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1.
The effect of elevated carbon dioxide and fertilization on primary and secondary metabolites in birch,Betula pendula (Roth) 总被引:5,自引:0,他引:5
Seedlings of European white birch (Betula pendula Roth) were grown in growth chambers for one growth season under four carbon dioxide regimes (350, 700, 1050 and 1400 ppm) and at three fertilization levels (0, 100 and 500 kg ha–1 monthly). The soluble carbohydrates and secondary phenolics in the leaves and stems were analysed. It was found that fertilizer addition reduced the amounts of glucose and fructose while sucrose remained almost unaffected. The sugar content of leaves increased at 700 ppm and 1050 ppm of CO2 and decreased at the highest CO2 concentration (1400 ppm). The amounts of proanthocyanidins and flavonoids in leaves decreased with fertilization addition and increased with CO2 enrichment. The production of simple phenolic glucosides varied according to the fertilization and CO2 treatments. The triterpenoid content of stems seemed to increase with fertilization and CO2-addition. Our results indicate that the production of phytochemicals in the birch seedlings is very sensitive to both fertilization and CO2 addition, which is in agreement with earlier studies, and thus provide some support for the hypothesis of carbon allocation to plant defence when there is an excess of carbon and nutrient. The considerable variation in the production of secondary components may indicate that the synthesis of these defensive metabolites can be regulated by a plant to certain extent, depending on the ability of the plant to acclimate to changes in the physical environment. 相似文献
2.
Nutrient concentration in shape Sphagna at increased N-deposition rates and raised atmospheric CO2 concentrations 总被引:1,自引:0,他引:1
Sphagnum fuscum, S. magellanicum, S. angustifolium and S. warnstorfii were treated with N deposition rates (0, 10, 30 and 100 kg ha-1 a-1) and with four atmospheric CO2 concentrations (350, 700, 1000 and 2000 ppm) in greenhouse for 71–120 days. Thereafter, concentrations of total N, P, K, Ca and Mg in the capitulae of the Sphagna were determined. The response of each species to N deposition was related to ecological differences. With increasing N deposition treatments, moss N concentrations increased and higher N:P-ratios were found, the increase being especially clear at the highest N load. Sphagnum fuscum, which occupies ombrotrophic habitats, was the most affected by the increased nitrogen load and as a consequence the other elements were decreased. Oligotrophic S. magellanicum, wide nutrient status tolerant S. angustifolium and meso-eutrophic S. warnstorfii tolerated better increased N deposition, though there were increased concentrations of Ca and Mg in S. warnstorfii and Mg in S. magellanicum. Nitrogen and P concentrations decreased with raised CO2 concentrations, except for S. magellanicum. This seems to be the first time this kind of response in nutrient concentrations to enhanced CO2 concentration has been shown to exist in bryophytes. The concentration of K clearly decreased in S. fuscum as did the concentration of Mg in the other Sphagna with increasing CO2. Sphagnum angustifolium and S. magellanicum, which are the less specialized species, were the least affected by the CO2 treatments. 相似文献
3.
Interacting effects of CO2 concentration, temperature and nitrogen supply on the photosynthesis and composition of winter wheat leaves 总被引:2,自引:2,他引:0
E. DELGADO R. A. C. MITCHELL M. A. J. PARRY S. P. DRISCOLL V. J. MITCHELL D. W. LAWLOR 《Plant, cell & environment》1994,17(11):1205-1213
Winter wheat (Triticum aestivum L., cv. Mercia) was grown at two different atmospheric CO2 concentrations (350 and 700 μmol mol−1), two temperatures [ambient temperature (i.e. tracking the open air) and ambient +4°C] and two rates of nitrogen supply (equivalent to 489 kg ha−1 and 87 kg ha−1). Leaves grown at 700 μmol mol−1 CO2 had slightly greater photosynthetic capacity (10% mean increase over the experiment) than those grown at ambient CO2 concentration, but there were no differences in carboxylation efficiency or apparent quantum yield. The amounts of chlorophyll, soluble protein and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) per unit leaf area did not change with long-term exposure to elevated CO2 concentration. Thus winter wheat, grown under simulated field conditions, for which total biomass was large compared to normal field production, did not experience loss of components of the photosynthetic system or loss of photosynthetic competence with elevated CO2 concentration. However, nitrogen supply and temperature had large effects on photosynthetic characteristics but did not interact with elevated CO2 concentration. Nitrogen deficiency resulted in decreases in the contents of protein, including Rubisco, and chlorophyll, and decreased photosynthetic capacity and carboxylation efficiency. An increase in temperature also reduced these components and shortened the effective life of the leaves, reducing the duration of high photosynthetic capacity. 相似文献
4.
