provides new insights into our understanding of microbial functional processes in response to global atmospheric change in soybean agro-ecosystems.

Impacts of Elevated Atmospheric CO2 and O3 on Paper Birch (Betula papyrifera: Reproductive Fitness

Directory of Open Access Journals (Sweden)

Joseph N. T. Darbah

2007-01-01

Full Text Available Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO3 and O3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment site in Rhinelander, WI. Elevated CO2 increased both male and female flower production, while elevated O3 increased female flower production compared to trees in control rings. Interestingly, very little flowering has yet occurred in combined treatment. Elevated CO2 had significant positive effect on birch catkin size, weight, and germination success rate (elevated CO2 increased germination rate of birch by 110% compared to ambient CO2 concentrations, decreased seedling mortality by 73%, increased seed weight by 17%, increased root length by 59%, and root-to-shoot ratio was significantly decreased, all at 3 weeks after germination, while the opposite was true of elevated O3 (elevated O3 decreased the germination rate of birch by 62%, decreased seed weight by 25%, and increased root length by 15%. Under elevated CO2, plant dry mass increased by 9 and 78% at the end of 3 and 14 weeks, respectively. Also, the root and shoot lengths, as well as the biomass of the seedlings, were increased for seeds produced under elevated CO2, while the reverse was true for seedlings from seeds produced under the elevated O3. Similar trends in treatment differences were observed in seed characteristics, germination, and seedling development for seeds collected in both 2004 and 2005. Our results suggest that elevated CO2 and O3 can dramatically affect flowering, seed production, and seed quality of paper birch, affecting reproductive fitness of this species.

Effect of elevated CO2 on chlorpyriphos degradation and soil microbial activities in tropical rice soil.

Science.gov (United States)

Adak, Totan; Munda, Sushmita; Kumar, Upendra; Berliner, J; Pokhare, Somnath S; Jambhulkar, N N; Jena, M

2016-02-01

Impact of elevated CO2 on chlorpyriphos degradation, microbial biomass carbon, and enzymatic activities in rice soil was investigated. Rice (variety Naveen, Indica type) was grown under four conditions, namely, chambered control, elevated CO2 (550 ppm), elevated CO2 (700 ppm) in open-top chambers and open field. Chlorpyriphos was sprayed at 500 g a.i. ha(-1) at maximum tillering stage. Chlorpyriphos degraded rapidly from rice soils, and 88.4% of initially applied chlorpyriphos was lost from the rice soil maintained under elevated CO2 (700 ppm) by day 5 of spray, whereas the loss was 80.7% from open field rice soil. Half-life values of chlorpyriphos under different conditions ranged from 2.4 to 1.7 days with minimum half-life recorded with two elevated CO2 treatments. Increased CO2 concentration led to increase in temperature (1.2 to 1.8 °C) that played a critical role in chlorpyriphos persistence. Microbial biomass carbon and soil enzymatic activities specifically, dehydrogenase, fluorescien diacetate hydrolase, urease, acid phosphatase, and alkaline phosphatase responded positively to elevated CO2 concentrations. Generally, the enzyme activities were highly correlated with each other. Irrespective of the level of CO2, short-term negative influence of chlorpyriphos was observed on soil enzymes till day 7 of spray. Knowledge obtained from this study highlights that the elevated CO2 may negatively influence persistence of pesticide but will have positive effects on soil enzyme activities.

The effects of prolonged exposure to elevated temperatures and elevated CO2 levels on the growth, yield and dry matter partitioning of field-sown meadow fescue

Directory of Open Access Journals (Sweden)

Kaija Hakala

1996-05-01

Full Text Available Field-sown meadow fescue (Festuca pratensis, cv. Kalevi stands were exposed to elevated temperatures (+3°C and elevated CO2, (700 ppm levels in two experiments conducted in 1992-1993 (experiment 1 and in 1994-1995 (experiment 2. Total aboveground yield was, on average, 38% higher at elevated than at ambient temperatures. At ambient temperatures elevated CO2 increased the number of tillers by 63% in 1992, 24% in 1993, 90% in 1994 and 14% in 1995. At elevated temperatures, the increase in tiller number in elevated CO2 was seen only in the first growing seasons after sowing. The total yield in a growing season was about 10% higher in elevated CO2 in experiment 1. In experiment 2 the yield was more than 20% higher in elevated CO2 at elevated temperatures, whereas at ambient temperatures the rise in CO2 level had no effect on the yield; the root biomass, however, increased by more than 30%. In elevated CO2 at ambient temperatures the root biomass also increased in experiment I, but at elevated temperatures there was no consistent change. The soluble carbohydrate content of above-ground biomass was 5-48% higher in elevated CO2 at most of the measuring times during the growing season, but the nitrogen content did not show a clear decrease. The reasons for the lack of a marked increase in biomass in elevated CO2 despite a 40-60% increase in photosynthesis are discussed.

Influence of elevated CO2 on canopy development and red:far-red ratios in two-storied stands of Ricinus communis

International Nuclear Information System (INIS)

Arnone, J.A.; Körner, C.

1993-01-01

Vertical structure of plant stands and canopies may change under conditions of elevated CO2 due to differential responses of overstory and understory plants or plant parts. In the long term, seedling recruitment, competition, and thus population or community structure may be affected. Aside from the possible differential direct effects of elevated CO2 on photosynthesis and growth, both the quantity and quality of the light below the overstory canopy could be indirectly affected by CO2-induced changes in overstory leaf area index (LAI) and/or changes in overstory leaf quality. In order to explore such possible interactions, we compared canopy leaf area development, canopy light extinction and the quality of light beneath overstory leaves of two-storied monospecific stands of Ricinus communis exposed to ambient (340 micro litre per litre) and elevated (610 micro litre per litre) CO2. Plants in each stand were grown in a common soil as closed ''artificial ecosystems'' with a ground area of 6.7 square metre. LAI of overstory plants in all ecosystems more than doubled during the experiment but was not different between CO2 treatments at the end. As a consequence, extinction of photosynthetically active radiation (PAR) was also not altered. However, under elevated CO2 the red to far-red ratio (R:FR) measured beneath overstory leaves was 10% lower than in ecosystems treated with ambient CO2. This reduction was associated with increased thickness of palisade layers of overstory leaves and appears to be a plausible explanation for the specific enhancement of stem elongation of understory plants (without a corresponding biomass response) under elevated CO2

Chemical and anatomical changes in Liquidambar styraciflua L. xylem after long term exposure to elevated CO2

International Nuclear Information System (INIS)

Kim, Keonhee; Labbé, Nicole; Warren, Jeffrey M.; Elder, Thomas; Rials, Timothy G.

2015-01-01

The anatomical and chemical characteristics of sweetgum were studied after 11 years of elevated CO 2 (544 ppm, ambient at 391 ppm) exposure. Anatomically, branch xylem cells were larger for elevated CO 2 trees, and the cell wall thickness was thinner. Chemically, elevated CO 2 exposure did not impact the structural components of the stem wood, but non-structural components were significantly affected. Principal component analysis (PCA) was employed to detect differences between the CO 2 treatments by considering numerous structural and chemical variables, as well as tree size, and data from previously published sources (i.e., root biomass, production and turnover). The PCA results indicated a clear separation between trees exposed to ambient and elevated CO 2 conditions. Correlation loadings plots of the PCA revealed that stem structural components, ash, Ca, Mg, total phenolics, root biomass, production and turnover were the major responses that contribute to the separation between the elevated and ambient CO 2 treated trees. - Highlights: • First study of wood properties after 11 years of higher level of CO 2 treatment. • Elevated CO 2 exposure does not impact structural components of wood. • Total phenolics content and some inorganics were significantly affected. • Branch xylem cells were larger under elevated CO 2 . • Cell wall thickness was thinner under elevated CO 2 . - Elevated CO 2 in atmosphere did not impact the structural components yet altered some of non-structural components and anatomical properties after 11 years of exposure on sweetgum

SEASONAL PATTERNS OF PHOTOSYNTHESIS IN DOUGLAS FIR SEEDLINGS DURING THE THIRD AND FOURTH YEAR OF EXPOSURE TO ELEVATED CO2 AND TEMPERATURE

Science.gov (United States)

We examined the interactive effects of elevated atmospheric CO2 and temperature on seasonal patterns of photosynthesis in Douglas-fir (Psuedotsuga menziesii (Mirb.) Franco) seedlings. Seedlings were grown in sunlit chambers controlled to track either ambient (~400 ppm) CO2 or am...

Effect of elevated CO2 on degradation of azoxystrobin and soil microbial activity in rice soil.

Science.gov (United States)

Manna, Suman; Singh, Neera; Singh, V P

2013-04-01

An experiment was conducted in open-top chambers (OTC) to study the effect of elevated CO2 (580 ± 20 μmol mol(-1)) on azoxystrobin degradation and soil microbial activities. Results indicated that elevated CO2 did not have any significant effect on the persistence of azoxystrobin in rice-planted soil. The half-life values for the azoxystrobin in rice soils were 20.3 days in control (rice grown at ambient CO2 outdoors), 19.3 days in rice grown under ambient CO2 atmosphere in OTC, and 17.5 days in rice grown under elevated CO2 atmosphere in OTC. Azoxystrobin acid was recovered as the only metabolite of azoxystrobin, but it did not accumulate in the soil/water and was further metabolized. Elevated CO2 enhanced soil microbial biomass (MBC) and alkaline phosphatase activity of soil. Compared with rice grown at ambient CO2 (both outdoors and in OTC), the soil MBC at elevated CO2 increased by twofold. Elevated CO2 did not affect dehydrogenase, fluorescein diacetate, and acid phosphatase activity. Azoxystrobin application to soils, both ambient and elevated CO2, inhibited alkaline phosphates activity, while no effect was observed on other enzymes. Slight increase (1.8-2 °C) in temperature inside OTC did not affect microbial parameters, as similar activities were recorded in rice grown outdoors and in OTC at ambient CO2. Higher MBC in soil at elevated CO2 could be attributed to increased carbon availability in the rhizosphere via plant metabolism and root secretion; however, it did not significantly increase azoxystrobin degradation, suggesting that pesticide degradation was not the result of soil MBC alone. Study suggested that increased CO2 levels following global warming might not adversely affect azoxystrobin degradation. However, global warming is a continuous and cumulative process, therefore, long-term studies are necessary to get more realistic assessment of global warming on fate of pesticide.

Greater antioxidant and respiratory metabolism in field-grown soybean exposed to elevated O3 under both ambient and elevated CO2.

Science.gov (United States)

Gillespie, Kelly M; Xu, Fangxiu; Richter, Katherine T; McGrath, Justin M; Markelz, R J Cody; Ort, Donald R; Leakey, Andrew D B; Ainsworth, Elizabeth A

2012-01-01

Antioxidant metabolism is responsive to environmental conditions, and is proposed to be a key component of ozone (O(3)) tolerance in plants. Tropospheric O(3) concentration ([O(3)]) has doubled since the Industrial Revolution and will increase further if precursor emissions rise as expected over this century. Additionally, atmospheric CO(2) concentration ([CO(2)]) is increasing at an unprecedented rate and will surpass 550 ppm by 2050. This study investigated the molecular, biochemical and physiological changes in soybean exposed to elevated [O(3) ] in a background of ambient [CO(2)] and elevated [CO(2)] in the field. Previously, it has been difficult to demonstrate any link between antioxidant defences and O(3) stress under field conditions. However, this study used principle components analysis to separate variability in [O(3)] from variability in other environmental conditions (temperature, light and relative humidity). Subsequent analysis of covariance determined that soybean antioxidant metabolism increased with increasing [O(3)], in both ambient and elevated [CO(2)]. The transcriptional response was dampened at elevated [CO(2)], consistent with lower stomatal conductance and lower O(3) flux into leaves. Energetically expensive increases in antioxidant metabolism and tetrapyrrole synthesis at elevated [O(3)] were associated with greater transcript levels of enzymes involved in respiratory metabolism. © 2011 Blackwell Publishing Ltd.

A multi-biome gap in understanding of crop and ecosystem responses to elevated CO2.

Science.gov (United States)

Leakey, Andrew D B; Bishop, Kristen A; Ainsworth, Elizabeth A

2012-06-01

A key finding from elevated [CO(2)] field experiments is that the impact of elevated [CO(2)] on plant and ecosystem function is highly dependent upon other environmental conditions, namely temperature and the availability of nutrients and soil moisture. In addition, there is significant variation in the response to elevated [CO(2)] among plant functional types, species and crop varieties. However, experimental data on plant and ecosystem responses to elevated [CO(2)] are strongly biased to economically and ecologically important systems in the temperate zone. There is a multi-biome gap in experimental data that is most severe in the tropics and subtropics, but also includes high latitudes. Physiological understanding of the environmental conditions and species found at high and low latitudes suggest they may respond differently to elevated [CO(2)] than well-studied temperate systems. Addressing this knowledge gap should be a high priority as it is vital to understanding 21st century food supply and ecosystem feedbacks on climate change. Published by Elsevier Ltd.

Elevated atmospheric CO₂ decreases the ammonia compensation point of barley plants

DEFF Research Database (Denmark)

Wang, Liang; Pedas, Pai; Eriksson, Ulf Dennis

2013-01-01

mu mol mol(-1)) or elevated (800 mu mol mol(-1)) CO2 concentration with NO3- or NH4NO3 as the nitrogen source. The concentrations of NH4+ and H+ in the leaf apoplastic solution were measured along with different foliar N pools and enzymes involved in N metabolism. Elevated CO2 caused a threefold...... decrease in the NH4+ concentration in the apoplastic solution and slightly acidified it. This resulted in a decline of the chi(NH3) from 2.25 and 2.95 nmol mol(-1) under ambient CO2 to 0.37 and 0.89 nmol mol(-1) at elevated CO2 in the NO3- and NH4NO3 treatments, respectively. The decrease in chi(NH3...

Plant growth responses to elevated atmospheric CO₂ are increased by phosphorus sufficiency but not by arbuscular mycorrhizas

DEFF Research Database (Denmark)

Jakobsen, Iver; Smith, Sally E.; Smith, F. Andrew

2016-01-01

Capturing the full growth potential in crops under future elevated CO2 (eCO2) concentrations would be facilitated by improved understanding of eCO2 effects on uptake and use of mineral nutrients. This study investigates interactions of eCO2, soil phosphorus (P), and arbuscular mycorrhizal (AM......) symbiosis in Medicago truncatula and Brachypodium distachyon grown under the same conditions. The focus was on eCO2 effects on vegetative growth, efficiency in acquisition and use of P, and expression of phosphate transporter (PT) genes. Growth responses to eCO2 were positive at P sufficiency, but under low...

No evidence that elevated CO2 gives tropical lianas an advantage over tropical trees.

Science.gov (United States)

Marvin, David C; Winter, Klaus; Burnham, Robyn J; Schnitzer, Stefan A

2015-05-01

Recent studies indicate that lianas are increasing in size and abundance relative to trees in neotropical forests. As a result, forest dynamics and carbon balance may be altered through liana-induced suppression of tree growth and increases in tree mortality. Increasing atmospheric CO2 is hypothesized to be responsible for the increase in neotropical lianas, yet no study has directly compared the relative response of tropical lianas and trees to elevated CO2 . We explicitly tested whether tropical lianas had a larger response to elevated CO2 than co-occurring tropical trees and whether seasonal drought alters the response of either growth form. In two experiments conducted in central Panama, one spanning both wet and dry seasons and one restricted to the dry season, we grew liana (n = 12) and tree (n = 10) species in open-top growth chambers maintained at ambient or twice-ambient CO2 levels. Seedlings of eight individuals (four lianas, four trees) were grown in the ground in each chamber for at least 3 months during each season. We found that both liana and tree seedlings had a significant and positive response to elevated CO2 (in biomass, leaf area, leaf mass per area, and photosynthesis), but that the relative response to elevated CO2 for all variables was not significantly greater for lianas than trees regardless of the season. The lack of differences in the relative response between growth forms does not support the hypothesis that elevated CO2 is responsible for increasing liana size and abundance across the neotropics. © 2014 John Wiley & Sons Ltd.

Elevated CO2 and nitrogen effects on soil CO2 flux from a pasture upon return to cultivation

Science.gov (United States)

Soil CO2 efflux patterns associated with converting pastures back to row crop production remain understudied in the Southeastern U.S. A 10-year study of bahiagrass (Paspalum notatum Flüggé) response to elevated CO2 was conducted using open top field chambers on a Blanton loamy sand (loamy siliceous,...

Which are the most important parameters for modelling carbon assimilation in boreal Norway spruce under elevated [CO(2)] and temperature conditions?

Science.gov (United States)

Hall, Marianne; Medlyn, Belinda E; Abramowitz, Gab; Franklin, Oskar; Räntfors, Mats; Linder, Sune; Wallin, Göran

2013-11-01

Photosynthesis is highly responsive to environmental and physiological variables, including phenology, foliage nitrogen (N) content, atmospheric CO2 concentration ([CO2]), irradiation (Q), air temperature (T) and vapour pressure deficit (D). Each of these responses is likely to be modified by long-term changes in climatic conditions such as rising air temperature and [CO2]. When modelling photosynthesis under climatic changes, which parameters are then most important to calibrate for future conditions? To assess this, we used measurements of shoot carbon assimilation rates and microclimate conditions collected at Flakaliden, northern Sweden. Twelve 40-year-old Norway spruce trees were enclosed in whole-tree chambers and exposed to elevated [CO2] and elevated air temperature, separately and in combination. The treatments imposed were elevated temperature, +2.8 °C in July/August and +5.6 °C in December above ambient, and [CO2] (ambient CO2 ∼370 μ mol mol(-1), elevated CO2 ∼700 μ mol mol(-1)). The relative importance of parameterization of Q, T and D responses for effects on the photosynthetic rate, expressed on a projected needle area, and the annual shoot carbon uptake was quantified using an empirical shoot photosynthesis model, which was developed and fitted to the measurements. The functional form of the response curves was established using an artificial neural network. The [CO2] treatment increased annual shoot carbon (C) uptake by 50%. Most important was effects on the light response curve, with a 67% increase in light-saturated photosynthetic rate, and a 52% increase in the initial slope of the light response curve. An interactive effect of light saturated photosynthetic rate was found with foliage N status, but no interactive effect for high temperature and high CO2. The air temperature treatment increased the annual shoot C uptake by 44%. The most important parameter was the seasonality, with an elongation of the growing season by almost 4

The impact of elevated CO2 and temperature on grain quality of rice grown under open-air field conditions.

