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1.
Multichannel automated chamber system for continuous monitoring of CO2 exchange between the agro-ecosystem or soil and the atmosphere 总被引:1,自引:0,他引:1
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A multichannel automated chamber system was developed for continuous monitoring of CO2 exchange at multiple points between agro-ecosystem or soil and atmosphere. This system consisted of an automated chamber subsystem with a CO2 concentration analyzer and a data logging subsystem. Both subsystems were under the control of a programmable logic controller (PLC). The automated chamber subsystem contained 18 chambers (50 cm × 50 cm × 50 cm) and a compressor. The chamber lids were closed and can be automatically opened. During measurement, one of the 18 chambers was kept closed for three minutes for measuring and the other chambers were kept open to maintain the natural soil conditions to the maximum extent. Environmental variables were simultaneously measured using sensors and recorded by the data logger. The reliability of the multichannel automated chamber system was tested and the results showed that the turbulence of the fans had no significant effect on the CO2 exchange. The changes in the air and the temperature of soil and soil moisture inside the chambers, caused by the enclosure of the chambers, were not significant. The net ecosystem CO2 exchange for the wheat ecosystem was ?2.35 μmol·m?2·s>?1 and the soil respiration was 3.87 μmol·m?2·s>?1 in the wheat field, and 6.61 μmol·m?2·s>?1 in the apple orchard. 相似文献
2.
用于测定陆地生态系统与大气间CO2交换通量的多通道全自动通量箱系统 总被引:5,自引:0,他引:5
陆地生态系统与大气间CO2交换是全球碳循环的最重要组成部分,科学地测定其CO2交换通量一直是陆地生态系统碳循环研究的核心工作之一。提高观测的效率和减少观测对自然的干扰,是科学精确地估算区域和全球尺度上的陆地生态系统与大气间CO2交换量的关键。在参考国内外已有的陆地生态系统与大气间CO2交换通量箱式法观测技术的基础上,发展了一套多通道全自动通量箱系统用来连续观测陆地生态系统或土壤与大气间的CO2交换通量。在黄土高原中国科学院长武农业生态试验站的麦田和苹果园中进行了系统测试,结果表明,该系统不但能够实现自动、连续、多点观测,而且对自然环境的影响比较小,在田间的实验观测中,该系统运行稳定,能够比较客观地得到陆地生态系统与大气间的CO2交换通量。 相似文献
3.
N. S. Balaur V. A. Vorontsov E. I. Kleiman Yu. D. Ton 《Russian Journal of Plant Physiology》2009,56(3):423-427
A novel technique designed for component monitoring of CO2 exchange in plants is described. The system is based on application of self-clamping leaf chambers connected to an open gas-exchange measuring system and on automatic recording of CO2 concentration. This technique was implemented in a commercially available instrument, PTM-48A Photosynthesis Monitor, which provides for long-term measurements of gas exchange and for discrimination of its separate components. Furthermore, many other plant functions can be monitored during plant growth and development under laboratory, greenhouse, and field conditions. 相似文献
4.
Zhili He Jinbo Xiong Angela D Kent Ye Deng Kai Xue Gejiao Wang Liyou Wu Joy D Van Nostrand Jizhong Zhou 《The ISME journal》2014,8(3):714-726
The concentrations of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) have been rising due to human activities. However, little is known about how such increases influence soil microbial communities. We hypothesized that elevated CO2 (eCO2) and elevated O3 (eO3) would significantly affect the functional composition, structure and metabolic potential of soil microbial communities, and that various functional groups would respond to such atmospheric changes differentially. To test these hypotheses, we analyzed 96 soil samples from a soybean free-air CO2 enrichment (SoyFACE) experimental site using a comprehensive functional gene microarray (GeoChip 3.0). The results showed the overall functional composition and structure of soil microbial communities shifted under eCO2, eO3 or eCO2+eO3. Key functional genes involved in carbon fixation and degradation, nitrogen fixation, denitrification and methane metabolism were stimulated under eCO2, whereas those involved in N fixation, denitrification and N mineralization were suppressed under eO3, resulting in the fact that the abundance of some eO3-supressed genes was promoted to ambient, or eCO2-induced levels by the interaction of eCO2+eO3. Such effects appeared distinct for each treatment and significantly correlated with soil properties and soybean yield. Overall, our analysis suggests possible mechanisms of microbial responses to global atmospheric change factors through the stimulation of C and N cycling by eCO2, the inhibition of N functional processes by eO3 and the interaction by eCO2 and eO3. This study provides new insights into our understanding of microbial functional processes in response to global atmospheric change in soybean agro-ecosystems. 相似文献
5.