The effects of elevated CO2 (ambient, +175, and +350 μl l−1) and nitrogen fertilization (0, 100, and 200 kg N ha−1 yr−1 as ammonium sulfate) on C and N accumulations in biomass and soils planted with ponderosa pine (Pinus ponderosa Laws) over a 6-year study period are reported. Both nitrogen fertilization and elevated CO2 caused increases in C and N contents of vegetation over the study period. The pattern of responses varied over time. Responses
to CO2 decreased in the +175 μl l−1 and increased in the +350 μl l−1 after the first year, whereas responses to N decreased after the first year and became non-significant by year six. Foliar
N concentrations were lower and tree C:N ratios were higher with elevated CO2 in the early years, but this was offset by the increases in biomass, resulting in substantial increases in N uptake with
elevated CO2. Nitrogen budget estimates showed that the major source of the N for unfertilized trees, with or without elevated CO2, was likely the soil organic N pool. There were no effects of elevated CO2 on soil C, but a significant decrease in soil N and an increase in soil C:N ratio in year six. Nitrogen fertilization had
no significant effect on tree C:N ratios, foliar N concentrations, soil C content, soil N content, or soil C:N ratios. There
were no significant interactions between CO2 and N treatments, indicating that N fertilization had no effect on responses to CO2 and that CO2 treatments had no effect on responses to N fertilization. These results illustrate the importance of long-term studies involving
more than one level of treatment to assess the effects of elevated CO2. 相似文献
5.
A study was conducted in the Lower Laurentians of southern Quebec to test the hypothesis that base cation fertilization would improve the nutrient status of declining sugar maples (Acer saccharum Marsh.) and alter the partitioning of leaf C and N. Six 40×40 m plots were delineated in an 80 year old stand of sugar maple. Three plots received a mixture of fertilizer and liming materials (500 kg ha–1 of K2SO4, 250 kg ha–1 of CaCO3 and 250 kg ha–1 of CaMg(CO2)2) in the spring of 1989. Leaves from mid crown of dominant or co-dominant maples were sampled monthly during the 1990 growing season. Trees were cored in 1992 to measure their response in diameter growth. Fertilization increased diameter growth and foliar K concentration of trees but reduced foliar Ca concentration. Fertilization resulted in lower starch concentrations and higher ratios of soluble sugars to starch in June and September, and in higher free amino acid concentrations but lower ratio of total non-structural carbohydrates to free amino acids in September. Leaf proline concentration was correlated with leaf starch concentration (r=0.39). The results suggest that amelioration of K deficiencies in sugar maple through fertilization with a mixture of base cations can increase tree growth and affect the seasonal dynamics of foliar C and N pools.Abbreviations FAA
free amino acids
- TNC
total non-structural carbohydrates 相似文献
6.
