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Michael G. Ryan - One of the best experts on this subject based on the ideXlab platform.
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growth and Maintenance Respiration rates of aspen black spruce and jack pine stems at northern and southern boreas sites
Tree Physiology, 1997Co-Authors: M B Lavigne, Michael G. RyanAbstract:: We measured stem Respiration rates during and after the 1994 growing season of three common boreal tree species at sites near the northern and southern boundaries of the closed-canopy boreal forest in central Canada. The growth Respiration coefficient (r(g); carbon efflux per micro mole of carbon incorporated in structural matter) varied between 0.25 and 0.76, and was greatest for black spruce (Picea mariana (Mill.) B.S.P.), least for jack pine (Pinus banksiana Lamb.) and intermediate for trembling aspen (Populus tremuloides Michx.). There was a consistent trend for higher r(g) at northern sites than at southern sites. Maintenance Respiration rates at 15 degrees C (r(m)) varied from 0.5 to 2.7 nmol C mol(-1) C(sapwood) s(-1). Values of r(m) were high at sapling-stage jack pine sites and mature black spruce sites, and low at mature trembling aspen and mature jack pine sites. We found significant relationships between annual Maintenance Respiration and sapwood relative growth rate and sapwood volume per unit of stem surface area that explained much of the within-stand and between-stand variability. Because of the large differences in parameter values among sites, we conclude that the use of stand-specific respiratory parameters may improve model predictions of ecosystem process models over the use of generic parameter values.
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Foliage, fine-root, woody-tissue and stand Respiration in Pinus radiata in relation to nitrogen status.
Tree Physiology, 1996Co-Authors: Michael G. Ryan, Robert M. Hubbard, Silvia Pongracic, R. J. Raison, Ross E. McmurtrieAbstract:: We measured Respiration of 20-year-old Pinus radiata D. Don trees growing in control (C), irrigated (I), and irrigated + fertilized (IL) stands in the Biology of Forest Growth experimental plantation near Canberra, Australia. Respiration was measured on fully expanded foliage, live branches, boles, and fine and coarse roots to determine the relationship between CO(2) efflux, tissue temperature, and biomass or nitrogen (N) content of individual tissues. Efflux of CO(2) from foliage (dark Respiration at night) and fine roots was linearly related to biomass and N content, but N was a better predictor of CO(2) efflux than biomass. Respiration (assumed to be Maintenance) per unit N at 15 degrees C and a CO(2) concentration of 400 micro mol mol(-1) was 1.71 micro mol s(-1) mol(-1) N for foliage and 11.2 micro mol s(-1) mol(-1) N for fine roots. Efflux of CO(2) from stems, coarse roots and branches was linearly related to sapwood volume (stems) or total volume (branches + coarse roots) and growth, with rates for Maintenance Respiration at 15 degrees C ranging from 18 to 104 micro mol m(-3) s(-1). Among woody components, branches in the upper canopy and small diameter coarse roots had the highest Respiration rates. Stem Maintenance Respiration per unit sapwood volume did not differ among treatments. Annual C flux was estimated by summing (1) dry matter production and Respiration of aboveground components, (2) annual soil CO(2) efflux minus aboveground litterfall, and (3) the annual increment in coarse root biomass. Annual C flux was 24.4, 25.3 and 34.4 Mg ha(-1) year(-1) for the C, I and IL treatments, respectively. Total belowground C allocation, estimated as the sum of (2) and (3) above, was equal to the sum of root Respiration and estimated root production in the IL treatment, whereas in the nutrient-limited C and I treatments, total belowground C allocation was greater than the sum of root Respiration and estimated root production, suggesting higher fine root turnover or increased allocation to mycorrhizae and root exudation. Carbon use efficiency, the ratio of net primary production to assimilation, was similar among treatments for aboveground tissues (0.43-0.50). Therefore, the proportion of assimilation used for construction and Maintenance Respiration on an annual basis was also similar among treatments.
