共查询到20条相似文献,搜索用时 31 毫秒
1.
K. Kuokkanen P. Niemelä J. Matala R. Julkunen-Tiitto† J. Heinonen‡ M. Rousi§ H. Henttonen¶ J. Tahvanainen† S. Kellomäki 《Global Change Biology》2004,10(9):1504-1512
The effects of elevated CO2 and temperature on the resource allocation pattern and resistance against mammalian herbivores of silver birch (Betula pendula Roth) were studied. Birch seedlings were grown through two growing seasons in closed‐top chambers exposed to four different treatments: ambient CO2 and temperature, elevated atmospheric CO2 (700 ppm) and ambient temperature, elevated temperature (+3°C above ambient) and ambient CO2, and a combination of elevated CO2 and temperature. After winter hardening of the seedlings, the growth of the seedlings was measured and the concentration of secondary compounds such as phenolics and papyriferic acid determined. The top parts of the stem were fed to hares, and the basal parts of the same stems were offered to voles. Elevated CO2 increased the height and basal diameter of the shoots, shoot biomass and total biomass of the seedlings but did not have any effect on secondary chemistry. Elevated temperature increased the height and shoot biomass, but did not have a significant effect on the total biomass of the seedlings. Elevated temperature decreased the concentration of condensed tannins and their precursor, (+)‐catechin, in the top part of the stems, but only the concentration of (+)‐catechin in the basal part of the stems. There were no significant interactive effects between CO2 and temperature on phenolics in the stems, while the concentration of papyriferic acid showed significant interaction in the top part of the stems. This indicates high accumulation of papyriferic acid in ambient CO2 under increased temperature. Consequently, elevated temperature increased the resistance of birch against hares, but did not affect the resistance of the basal parts of the same birches to voles. Our results indicate that the predicted climatic change will not necessarily lead to increased browsing damage by the mountain hare and the field vole to silver birch. 相似文献
2.
This study examined the effects of elevated CO2 on secondary metabolites for saplings of tropical trees. In the first experiment, nine species of trees were grown in the ground in open-top chambers in central Panama at ambient and elevated CO2 (about twice ambient). On average, leaf phenolic contents were 48% higher under elevated CO2. Biomass accumulation was not affected by CO2, but starch, total non-structural carbohydrates and C/N ratios all increased. In a second experiment with Ficus, an early successional species, and Virola, a late successional species, treatments were enriched for both CO2 and nutrients. For both species, nutrient fertilization increased plant growth and decreased leaf carbohydrates, C/N ratios and phenolic contents, as predicted by the carbon/nutrient balance hypothesis. Changes in leaf C/N levels were correlated with changes in phenolic contents for Virola (r=0.95, P<0.05), but not for Ficus. Thus, elevated CO2, particularly under conditions of low soil fertility, significantly increased phenolic content as well as the C/N ratio of leaves. The magnitude of the changes is sufficient to negatively affect herbivore growth, survival and fecundity, which should have impacts on plant/herbivore interactions. 相似文献
3.
Seed production and seedling recruitment were measured over 2 years under ambient (360 ppm) and elevated (475 ppm) atmospheric CO2 in a free air carbon dioxide enrichment (FACE) experiment, carried out in a sheep-grazed pasture on dry, sandy soil in New Zealand. In both years elevated CO2 led to more dispersed seeds of the grasses Anthoxanthum odoratum, Lolium perenne and Poa pratensis, the legumes Trifolium repens and T. subterraneum and the herbs Hypochaeris radicata and Leontodon saxatilis. The increased seed dispersal in A. odoratum, H. radicata, Leontodon saxatilis and T. repens reflected both more inflorescences per unit area and more seeds per inflorescence under elevated CO2. The increased seed dispersal in Lolium perenne, P. pratensis and T. subterraneum was due solely to more inflorescences per unit area. The number of seedlings that emerged and survived to at least 7 months of age was increased by elevated CO2 for H. radicata, Leontodon saxatilis, T. repens and T. subterraneum in both years and for A. odoratum and Lolium perenne in the first year. For species where increased seedling recruitment was noted, there was a significant positive correlation between seed production in summer and seedling emergence in the following autumn and winter, and sowing 200 extra seeds per species m-2 resulted in more seedlings compared to unsown controls. Elevated CO2 did not affect seedling survival in any species. There was no measurable effect of elevated CO2 on canopy and soil surface conditions or soil moisture at the time of seedling emergence. The results suggest the dominant effect of elevated CO2 on seedling recruitment in this pasture was an indirect one, reflecting effects on the number of seeds produced. The biomass of H. radicata, Leontodon saxatilis, T. repens and T. subterraneum in the above-ground vegetation was greater under elevated than ambient CO2. However, the size of individual seedlings and mature plants of these four species was unaffected by elevated CO2. The results indicate an important way elevated CO2 influenced plant species composition in this pasture was through changes in the pattern of seedling recruitment. 相似文献
4.
