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1.
The effects of elevated CO2 on plant biomass and community structure have been studied for four seasons in a calcareous grassland in northwest Switzerland.
This highly diverse, semi-natural plant community is dominated by the perennial grass Bromus erectus and is mown twice a year to maintain species composition. Plots of 1.3 m2 were exposed to ambient or elevated CO2 concentrations (n = 8) using a novel CO2 exposure technique, screen-aided CO2 control (SACC) starting in March 1994. In the 1st year of treatment, the annual harvested biomass (sum of aboveground biomass
from mowings in June and October) was not significantly affected by elevated CO2. However, biomass increased significantly at elevated CO2 in the 2nd (+20%, P = 0.05), 3rd (+21%, P = 0.02) and 4th years (+29%, P = 0.02). There were no detectable differences in root biomass in the top 8 cm of soil between CO2 treatments on eight out of nine sampling dates. There were significant differences in CO2 responsiveness between functional groups (legumes, non-leguminous forbs, graminoids) in the 2nd (P = 0.07) and 3rd (P < 0.001) years of the study. The order of CO2 responsiveness among functional groups changed substantially from the 2nd to the 3rd year; for example, non-leguminous forbs
had the smallest relative response in the 2nd year and the largest in the 3rd year. By the 3rd year of CO2 exposure, large species-specific differences in CO2 response had developed. For five important species or genera the order of responsiveness was Lotus corniculatus (+271%), Carex flacca (+249%), Bromus erectus (+33%), Sanguisorba minor (no significant CO2 effect), and six Trifolium species (a negative response that was not significant). The positive CO2 responses in Bromus and Carex were most closely related to increases in tiller number. Species richness was not affected by CO2 treatment, but species evenness increased under elevated CO2 (modified Hill ratio; P = 0.03) in June of the 3rd year, resulting in a marginally significant increase in species diversity (Simpson's index; P = 0.09). This and other experiments with calcareous grassland plants show that elevated atmospheric CO2 concentrations can substantially alter the structure of calcareous grassland communities and may increase plant community
biomass.
Received: 12 July 1997 / Accepted: 14 September 1998 相似文献
2.
Travis E. Huxman Erik P. Hamerlynck Dean N. Jordan Katrina J. Salsman Stanley D. Smith 《Oecologia》1998,114(2):202-208
Seeds were collected and compared from parent plants of Bromusrubens L. (Poaceae), an exotic Mojave Desert annual grass, grown in ambient (360 μmol mol−1) and elevated (700 μmol mol−1) CO2 to determine if parental CO2 growth conditions affected seed quality. Performance of seeds developed on the above plants was evaluated to determine the
influence of parental CO2 growth conditions on germination, growth rate, and leaf production. Seeds of B. rubens developed on parents grown in elevated CO2 had a larger pericarp surface area, higher C:N ratio, and less total mass than ambient-developed seeds. Parental CO2 environment did not have an effect on germination percentage or mean germination time, as determined by radicle emergence.
Seedlings from elevated-CO2-developed seeds had a reduced relative growth rate and achieved smaller final mass over the same growth period. Elevated-CO2-developed seeds had smaller seed reserves than ambient seeds, as determined by growing seedlings in sterile media and monitoring
senescence. It appears that increased seed C:N ratios associated with plants grown under elevated CO2 may have a major effect on seed quality (morphology, nutrition) and seedling performance (e.g., growth rate and leaf production).
Since the invasive success of B. rubens is primarily due to its ability to rapidly germinate, increase leaf area and maintain a relatively high growth rate compared
to native annuals and perennial grasses, reductions in seed quality and seedling performance in elevated CO2 may have significant impacts on future community composition in the Mojave Desert.
Received: 11 April 1997 / Accepted: 20 November 1997 相似文献
3.