Science.gov (United States)

Jing, Liquan; Wang, Juan; Shen, Shibo; Wang, Yunxia; Zhu, Jianguo; Wang, Yulong; Yang, Lianxin

2016-08-01

Rising atmospheric CO2 is accompanied by global warming. However, interactive effects of elevated CO2 and temperature have not been well studied on grain quality of rice. A japonica cultivar was grown in the field using a free-air CO2 enrichment facility in combination with a canopy air temperature increase system in 2014. The gas fumigation (200 µmol mol(-1) above ambient CO2 ) and temperature increase (1 °C above ambient air temperature) were performed from tillering until maturity. Compared with the control (ambient CO2 and air temperature), elevated CO2 increased grain length and width as well as grain chalkiness but decreased protein concentrations. In contrast, the increase in canopy air temperature had less effect on these parameters except for grain chalkiness. The starch pasting properties of rice flour and taste analysis of cooked rice indicated that the palatability of rice was improved by CO2 and/or temperature elevation, with the combination of the two treatments showing the most significant changes compared with ambient rice. It is concluded that projected CO2 in 2050 may have larger effects on rice grain quality than the projected temperature increase. Although deterioration in milling suitability, grain appearance and nutritional quality can be expected, the taste of cooked rice might be better in the future environment. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine.

Science.gov (United States)

Chang, Christine Y; Fréchette, Emmanuelle; Unda, Faride; Mansfield, Shawn D; Ensminger, Ingo

2016-10-01

Rising global temperature and CO 2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO 2 , affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L -1 ) or elevated (800 μmol mol -1 ) CO 2 , and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO 2 (LTAC), elevated temperature/ambient CO 2 (ETAC), or elevated temperature/elevated CO 2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus Our findings suggest that exposure to elevated temperature and CO 2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO 2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low

The growth response of plants to elevated CO2 under non-optimal environmental conditions

NARCIS (Netherlands)

Poorter, H.; Pérez-Soba, M.

2001-01-01

Under benign environmental conditions, plant growth is generally stimulated by elevated atmospheric CO2 concentrations. When environmental conditions become sub- or supra-optimal for growth, changes in the biomass enhancement ratio (BER; total plant biomass at elevated CO2 divided by plant biomass

Responses of Four Rice Varieties to Elevated CO2 and Different Salinity Levels

Directory of Open Access Journals (Sweden)

Sheidollah Kazemi

2018-05-01

Full Text Available Abstract:: This study was carried out in 2014 at Isfahan University of Technology, Iran, to evaluate the responses of four rice varieties (Neda, Deylamani, Shiroudi and Domsorkh to ambient (360 ± 50 μmol/mol and elevated (700 ± 50 μmol/mol air carbon dioxide (CO2 concentrations under four salinity levels (0, 30, 60 and 90 mmol/L NaCl. There was significant variation among rice varieties in response to elevated CO2 concentration under the four salinity levels. Under non-saline condition, elevated CO2 increased the dry weight of Neda, Deylamani and Domsorkh by 8%, 50% and 8%, respectively, but reversely decreased that of Shiroudi by 34%. Increasing CO2 concentration significantly reduced the negative effects of salinity on Shiroudi, but these effects were even increased in Deylamani and Domsorkh under all the salinity levels and in Neda only under 30 and 60 mmol/L NaCl. Significant correlations were established between plant dry weight, SPAD value and leaf area under both CO2 levels. However, this trend was observed only at ambient CO2 concentration in the presence of soluble carbohydrates. The results revealed the genotype and salinity dependence of the effects of CO2 concentrations on the rice traits investigated. Key words: CO2 concentration, genetic diversity, salt tolerance, water soluble carbohydrate

Competitive interactions between native and invasive exotic plant species are altered under elevated carbon dioxide.

Science.gov (United States)

Manea, Anthony; Leishman, Michelle R

2011-03-01

We hypothesized that the greater competitive ability of invasive exotic plants relative to native plants would increase under elevated CO(2) because they typically have traits that confer the ability for fast growth when resources are not limiting and thus are likely to be more responsive to elevated CO(2). A series of competition experiments under ambient and elevated CO(2) glasshouse conditions were conducted to determine an index of relative competition intensity for 14 native-invasive exotic species-pairs. Traits including specific leaf area, leaf mass ratio, leaf area ratio, relative growth rate, net assimilation rate and root weight ratio were measured. Competitive rankings within species-pairs were not affected by CO(2) concentration: invasive exotic species were more competitive in 9 of the 14 species-pairs and native species were more competitive in the remaining 5 species-pairs, regardless of CO(2) concentration. However, there was a significant interaction between plant type and CO(2) treatment due to reduced competitive response of native species under elevated compared with ambient CO(2) conditions. Native species had significantly lower specific leaf area and leaf area ratio under elevated compared with ambient CO(2). We also compared traits of more-competitive with less-competitive species, regardless of plant type, under both CO(2) treatments. More-competitive species had smaller leaf weight ratio and leaf area ratio, and larger relative growth rate and net assimilation rate under both ambient and elevated CO(2) conditions. These results suggest that growth and allocation traits can be useful predictors of the outcome of competitive interactions under both ambient and elevated CO(2) conditions. Under predicted future atmospheric CO(2) conditions, competitive rankings among species may not change substantially, but the relative success of invasive exotic species may be increased. Thus, under future atmospheric CO(2) conditions, the ecological and

Growth under elevated atmospheric CO(2) concentration accelerates leaf senescence in sunflower (Helianthus annuus L.) plants.

Science.gov (United States)

de la Mata, Lourdes; Cabello, Purificación; de la Haba, Purificación; Agüera, Eloísa

2012-09-15

Some morphogenetic and metabolic processes were sensitive to a high atmospheric CO(2) concentration during sunflower primary leaf ontogeny. Young leaves of sunflower plants growing under elevated CO(2) concentration exhibited increased growth, as reflected by the high specific leaf mass referred to as dry weight in young leaves (16 days). The content of photosynthetic pigments decreased with leaf development, especially in plants grown under elevated CO(2) concentrations, suggesting that high CO(2) accelerates chlorophyll degradation, and also possibly leaf senescence. Elevated CO(2) concentration increased the oxidative stress in sunflower plants by increasing H(2)O(2) levels and decreasing activity of antioxidant enzymes such as catalase and ascorbate peroxidase. The loss of plant defenses probably increases the concentration of reactive oxygen species in the chloroplast, decreasing the photosynthetic pigment content as a result. Elevated CO(2) concentration was found to boost photosynthetic CO(2) fixation, especially in young leaves. High CO(2) also increased the starch and soluble sugar contents (glucose and fructose) and the C/N ratio during sunflower primary leaf development. At the beginning of senescence, we observed a strong increase in the hexoses to sucrose ratio that was especially marked at high CO(2) concentration. These results indicate that elevated CO(2) concentration could promote leaf senescence in sunflower plants by affecting the soluble sugar levels, the C/N ratio and the oxidative status during leaf ontogeny. It is likely that systemic signals produced in plants grown with elevated CO(2), lead to early senescence and a higher oxidation state of the cells of these plant leaves. Copyright © 2012 Elsevier GmbH. All rights reserved.

An investigation of the calcification response of the scleractinian coral Astrangia poculata to elevated pCO2 and the effects of nutrients, zooxanthellae and gender

Science.gov (United States)

Holcomb, M.; Cohen, A. L.; McCorkle, D. C.

2012-01-01

The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786) were investigated at two different temperatures (16 °C and 24 °C). Corals exposed to elevated pCO2 tended to have lower relative calcification rates, as estimated from changes in buoyant weights. Experimental nutrient enrichments had no significant effect nor did there appear to be any interaction between pCO2 and nutrients. Elevated pCO2 appeared to have a similar effect on coral calcification whether zooxanthellae were present or absent at 16 °C. However, at 24 °C, the interpretation of the results is complicated by a significant interaction between gender and pCO2 for spawning corals. At 16 °C, gamete release was not observed, and no gender differences in calcification rates were observed - female and male corals showed similar reductions in calcification rates in response to elevated CO2 (15% and 19% respectively). Corals grown at 24 °C spawned repeatedly and male and female corals exhibited two different growth rate patterns - female corals grown at 24 °C and exposed to CO2 had calcification rates 39% lower than females grown at ambient CO2, while males showed a non-significant decline of 5% under elevated CO2. The increased sensitivity of females to elevated pCO2 may reflect a greater investment of energy in reproduction (egg production) relative to males (sperm production). These results suggest that both gender and spawning are important factors in determining the sensitivity of corals to ocean acidification, and considering these factors in future research may be critical to predicting how the population structures of marine calcifiers will change in response to ocean acidification.

Elevated [CO2] magnifies isoprene emissions under heat and improves thermal resistance in hybrid aspen

OpenAIRE

Sun, Zhihong; H?ve, Katja; Vislap, Vivian; Niinemets, ?lo

2013-01-01

Isoprene emissions importantly protect plants from heat stress, but the emissions become inhibited by instantaneous increase of [CO2], and it is currently unclear how isoprene-emitting plants cope with future more frequent and severe heat episodes under high [CO2]. Hybrid aspen (Populus tremula x Populus tremuloides) saplings grown under ambient [CO2] of 380 ?mol mol?1 and elevated [CO2] of 780 ?mol mol?1 were used to test the hypothesis that acclimation to elevated [CO2] reduces the inhibito...

Lignification in beech grown at elevated CO2 concentrations: interaction with nutrient availability and leaf maturation

International Nuclear Information System (INIS)

Blaschke, L; Forstreuter, M.; Sheppard, L. J.; Leith, K.; Murray, M. B.; Polle, A.

2002-01-01

Results of a study undertaken to investigate contradictory observations reported in the literature to the effect that growth in elevated carbon dioxide affects ontogeny, are discussed. Results of this study showed that seedlings grown at elevated carbon dioxide had nitrogen concentrations of about 15 per cent lower than seedlings grown in ambient carbon dioxide. Elevated carbon dioxide caused increased growth and biomass production in trees with a medium to high nutrient supply, but had no effect on growth of trees with a low nutrient supply rate. Because elevated carbon dioxide enhanced seedling growth in the high nutrient supply treatments, the total amount of lignin produced per seedling was higher in these treatments. Overall, the results suggest that carbon dioxide availability does not directly affect lignin concentrations, but affects them indirectly through the effects on or an interaction with nitrogen supply and growth. In seedlings, elevated carbon dioxide reduced lignin concentration on a dry mass basis, indicating diminished wood quality in a carbon dioxide-enriched atmosphere. 51 refs., 2 tabs., 5 figs

Elevated CO2 can modify the response to a water status gradient in a steppe grass: from cell organelles to photosynthetic capacity to plant growth.

Science.gov (United States)

Jiang, Yanling; Xu, Zhenzhu; Zhou, Guangsheng; Liu, Tao

2016-07-12

The atmospheric CO2 concentration is rising continuously, and abnormal precipitation may occur more frequently in the future. Although the effects of elevated CO2 and drought on plants have been well reported individually, little is known about their interaction, particularly over a water status gradient. Here, we aimed to characterize the effects of elevated CO2 and a water status gradient on the growth, photosynthetic capacity, and mesophyll cell ultrastructure of a dominant grass from a degraded grassland. Elevated CO2 stimulated plant biomass to a greater extent under moderate changes in water status than under either extreme drought or over-watering conditions. Photosynthetic capacity and stomatal conductance were also enhanced by elevated CO2 under moderate drought, but inhibited with over-watering. Severe drought distorted mesophyll cell organelles, but CO2 enrichment partly alleviated this effect. Intrinsic water use efficiency (WUEi) and total biomass water use efficiency (WUEt) were increased by elevated CO2, regardless of water status. Plant structural traits were also found to be tightly associated with photosynthetic potentials. The results indicated that CO2 enrichment alleviated severe and moderate drought stress, and highlighted that CO2 fertilization's dependency on water status should be considered when projecting key species' responses to climate change in dry ecosystems.

Coupled nutrient cycling determines tropical forest trajectory under elevated CO2.

Science.gov (United States)

Bouskill, N.; Zhu, Q.; Riley, W. J.

2017-12-01

Tropical forests have a disproportionate capacity to affect Earth's climate relative to their areal extent. Despite covering just 12 % of land surface, tropical forests account for 35 % of global net primary productivity and are among the most significant of terrestrial carbon stores. As atmospheric CO2 concentrations increase over the next century, the capacity of tropical forests to assimilate and sequester anthropogenic CO2 depends on limitation by multiple factors, including the availability of soil nutrients. Phosphorus availability has been considered to be the primary factor limiting metabolic processes within tropical forests. However, recent evidence points towards strong spatial and temporal co-limitation of tropical forests by both nitrogen and phosphorus. Here, we use the Accelerated Climate Modeling for Energy (ACME) Land Model (ALMv1-ECA-CNP) to examine how nutrient cycles interact and affect the trajectory of the tropical forest carbon sink under, (i) external nutrient input, (ii) climate (iii) elevated CO2, and (iv) a combination of 1-3. ALMv1 includes recent theoretical advances in representing belowground competition between roots, microbes and minerals for N and P uptake, explicit interactions between the nitrogen and phosphorus cycles (e.g., phosphatase production and nitrogen fixation), the dynamic internal allocation of plant N and P resources, and the integration of global datasets of plant physiological traits. We report nutrient fertilization (N, P, N+P) predictions for four sites in the tropics (El Verde, Puerto Rico, Barro Colorado Island, Panama, Manaus, Brazil and the Osa Peninsula, Coast Rica) to short-term nutrient fertilization (N, P, N+P), and benchmarking of the model against a meta-analysis of forest fertilization experiments. Subsequent simulations focus on the interaction of the carbon, nitrogen, and phosphorus cycles across the tropics with a focus on the implications of coupled nutrient cycling and the fate of the tropical

Elevated Temperature and CO2 Stimulate Late-Season Photosynthesis But Impair Cold Hardening in Pine[OPEN

Science.gov (United States)

2016-01-01

Rising global temperature and CO2 levels may sustain late-season net photosynthesis of evergreen conifers but could also impair the development of cold hardiness. Our study investigated how elevated temperature, and the combination of elevated temperature with elevated CO2, affected photosynthetic rates, leaf carbohydrates, freezing tolerance, and proteins involved in photosynthesis and cold hardening in Eastern white pine (Pinus strobus). We designed an experiment where control seedlings were acclimated to long photoperiod (day/night 14/10 h), warm temperature (22°C/15°C), and either ambient (400 μL L−1) or elevated (800 μmol mol−1) CO2, and then shifted seedlings to growth conditions with short photoperiod (8/16 h) and low temperature/ambient CO2 (LTAC), elevated temperature/ambient CO2 (ETAC), or elevated temperature/elevated CO2 (ETEC). Exposure to LTAC induced down-regulation of photosynthesis, development of sustained nonphotochemical quenching, accumulation of soluble carbohydrates, expression of a 16-kD dehydrin absent under long photoperiod, and increased freezing tolerance. In ETAC seedlings, photosynthesis was not down-regulated, while accumulation of soluble carbohydrates, dehydrin expression, and freezing tolerance were impaired. ETEC seedlings revealed increased photosynthesis and improved water use efficiency but impaired dehydrin expression and freezing tolerance similar to ETAC seedlings. Sixteen-kilodalton dehydrin expression strongly correlated with increases in freezing tolerance, suggesting its involvement in the development of cold hardiness in P. strobus. Our findings suggest that exposure to elevated temperature and CO2 during autumn can delay down-regulation of photosynthesis and stimulate late-season net photosynthesis in P. strobus seedlings. However, this comes at the cost of impaired freezing tolerance. Elevated temperature and CO2 also impaired freezing tolerance. However, unless the frequency and timing of extreme low

Arrangement of experiments for simulating the effects of elevated temperatures and elevated CO2 levels on field-sown crops in Finland

Directory of Open Access Journals (Sweden)

Kaija Hakala

1996-01-01

Full Text Available The experimental plants: spring wheat, winterwheat, spring barley, meadow fescue, potato, strawberry and black currant were sown or planted directly in the field, part of which was covered by an automatically controlled greenhouse to elevate the temperature by 3°C. The temperature of the other part of the field (open field was not elevated, but the field was covered with the same plastic film as the greenhouse to achieve radiation and rainfall conditions comparable to those in the greenhouse. To elevate the CO2 concentrations, four open top chambers (OTC were built for the greenhouse, and four for the open field. Two of these, both in the greenhouse and in the open field, were supplied with pure CO2 to elevate their CO2 level to 700 ppm. The temperatures inside the greenhouse followed accurately the desired level. The relative humidity was somewhat higher in the greenhouse and in the OTC:s than in the open field, especially after the modifications in the ventilation of the greenhouse and in the OTC:s in 1994. Because the OTC:s were large (3 m in diameter, the temperatures inside them differed very little from the surrounding air temperature. The short-term variation in the CO2 concentrations in the OTC:s with elevated CO2 was, however, quite high. The control of the CO2 concentrations improved each year from 1992 to 1994, as the CO2 supplying system was modified. The effects of the experimental conditions on plant growth and phenology are discussed.

Arrangement of experiments for simulating the effects of elevated temperatures and elevated CO2 levels on field-sown crops in Finland

Directory of Open Access Journals (Sweden)

K. HAKALA

2008-12-01

Full Text Available The experimental plants: spring wheat, winter wheat, spring barley, meadow fescue, potato, strawberry and black currant were sown or planted directly in the field, part of which was covered by an automatically controlled greenhouse to elevate the temperature by 3°C. The temperature of the other part of the field (open field was not elevated, but the field was covered with the same plastic film as the greenhouse to achieve radiation and rainfall conditions comparable to those in the greenhouse. To elevate the CO2 concentrations, four open top chambers (OTC were built for the greenhouse, and four for the open field. Two of these, both in the greenhouse and in the open field, were supplied with pure CO2 to elevate their CO2 level to 700 ppm. The temperatures inside the greenhouse followed accurately the desired level. The relative humidity was somewhat higher in the greenhouse and in the OTC:s than in the open field, especially after the modifications in the ventilation of the greenhouse and in the OTC:s in 1994. Because the OTC:s were large (3 m in diameter, the temperatures inside them differed very little from the surrounding air temperature. The short-term variation in the CO2 concentrations in the OTC:s with elevated CO2 was, however, quite high. The control of the CO2 concentrations improved each year from 1992 to 1994, as the CO2 supplying system was modified. The effects of the experimental conditions on plant growth and phenology are discussed.;

Elevated CO2-mitigation of high temperature stress associated with maintenance of positive carbon balance and carbohydrate accumulation in Kentucky bluegrass.