Abstract 1 The effect of elevated CO2 and temperature on the foliar chemistry Betula pendula Roth and the feeding performance of polyphagous weevils Phyllobius maculicornis Germ. was studied. Birch seedlings were grown during one growing season in chamber‐less field conditions and in closed‐top chambers exposed to four different treatments: ambient CO2 (350 p.p.m) and temperature, elevated atmospheric CO2 (700 p.p.m) and ambient temperature, elevated temperature +3 °C above ambient) and ambient CO2, and a combination of elevated CO2 and temperature. 2 In leaves under CO2 enrichment, the concentration of nitrogen and some flavonol glycosides significantly decreased, whereas the concentration of total phenolics, condensed tannins and (+)‐catechin significantly increased. The total concentration of cinnamoylquinic acids was significantly increased by CO2 and decreased by temperature. The concentration of salidroside increased under elevated temperature. 3 Weevil‐feeding experiments were carried out in a five‐choice arrangement, one leaf from each of the five treatments (chamber‐less field controls and four different treatments in chambers) being placed in random order in a plastic box. The weevils preferred the leaves grown under elevated CO2, which had low nitrogen, high phenolics and the highest condensed tannin concentrations. Whether the reason for this trend is due to the stimulating effect of condensed tannins and/or a change in other secondary compounds, remains unknown. The weevils did not show any obviously different response in feeding performance to temperature and the combination of elevated CO2 and temperature. 相似文献
5.
Jarkko Utriainen Sari Janhunen Heljä-Sisko Helmisaari Toini Holopainen 《Trees - Structure and Function》2000,14(8):475-484
Three-year-old Scots pine (Pinus sylvestris L.) seedlings were exposed to ambient or elevated ozone (O3) (1.52ambient) and carbon dioxide (CO2) (590 µmol mol-1) concentrations during two growing seasons in open-top field chambers (OTCs). Five different treatments were applied in the chambers: filtered air, ambient air, elevated O3, elevated CO2, and elevated O3 and CO2 combined. Ambient plots outside the OTCs were also included, but the chamber ambient was used as a control in O3 and CO2 treatments due to a significant chamber effect. Increases in yellowing and chlorotic mottling of previous-year (C+1) needles and in the amount of cytoplasmic ribosomes and electron density of the chloroplast stroma in current-year (C) and C+1 needle mesophyll cells were observed in elevated O3 at both CO2 concentrations. Elevated O3 alone caused a non-significant 10.9% decrease in plant total dry mass and a significant decrease in manganese (Mn) content of C needles. CO2 enrichment caused a significant increase in needle cross-sectional width after the first year of exposure, and an accumulation of starch and slight curling and swelling of the chloroplast thylakoids in the mesophyll tissue of C needles after the second year of exposure. Calcium and Mn contents were increased and copper and nitrogen contents were decreased, significantly, in CO2-exposed needles. A non-significant 19.1% increase in plant total dry mass was measured in elevated CO2 alone, whereas a 14.8% reduction in total dry mass, together with a significant reduction in current-year main shoot length, was found in the combined treatment. Overall, in spite of decreases in O3-induced visible injuries by CO2, elevated CO2 levels were not able to counteract the impact of O3 in this experiment. 相似文献
6.