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foliar Maintenance Respiration of subalpine and boreal trees and shrubs in relation to nitrogen content
Plant Cell and Environment, 1995Co-Authors: Michael G. RyanAbstract:A nitrogen-based model of Maintenance Respiration (R m ) would link R m with nitrogen-based photosynthesis models and enable simpler estimation of dark Respiration flux from forest canopies. To test whether an N-based model of R m would apply generally to foliage of boreal and subalpine woody plants, I measured R m (CO 2 efflux at night from fully expanded foliage) for foliage of seven species of trees and shrubs in the northern boreal forest (near Thompson, Manitoba, Canada) and seven species in the subalpine montane forest (near Fraser, Colorado, USA). At 10 °C, average R m for boreal foliage ranged from 0.94 to 6-8 μmol kg -1 s -1 (0.18-0.58 μmol m -2 s -1 ) and for subalpine foliage it ranged from 0.99 to 7.6 μmol kg -1 s -1 0.28-0.64 μmol m -2 s -1 ). CO 2 efflux at 10 °C for the samples was only weakly correlated with sample weight r = 0-11) and leaf area (r = 0.58). However, CO 2 efflux per unit foliage weight was highly correlated with foliage N concentration [r=0.83, CO 2 flux at 10°C (mol kg -1 s -1 ) = 2.62 x foliage N (mol kg -1 )], and slopes were statistically similar for the boreal and subalpine sites (P = 0.28). CO 2 efflux per unit of foliar N was 1.8 times that reported for a variety of crop and wildland species growing in warmer climates.
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Woody tissue Maintenance Respiration of four conifers in contrasting climates
Oecologia, 1995Co-Authors: Michael G. Ryan, Stith T. Gower, Robert M. Hubbard, Richard H. Waring, Henry L. Gholz, Wendell P. Cropper, Steven W. RunningAbstract:We estimate Maintenance Respiration for boles of four temperate conifers (ponderosa pine, western hemlock, red pine, and slash pine) from CO_2 efflux measurements in autumn, when construction Respiration is low or negligible. Maintenance Respiration of stems was linearly related to sapwood volume for all species; at 10°C, Respiration per unit sapwood volume ranged from 4.8 to 8.3 μmol CO_2 m^−3 s^−1. For all sites combined, Respiration increased exponentially with temperature ( Q _ 10 =1.7, r ^2=0.78). We estimate that Maintenance Respiration of aboveground woody tissues of these conifers consumes 52–162 g C m^−2 y^−1, or 5–13% of net daytime carbon assimilation annually. The fraction of annual net daytime carbon fixation used for stem Maintenance Respiration increased linearly with the average annual temperature of the site.
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Woody-tissue Respiration for Simarouba amara and Minquartia guianensis, two tropical wet forest trees with different growth habits
Oecologia, 1994Co-Authors: Michael G. Ryan, Robert M. Hubbard, Deborah A. Clark, Robert L. SanfordAbstract:We measured CO_2 efflux from stems of two tropical wet forest trees, both found in the canopy, but with very different growth habits. The species were Simarouba amara , a fast-growing species associated with gaps in old-growth forest and abundant in secondary forest, and Minquartia guianensis , a slow-growing species tolerant of low-light conditions in old-growth forest. Per unit of bole surface, CO_2 efflux averaged 1.24 μmol m^−2 s^−1 for Simarouba and 0.83 μmol m^−2s^−1 for Minquartia . CO_2 efflux was highly correlated with annual wood production ( r ^2=0.65), but only weakly correlated with stem diameter ( r ^2=0.22). We also partitioned the CO_2 efflux into the functional components of construction and Maintenance Respiration. Construction Respiration was estimated from annual stem dry matter production and Maintenance Respiration by subtracting construction Respiration from the instantaneous CO_2 flux. Estimated Maintenance Respiration was linearly related to sapwood volume (39.6 μmol m^−3s^−1 at 24.6° C, r ^2=0.58), with no difference in the rate for the two species. Maintenance Respiration per unit of sapwood volume for these tropical wet forest trees was roughly twice that of temperate conifers. A model combining construction and Maintenance Respiration estimated CO_2 very well for these species ( r ^2=0.85). For our sample, Maintenance Respiration was 54% of the total CO_2 efflux for Simarouba and 82% for Minquartia . For our sample, sapwood volume averaged 23% of stem volume when weighted by tree size, or 40% with no size weighting. Using these fractions, and a published estimate of aboveground dry-matter production, we estimate the annual cost of woody tissue Respiration for primary forest at La Selva to be 220 or 350 g C m^−2 year^−1, depending on the assumed sapwood volume. These costs are estimated to be less than 13% of the gross production for the forest.