Open top chambers for exposing plant canopies to elevated CO2 concentration and for measuring net gas exchange 总被引:1,自引:0,他引:1
Open top chamber design and function are reviewed. All of the chambers described maintain CO2 concentrations measured at a central location within ±30 ppm of a desired target when averaged over the growing season, but the spatial and temporal range within any chamber may be closer to 100 ppm. Compared with unchambered companion plots, open top chambers modify the microenvironment in the following ways: temperatures are increased up to 3°C depending on the chamber design and location of the measurement; light intensity is typically diminished by as much as 20%; wind velocity is lower and constant; and relative humidity is higher. The chamber environment may significantly alter plant growth when compared with unchambered controls, but the chamber effect on growth has not been clearly attributed to a single or even a few environmental factors.A method for modifying an open top chamber for tracking gas exchange between natural vegetation and the ambient air is described. This modification consists of the addition of a top with exit chimney to reduce dilution of chamber CO2 by external ambient air, is quickly made and permits estimation of the effects of elevated CO2 and water vapor exchange.The relatively simple design and construction of open top chambers make them the most likely method to be used in the near future for long-term elevated CO2 exposure of small trees, crops and grassland ecosystems. Improvements in the basic geometry to improve control of temperature, reduce the variation of CO2 concentrations, and increase the turbulence and wind speed in the canopy boundary layer are desirable objectives. Similarly, modifications for measuring water vapor and carbon dioxide gas exchange will extend the usefulness of open top chambers to include non-destructive monitoring of the responses of ecosystems to rising atmospheric CO2. 相似文献
6.
Daily and seasonal CO2 exchange in Scots pine grown under elevated O3 and CO2: experiment and simulation 总被引:3,自引:0,他引:3
Starting in early spring of 1994, naturally regenerated, 30-year-old Scots pine (Pinus sylvestris L.) trees were grown in open-top chambers and exposed in situ to doubled ambient O3,doubled ambient CO2 and a combination of O3 and CO2 from 15 April to 15 September. To investigate daily and seasonal responses of CO2 exchange to elevated O3 and CO2, the CO2 exchange of shoots was measured continuously by an automatic system for measuring gas exchange during the course of one year (from 1 Januray to 31 December 1996). A process-based model of shoot photosynthesis was constructed to quantify modifications in the intrinsic capacity of photosynthesis and stomatal conductance by simulating the daily CO2 exchange data from the field. Results showed that on most days of the year the model simulated well the daily course of shoot photosynthesis. Elevated O3 significantly decreased photosynthetic capacity and stomatal conductance during the whole photosynthetic period. Elevated O3 also led to a delay in onset of photosynthetic recovery in early spring and an increase in the sensitivity of photosynthesis to environmental stress conditions. The combination of elevated O3 and CO2 had an effect on photosynthesis and stomatal conductance similar to that of elevated O3 alone, but significantly reduced the O3-induced depression of photosynthesis. Elevated CO2 significantly increased the photosynthetic capacity of Scots pine during the main growing season but slightly decreased it in early spring and late autumn. The model calculation showed that, compared to the control treatment, elevated O3 alone and the combination of elevated O3 and CO2 decreased the annual total of net photosynthesis per unit leaf area by 55% and 38%, respectively. Elevated CO2 increased the annual total of net photosynthesis by 13%. 相似文献
7.