Summary Willows (Salix x dasyclados) were grown for 4 months in growth chambers at four nutrient and CO2 levels, and photosynthesis measurements were made during the latter half of this period. Photosynthesis became saturated at lower light intensities at low CO2 concentrations than at higher ones. The effect of CO2 concentration on photosynthesis was greater at higher temperatures. The willows grown at the highest CO2 concentration (1000 ppm) had a lower photosynthetic capacity than the others when measured at various concentrations. The effect of nutrient status on photosynthesis clearly increased with rising CO2 concentrations. Although photosynthetic acclimation took place to a certain extent at higher CO2 concentrations, photosynthesis still remained higher the higher the growth concentration was. At each CO2 level photosynthesis increased contemporaneously with leaf nitrogen content, but at each fertilization level a rise in CO2 concentration slightly increased photosynthesis and reduced the nitrogen content. The relative increase in photosynthesis achieved by a rise in CO2 was greater than the corresponding increase in biomass growth, whereas the effect of fertilization was greater on biomass growth than on the rate of photosynthesis in the same willows. 相似文献
7.
The aim of this study was to analyze the effects of forest management on the total biomass production (t ha-1a-1) and CO2 emissions (kg CO2 MWh-1) from use of energy biomass of Norway spruce and Scots pine grown on a medium fertile site. In this context, the growth of
both species was simulated using an ecosystem model (SIMA) under different management regimes, including various thinning
and fertilization treatments over rotation lengths from 40 to 120 years in different pre-commercial stand densities. A Life
Cycle Analysis/Emission calculation tool was employed to assess the CO2 emissions per unit of energy from the use of biomass in energy production. Furthermore, the overall balance between the CO2 uptake and emission (carbon balance) was studied, and the carbon neutrality (CN) factor was calculated to assess environmental
effects of the use of biomass in energy production; i.e., how much CO2 would be emitted per unit of energy when considering direct and indirect emissions from forest ecosystem and energy production.
In general, the total annual biomass production for both species was highest when management with fertilization and high pre-commercial
stand density (4000–6000 trees ha-1) was used. In the case of Norway spruce, the highest annual biomass production was obtained with a rotation length of 80–100
years, while for Scots pine a rotation length of 40–60 years gave the highest annual production. In general, the CO2 emissions decreased along with an increasing rotation length. The reduction was especially large if the rotation length was
increased from 40 years to 60 years. Scots pine produced remarkably smaller net CO2 emissions per year (on average 29%) than Norway spruce over all different densities and rotation lengths. The value of the
CN factor was highest if a rotation of 100 years was used for Norway spruce stands and a rotation of 120 years for Scots pine.
The CO2 emission per energy unit was substantially less than that from the use of coal, which was used as reference to assess environmental
effects of the use of biomass in energy production. The use of higher density of pre-commercial stand than that currently
recommended in the Finnish forestry, together with timely thinning and fertilization, could increase the total biomass production,
but also simultaneously decrease the net CO2 emissions from the use of energy wood. 相似文献
8.
Summary Sporocarps and sclerotia were collected for a one-year period in 23- and 180-year-old Abies amabilis stands in western Washington. All sporocarps were classified and chemically analyzed for N, P, K, Ca, Mg, Na and Fe. Lactarius sp. and Cortinarius sp. contributed the largest proportion of the total annual epigeous sporocarp production in both stands. Annual epigeous production was 34 kg/ha in the young stand and 27 kg/ha in the mature stand. Hypogeous sporocarp production increased from 1 kg ha-1 yr-1 to 380 kg ha-1 yr-1 with increasing stand age. High sclerotia biomass occurred in the young (2,300 kg/ha) and mature (3,000 kg/ha) stands. Peak sclerotia and epigeous sporocarp biomass in the young stand and epigeous and hypogeous sporocarp biomass in the mature stand coincided with the fall peak of mycorrhizal root biomass.In the young stand, sporocarps produced by decomposer fungi concentrated higher levels of Ca and Mn than those produced by mycorrhizal fungi. In the mature stand, sporocarps of decomposer fungi concentrated higher levels of N, P, Mn, Ca and Fe than sporocarps of mycorrhizal fungi. Epigeous and hypogeous sporocarps concentrated higher levels of N, P, and K than sclerotia or mycelium. The highest concentration of N (4.36%), P (0.76%), K (3.22%) and Na (1,678 ppm) occurred in epigeous sporocarps. Highest Mn (740 ppm) and Ca (20,600 ppm) concentrations occurred in mycelium, while highest Mg (1,929 ppm) concentrations were in hypogeous sporocarps and highest Fe (4,153 ppm) concentrations were in sclerotia. 相似文献
9.