M B Lavigne - One of the best experts on this subject based on the ideXlab platform.
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changes in stem Respiration rate during cambial reactivation can be used to refine estimates of growth and Maintenance Respiration
New Phytologist, 2004Co-Authors: M B Lavigne, C H A Little, R T RidingAbstract:Summary • To determine if stem Respiration (r) varied during cambial reactivation, r was measured during March–July in untreated trees and seedlings, debudded seedlings and girdled seedlings of white ash (Fraxinus americana), red maple (Acer rubrum) and balsam fir (Abies balsamea). • The r was measured using an infrared gas-analysis system. Cambial reactivation was monitored by light microscopy. • After increasing modestly about the time of cambial cell swelling, r declined to a minimum for several weeks and then increased markedly as rapid xylem production (XP) began. Growth Respiration (Rg) over the experimental period was positively correlated with XP over the same time span, with differences in wood anatomy and XP-measurement method accounting for differences among species. A weak, positive trend was observed between Maintenance Respiration (Rm) and XP. Rm varied among species. • The marked springtime increase in r is a nondestructive marker for the onset of rapid XP. Measurements of r made after cambial cell swelling and before rapid XP are appropriate for applying the mature-tissue method to estimate Rg and Rm. Rg reflects XP, particularly the width of differentiating xylem.
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growth and Maintenance Respiration rates of aspen black spruce and jack pine stems at northern and southern boreas sites
Tree Physiology, 1997Co-Authors: M B Lavigne, Michael G. RyanAbstract:: We measured stem Respiration rates during and after the 1994 growing season of three common boreal tree species at sites near the northern and southern boundaries of the closed-canopy boreal forest in central Canada. The growth Respiration coefficient (r(g); carbon efflux per micro mole of carbon incorporated in structural matter) varied between 0.25 and 0.76, and was greatest for black spruce (Picea mariana (Mill.) B.S.P.), least for jack pine (Pinus banksiana Lamb.) and intermediate for trembling aspen (Populus tremuloides Michx.). There was a consistent trend for higher r(g) at northern sites than at southern sites. Maintenance Respiration rates at 15 degrees C (r(m)) varied from 0.5 to 2.7 nmol C mol(-1) C(sapwood) s(-1). Values of r(m) were high at sapling-stage jack pine sites and mature black spruce sites, and low at mature trembling aspen and mature jack pine sites. We found significant relationships between annual Maintenance Respiration and sapwood relative growth rate and sapwood volume per unit of stem surface area that explained much of the within-stand and between-stand variability. Because of the large differences in parameter values among sites, we conclude that the use of stand-specific respiratory parameters may improve model predictions of ecosystem process models over the use of generic parameter values.
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estimating stem Maintenance Respiration rates of dissimilar balsam fir stands
Tree Physiology, 1996Co-Authors: M B Lavigne, Steven E Franklin, E R HuntAbstract:: Stem Maintenance Respiration rates were measured in five contrasting balsam fir (Abies balsamea (L.) Mill.) stands. At 15 degrees C, average Respiration rates for individual stands ranged from 120 to 235 micro mol m(-3) s(-1) when expressed per unit of sapwood volume, from 0.80 to 1.80 micro mol m(-2) s(-1) when expressed per unit of stem surface area, and from 0.50 to 1.00 micro mol g(-1) s(-1) when expressed per unit of nitrogen in the living stem biomass, but differences among stands were not statistically significant. Coefficients of variation ranged from 50 to 100% within stands and were similar for all bases used to express Respiration rates. Coefficients of determination for regressions between chamber flux and chamber values of sapwood volume, stem surface area and nitrogen content varied between stands and no one base was consistently higher than the other bases. We conclude that the bases for expressing stem Respiration are equally useful. Respiration rates were more closely correlated to stem temperature observed approximately 2 h earlier than to current stem temperature. Among stands, annual stem Maintenance Respiration per hectare varied from 0.1 to 0.4 Mmol ha(-1) year(-1), primarily because of large differences in sapwood volumes per hectare. Annual stem Maintenance Respiration per unit of leaf area ranged from 3 to 6 mol m(-2) year(-1), increasing as sapwood volume per hectare increased.