George T. Byrd T. Loboda Clanton C. Black Jr. R. Harold Brown 《Photosynthesis research》1995,44(3):253-260
Onion (Allium cepa L.) plants were examined to determine the photosynthetic role of CO2 that accumulates within their leaf cavities. Leaf cavity CO2 concentrations ranged from 2250 L L–1 near the leaf base to below atmospheric (<350 L L–1) near the leaf tip at midday. There was a daily fluctuation in the leaf cavity CO2 concentrations with minimum values near midday and maximum values at night. Conductance to CO2 from the leaf cavity ranged from 24 to 202 mol m–2 s–1 and was even lower for membranes of bulb scales. The capacity for onion leaves to recycle leaf cavity CO2 was poor, only 0.2 to 2.2% of leaf photosynthesis based either on measured CO2 concentrations and conductance values or as measured directly by 14CO2 labeling experiments. The photosynthetic responses to CO2 and O2 were measured to determine whether onion leaves exhibited a typical C3-type response. A linear increase in CO2 uptake was observed in intact leaves up to 315 L L–1 of external CO2 and, at this external CO2 concentration, uptake was inhibited 35.4±0.9% by 210 mL L–1 O2 compared to 20 mL L–1 O2. Scanning electron micrographs of the leaf cavity wall revealed degenerated tissue covered by a membrane. Onion leaf cavity membranes apparently are highly impermeable to CO2 and greatly restrict the refixation of leaf cavity CO2 by photosynthetic tissue.Abbreviations Ca
external CO2 concentration
- Ci
intercellular CO2 concentration
-
CO2 compensation concentration
- PPFR
photosynthetic photon fluence rate 相似文献
8.
Pseudo-cubic spline functions were applied to the two atmospheric CO2 concentrations of 340 and 600 l·l–1 CO2 for describing the average daily CO2 gas exchange rates of simplifed grassland model ecosystems. Measurements used were from daily means of photon flux density (PhAR), temperature and relative air humidity, phytomass of each day, leaf area indexes, average phenological states of the vegetation (1–15), and water exchange rates of the entire model ecosystems. The functions were validated with, data from the same experimental year. We also succeeded in verifying the functions with the response data from years other than those used for constructing the model. 相似文献
9.
L. F. Liebes V. M. Maher P. Scherr J. J. McCormick 《In vitro cellular & developmental biology. Plant》1976,12(3):265-268
Summary The use and construction of an automatic gas tank switching system are described. This device monitors the gas pressure in
a CO2 incubator gas system and automatically switches to a reserve tank when the main supply tank is depleted. The unit contains
an alarm system that signals either a loss of power or of gas pressure in the supply system.
This research was supported by National Cancer Institute Contract No 1-CP-33226, grants CA 13058 and CA 14680 and an institutional
grant to the Michigan Cancer Foundation by the United Foundation of Greater Detroit. 相似文献
10.
Acclimation of photosynthesis to increasing atmospheric CO2: The gas exchange perspective 总被引:9,自引:0,他引:9
Rowan F. Sage 《Photosynthesis research》1994,39(3):351-368
The nature of photosynthetic acclimation to elevated CO2 is evaluated from the results of over 40 studies focusing on the effect of long-term CO2 enrichment on the short-term response of photosynthesis to intercellular CO2 (the A/Ci response). The effect of CO2 enrichment on the A/Ci response was dependent on growth conditions, with plants grown in small pots (< 5 L) or low nutrients usually exhibiting a reduction of A at a given Ci, while plants grown without nutrient deficiency in large pots or in the field tended to exhibit either little reduction or an enhancement of A at a given Ci following a doubling or tripling of atmospheric CO2 during growth. Using theoretical interpretations of A/Ci curves to assess acclimation, it was found that when pot size or nutrient deficiency was not a factor, changes in the shape of A/Ci curves which are indicative of a reallocation of resources within the photosynthetic apparatus typically were not observed. Long-term CO2 enrichment usually had little effect or increased the value of A at all Ci. However, a minority of species grown at elevated CO2 exhibited gas exchange responses indicative of a reduced amount of Rubisco and an enhanced capacity to metabolize photosynthetic products. This type of response was considered beneficial because it enhanced both photosynthetic capacity at high CO2 and reduced resource investment in excessive Rubisco capacity. The ratio of intercellular to ambient CO2 (the Ci/Ca ratio) was used to evaluate stomatal acclimation. Except under water and humidity stress, Ci/Ca exhibited no consistent change in a variety of C3 species, indicating no stomatal acclimation. Under drought or humidity stress, Ci/Ca declined in high-CO2 grown plants, indicating stomata will become more conservative during stress episodes in future high CO2 environments.Abbreviations A
net CO2 assimilation rate
- Ci (Ca)
intercellular (ambient) partial pressure of CO2
- operational Ci
intercellular partial pressure of CO2 at a given ambient partial pressure of CO2
- gs
stomatal conductance
- normal CO2
current atmospheric mole fraction of CO2 (330 to 355 mol mol–1)
- Rubisco
ribulose-1,5-bisphosphate carboxylase/oxygenase 相似文献
11.