Science.gov (United States)

Song, Yali; Yu, Jingjin; Huang, Bingru

2014-01-01

Elevated CO2 concentration may promote plant growth while high temperature is inhibitory for C3 plant species. The interactive effects of elevated CO2 and high temperatures on C3 perennial grass growth and carbon metabolism are not well documented. Kentucky bluegrass (Poa pratensis) plants were exposed to two CO2 levels (400 and 800 μmol mol-1) and five temperatures (15/12, 20/17, 25/22, 30/27, 35/32°C, day/night) in growth chambers. Increasing temperatures to 25°C and above inhibited leaf photosynthetic rate (Pn) and shoot and root growth, but increased leaf respiration rate (R), leading to a negative carbon balance and a decline in soluble sugar content under ambient CO2. Elevated CO2 did not cause shift of optimal temperatures in Kentucky bluegrass, but promoted Pn, shoot and root growth under all levels of temperature (15, 20, 25, 30, and 35°C) and mitigated the adverse effects of severe high temperatures (30 and 35°C). Elevated CO2-mitigation of adverse effects of high temperatures on Kentucky bluegrass growth could be associated with the maintenance of a positive carbon balance and the accumulation of soluble sugars and total nonstructural carbohydrates through stimulation of Pn and suppression of R and respiratory organic acid metabolism.

EFFECTS OF ELEVATED CO2 AND TEMPERATURE ON SOIL CARBON DENSITY FRACTIONS IN A DOUGLAS FIR MESOCOSM STUDY

Science.gov (United States)

We conducted a 4-year full-factorial study of the effects of elevated atmospheric CO2 and temperature on Douglas fir seedlings growing in reconstructed native forest soils in mesocosms. The elevated CO2 treatment was ambient CO2 plus 200 ppm CO2. The elevated temperature treatm...

Does low stomatal conductance or photosynthetic capacity enhance growth at elevated CO2 in Arabidopsis?

Science.gov (United States)

Easlon, Hsien Ming; Carlisle, Eli; McKay, John K; Bloom, Arnold J

2015-03-01

The objective of this study was to determine if low stomatal conductance (g) increases growth, nitrate (NO3 (-)) assimilation, and nitrogen (N) utilization at elevated CO2 concentration. Four Arabidopsis (Arabidopsis thaliana) near isogenic lines (NILs) differing in g were grown at ambient and elevated CO2 concentration under low and high NO3 (-) supply as the sole source of N. Although g varied by 32% among NILs at elevated CO2, leaf intercellular CO2 concentration varied by only 4% and genotype had no effect on shoot NO3 (-) concentration in any treatment. Low-g NILs showed the greatest CO2 growth increase under N limitation but had the lowest CO2 growth enhancement under N-sufficient conditions. NILs with the highest and lowest g had similar rates of shoot NO3 (-) assimilation following N deprivation at elevated CO2 concentration. After 5 d of N deprivation, the lowest g NIL had 27% lower maximum carboxylation rate and 23% lower photosynthetic electron transport compared with the highest g NIL. These results suggest that increased growth of low-g NILs under N limitation most likely resulted from more conservative N investment in photosynthetic biochemistry rather than from low g. © 2015 American Society of Plant Biologists. All Rights Reserved.

A MIXED MODEL ANALYSIS OF SOIL CO2 EFFLUX AND NIGHT-TIME RESPIRATION RESPONSES TO ELEVATED CO2 AND TEMPERATURE

Science.gov (United States)

Abstract: We investigated the effects of elevated soil temperature and atmospheric CO2 on soil CO2 efflux and system respiration responses. The study was conducted in sun-lit controlled-environment chambers using two-year-old Douglas-fir seedlings grown in reconstructed litter-so...

Elevated atmospheric CO2 in a semi-natural grassland: Root dynamics, decomposition and soil C balances

International Nuclear Information System (INIS)

Sindhoej, Erik

2001-01-01

This thesis focuses on how elevated atmospheric CO 2 affects a semi-natural grassland, with emphasis on root growth, decomposition and the subsequent long-term effects on soil C balances. Parts of a semi-natural grassland in Central Sweden were enclosed in open-top chambers and exposed to ambient and elevated levels of CO 2 (+350 μmol mol -1 ) from 1995 to 2000, while chamberless rings were used for controls. Root dynamics were observed with minirhizotrons while root biomass and production were studied with soil cores and ingrowth cores. Roots collected from ingrowth cores were incubated under controlled conditions for 160 days to measure root decomposition rates. Treatment-induced differences in microclimate, C input and root decomposability were entered into the ICBM soil C balance model for 30-year projections of soil C balances for the three treatments. Elevated CO 2 chambers had higher biomass production both above and below ground compared to ambient, however the root response increased over the years while the shoot response decreased. Plants grown under elevated CO 2 had greater water-use efficiency compared to ambient, which was shown in higher soil moisture and greater biomass production during slightly dry years. Elevated CO 2 chambers showed higher root appearance rates in spring and higher disappearance rates during autumn and winter. Roots from plants grown under elevated CO 2 decomposed more rapidly. The decreased input and the drier conditions in the ambient chambers were projected to lead to a 1.7% decrease in soil C over 30 years. Under elevated CO 2 , however, the increased input compensated for the higher root decomposability and moister soil conditions and lead only to a projected 1.3% decrease in soil C. This work shows that six years of elevated CO 2 exposure had extensive effects on this semi-natural grassland. The CO 2 response of the grassland was dependent on weather conditions and production increased most when under slight water stress

Cycling-induced degradation of LiCoO2 thin-film cathodes at elevated temperature

International Nuclear Information System (INIS)

Van Sluytman, J.S.; West, W.C.; Whitacre, J.F.; Alamgir, F.M.; Greenbaum, S.G.

2006-01-01

The cycle life of LiCoO 2 -based all solid-state thin-film cells has been studied at room temperature, and at elevated temperatures of 50, 100, and 150 deg. C. X-ray diffraction, as well as Raman analysis, has been used to complement the electrochemical data in examining structural and chemical changes. XRD and Raman spectroscopy data indicate that elevated temperature soaks of the thin-film batteries in the quiescent state causes no discernable changes in the LiCoO 2 cathode layer. However, when the thin-film batteries are cycled at elevated temperatures, decreases in average grain size of the LiCoO 2 film occur with dramatic concomitant charge and discharge capacity loss

Improving yield potential in crops under elevated CO(2): Integrating the photosynthetic and nitrogen utilization efficiencies.

Science.gov (United States)

Kant, Surya; Seneweera, Saman; Rodin, Joakim; Materne, Michael; Burch, David; Rothstein, Steven J; Spangenberg, German

2012-01-01

Increasing crop productivity to meet burgeoning human food demand is challenging under changing environmental conditions. Since industrial revolution atmospheric CO(2) levels have linearly increased. Developing crop varieties with increased utilization of CO(2) for photosynthesis is an urgent requirement to cope with the irreversible rise of atmospheric CO(2) and achieve higher food production. The primary effects of elevated CO(2) levels in most crop plants, particularly C(3) plants, include increased biomass accumulation, although initial stimulation of net photosynthesis rate is only temporal and plants fail to sustain the maximal stimulation, a phenomenon known as photosynthesis acclimation. Despite this acclimation, grain yield is known to marginally increase under elevated CO(2). The yield potential of C(3) crops is limited by their capacity to exploit sufficient carbon. The "C fertilization" through elevated CO(2) levels could potentially be used for substantial yield increase. Rubisco is the rate-limiting enzyme in photosynthesis and its activity is largely affected by atmospheric CO(2) and nitrogen availability. In addition, maintenance of the C/N ratio is pivotal for various growth and development processes in plants governing yield and seed quality. For maximizing the benefits of elevated CO(2), raising plant nitrogen pools will be necessary as part of maintaining an optimal C/N balance. In this review, we discuss potential causes for the stagnation in yield increases under elevated CO(2) levels and explore possibilities to overcome this limitation by improved photosynthetic capacity and enhanced nitrogen use efficiency. Opportunities of engineering nitrogen uptake, assimilatory, and responsive genes are also discussed that could ensure optimal nitrogen allocation toward expanding source and sink tissues. This might avert photosynthetic acclimation partially or completely and drive for improved crop production under elevated CO(2) levels.

Improving yield potential in crops under elevated CO2: Integrating the photosynthetic and nitrogen utilization efficiencies

Science.gov (United States)

Kant, Surya; Seneweera, Saman; Rodin, Joakim; Materne, Michael; Burch, David; Rothstein, Steven J.; Spangenberg, German

2012-01-01

Increasing crop productivity to meet burgeoning human food demand is challenging under changing environmental conditions. Since industrial revolution atmospheric CO2 levels have linearly increased. Developing crop varieties with increased utilization of CO2 for photosynthesis is an urgent requirement to cope with the irreversible rise of atmospheric CO2 and achieve higher food production. The primary effects of elevated CO2 levels in most crop plants, particularly C3 plants, include increased biomass accumulation, although initial stimulation of net photosynthesis rate is only temporal and plants fail to sustain the maximal stimulation, a phenomenon known as photosynthesis acclimation. Despite this acclimation, grain yield is known to marginally increase under elevated CO2. The yield potential of C3 crops is limited by their capacity to exploit sufficient carbon. The “C fertilization” through elevated CO2 levels could potentially be used for substantial yield increase. Rubisco is the rate-limiting enzyme in photosynthesis and its activity is largely affected by atmospheric CO2 and nitrogen availability. In addition, maintenance of the C/N ratio is pivotal for various growth and development processes in plants governing yield and seed quality. For maximizing the benefits of elevated CO2, raising plant nitrogen pools will be necessary as part of maintaining an optimal C/N balance. In this review, we discuss potential causes for the stagnation in yield increases under elevated CO2 levels and explore possibilities to overcome this limitation by improved photosynthetic capacity and enhanced nitrogen use efficiency. Opportunities of engineering nitrogen uptake, assimilatory, and responsive genes are also discussed that could ensure optimal nitrogen allocation toward expanding source and sink tissues. This might avert photosynthetic acclimation partially or completely and drive for improved crop production under elevated CO2 levels. PMID:22833749

Unique responsiveness of angiosperm stomata to elevated CO2 explained by calcium signalling.

Directory of Open Access Journals (Sweden)

Timothy J Brodribb

Full Text Available Angiosperm and conifer tree species respond differently when exposed to elevated CO2, with angiosperms found to dynamically reduce water loss while conifers appear insensitive. Such distinct responses are likely to affect competition between these tree groups as atmospheric CO2 concentration rises. Seeking the mechanism behind this globally important phenomenon we targeted the Ca(2+-dependent signalling pathway, a mediator of stomatal closure in response to elevated CO2, as a possible explanation for the differentiation of stomatal behaviours. Sampling across the diversity of vascular plants including lycophytes, ferns, gymnosperms and angiosperms we show that only angiosperms possess the stomatal behaviour and prerequisite genetic coding, linked to Ca(2+-dependent stomatal signalling. We conclude that the evolution of Ca(2+-dependent stomatal signalling gives angiosperms adaptive benefits in terms of highly efficient water use, but that stomatal sensitivity to high CO2 may penalise angiosperm productivity relative to other plant groups in the current era of soaring atmospheric CO2.

Productivity responses of Acer rubrum and Taxodium distichum seedlings to elevated CO2 and flooding

Science.gov (United States)

Vann, C.D.; Megonigal, J.P.

2002-01-01

Elevated levels of atmospheric CO2 are expected to increase photosynthetic rates of C3 tree species, but it is uncertain whether this will result in an increase in wetland seedling productivity. Separate short-term experiments (12 and 17 weeks) were performed on two wetland tree species, Taxodium distichum and Acer rubrum, to determine if elevated CO2 would influence the biomass responses of seedlings to flooding. T. distichum were grown in replicate glasshouses (n = 2) at CO2 concentrations of 350 or 700 ppm, and A. rubrum were grown in growth chambers at CO2 concentrations of 422 or 722 ppm. Both species were grown from seed. The elevated CO2 treatment was crossed with two water table treatments, flooded and non-flooded. Elevated CO2 increased leaf-level photosynthesis, whole-plant photosynthesis, and trunk diameter of T. distichum in both flooding treatments, but did not increase biomass of T. distichum or A. rubrum. Flooding severely reduced biomass, height, and leaf area of both T. distichum and A. rubrum. Our results suggest that the absence of a CO2-induced increase in growth may have been due to an O2 limitation on root production even though there was a relatively deep (??? 10 cm) aerobic soil surface in the non-flooded treatment. ?? 2001 Elsevier Science Ltd. All rights reserved.

Monoterpene and herbivore-induced emissions from cabbage plants grown at elevated atmospheric CO 2 concentration

Science.gov (United States)

Vuorinen, Terhi; Reddy, G. V. P.; Nerg, Anne-Marja; Holopainen, Jarmo K.

The warming of the lower atmosphere due to elevating CO 2 concentration may increase volatile organic compound (VOC) emissions from plants. Also, direct effects of elevated CO 2 on plant secondary metabolism are expected to lead to increased VOC emissions due to allocation of excess carbon on secondary metabolites, of which many are volatile. We investigated how growing at doubled ambient CO 2 concentration affects emissions from cabbage plants ( Brassica oleracea subsp. capitata) damaged by either the leaf-chewing larvae of crucifer specialist diamondback moth ( Plutella xylostella L.) or generalist Egyptian cotton leafworm ( Spodoptera littoralis (Boisduval)). The emission from cabbage cv. Lennox grown in both CO 2 concentrations, consisted mainly of monoterpenes (sabinene, limonene, α-thujene, 1,8-cineole, β-pinene, myrcene, α-pinene and γ-terpinene). ( Z)-3-Hexenyl acetate, sesquiterpene ( E, E)- α-farnesene and homoterpene ( E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were emitted mainly from herbivore-damaged plants. Plants grown at 720 μmol mol -1 of CO 2 had significantly lower total monoterpene emissions per shoot dry weight than plants grown at 360 μmol mol -1 of CO 2, while damage by both herbivores significantly increased the total monoterpene emissions compared to intact plants. ( Z)-3-Hexenyl acetate, ( E, E)- α-farnesene and DMNT emissions per shoot dry weight were not affected by the growth at elevated CO 2. The emission of DMNT was significantly enhanced from plants damaged by the specialist P. xylostella compared to the plants damaged by the generalist S. littoralis. The relative proportions of total monoterpenes and total herbivore-induced compounds of total VOCs did not change due to the growth at elevated CO 2, while insect damage increased significantly the proportion of induced compounds. The results suggest that VOC emissions that are induced by the leaf-chewing herbivores will not be influenced by elevated CO 2 concentration.

Elevated CO2 Reduced Floret Death in Wheat Under Warmer Average Temperatures and Terminal Drought

Science.gov (United States)

Dias de Oliveira, Eduardo; Palta, Jairo A.; Bramley, Helen; Stefanova, Katia; Siddique, Kadambot H. M.

2015-01-01

Elevated CO2 often increases grain yield in wheat by enhancing grain number per ear, which can result from an increase in the potential number of florets or a reduction in the death of developed florets. The hypotheses that elevated CO2 reduces floret death rather than increases floret development, and that grain size in a genotype with more grains per unit area is limited by the rate of grain filling, were tested in a pair of sister lines contrasting in tillering capacity (restricted- vs. free-tillering). The hypotheses were tested under elevated CO2, combined with +3°C above ambient temperature and terminal drought, using specialized field tunnel houses. Elevated CO2 increased net leaf photosynthetic rates and likely the availability of carbon assimilates, which significantly reduced the rates of floret death and increased the potential number of grains at anthesis in both sister lines by an average of 42%. The restricted-tillering line had faster grain-filling rates than the free-tillering line because the free-tillering line had more grains to fill. Furthermore, grain-filling rates were faster under elevated CO2 and +3°C above ambient. Terminal drought reduced grain yield in both lines by 19%. Elevated CO2 alone increased the potential number of grains, but a trade-off in yield components limited grain yield in the free-tillering line. This emphasizes the need for breeding cultivars with a greater potential number of florets, since this was not affected by the predicted future climate variables. PMID:26635837

Elevated CO2 reduced floret death in wheat under warmer average temperatures and terminal drought.

Directory of Open Access Journals (Sweden)

Eduardo eDias de Oliveira

2015-11-01

Full Text Available Elevated CO2 often increases grain yield in wheat by enhancing grain number per ear, which can result from an increase in the potential number of florets or a reduction in the death of developed florets. The hypotheses that elevated CO2 reduces floret death rather than increases floret development, and that grain size in a genotype with more grains per unit area is limited by the rate of grain filling, were tested in a pair of sister lines contrasting in tillering capacity (restricted- vs free-tillering. The hypotheses were tested under elevated CO2, combined with +3 C above ambient temperature and terminal drought, using specialized field tunnel houses. Elevated CO2 increased net leaf photosynthetic rates and likely the availability of carbon assimilates, which significantly reduced the rates of floret death and increased the potential number of grains at anthesis in both sister lines by an average of 42%. The restricted-tillering line had faster grain-filling rates than the free-tillering line because the free-tillering line had more grains to fill. Furthermore, grain-filling rates were faster under elevated CO2 and +3 C above ambient. Terminal drought reduced grain yield in both lines by 19%. Elevated CO2 alone increased the potential number of grains, but a trade-off in yield components limited grain yield in the free-tillering line. This emphasizes the need for breeding cultivars with a greater potential number of florets, since this was not affected by the predicted future climate variables.

Does an elevated CO₂ concentration decrease dark respiration in trees? Final technical report

Energy Technology Data Exchange (ETDEWEB)

Long, Stephen [Univ. of Illinois, Urbana-Champaign, IL (United States)

2003-12-31

Averaged across many previous investigations, doubling the CO₂ concentration ([CO₂]) has frequently been reported to cause an instantaneous reduction of leaf dark respiration measured as CO₂ efflux. No known mechanism accounts for this effect. While four recent studies have shown that the measurement of respiratory CO₂ efflux is prone to experimental artifacts that could account for the reported response, papers published since the start of the current research continue to report an instantaneous depression of respiratory CO₂ efflux by elevation of [CO₂]. Here, these artifacts are avoided by use of a high-resolution dual channel oxygen analyzer within an open gas exchange system to measure respiratory 02 uptake in normal air. Leaf 02 uptake was determined in response to instantaneous elevation of [CO₂] in nine contrasting species and to long-term elevation in seven species from four of the DOE-sponsored long-term elevated [CO₂] field experiments. Over one thousand separate measurements of respiration failed to reveal any decrease in respiratory 02 uptake with an instantaneous increase in [CO₂]. Respiration was found insensitive not only to doubling [CO₂], but also to a five-fold increase and to decrease to zero.

Effect of Elevated CO2 Concentration, Elevated Temperature and No Nitrogen Fertilization on Methanogenic Archaeal and Methane-Oxidizing Bacterial Community Structures in Paddy Soil.