David Olszyk Martha Apple Barbara Gartner Rachel Spicer Claudia Wise Erica Buckner Annick Benson-Scott David Tingey 《Trees - Structure and Function》2005,19(5):552-563
Seedling structure influences tree structure and function, ultimately determining the potential productivity of trees and their competitiveness for resources. We investigated changes in shoot structure for seedlings of Pseudotsuga menziesii (Douglas-fir) grown under climate change scenarios of ambient or elevated CO2 (+180 mol mol–1) plus ambient or elevated temperature (+3.5°C), for 4 years in outdoor, sunlit chambers. Mass allocation and allometry were measured for buds, leaves, branches, and stems, and anatomy was evaluated for leaves and stems. Seedlings became more xeromorphic with elevated temperature: allocation of total mass to branches over stems and leaves increased, sapwood area to height ratio increased, number of growing points relative to seedling size increased, and stem and branch length and mass decreased for sections initiated during the three full CO2 and temperature seasons. Neither stem nor leaf anatomy was affected by elevated temperature. Elevated CO2 increased specific mass of leaves, but had few other effects on mass allocation, allometry, or anatomy for any shoot organ. There were no CO2 × temperature interactions for any important parameter. Thus, under realistic simulated field environmental conditions representative for in at least some P. menziesii forests (i.e., OR, USA, forests with limited soil nitrogen and summer soil moisture), elevated temperature, but not elevated CO2, may affect seedling shoot structure and, hence, function. 相似文献
7.
Hee-Myong Ro Pan-Gi Kim In-Bog Lee Myoung-Soon Yiem Su-Young Woo 《Trees - Structure and Function》2001,15(4):195-203
Growth and photosynthetic responses of dwarf apple saplings (Malus domestica Borkh. cv. Fuji) acclimated to 3 years of exposure to contrasting atmospheric CO2 concentrations (360 and 650 µmol mol-1) in combination with current ambient or elevated (ambient +5°C) temperature patterns were determined. Four 1-year-old apple saplings grafted onto M.9 rootstocks were each enclosed in late fall 1997 in a controlled environment unit in nutrient-optimal soil. Soil moisture regimes were automatically controlled by drip irrigation scheduled at 50 kPa of soil moisture tension. For the elevated CO2 concentration alone, overall tree growth was suppressed. However, tree growth was slightly enhanced when warmer temperatures were combined with the elevated CO2 concentration. Neither temperature nor CO2 concentration affected leaf chlorophyll content and stomatal density. The elevated CO2 concentration decreased mean leaf area, but increased starch accumulation, thus resulting in a higher specific dry mass of leaves. An elevated temperature reduced starch accumulation. Light-saturated rates of leaf photosynthesis were suppressed due to the elevated CO2 concentration, but this effect was removed or enhanced with warmer temperatures. The elevated CO2 concentration increased the optimum temperature for photosynthesis by ca. 4°C, while the warmer temperature did not. The results of this study suggested that the long-term adaptation of apple saplings to growth at an elevated CO2 concentration may be associated with a potential for increased growth and productivity, if a doubling of the CO2 concentration also leads to elevated temperatures. 相似文献
8.
The effect of elevated carbon dioxide and ozone on leaf- and branch-level photosynthesis and potential plant-level carbon gain in aspen 总被引:7,自引:0,他引:7
Asko Noormets Evan P. McDonald Richard E. Dickson Eric L. Kruger Anu Sôber J. Isebrands David F. Karnosky 《Trees - Structure and Function》2001,15(5):262-270
Two aspen (Populus tremuloides Michx.) clones, differing in O3 tolerance, were grown in a free-air CO2 enrichment (FACE) facility near Rhinelander, Wisconsin, and exposed to ambient air, elevated CO2, elevated O3 and elevated CO2+O3. Leaf instantaneous light-saturated photosynthesis (PS) and leaf areas (A) were measured for all leaves of the current terminal, upper (current year) and the current-year increment of lower (1-year-old) lateral branches. An average, representative branch was chosen from each branch class. In addition, the average photosynthetic rate was estimated for the short-shoot leaves. A summing approach was used to estimate potential whole-plant C gain. The results of this method indicated that treatment differences were more pronounced at the plant- than at the leaf- or branch-level, because minor effects within modules accrued in scaling to plant level. The whole-plant response in C gain was determined by the counteracting changes in PS and A. For example, in the O3-sensitive clone (259), inhibition of PS in elevated O3 (at both ambient and elevated CO2) was partially ameliorated by an increase in total A. For the O3-tolerant clone (216), on the other hand, stimulation of photosynthetic rates in elevated CO2 was nullified by decreased total A. 相似文献
9.