Seedlings of Eucalyptus tereticornis (Smith) were grown under two levels of availability each of CO2 (352 and 793 μmol mol−1), soil nutrients (1/24 and 1/4 Hoagland’s solution) and light (full and 30% sunlight). Low soil nutrient availability or
high light increased the C:N ratio of leaves, leading to lower leaf nitrogen concentrations, higher leaf specific weights
and higher levels of both total phenolics and condensed tannins. These results were consistent with other studies of the effect
of environmental resource availability on foliage composition. Similar results were observed when the C:N ratio of leaves
was increased under elevated CO2. The changes in leaf chemistry induced by the treatments affected the performance of 4th-instar larvae of Chrysophtharta flaveola (Chapuis) fed on the leaves. Increased C:N ratios of leaves reduced digestive efficiencies and pupal body sizes and increased
mortality. Below a threshold nitrogen concentration of approximately 1% dry mass, severe reductions in the performance of
larvae were recorded. Such changes may have significant consequences for herbivores of Eucalyptus, particularly in view of projected increases in atmospheric CO2.
Received: 8 January 1996 / Accepted: 26 June 1996 相似文献
4.
Seeds of Gliricidia
sepium, a fast-growing woody legume native to seasonal tropical forests of Central America, were inoculated with N2-fixing Rhizobium bacteria and grown in environmentally controlled glasshouses for 67–71 days under ambient CO2 (35 Pa) and elevated CO2 (70 Pa) conditions. Seedlings were watered with an N-free, but otherwise complete, nutrient solution such that bacterial N2 fixation was the only source of N available to the plant. The primary objective of our study was to quantify the effect of
CO2 enrichment on the kinetics of photosynthate transport to nodules and determine its subsequent effect on N2 fixation. Photosynthetic rates and carbon storage in leaves were higher in elevated CO2 plants indicating that more carbon was available for transport to nodules. A 14CO2 pulse-chase experiment demonstrated that photosynthetically fixed carbon was supplied by leaves to nodules at a faster rate
when plants were grown in elevated CO2. Greater rates of carbon supply to nodules did not affect nodule mass per plant, but did increase specific nitrogenase activity
(SNA) and total nitrogenase activity (TNA) resulting in greater N2 fixation. In fact, a 23% increase in the rate of carbon supplied to nodules coincided with a 23% increase in SNA for plants
grown in elevated CO2, suggesting a direct correlation between carbon supply and nitrogenase activity. The improvement in plant N status produced
much larger plants when grown in elevated CO2. These results suggest that Gliricidia, and possibly other N2-fixing trees, may show an early and positive growth response to elevated CO2, even in severely N-deficient soils, due to increased nitrogenase activity.
Received: 27 February 1996 / Accepted: 19 June 1996 相似文献
5.
Mycorrhizas alter the acquisition of carbon and nutrients, thereby affecting numerous plant and ecosystem processes. It is
important, therefore, to determine how mycorrhizal populations will change under possible future climate conditions. Individual
and interactive effects of elevated atmospheric CO2 concentration and atmospheric temperature were assessed in a 2×2 factorial design [ambient and elevated (200 ppm above ambient)
CO2 concentrations, and ambient and elevated (4°C above ambient) temperatures]. In June 1993, 2-year-old Douglas fir (Pseudotsuga menziesii Mirb. Franco) seedlings were planted in 12 environment-tracking chambers (n=3) containing reconstructed, low-nitrogen, native forest soil. Climate treatments were imposed shortly thereafter, and the
seedlings grew until June 1997. Soil cores were taken twice per year during the exposure period. We present findings on changes
in the community structure of ectomycorrhizal (ECM) root tips, categorized into morphotypes using gross morphological traits.
A diverse and stable community of morphotypes (a total of 40) was encountered; no more than 30 of which were seen at any sampling
time. In the first sample, there were only 15 morphotypes found in the 12 chambers. Morphotype numbers increased during the
first half of the experiment, remaining fairly constant thereafter. Near the end of the exposure, elevated-temperature treatments
maintained more morphotypes than ambient treatments. However, overall, absolute measures (number of ECM tips) were affected
primarily by CO2 treatment, whereas proportional measures (e.g., Simpson’s index) were affected primarily by temperature. While some morphotypes
were negatively affected seasonally by higher temperatures (putative Rhizopogon group), others (Cenococcum) seemed to thrive. Underlying the dominant patterns of change in diversity, driven by the Rhizopogon group, subdominant populations responded slightly differently. Community diversity through time tended to increase at a greater
rate for all subdominant populations compared with the rate when dominant populations were included.