Effects of elevated CO2 on plant growth and nutrient partitioning of rice (Oryza sativa L.) at rapid tillering and physiological maturity 总被引:2,自引:0,他引:2
《Journal of Plant Interactions》2013,8(1):35-42
Abstract This work investigates the relationship between plant growth, grain yield, nutrient acquisition and partitioning in rice (Oryza sativa L.) under elevated CO2. Plants were grown hydroponically in growth chambers with a 12-h photoperiod at either 370 or 700 µmol CO2 mol?1 concentration. Plant dry mass (DM), grain yield and macro- and micronutrient concentrations of vegetative organs and grains were determined. Elevated CO2 increased biomass at tillering, and this was largely due to an increase in root mass by 160%. Elevated CO2 had no effect on total nutrient uptake (N, P, K, Mg and Ca). However, nutrient partitioning among organs was significantly altered. N partitioning to leaf blades was significantly decreased, whereas the N partitioning into the leaf sheaths and roots was increased. Nutrient use efficiency of N, P, K, and Mg in all organs was significantly increased at elevated CO2. At harvest maturity, grain yield was increased by 27% at elevated CO2 while grain (protein) concentration was decreased by a similar magnitude (28%), suggesting that critical nutrient requirements for rice might need to be reassessed with global climate change. 相似文献
10.
Implications of productivity and nutrient requirements on greenhouse gas balance of annual and perennial bioenergy crops 总被引:1,自引:0,他引:1
Stephane Cadoux Fabien Ferchaud Charlotte Demay Hubert Boizard Jean‐Marie Machet Emilie Fourdinier Matthieu Preudhomme Brigitte Chabbert Ghislain Gosse Bruno Mary 《Global Change Biology Bioenergy》2014,6(4):425-438
Biomass from dedicated crops is expected to contribute significantly to the replacement of fossil resources. However, sustainable bioenergy cropping systems must provide high biomass production and low environmental impacts. This study aimed at quantifying biomass production, nutrient removal, expected ethanol production, and greenhouse gas (GHG) balance of six bioenergy crops: Miscanthus × giganteus, switchgrass, fescue, alfalfa, triticale, and fiber sorghum. Biomass production and N, P, K balances (input‐output) were measured during 4 years in a long‐term experiment, which included two nitrogen fertilization treatments. These results were used to calculate a posteriori ‘optimized’ fertilization practices, which would ensure a sustainable production with a nil balance of nutrients. A modified version of the cost/benefit approach proposed by Crutzen et al. (2008), comparing the GHG emissions resulting from N‐P‐K fertilization of bioenergy crops and the GHG emissions saved by replacing fossil fuel, was applied to these ‘optimized’ situations. Biomass production varied among crops between 10.0 (fescue) and 26.9 t DM ha?1 yr?1 (miscanthus harvested early) and the expected ethanol production between 1.3 (alfalfa) and 6.1 t ha?1 yr?1 (miscanthus harvested early). The cost/benefit ratio ranged from 0.10 (miscanthus harvested late) to 0.71 (fescue); it was closely correlated with the N/C ratio of the harvested biomass, except for alfalfa. The amount of saved CO2 emissions varied from 1.0 (fescue) to 8.6 t CO2eq ha?1 yr?1 (miscanthus harvested early or late). Due to its high biomass production, miscanthus was able to combine a high production of ethanol and a large saving of CO2 emissions. Miscanthus and switchgrass harvested late gave the best compromise between low N‐P‐K requirements, high GHG saving per unit of biomass, and high productivity per hectare. 相似文献
11.
