Abstract
A multilayer canopy model of a pine forest is used to investigate the sensitivity of the water balance of the wet canopy to variations in meteorological input. The multilayer model does not take into account large-scale eddies, which are now considered to be of importance to canopy transport. It does, however, provide realistic simulations of wet canopy water balance and often predicts interception loss rates higher than those predicted by a unilayer model for the same meteorological input. Stable layers both within and above the canopy are often simulated during rainfall events, and these may help to spontaneously generate large-scale eddies or waves within forest canopies. The sensitivity study for a wet canopy suggests that low vapour pressure deficits and low wind speeds are associated with unstable surface conditions, and increasing values of both variables are associated with decreasing canopy drainage values and increasing evaporative losses. Low short- or long-wave radiation inputs are associated with stable surface conditions, and increasing values of both variables are associated with decreasing canopy drainage values and increasing evaporative losses. Increasing temperature is associated with increasing surface stability and increasing canopy drainage and decreasing evaporative losses. In real situations the tendency for increasing temperature to cause surface stability and decreased evaporative loss is probably compensated by the opposite effects of increasing short- or long-wave radiation. The model simulations suggest that wet forest canopies may be better ventilated at low temperatures, if other meteorological conditions are constant.
Similar content being viewed by others
Abbreviations
- D :
-
Drainage of intercepted water I (mm)
- E :
-
Evapotranspiration per rainfall cycle (mm)
- E I :
-
Evaporation of intercepted water I (mm)
- E S :
-
Soil evaporation (mm)
- E T :
-
Bulk canopy transpiration (mm)
- λE :
-
Latent heat flux (W/m2)
- λE A :
-
Adiabatic component of latent heat flux (1 - Ω) λE x(W/m2)
- λE D :
-
Diabatic component of latent heat flux ΩλE Q(W/m2)
- λE q :
-
‘Equilibrium’ latent heat flux ΩλE Q (W/m2)
- λE X :
-
‘Exchange’ latent heat flux ϱc PδeR/γrS(W/m2)
- H :
-
Sensible heat flux (W/m2)
- I :
-
Interception of water by canopy (mm)
- K :
-
Extinction coefficient of radiation, eddy diffusivity
- L :
-
Leaf area index
- P :
-
Rainfall intensity (mm/h)
- P + :
-
Mean rainfall rate during cycle (mm/h)
- Q A :
-
Available energy at effective evaporating surface (W/m2)
- Q L :
-
Incident long-wave radiation at canopy surface (W/m2)
- Q L + :
-
Net long-wave radiation at effective surface (W/m2)
- Q S :
-
Incident short-wave radiation at canopy surface (W/m2)
- Ri :
-
Richardson number
- S T :
-
Total storage of water on canopy (mm)
- S U :
-
Excess storage of water on canopy contributing to drainage (Rutter et al., 1971) (mm)
- C P :
-
Specific heat capacity of air at constant pressure (J/kg °C)
- δe R :
-
Potential vapour pressure deficit at z R(mb)
- k :
-
Von Karman's constant
- r A :
-
Bulk aerodynamic resistance to transfer of water vapour between canopy and z R(s/m)
- r S :
-
Bulk canopy stomatal resistance (s/m)
- s :
-
Slope of curve of saturation vapour pressure versus temperature at mean air temperature (mb/°C)
- u R :
-
Wind speed at z R(m/s)
- z R :
-
Reference level in ‘mixed layer’ (100 m)
- z 0 :
-
Canopy roughness length (m)
- α :
-
Canopy albedo
- γ :
-
Psychrometric constant (mb/°C)
- ɛ :
-
Long wave emissivity of canopy
- ε:
-
Potential temperature at z R(°C)
- λ :
-
Latent heat of vapourisation of water (J/kg)
- η :
-
Loss ratio E/P + (%)
- μ :
-
Sine of angle of sun above horizon
- ϱ :
-
Air density (kg/m3)
- Ω:
-
Uncoupling coefficient 1/(1 + (γ/(s + γ))(r s /r A ))
- W :
-
Referring to wetting phase of rainfall cycle
- D :
-
Referring to drying phase of rainfall cycle
References
Allen, L. H.: 1968, ‘Turbulence and Wind Speed Spectra within a Japanese Larch Plantation’, J. Appl. Meteorol. 7, 73–79.
Bache, D. H.: 1986, ‘Momentum Transfer to Plant Canopies: Influence of Structure and Variable Drag’, Atmos. Envir. 20, 1369–1378.
Baldocchi, D. D. and Hutchison, B. A.: 1987, ‘Turbulence in an Almond Orchard: Vertical Variations in Turbulent Statistics’, Boundary-Layer Meteor. 40, 127–146.
Beven, K. J. and Kirkby, M. J.: 1978, ‘A Physically Based, Variable Contributing Area Model of Basin Hydrology’, Hydrol. Sci. Bull. 24, 43–69.
Calder, I. R.: 1985, ‘What Are the Limits on Forest Evaporation? - Comment’, J. Hydrol. 82, 179–192.