Received: 16 August 1999 / Accepted: 2 March 2000 相似文献
6.
Quantitative integration of the literature on the effect of elevated CO2 on woody plants is important to aid our understanding of forest health in coming decades and to better predict terrestrial
feedbacks on the global carbon cycle. We used meta-analytic methods to summarize and interpret more than 500 reports of effects
of elevated CO2 on woody plant biomass accumulation and partitioning, gas exchange, and leaf nitrogen and starch content. The CO2 effect size metric we used was the log-transformed ratio of elevated compared to ambient response means weighted by the inverse
of the variance of the log ratio. Variation in effect size among studies was partitioned according to the presence of interacting
stress factors, length of CO2 exposure, functional group status, pot size, and type of CO2 exposure facility. Both total biomass (W
T) and net CO2 assimilation (A) increased significantly at about twice ambient CO2, regardless of growth conditions. Low soil nutrient availability reduced the CO2 stimulation of W
T by half, from +31% under optimal conditions to +16%, while low light increased the response to +52%. We found no significant
shifts in biomass allocation under high CO2. Interacting stress factors had no effect on the magnitude of responses of A to CO2, although plants grown in growth chambers had significantly lower responses (+19%) than those grown in greenhouses or in
open-top chambers (+54%). We found no consistent evidence for photosynthetic acclimation to CO2 enrichment except in trees grown in pots <0.5 l (−36%) and no significant CO2 effect on stomatal conductance. Both leaf dark respiration and leaf nitrogen were significantly reduced under elevated CO2 (−18% and −16% respectively, data expressed on a leaf mass basis), while leaf starch content increased significantly except
in low nutrient grown gymnosperms. Our results provide robust, statistically defensible estimates of elevated CO2 effect sizes against which new results may be compared or for use in forest and climate model parameterization.
Received: 16 May 1997 / Accepted: 9 September 1997 相似文献
7.
J. D. Barnes I. Bettarini A. Polle N. Slee C. Raines F. Miglietta A. Raschi M. Fordham 《Oecologia》1997,110(2):169-178
The aim of this study was to characterise growth and photosynthetic capacity in plants adapted to long-term contrasting atmospheric
CO2 concentrations (C
a). Seeds of Agrostis canina L. ssp. monteluccii were collected from a natural CO2 transect in central-western Italy and plants grown in controlled environment chambers at both ambient and elevated CO2 (350 and 700 μmol mol−1) in nutrient-rich soil. Seasonal mean C
a at the source of the plant material ranged from 610 to 451 μmol CO2 mol−1, derived from C4 leaf stable carbon isotope discrimination (δ13C). Under chamber conditions, CO2 enrichment stimulated the growth of all populations. However, plants originating from elevated C
a exhibited higher initial relative growth rates (RGRs) irrespective of chamber CO2 concentrations and a positive relationship was found between RGR and C
a at the seed source. Seed weight was positively correlated with C
a, but differences in seed weight were found to explain no more than 34% of the variation in RGRs at elevated CO2. Longer-term experiments (over 98 days) on two populations originating from the extremes of the transect (451 and 610 μmol
CO2 mol−1) indicated that differences in growth between populations were maintained when plants were grown at both 350 and 700 μmol
CO2 mol−1. Analysis of leaf material revealed an increase in the cell wall fraction (CWF) in plants grown at elevated CO2, with plants originating from high C
a exhibiting constitutively lower levels but a variable response in terms of the degree of lignification. In vivo gas exchange measurements revealed no significant differences in light and CO2 saturated rates of photosynthesis and carboxylation efficiency between populations or with CO2 treatment. Moreover, SDS-PAGE/ LISA quantification of leaf ribulose bisphosphate carboxylase/oxygenase (Rubisco) showed no
difference in Rubisco content between populations or CO2 treatments. These findings suggest that long-term adaptation to growth at elevated CO2 may be associated with a potential for increased growth, but this does not appear to be linked with differences in the intrinsic
capacity for photosynthesis.
Received: 16 August 1996 / Accepted: 19 October 1996 相似文献
8.