Effects of elevated atmospheric carbon dioxide (CO2) levels on the production and spread of ectomycorrhizal fungal mycelium from colonised Scots pine roots were investigated. Pinus sylvestris (L.) Karst. seedlings inoculated with either Hebeloma crustuliniforme (Bull:Fr.) Quél. or Paxillus involutus (Fr.) Fr. were grown at either ambient (350 ppm) or elevated (700 ppm) levels of CO2. Mycelial production was measured after 6 weeks in pots, and mycelial spread from inoculated seedlings was studied after 4 months growth in perlite in shallow boxes containing uncolonised bait seedlings. Plant and fungal biomass were analysed, as well as carbon and nitrogen content of seedling shoots. Mycelial biomass production by H. crustuliniforme was significantly greater under elevated CO2 (up to a 3-fold increase was observed). Significantly lower concentrations and total amounts of N were found in plants exposed to elevated CO2. 相似文献
12.
Influence of elevated CO2 and nitrogen nutrition on rice plant growth,soil microbial biomass,dissolved organic carbon and dissolved CH4 总被引:1,自引:0,他引:1
Rice (Oryza sativa) was grown in six sunlit, semi-closed growth chambers for two seasons at 350 L L–1 (ambient) and 650 L L–1 (elevated) CO2 and different levels of nitrogen (N) supplement. The objective of this research was to study the influence of CO2 enrichment and N nutrition on rice plant growth, soil microbial biomass, dissolved organic carbon (DOC) and dissolved CH4. Elevated CO2 concentration ([CO2]) demonstrated a wide range of enhancement to both above- and below-ground plant biomass, in particular to stems and roots (for roots when N was not limiting) in the mid-season (80 days after transplanting) and stems/ears at the final harvest, depending on season and the level of N supplement. Elevated [CO2] significantly increased microbial biomass carbon in the surface 5 cm soil when N (90 kg ha–1) was in sufficient supply. Low N supplement (30 kg ha–1) limited the enhancement of root growth by elevated [CO2], leading consequently to diminished response of soil microbial biomass carbon to CO2 enrichment. The concentration of dissolved CH4 (as well as soil DOC, but to a lesser degree) was observed to be positively related to elevated [CO2], especially at high rate of N application (120 kg ha–1) or at 10 cm depth (versus 5 cm depth) in the later half of the growing season (at 80 kg N ha–1). Root senescence in the late season complicated the assessment of the effect of elevated [CO2] on root growth and soil organic carbon turnover and thus caution should be taken when interpreting respective high CO2 results. 相似文献
13.
The aim of this work was to examine the response of wheat plants to a doubling of the atmospheric CO2 concentration on: (1) carbon and nitrogen partitioning in the plant; (2) carbon release by the roots; and (3) the subsequent N uptake by the plants. The experiment was performed in controlled laboratory conditions by exposing fast-growing spring wheat plants, during 28 days, to a 14CO2 concentration of 350 or 700 L L–1 at two levels of soil nitrogen fertilization. Doubling CO2 availability increased total plant production by 34% for both N treatment. In the N-fertilized soil, the CO2 enrichment resulted in an increase in dry mass production of 41% in the shoots and 23% in the roots; without N fertilization this figure was 33% and 37%, respectively. In the N-fertilized soil, the CO2 increase enhanced the total N uptake by 14% and lowered the N concentration in the shoots by 23%. The N concentration in the roots was unchanged. In the N-fertilized soil, doubling CO2 availability increased N uptake by 32% but did not change the N concentrations, in either shoots or roots. The CO2 enrichment increased total root-derived carbon by 12% with N fertilization, and by 24% without N fertilization. Between 85 and 90% of the total root derived-14C came from respiration, leaving only 10 to 15% in the soil as organic 14C. However, when total root-derived 14C was expressed as a function of root dry weight, these differences were only slightly significant. Thus, it appears that the enhanced carbon release from the living roots in response to increased atmospheric CO2, is not due to a modification of the activity of the roots, but is a result of the increased size of the root system. The increase of root dry mass also resulted in a stimulation of the soil N mineralization related to the doubling atmospheric CO2 concentration. The discussion is focused on the interactions between the carbon and nitrogen allocation, especially to the root system, and the implications for the acquisition of nutrients by plants in response to CO2 increase.Abbreviations N
soil fertilization without nitrogen
- N
soil fertilization with nitrogen 相似文献
14.
