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  • 1
    Electronic Resource
    Electronic Resource
    Modelling of rainfall interception loss in agroforestry systems (1991)
    Springer
    Agroforestry systems 14 (1991), S. 65-80 
    Details
    ISSN: 1572-9680
    Keywords: rainfall interception loss ; modelling ; tree spacing ; agroforestry systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two models of interception loss have been tested against new field data obtained in widely-spaced stands of Sitka spruce trees. The Gash model and a modified version of the Rutter model, have been used with data from an automatic weather station, to predict interception loss using parameters obtained from observations made in 1988 and 1989. The predictions for an eight-week period during 1987 were compared with measurements of interception loss. Good agreement between observed and predicted interception loss was obtained with both models over the whole period. The modified Rutter model gave better predictions than the Gash model for individual storm events and performed better at the wider spacings. The sensitivity of both models to the major characteristics of the tree stand structure in agroforestry systems was also investigated and it was shown that interception loss was most sensitive to boundary layer conductance and free throughfall coefficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00141597
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  • 2
    Electronic Resource
    Electronic Resource
    Management of windbreaks in the Sahel: the strategic implications of tree water use (1998)
    Springer
    Agroforestry systems 40 (1998), S. 83-96 
    Details
    ISSN: 1572-9680
    Keywords: competition ; complementarity ; groundwater ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract At sites in the Sahel where windbreaks are used to control wind erosion, management strategies are required to minimise competition for water between trees and crops. Uptake of water by windbreak trees was therefore studied in experiments designed to compare water use among tree species, assess which variables exert most control over transpiration and determine the source of water transpired by windbreak trees. Transpiration and soil-water extraction by Acacia nilotica, Acacia holosericea and Azadirachta indica trees in windbreaks were measured at the ICRISAT Sahelian Centre, Niger. Coupling of windbreaks to the atmosphere was evaluated and a stable isotope technique was used to compare utilisation of groundwater by windbreaks and crops at two sites in Niger with different water table levels. Azadirachta indica used least water, probably as a result of lower stomatal conductances, since windbreaks exhibited good physiological control over transpiration. The potential for competition for water was most severe with Acacia nilotica and Acacia holosericea, as they extracted large quantities of water through lateral roots, and at the location where trees could not access groundwater. At such sites, the effects of competition on crop productivity should be minimised by planting tree species with low water requirements and by using pruning to limit tree transpiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005962813999
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of long term CO2 enrichment on the growth, biomass partitioning and mineral nutrition of Sitka spruce [Picea sitchensis (Bong.) Carr.] (1996)
    Springer
    Trees 10 (1996), S. 393-402 
    Details
    ISSN: 0931-1890
    Keywords: Key words Elevated CO2 ; Sitka spruce ; Growth ; Allocation ; Nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings were grown for 3 years in an outside control plot or in ambient (∼355 μmol mol –  1) or elevated (ambient + 350 μmol mol –  1) atmospheric CO2 environments, within open top chambers (OTCs) at the Institute of Terrestrial Ecology, Edinburgh. Sequential harvests were carried out at the end of each growing season and throughout the 1991 growing season, five in all. Plants grown in elevated CO2 had, (i) 35 and 10% larger root/shoot ratios at the end of the first and third season, respectively, (ii) significantly higher summer leader extension relative growth rates, which declined more rapidly in early autumn than ambient grown plants, (iii) after three growing seasons a significantly increased mean annual relative growth rate, (iv) consistently lower foliar nutrient concentrations, and (v) after two growing seasons smaller total projected needle areas. Plants grown inside OTCs were taller, heavier and had a smaller root/shoot ratio than those grown outside the chambers. There was no effect of CO2 concentration on Sitka spruce leaf characteristics, although leaf area ratio, specific leaf area and leaf weight ratio all fell throughout the course of the 3 year experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185643
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of elevated CO2 concentration and nutrient supply on carbon-based plant secondary metabolites in Pinus sylvestris L. (1998)
    Springer
    Oecologia 115 (1998), S. 344-350 
    Details
    ISSN: 1432-1939
    Keywords: Key words Carbon-nutrient balance ; Elevated CO2 ; Pinus sylvestris L. ; Tannins ; Terpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated changes in carbon-based plant secondary metabolite concentrations in the needles of Pinus sylvestris saplings, in response to long-term elevation of atmospheric CO2, at two rates of nutrient supply. Experimental trees were grown for 3 years in eight open-top chambers (OTCs), four of which were maintained at ambient (∼350 μmol mol−1) and four at elevated (700 μmol mol−1) CO2 concentrations, plus four open air control plots. Within each of these treatments, plants received either high (7.0 g N m−2 year−1 added) or low (no nutrients added) rates of nutrient supply for two years. Needles from lateral branches were analysed chemically for concentrations of condensed tannins and monoterpenes. Biochemical determinations of cellulase digestibility and protein precipitating capacity of their phenolic extracts were made because of their potential of importance in ecological interactions between pine and other organisms including herbivores and decomposers. Elevated CO2 concentration caused an increase (P〈0.05) in dry mass per needle, tree height and the concentration of the monoterpene α-pinene, but there were no direct effects of CO2 concentration on any of the other chemical measurements made. High nutrient availability increased cellulase digestibility of pine needles. There was a significant negative effect of the OTCs on protein precipitating capacity of the needle extracts in comparison to the open-air controls. Results suggest that predicted changes in atmospheric CO2 concentration will be insufficient to produce large changes in the concentration of condensed tannins and monoterpenes in Scots pine. Processes which are influenced by these compounds, such as decomposition and herbivore food selection, along with their effects on ecosystem functioning, are therefore unlikely to be directly affected through changes in these secondary metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050526