Epichloe bromicola is an endophytic fungal species that systemically and perennially colonizes intercellular spaces of leaf blades, leaf sheaths and culms of Bromus grass species. E. bromicola causes choke disease in B. erectus, suppressing maturation of most, if not all, host inflorescences. In an investigation of the interaction between fungus and host, we used a quantitative polymerase chain reaction technique to estimate the amount of fungal DNA, and thereby fungal concentration, in host plants. Fungal concentration was directly correlated with vegetative vigour of the plant, as measured by longest leaf length, number of tillers and vegetative above-ground biomass, suggesting that, during vegetative growth, the endophytic fungus is most beneficial for the plant when present in high concentrations. In contrast, the reproduction of the plant, as measured by the number of functional inflorescences, was inversely correlated with fungal concentration: the majority of infected plants, and all that were associated with high concentrations of fungi, were diseased. Thus, the benefit of endophyte infection for the plant is coupled with the disadvantages of infertility. Fungal concentration was shown to be at least in part genetically determined because fungal concentration differed significantly in different plant-endophyte genotype combinations (symbiotum). In a field experiment with normal and CO2-enriched environments, elevated CO2 levels favoured fungal reproductive vigour over host reproductive vigour, suggesting that these plant endophytes would be at a selective advantage in a corresponding environmental-change scenario. We conclude that a dynamic and complex relationship between fungal endophyte infection, fungal concentration, genotype and environment affects growth and fecundity of B. erectus and should contribute to the evolution of these plant-fungal interactions. 相似文献
9.
W. A. Hoffmann F. A. Bazzaz N. J. Chatterton P. A. Harrison R. B. Jackson 《Oecologia》2000,123(3):312-317
The savannas (cerrado) of south-central Brazil are currently subjected to frequent anthropogenic burning, causing widespread
reduction in tree density. Increasing concentrations of atmospheric CO2 could reduce the impact of such frequent burning by increasing the availability of nonstructural carbohydrate, which is necessary
for resprouting. We tested the hypotheses that elevated CO2 stimulates resprouting and accelerates replenishment of carbohydrate reserves. Using a factorial experiment, seedlings of
a common Brazilian savanna tree, Keilmeyera coriacea, were grown at 350 ppm and 700 ppm CO2 and at two nutrient levels. To simulate burning, the plants were either clipped at 15 weeks or were left unclipped. Among
unclipped plants, CO2 and nutrients both stimulated growth, with no significant interaction between nutrient and CO2 effects. Among clipped plants, both CO2 and nutrients stimulated resprouting. However, there was a strong interaction between CO2 and nutrient effects, with CO2 having a significant effect only in the presence of high nutrient availability. Under elevated CO2, carbohydrate reserves remained at higher levels following clipping. Root total nonstructural carbohydrate remained above
36% in all treatments, so carbohydrate reserves did not limit regrowth. These results indicate that under elevated CO2 this species may be better able to endure the high frequency of anthropogenic burning in the Brazilian savannas.
Received: 19 May 1999 / Accepted: 8 November 1999 相似文献
10.
11.
A. R. Davis 《Plant Systematics and Evolution》2003,238(1-4):169-181
Investigations of the effects of two global events – elevated CO2 levels and enhanced ultraviolet-B (UV-B) radiation – on floral nectar production are reviewed from twelve dicotyledonous
families. Furthermore, to allow comparisons between nectary morphology and nectar production in treated plants of these fifteen
species, new data on floral nectary structure are provided for Malcolmia maritima (L.) R. Br. (Brassicaceae) and Scabiosa columbaria L. (Dipsacaceae). All but the last taxon possessed mesenchymatic floral nectaries with surface stomata. Few clear relationships
existed between nectary morphology and various physiological responses to CO2 or UV-B enrichment, indicating that species responded notwithstanding nectary structure itself. Overall, nectar-solute concentration
was least affected by elevated CO2 or UV-B radiation; consequently, changes in nectar volume were responsible for differences in nectar-sugar production per
flower. Three species of Fabaceae experienced no change in floral nectar production upon exposure to elevated CO2. To date, no study of enhanced UV-B radiation reported a consistent reduction in floral nectar production; three species
of Brassicaceae responded differently, but various levels of ozone depletion were simulated. Experimentation with more taxa
– including those possessing nectary types such as septal (gynopleural) nectaries (e.g. many monocotyledons) or aggregations
of glandular trichomes – and expanding such physiological studies to species possessing extrafloral nectaries, are recommended.