M. K. Kering J. T. Biermacher T. J. Butler J. Mosali J. A. Guretzky 《Bioenergy Research》2012,5(1):71-78
Increasing desire for renewable energy sources has increased research on biomass energy crops in marginal areas with low potential for food and fiber crop production. In this study, experiments were established on low phosphorus (P) soils in southern Oklahoma, USA to determine switchgrass biomass yield, nutrient concentrations, and nutrient removal responses to P and nitrogen (N) fertilizer application. Four P rates (0, 15, 30, and 45?kg?P?ha?1) and two N fertilizer rates (0 and 135?kg?N?ha?1) were evaluated at two locations (Ardmore and Waurika) for 3?years. While P fertilization had no effect on yield at Ardmore, application of 45?kg?P?ha?1 increased yield at Waurika by 17% from 10.5 to 12.3?Mg?ha?1. Across P fertilizer rates, N fertilizer application increased yields every year at both locations. In Ardmore, non-N-fertilized switchgrass produced 3.9, 6.7, and 8.8?Mg?ha?1, and N-fertilized produced 6.6, 15.7, and 16.6?Mg?ha?1 in 2008, 2009, and 2010, respectively. At Waurika, corresponding yields were 7.9, 8.4, and 12.2?Mg?ha?1 and 10.0, 12.1, and 15.9?Mg?ha?1. Applying 45?kg?P?ha?1 increased biomass N, and P concentration and N, P, potassium, and magnesium removal at both locations. Increased removal of nutrients with N fertilization was due to both increased biomass and biomass nutrient concentrations. In soils of generally low fertility and low plant available P, application of P fertilizer at 45?kg?P?ha?1 was beneficial for increasing biomass yields. Addition of N fertilizer improves stand establishment and biomass production on low P sites. 相似文献
15.
Perennial ryegrass swards were grown in large containers on a soil and were exposed during two years to elevated (700 L L-1) or ambient atmospheric CO2 concentration at outdoor temperature and to a 3 °C increase in air temperature in elevated CO2. The nitrogen nutrition of the grass sward was studied at two sub-optimal (160 and 530 kg N ha-1 y-1) and one non-limiting (1000 kg N ha-1 y-1) N fertilizer supplies. At cutting date, elevated CO2 reduced by 25 to 33%, on average, the leaf N concentration per unit mass. Due to an increase in the leaf blade weight per unit area in elevated CO2, this decline did not translate for all cuts in a lower N concentration per unit leaf blade area. With the non-limiting N fertilizer supply, the leaf N concentration (% N) declined with the shoot dry-matter (DM) according to highly significant power models in ambient (% N=4.9 DM-0.38) and in elevated (%N=5.3 DM-0.52) CO2. The difference between both regressions was significant and indicated a lower critical leaf N concentration in elevated than in ambient CO2 for high, but not for low values of shoot biomass. With the sub-optimal N fertilizer supplies, the nitrogen nutrition index of the grass sward, calculated as the ratio of the actual to the critical leaf N concentration, was significantly lowered in elevated CO2. This indicated a lower inorganic N availability for the grass plants in elevated CO2, which was also apparent from the significant declines in the annual nitrogen yield of the grass sward and in the nitrate leaching during winter. For most cuts, the harvested fraction of the plant dry-matter decreased in elevated CO2 due, on average, to a 45–52% increase in the root phytomass. In the same way, a smaller share of the plant total nitrogen was harvested by cutting, due, on average, to a 25–41% increase in the N content of roots. The annual means of the DM and N harvest indices were highly correlated to the annual means of the nitrogen nutrition index. Changes in the harvest index and in the nitrogen nutrition index between ambient and elevated CO2 were also positively correlated. The possible implication of changes in the soil introgen cycle and of a limitation in the shoot growth potential of the grass in elevated. CO2 is discussed.Abbreviations 350
outdoor climate
- 700
outdoor climate +350 L L-1[CO2]
- 700+
outdoor climate +350 L L-1 (CO2) and +3 °C
- N--
low N fertilizer supply
- N+
high N fertilizer supply
- N++
non-limiting N fertilizer supply
- DM
dry-matter 相似文献
16.