Science.gov (United States)

Liu, Dongyan; Tago, Kanako; Hayatsu, Masahito; Tokida, Takeshi; Sakai, Hidemitsu; Nakamura, Hirofumi; Usui, Yasuhiro; Hasegawa, Toshihiro; Asakawa, Susumu

2016-09-29

Elevated concentrations of atmospheric CO2 ([CO2]) enhance the production and emission of methane in paddy fields. In the present study, the effects of elevated [CO2], elevated temperature (ET), and no nitrogen fertilization (LN) on methanogenic archaeal and methane-oxidizing bacterial community structures in a free-air CO2 enrichment (FACE) experimental paddy field were investigated by PCR-DGGE and real-time quantitative PCR. Soil samples were collected from the upper and lower soil layers at the rice panicle initiation (PI) and mid-ripening (MR) stages. The composition of the methanogenic archaeal community in the upper and lower soil layers was not markedly affected by the elevated [CO2], ET, or LN condition. The abundance of the methanogenic archaeal community in the upper and lower soil layers was also not affected by elevated [CO2] or ET, but was significantly increased at the rice PI stage and significantly decreased by LN in the lower soil layer. In contrast, the composition of the methane-oxidizing bacterial community was affected by rice-growing stages in the upper soil layer. The abundance of methane-oxidizing bacteria was significantly decreased by elevated [CO2] and LN in both soil layers at the rice MR stage and by ET in the upper soil layer. The ratio of mcrA/pmoA genes correlated with methane emission from ambient and FACE paddy plots at the PI stage. These results indicate that the decrease observed in the abundance of methane-oxidizing bacteria was related to increased methane emission from the paddy field under the elevated [CO2], ET, and LN conditions.

The effect of heat waves, elevated [CO2 ] and low soil water availability on northern red oak (Quercus rubra L.) seedlings.

Science.gov (United States)

Bauweraerts, Ingvar; Wertin, Timothy M; Ameye, Maarten; McGuire, Mary Anne; Teskey, Robert O; Steppe, Kathy

2013-02-01

The frequency and intensity of heat waves are predicted to increase. This study investigates whether heat waves would have the same impact as a constant increase in temperature with the same heat sum, and whether there would be any interactive effects of elevated [CO2 ] and soil moisture content. We grew Quercus rubra seedlings in treatment chambers maintained at either ambient or elevated [CO2 ] (380 or 700 μmol CO2 mol(-1) ) with temperature treatments of ambient, ambient +3 °C, moderate heat wave (+6 °C every other week) or severe heat wave (+12 °C every fourth week) temperatures. Averaged over a 4-week period, and the entire growing season, the three elevated temperature treatments had the same average temperature and heat sum. Half the seedlings were watered to a soil water content near field capacity, half to about 50% of this value. Foliar gas exchange measurements were performed morning and afternoon (9:00 and 15:00 hours) before, during and after an applied heat wave in August 2010. Biomass accumulation was measured after five heat wave cycles. Under ambient [CO2 ] and well-watered conditions, biomass accumulation was highest in the +3 °C treatment, intermediate in the +6 °C heat wave and lowest in the +12 °C heat wave treatment. This response was mitigated by elevated [CO2 ]. Low soil moisture significantly decreased net photosynthesis (Anet ) and biomass in all [CO2 ] and temperature treatments. The +12 °C heat wave reduced afternoon Anet by 23% in ambient [CO2 ]. Although this reduction was relatively greater under elevated [CO2 ], Anet values during this heat wave were still 34% higher than under ambient [CO2 ]. We concluded that heat waves affected biomass growth differently than the same amount of heat applied uniformly over the growing season, and that the plant response to heat waves also depends on [CO2 ] and soil moisture conditions. © 2012 Blackwell Publishing Ltd.

The counteracting effects of elevated atmospheric CO2 concentrations and drought episodes: Studies of enchytraeid communities in a dry heathland

DEFF Research Database (Denmark)

Maraldo, Kristine; Krogh, Paul Henning; Linden, Leon

2010-01-01

The potential impacts of interactions of multiple climate change factors in soil ecosystems have received little attention. Most studies have addressed effects of single factors such as increased temperature or atmospheric CO2 but little is known about how such environmental factors will interact...... impact of drought on the enchytraeids, compared to the year with a wet summer and autumn (2007). Our study emphasises the importance of multi-factorial experimental design as a means to investigate effects of climatic changes.......The potential impacts of interactions of multiple climate change factors in soil ecosystems have received little attention. Most studies have addressed effects of single factors such as increased temperature or atmospheric CO2 but little is known about how such environmental factors will interact....... In the present study we investigate the effects of in situ exposure to elevated atmospheric CO2 concentration, increased temperatures and prolonged drought episodes on field communities of Enchytraeidae (Oligochaeta) in a dry heathland (Brandbjerg, Denmark). Increased CO2 had a positive effect on enchytraeid...

Microbe-driven turnover offsets mineral-mediated storage of soil carbon under elevated CO2

Science.gov (United States)

Sulman, Benjamin N.; Phillips, Richard P.; Oishi, A. Christopher; Shevliakova, Elena; Pacala, Stephen W.

2014-12-01

The sensitivity of soil organic carbon (SOC) to changing environmental conditions represents a critical uncertainty in coupled carbon cycle-climate models. Much of this uncertainty arises from our limited understanding of the extent to which root-microbe interactions induce SOC losses (through accelerated decomposition or `priming') or indirectly promote SOC gains (via `protection' through interactions with mineral particles). We developed a new SOC model to examine priming and protection responses to rising atmospheric CO2. The model captured disparate SOC responses at two temperate free-air CO2 enrichment (FACE) experiments. We show that stabilization of `new' carbon in protected SOC pools may equal or exceed microbial priming of `old' SOC in ecosystems with readily decomposable litter and high clay content (for example, Oak Ridge). In contrast, carbon losses induced through priming dominate the net SOC response in ecosystems with more resistant litters and lower clay content (for example, Duke). The SOC model was fully integrated into a global terrestrial carbon cycle model to run global simulations of elevated CO2 effects. Although protected carbon provides an important constraint on priming effects, priming nonetheless reduced SOC storage in the majority of terrestrial areas, partially counterbalancing SOC gains from enhanced ecosystem productivity.

Response of free-living soil protozoa and microorganisms to elevated atmospheric CO2 and presence of mycorrhiza

DEFF Research Database (Denmark)

Rønn, R.; Gavito, M.; Larsen, J.

2002-01-01

with or without the presence of the arbuscular mycorrhizal (AM) fungus Glomus caledonium. It was hypothesised that (1) the populations of free-living soil protozoa would increase as a response to elevated CO2, (2) the effect of elevated CO2 on protozoa would be moderated by the presence of mycorrhiza and (3......) the presence of arbuscular mycorrhiza would affect soil protozoan numbers regardless of atmospheric CO2. After 3 weeks growth there was no difference in bacterial numbers (direct counts) in soil, but the number of free-living bacterial-feeding protozoa was significantly higher under elevated CO2...... elevated CO2 suggest increased bacterial production, whereas the lower populations in response to presence of mycorrhiza suggest a depressing effect on bacterial production by AM colonisation. (C) 2002 Elsevier Science Ltd. All rights reserved....

Effects of long-term elevated atmospheric CO2 concentrations on Pinus ponderosa

International Nuclear Information System (INIS)

Surano, K.A.; Kercher, J.R.

1993-01-01

This report details the results from an experiment of the effects of long-term elevated atmospheric CO 2 concentrations on ponderosa pine (Pinus ponderosa Laws.) saplings and seedlings. The study began in 1983 as a pilot study designed to explore the feasibility of using open-top chambers for continuous multi-year exposures on sapling-sized trees and to examine possible CO 2 responses so that future research could be adequately designed. however, following the first year of exposure, preliminary results from the study indicated that measurements of CO 2 responses should be intensified. Open-top chambers proved suitable for use in multiyear exposures of mature trees. With respect to the preliminary examination of CO 2 responses, many interesting observations were made. The nature of the preliminary results suggests that future long-term field CO 2 exposures on perennial species may be critical to the understanding and preparation for future environments. Other research reported here attempted to adapt an existing western coniferous forest growth and succession model for use in elevated CO 2 scenarios using differential species responses, and assessed the usefulness of the model in that regard. Seven papers have been processed separately for inclusion in the appropriate data bases

Effects of fully open-air [CO2] elevation on leaf photosynthesis and ultrastructure of Isatis indigotica fort.

Science.gov (United States)

Hao, Xingyu; Li, Ping; Feng, Yongxiang; Han, Xue; Gao, Ji; Lin, Erda; Han, Yuanhuai

2013-01-01

Traditional Chinese medicine relies heavily on herbs, yet there is no information on how these herb plants would respond to climate change. In order to gain insight into such response, we studied the effect of elevated [CO2] on Isatis indigotica Fort, one of the most popular Chinese herb plants. The changes in leaf photosynthesis, chlorophyll fluorescence, leaf ultrastructure and biomass yield in response to elevated [CO2] (550±19 µmol mol(-1)) were determined at the Free-Air Carbon dioxide Enrichment (FACE) experimental facility in North China. Photosynthetic ability of I. indigotica was improved under elevated [CO2]. Elevated [CO2] increased net photosynthetic rate (P N), water use efficiency (WUE) and maximum rate of electron transport (J max) of upper most fully-expended leaves, but not stomatal conductance (gs), transpiration ratio (Tr) and maximum velocity of carboxylation (V c,max). Elevated [CO2] significantly increased leaf intrinsic efficiency of PSII (Fv'/Fm') and quantum yield of PSII(ΦPS II ), but decreased leaf non-photochemical quenching (NPQ), and did not affect leaf proportion of open PSII reaction centers (qP) and maximum quantum efficiency of PSII (Fv/Fm). The structural chloroplast membrane, grana layer and stroma thylakoid membranes were intact under elevated [CO2], though more starch grains were accumulated within the chloroplasts than that of under ambient [CO2]. While the yield of I. indigotica was higher due to the improved photosynthesis under elevated [CO2], the content of adenosine, one of the functional ingredients in indigowoad root was not affected.

Arbuscular mycorrhiza improve growth, nitrogen uptake, and nitrogen use efficiency in wheat grown under elevated CO2.

Science.gov (United States)

Zhu, Xiancan; Song, Fengbin; Liu, Shengqun; Liu, Fulai

2016-02-01

Effects of the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis on plant growth, carbon (C) and nitrogen (N) accumulation, and partitioning was investigated in Triticum aestivum L. plants grown under elevated CO2 in a pot experiment. Wheat plants inoculated or not inoculated with the AM fungus were grown in two glasshouse cells with different CO2 concentrations (400 and 700 ppm) for 10 weeks. A (15)N isotope labeling technique was used to trace plant N uptake. Results showed that elevated CO2 increased AM fungal colonization. Under CO2 elevation, AM plants had higher C concentration and higher plant biomass than the non-AM plants. CO2 elevation did not affect C and N partitioning in plant organs, while AM symbiosis increased C and N allocation into the roots. In addition, plant C and N accumulation, (15)N recovery rate, and N use efficiency (NUE) were significantly higher in AM plants than in non-AM controls under CO2 enrichment. It is concluded that AM symbiosis favors C and N partitioning in roots, increases C accumulation and N uptake, and leads to greater NUE in wheat plants grown at elevated CO2.

Elevated CO2 plus chronic warming reduce nitrogen uptake and levels or activities of nitrogen-uptake and -assimilatory proteins in tomato roots.

Science.gov (United States)

Jayawardena, Dileepa M; Heckathorn, Scott A; Bista, Deepesh R; Mishra, Sasmita; Boldt, Jennifer K; Krause, Charles R

2017-03-01

Atmospheric CO 2 enrichment is expected to often benefit plant growth, despite causing global warming and nitrogen (N) dilution in plants. Most plants primarily procure N as inorganic nitrate (NO 3 - ) or ammonium (NH 4 + ), using membrane-localized transport proteins in roots, which are key targets for improving N use. Although interactive effects of elevated CO 2 , chronic warming and N form on N relations are expected, these have not been studied. In this study, tomato (Solanum lycopersicum) plants were grown at two levels of CO 2 (400 or 700 ppm) and two temperature regimes (30 or 37°C), with NO 3 - or NH 4 + as the N source. Elevated CO 2 plus chronic warming severely inhibited plant growth, regardless of N form, while individually they had smaller effects on growth. Although %N in roots was similar among all treatments, elevated CO 2 plus warming decreased (1) N-uptake rate by roots, (2) total protein concentration in roots, indicating an inhibition of N assimilation and (3) shoot %N, indicating a potential inhibition of N translocation from roots to shoots. Under elevated CO 2 plus warming, reduced NO 3 - -uptake rate per g root was correlated with a decrease in the concentration of NO 3 - -uptake proteins per g root, reduced NH 4 + uptake was correlated with decreased activity of NH 4 + -uptake proteins and reduced N assimilation was correlated with decreased concentration of N-assimilatory proteins. These results indicate that elevated CO 2 and chronic warming can act synergistically to decrease plant N uptake and assimilation; hence, future global warming may decrease both plant growth and food quality (%N). © 2016 Scandinavian Plant Physiology Society.

Leaf quality and insect herbivory in model tropical plant communities after long-term exposure to elevated atmospheric CO2.

Science.gov (United States)

Arnone, J A; Zaller, J G; Körner, Ch; Ziegler, C; Zandt, H

1995-09-01

Results from laboratory feeding experiments have shown that elevated atmospheric carbon dioxide can affect interactions between plants and insect herbivores, primarily through changes in leaf nutritional quality occurring at elevated CO 2 . Very few data are available on insect herbivory in plant communities where insects can choose among species and positions in the canopy in which to feed. Our objectives were to determine the extent to which CO 2 -induced changes in plant communities and leaf nutritional quality may affect herbivory at the level of the entire canopy. We introduced equivalent populations of fourth instar Spodoptera eridania, a lepidopteran generalist, to complex model ecosystems containing seven species of moist tropical plants maintained under low mineral nutrient supply. Larvae were allowed to feed freely for 14 days, by which time they had reached the seventh instar. Prior to larval introductions, plant communities had been continuously exposed to either 340 μl CO 2 l -1 or to 610 μl CO 2 l -1 for 1.5 years. No major shifts in leaf nutritional quality [concentrations of N, total non-structural carbohydrates (TNC), sugar, and starch; ratios of: C/N, TNC/N, sugar/N, starch/N; leaf toughness] were observed between CO 2 treatments for any of the species. Furthermore, no correlations were observed between these measures of leaf quality and leaf biomass consumption. Total leaf area and biomass of all plant communities were similar when caterpillars were introduced. However, leaf biomass of some species was slightly greater-and for other species slightly less (e.g. Cecropia peltata)-in communities exposed to elevated CO 2 . Larvae showed the strongest preference for C. peltata leaves, the plant species that was least abundant in all communites, and fed relatively little on plants species which were more abundant. Thus, our results indicate that leaf tissue quality, as described by these parameters, is not necessarily affected by elevated CO 2 under

DO ELEVATED CO2 AND N FERTILIZATION ALTER FINE ROOT-MYCORRHIZAE RELATIONSHIPS IN PINUS PONDEROSA?

Science.gov (United States)

Despite extensive studies on the response of plants to elevated CO2, climate change and N deposition, little is known about the response of roots and mycorrhizae in spite of their key role in plant water and nutrient acquisition. The effects of elevated CO2 and N fertilization on...

Response of vegetation to carbon dioxide - sorghum at elevated levels of CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Burnett, R.B.; Chaudhuri, U.N.; Kanemasu, E.T.; Kirkham, M.B.

1985-12-31

Enhancement of plant growth is an important effect of the rising concentration of atmospheric CO{sub 2}. Crops vary in response to elevated CO{sub 2}. Growth often appears greater in C{sub 3} plants than in C{sub 4} plants. But relatively little work has been done with C{sub 4} plants, and most of it has been with corn. The few existing C{sub 4} data conflict. Some studies indicate that the yield of C{sub 4} plants at elevated CO{sub 2} is about one-fourth that of C{sub 3} crops, but other studies show that C{sub 4} plants with increased CO{sub 2} yield at a rate the average for all crops.

Response to elevated CO2 in the temperate C3 grass Festuca arundinaceae across ten soil orders

Directory of Open Access Journals (Sweden)

Eric A Nord

2015-02-01

Full Text Available Soils vary widely in mineral nutrient availability and physical characteristics, but the influence of this variability on plant responses to elevated CO2 remains poorly understood. As a first approximation of the effect of global soil variability on plant growth response to CO2, we evaluated the effect of CO2 on tall fescue (Festuca arundinacea grown in soils representing 10 of the 12 global soil orders plus a high-fertility control. Plants were grown in small pots in continuously stirred reactor tanks in a greenhouse. Elevated CO2 (800 ppm increased plant biomass in the high-fertility control and in two of the more fertile soils. Elevated CO2 had variable effects on foliar mineral concentration - nitrogen was not altered by elevated CO2, and phosphorus and potassium were only affected by CO2 in a small number of soils. While leaf photosynthesis was stimulated by elevated CO2 in six soils, canopy photosynthesis was not stimulated. Four principle components were identified; the first was associated with foliar minerals and soil clay, and the second with soil acidity and foliar manganese concentration. The third principle component was associated with gas exchange, and the fourth with plant biomass and soil minerals. Soils in which tall fescue did not respond to elevated CO2 account for 83% of global land area. These results show that variation in soil physical and chemical properties have important implications for plant responses to global change, and highlight the need to consider soil variability in models of vegetation response to global change.

Rangeland -- Plant response to elevated CO{sub 2}. Progress report

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-08-01

An experiment is being designed to examine the influence of elevating CO2 levels on tallgrass prairie rangeland. Changes in biomass production, photosynthesis rates, and species composition (C3 versus C4) over time are to be examined. This report covers the period from August 15, 1988 to January 1, 1989. During this period the authors have had planning meetings in Manhattan, KS, and Washington, DC, with various investigators of the measurement and modeling groups within the elevated CO{sub 2} program. During this period detailed discussions with regard to the methodology were carried out. In addition, short-term experiments and prototype constructions were completed to assess design and materials. Because of changes in the methodology and, to a certain degree, the scope, they are requesting changes in the funding cycle to implement the project at the beginning of the growing cycle of the tallgrass prairie.

Co-ordination of physiological and morphological responses of stomata to elevated [CO2] in vascular plants.