Marc W Van Iersel - One of the best experts on this subject based on the ideXlab platform.
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respiratory q10 of marigold tagetes patula in response to long term temperature differences and its relationship to growth and Maintenance Respiration
Physiologia Plantarum, 2006Co-Authors: Marc W Van IerselAbstract:Acclimation of Respiration to temperature is not well understood. To determine whether whole plant Respiration responses to long-term temperature treatments can be described using the Q10 concept, the CO2 exchange rate of marigolds (Tagetes patula L. ‘Queen Sophia’), grown at 20°C or 30°C, was measured for 62 days. When plants of the same age were compared, plants grown at 20°C consistently had a higher specific Respiration (Rspc) than plants grown at 30°C (long-term Q10= 0.71–0.97). This was due to a combination of greater dry mass at 30°C and a decrease in Rspc with increasing mass. When plants of the same dry mass were compared, the long-term Q10 was 1.35–1.55; i.e. Rspc was higher at 30°C than at 20°C. Whole plant Respiration could be accurately described by dividing Respiration into growth and Maintenance components. The Maintenance Respiration coefficient was higher at 30°C than at 20°C, while the growth Respiration coefficient was lower at 30°C, partly because of temperature-dependent changes in plant composition. These results suggest difficulties with interpreting temperature effects on whole plant Respiration, because conclusions depend greatly on whether plants of the same age or mass are compared. These difficulties can be minimized by describing whole plant Respiration on the basis of growth and Maintenance components.
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Respiratory Q10 of marigold (Tagetes patula) in response to long‐term temperature differences and its relationship to growth and Maintenance Respiration
Physiologia Plantarum, 2006Co-Authors: Marc W Van IerselAbstract:Acclimation of Respiration to temperature is not well understood. To determine whether whole plant Respiration responses to long-term temperature treatments can be described using the Q10 concept, the CO2 exchange rate of marigolds (Tagetes patula L. ‘Queen Sophia’), grown at 20°C or 30°C, was measured for 62 days. When plants of the same age were compared, plants grown at 20°C consistently had a higher specific Respiration (Rspc) than plants grown at 30°C (long-term Q10= 0.71–0.97). This was due to a combination of greater dry mass at 30°C and a decrease in Rspc with increasing mass. When plants of the same dry mass were compared, the long-term Q10 was 1.35–1.55; i.e. Rspc was higher at 30°C than at 20°C. Whole plant Respiration could be accurately described by dividing Respiration into growth and Maintenance components. The Maintenance Respiration coefficient was higher at 30°C than at 20°C, while the growth Respiration coefficient was lower at 30°C, partly because of temperature-dependent changes in plant composition. These results suggest difficulties with interpreting temperature effects on whole plant Respiration, because conclusions depend greatly on whether plants of the same age or mass are compared. These difficulties can be minimized by describing whole plant Respiration on the basis of growth and Maintenance components.