Understanding the effects of nitrogen (N) fertilization on Miscanthus × giganteus greenhouse gas emissions, nitrate leaching, and biomass production is an important consideration when using this grass as a biomass feedstock. The objective of this study was to determine the effect of three N fertilization rates (0, 60, and 120?kg?N?ha?1 using urea as the N source) on nitrous oxide (N2O) and carbon dioxide (CO2) emissions, nitrogen leaching, and the biomass yields and N content of M. × giganteus planted in July 2008, and evaluated from 2009 through early 2011 in Urbana, Illinois, USA. While there was no biomass yield response to N fertilization rates in 2009 and 2010, the amount of N in the harvested biomass in 2010 was significantly greater at the 60 and 120?kg?N?ha?1?N rates. There was no significant CO2 emission response to N rates in 2009 or 2010. Similarly, N fertilization did not increase cumulative N2O emissions in 2009, but cumulative N2O emissions did increase in 2010 with N fertilization. During 2009, nitrate (NO 3 ? ) leaching at the 50-cm soil depth was not related to fertilization rate, but there was a significant increase in NO 3 ? leaching between the 0 and 120?kg?N?ha?1 treatments in 2010 (8.9 and 28.9?kg?NO3?CN?ha?1?year?1, respectively). Overall, N fertilization of M. × giganteus led to N2O releases, increased fluxes of inorganic N (primarily NO 3 ? ) through the soil profile; and increased harvested N without a significant increase in biomass production. 相似文献
17.
The Hurley Pasture Model was used to examine the short and long-term responses of grazed grasslands in the British uplands to a step increase from 350 to 700 μmol mol–1 CO2 concentration ([CO2]) with inputs of 5 or 100 kg N ha–1 y–1. In N-rich grassland, [CO2] doubling quickly increased net primary productivity (NPP), total carbon (Csys) and plant biomass by about 30%. By contrast, the N-poor grassland underwent a prolonged ‘transient’, when there was little response, but eventually NPP, Csys and plant biomass more than doubled. The ‘transient’ was due to N immobilization and severe depletion of the soil mineral N pool. The large long-term response was due to slow N accumulation, as a result of decreased leaching, decreased gaseous N losses and increased N2-fixation, which amplified the CO2 response much more in the N-poor than in the N-rich grassland. It was concluded that (i) ecosystems use extra carbon fixed at high [CO2] to acquire and retain nutrients, supporting the contention of Gifford et al. (1996 ), (ii) in the long term, and perhaps on the real timescale of increasing [CO2], the response (in NPP, Csys and plant biomass) of nutrient-poor ecosystems may be proportionately greater than that of nutrient-rich ones, (iii) short-term experiments on nutrient-poor ecosystems may observe only the transient responses, (iv) the speed of ecosystem responses may be limited by the rate of nutrient accumulation rather than by internal rate constants, and (v) ecosystem models must represent processes affecting nutrient acquisition and retention to be able to simulate likely real-world CO2 responses. 相似文献
18.