Received August 8, 2002; accepted November 23, 2002
Published online: June 2, 2003 相似文献
12.
Effects of long-term CO2 enrichment and nutrient availability in Norway spruce. II. Foliar chemistry
Branches on 30-year-old Norway spruce trees [Picea abies (L.) Karst.] were exposed to ambient (AMB) or ambient plus 350 μmol CO2 mol–1 (EL) for 4 years (except winters), using the branch bag technique (BB). The trees were growing on plots with low (control)
and high (irrigated-fertilised) availability of soil nutrients. The seasonal variation in foliar macronutrients and non-structural
carbohydrates in current and 1-year-old shoots was monitored throughout the treatment period. When the branches were harvested
at the end of treatment, macronutrients were analysed in five age classes of foliage. The concentration of all elements, except
magnesium, generally increased in AMB, i.e. a ’bag effect’, but decreased as an effect of EL, i.e. a ’CO2 effect’. At the final harvest K, P, N and S were reduced in young needles by EL, whereas Mg was reduced in older needles
on both plots. A change in needle morphology by EL possibly caused a dilution effect in irrigated-fertilised needles, but
not in control needles. Reductions in K and Mg are suggested to be an effect of increased phloem transport from the branch,
in consequence of higher rates of carbon fixation in EL. Foliage in BBs had higher concentration of Ca, but there was no significant
effect of the EL-treatment, indicating that elevated CO2 had no effect on stomatal conductance. Quinic acid concentration decreased, but shikimic acid concentration increased in
BBs, independently of CO2 treatment. Concentrations of starch and sugars increased in the EL-treatment, but pinitol decreased.
Received: 23 October 1998 / Accepted: 1 December 1998 相似文献
13.
Several previous studies have observed that species and individuals with large seeds respond more positively to elevated CO (2) than those with small seeds. We explored the reasons for this pattern by examining the relationship between seed size and CO (2) response in Picea abies and P. rubens using growth analysis. The large seeded species (P. abies) responded more positively to elevated CO (2) than the small seeded species (P. rubens). At the intraspecific level, P. abies individuals from large seeds responded more positively to elevated CO (2) than individuals from small seeds, however, there was no significant intraspecific variation in CO (2) response in P. rubens. The greater CO (2) response of plants from large seeds was not simply the result of a larger starting capital compounded at the same rate as in plants from small seeds. Elevated CO (2) increased relative growth rate to a greater extent in individuals from large seeds. This effect appears to be related to differences in time of establishment, source to sink ratio and nutrient availability with seed size. These results are significant not only in understanding the potential effect of rising atmospheric CO (2) concentrations on plant populations, but also in understanding the factors affecting plant success at current atmospheric CO (2) levels due to the elevation of CO (2) within the litter layer that occurs at many germination sites. 相似文献
14.
沙埋对无芒雀麦种子萌发和幼苗生长的影响 总被引:4,自引:0,他引:4
研究了沙埋对浑善达克沙地植物群落中多年生禾草无芒雀麦种子萌发、出苗和幼苗生长的影响.结果表明:无芒雀麦种子能在深度≤12cm的沙埋中萌发,≤8cm的沙埋中出苗.在此范围内,随着沙埋深度的增加,无芒雀麦种子的萌发率和出苗率逐渐降低.沙埋深度在植株高度的33%时,无芒雀麦1周龄和2周龄幼苗均全部存活,且总生物量≥对照(未沙埋幼苗);当沙埋深度增至植株高度的66%时,1周龄和2周龄幼苗的存活率分别降至70%和25%,生长也受到抑制;而遭受全部沙埋时,1周龄和2周龄幼苗均不能存活.遭受沙埋后,无芒雀麦幼苗分配较多的生物量用于地上部分的生长,其生物量分配模式改变可能是无芒雀麦幼苗对沙埋环境的重要适应对策. 相似文献
15.