Forest carbon balance under elevated CO2 总被引:10,自引:2,他引:8
Jason G. Hamilton Evan H. DeLucia Kate George Shawna L. Naidu Adrien C. Finzi William H. Schlesinger 《Oecologia》2002,131(2):250-260
Free-air CO2 enrichment (FACE) technology was used to expose a loblolly pine (Pinus taeda L.) forest to elevated atmospheric CO2 (ambient + 200 µl l-1). After 4 years, basal area of pine trees was 9.2% larger in elevated than in ambient CO2 plots. During the first 3 years the growth rate of pine was stimulated by ~26%. In the fourth year this stimulation declined to 23%. The average net ecosystem production (NEP) in the ambient plots was 428 gC m-2 year-1, indicating that the forest was a net sink for atmospheric CO2. Elevated atmospheric CO2 stimulated NEP by 41%. This increase was primarily an increase in plant biomass increment (57%), and secondarily increased accumulation of carbon in the forest floor (35%) and fine root increment (8%). Net primary production (NPP) was stimulated by 27%, driven primarily by increases in the growth rate of the pines. Total heterotrophic respiration (Rh) increased by 165%, but total autotrophic respiration (Ra) was unaffected. Gross primary production was increased by 18%. The largest uncertainties in the carbon budget remain in separating belowground heterotrophic (soil microbes) and autotrophic (root) respiration. If applied to temperate forests globally, the increase in NEP that we measured would fix less than 10% of the anthropogenic CO2 projected to be released into the atmosphere in the year 2050. This may represent an upper limit because rising global temperatures, land disturbance, and heterotrophic decomposition of woody tissues will ultimately cause an increased flux of carbon back to the atmosphere. 相似文献
10.
The long-term effects of elevated CO2 and CO2+O3 concentrations on the growth allocation in northern provenances of Norway spruce [Picea abies (L.) Karst.], Scots pine [Pinus sylvestris (L.)] and pubescent birch clones (Betula pubescens Ehrh.) were examined in open-top chambers after a 4-year-long experiment. The total biomass responses of the tree seedlings to increased CO2 and CO2+O3 concentrations were not statistically significant and varied between the provenances and species. The seedlings of northern origin were the least sensitive in their response to treatments. The total biomass of the Norway spruce seedlings slightly decreased in response to CO2 in three provenances. Scots pine from the local provenance had a slight biomass increase after elevated CO2+O3 treatment. The slower-growing birch clone seemed to benefit from elevated CO2, whereas in the faster-growing clone, reductions in biomass accumulation were seen. The combined CO2+O3 treatment reduced the positive effects of elevated CO2, especially in the slower-growing birches. Observations of significant effects were limited to a few parameters. Carbon dioxide treatment decreased needle dry weight of Norway spruce in one northern provenance. The needle and wood dry weight increased (CO2 + O3) in local Scots pine. Significant birch response was limited to increased fine root density (O3 + CO2) in the inland clone. The diverse effects of elevated CO2 and CO2 +O3 on seedling growth and biomass provide evidence that exposure of northern trees to the enhanced variable CO2 and O3 concentrations of the future will have varied effects on the growth of these species. The direction and magnitude of those effects will differ depending on species and origins. 相似文献
11.
The effects of sink capacity on the regulation of the acclimationof photosynthetic capacity to elevated levels of carbon dioxideare important from a global perspective. We investigated theeffeocts of elevated (750 µmol mol1) and ambient(350 µmol mol1) atmospheric CO2 on growth, carbohydratelevels, and photosynthesis in radish seedlings from 15 to 46d after planting. In radish, a major sink is the storage root,and its thickening is initiated early. Elevated CO2 increasedthe accumulation of dry matter by 111% but had no effect onthe acclimation of the rate of photosynthesis or on the levelsof carbohydrates in leaves at dawn. Elevated CO2 increased thedry weight in storage roots by 105% by 46 d after planting,apparently enhancing the sink capacity. This enhanced capacityseemed to be responsible for absorption of elevated levels ofphotosynthate and to result in the absence of any over-accumulationof carbohydrates in source leaves and the absence of negativeacclimation of photosynthetic capacity at the elevated levelof CO2. (Received July 4, 1997; Accepted October 16, 1997) 相似文献
12.
