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  • 1
    Electronic Resource
    Electronic Resource
    Terrestrial carbon storage resulting from CO2 and nitrogen fertilization in temperate grasslands (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. A temperate grassland model has been used to simulate carbon sequestration under various environmental conditions. The results suggest that the CO2 and nitrogen fertilization that has occurred may contribute appreciably to the so-called missing carbon sink, which it has been suggested must exist to balance the global carbon budget.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb00972.x
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  • 2
    Electronic Resource
    Electronic Resource
    Temperate forest responses to carbon dioxide, temperature and nitrogen: a model analysis (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The ITE Edinburgh Forest Model, which describes diurnal and seasonal changes in the pools and fluxes of C, N and water in a fully coupled forest–soil system, was parametrized to simulate a managed conifer plantation in upland Britain. The model was used to examine (i) the transient effects on forest growth of an IS92a scenario of increasing [CO2] and temperature over two future rotations, and (ii) the equilibrium (sustainable) effects of all combinations of increases in [CO2] from 350 to 550 and 750 μmol mol−1, mean annual temperature from 7.5 to 8.5 and 9.5°C and annual inputs of 20 or 40 kg N ha−1. Changes in underlying processes represented in the model were then used to explain the responses. Eight conclusions were supported by the model for this forest type and climate.〈list xml:id="l1" style="custom"〉1Increasing temperatures above 3°C alone may cause forest decline owing to water stress.2Elevated [CO2] can protect trees from water stress that they may otherwise suffer in response to increased temperature.3In N-limiting conditions, elevated [CO2] can increase allocation to roots with little increase in leaf area, whereas in N-rich conditions elevated [CO2] may not increase allocation to roots and generally increases leaf area.4Elevated [CO2] can decrease water use by forests in N-limited conditions and increase water use in N-rich conditions.5Elevated [CO2] can increase forest productivity even in N-limiting conditions owing to increased N acquisition and use efficiency.6Rising temperatures (along with rising [CO2]) may increase or decrease forest productivity depending on the supply of N and changes in water stress.7Gaseous losses of N from the soil can increase or decrease in response to elevated [CO2] and temperature.8Projected increases in [CO2] and temperature (IS92a) are likely to increase net ecosystem productivity and hence C sequestration in temperate forests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00012.x
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  • 3
    Electronic Resource
    Electronic Resource
    The high-latitude terrestrial carbon sink: a model analysis (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Global change biology 6 (2000), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: A dynamic, global vegetation model, hybrid v4.1 (Friend et al. 1997), was driven by transient climate output from the UK Hadley Centre GCM (HadCM2) with the IS92a scenario of increasing atmospheric CO2 equivalent, sulphate aerosols and predicted patterns of atmospheric N deposition. Changes in areas of vegetation types and carbon storage in biomass and soils were predicted for areas north of 50°N from 1860 to 2100. Hybrid is a combined biogeochemical, biophysical and biogeographical model of natural, potential ecosystems. The effect of periodic boreal forest fires was assessed by adding a simple stochastic fire model. Hybrid represents plant physiological and soil processes regulating the carbon, water and N cycles and competition between individuals of parameterized generalized plant types. The latter were combined to represent tundra, temperate grassland, temperate/mixed forest and coniferous forest. The model simulated the current areas and estimated carbon stocks in the four vegetation types.It was predicted that land areas above 50°N (about 23% of the vegetated global land area) are currently accumulating about 0.4 PgC y−1 (about 30% of the estimated global terrestrial sink) and that this sink could grow to 0.8–1.0 PgC y−1 by the second half of the next century and persist undiminished until 2100. This sink was due mainly to an increase in forest productivity and biomass in response to increasing atmospheric CO2, temperature and N deposition, and includes an estimate of the effect of boreal forest fire, which was estimated to diminish the sink approximately by the amount of carbon emitted to the atmosphere during fires. Averaged over the region, N deposition contributed about 18% to the sink by the 2080 s. As expected, climate change (temperature, precipitation, solar radiation and saturation pressure deficit) and N deposition without increasing atmospheric CO2 produced a carbon source. Forest areas expanded both south and north, halving the current tundra area by 2100. This expansion contributed about 30% to the sink by the 2090 s. Tundra areas which were not invaded by forest fluctuated from sink to source. It was concluded that a high latitude carbon sink exists at present and, even assuming little effect of N deposition, no forest expansion and continued boreal forest fires, the sink is likely to persist at its current level for a century.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2000.00302.x