M. E. Kubiske Kurt S. Pregitzer Carl J. Mikan Donald R. Zak Jennifer L. Maziasz A. Teeri 《Oecologia》1997,110(3):328-336
We tested the hypothesis that elevated CO2 would stimulate proportionally higher photosynthesis in the lower crown of Populus trees due to less N retranslocation, compared to tree crowns in ambient CO2. Such a response could increase belowground C allocation, particularly in trees with an indeterminate growth pattern such
as Populus tremuloides. Rooted cuttings of P. tremuloides were grown in ambient and twice ambient (elevated) CO2 and in low and high soil N availability (89 ± 7 and 333 ± 16 ng N g−1 day−1 net mineralization, respectively) for 95 days using open-top chambers and open-bottom root boxes. Elevated CO2 resulted in significantly higher maximum leaf photosynthesis (A
max) at both soil N levels. A
max was higher at high N than at low N soil in elevated, but not ambient CO2. Photosynthetic N use efficiency was higher at elevated than ambient CO2 in both soil types. Elevated CO2 resulted in proportionally higher whole leaf A in the lower three-quarters to one-half of the crown for both soil types. At elevated CO2 and high N availability, lower crown leaves had significantly lower ratios of carboxylation capacity to electron transport
capacity (V
cmax/J
max) than at ambient CO2 and/or low N availability. From the top to the bottom of the tree crowns, V
cmax/J
max increased in ambient CO2, but it decreased in elevated CO2 indicating a greater relative investment of N into light harvesting for the lower crown. Only the mid-crown leaves at both
N levels exhibited photosynthetic down regulation to elevated CO2. Stem biomass segments (consisting of three nodes and internodes) were compared to the total A
leaf for each segment. This analysis indicated that increased A
leaf at elevated CO2 did not result in a proportional increase in local stem segment mass, suggesting that C allocation to sinks other than the
local stem segment increased disproportionally. Since C allocated to roots in young Populus trees is primarily assimilated by leaves in the lower crown, the results of this study suggest a mechanism by which C allocation
to roots in young trees may increase in elevated CO2.
Received: 12 August 1996 / Accepted: 12 November 1996 相似文献
16.
17.
Shili Miao 《植被学杂志》1995,6(5):697-700
Abstract. In order to explore whether seed size affects plant response to elevated CO2, plants grown from red oak (Quercus rubra L.) acorns were studied for differences in their first year response to CO2 concentrations of 350 and 700 μl/l. Overall, at final harvest, total biomass of plants grown in elevated CO2 were 47 % larger than that of plants grown in ambient CO2. There were significant interactions between CO2 treatments and initial acorn mass for total biomass, as well as for root, leaf, and stem biomass. Although total biomass increased with increasing initial acorn mass for both high and ambient CO2 plants, high CO2 plants exhibited a greater increase than ambient CO2 plants, as indicated by a steeper slope in high CO2 plants. However, CO2 levels did not affect biomass partitioning traits, such as root/shoot ratio, leaf, stem, and root weight ratios, and leaf area ratio. These results suggest that variation in seed size or initial plant size can cause intraspecific variation in response to elevated CO2. 相似文献
18.
CO2浓度升高对棉铃虫生长发育和繁殖的直接影响 总被引:2,自引:0,他引:2
利用CDCC-1型密闭式动态CO2气室,在人工饲料下研究了不同CO2浓度(750μl/L vs.370μl/L)对棉铃虫生长发育和繁殖的直接影响,以及对棉铃虫幼虫体内营养物质和酶的含量。结果表明:(1)高CO2浓度大气中生长的棉铃虫种群发育延缓,单雌产卵量增加,虫体重量减轻,内禀增长率下降,而对人工饲料的消耗量和粪便排泄量增加。与对照相比,高CO2浓度下饲养的棉铃虫幼虫的发育历期延缓了15.14%(P〈0.01),幼虫的取食量增加了8.03%(P〈0.01),粪便量增加了14.54%(P〈0.05)。(2)高CO2浓度可影响棉铃虫幼虫对人工饲料的利用效率。与对照相比,在750μl/L CO2饲养下棉铃虫幼虫的相对消耗率、生长效率,食物转化率和近似消化率均有所降低。(3)高CO2浓度还改变了棉铃虫幼虫体内的营养物质的含量和酶的活性。与对照比较,750μl/L CO2饲养下棉铃虫幼虫体内蛋白质和总氨基酸含量分别下降了14.16%(P〈0.01)和28.40%(P〈0.01);超氧化物歧化酶、乙酰胆碱酯酶和淀粉酶的活性分别增加了26.43%、9.12%和40.17%,而谷胱甘肽过氧化物酶的活性则下降了20.25%(P〈0.01)。 相似文献
19.