The role of land plants in establishing our present day atmosphere is analysed. Before the evolution of land plants, photosynthesis by marine and fresh water organisms was not intensive enough to deplete CO2 from the atmosphere, the concentration of which was more than the order of magnitude higher than present. With the appearance of land plants, the exudation of organic acids by roots, following respiratory and photorespiratory metabolism, led to phosphate weathering from rocks thus increasing aquatic productivity. Weathering also replaced silicates by carbonates, thus decreasing the atmospheric CO2 concentration. As a result of both intensive photosynthesis and weathering, CO2 was depleted from the atmosphere down to low values approaching the compensation point of land plants. During the same time period, the atmospheric O2 concentration increased to maximum levels about 300 million years ago (Permo-Carboniferous boundary), establishing an O2/CO2 ratio above 1000. At this point, land plant productivity and weathering strongly decreased, exerting negative feedback on aquatic productivity. Increased CO2 concentrations were triggered by asteroid impacts and volcanic activity and in the Mesozoic era could be related to the gymnosperm flora with lower metabolic and weathering rates. A high O2/CO2 ratio is metabolically linked to the formation of citrate and oxalate, the main factors causing weathering, and to the production of reactive oxygen species, which triggered mutations and stimulated the evolution of land plants. The development of angiosperms resulted in a decrease in CO2 concentration during the Cenozoic era, which finally led to the glacial-interglacial oscillations in the Pleistocene epoch. Photorespiration, the rate of which is directly related to the O2/CO2 ratio, due to the dual function of Rubisco, may be an important mechanism in maintaining the limits of O2 and CO2 concentrations by restricting land plant productivity and weathering. 相似文献
12.
Taiji Kou Jianguo Zhu Zubin Xie Toshihiro Hasegawa Katia Heiduk 《Plant and Soil》2007,299(1-2):237-249
Soil respiration in a cropland is the sum of heterotrophic (mainly microorganisms) and autotrophic (root) respiration. The
contribution of both these types to soil respiration needs to be understood to evaluate the effects of environmental change
on soil carbon cycling and sequestration. In this paper, the effects of free-air CO2 enrichment (FACE) on hetero- and autotrophic respiration in a wheat field were differentiated and evaluated by a novel split-root
growth and gas collection system. Elevated atmospheric pCO2 of approximately 200 μmol mol−1 above the ambient pCO2 significantly increased soil respiration by 15.1 and 14.8% at high nitrogen (HN) and low nitrogen (LN) application rates,
respectively. The effect of elevated atmospheric pCO2 on root respiration was not consistent across the wheat growth stages. Elevated pCO2 significantly increased and decreased root respiration at the booting-heading stage (middle stage) and the late-filling stage
(late stage), respectively, in HN and LN treatments; however, no significant effect was found at the jointing stage (early
stage). Thus, the effect of increased pCO2 on cumulative root respiration for the entire wheat growing season was not significant. Cumulative root respiration accounted
for approximately 25–30% of cumulative soil respiration in the entire wheat growing season. Consequently, cumulative microbial
respiration (soil respiration minus root respiration) increased by 22.5 and 21.1% due to elevated pCO2 in HN and LN, respectively. High nitrogen application significantly increased root respiration at the late stage under both
elevated pCO2 and ambient pCO2; however, no significant effects were found on cumulative soil respiration, root respiration, and microbial respiration.