Annual and short-lived perennial plant performance during wet years is important for long-term persistence in the Mojave Desert. Additionally, the effects of elevated CO2 on desert plants may be relatively greater during years of high resource availability compared to dry years. Therefore, during an El Niño year at the Nevada Desert FACE Facility (a whole-ecosystem CO2 manipulation), we characterized photosynthetic investment (by assimilation rate-internal CO2 concentration relationships) and evaluated the seasonal pattern of net photosynthesis (Anet) and stomatal conductance (gs) for an invasive annual grass, Bromus madritensis ssp. rubens and a native herbaceous perennial, Eriogonum inflatum. Prior to and following flowering, Bromus showed consistent increases in both the maximum rate of carboxylation by Rubisco (VCmax) and the light-saturated rate of electron flow (Jmax) at elevated CO2. This resulted in greater Anet at elevated CO2 throughout most of the life cycle and a decrease in the seasonal decline of maximum midday Anet upon flowering as compared to ambient CO2. Eriogonum showed significant photosynthetic down-regulation to elevated CO2 late in the season, but the overall pattern of maximum midday Anet was not altered with respect to phenology. For Eriogonum, this resulted in similar levels of Anet on a leaf area basis as the season progressed between CO2 treatments, but greater photosynthetic activity over a typical diurnal period. While gs did not consistently vary with CO2 in Bromus, it did decrease in Eriogonum at elevated CO2 throughout much of the season. Since the biomass of both plants increased significantly at elevated CO2, these patterns of gas exchange highlight the differential mechanisms for increased plant growth. The species-specific interaction between CO2 and phenology in different growth forms suggests that important plant strategies may be altered by elevated CO2 in natural settings. These results indicate the importance of evaluating the effects of elevated CO2 at all life cycle stages to better understand the effects of elevated CO2 on whole-plant performance in natural ecosystems. 相似文献
13.
Microbial community composition and function beneath temperate trees exposed to elevated atmospheric carbon dioxide and ozone 总被引:11,自引:0,他引:11
We hypothesized that changes in plant growth resulting from atmospheric CO2 and O3 enrichment would alter the flow of C through soil food webs and that this effect would vary with tree species. To test this idea, we traced the course of C through the soil microbial community using soils from the free-air CO2 and O3 enrichment site in Rhinelander, Wisconsin. We added either 13C-labeled cellobiose or 13C-labeled N-acetylglucosamine to soils collected beneath ecologically distinct temperate trees exposed for 3 years to factorial CO2 (ambient and 200 µl l-1 above ambient) and O3 (ambient and 20 µl l-1 above ambient) treatments. For both labeled substrates, recovery of 13C in microbial respiration increased beneath plants grown under elevated CO2 by 29% compared to ambient; elevated O3 eliminated this effect. Production of 13C-CO2 from soils beneath aspen (Populus tremuloides Michx.) and aspen-birch (Betula papyrifera Marsh.) was greater than that beneath aspen-maple (Acer saccharum Marsh.). Phospholipid fatty acid analyses (13C-PLFAs) indicated that the microbial community beneath plants exposed to elevated CO2 metabolized more 13C-cellobiose, compared to the microbial community beneath plants exposed to the ambient condition. Recovery of 13C in PLFAs was an order of magnitude greater for N-acetylglucosamine-amended soil compared to cellobiose-amended soil, indicating that substrate type influenced microbial metabolism and soil C cycling. We found that elevated CO2 increased fungal activity and microbial metabolism of cellobiose, and that microbial processes under early-successional aspen and birch species were more strongly affected by CO2 and O3 enrichment than those under late-successional maple. 相似文献
14.