Science.gov (United States)

Haworth, Matthew; Elliott-Kingston, Caroline; McElwain, Jennifer C

2013-01-01

Plant stomata display a wide range of short-term behavioural and long-term morphological responses to atmospheric carbon dioxide concentration ([CO(2)]). The diversity of responses suggests that plants may have different strategies for controlling gas exchange, yet it is not known whether these strategies are co-ordinated in some way. Here, we test the hypothesis that there is co-ordination of physiological (via aperture change) and morphological (via stomatal density change) control of gas exchange by plants. We examined the response of stomatal conductance (G(s)) to instantaneous changes in external [CO(2)] (C(a)) in an evolutionary cross-section of vascular plants grown in atmospheres of elevated [CO(2)] (1,500 ppm) and sub-ambient [O(2)] (13.0 %) compared to control conditions (380 ppm CO(2), 20.9 % O(2)). We found that active control of stomatal aperture to [CO(2)] above current ambient levels was not restricted to angiosperms, occurring in the gymnosperms Lepidozamia peroffskyana and Nageia nagi. The angiosperm species analysed appeared to possess a greater respiratory demand for stomatal movement than gymnosperm species displaying active stomatal control. Those species with little or no control of stomatal aperture (termed passive) to C(a) were more likely to exhibit a reduction in stomatal density than species with active stomatal control when grown in atmospheres of elevated [CO(2)]. The relationship between the degree of stomatal aperture control to C(a) above ambient and the extent of any reduction in stomatal density may suggest the co-ordination of physiological and morphological responses of stomata to [CO(2)] in the optimisation of water use efficiency. This trade-off between stomatal control strategies may have developed due to selective pressures exerted by the costs associated with passive and active stomatal control.

Application of a two-pool model to soil carbon dynamics under elevated CO2.

Science.gov (United States)

van Groenigen, Kees Jan; Xia, Jianyang; Osenberg, Craig W; Luo, Yiqi; Hungate, Bruce A

2015-12-01

Elevated atmospheric CO2 concentrations increase plant productivity and affect soil microbial communities, with possible consequences for the turnover rate of soil carbon (C) pools and feedbacks to the atmosphere. In a previous analysis (Van Groenigen et al., 2014), we used experimental data to inform a one-pool model and showed that elevated CO2 increases the decomposition rate of soil organic C, negating the storage potential of soil. However, a two-pool soil model can potentially explain patterns of soil C dynamics without invoking effects of CO2 on decomposition rates. To address this issue, we refit our data to a two-pool soil C model. We found that CO2 enrichment increases decomposition rates of both fast and slow C pools. In addition, elevated CO2 decreased the carbon use efficiency of soil microbes (CUE), thereby further reducing soil C storage. These findings are consistent with numerous empirical studies and corroborate the results from our previous analysis. To facilitate understanding of C dynamics, we suggest that empirical and theoretical studies incorporate multiple soil C pools with potentially variable decomposition rates. © 2015 John Wiley & Sons Ltd.

ELEVATED CO2 AND ELEVATED TEMPERATURE HAVE NO EFFECT ON DOUGLAS-FIR FINE-ROOT DYNAMICS IN NITROGEN-POOR SOIL

Science.gov (United States)

Here, we investigate fine-root production, mortality and standing crop of Douglas-fir (Pseudotsuga menziesii) seedlings exposed to elevated atmospheric CO2 and elevated air temperature. We hypothesized that these treatments would increase fine-root production, but that mortality ...

Nitrogen-mediated effects of elevated CO2 on intra-aggregate soil pore structure.

Science.gov (United States)

Caplan, Joshua S; Giménez, Daniel; Subroy, Vandana; Heck, Richard J; Prior, Stephen A; Runion, G Brett; Torbert, H Allen

2017-04-01

Soil pore structure has a strong influence on water retention, and is itself influenced by plant and microbial dynamics such as root proliferation and microbial exudation. Although increased nitrogen (N) availability and elevated atmospheric CO 2 concentrations (eCO 2 ) often have interacting effects on root and microbial dynamics, it is unclear whether these biotic effects can translate into altered soil pore structure and water retention. This study was based on a long-term experiment (7 yr at the time of sampling) in which a C 4 pasture grass (Paspalum notatum) was grown on a sandy loam soil while provided factorial additions of N and CO 2 . Through an analysis of soil aggregate fractal properties supported by 3D microtomographic imagery, we found that N fertilization induced an increase in intra-aggregate porosity and a simultaneous shift toward greater accumulation of pore space in larger aggregates. These effects were enhanced by eCO 2 and yielded an increase in water retention at pressure potentials near the wilting point of plants. However, eCO 2 alone induced changes in the opposite direction, with larger aggregates containing less pore space than under control conditions, and water retention decreasing accordingly. Results on biotic factors further suggested that organic matter gains or losses induced the observed structural changes. Based on our results, we postulate that the pore structure of many mineral soils could undergo N-dependent changes as atmospheric CO 2 concentrations rise, having global-scale implications for water balance, carbon storage, and related rhizosphere functions. © 2016 John Wiley & Sons Ltd.

Effects of Elevated CO2 Concentration on the Biomasses and Nitrogen Concentrations in the Organs of Sainfoin(Onobrychis viciaefolia Scop.)

Institute of Scientific and Technical Information of China (English)

ZHOU Zheng-chao; SHANGGUAN Zhou-ping

2009-01-01

In forage grasses,the nitrogen concentration is directly related to the nutritional value.The studies examined the hypothesis that global elevation of CO2 concentration probably affects the biomass,nitrogen(N)concentration,and allocation and distribution patterns in the organs of forage grasses.While sainfoin(Onobrychis viciaefolia Scop.)seedlings grew on a low nutrient soil in closed chambers for 90 days,they were exposed to two CO2 concentrations(ambient or ambient+350μmol mol-1 CO2)without adding nutrients to them.After 90 days exposure to CO2,the biomasses of leaves,stems,and roots,and N concentrations and contents of different parts were measured.Compared with the ambient CO2 concentration,the elevated CO2 concentration increased the total dry matter by 25.07%,mainly due to the root and leaf having positive response to the elevated CO2 concentration.However,the elevated CO2 concentration did not change the proportions of the dry matters in different parts and the total plants compared with the ambient CO2 concentration.The elevated CO2 concentration lowered the N concentrations of the plant parts.Because the dry matter was higher,the elevated CO2 concentration had no effect on the N content in the plants compared to the ambient CO2 concentration.The elevated CO2 concentration promoted N allocations of the different parts significantly and increased N allocation of the underground part.The results have confirmed the previous suggestions that the elevated CO2 concentration stimulates plant biomass production and decreases the N concentrations of the plant parts.

Influences of soil volume and an elevated CO[sub 2] level on growth and CO[sub 2] exchange for the crassulacean acid metabolism plant Opuntia ficus-indica

Energy Technology Data Exchange (ETDEWEB)

Nobel, P.S.; Cui, M.; Miller, P.M.; Luo, Y. (UCLA-DOE Lab., Univ. of California, Los Angeles, CA (United States))

1994-01-01

Effects of the current (38 Pa) and an elevated (74 Pa) CO[sub 2] partial pressure on root and shoot areas, biomass accumulation and daily net CO[sub 2] exchange were determined for opuntia ficus-indica (L.) Miller, a highly productive Crassulacean acid metabolism species cultivated worldwide. Plants were grown in environmentally controlled rooms for 18 weeks in pots of three soil volumes (2600, 6500 and 26000 cm[sup 3]), the smallest of which was intended to restrict root growth. For plants in the medium-sized soil volume, basal cladodes tended to be thicker and areas of main and lateral roots tended to be greater as the CO[sub 2] level was doubled. Daughter cladodes tended to be initiated sooner at the current compared with the elevated CO[sub 2] level but total areas were similar by 10 weeks. At 10 weeks, daily net CO[sub 2] uptake for the three soil volumes averaged 24% higher for plants growing under elevated compared with current CO-2 levels, but at 18 weeks only 3% enhancement in uptake occurred. Dry weight gain was enhanced 24% by elevated CO[sub 2] during the first 10 weeks but only 8% over 18 weeks. Increasing the soil volume 10-fold led to a greater stimulation of daily net CO[sub 2] uptake and biomass production than did doubling the CO[sub 2] level. At 18 weeks, root biomass doubled and shoot biomass nearly doubled as the soil volume was increased 10-fold; the effects of soil volume tended to be greater for elevated CO[sub 2]. The amount of cladode nitrogen per unit dry weight decreased as the CO[sub 2] level was raised and increased as soil volume increased, the latter suggesting that the effects of soil volume could be due to nitrogen limitations. (au) (30 refs.)

Elevated CO2 increases photosynthesis in fluctuating irradiance regardless of photosynthetic induction state

NARCIS (Netherlands)

Kaiser, Elias; Zhou, Dianfan; Heuvelink, Ep; Harbinson, Jeremy; Morales Sierra, A.; Marcelis, Leo F.M.

2017-01-01

Leaves are often exposed to fluctuating irradiance, which limits assimilation. Elevated CO2 enhances dynamic photosynthesis (i.e. photosynthesis in fluctuating irradiance) beyond its effects on steady-state photosynthesis rates. Studying the role of CO2 in dynamic photosynthesis is important for

Lipoic acid and redox status in barley plants subjected to salinity and elevated CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Perez-Lopez, U.; Robredo, A.; Mena-Petite, A.; Munoz-Rueda, A. (Univ. del Pais Vasco/EHU, Dept. de Biologia Vegetal y Ecologia, Bilbao (Spain)); Lacuesta, M. (Univ. del Pais Vasco/EHU, Dept. de Biologia Vegetal y Ecologia, Vitoria-Gasteiz (Spain)); Sgherri, C.; Navari-Izzo, F. (Univ. di Pisa, Dipartimento di Chimica e Biotecnologie Agrarie, Pisa (Italy))

2010-02-15

Future environmental conditions will include elevated concentrations of salt in the soil and an elevated concentration of CO{sub 2}in the atmosphere. Because these environmental changes will likely affect reactive oxygen species (ROS) formation and cellular antioxidant metabolism in opposite ways, we analyzed changes in cellular H{sub 2}O{sub 2} and non-enzymatic antioxidant metabolite [lipoic acid (LA), ascorbate (ASA), glutathione (GSH)] content induced by salt stress (0, 80, 160 or 240 mM NaCl) under ambient (350 mumol mol-1) or elevated (700 mumol mol-1) CO{sub 2}concentrations in two barley cultivars (Hordeum vulgare L.) that differ in sensitivity to salinity (cv. Alpha is more sensitive than cv. Iranis). Under non-salinized conditions, elevated CO{sub 2}increased LA content, while ASA and GSH content decreased. Under salinized conditions and ambient CO{sub 2}, ASA increased, while GSH and LA decreased. At 240 mM NaCl, H{sub 2}O{sub 2} increased in Alpha and decreased in Iranis. When salt stress was imposed at elevated CO{sub 2}, less oxidative stress and lower increases in ASA were detected, while LA was constitutively higher. The decrease in oxidative stress could have been because of less ROS formation or to a higher constitutive LA level, which might have improved regulation of ASA and GSH reductions. Iranis had a greater capacity to synthesize ASA de novo and had higher constitutive LA content than did Alpha. Therefore, we conclude that elevated CO{sub 2}protects barley cultivars against oxidative damage. However, the magnitude of the positive effect is cultivar specific. (author)

Does elevated CO2 ameliorate the impact of O3 on chlorophyll content and photosynthesis in potato (Solanum tuberosum)?

Science.gov (United States)

Donnelly, Alison; Craigon, Jim; Black, Colin R.; Colls, Jeremy J.; Landon, Geoff

2001-04-01

This study examined the impact of season-long exposure to elevated carbon dioxide (CO2) and ozone (O3), individually and in combination, on leaf chlorophyll content and gas exchange characteristics in potato (Solanum tuberosum L. cv. Bintje). Plants grown in open-top chambers were exposed to three CO2 (ambient, 550 and 680 µmol mol-1) and two O3 treatments (ambient and elevated; 25 and 65 nmol mol-1, 8 h day-1 means, respectively) between crop emergence and maturity; plants were also grown in unchambered field plots. Non-destructive measurements of chlorophyll content and visible foliar injury were made for all treatments at 2-week intervals between 43 and 95 days after emergence. Gas exchange measurements were made for all except the intermediate 550 µmol mol-1 CO2 treatment. Season-long exposure to elevated O3 under ambient CO2 reduced chlorophyll content and induced extensive visible foliar damage, but had little effect on net assimilation rate or stomatal conductance. Elevated CO2 had no significant effect on chlorophyll content, but greatly reduced the damaging impact of O3 on chlorophyll content and visible foliar damage. Light-saturated assimilation rates for leaves grown under elevated CO2 were consistently lower when measured under either elevated or ambient CO2 than in equivalent leaves grown under ambient CO2. Analysis of CO2 response curves revealed that CO2-saturated assimilation rate, maximum rates of carboxylation and electron transport and respiration decreased with time. CO2-saturated assimilation rate was reduced by elevated O3 during the early stages of the season, while respiration was significantly greater under elevated CO2 as the crop approached maturity. The physiological origins of these responses and their implications for the performance of potato in a changing climate are discussed.

Changes in concentration and (delta) 13C value of dissolved CH4, CO2 and organic carbon in rice paddies under ambient and elevated concentrations of atmospheric CO2

International Nuclear Information System (INIS)

Weiguo Cheng; Yagi, Kazuyuki; Sakai, Hidemitsu; Hua Xu; Kobayashi, Kazuhiko

2005-01-01

Changes in concentration and (delta) 13 C value of dissolved CH 4 , CO 2 and organic carbon (DOC) in floodwater and soil solution from a Japanese rice paddy were studied under ambient and elevated concentrations of atmospheric CO 2 in controlled environment chambers. The concentrations of dissolved CH 4 in floodwater increased with rice growth (with some fluctuation), while the concentrations of CO 2 remained between 2.9 to 4.4 and 4.2 to 5.8 μg C mL -1 under conditions of ambient and elevated CO 2 concentration, respectively. The amount of CH 4 dissolved in soil solution under elevated CO 2 levels was significantly lower than under ambient CO 2 in the tillering stage, implying that the elevated CO 2 treatment accelerated CH 4 oxidation during the early stage of growth. However, during later stages of growth, production of CH 4 increased and the amount of CH 4 dissolved in soil solution under elevated CO 2 levels was, on average, greater than that under ambient CO 2 conditions. Significant correlation existed among the (delta) 13 C values of dissolved CH 4 , CO 2 , and DOC in floodwater (except for the samples taken immediately after pulse feeding with 13 C enriched CO 2 ), indicating that the origins and cycling of CH 4 , CO 2 and DOC were related. There were also significant correlations among the (delta) 13 C values of CH 4 , CO 2 and DOC in the soil solution. The turnover rate of CO 2 in soil solution was most rapid in the panicle formation stage of rice growth and that of CH 4 fastest in the grain filling stage. (Author)

Response of archaeal communities in the rhizosphere of maize and soybean to elevated atmospheric CO2 concentrations.

Directory of Open Access Journals (Sweden)

David M Nelson

Full Text Available BACKGROUND: Archaea are important to the carbon and nitrogen cycles, but it remains uncertain how rising atmospheric carbon dioxide concentrations ([CO(2] will influence the structure and function of soil archaeal communities. METHODOLOGY/PRINCIPAL FINDINGS: We measured abundances of archaeal and bacterial 16S rRNA and amoA genes, phylogenies of archaeal 16S rRNA and amoA genes, concentrations of KCl-extractable soil ammonium and nitrite, and potential ammonia oxidation rates in rhizosphere soil samples from maize and soybean exposed to ambient (∼385 ppm and elevated (550 ppm [CO(2] in a replicated and field-based study. There was no influence of elevated [CO(2] on copy numbers of archaeal or bacterial 16S rRNA or amoA genes, archaeal community composition, KCl-extractable soil ammonium or nitrite, or potential ammonia oxidation rates for samples from maize, a model C(4 plant. Phylogenetic evidence indicated decreased relative abundance of crenarchaeal sequences in the rhizosphere of soybean, a model leguminous-C(3 plant, at elevated [CO(2], whereas quantitative PCR data indicated no changes in the absolute abundance of archaea. There were no changes in potential ammonia oxidation rates at elevated [CO(2] for soybean. Ammonia oxidation rates were lower in the rhizosphere of maize than soybean, likely because of lower soil pH and/or abundance of archaea. KCl-extractable ammonium and nitrite concentrations were lower at elevated than ambient [CO(2] for soybean. CONCLUSION: Plant-driven shifts in soil biogeochemical processes in response to elevated [CO(2] affected archaeal community composition, but not copy numbers of archaeal genes, in the rhizosphere of soybean. The lack of a treatment effect for maize is consistent with the fact that the photosynthesis and productivity of maize are not stimulated by elevated [CO(2] in the absence of drought.

Rising CO2 interacts with growth light and growth rate to alter photosystem II photoinactivation of the coastal diatom Thalassiosira pseudonana.

Directory of Open Access Journals (Sweden)

Gang Li

Full Text Available We studied the interactive effects of pCO(2 and growth light on the coastal marine diatom Thalassiosira pseudonana CCMP 1335 growing under ambient and expected end-of-the-century pCO(2 (750 ppmv, and a range of growth light from 30 to 380 µmol photons·m(-2·s(-1. Elevated pCO(2 significantly stimulated the growth of T. pseudonana under sub-saturating growth light, but not under saturating to super-saturating growth light. Under ambient pCO(2 susceptibility to photoinactivation of photosystem II (σ(i increased with increasing growth rate, but cells growing under elevated pCO(2 showed no dependence between growth rate and σ(i, so under high growth light cells under elevated pCO(2 were less susceptible to photoinactivation of photosystem II, and thus incurred a lower running cost to maintain photosystem II function. Growth light altered the contents of RbcL (RUBISCO and PsaC (PSI protein subunits, and the ratios among the subunits, but there were only limited effects on these and other protein pools between cells grown under ambient and elevated pCO(2.

Dryland biological soil crust cyanobacteria show unexpected decreases in abundance under long-term elevated CO2

Science.gov (United States)

Steven, Blaire; Gallegos-Graves, La Verne; Yeager, Chris M.; Belnap, Jayne; Evans, R. David; Kuske, Cheryl R.

2012-01-01

Biological soil crusts (biocrusts) cover soil surfaces in many drylands globally. The impacts of 10 years of elevated atmospheric CO2 on the cyanobacteria in biocrusts of an arid shrubland were examined at a large manipulated experiment in Nevada, USA. Cyanobacteria-specific quantitative PCR surveys of cyanobacteria small-subunit (SSU) rRNA genes suggested a reduction in biocrust cyanobacterial biomass in the elevated CO2 treatment relative to the ambient controls. Additionally, SSU rRNA gene libraries and shotgun metagenomes showed reduced representation of cyanobacteria in the total microbial community. Taxonomic composition of the cyanobacteria was similar under ambient and elevated CO2 conditions, indicating the decline was manifest across multiple cyanobacterial lineages. Recruitment of cyanobacteria sequences from replicate shotgun metagenomes to cyanobacterial genomes representing major biocrust orders also suggested decreased abundance of cyanobacteria sequences across the majority of genomes tested. Functional assignment of cyanobacteria-related shotgun metagenome sequences indicated that four subsystem categories, three related to oxidative stress, were differentially abundant in relation to the elevated CO2 treatment. Taken together, these results suggest that elevated CO2 affected a generalized decrease in cyanobacteria in the biocrusts and may have favoured cyanobacteria with altered gene inventories for coping with oxidative stress.