These findings suggest that heterotrophic respiration, which is influenced by increased substrate supplies from the plant
to the soil, is the key process to determine C emission from agro-ecosystems with regard to future scenarios of enriched pCO2. 相似文献
13.
Non-phototrophic CO
2
fixation by soil microorganisms 总被引:1,自引:0,他引:1
Anja Miltner Frank-Dieter Kopinke Reimo Kindler Draženka Selesi Anton Hartmann Matthias Kästner 《Plant and Soil》2005,269(1-2):193-203
Although soils are generally known to be a net source of CO2 due to microbial respiration, CO2 fixation may also be an important process. The non-phototrophic fixation of CO2 was investigated in a tracer experiment with 14CO2 in order to obtain information about the extent and the mechanisms of this process. Soils were incubated for up to 91 days
in the dark. In three independent incubation experiments, a significant transfer of radioactivity from 14CO2 to soil organic matter was observed. The process was related to microbial activity and could be enhanced by the addition
of readily available substrates such as acetate. CO2 fixation exhibited biphasic kinetics and was linearly related to respiration during the first phase of incubation (about
20–40 days). The fixation amounted to 3–5% of the net respiration. After this phase, the CO2 fixation decreased to 1–2% of the respiration. The amount of carbon fixed by an agricultural soil corresponded to 0.05% of
the organic carbon present in the soil at the beginning of the experiment, and virtually all of the fixed CO2 was converted to organic compounds. Many autotrophic and heterotrophic biochemical processes result in the fixation of CO2. However, the enhancement of the fixation by addition of readily available substrates and the linear correlation with respiration
suggested that the process is mainly driven by aerobic heterotrophic microorganisms. We conclude that heterotrophic CO2 fixation represents a significant factor of microbial activity in soils. 相似文献
14.
15.
Soil N availability may play an important role in regulating the long-term responses of plants to rising atmospheric CO2 partial pressure. To further examine the linkage between above- and belowground C and N cycles at elevated CO2, we grew clonally propagated cuttings of Populus grandidentata in the field at ambient and twice ambient CO2 in open bottom root boxes filled with organic matter poor native soil. Nitrogen was added to all root boxes at a rate equivalent
to net N mineralization in local dry oak forests. Nitrogen added during August was enriched with 15N to trace the flux of N within the plant-soil system. Above-and belowground growth, CO2 assimilation, and leaf N content were measured non-destructively over 142 d. After final destructive harvest, roots, stems,
and leaves were analyzed for total N and 15N.
There was no CO2 treatment effect on leaf area, root length, or net assimilation prior to the completion of N addition. Following the N addition,
leaf N content increased in both CO2 treatments, but net assimilation showed a sustained increase only in elevated CO2 grown plants. Root relative extension rate was greater at elevated CO2, both before and after the N addition. Although final root biomass was greater at elevated CO2, there was no CO2 effect on plant N uptake or allocation. While low soil N availability severely inhibited CO2 responses, high CO2 grown plants were more responsive to N. This differential behavior must be considered in light of the temporal and spatial
heterogeneity of soil resources, particularly N which often limits plant growth in temperate forests. 相似文献
16.
Leaf conductance gL is strongly influenced by environmental factors like CO2, irradiance and air humidity. According to Ball et al. (1987), gL is correlated with an index calculated as the product of net CO2 exchange rate A and ambient water vapour concentration Wa, divided by ambient CO2 concentration ca. However, this empirical model does not apply to high values of gL observed at ca below CO2 compensation concentration . Therefore, we applied modified indices in which A is replaced by estimates for the rate of carboxylation. Such estimates, P1 and P2, were determined by adding to A the quotient of and the sum of gas phase resistance rg and intracellular resistance for CO2 exchange ri, P1 = A+/(rg + ri), or the quotient of and ri, P2 = A + /ri. If P2 is chosen, ca in the Ball index has to be replaced by the intercellular CO2 concentration ci. By using the modified indices P1·Wa/ca and P2·Wa/ci, we analysed data from the C3 species Nicotiana tabacum and Nicotiana plumbaginifolia, the C3–C4 intermediate species Diplotaxis tenuifolia, and the C4 species Zea mays. The data were collected at widely varying levels of irradiance and CO2 concentration. For all species uniform relationships between gL and the new indices were found for the whole range of CO2 concentrations below and above . Correlations between gL and P1·Wa/ca were closer than those between gL and P2·Wa/ci because P1/ca implicitly contains gL. Highly significant correlations were also obtained for the relationships between gL and the ratios P1/ca and P2/ci. 相似文献
17.