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  • 4
    Electronic Resource
    Electronic Resource
    N-poor ecosystems may respond more to elevated [CO2] than N-rich ones in the long term. A model analysis of grassland. (1998)
    Oxford, UK : Blackwell Science, Ltd
    Global change biology 4 (1998), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1998.00167.x
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  • 5
    Electronic Resource
    Electronic Resource
    The Impact of the Anomalous Weather of 1995 on the U.K. Economy (2000)
    Springer
    Climatic change 44 (2000), S. 1-26 
    Details
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This study assesses selected impacts on tertiary activities of the anomalously hot summer of 1995 and warm period from November 1994 through October 1995 in the U.K. Over this period, the mean Central England temperature was 1.6 °C above the 1961–1990 normal, representing the highest mean 12-month temperature since the start of the Central England temperature record in 1659. The study is distinguished by its breadth of coverage, for it includes tertiary sectors and activities. Although impacts in tertiary activities are often not included in assessments of the potential impacts of climatic change, many of these activities are very important to the U.K. economy, and therefore even a small perturbation in output due to a weather extreme can have significant implications for the economy as a whole. The activities and sectors studied include energy consumption, retailing and manufacturing, construction and buildings, tourism, health, human behaviour, and fires. Both negative and positive impacts were incurred within most sectors. Net positive impacts (to the general public) were found convincingly for energy consumption and health, and clear negative impacts for buildings insurance and fires. Sectors which show clear differences in their response to winter and summer warm anomalies are energy consumption, tourism and health (greater sensitivity to winter anomalies) and buildings insurance and fires (greater sensitivity to summer anomalies). Changes in sensitivity to climate extremes may have occurred over time, and a comparison of impacts of the 1995 anomalous weather with the unusually warm dry period of 1975–1976 is approached for several series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005566710285
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  • 6
    Electronic Resource
    Electronic Resource
    National Inventories of Terrestrial Carbon Sources and Sinks: The U.K. Experience (1999)
    Springer
    Climatic change 42 (1999), S. 505-530 
    Details
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The U.K. has extensive databases on soils, land cover and historic land use change which have made it possible to construct a comprehensive inventory of the principal terrestrial sources and sinks of carbon for approximately the year 1990, using methods that are consistent with, and at least as accurate as, the revised 1996 guidelines recommended by IPCC where available – and including categories which are not currently considered under the UN Framework Convention on Climate Change. This country inventory highlights issues concerning methodology, uncertainty, double counting, the importance of soils and the relative magnitude of sources and sinks which are reported to the UNFCCC relative to other sources and sinks. The carbon sinks (negative values in MtC a-1) for categories reported to the UNFCCC, based on the IPCC categories, were estimated to be: forest trees and litter (−2.1), U.K. forest products (−0.5, ignoring imports and exports), non-forest biomass (−0.3), forest soils (−0.1) and soils on set-aside land (−0.4). The carbon sources (positive values) reported under the UNFCCC were estimated to be: losses of soil organic carbon resulting from cultivation of semi-natural land (6.2) and from urbanization (1.6), drainage of peatlands (0.3) and fenlands (0.5), and peat extraction (0.2). A range of other sources and sinks not covered by the IPCC guidelines were also quantified, namely, the accumulation of carbon in undrained peatlands (−0.7, ignoring methane emission), sediment accretion in coastal marshes (−0.1), the possible U.K. share of the CO2 and N fertilization carbon sink (−2.0) and riverine organic and particulate carbon export to the sea (1.4, which may be assumed to be a source if most of this carbon is released as CO2 in the sea). All sinks totalled −6.2 and sources 10.2, giving a net flux to the atmosphere in 1990 of 4.0 MtC a-1. Uncertainties associated with categories, mostly based on best guesses, ranged from ±15% for forest biomass and litter to ±60% for CO2 and N fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005425807434
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  • 7
    Electronic Resource
    Electronic Resource
    The tree-crop interface: representation by coupling of forest and crop process-models (1995)
    Springer
    Agroforestry systems 30 (1995), S. 199-221 
    Details
    ISSN: 1572-9680