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Respiratory Q10 of Lettuce Increases with Increasing Plant Size
Hortscience, 2004Co-Authors: Marc W Van IerselAbstract:Literature reports on the Q10 for Respiration vary widely, both within and among species. Plant size and metabolic activity may be responsible for some of this variation. To test this, Respiration of whole lettuce plants was measured at temperatures ranging from 6 to 31 °C during a 24-h period. Subsequently, plant growth rate (in moles of carbon per day) was determined by measuring the CO2 exchange rate of the same plants during a 24-h period. Environmental conditions during this 24-h period resembled those that the plants were exposed to in the greenhouse. The measured growth rate was then used to estimate the relative growth rate (RGR) of the plants. The respiratory Q10 ranged from 1.4 for small plants to 1.75 for large plants. The increase in Q10 with increasing plant size was highly significant, as was the decrease in Q10 with increasing RGR. However, growth rate had little or no effect on the respiratory Q10. One possible explanation for these findings is that the Q10 depends on the ratio of growth to Maintenance Respiration (which is directly related to RGR). The growth Respiration coefficient generally is considered to be temperature-insensitive, while the Maintenance Respiration coefficient normally increases with increasing temperature. Based on this concept, the Q10 for the Maintenance Respiration coefficient can be estimated as the estimated Q10 at a RGR of zero (i.e. no growth and thus no growth Respiration), which was 1.65 in this experiment. Although the concept of dividing Respiration into growth and Maintenance fractions remains controversial, it is useful for explaining changes in respiratory Q10 during plant development.
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growth Respiration Maintenance Respiration and carbon fixation of vinca a time series analysis
Journal of the American Society for Horticultural Science, 2000Co-Authors: Marc W Van Iersel, Lynne SeymourAbstract:Respiration is important in the overall carbon balance of plants, and can be separated into growth (R g) and Maintenance Respiration (Rm). Estimation of Rg and Rm throughout plant development is difficult with traditional approaches. Here, we describe a new method to determine ontogenic changes in R g and Rm. The CO2 exchange rate of groups of 28 'Cooler Peppermint' vinca plants ( Catharanthus roseus (L.) G. Don.) was measured at 20 min intervals for 2 weeks. These data were used to calculate daily carbon gain (DCG, a measure of growth rate) and cumulative carbon gain (CCG, a measure of plant size). Growth and Maintenance Respiration were estimated based on the assumption that they are functions of DCG and CCG, respectively. Results suggested a linear relationship between DCG and R g. Initially, Rm was three times larger than R g, but they were similar at the end of the experiment. The decrease in the fraction of total available carbohydrates that was used for R m resulted in an increase in carbon use efficiency from 0.51 to 0.67 mol·mol -1 during the 2-week period. The glucose requirement of the plants was determined from R g, DCG, and the carbon fraction of the plant material and estimated to be 1.39 g·g -1 , while the Maintenance coefficient was estimated to be 0.031 g·g -1 ·d -1 at the end of the experiment. These results are similar to values reported previously for other species. This suggests that the use of semicontinuous CO 2 exchange measurements for estimating Rg and Rm yields reasonable results.
Richard H. Waring - One of the best experts on this subject based on the ideXlab platform.
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Woody tissue Maintenance Respiration of four conifers in contrasting climates
Oecologia, 1995Co-Authors: Michael G. Ryan, Stith T. Gower, Robert M. Hubbard, Richard H. Waring, Henry L. Gholz, Wendell P. Cropper, Steven W. RunningAbstract:We estimate Maintenance Respiration for boles of four temperate conifers (ponderosa pine, western hemlock, red pine, and slash pine) from CO_2 efflux measurements in autumn, when construction Respiration is low or negligible. Maintenance Respiration of stems was linearly related to sapwood volume for all species; at 10°C, Respiration per unit sapwood volume ranged from 4.8 to 8.3 μmol CO_2 m^−3 s^−1. For all sites combined, Respiration increased exponentially with temperature ( Q _ 10 =1.7, r ^2=0.78). We estimate that Maintenance Respiration of aboveground woody tissues of these conifers consumes 52–162 g C m^−2 y^−1, or 5–13% of net daytime carbon assimilation annually. The fraction of annual net daytime carbon fixation used for stem Maintenance Respiration increased linearly with the average annual temperature of the site.