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  • 5
    Electronic Resource
    Electronic Resource
    Epicuticular wax in the stomatal antechamber of sitka spruce and its effects on the diffusion of water vapour and carbon dioxide (1971)
    Springer
    Planta 98 (1971), S. 1-10 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The distribution of wax tubes on the leaf surfaces is described, especially the presence of wax tubes in the antechambers of the stomata. The extra resistances which the wax-filled antechambers add to the other resistances in the pathway for diffusion of water vapour and of carbon dioxide are calculated. We conclude that the wax-filled stomatal antechambers reduce the rate of transpiration by about two thirds but reduce the rate of photosynthesis by only about one third. Thus wax-filled stomatal antechambers are excellent antitranspirants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387018
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of long term CO2 enrichment on the growth, biomass partitioning and mineral nutrition of Sitka spruce (Picea sitchensis (Bong.) Carr.) (1996)
    Springer
    Trees 10 (1996), S. 393-402 
    Details
    ISSN: 1432-2285
    Keywords: Elevated CO2 ; Sitka spruce ; Growth ; Allocation ; Nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings were grown for 3 years in an outside control plot or in ambient (∼355 μmol mol-1) or elevated (ambient + 350 μmol mol-1) atmospheric CO2 environments, within open top chambers (OTCs) at the Institute of Terrestrial Ecology, Edinburgh. Sequential harvests were carried out at the end of each growing season and throughout the 1991 growing season, five in all. Plants grown in elevated CO2 had, (i) 35 and 10% larger root/shoot ratios at the end of the first and third season, respectively, (ii) significantly higher summer leader extension relative growth rates, which declined more rapidly in early autumn than ambient grown plants, (iii) after three growing seasons a significantly increased mean annual relative growth rate, (iv) consistently lower foliar nutrient concentrations, and (v) after two growing seasons smaller total projected needle areas. Plants grown inside OTCs were taller, heavier and had a smaller root/shoot ratio than those grown outside the chambers. There was no effect of CO2 concentration on Sitka spruce leaf characteristics, although leaf area ratio, specific leaf area and leaf weight ratio all fell throughout the course of the 3 year experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185643
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  • 7
    Electronic Resource
    Electronic Resource
    Transpiration and evaporation from heather Moorland (1984)
    Springer
    Boundary layer meteorology 28 (1984), S. 227-243 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The energy balance of an upland heath dominated by heather (Calluna vulgaris) was measured in dry and wet weather. Median values of both transpiration and evaporation rates were ca. 2 mm hr-1. The median Bowen ratio for the dry canopy was 2.0 and for the wet canopy 0.6. On dry days the median value of the saturation deficit was only 3.8 mb and that of the climatological resistance was 30 s m-1. The bulk stomatal resistance increased from ca. 50 s m -2 in the morning to over 290 s m-1 in the afternoon with an overall median value of 110 s m-1. Transpiration from the dry canopy was controlled by a combination of small saturation deficits and large stomatal resistances. The median value of the boundary-layer resistance of the canopy was 22 s m-1 and was low partly because of a large low-level drag coefficient. Saturation deficits on wet days were close to zero and evaporation of intercepted water proceeded at close to the equilibrium rate, being largely limited by the low fluxes of available energy. The water loss from heather was compared with simulated losses from coniferous forest, herbaceous crops and grassland in the same conditions to evaluate the effects of vegetation on water loss from catchments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121306
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  • 8
    Electronic Resource
    Electronic Resource
    The role of the mesophyll cell wall in leaf transpiration (1970)
    Springer
    Planta 90 (1970), S. 303-322 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Evidence is presented which suggests that the mesophyll cell walls of cotton leaves may influence observed rates of transpiration. The net diffusive flux of water vapour, from the upper and lower surfaces of a leaf, was compared with the flux of nitrous oxide through a leaf and evidence obtained of an extra resistance in the water-vapour pathway associated with water transport in the mesophyll cell walls. This extra resistance appeared to be insignificant at low transpiration rates and in turgid leaves, but increased with transpiration rate and dehydration. The most likely explanation for its origin appeared to be a reduction in hydraulic conductivity across the internal cuticle which lines the outer surfaces of the mesophyll cell walls. In turn this served to reduce the relative vapour pressure at the sites of evaporation. The experiments were conducted under conditions where stomatal opening was induced by CO2-free air. Under normal conditions stomatal closure would tend to reduce the development of this extra resistance. Even so, the results throw doubt on the validity of the long-standing assumption that the water-vapour pressure at the evaporation sites is equal to the saturation vapour pressure under all conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386383
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of elevated CO2 on sitka spruce seedlings (1993)
    Springer
    Plant ecology 104-105 (1993), S. 458-459 
    Details
    ISSN: 1573-5052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048178
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  • 10
    Electronic Resource
    Electronic Resource
    The effect of CO2 concentration on barley (1993)
    Springer
    Plant ecology 104-105 (1993), S. 462-463 
    Details
    ISSN: 1573-5052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048180
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