Elevated CO{sub 2} and ozone reduce nitrogen acquisition by Pinus halepensis from its mycorrhizal symbiont

Energy Technology Data Exchange (ETDEWEB)

Kytoeviita, M.M. [Oulu Univ., Dept. of Biology, Oulu (Finland); Thiec, D. Le [Univ. Henri Poincare-Nancy, Lab. de Biologie Forestiere, Vandoeuvre-les-Nancy (France); Dizengremel, P. [Unite Ecophysiologie Forestiere-Lab. de Pollution Atmospherique, INRA-Centre de Recherches Forestieres, Champenoux (France)

2001-07-01

The effects of 700 {mu}mol mol{sup -1} CO{sub 2} and 200 nmol mol{sup -1} ozone on photosynthesis in Pinus halepensis seedlings and on N translocation from its mycorrhizal symbiont, Paxillus involutus, were studied under nutrient-poor conditions. After 79 days of exposure, ozone reduced and elevated CO{sub 2} increased net assimilation rate. However, the effect was dependent on daily accumulated exposure. No statistically significant differences in total plant mass accumulation were observed, although ozone-treated plants tended to be smaller. Changes in atmospheric gas concentrations induced changes in allocation of resources: under elevated ozone, shoots showed high priority over roots and had significantly elevated N concentrations. As a result of different shoot N concentration and net carbon assimilation rates, photosynthetic N use efficiency was significantly increased under elevated CO{sub 2} and decreased under ozone. The differences in photosynthesis were mirrored in the growth of the fungus in symbiosis with the pine seedlings. However, exposure to CO{sub 2} and ozone both reduced the symbiosis-mediated N uptake. The results suggest an increased carbon cost of symbiosis-mediated N uptake under elevated CO{sub 2} while under ozone, plant N acquisition is preferentially shifted towards increased root uptake. (au)

Element Pool Changes within a Scrub-Oak Ecosystem after 11 Years of Exposure to Elevated CO2

Science.gov (United States)

Duval, Benjamin D.; Dijkstra, Paul; Drake, Bert G.; Johnson, Dale W.; Ketterer, Michael E.; Megonigal, J. Patrick; Hungate, Bruce A.

2013-01-01

The effects of elevated CO2 on ecosystem element stocks are equivocal, in part because cumulative effects of CO2 on element pools are difficult to detect. We conducted a complete above and belowground inventory of non-nitrogen macro- and micronutrient stocks in a subtropical woodland exposed to twice-ambient CO2 concentrations for 11 years. We analyzed a suite of nutrient elements and metals important for nutrient cycling in soils to a depth of ∼2 m, in leaves and stems of the dominant oaks, in fine and coarse roots, and in litter. In conjunction with large biomass stimulation, elevated CO2 increased oak stem stocks of Na, Mg, P, K, V, Zn and Mo, and the aboveground pool of K and S. Elevated CO2 increased root pools of most elements, except Zn. CO2-stimulation of plant Ca was larger than the decline in the extractable Ca pool in soils, whereas for other elements, increased plant uptake matched the decline in the extractable pool in soil. We conclude that elevated CO2 caused a net transfer of a subset of nutrients from soil to plants, suggesting that ecosystems with a positive plant growth response under high CO2 will likely cause mobilization of elements from soil pools to plant biomass. PMID:23717607

Root growth and N dynamics in response to multi-year experimental warming, summer drought and elevated CO2 in a mixed heathland-grass ecosystem

DEFF Research Database (Denmark)

Arndal, M. F.; Schmidt, I. K.; Kongstad, J.

2013-01-01

growth would be matched by an increase in root nutrient uptake of NH4+-N and NO3- -N. Root growth was significantly increased by elevated CO2. The roots, however, did not fully compensate for the higher growth with a similar increase in nitrogen uptake per unit of root mass. Hence the nitrogen...... concentration in roots was decreased in elevated CO2, whereas the biomass N pool was unchanged or even increased. The higher net root production in elevated CO2 might be a strategy for the plants to cope with increased nutrient demand leading to a long-term increase in N uptake on a whole-plant basis. Drought...... reduced grass root biomass and N uptake, especially when combined with warming, but CO2 was the most pronounced main factor effect. Several significant interactions of the treatments were found, which indicates that the responses were nonadditive and that changes to multiple environmental changes cannot...

Stomatal response of Pinus sylvestriformis to elevated CO2 concentrations during the four years of exposure

Institute of Scientific and Technical Information of China (English)

ZHOU Yu-mei; HAN Shi-jie; LIU Ying; JIA Xia

2005-01-01

Four-year-old Pinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol-1) and high CO2 concentrations (500 and 700 μmol·mol-1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China (42oN, 128oE). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (gs), ratio of intercellular to ambient CO2 concentration (ci/ca) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol-1 CO2 grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol-1CO2). High-[CO2]-grown plants exhibited lower ci/ca ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However, ci/ca ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation pattern of stomata between upper and lower surface of needle.

Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

Science.gov (United States)

Wang, X; Lewis, J D; Tissue, D T; Seemann, J R; Griffin, K L

2001-02-27

Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measured as the rate of CO(2) efflux at zero light. Leaf R(L) and R(D) were significantly higher at elevated than at ambient CO(2) throughout the growing period. Elevated CO(2) increased the ratio of leaf R(L) to net photosynthesis at saturated light (A(max)) when plants were young and also after flowering, but the ratio of leaf R(D) to A(max) was unaffected by CO(2) levels. Leaf R(N) was significantly higher at the beginning but significantly lower at the end of the growing period in elevated CO(2)-grown plants. The ratio of leaf R(L) to R(D) was used to estimate the effect of light on leaf R during the day. We found that light inhibited leaf R at both CO(2) concentrations but to a lesser degree for elevated (17-24%) than for ambient (29-35%) CO(2)-grown plants, presumably because elevated CO(2)-grown plants had a higher demand for energy and carbon skeletons than ambient CO(2)-grown plants in light. Our results suggest that using the CO(2) efflux rate, determined by shading leaves during the day, as a measure for leaf R is likely to underestimate carbon loss from elevated CO(2)-grown plants.

Sensitive indicators of Stipa bungeana response to precipitation under ambient and elevated CO2 concentration

Science.gov (United States)

Shi, Yaohui; Zhou, Guangsheng; Jiang, Yanling; Wang, Hui; Xu, Zhenzhu

2018-02-01

Precipitation is a primary environmental factor in the semiarid grasslands of northern China. With increased concentrations of atmospheric greenhouse gases, precipitation regimes will change, and high-impact weather events may be more common. Currently, many ecophysiological indicators are known to reflect drought conditions, but these indicators vary greatly among species, and few studies focus on the applicability of these drought indicators under high CO2 conditions. In this study, five precipitation levels (- 30%, - 15%, control, + 15%, and + 30%) were used to simulate the effects of precipitation change on 18 ecophysiological characteristics in Stipa bungeana, including leaf area, plant height, leaf nitrogen (N), and chlorophyll content, among others. Two levels of CO2 concentration (ambient, 390 ppm; 550 ppm) were used to simulate the effects of elevated CO2 on these drought indicators. Using gray relational analysis and phenotypic plasticity analysis, we found that total leaf area or leaf number (morphology), leaf water potential or leaf water content (physiology), and aboveground biomass better reflected the water status of S. bungeana under ambient and elevated CO2 than the 13 other analyzed variables. The sensitivity of drought indicators changed under the elevated CO2 condition. By quantifying the relationship between precipitation and the five most sensitive indicators, we found that the thresholds of precipitation decreased under elevated CO2 concentration. These results will be useful for objective monitoring and assessment of the occurrence and development of drought events in S. bungeana grasslands.

Cycling-induced degradation of LiCoO{sub 2} thin-film cathodes at elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Van Sluytman, J.S.; Alamgir, F.M.; Greenbaum, S.G. [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10021 (United States); West, W.C.; Whitacre, J.F. [Electrochemical Technologies Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2006-04-01

The cycle life of LiCoO{sub 2}-based all solid-state thin-film cells has been studied at room temperature, and at elevated temperatures of 50, 100, and 150{sup o}C. X-ray diffraction, as well as Raman analysis, has been used to complement the electrochemical data in examining structural and chemical changes. XRD and Raman spectroscopy data indicate that elevated temperature soaks of the thin-film batteries in the quiescent state causes no discernible changes in the LiCoO{sub 2} cathode layer. However, when the thin-film batteries are cycled at elevated temperatures, decreases in average grain size of the LiCoO{sub 2} film occur with dramatic concomitant charge and discharge capacity loss. (author)

Evaluation of CO2-Fluid-Rock Interaction in Enhanced Geothermal Systems: Field-Scale Geochemical Simulations

Directory of Open Access Journals (Sweden)

Feng Pan

2017-01-01

Full Text Available Recent studies suggest that using supercritical CO2 (scCO2 instead of water as a heat transmission fluid in Enhanced Geothermal Systems (EGS may improve energy extraction. While CO2-fluid-rock interactions at “typical” temperatures and pressures of subsurface reservoirs are fairly well known, such understanding for the elevated conditions of EGS is relatively unresolved. Geochemical impacts of CO2 as a working fluid (“CO2-EGS” compared to those for water as a working fluid (H2O-EGS are needed. The primary objectives of this study are (1 constraining geochemical processes associated with CO2-fluid-rock interactions under the high pressures and temperatures of a typical CO2-EGS site and (2 comparing geochemical impacts of CO2-EGS to geochemical impacts of H2O-EGS. The St. John’s Dome CO2-EGS research site in Arizona was adopted as a case study. A 3D model of the site was developed. Net heat extraction and mass flow production rates for CO2-EGS were larger compared to H2O-EGS, suggesting that using scCO2 as a working fluid may enhance EGS heat extraction. More aqueous CO2 accumulates within upper- and lower-lying layers than in the injection/production layers, reducing pH values and leading to increased dissolution and precipitation of minerals in those upper and lower layers. Dissolution of oligoclase for water as a working fluid shows smaller magnitude in rates and different distributions in profile than those for scCO2 as a working fluid. It indicates that geochemical processes of scCO2-rock interaction have significant effects on mineral dissolution and precipitation in magnitudes and distributions.

CO/sub 2/ carbon cycle and climate interactions

Energy Technology Data Exchange (ETDEWEB)

Grassl, H; Maier-Reimer, E; Degens, E T; Kempe, S; Spitzy, A

1984-03-01

Past and expected emissions of anthropogenic CO/sub 2/ stimulate carbon cycle and climate research. Prognoses of future CO/sub 2/ levels depend on energy scenarios and on the reaction of the biosphere and hydrosphere to elevated atmospheric CO/sub 2/ concentrations. The reaction of the reservoirs vegetation, freshwater and oceans to disturbances of the carbon cycle is reviewed. For the oceans first results of a simple carbon cycle model implanted in a three-dimensional general circulation model are presented. This model allows experiments not possible with previous box models.

Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open-air CO2 elevation in rice.

Science.gov (United States)

Shimono, Hiroyuki; Nakamura, Hirofumi; Hasegawa, Toshihiro; Okada, Masumi

2013-08-01

An elevated atmospheric CO2 concentration ([CO2 ]) can reduce stomatal conductance of leaves for most plant species, including rice (Oryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [CO2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open-air CO2 elevation. Stomatal conductance decreased by 27% under elevated [CO2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [CO2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor-pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m(2)  m(-2) , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [CO2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [CO2 ] and 1.17 at elevated [CO2 ]. This study provides the first direct measurement of the effects of elevated [CO2 ] on rice canopy evapotranspiration under open-air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields. © 2013 John Wiley & Sons Ltd.

CO2, Temperature, and Soil Moisture Interactions Affect NDVI and Reproductive Phenology in Old-Field Plant Communities

Science.gov (United States)

Engel, C.; Weltzin, J.; Norby, R.

2004-12-01

Plant community composition and ecosystem function may be altered by global atmospheric and climate change, including increased atmospheric [CO2], temperature, and varying precipitation regimes. We are conducting an experiment at Oak Ridge National Laboratory (ORNL) utilizing open-top chambers to administer experimental treatments of elevated CO2 (+300 ppm), warming (+ 3 degrees Celsius), and varying soil moisture availability to experimental plant communities constructed of seven common old-field species, including C3 and C4 grasses, forbs, and legumes. During 2004 we monitored plant community phenology (NDVI) and plant reproductive phenology. Early in the year, NDVI was greater in wet treatment plots, and was unaffected by main effects of temperature or CO2. This result suggests that early in the season warming is insufficient to affect early canopy development. Differences in soil moisture sustained throughout the winter and into early spring may constitute an important control on early canopy greenup. Elevated CO2 alleviated detrimental effects of warming on NDVI, but only early in the season. As ambient temperatures increased, elevated temperatures negatively impacted NDVI only in the dry plots. Wetter conditions ameliorate the effects of warming on canopy greenness during the warmer seasons of the year. Warming increased rates of bolting, number of inflorescences, and time to reproductive maturity for Andropogon virginicus (a C4 bunchgrass). Solidago Canadensis (a C3 late-season forb) also produced flowers earlier in elevated temperatures. Conversely, none of the C3 grasses and forbs that bolt or flower in late spring or early summer responded to temperature or CO2. Results indicate that warming and drought may impact plant community phenology, and plant species reproductive phenology. Clearly community phenology is driven by complex interactions among temperature, water, and CO2 that change throughout the season. Our data stresses the importance of

Co[sub 2] exchange, environmental productivity indices, and productivity of opuntia ficus-indica under current and elevated CO[sub 2] concentrations

Energy Technology Data Exchange (ETDEWEB)

Nobel, P.S.

1992-01-01

This project involved placing mature cladodes (flattened stem segments) of Opuntia ficus-indica in growth chambers containing 360 or 720 ppM CO[sub 2]. After nine weeks, the new daughter cladodes initiated on the planted cladodes averaged 7% higher in biomass but 8% less is area, leading to a specific stem mass for this Crassulacean acid metabolism (CAM) species that was 16% higher under the elevated CO[sub 2] condition. This is similar to be less dramatic than the increase in specific leaf mass for C[sub 3] and C[sub 4] plants under elevated CO[sub 2], which generally ranges from 28% to 40%. Another contrast with C[sub 3] and C[sub 4] Plants was the reliance of the new organs of the CAM plant on biomass translocated from existing organs instead of derived directly from current photosynthate. In this regard, 18% less dry weight was translocated from basal cladodes into daughter cladodes of Q. ficus-indica at 720 ppM CO[sub 2] compared with 360 ppM.

Responses of soil microbial activity to cadmium pollution and elevated CO2.

Science.gov (United States)

Chen, Yi Ping; Liu, Qiang; Liu, Yong Jun; Jia, Feng An; He, Xin Hua

2014-03-06

To address the combined effects of cadmium (Cd) and elevated CO2 on soil microbial communities, DGGE (denaturing gradient gel electrophoresis) profiles, respiration, carbon (C) and nitrogen (N) concentrations, loessial soils were exposed to four levels of Cd, i.e., 0 (Cd0), 1.5 (Cd1.5), 3.0 (Cd3.0) and 6.0 (Cd6.0) mg Cd kg(-1) soil, and two levels of CO2, i.e., 360 (aCO2) and 480 (eCO2) ppm. Compared to Cd0, Cd1.5 increased fungal abundance but decreased bacterial abundance under both CO2 levels, whilst Cd3.0 and Cd6.0 decreased both fungal and bacterial abundance. Profiles of DGGE revealed alteration of soil microbial communities under eCO2. Soil respiration decreased with Cd concentrations and was greater under eCO2 than under aCO2. Soil total C and N were greater under higher Cd. These results suggest eCO2 could stimulate, while Cd pollution could restrain microbial reproduction and C decomposition with the restraint effect alleviated by eCO2.

The impact of elevated CO2 concentration on the Rubisco activity

Czech Academy of Sciences Publication Activity Database

Hrstka, M.; Urban, Otmar; Nečesaná, P.

2002-01-01

Roč. 96, - (2002), s. 121-123 ISSN 0009-2770. [2nd Meeting of Chemistry and Life . Brno, 10.10.2002-11.10.2002] Institutional research plan: CEZ:AV0Z6087904 Keywords : elevated CO2 * Norway spruce * Rubisco Subject RIV: ED - Physiology Impact factor: 0.336, year: 2002

Effects of long-term elevated atmospheric CO{sub 2} concentrations on Pinus ponderosa

Energy Technology Data Exchange (ETDEWEB)

Surano, K.A.; Kercher, J.R. [eds.

1993-10-01

This report details the results from an experiment of the effects of long-term elevated atmospheric CO{sub 2} concentrations on ponderosa pine (Pinus ponderosa Laws.) saplings and seedlings. The study began in 1983 as a pilot study designed to explore the feasibility of using open-top chambers for continuous multi-year exposures on sapling-sized trees and to examine possible CO{sub 2} responses so that future research could be adequately designed. however, following the first year of exposure, preliminary results from the study indicated that measurements of CO{sub 2} responses should be intensified. Open-top chambers proved suitable for use in multiyear exposures of mature trees. With respect to the preliminary examination of CO{sub 2} responses, many interesting observations were made. The nature of the preliminary results suggests that future long-term field CO{sub 2} exposures on perennial species may be critical to the understanding and preparation for future environments. Other research reported here attempted to adapt an existing western coniferous forest growth and succession model for use in elevated CO{sub 2} scenarios using differential species responses, and assessed the usefulness of the model in that regard. Seven papers have been processed separately for inclusion in the appropriate data bases.

Effect of elevated atmospheric CO/sub 2/on nitrogen distribution and N utilization efficiency in winter rape (brassica napus L.)

International Nuclear Information System (INIS)

Zhang, Z. H.; Lu, S.; Wang, W. M.; Song, H. X.; Lepo, J. E.