Scots pine (Pinus sylvestris L.) seedlings were grown for 3years in the ground in open top chambers and exposed to twoconcentrations of atmospheric CO2(ambient or ambient + 400 µmol mol-1) without addition of nutrients and water. Biomassproduction (above-ground and below-ground) and allocation, aswell as canopy structure and tissue nitrogen concentrationsand contents, were examined by destructive harvest after 3 years.Elevated CO2increased total biomass production by 55%, reducedneedle area and needle mass as indicated, respectively, by lowerleaf area ratio and leaf mass ratio. A relatively smaller totalneedle area was produced in relation to fine roots under elevatedCO2. The proportion of dry matter in roots was increased byelevated CO2, as indicated by increased root-to-shoot ratioand root mass ratio. Within the root system, there was a significantshift in the allocation towards fine roots. Root litter constituteda much higher fraction of fine roots in trees grown in the elevatedCO2than in those grown in ambient CO2. Growth at elevated CO2causeda significant decline in nitrogen concentration only in theneedles, while nitrogen content significantly increased in branchesand fine roots (with diameter less than 1 mm). There were nochanges in crown structure (branch number and needle area distribution).Based upon measurements of growth made throughout the 3 years,the greatest increase in biomass under elevated CO2took placemainly at the beginning of the experiment, when trees grownin elevated CO2had higher relative growth rates than those grownunder ambient CO2; these differences disappeared with time.Symptoms of acclimation of trees to growth in the elevated CO2treatmentwere observed and are discussed. Copyright 2000 Annals of BotanyCompany Elevated CO2, Pinus sylvestris, biomass production, allocation, fine roots, root litter, crown structure, nitrogen, C/N ratio 相似文献
15.
Tree seedling growth in natural deep shade: functional traits related to interspecific variation in response to elevated CO2 总被引:1,自引:0,他引:1
Stephan Hättenschwiler 《Oecologia》2001,129(1):31-42
The mechanisms for species-specific growth responses to changes in atmospheric CO2 concentration within narrow ecological groups of species, such as shade-tolerant, late-successional trees, have rarely been addressed and are not well understood. In this study the underlying functional traits for interspecific variation in the biomass response to elevated CO2 were explored for seedlings of five late-successional temperate forest tree species (Fagus sylvatica, Acer pseudoplatanus, Quercus robur, Taxus baccata, Abies alba). The seedlings were grown in the natural forest understorey in very low and low light microsites (an average of 1.3% and 3.4% full sun in this experiment), and were exposed to either current ambient CO2 concentrations, 500, or 660 µl CO2 l-1 in 36 open-top chambers (OTC) over two growing seasons. Even across the narrow range of successional status and shade tolerance, the study species varied greatly in photosynthesis, light compensation point, leaf dark respiration (Rd), leaf nitrogen concentration, specific leaf area (SLA), leaf area ratio (LAR), and biomass allocation among different plant parts, and showed distinct responses to CO2 in these traits. No single species combined all characteristics traditionally considered as adaptive to low light conditions. At very low light, the CO2 stimulation of seedling biomass was related to increased LAR and decreased Rd, responses that were observed only in Fagus and Taxus. At slightly higher light levels, interspecific differences in the biomass response to elevated CO2 were reversed and correlated best with leaf photosynthesis. The data provided here contribute to a mechanistic process-based understanding of distinct response patterns in co-occurring tree species to elevated CO2 in natural deep shade. I conclude that the high variation in physiological and morphological traits among late-successional species, and the consequences for their responses to slight changes in resource availability, have previously been underestimated. The commonly used broad definitions of functional groups of species may not be sufficient for the understanding of recruitment success and dynamic changes in species composition of old-growth forests in response to rising concentrations of atmospheric CO2. 相似文献
16.
Genotypic variation in the response of two perennial grass species to elevated carbon dioxide 总被引:3,自引:0,他引:3
Shoot and reproductive biomass of genotypes of Bromus erectus and Dactylis glomerata grown in competition at ambient and elevated CO2 were examined for 2 consecutive years in order to test whether genetic variation in those traits exists and whether it is maintained over time. At the species level, a positive CO2 response of shoot biomass of both species was only found in the first year of treatment. At the genotype level, no significant CO22genotype interaction was found at any single harvest either for vegetative or reproductive biomass of either species. Analysis over time, however, indicated that there is a potential for evolutionary adaptation only for D. glomerata: (1) repeated measures ANOVA detected a marginally significant CO22genotype2time interaction for shoot biomass, because the range of the genotypes CO2 response increased over time; (2) genotypes that displayed the highest response during the first year under elevated CO2 also showed the highest response the second year. Null (B. erectus) or weak (D. glomerata) selective potentials of elevated CO2 were detected in this experiment, but short time series could underestimate this potential with perennial species. 相似文献
17.