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Maintenance Respiration and stand development in a subalpine lodgepole pine forest
Ecology, 1992Co-Authors: Michael G. Ryan, Richard H. WaringAbstract:We examined a chronosequence of subalpine lodgepole pine stands to test the hypothesis that low net primary production in older forest stands is caused by higher Maintenance Respiration costs of woody tissues. We predicted that Respiration of woody tissues (particularly stem sapwood) would be greater in older stands and that the higher Maintenance costs would account for observed low wood production. For a unit of ground surface, the carbon flux involved in wood production and associated construction respi- ration was 210 gm-2-yr-l in a 40-yr-old stand, but declined to 46 g.m-2.yr-l in a 245- yr-old stand. However, Maintenance Respiration of woody tissues in stems and branches consumed only 61 g.m-2.yr-l in the 40-yr-old stand and 79 g-m-2 yr-l in the 245-yr-old stand. The slight, nonsignificant increase in Maintenance Respiration of woody tissues could not explain the dramatic decline in aboveground wood production in the old-growth stand.
Stan D Wullschleger - One of the best experts on this subject based on the ideXlab platform.
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growth and Maintenance Respiration in leaves of northern red oak seedlings and mature trees after 3 years of ozone exposure
Plant Cell and Environment, 1996Co-Authors: Stan D Wullschleger, Paul J Hanson, G S EdwardsAbstract:A two-component model of growth and Maintenance Respiration is used to study the response of northern red oak (Quercus rubra L.) seedlings and 32-year-old trees to sub-ambient (10 μmol h; cumulative dose based on 7 h daily mean), ambient (43 μmol h), and twice-ambient (85 μmolh) ozone. The relative growth rates (RGR) of leaves sampled from seedlings and trees were similar across treatments, as were specific leaf Respiration rates (SRR). Growth coefficients estimated from the SRR versus RGR relationship averaged 25-3 mol CO2 kg−1 leaf dry mass produced for seedlings and 21-5 mol kg−1 for trees. Maintenance coefficients ranged from 0-89 to 1-07 mol CO2 kg−1 leaf dry mass d−1 for seedlings and from 0-64 to 0-84 mol kg-1 d−1 for trees. Neither coefficient was affected by ozone. Leaves sampled throughout the growing season also showed little response of Respiration to ozone. This occurred despite a 30% reduction in net photosynthesis for trees grown at twice-ambient ozone. These results suggest that growth and Maintenance Respiration in young northern red oak leaves are not affected by ozone and that in older leaves injury can occur without a parallel increase in so-called ‘Maintenance’ Respiration.
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growth and Maintenance Respiration in stems of quercus alba after four years of co2 enrichment
Physiologia Plantarum, 1995Co-Authors: Stan D Wullschleger, Richard J Norby, Paul J HansonAbstract:Atmospheric CO2 enrichment is increasingly being reported to inhibit leaf and whole-plant Respiration. It is not known, however, whether this response is unique to foliage or whether woody-tissue Respiration might be affected as well. This was examined for mid-canopy stem segments of white oak (Quercus alba L.) trees that had been grown in open-top field chambers and exposed to either ambient or ambient + 300 µmol mol−1 CO2 over a 4-year period. Stem Respiration measurements were made throughout 1992 by using an infrared gas analyzer and a specially designed in situ cuvette. Rates of woody-tissue Respiration were similar between CO2 treatments prior to leaf initiation and after leaf senescence, but were several fold greater for saplings grown at elevated concentrations of CO2 during much of the growing season. These effects were most evident on 7 July when stem Respiration rates for trees exposed to elevated CO2 concentrations were 7.25 compared to 3.44 µmol CO2 m−2 s−1 for ambient-grown saplings. While other explanations must be explored, greater rates of stem Respiration for saplings grown at elevated CO2 concentrations were consistent with greater rates of stem growth and more stem-wood volume present at the time of measurement. When rates of stem growth were at their maximum (7 July to 3 August), growth Respiration accounted for about 80 to 85% of the total respiratory costs of stems at both CO2 treatments, while 15 to 20% supported the costs of stem-wood Maintenance. Integrating growth and Maintenance Respiration throughout the season, taking into account treatment differences in stem growth and volume, indicated that there were no significant effects of elevated CO2 concentration on either respiratory process. Quantitative estimates that could be used in modeling the costs of woody-tissue growth and Maintenance Respiration are provided.