Calder, I. R.: 1986, ‘What Are the Limits on Forest Evaporation? - A Further Comment’, J. Hydrol. 89, 33–36.
Calder, I. R.: 1990, Evaporation in the Uplands, Wiley, Chichester.
Calder, I. R. and Wright, I. R.: 1986, ‘Gamma Ray Attenuation Studies of Interception from Sitka Spruce: Some Evidence for an Additional Transport Mechanism’, Water Resour. Res. 20, 409–17.
Cooper, T. A. and Lockwood, J. G.: 1987, ‘Numerical Simulation of the Water Balance of a Multilayer Pine Canopy and the Influence of Rainfall Distribution’, Water Resour. Res. 23, 1645–1656.
Corrsin, S.: 1974, ‘Limitations of Gradient Transport Models in Random Walks and Turbulence’, Adv. Geophys. 18A, 25–60.
Crowther, J. M. and Hutchings, N. J.: 1985, ‘Correlated Vertical Wind Speeds in a Spruce Canopy’, in B. A. Hutchison and B. B. Hicks (eds.), Forest-Atmosphere Interactions, Reidel, Dordrecht, pp. 543–561.
Denmead, O. T.: 1984, ‘Plant Physiological Methods for Studying Evapotranspiration: Problems of Telling the Forest from the Trees’, Agricultural Water Management 8, 167–189.
Denmead, O. T and Bradley, E. F.: 1985, ‘Flux Gradient Relationships in a Forest Canopy’, in B. A. Hutchison and B. B. Hicks (eds.), Forest-Atmosphere Interactions, Reidel, Dordrecht, pp. 421–442.
Feigelson, E. M.: 1984, Radiation in a Cloudy Atmosphere, Dordrecht, Reidel.
Finnigan, J. J.: 1979, ‘Turbulence in Waving Wheat II. Structure of Momentum Transfer’, Boundary-Layer Meteor. 16, 213–236.
Finnigan, J. J.: 1985, ‘Turbulent Transport in Flexible Plant Canopies’, in B. A. Hutchison and B. B. Hicks (eds.), Forest-Atmosphere Interactions, Reidel, Dordrecht, pp. 443–480.
Finnigan, J. J. and Raupach, M. R.: 1987, ‘Transfer Processes in Plant Canopies in Relation to Stomatal Characteristics’, in E. Zeizer, G. Farquhar, and I. Cowan (eds.), Stomatal Function, Stanford University Press, Stanford, pp. 385–429.
Goudriaan, J.: 1977, ‘Crop Micrometeorology: A Simulation Study’, PUDOC, Wageningen Centre for Agricultural Publishing and Documentation, Netherlands.
Hancock, N. H., Sellers, P. J., and Crowther, J. M.: 1983, ‘Evaporation from a Partially Wet Forest Canopy’, Ann. Geophys. 1, 139–146.
Hutchison, B. A. and Hicks, B. B.: 1985, Forest-Atmosphere Interactions, Reidel, Dordrecht.
Jarvis, P. G.: 1976, ‘The Interpretation of the Variations in Leaf Water Potential and Stomatal Conductance Found in Canopies in the Field’, Phil. Trans. R. Soc. Lond. Ser. B. 273, 593–610.
Jarvis, P. G., James, G. B., and Landsberg, J. J.: 1976, ‘Coniferous Forest’, in J. L. Monteith (ed.), Vegetation and the Atmosphere, vol. 2, Academic Press, New York, pp. 171–240.
Kasanaga, H. and Monsi, M.: 1954, ‘On the Light Transmission of Leaves, and its Meaning for the Production of Matter in Plant Communities’, Jap. J. Bot. 14, 304–324.
Lockwood, J. G.: 1990, ‘The Influence of Temperature Variations on Interception Loss and Water Storage in Vegetation Canopies’, Water Resources Research 26, 941–943.
McNaughton, K. G. and Jarvis, P. G.: 1983, ‘Predicting Effects of Vegetation Changes on Transpiration and Evaporation’, in T. T. Kozlowski (ed.), Water Deficits and Plant Growth, vol. 7, Academic Press, New York, pp. 1–47.
McNaughton, K. G. and Spriggs, T. W: 1986, ‘A Mixed-Layer Model for Regional Evaporation’, Boundary-Layer Meteor. 34, 243–262.
Meehl, G. A. and Washington, W. M.: 1988, ‘A Comparison of Soil-Moisture in Two Global Climate Models’, J. Atmos. Sci. 45, 1476–1492.
Mitchell, J. F. B., Wilson, C. A., and Cunnington, W. M.: 1987, ‘On CO2 Climate Sensitivity and Model Dependence of Results’, Quart. J. R. Met. Soc. 113, 293–322.
Monsi, M. and Saeki, T.: 1953, ‘Ueber den Lichtfaktor in den Pflanzengesellschaft und seine Bedeutung fur die Stoffproduktion’, Jap. J. Bot. 14, 22–52.
Monteith, J. L. and Unsworth, M. H.: 1990, Principles of Environmental Physics, Edward Arnold, London.