2017-01-01

We characterized the responses of plant dry biomass, nitrogen (N) distribution and N-utilization efficiency (NUtE) to changes in CO/sub 2/ concentration through exposure and culture of winter rape under normal-(380 mu mol.mol/sup -1/) and elevated-CO/sub 2/ (760 mu mo mol/sup -1/) conditions. Brassica napus (Xiangyou 15) was used as an agriculturally important model plant. Plants were cultivated in a greenhouse with sand culture under normal- (15 mmol.L/sup -1/) and limited-N (5 mmol.L/sup -1/) conditions. NUtE increased with elevated CO/sub 2/ regardless of whether N was limited. NUtE was higher under N limitation than under normal N conditions for both normal- and elevated-CO/sub 2/ conditions. 15N labeling was used to assess the distribution of N from vegetative- to reproductive-organs.N distribution within the plant and during different developmental stages was affected by CO/sub 2/ concentration and the level of N application. A higher proportion of N was found in siliques at the harvest stage for N-limited plants compared to normal-N plants. The proportion of N absorbed into siliques after the stem elongation stage under elevated-CO/sub 2/ conditions was significantly higher than under normal CO/sub 2/. The proportion of N transport, as well as the total amount of N, absorbed at the stem elongation stage from vegetative organs into siliques under elevated CO/sub 2/ was significantly lower than under normal-CO/sub 2/ conditions. However, the proportion of N absorbed at the stem elongation stage and thus lost from the silique under elevated CO/sub 2/ was significantly higher than under normal CO/sub 2/. In conclusion, limited N or elevated CO/sub 2/ generally benefitted plant NUtE. In addition, after the stem elongation stage, elevated CO/sub 2/ promoted the redistribution of N from plant vegetative tissues to reproductive organs; however, elevated CO/sub 2/ during or before stem elongation had the opposite effect. (author)

The effect of elevated CO2 on the vegetative and generative growth of Phalaenopsis

OpenAIRE

Kromwijk, J.A.M.; Meinen, E.; Dueck, T.A.

2014-01-01

Phalaenopsis is a crassulacean acid metabolism (CAM) plant which absorbs and binds CO2 as malate during the night. During daytime the stomata close and the CO2 stored in the vacuole is released and used for photosynthesis. Because the CO2 taken up by CAM plants was assumed to be unaffected by the CO2 concentration in the air, additional CO2 for increased growth was generally not supplied in Phalaenopsis. However, a literature study indicated that elevated CO2 might have a positive effect in P...

Elevated [CO2] modified the drought acclimation response in peanut

Science.gov (United States)

Peanut agroecosystems play a key role in food production and are a major source of protein in many arid and semi-arid regions where extreme weather events are expected to increase in frequency. We are taking a systems-level approach to investigate the response of peanut to elevated [CO2], water defi...

Maintenance of C sinks sustains enhanced C assimilation during long-term exposure to elevated [CO2] in Mojave Desert shrubs.

Science.gov (United States)

Aranjuelo, Iker; Ebbets, Allison L; Evans, R Dave; Tissue, David T; Nogués, Salvador; van Gestel, Natasja; Payton, Paxton; Ebbert, Volker; Adams, Williams W; Nowak, Robert S; Smith, Stanley D

2011-10-01

During the first few years of elevated atmospheric [CO(2)] treatment at the Nevada Desert FACE Facility, photosynthetic downregulation was observed in desert shrubs grown under elevated [CO(2)], especially under relatively wet environmental conditions. Nonetheless, those plants maintained increased A (sat) (photosynthetic performance at saturating light and treatment [CO(2)]) under wet conditions, but to a much lesser extent under dry conditions. To determine if plants continued to downregulate during long-term exposure to elevated [CO(2)], responses of photosynthesis to elevated [CO(2)] were examined in two dominant Mojave Desert shrubs, the evergreen Larrea tridentata and the drought-deciduous Ambrosia dumosa, during the eighth full growing season of elevated [CO(2)] treatment at the NDFF. A comprehensive suite of physiological processes were collected. Furthermore, we used C labeling of air to assess carbon allocation and partitioning as measures of C sink activity. Results show that elevated [CO(2)] enhanced photosynthetic performance and plant water status in Larrea, especially during periods of environmental stress, but not in Ambrosia. δ(13)C analyses indicate that Larrea under elevated [CO(2)] allocated a greater proportion of newly assimilated C to C sinks than Ambrosia. Maintenance by Larrea of C sinks during the dry season partially explained the reduced [CO(2)] effect on leaf carbohydrate content during summer, which in turn lessened carbohydrate build-up and feedback inhibition of photosynthesis. δ(13)C results also showed that in a year when plant growth reached the highest rates in 5 years, 4% (Larrea) and 7% (Ambrosia) of C in newly emerging organs were remobilized from C that was assimilated and stored for at least 2 years prior to the current study. Thus, after 8 years of continuous exposure to elevated [CO(2)], both desert perennials maintained their photosynthetic capacities under elevated [CO(2)]. We conclude that C storage, remobilization

Defoliation reduces soil biota - and modifies stimulating effects of elevated CO₂

DEFF Research Database (Denmark)

Dam, Marie; Christensen, Søren

2015-01-01

defoliation increased activity and biomass of soil biota and more so at elevated CO2. Based on soil biota responses, plants defoliated in active growth therefore conserve resources, whereas defoliation after termination of growth results in release of resources. This result challenges the idea that plants via...... was needed to reduce nematodes. We found positive effects of CO2 on root density and microbial biomass. Defoliation affected soil biota negatively, whereas elevated CO2 stimulated the plant-soil system. This effect seen in June is contrasted by the effects seen in September at the same site. Late season...... assessed in the rhizosphere of manually defoliated patches of Deschampsia flexuosa in June in a full-factorial FACE experiment with the treatments: increased atmospheric CO2, increased nighttime temperatures, summer droughts, and all of their combinations. We found a negative effect of defoliation...

Elevated CO_2 levels increase the toxicity of ZnO nanoparticles to goldfish (Carassius auratus) in a water-sediment ecosystem

International Nuclear Information System (INIS)

Yin, Ying; Hu, Zhengxue; Du, Wenchao; Ai, Fuxun; Ji, Rong; Gardea-Torresdey, Jorge L.; Guo, Hongyan

2017-01-01

Highlights: • Elevated CO_2 increased the Zn content in suspension by reducing pH value. • Elevated CO_2 led to higher Zn accumulation in fish tissues. • Elevated CO_2 also intensified the oxidative damage to fish induced by nZnO. - Abstract: Concerns about the environmental safety of metal-based nanoparticles (MNPs) in aquatic ecosystems are increasing. Simultaneously, elevated atmospheric CO_2 levels are a serious problem worldwide, making it possible for the combined exposure of MNPs and elevated CO_2 to the ecosystem. Here we studied the toxicity of nZnO to goldfish in a water-sediment ecosystem using open-top chambers flushed with ambient (400 ± 10 μL/L) or elevated (600 ± 10 μL/L) CO_2 for 30 days. We measured the content of Zn in suspension and fish, and analyzed physiological and biochemical changes in fish tissues. Results showed that elevated CO_2 increased the Zn content in suspension by reducing the pH value of water and consequently enhanced the bioavailability and toxicity of nZnO. Elevated CO_2 led to higher accumulation of Zn in fish tissues (increased by 43.3%, 86.4% and 22.5% in liver, brain and muscle, respectively) when compared to ambient. Elevated CO_2 also intensified the oxidative damage to fish induced by nZnO, resulting in higher ROS intensity, greater contents of MDA and MT and lower GSH content in liver and brain. Our results suggest that more studies in natural ecosystems are needed to better understand the fate and toxicity of nanoparticles in future CO_2 levels.

Soil respiration in relation to photosynthesis of Quercus mongolica trees at elevated CO2.

Science.gov (United States)

Zhou, Yumei; Li, Mai-He; Cheng, Xu-Bing; Wang, Cun-Guo; Fan, A-Nan; Shi, Lian-Xuan; Wang, Xiu-Xiu; Han, Shijie

2010-12-06

Knowledge of soil respiration and photosynthesis under elevated CO(2) is crucial for exactly understanding and predicting the carbon balance in forest ecosystems in a rapid CO(2)-enriched world. Quercus mongolica Fischer ex Ledebour seedlings were planted in open-top chambers exposed to elevated CO(2) (EC = 500 µmol mol(-1)) and ambient CO(2) (AC = 370 µmol mol(-1)) from 2005 to 2008. Daily, seasonal and inter-annual variations in soil respiration and photosynthetic assimilation were measured during 2007 and 2008 growing seasons. EC significantly stimulated the daytime soil respiration by 24.5% (322.4 at EC vs. 259.0 mg CO(2) m(-2) hr(-1) at AC) in 2007 and 21.0% (281.2 at EC vs. 232.6 mg CO(2) m(-2) hr(-1) at AC) in 2008, and increased the daytime CO(2) assimilation by 28.8% (624.1 at EC vs. 484.6 mg CO(2) m(-2) hr(-1) at AC) across the two growing seasons. The temporal variation in soil respiration was positively correlated with the aboveground photosynthesis, soil temperature, and soil water content at both EC and AC. EC did not affect the temperature sensitivity of soil respiration. The increased daytime soil respiration at EC resulted mainly from the increased aboveground photosynthesis. The present study indicates that increases in CO(2) fixation of plants in a CO(2)-rich world will rapidly return to the atmosphere by increased soil respiration.

CO[sub 2] exchange and growth of the Crassulacean acid metabolism plant opuntia ficus-indica under elevated CO[sub 2] in open-top chambers

Energy Technology Data Exchange (ETDEWEB)

Cui, M.; Miller, P.M.; Nobel, P.S. (Univ. of California, Los Angeles, CA (United States))

1993-10-01

CO[sub 2] uptake, water vapor conductance, and biomass production of Opuntia ficus-indica, a Crassulacean acid metabolism species, were studied at CO[sub 2] concentrations of 370, 520, and 720 [mu]L L[sup [minus]1] in open-top chambers during a 23-week period. Nine weeks after planting, daily net CO[sub 2] uptake for basal cladodes at 520 and 720 [mu]L L[sup [minus]1] of CO[sub 2] was 76 and 98% higher, respectively, than at 370 [mu]L L[sup [minus]1]. Eight weeks after daughter cladodes emerged, their daily net CO[sub 2] uptake was 35 and 49% higher at 520 and 720 [mu]L L[sup [minus]1] of CO[sub 2], respectively, than at 370 L L[sup [minus]1]. Daily water-use efficiency was 88% higher under elevated CO[sub 2] for basal cladodes and 57% higher for daughter cladodes. The daily net CO[sub 2] uptake capacity for basal cladodes increased for 4 weeks after planting and then remained fairly constant, whereas for daughter cladodes, it increased with cladode age, became maximal at 8 to 14 weeks, and then declined. The percentage enhancement in daily net CO[sub 2] uptake caused by elevated CO[sub 2] was greatest initially for basal cladodes and at 8 to 14 weeks for daughter cladodes. The chlorophyll content per unit fresh weight of chlorenchyma for daughter cladodes at 8 weeks was 19 and 62% lower in 520 and 720 [mu]L L[sup [minus]1] of CO[sub 2], respectively, compared with 370 [mu]L L[sup [minus]1]. Despite the reduced chlorophyll content, plant biomass production during 23 weeks in 520 and 720 [mu]L L[sup [minus]1] of CO[sub 2] was 21 and 55% higher, respectively, than at 370 [mu]L L[sup [minus]1]. The root dry weight nearly tripled as the CO[sub 2] concentration was doubled, causing the root/shoot ratio to increase with CO[sub 2] concentration. During the 23-week period, elevated CO[sub 2] significantly increased CO[sub 2] uptake and biomass production of O. 35 refs., 4 figs., 1 tab.

Spring photosynthetic recovery of boreal Norway spruce under conditions of elevated [CO(2)] and air temperature.

Science.gov (United States)

Wallin, Göran; Hall, Marianne; Slaney, Michelle; Räntfors, Mats; Medhurst, Jane; Linder, Sune

2013-11-01

Accumulated carbon uptake, apparent quantum yield (AQY) and light-saturated net CO2 assimilation (Asat) were used to assess the responses of photosynthesis to environmental conditions during spring for three consecutive years. Whole-tree chambers were used to expose 40-year-old field-grown Norway spruce trees in northern Sweden to an elevated atmospheric CO2 concentration, [CO2], of 700 μmol CO2 mol(-1) (CE) and an air temperature (T) between 2.8 and 5.6 °C above ambient T (TE), during summer and winter. Net shoot CO2 exchange (Anet) was measured continuously on 1-year-old shoots and was used to calculate the accumulated carbon uptake and daily Asat and AQY. The accumulated carbon uptake, from 1 March to 30 June, was stimulated by 33, 44 and 61% when trees were exposed to CE, TE, and CE and TE combined, respectively. Air temperature strongly influenced the timing and extent of photosynthetic recovery expressed as AQY and Asat during the spring. Under elevated T (TE), the recovery of AQY and Asat commenced ∼10 days earlier and the activity of these parameters was significantly higher throughout the recovery period. In the absence of frost events, the photosynthetic recovery period was less than a week. However, frost events during spring slowed recovery so that full recovery could take up to 60 days to complete. Elevated [CO2] stimulated AQY and Asat on average by ∼10 and ∼50%, respectively, throughout the recovery period, but had minimal or no effect on the onset and length of the photosynthetic recovery period during the spring. However, AQY, Asat and Anet all recovered at significantly higher T (average +2.2 °C) in TE than in TA, possibly caused by acclimation or by shorter days and lower light levels during the early part of the recovery in TE compared with TA. The results suggest that predicted future climate changes will cause prominent stimulation of photosynthetic CO2 uptake in boreal Norway spruce forest during spring, mainly caused by elevated T

ELEVATED TEMPERATURE, SOIL MOISTURE AND SEASONALITY BUT NOT CO2 AFFECT CANOPY ASSIMILATION AND SYSTEM RESPIRATION IN SEEDLING DOUGLAS-FIR ECOSYSTEMS

Science.gov (United States)

We investigated the effects of elevated atmospheric CO2 and air temperature on C cycling in trees and associated soil system, focusing on canopy CO2 assimilation (Asys) and system CO2 loss through respiration (Rsys). We hypothesized that both elevated CO2 and elevated temperature...

Effects of elevated CO2 and nitrogen deposition on ecosystem carbon fluxes on the Sanjiang plain wetland in Northeast China.

Science.gov (United States)

Wang, Jianbo; Zhu, Tingcheng; Ni, Hongwei; Zhong, Haixiu; Fu, Xiaoling; Wang, Jifeng

2013-01-01

Increasing atmospheric CO2 and nitrogen (N) deposition across the globe may affect ecosystem CO2 exchanges and ecosystem carbon cycles. Additionally, it remains unknown how increased N deposition and N addition will alter the effects of elevated CO2 on wetland ecosystem carbon fluxes. Beginning in 2010, a paired, nested manipulative experimental design was used in a temperate wetland of northeastern China. The primary factor was elevated CO2, accomplished using Open Top Chambers, and N supplied as NH4NO3 was the secondary factor. Gross primary productivity (GPP) was higher than ecosystem respiration (ER), leading to net carbon uptake (measured by net ecosystem CO2 exchange, or NEE) in all four treatments over the growing season. However, their magnitude had interannual variations, which coincided with air temperature in the early growing season, with the soil temperature and with the vegetation cover. Elevated CO2 significantly enhanced GPP and ER but overall reduced NEE because the stimulation caused by the elevated CO2 had a greater impact on ER than on GPP. The addition of N stimulated ecosystem C fluxes in both years and ameliorated the negative impact of elevated CO2 on NEE. In this ecosystem, future elevated CO2 may favor carbon sequestration when coupled with increasing nitrogen deposition.

Effects of elevated atmospheric CO2 on dissolution of geological fluorapatite in water and soil.

Science.gov (United States)

Li, Zhen; Su, Mu; Tian, Da; Tang, Lingyi; Zhang, Lin; Zheng, Yangfan; Hu, Shuijin

2017-12-01

Most of phosphorus (P) is present as insoluble phosphorus-bearing minerals or organic forms in soil. Geological fluorapatite (FAp) is the dominant mineral-weathering source of P. In this study, FAp was added into water and soil under elevated CO 2 to investigate the pathway of P release. Two types of soils (an acidic soil from subtropical China and a saline-alkali soil from Tibet Plateau, China) with similar total P content were studied. In the solution, increased CO 2 in air enhanced the dissolution of FAp, i.e., from 0.04 to 1.18ppm for P and from 2.48 to 13.61ppm for Ca. In addition, release of Ca and P from FAp reached the maximum (2.14ppm for P and 13.84ppm for Ca) under the combination of elevated CO 2 and NaCl due to the increasing ion exchange. Consistent with the results from the solution, CO 2 elevation promoted P release more significantly (triple) in the saline-alkali soil than in the acidic soil. Therefore, saline-alkali soils in Tibet Plateau would be an important reservoir of available P under the global CO 2 rise. This study sheds the light on understanding the geological cycle of phosphorus. Copyright © 2017. Published by Elsevier B.V.

Soil warming enhances the hidden shift of elemental stoichiometry by elevated CO2 in wheat

DEFF Research Database (Denmark)

Li, Xiangnan; Jiang, Dong; Liu, Fulai

2016-01-01

sap and their partitioning in different organs of wheat plant during grain filling were investigated. Results showed that the combination of elevated [CO2] and soil warming improved wheat grain yield, but decreased plant K, Ca and Mg accumulation and their concentrations in the leaves, stems, roots......Increase in atmospheric CO2 concentration ([CO2]) and associated soil warming along with global climate change are expected to have large impacts on grain mineral nutrition in wheat. The effects of CO2 elevation (700 μmol l(-1)) and soil warming (+2.4 °C) on K, Ca and Mg concentrations in the xylem...... and grains. The reduced grain mineral concentration was attributed to the lowered mineral uptake as exemplified by both the decreased stomatal conductance and mineral concentration in the xylem sap. These findings suggest that future higher atmospheric [CO2] and warmer soil conditions may decrease...

Elevated CO{sub 2} and development of frost hardiness in Norway spruce (picea abies (L.) Karst.); Oekt CO{sub 2} og utvikling av frostherdighet i gran

Energy Technology Data Exchange (ETDEWEB)

Dalen, Lars Sandved

1998-09-01

This thesis discusses controlled laboratory experiments carried out to study the effects of CO{sub 2} pollution on Norwegian spruce. It was found that elevated CO{sub 2} increased height growth and biomass production. It slightly increased frost hardiness, but only at high nitrogen values. There was no evidence of adverse effects of elevated CO{sub 2} on the phenology of bud set and the development of frost hardiness. Although not statistically significant, there seemed to be a consistently higher concentration of soluble carbohydrates in one-season-old Norway spruce seedlings treated with elevated CO{sub 2}. This was not found in three-year-old seedlings grown in open top chambers, possibly indicating a down-regulation of photosynthesis or a transition from free to predetermined growth, and change in allocation of photosynthates with age. Treatment with high or low concentrations of CO{sub 2} and nitrogen fertilizer did not affect apoplastic chitinolytic activity during cold acclimation, nor were there any effects on antifreeze activity in these apoplastic extracts from cold acclimated needles. 149 refs., 21 figs., 8 tabs.

