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  • Nitrogen  (4)
  • Storage  (3)
  • 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry  (2)
  • Canopy conductance  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 70 (1986), S. 466-474 
    ISSN: 1432-1939
    Keywords: Biennial plants ; Carbon partitioning ; Nitrogen partitioning ; Storage ; Harvest index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Growth and nitrogen partitioning were investigated in the biennial monocarp Arctium tomentosum in the field, in plants growing at natural light conditions, in plants in which approximately half the leaf area was removed and in plants growing under 20% of incident irradiation. Growth quantities were derived from splined cubic polynomial exponential functions fitted to dry matter, leaf area and nitrogen data. Main emphasis was made to understanding of the significance of carbohydrate and nitrogen storage of a large tuber during a 2-years' life cycle, especially the effect of storage on biomass and seed yield in the second season. Biomass partitioning favours growth of leaves in the first year rosette stage. Roots store carbohydrates at a constant rate and increase storage of carbohydrates and nitrogen when the leaves decay at the end of the first season. In the second season the reallocation of carbohydrates from storage is relatively small, but reallocation of nitrogen is very large. Carbohydrate storage just primes the growth of the first leaves in the early growing season, nitrogen storage contributes 20% to the total nitrogen requirement during the 2nd season. The efficiency of carbohydrate storage for conversion into new biomass is about 40%. Nitrogen is reallocated 3 times in the second year, namely from the tuber to rosette leaves and further to flower stem leaves and eventually into seeds. The harvest index for nitrogen is 0.73, whereas for biomass it is only 0.19.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1939
    Keywords: Carbohydrate ; Growth ; Nitrogen ; Phaseolus lunatus ; Storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth, photosynthesis, and storage of nitrogen (N) and total non-structural carbohydrates (TNC) of a perennial wild type and an annual cultivar of lima bean (Phaseolus lunatus) were examined at different light intensities and N supplies. Relative growth rate and photosynthesis increased with light and N availability. N limitation enhanced biomass allocation into root rather than into shoot, while light limitation enhanced growth of leaf area. The TNC concentrations increased with light intensity and thus with photosynthesis, while the concentrations of organic N and nitrate decreased. Increasing N supply had the opposite effect. Therefore, TNC and organic N concentrations were negatively correlated (r=−0.90). Pool size of N or TNC increased with N and light availability when either resource was non-limiting, but increased little or remained constant when either resource was limiting. Storage reached a minimum when both resources were supplied at an equal rate.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1939
    Keywords: Mimicry ; Nitrogen ; Herbivory ; Mistletoe ; Australia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Leaves from many misletoe species in Australia strongly resemble those of their hosts. This cryptic mimicry has been hypothesized to be a means of reducing the likelihood of mistletoe herbivory by vertebrates. Leaf Kjeldahl nitrogen contents (a measure of reduced nitrogen and thus amines, amino acids and protein levels) of mistletoes and their hosts were measured on 48 mimetic and nonmimetic host-parasite pairs to evaluate hypotheses concerning the significance of crysis versus noncrypsis. The hypothesis that mistletoes mimicking host leaves should have higher leaf nitrogen levels than their hosts is supported; they may be gaining a selective advantage through crypsis (reduced herbivory). The second hypothesis that mistletoes which do not mimic their hosts should have lower leaf nitrogen levels than their hosts is also supported; they may be gaining a selective advantage through noncrypsis (reduced herbivory resulting from visual advertisement of their reduced nutritional status).
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1939
    Keywords: Forest decline, Spruce (Picea abies) ; Nitrogen ; Magnesium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A declining Picea abies (L.) Karst. stand produced as much foliage and branches as a healthy stand but less stemwood at a similar leaf area index and climate. Nutrient analyses revealed that most biomass components at the declining site had lower concentrations of calcium and magnesium, but similar nitrogen and potassium (except for lower potassium in younger needles) and higher phosphorus, manganese and aluminum than the respective components at the healthy site. Comparison of these data with the results from studies on the nutrition and growth of P. abies seedlings (Ingestad 1959) led to the conclusion that the healthy stand is in a balanced nutritional state, while trees at the declining stand have only 56% of the foliar magnesium concentration required to permit growth at a rate which could be achieved at their nitrogen status. It appears that acidic deposition, which involves an input of nitrogen and a leaching of cations from the soil, causes an imbalance in the availability of nitrogen and magnesium. Growth is eventually reduced as magnesium becomes limiting.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1939