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growth and Maintenance Respiration in leaves of liriodendron tulipifera l exposed to long term carbon dioxide enrichment in the field
New Phytologist, 1992Co-Authors: Stan D Wullschleger, Richard J Norby, Carla A GundersonAbstract:summary Specific Respiration rate (SRR) was mathematically partitioned into its growth and Maintenance components for leaves of yellow-poplar (Liriodendron tulipifera L.) after 3 yr of CO2 enrichment in open-top field chambers. Despite the absence of a CO2 effect on individual leaf expansion or specific growth rate (SGR), increasing the CO2 concentration to ambient +150 or +300 cm3 m−3 decreased SRR by 28 to 45% compared with ambient-grown controls. These lower leaf Respiration rates were correlated with reduced leaf nitrogen concentrations. As described by the two-component model of growth and Maintenance Respiration, SRR was a linear function of SGR. Ambient-grown leaves had a growth Respiration coefficient of 704 mg CO2 g−1 dry mass compared with 572 and 570 mg CO2 g−1 for leaves grown at the two higher CO2 concentrations. Leaves from the elevated CO2 treatments had an average Maintenance Respiration coefficient of 88 mg CO2 g−1 dry mass d−1 compared with 135 mg CO2 g−1 d −1 for leaves from the ambient treatment. Incorporating these growth and Maintenance coefficients into a leaf growth simulation model indicated that total Respiration would be reduced by 21 to 26 % for a leaf exposed to + 150 or + 300 cm3 m−3 CO2 throughout its 50-d lifespan compared with one grown at ambient CO2 conditions. Reductions in total Respiration were dominated by a lower rate of Maintenance Respiration, while the contribution of a lower specific rate of growth Respiration was largely offset by a greater dry mass for leaves grown at elevated CO2 concentrations. Although reductions in the respiratory loss of carbon could be beneficial, Respiration is unlikely to decrease without a concomitant decrease in other metabolic processes. Whether these reductions are beneficial or detrimental to the long-term growth of plants exposed to elevated CO2 remains unresolved.
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Growth and Maintenance Respiration in leaves of Liriodendron tulipifera L. exposed to long‐term carbon dioxide enrichment in the field
New Phytologist, 1992Co-Authors: Stan D Wullschleger, Richard J Norby, Carla A GundersonAbstract:summary Specific Respiration rate (SRR) was mathematically partitioned into its growth and Maintenance components for leaves of yellow-poplar (Liriodendron tulipifera L.) after 3 yr of CO2 enrichment in open-top field chambers. Despite the absence of a CO2 effect on individual leaf expansion or specific growth rate (SGR), increasing the CO2 concentration to ambient +150 or +300 cm3 m−3 decreased SRR by 28 to 45% compared with ambient-grown controls. These lower leaf Respiration rates were correlated with reduced leaf nitrogen concentrations. As described by the two-component model of growth and Maintenance Respiration, SRR was a linear function of SGR. Ambient-grown leaves had a growth Respiration coefficient of 704 mg CO2 g−1 dry mass compared with 572 and 570 mg CO2 g−1 for leaves grown at the two higher CO2 concentrations. Leaves from the elevated CO2 treatments had an average Maintenance Respiration coefficient of 88 mg CO2 g−1 dry mass d−1 compared with 135 mg CO2 g−1 d −1 for leaves from the ambient treatment. Incorporating these growth and Maintenance coefficients into a leaf growth simulation model indicated that total Respiration would be reduced by 21 to 26 % for a leaf exposed to + 150 or + 300 cm3 m−3 CO2 throughout its 50-d lifespan compared with one grown at ambient CO2 conditions. Reductions in total Respiration were dominated by a lower rate of Maintenance Respiration, while the contribution of a lower specific rate of growth Respiration was largely offset by a greater dry mass for leaves grown at elevated CO2 concentrations. Although reductions in the respiratory loss of carbon could be beneficial, Respiration is unlikely to decrease without a concomitant decrease in other metabolic processes. Whether these reductions are beneficial or detrimental to the long-term growth of plants exposed to elevated CO2 remains unresolved.