No significant differences were found between four mathematical equations describing the response of CO2 exchange rate to photosynthetic photon flux density in seven poplar clones under laboratory conditions. Choice of an optimal equation for poplar may be based on the contemplated aims. High significant differences (at p<0.001) were found among the clones.Research was supported by the Instituut tot Aanmoediging van het Wetenschappelijk Onderzoek in Nijverheid en Landbouw (I.W.O.N.L.), Brussels. 相似文献
18.
CO2 exchange, transpiration and stomatal conductance of 39 subtropical tree species were studied under five light intensities at around atmospheric air temperatures found in subtropics during the active growth period of these species. Photosynthesis rates under different light intensities were strongly dependent on leaf to air temperature differences (T). Based on T, 39 species fell in two distinct categories namely, undertemperature and overtemperature. Majority of the species in the former group were found to have relatively higher rate of photosynthesis, stomatal conductance, transpiration as well as water use efficiency. These species also showed higher light saturation for photosynthesis. The significance of the results is discussed in terms of adaptive potential in the two types of species. 相似文献
19.
Net CO2 exchange was monitored through a dark-light-dark transition, under 2% and 21% O2 in the presence and absence of CO2, in Chlamydomonas reinhardtii wild type and the high-CO2-requiring mutant ca-1-12-1C. Upon illumination at 350 l/l CO2, ca-1-12-1C cell exhibited a large decrease in net CO2 uptake following an initial surge of CO2 uptake. Net CO2 uptake subsequently attained a steady-state rate substantially lower than the maximum. A large, O2-enchanced post-illumination burst of CO2 efflux was observed after a 10-min illumination period, corresponding to a minimum in the net CO2 uptake rate. A smaller, but O2-insensitive post-illumination burst was observed following a 30-min illumination period, when net CO2 uptake was at a steady-state rate. These post-illumination bursts appeared to reflect the release of an intracellular pool of inorganic carbon, which was much larger following the initial surge of net CO2 uptake than during the subsequent steady-state CO2 uptake period.With the mutant in CO2-free gas, O2-stimulated, net CO2 efflux was observed in the light, and a small, O2-dependent post-illumination burst was observed. With wild-type cells no CO2 efflux was observed in the light in CO2-free gas under either 2% or 21% O2, but a small, O2-dependent post-illumination burst was observed. These results were interpreted as indicating that photorespiratory rates were similar in the mutant and wild-type cells in the absence of CO2, but that the wild-type cells were better able to scavenge the photorespiratory CO2. 相似文献
20.
Thermodynamics of contact angle phenomena is strongly affected by the presence of thin liquid films. However, at present, studies for CO2/brine/mineral systems only consider the films apart from contact angles. In this paper, molecular dynamics (MD) simulations have been performed to simultaneously investigate the interrelationship between water film thicknesses and water contact angles. Two types of contact angles were considered namely Young’s contact angle (no water film is present) and contact angle with film (a stable film is present). The results showed that as Young’s contact angle increased, film thickness decreased which leading to increasing of contact angle with film. The effects of CO2-mineral pre-contact have also been investigated and it has been found that on mediate hydrophilic surfaces (Q3), water films were present when CO2 droplets were placed above the surfaces, however, water films were absent when CO2 droplets directly contact with the surfaces. This phenomenon implies that water films on mineral surfaces have a possibility to rupture and a film rupture mechanism for CO2 adhesion on hydrated mineral surfaces was proposed. These results may provide new information on interactions among CO2, water/brine and mineral to better understand the behaviour of CO2 during geologic sequestration. 相似文献