    Keywords: Storage ; Accumulation ; Reserve formation ; Storage structure ; Biennial plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four biennial species (Arctium tomentosum, Cirsium vulgare, Dipsacus sylvester and Daucus carota) which originate from habitats of different nutrient availability were investigated in a 2-year experiment in a twofactorial structured block design varying light (natural daylight versus shading) and fertilizer addition. The experiment was designed to study storage as reserve formation (competing with growth) or as accumulation (see Chapin et al. 1990). We show that (i) the previous definitions of storage excluded an important process, namely the formation of storage tissue. Depending on species, storage tissue and the filling process can be either a process of reserve formation, or a process of accumulation. (ii) In species representing low-resource habitats, the formation of a storage structure competes with other growth processes. Growth of storage tissue and filling with storage products is an accumulation process only in the high-resource plant Arctium tomentosum. We interpret the structural growth of low-resource plants in terms of the evolutionary history of these species, which have closely related woody species in the Mediterranean area. (iii) The use of storage products for early leaf growth determines the biomass development in the second season and the competitive ability of this species during growth with perennial species. (iv) The high-resource plant Arctium has higher biomass development under all conditions, i.e. plants of low-resource habitats are not superior under low-resource conditions. The main difference between high- and low-resource plants is that low-resource plants initiate flowering at a lower total plant internal pool size of available resources.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 95 (1993), S. 153-163 
    ISSN: 1432-1939
    Keywords: Evaporation ; Aerodynamic conductance ; Canopy conductance ; Humidity response ; Soil water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Canopy-scale evaporation rate (E) and derived surface and aerodynamic conductances for the transfer of water vapour (gs and ga, respectively) are reviewed for coniferous forests and grasslands. Despite the extremes of canopy structure, the two vegetation types have similar maximum hourly evaporation rates (E max) and maximum surface conductances (gsmax) (medians = 0.46 mm h-1 and 22 mm s-1). However, on a daily basis, median E max of coniferous forest (4.0 mm d-1) is significantly lower than that of grassland (4.6 mm d-1). Additionally, a representative value of ga for coniferous forest (200 mm s-1) is an order of magnitude more than the corresponding value for grassland (25 mm s-1). The proportional sensitivity of E, calculated by the Penman-Monteith equation, to changes in gs is 〉0.7 for coniferous forest, but as low as 0.3 for grassland. The proportional sensitivity of E to changes in ga is generally ±0.15 or less. Boundary-line relationships between gs and light and air saturation deficit (D) vary considerably. Attainment of gsmax occurs at a much lower irradiance for coniferous forest than for grassland (15 versus about 45% of full sunlight). Relationships between gs and D measured above the canopy appear to be fairly uniform for coniferous forest, but are variable for grassland. More uniform relationships may be found for surfaces with relatively small ga, like grassland, by using D at the evaporating surface (D0) as the independent variable rather than D at a reference point above the surface. An analytical expression is given for determining D0 from measurable quantities. Evaporation rate also depends on the availability of water in the root zone. Below a critical value of soil water storage, the ratio of evaporation rate to the available energy tends to decrease sharply and linearly with decreasing soil water content. At the lowest value of soil water content, this ratio declines by up to a factor of 4 from the non-soil-water-limiting plateau. Knowledge about functional rooting depth of different plant species remains rather limited. Ignorance of this important variable makes it generally difficult to obtain accurate estimates of seasonal evaporation from terrestrial ecosystems.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1939
    Keywords: Canopy conductance ; Canopy transpiration ; Xylem sap flow ; Humidity response of stomatal ; Nothofagus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tree transpiration was determined by xylem sap flow and eddy correlation measurements in a temperate broad-leaved forest of Nothofagus in New Zealand (tree height: up to 36 m, one-sided leaf area index: 7). Measurements were carried out on a plot which had similar stem circumference and basal area per ground area as the stand. Plot sap flux density agreed with tree canopy transpiration rate determined by the difference between above-canopy eddy correlation and forest floor lysimeter evaporation measurements. Daily sap flux varied by an order of magnitude among trees (2 to 87 kg day−1 tree−1). Over 50% of plot sap flux density originated from 3 of 14 trees which emerged 2 to 5 m above the canopy. Maximum tree transpiration rate was significantly correlated with tree height, stem sapwood area, and stem circumference. Use of water stored in the trees was minimal. It is estimated that during growth and crown development, Nothofagus allocates about 0.06 m of circumference of main tree trunk or 0.01 m2 of sapwood per kg of water transpired over one hour. Maximum total conductance for water vapour transfer (including canopy and aerodynamic conductance) of emergent trees, calculated from sap flux density and humidity measurements, was 9.5 mm s−1 that is equivalent to 112 mmol m−2 s−1 at the scale of the leaf. Artificially illuminated shoots measured in the stand with gas exchange chambers had maximum stomatal conductances of 280 mmol m−2 s−1 at the top and 150 mmol m−2 s−1 at the bottom of the canopy. The difference between canopy and leaf-level measurements is discussed with respect to effects of transpiration on humidity within the canopy. Maximum total conductance was significantly correlated with leaf nitrogen content. Mean carbon isotope ratio was −27.76±0.27‰ (average ±s.e.) indicating a moist environment. The effects of interactions between the canopy and the atmosphere on forest water use dynamics are shown by a fourfold variation in coupling of the tree canopy air saturation deficit to that of the overhead atmosphere on a typical fine day due to changes in stomatal conductance.