Putting prey and predator into the CO2 equation--qualitative and quantitative effects of ocean acidification on predator-prey interactions.

Science.gov (United States)

Ferrari, Maud C O; McCormick, Mark I; Munday, Philip L; Meekan, Mark G; Dixson, Danielle L; Lonnstedt, Öona; Chivers, Douglas P

2011-11-01

Little is known about the impact of ocean acidification on predator-prey dynamics. Herein, we examined the effect of carbon dioxide (CO(2)) on both prey and predator by letting one predatory reef fish interact for 24 h with eight small or large juvenile damselfishes from four congeneric species. Both prey and predator were exposed to control or elevated levels of CO(2). Mortality rate and predator selectivity were compared across CO(2) treatments, prey size and species. Small juveniles of all species sustained greater mortality at high CO(2) levels, while large recruits were not affected. For large prey, the pattern of prey selectivity by predators was reversed under elevated CO(2). Our results demonstrate both quantitative and qualitative consumptive effects of CO(2) on small and larger damselfish recruits respectively, resulting from CO(2)-induced behavioural changes likely mediated by impaired neurological function. This study highlights the complexity of predicting the effects of climate change on coral reef ecosystems. © 2011 Blackwell Publishing Ltd/CNRS.

Interactions between CO2, saline water and minerals during geological storage of CO2

International Nuclear Information System (INIS)

Hellevang, Helge

2006-06-01

The topic of this thesis is to gain a better understanding of interactions between injected CO 2 , aqueous solutions and formation mineralogies. The main focus is concerned with the potential role mineral reactions play in safe long term storage of CO 2 . The work is divided into an experimental part concentrated on the potential of dawsonite (NaAl(OH) 2 CO 3 ) as a permanent storage host of CO 2 , and the development of a new geochemical code ACCRETE that is coupled with the ATHENA multiphase flow simulator. The thesis is composed of two parts: (I) the first part introducing CO 2 storage, geochemical interactions and related work; and (II) the second part that consists of the papers. Part I is composed as follows: Chapter 2 gives a short introduction to geochemical reactions considered important during CO 2 storage, including a thermodynamic framework. Chapter 3 presents objectives of numerical work related to CO 2 -water-rock interactions including a discussion of factors that influence the outcome of numerical simulations. Chapter 4 presents the main results from paper A to E. Chapter 5 give some details about further research that we propose based on the present work and related work in the project. Several new activities have emerged from research on CO 2 -water-rock interaction during the project. Several of the proposed activities are already initiated. Papers A to F are then listed in Part II of the thesis after the citation list. The thesis presents the first data on the reaction kinetics of dawsonite at different pH (Paper A), and comprehensive numerical simulations, both batch- and large scale 3D reactive transport, that illustrate the role different carbonates have for safe storage of CO 2 in geological formations (Papers C to F). The role of dawsonite in CO 2 storage settings is treated throughout the study (Papers A to E) After the main part of the thesis (Part I and II), two appendices are included: Appendix A lists reactions that are included in the

Field experimental data for crop modeling of wheat growth response to nitrogen fertilizer, elevated CO2, water stress, and high temperature

Science.gov (United States)

Field experimental data of five experiments covering a wide range Field experimental data of five experiments covering a wide range of growing conditions are assembled for wheat growth and cropping systems modeling. The data include (i) an experiment on interactive effects of elevated CO2 by water a...

EFFECTS OF ELEVATED CO2 ON ROOT FUNCTION AND SOIL RESPIRATION IN A MOJAVE DESERT ECOSYSTEM

Energy Technology Data Exchange (ETDEWEB)

Nowak, Robert S.

2007-12-19

Increases in atmospheric CO{sub 2} concentration during the last 250 years are unequivocal, and CO{sub 2} will continue to increase at least for the next several decades (Houghton et al. 2001, Keeling & Whorf 2002). Arid ecosystems are some of the most important biomes globally on a land surface area basis, are increasing in area at an alarming pace (Dregne 1991), and have a strong coupling with regional climate (Asner & Heidebrecht 2005). These water-limited ecosystems also are predicted to be the most sensitive to elevated CO{sub 2}, in part because they are stressful environments where plant responses to elevated CO{sub 2} may be amplified (Strain & Bazzaz 1983). Indeed, all C{sub 3} species examined at the Nevada Desert FACE Facility (NDFF) have shown increased A{sub net} under elevated CO{sub 2} (Ellsworth et al. 2004, Naumburg et al. 2003, Nowak et al. 2004). Furthermore, increased shoot growth for individual species under elevated CO{sub 2} was spectacular in a very wet year (Smith et al. 2000), although the response in low to average precipitation years has been smaller (Housman et al. 2006). Increases in perennial cover and biomass at the NDFF are consistent with long term trends in the Mojave Desert and elsewhere in the Southwest, indicating C sequestration in woody biomass (Potter et al. 2006). Elevated CO{sub 2} also increases belowground net primary production (BNPP), with average increases of 70%, 21%, and 11% for forests, bogs, and grasslands, respectively (Nowak et al. 2004). Although detailed studies of elevated CO{sub 2} responses for desert root systems were virtually non-existent prior to our research, we anticipated that C sequestration may occur by desert root systems for several reasons. First, desert ecosystems exhibit increases in net photosynthesis and primary production at elevated CO{sub 2}. If large quantities of root litter enter the ecosystem at a time when most decomposers are inactive, significant quantities of carbon may be stored

The impact of long-term elevated CO2 on C and N retention in stable SOM pools

NARCIS (Netherlands)

Graaff, de M.A.; Kessel, van C.; Six, J.

2008-01-01

Elevated atmospheric CO2 frequently increases plant production and concomitant soil C inputs, which may cause additional soil C sequestration. However, whether the increase in plant production and additional soil C sequestration under elevated CO2 can be sustained in the long-term is unclear. One

Response of the rhizosphere prokaryotic community of barley (Hordeum vulgare L.) to elevated atmospheric CO2 concentration in open-top chambers.

Science.gov (United States)

Szoboszlay, Márton; Näther, Astrid; Mitterbauer, Esther; Bender, Jürgen; Weigel, Hans-Joachim; Tebbe, Christoph C

2017-08-01

The effect of elevated atmospheric CO 2 concentration [CO 2 ] on the diversity and composition of the prokaryotic community inhabiting the rhizosphere of winter barley (Hordeum vulgare L.) was investigated in a field experiment, using open-top chambers. Rhizosphere samples were collected at anthesis (flowering stage) from six chambers with ambient [CO 2 ] (approximately 400 ppm) and six chambers with elevated [CO 2 ] (700 ppm). The V4 region of the 16S rRNA gene was PCR-amplified from the extracted DNA and sequenced on an Illumina MiSeq instrument. Above-ground plant biomass was not affected by elevated [CO 2 ] at anthesis, but plants exposed to elevated [CO 2 ] had significantly higher grain yield. The composition of the rhizosphere prokaryotic communities was very similar under ambient and elevated [CO 2 ]. The dominant taxa were Bacteroidetes, Actinobacteria, Alpha-, Gamma-, and Betaproteobacteria. Elevated [CO 2 ] resulted in lower prokaryotic diversity in the rhizosphere, but did not cause a significant difference in community structure. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

The alleviating effect of elevated CO2 on heat stress susceptibility of two wheat (Triticum aestivum L.) cultivars

DEFF Research Database (Denmark)

Kjær, Katrine Heinsvig; Ottosen, Carl-Otto; Rosenqvist, Eva S. K.

2013-01-01

efficiency of photosystem II (PSII) photochemistry (Fv/Fm) and contents of pigments and carbohydrates in leaves were analysed before and during the stress treatments as well as after one day of recovery. Heat stress reduced PN and Fv/Fm in both wheat cultivars, but plants grown in elevated CO2 maintained...... higher PN and Fv/Fm in comparison to plants grown in ambient CO2. Heat stress reduced leaf chlorophyll contents and increased leaf sucrose contents in both cultivars grown at ambient and elevated CO2. The content of hexoses in the leaves increased mainly in the tolerant cultivar in response...... to the combination of elevated CO2 and heat stress. The results show that heat stress tolerance in wheat is related to cultivar origin, the phenological stage of the plants and can be alleviated by elevated CO2. This confirms the complex interrelation between environmental factors and genotypic traits that influence...

Evolution and challenges of dynamic global vegetation models for some aspects of plant physiology and elevated atmospheric CO2.

Science.gov (United States)

Rezende, L F C; Arenque, B C; Aidar, S T; Moura, M S B; Von Randow, C; Tourigny, E; Menezes, R S C; Ometto, J P H B

2016-07-01

Dynamic global vegetation models (DGVMs) simulate surface processes such as the transfer of energy, water, CO2, and momentum between the terrestrial surface and the atmosphere, biogeochemical cycles, carbon assimilation by vegetation, phenology, and land use change in scenarios of varying atmospheric CO2 concentrations. DGVMs increase the complexity and the Earth system representation when they are coupled with atmospheric global circulation models (AGCMs) or climate models. However, plant physiological processes are still a major source of uncertainty in DGVMs. The maximum velocity of carboxylation (Vcmax), for example, has a direct impact over productivity in the models. This parameter is often underestimated or imprecisely defined for the various plant functional types (PFTs) and ecosystems. Vcmax is directly related to photosynthesis acclimation (loss of response to elevated CO2), a widely known phenomenon that usually occurs when plants are subjected to elevated atmospheric CO2 and might affect productivity estimation in DGVMs. Despite this, current models have improved substantially, compared to earlier models which had a rudimentary and very simple representation of vegetation-atmosphere interactions. In this paper, we describe this evolution through generations of models and the main events that contributed to their improvements until the current state-of-the-art class of models. Also, we describe some main challenges for further improvements to DGVMs.

Effects of elevated CO2 and nitrogen deposition on ecosystem carbon fluxes on the Sanjiang plain wetland in Northeast China.

Directory of Open Access Journals (Sweden)

Jianbo Wang

Full Text Available BACKGROUND: Increasing atmospheric CO2 and nitrogen (N deposition across the globe may affect ecosystem CO2 exchanges and ecosystem carbon cycles. Additionally, it remains unknown how increased N deposition and N addition will alter the effects of elevated CO2 on wetland ecosystem carbon fluxes. METHODOLOGY/PRINCIPAL FINDINGS: Beginning in 2010, a paired, nested manipulative experimental design was used in a temperate wetland of northeastern China. The primary factor was elevated CO2, accomplished using Open Top Chambers, and N supplied as NH4NO3 was the secondary factor. Gross primary productivity (GPP was higher than ecosystem respiration (ER, leading to net carbon uptake (measured by net ecosystem CO2 exchange, or NEE in all four treatments over the growing season. However, their magnitude had interannual variations, which coincided with air temperature in the early growing season, with the soil temperature and with the vegetation cover. Elevated CO2 significantly enhanced GPP and ER but overall reduced NEE because the stimulation caused by the elevated CO2 had a greater impact on ER than on GPP. The addition of N stimulated ecosystem C fluxes in both years and ameliorated the negative impact of elevated CO2 on NEE. CONCLUSION/SIGNIFICANCE: In this ecosystem, future elevated CO2 may favor carbon sequestration when coupled with increasing nitrogen deposition.

Response of needle dark respiration of Pinus koraiensis and Pinus sylvestriformis to elevated CO2 concentrations for four growing seasons' exposure

Institute of Scientific and Technical Information of China (English)

ZHOU YuMei; HAN ShiJie; ZHANG HaiSen; XIN LiHua; ZHENG JunQiang

2007-01-01

The long-term effect of elevated CO2 concentrations on needle dark respiration of two coniferous species-Pinus koraiensis and Pinus sylvestriformis on the Changbai Mountain was investigated using open-top chambers. P. Koraiensis and P. Sylvestriformis were exposed to 700,500μmol·mol-1 CO2 and ambient CO2(approx.350 μmol·mol-1)for four growing seasons. Needle dark respiration was measurd during the second, third and fourth growing seasons' exposure to elevated CO2.The results showed that needle dark respiration rate increased for P. Koraiensis and P. Sylvestriformis grown at elevated CO2 concentrations during the second growing season, could be attributed to the change of carbohydrate and/or nitrogen content of needles. Needle dark respiration of P. Koraiensis was stimulated and that of P. Sylvestriformis was inhibited by elevated CO2 concentrations during the third growing season. Different response of the two tree species to elevated CO2 mainly resulted from the difference in the growth rate. Elevated CO2 concentrations inhibited needle dark respiration of both P. Koraiensis and P. Sylvestriformis during the fourth growing season. There was consistent trend between the short-term effect and the long-term effect of elevated CO2 on needle dark respiration in P. Sylvestriformis during the third growing season by changing measurement CO2 concentrations. However, the short-term effect was different from the long-term effect for P. Koraiensis. Response of dark respiration of P. Koraiensis and P. Sylvestriformis to elevated CO2 concentrations was related to the treatment time of CO2 and the stage of growth and development of plant. The change of dark respiration for the two tree species was determined by the direct effect of CO2 and long-term acclimation. The prediction of the long-term response of needle dark respiration to elevated CO2 concentration based on the short-term response is in dispute.

Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

Science.gov (United States)

Asko Noormets; Olevi Kull; Anu Sober; Mark E. Kubiske; David F. Karnosky

2010-01-01

The effect of elevated CO2 and O3 on apparent quantum yield (ø), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus...

Water availability drives gas exchange and growth of trees in northeastern US, not elevated CO2 and reduced acid deposition.

Science.gov (United States)

Levesque, Mathieu; Andreu-Hayles, Laia; Pederson, Neil

2017-04-10

Dynamic global vegetation models (DGVM) exhibit high uncertainty about how climate change, elevated atmospheric CO 2 (atm. CO 2 ) concentration, and atmospheric pollutants will impact carbon sequestration in forested ecosystems. Although the individual roles of these environmental factors on tree growth are understood, analyses examining their simultaneous effects are lacking. We used tree-ring isotopic data and structural equation modeling to examine the concurrent and interacting effects of water availability, atm. CO 2 concentration, and SO 4 and nitrogen deposition on two broadleaf tree species in a temperate mesic forest in the northeastern US. Water availability was the strongest driver of gas exchange and tree growth. Wetter conditions since the 1980s have enhanced stomatal conductance, photosynthetic assimilation rates and, to a lesser extent, tree radial growth. Increased water availability seemingly overrides responses to reduced acid deposition, CO 2 fertilization, and nitrogen deposition. Our results indicate that water availability as a driver of ecosystem productivity in mesic temperate forests is not adequately represented in DGVMs, while CO 2 fertilization is likely overrepresented. This study emphasizes the importance to simultaneously consider interacting climatic and biogeochemical drivers when assessing forest responses to global environmental changes.

Climate change and genetically modified insecticidal plants. Plant-herbivore interactions and secondary chemistry of Bt Cry1Ac-toxin producing oilseed rape (Brassica napus L.) under elevated CO{sub 2} or O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Himanen, S.

2008-07-01

Transgenic insect-resistant plants producing Bacillus thuringiensis (Bt) crystalline endotoxins are the first commercial applications of genetically modified crops and their use has steadily expanded over the last ten years. Together with the expanding agricultural use of transgenic crops, climate change is predicted to be among the major factors affecting agriculture in the coming years. Plants, herbivores and insects of higher trophic levels are all predicted to be affected by the current atmospheric climate change. However, only very few studies to date have addressed the sustained use and herbivore interactions of Bt-producing plants under the influence of these abiotic factors. The main objective of this study was to comparatively assess the performance of a Bt Cry1Ac toxin-producing oilseed rape line and its non-transgenic parent line in terms of vegetative growth and allocation to secondary defence compounds (glucosinolates and volatile terpenoids), and the performance of Bt-target and nontarget insect herbivores as well as tritrophic interaction functioning on these lines. For this, several growth chamber experiments with vegetative stage non-Bt and Bt plants facing exposures to doubled atmospheric CO{sub 2} level alone or together with increased temperature and different regimes of elevated O{sub 3} were conducted. The main hypothesis of this work was that Bt-transgenic plants have reduced performance or allocation to secondary compounds due to the cost of producing Bt toxin under changed abiotic environments. The Bt-transgenic oilseed rape line exhibited slightly delayed vegetative growth and had increased nitrogen and reduced carbon content compared to the non-transgenic parent line, but the physiological responses (i.e. biomass gain and photosynthesis) of the plant lines to CO{sub 2} and O{sub 3} enhancements were equal. Two aphid species, non-susceptible to Bt Cry1Ac, showed equal performance and reproduction on both plant lines under elevated CO{sub 2

Amazon rainforest responses to elevated CO2: Deriving model-based hypotheses for the AmazonFACE experiment

Science.gov (United States)

Rammig, A.; Fleischer, K.; Lapola, D.; Holm, J.; Hoosbeek, M.

2017-12-01

Increasing atmospheric CO2 concentration is assumed to have a stimulating effect ("CO2 fertilization effect") on forest growth and resilience. Empirical evidence, however, for the existence and strength of such a tropical CO2 fertilization effect is scarce and thus a major impediment for constraining the uncertainties in Earth System Model projections. The implications of the tropical CO2 effect are far-reaching, as it strongly influences the global carbon and water cycle, and hence future global climate. In the scope of the Amazon Free Air CO2 Enrichment (FACE) experiment, we addressed these uncertainties by assessing the CO2 fertilization effect at ecosystem scale. AmazonFACE is the first FACE experiment in an old-growth, highly diverse tropical rainforest. Here, we present a priori model-based hypotheses for the experiment derived from a set of 12 ecosystem models. Model simulations identified key uncertainties in our understanding of limiting processes and derived model-based hypotheses of expected ecosystem responses to elevated CO2 that can directly be tested during the experiment. Ambient model simulations compared satisfactorily with in-situ measurements of ecosystem carbon fluxes, as well as carbon, nitrogen, and phosphorus stocks. Models consistently predicted an increase in photosynthesis with elevated CO2, which declined over time due to developing limitations. The conversion of enhanced photosynthesis into biomass, and hence ecosystem carbon sequestration, varied strongly among the models due to different assumptions on nutrient limitation. Models with flexible allocation schemes consistently predicted an increased investment in belowground structures to alleviate nutrient limitation, in turn accelerating turnover rates of soil organic matter. The models diverged on the prediction for carbon accumulation after 10 years of elevated CO2, mainly due to contrasting assumptions in their phosphorus cycle representation. These differences define the expected