Jean-Fran?ois David Nathalie Malet Marie-Madeleine Co?teaux Jacques Roy 《Oecologia》2001,127(3):343-349
The consumption and assimilation rates of the woodlouse Armadillidium vulgare were measured on leaf litters from five herb species grown and naturally senesced at 350 and 700 µl l-1 CO2. Each type of litter was tested separately after 12, 30 and 45 days of decomposition at 18°C. The effects of elevated CO2 differed depending on the plant species. In Medicago minima (Fabaceae), the CO2 treatment had no significant effect on consumption and assimilation. In Tyrimnus leucographus (Asteraceae), the CO2 treatment had no significant effect on consumption, but the elevated CO2 litter was assimilated at a lower rate than the ambient CO2 litter after 30 days of decomposition. In the three other species, Galactites tomentosa (Asteraceae), Trifolium angustifolium (Fabaceae) and Lolium rigidum (Poaceae), the elevated CO2 litter was consumed and/or assimilated at a higher rate than the ambient CO2 litter. Examination of the nitrogen contents in these three species of litter did not support the hypothesis of compensatory feeding, i.e. an increase in woodlouse consumption to compensate for low nitrogen content of the food. Rather, the results suggest that in herbs that were unpalatable at the start of the experiment (Galactites, Trifolium and Lolium), more of the the litter produced at 700 µl l-1 CO2 was consumed than of that produced at 350 µl l-1 because inhibitory factors were eliminated faster during decomposition. 相似文献
18.
KURSCHNER WOLFRAM M.; STULEN INEKE; WAGNER FRIEDERIKE; KUIPER PIETER J. C. 《Annals of botany》1998,81(5):657-664
To test whether stomatal density measurements on oak leaf remainsare reliable tools for assessing palaeoatmospheric carbon dioxideconcentration [CO2], under changing Late Miocene palaeoenvironmentalconditions, young seedings of oak (Quercus petraea,Liebl.) weregrown at elevatedvs.ambient atmospheric [CO2] and at high humiditycombined with an increased air temperature. The leaf anatomyof the young oaks was compared with that of fossil leaves ofthe same species. In the experiments, stomatal density and stomatalindex were significantly decreased at elevated [CO2] in comparisonto ambient [CO2]. Elevated [CO2] induced leaf cell expansionand reduced the intercellular air space by 35%. Leaf cell sizeor length were also stimulated at high air humidity and temperature.Regardless of a temperate or subtropical palaeoclimate, leafcell size in fossil oak was not enhanced, since neither epidermalcell density nor length of the stomatal apparatus changed. Theabsence of these effects may be attributed to the phenologicalresponse of trees to climatic changes that balanced temporalchanges in environmental variables to maintain leaf growth underoptimal and stable conditions.Quercus petraea,which evolvedunder recurring depletions in the palaeoatmospheric [CO2], maypossess sufficient phenotypic plasticity to alter stomatal frequencyin hypostomatous leaves allowing high maximum stomatal conductanceand high assimilation rates during these phases of low [CO2].Copyright1998 Annals of Botany Company Atmospheric CO2, high humidity, elevated temperature,Quercus petraea,durmast oak, Late Miocene, palaeoclimates, leaf anatomy, stomatal density, stomatal index 相似文献
19.