为明确大气CO2浓度升高对草地贪夜蛾Spodoptera frugiperda及其本地近缘种斜纹夜蛾Spodoptera litura生长发育和繁殖的影响。本研究在正常二氧化碳浓度(400 μL/L)和倍增二氧化碳浓度(800 μL/L)下,用寄主植物小麦饲养草地贪夜蛾和斜纹夜蛾,研究CO2浓度升高对草地贪夜蛾及斜纹夜蛾发育历期和繁殖力的直接影响(高CO2浓度直接影响试虫)、间接影响(高CO2浓度通过影响小麦间接影响试虫)及综合影响(小麦和试虫同时受高CO2浓度影响)。结果表明,CO2浓度升高对草地贪夜蛾各虫态的发育历期均有较显著影响,完成整个世代的时间显著缩短,其中间接影响组幼虫期较对照组显著延长0.7 d,而蛹期和成虫期寿命分别显著缩短1.5 d和4.9 d;综合影响组幼虫期较对照组显著延长0.8 d,而蛹期和成虫期寿命分别显著缩短1.2 d和5.7 d;直接影响组草地贪夜蛾蛹期显著缩短2.7 d;CO2浓度升高对斜纹夜蛾各虫态发育历期影响不显著,仅直接影响组的各虫态发育历期缩短较为明显。在CO2浓度升高条件下,草地贪夜蛾直接影响组单雌产卵量显著增加1 220.48粒,综合影响组略有减少;而斜纹夜蛾单雌产卵量在高CO2浓度下均呈现下降趋势,其中综合影响显著减少818.20粒。说明CO2浓度升高加快了草地贪夜蛾的种群增长速率,使其完成整个世代的时间显著降低;但对本地近缘种斜纹夜蛾的影响不显著。因此,在未来CO2浓度升高的情况下,入侵种草地贪夜蛾的种群增长速率将大于其本地近缘种斜纹夜蛾。 相似文献
20.
Two branches of a field-grown Chamaecy-paris obtusa tree were enclosed in chambers of an open gas exchange system for continuous CO2 exchange measurements. One branch was subjected to ambient air (CO2, 370 μmol mol–1) and the other was subjected to CO2-enriched air (800 μmol mol–1). The CO2 exchange rate of the branches, air temperature and photosynthetic photon flux density were recorded every 4 min by a computer
during the two experimental periods of July 1994 to June 1995 (experiment 1) and April 1996 to August 1997 (experiment 2).
The response of CO2 gas exchange rate to light changed with the seasonal temperature. The highest saturated rate of net photosynthesis on a leaf
area basis was observed in May and October in both CO2 treatments when the mean daytime temperature was about 18–19°C. This temperature was almost equal to the yearly mean daytime
temperature. Above and below this temperature, the saturated net photosynthesis rate decreased. The net photosynthesis rate
was usually higher in the elevated CO2 treatment. The ratio of monthly net photosynthesis rate in elevated CO2 to that in ambient CO2 was linearly related to the monthly mean daytime temperature. This ratio increased by 3.3% for each 1°C increase in the monthly
mean daytime temperature; the highest ratio of 1.8 occurred in August. When the ratio was 1.0, the temperature was about 5–6°C,
which was close to the mean daytime temperature of the coldest month. Elevated CO2 increased per unit area net photosynthesis by 38.5% and 43.7% in experiments 1 and 2, respectively.
Received: 29 March 1999 / Accepted: 22 October 1999 相似文献