    Keywords: agroforestry models ; crop models ; forest models ; root growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three process-based approaches to agroforestry modelling are described. These are (a) coupling a continuous-canopy forest model (Hybrid) and tropical crop model (PARCH); (b) coupling an individual-tree model (MAESTRO) with a crop model (PARCH); and (c) incorporating a combined model of evaporation and radiation interception by neighbouring species (ERIN). The coupled Hybrid/PARCH was parameterised for maize and eucalyptus, and run in five contrasting weather-types. As expected, shade is the most important factor limiting yield in wet sites; water in dry sites. Year-to-year variability in crop yield is increased by light and water competition. MAESTRO/PARCH was run with similar assumptions, and gave comparable yield predictions, except at the driest site where it allows small areas distant from the tree sufficient water to produce a modest yield. Hybrid/PARCH predicted total crop failure in the same climate. Yields on drier sites were higher in the shade, but water competition was severe close to the tree. ERIN is simpler than the above models, but is unique in including the transfer of heat and water vapour between the two canopies. Transpiration from a moist understorey can humidify air in the overstorey, and reduce its transpiration; whilst a dry understorey will give off sensible heat, which increases the vapour pressure deficit in the overstorey and causes its transpiration to increase. Changes in overstorey transpiration due to fluxes from the understorey may approach 15–20%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708921
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  • 8
    Electronic Resource
    Electronic Resource
    Optimal tree fallow rotations: some principles revealed by modelling (1995)
    Springer
    Agroforestry systems 29 (1995), S. 113-132 
    Details
    ISSN: 1572-9680
    Keywords: tree fallow ; model ; nitrogen cycle ; soil organic matter ; Acacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A model (ROTATE) of the nitrogen (N) cycle during the tree and crop phases of fallow systems [Robertson, 1994] was used to determine the primary factors influencing longterm crop yields. The model simulated the expected patterns of increase in old (recalcitrant) soil organic N during tree rotations and their decrease under continuous cropping. After 3–4 fallow cycles an equilibrium soil organic N content is reached, where N losses by crop removal are balanced by N gains by the trees (either by fixation or pumping from depth) plus small inputs in rain. The rotation period has two variable components; the cycle length (tree plus crop period) and the fraction of years in each cycle occupied by trees (1 = sole trees, 0 = sole crops). Both components have optima determined by the time taken for the trees to increase the old soil organic N pool to an optimal (but not maximal) size. This optimum exists because the rate of increase in old organic N slows as the tree fallow progresses and a time is reached (often soon after the trees reach full size) when the benefits of further improvements in soil fertility are outweighed by crop yield foregone. In the example chosen of Acacia/sorghum in the Sahel, the optimum cycle seemed to be about 50 years with half of the time in trees. The optimum fallow period is shortened by growing fast-growing trees, and the benefit of fallow periods are greatest when (i) a large proportion of the N in litter (above and belowground) is transferred to the recalcitrant soil pool, and (ii) the trees attain a large size with correspondingly large annual additions of N to the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00704881
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  • 9
    Electronic Resource
    Electronic Resource
    The central agroforestry hypothesis: the trees must acquire resources that the crop would not otherwise acquire (1996)
    Springer
    Agroforestry systems 34 (1996), S. 27-31 
    Details
    ISSN: 1572-9680
    Keywords: competition ; resource capture ; agroforestry hypotheses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simple tree-crop interaction equation is re-interpreted in terms of resource capture. Benefits in physical yields from agroforestry are to be expected only when there is complementarity of resource capture by trees and crops. Most of the current biophysical hypotheses formulated for agroforestry research are based on this central tenet, specified for various resources, soil and climatic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129630
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  • 10
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    Spatial arrangement of lateral buds at the time that they form on leaders of Picea and Larix (1978)
    Canadian Science Publishing
    Details
    Publication Date: 1978-03-01
    Description: Lateral buds were formed on Piceasitchensis (Bong.) Carr. leaders in April–May before the leaders emerged from the winter buds. At that time, the lateral buds seemed to be evenly (not randomly) dispersed over the cone-shaped surfaces of the parent leader buds. This observation was confirmed and extended by defining the positions of lateral buds on fully extended leaders of P. sitchensis, P. abies (L.) Karst., P. omorika (Pancic) Purkyne, and Larixdecidua Mill. and 'theoretically' telescoping the leaders to their probable shapes in April–May by using computer simulations. It was concluded that the centres of cell division which preceded lateral bud formation were positioned by inhibition–competition mechanisms. This explained why (a) the numbers of lateral buds were related to the sizes of the parent shoots, (b) lateral branches were dispersed with equal expectation in all compass directions, with minimal mutual shading, and (c) a variety of staggered and whorled branch arrangements could occur on leaders of different trees, as long as each whorl was associated with a branchless zone.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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