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  • 8
    ISSN: 1432-2048
    Keywords: Nicotiana (photosynthesis) ; Nitrogen ; Photosynthesis (control analysis) ; Ribulose-1,5-bisphosphate carboxylase-oxygenase ; Transgenic plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of nitrogen supply during growth on the contribution of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco; EC 4.1.1.39) to the control of photosynthesis was examined in tobacco (Nicotiana tabacum L.). Transgenic plants transformed with antisense rbcS to produce a series of plants with a progressive decrease in the amount of Rubisco were used to allow the calculation of the flux-control coefficient of Rubisco for photosynthesis (CR). Several points emerged from the data: (i) The strength of Rubisco control of photosynthesis, as measured by CR, was altered by changes in the short-term environmental conditions. Generally, CR was increased in conditions of increased irradiance or decreased CO2. (ii) The amount of Rubisco in wild-type plants was reduced as the nitrogen supply during growth was reduced and this was associated with an increase in CR. This implied that there was a specific reduction in the amount of Rubisco compared with other components of the photosynthetic machinery. (iii) Plants grown with low nitrogen and which had genetically reduced levels of Rubisco had a higher chlorophyll content and a lower chlorophyll a/b ratio than wild-type plants. This indicated that the nitrogen made available by genetically reducing the amount of Rubisco had been re-allocated to other cellular components including light-harvesting and electron-transport proteins. It is argued that there is a “luxury” additional investment of nitrogen into Rubisco in tobacco plants grown in high nitrogen, and that Rubisco can also be considered a nitrogen-store, all be it one where the opportunity cost of the nitrogen storage is higher than in a non-functional storage protein (i.e. it allows for a slightly higher water-use efficiency and for photosynthesis to respond to temporarily high irradiance).
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  • 9
    Publication Date: 2020-12-09
    Description: Climate change negotiations aim to reduce net greenhouse-gas emissions by encouraging direct reductions of emissions and crediting countries for their terrestrial greenhouse-gas sinks. Ecosystem carbon dioxide uptake has offset nearly 10% of Europe’s fossil fuel emissions, but not all of this may be creditable under the rules of the Kyoto Protocol. Although this treaty recognizes the importance of methane and nitrous oxide emissions, scientific research has largely focused on carbon dioxide. Here we review recent estimates of European carbon dioxide, methane and nitrous oxide fluxes between 2000 and 2005, using both top-down estimates based on atmospheric observations and bottom-up estimates derived from ground-based measurements. Both methods yield similar fluxes of greenhouse gases, suggesting that methane emissions from feedstock and nitrous oxide emissions from arable agriculture are fully compensated for by the carbon dioxide sink provided by forests and grasslands. As a result, the balance for all greenhouse gases across Europe’s terrestrial biosphere is near neutral, despite carbon sequestration in forests and grasslands. The trend towards more intensive agriculture and logging is likely to make Europe’s land surface a significant source of greenhouse gases. The development of land management policies which aim to reduce greenhouse-gas emissions should be a priority.
    Description: Published
    Description: 842-850
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: carbon budget ; carbon dioxide ; methane ; greenhouse gas emission ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2021-01-11
    Description: Globally, terrestrial ecosystems have absorbed about 30% of anthropogenic greenhouse gas emissions over the period 2000–2007 and inter-hemispheric gradients indicate that a significant fraction of terrestrial carbon sequestration must be north of the Equator. We present a compilation of the CO2, CO, CH4 and N2O balances of Europe following a dual constraint approach in which (1) a landbased balance derived mainly from ecosystem carbon inventories and (2) a land-based balance derived from flux measurements are compared to (3) the atmospheric data-based balance derived from inversions constrained by measurements of atmospheric GHG (greenhouse gas) concentrations. Good agreement between the GHG balances based on fluxes (1294±545 Tg C in CO2-eq yr−1), inventories (1299±200 Tg C in CO2-eq yr−1) and inversions (1210±405 Tg C in CO2-eq yr−1) increases our confidence that the processes underlying the European GHG budget are well understood and reasonably sampled. However, the uncertainty remains large and largely lacks formal estimates. Given that European net land to atmosphere exchanges are determined by a few dominant fluxes, the uncertainty of these key components needs to be formally estimated before efforts could be made to reduce the overall uncertainty. The net land-to-atmosphere flux is a net source for CO2, CO, CH4 and N2O, because the anthropogenic emissions by far exceed the biogenic sink strength. The dual-constraint approach confirmed that the European biogenic sink removes as much as 205±72 Tg C yr−1 from fossil fuel burning from the atmosphere. However, This C is being sequestered in both terrestrial and inland aquatic ecosystems. If the C-cost for ecosystem management is taken into account, the net uptake of ecosystems is estimated to decrease by 45% but still indicates substantial C-sequestration. However, when the balance is extended from CO2 towards the main GHGs, C-uptake by terrestrial and aquatic ecosystems is offset by emissions of non-CO2 GHGs. As such, the European ecosystems are unlikely to contribute to mitigating the effects of climate change.
    Description: Published
    Description: 3357–3380
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: carbon dioxide ; methane ; soil ; ecosystems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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