Morton, F. I.: 1984, ‘What Are the Limits on Forest Evaporation?’, J. Hydrol. 74, 373–398.
Morton, F. I.: 1985, ‘What Are the Limits on Forest Evaporation? - Reply’, J. Hydrol. 82, 184–192.
Oliver, H. R.: 1971, ‘Wind Profiles in and above a Forest Canopy’, Quart J. R. Met. Soc. 97, 548–553.
Oliver, H. R.: 1975, ‘Ventilation in a Forest’, Agric. Met. 14, 347–355.
Paulson, C. A.: 1970, ‘Mathematical Representation of Wind Speed and Temperature Profiles in the Unstable Atmospheric Surface Layer’, J. Appl. Met. 9, 857–861.
Priestley, C. H. B. and Taylor, R. J.: 1972, ‘On the Assessment of Surface Heat Flux and Evaporation Using Large-Scale Parameters’, Mon. Wea. Rev. 100, 81–92.
Raupach, M. R.: 1989, ‘Stand Overstorey Processes’, Phil. Trans. R. Soc. Lond. B 324, 175–190.
Raupach, M. R., Coppin, P. A., and Legg, B. J.: 1986, ‘Experiments on Scalar Dispersion within a Model Plant Canopy. Part 1: The Turbulent Structure’, Boundary-Layer Meteor. 35, 21–52.
Raupach, M. R. and Thom, D. S.: 1981, ‘Turbulence in and above Plant Canopies’, Ann. Rev. Fluid Mech. 13, 97–129.
Rind, D.: 1988, ‘The Doubled CO2 Climate and the Sensitivity of the Modelled Hydrologic Cycle’, J. Geophys. Res. 93, 5385–5412.
Rutter, A. J., Kershaw, K. A., Robins, P. C., and Morton, A. J.: 1971, ‘A Predictive Model of Rainfall Interception in Forests. I. Derivation of the Model from Observations in a Plantation of Corsican Pine’, Agric. Meteorol. 9, 367–384.
Scorer, R. S.: 1978, Environmental Aerodynamics, Ellis Horwood, Chichester.
Sellers, P. J.: 1981, ‘Vegetation Type and Catchment Water Balance: a Simulation Study’, PhD thesis, School of Geography, University of Leeds, UK.
Sellers, P. J. and Lockwood, J. G.: 1981a, ‘A Computer Simulation of the Effects of Differing Crop Types on the Water Balance of Small Catchments over Long Time Periods’, Quart. J. R. Met. Soc. 107, 395–414.
Sellers, P. J. and Lockwood, J. G.: 1981b, ‘A Numerical Simulation of the Effects of Changing Vegetation Type on Surface Hydro-Climatology’, Climatic Change 3, 121–136.
Sellers, P. J. and Lockwood, J. G.: 1982, ‘A Computer Simulation of the Effects of Differing Crop Types on the Water Balance of Small Catchments over Long Time Periods’, reply to comment by Shuttleworth and Gash, Quart, J. R. Met. Soc. 108, 467–470.
Shuttleworth, W. J. and Calder, I. R.: 1979, ‘Has the Priestley-Taylor Equation Any Relevance to Forest Evaporation?’, J. Appl. Meteor. 18, 639–646.
Soer, G. J. R.: 1977, The Tergra Model - a Mathematical Model for the Simulation of the Daily Behaviour of Crop Surface Temperature and Actual Evapotranspiration, Institut voor Culturtechnik en Waterhuishouding, Wageningen, Netherlands, Nota 1014.
Stewart, J. B.: 1971, ‘The Albedo of a Pine Forest’, Quart. J. R. Met. Soc. 97, 561–564.
Tajchman, S. J.: 1972, ‘The Radiation and Energy Balances of Coniferous and Deciduous Forests’, J. Appl. Ecol. 9, 357–359.
Thom, A. S.: 1971, ‘Momentum Absorption by Vegetation’, Quart. J. R. Met. Soc. 97, 414–428.
Thom, A. S., Stewart, J. B., Oliver, H. R., and Gash, J. H. C.: 1975, ‘Comparison of Aerodynamic and Energy Budget Estimates of Fluxes over a Pine Forest’, Quart. J. R. Met. Soc. 101, 93–105.
Unsworth, M. H. and Monteith, J. L.: 1975, ‘Geometry of Long-Wave Radiation at the Ground. I. Angular Distribution of Incoming Radiation’, Quart. J. R. Met. Soc. 101, 13–24.
Wilson, N. R. and Shaw, R. H.: 1977, ‘A Higher-Order Closure Model for Canopy Flow’, J. Appl. Meteor. 16, 1197–1205.
Waggoner, P. E. and Reifsnyder, W. E.: 1968, ‘Simulation of Temperature, Humidity, and Evaporation Profiles in a Leaf Canopy’, J. Appl. Meteor. 1, 400–409.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lockwood, J.G. The sensitivity of the water balance of a wet multilayer model pine canopy to variations in meteorological input. Climatic Change 20, 23–56 (1992). https://doi.org/10.1007/BF00144107
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00144107