Kutk Jaromr; Ntr Lubomr; Demmers-Derks H.H.; Lawlor David W. 《Journal of experimental botany》1995,46(12):1797-1802
Sugar beet (Beta vulgaris L., cultivar Celt) plants were grownunder simulated field conditions in pots and supplied with adequateor deficient nitrogen (HN and LN, respectively) combined withtwo CO2 concentrations, ambient (c. 350µmol mol1C02AC), or elevated CO2 (c. 600 µmol mol1CO2HC). Chloroplast structure in mesophyll palisade cellsof mature leaves (leaf number 19 in HN and 9 in LN), sampledat midday on 16 August 1993 was studied by transmission electronmicroscopy and quantified stereologically. The ultrastructureof palisade parenchyma chloroplasts was affected by the elevatedCO2 concentration and strikingly affected by nitrogen supply.Chloroplast diameter (cross-sectional length) was slightly,but not significantly, greater in HC than AC treatments withinan N treatment, but was smaller in LN than HN; chloroplast cross-sectionalarea also increased with HC in both N treatments, but only significantlyso in LN. Elevated CO2 reduced the proportion of total thylakoids(significant at 5% and 0.1% in HN and LN, respectively) dueto decreased granal thylakoids, but the proportion of inter-granal(stromal) thylakoid membranes was not affected compared to chloroplastsfrom plants grown with ambient CO2. Chloroplast stroma increasedas a proportion of chloroplast volume with elevated comparedto ambient CO2 with HN but not LN. Starch inclusions were notsignificantly different with elevated compared to ambient CO2at HN, but the proportion of starch increased considerably atelevated compared to ambient C02 at LN, indicating an over-productionof assimilates. Plastoglobuli in chloroplasts increased withdeficient N, but decreased with elevated CO2. Larger chloroplastswith a greater proportion of stroma, but a smaller proportionof granal thylakoids, suggest increased CO2 assimilating capacityand decreased light harvesting/PSII capacity with elevated CO2. Key words: Chloroplast, ultrastructure, elevated CO2 concentration, nitrogen deficiency, sugar beet, Beta vulgaris 相似文献
20.
The growth (fresh weight), morphogenesis (leaves, roots and shoots) and essential oil composition of mint (Mentha sp. L.) and thyme (Thymus vulgaris L.) plants were determined after 8 weeks under 350, 1,500, 3,000, 10,000 and 30,000 µmol mol-1 CO2. Plants were grown in vitro on basal medium (BM) consisting of Murashige and Skoog salts and 0.8% agar that contained either 0 or 3% sucrose under a 16-h (day)/8-h (night) photoperiod at a light intensity of 180 µmol s-1 m-2 or in soil in a greenhouse under conditions of natural sunlight. Ultra-high CO2 levels (i.e. ́,000 µmol mol-1 CO2) substantially increased fresh weights, leaves, shoots and roots for all plants compared to plants grown under ambient air (350 µmol mol-1 CO2) both in vivo and in vitro. For both species, 10,000 µmol mol-1 CO2 was the optimum concentration to obtain the largest growth and morphogenesis responses under in vitro conditions, while the 3,000- to 10,000-µmol mol-1 CO2 range provided the largest yields for soil-grown plants. Essential oil composition (i.e. monoterpenes, piperitonone oxide and limonene from mint and aromatic phenol and thymol from thyme) from the shoot portion of plants grown at all CO2 levels was analyzed in CH2Cl2 extracts via gas chromatography. Higher levels of secondary compounds occurred in vitro when cultures were grown under ultra-high CO2 levels than in ambient air. The concentration of thymol, a major secondary compound in thyme plants grown on BM containing sucrose, was 317-fold higher at 10,000 µmol mol-1 CO2 than in plants grown under ambient air conditions with the same BM. The levels of secondary compound in in-vitro-grown plantlets exposed to ultra-high CO2 concentrations exceeded those occurring in plants grown in the greenhouse under the same CO2 levels. Substantially higher levels of secondary compound occurred in plants under ultra-high CO2 levels on BM containing sucrose than on BM lacking sucrose or in soil. Thymol levels in thyme plants grown on BM containing sucrose were 3.9-fold higher at 10,000 µmol mol-1 CO2 than in shoots grown on BM without sucrose under the same CO2 levels. High positive correlations occurred between thymol concentrations and CO2 levels, fresh weights, shoots, roots and leaves when thyme shoots were grown on BM with sucrose. High positive correlations for thyme shoots grown on BM without sucrose only occurred between thymol concentrations and CO2 levels, fresh weights, shoots and leaves. No positive correlations between thymol concentrations and CO2 levels or any growth or morphogenesis responses occurred for thyme shoots when grown in soil. 相似文献