Effects of CO2 and nitrogen fertilization on vegetation and soil nutrient content in juvenile ponderosa pine 总被引:3,自引:0,他引:3
This paper summarizes the data on nutrient uptake and soil responses in opentop chambers planted with ponderosa pine (Pinus ponderosa Laws.) treated with both N and CO2. Based upon the literature, we hypothesized that 1) elevated CO2 would cause increased growth and yield of biomass per unit uptake of N even if N is limiting, and 2) elevated CO2 would cause increased biomass yield per unit uptake of other nutrients only by growth dilution and only if they are non-limiting. Hypothesis 1 was supported only in part: there were greater yields of biomass per unit N uptake in the first two years of growth but not in the third year. Hypothesis 2 was supported in many cases: elevated CO2 caused growth dilution (decreased concentrations but not decreased uptake) of P, S, and Mg. Effects of elevated CO2 on K, Ca, and B concentrations were smaller and mostly non-significant. There was no evidence that N responded in a unique manner to elevated CO2, despite its unique role in rubisco. Simple growth dilution seemed to explain nutrient responses in almost all cases.There were significant declines in soil exchangeable K+, Ca2+, Mg2+ and extractable P over time which were attributed to disturbance effects associated with plowing. The only statistically significant treatment effects on soils were negative effects of elevated CO2 on mineralizeable N and extractable P, and positive effects of both N fertilization and CO2 on exchangeable Al3+. Soil exchangeable K+, Ca2+, and Mg2+ pools remained much higher than vegetation pools, but extractable P pools were lower than vegetation pools in the third year of growth. There were also large losses of both native soil N and fertilizer N over time. These soil N losses could account for the observed losses in exchangeable K+, Ca2+, Mg2+ if N was nitrified and leached as NO
3
–
. 相似文献
19.
Effect of elevated CO2 concentration on seedling growth rate and photosynthesis inHevea brasiliensis
A. S. Devakumar M. S. Shesha Shayee M. Udayakumar T. G. Prasad 《Journal of biosciences》1998,23(1):33-36
To study the effect of elevated CO2 concentration on plant growth and photosynthesis, two clones ofHevea brasiliensis were grown in polybags and exposed to elevated concentration (700±25ppm) for 60 days. There was higher biomass accumulation,
leaf area and better growth when compared to ambient air grown plantso From A/Ci curves it is clear that photosynthetic rates
increases with increase in CO2 concentrations. After 60 days of exposure to higher CO2 concentration, a decrease in the carbon assimilation rate was noticed. 相似文献
20.
Root dynamics in a semi-natural grassland in relation to atmospheric carbon dioxide enrichment,soil water and shoot biomass 总被引:1,自引:0,他引:1
Sindhøj Erik Hansson Ann-Charlotte Andrén Olof Kätterer Thomas Marissink Mark Pettersson Roger 《Plant and Soil》2000,223(1-2):255-265
Plant responses to increasing atmospheric CO2 concentrations have been studied intensively. However, the effects of elevated CO2 on root dynamics, which is important for global carbon budgets as well as for nutrient cycling in ecosystems, has received
much less attention. We used minirhizotrons inside open-top chambers to study the effects of elevated atmospheric carbon dioxide
concentration on root dynamics in a nutrient-poor semi-natural grassland in central Sweden. We conducted our investigation
over three consecutive growing seasons during which three treatments were applied at the site: Elevated (≈ 700 μmol mol-1) and ambient (≈ 360 μmol mol-1) chamber levels of CO2 and a control, without a chamber. During 1997, a summer with two dry periods, the elevated treatment compared with ambient
had 25% greater mean root counts, 65% greater above-ground biomass and 15% greater soil moisture. The chambers seemed responsible
for changes in root dynamics, whereas the elevated CO2 treatment in general increased the absolute sum of root counts compared with the ambient chamber. In 1998, a wet growing
season, there were no significant differences in shoot biomass or root dynamics and both chamber treatments had lower soil
moisture than the control. We found that as seasonal dryness increased, the ratio of elevated – ambient shoot biomass production
increased while the root to shoot ratio decreased. We conclude that this grasslands response to elevated CO2 is dependent on seasonal weather conditions and that CO2 enrichment will most significantly increase production in such a grassland when under water stress.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献