Summary
During the Hartheim Experiment (HartX) 1992 conducted in the Upper Rhine Valley, Germany, we estimated water vapor flux from the understory and the forest floor by several methods. At the vegetation “patch” level, direct estimates were made with small weighing lysimeters, and water loss was scaled-up to the stand level based on vegetation “patchtype” distribution. At the leaf level, transpiration flux was determined with a CO2/H2O porometer for the dominant understory plant species,Brachypodium pinnatum, Carex alba, andCarex flacca. Measured leaf transpiration was scaled-up to patch level with a canopy light interception and leaf gas exchange model, and then to stand level as in the case of lysimeter data, but with further consideration of patchtype leaf area index (LAI). On two days, total understory latent heat flux was estimated by eddy correlation methods below the tree canopy.
The understory vegetation was subdivided into five major patch-types which covered 62% of the ground area and resulted in a cumulative LAI of approx. 1.54 when averaged over total stand ground area and compared to the average tree canopy LAI of 2.8. The remaining 38% of ground area was unvegetated bare soil and/or covered by moss (mainly byScleropodium purum) or litter. The evapotranspiration from the understory and unvegetated areas equaled approx. 20% of total forest stand transpiration during the HartX period. The understory vegetation transpired about 0.4 mm d−1 (13%) estimated over the period of May 13 to 21, whereas evaporation from moss and soil patches amounted 0.23 mm d−1 (7.0%). On dry, sunny days, total water vapor flux below the tree canopy exceeded 0.66 mm d−1. Using the transpiration rates derived from the GAS-FLUX model together with estimates of evaporation from moss and soil areas and a modified application of the Penman-Monteith equation, the average daily maximum conductance of the understory and the forest floor was 1.7 mm s−1 as compared to 5.5 mm s−1 for the tree canopy.
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Bernhofer, Ch., Blanford, J. H., Siegwolf, R., Wedler, M., 1996: Applying single or two layer canopy models to derive conductances of a Scots pine plantation from micrometeorological measurements.Theor. Appl. Climatol. 53, 95–104.
Black, T. A., Kelliher, F. M., 1989: Processes controlling understory evapotranspiration.Phil. Trans. Roy. Soc. London, B 324, 207–231.
Caemmerer, S. von, Farquhar, G. D., 1981: Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves.Planta 153, 376–387.
Gay, L. W., Vogt, R., Bernhofer, Ch., Blanford, J. H., 1996: Flux agreement above a Scots pine plantation.Theor. Appl. Climatol. 53, 33–48.
Granier, A., Biron, P., Köstner, B., Gay, L. W., Najjar, G., 1996: Comparison of xylem sap flow and water vapor flux at the stand level and derivation of canopy conductance for Scots pine.Theor. Appl. Climatol. 53, 115–122.
Harley, P. C., Tenhunen, J. D., 1991: Modeling the photosynthetic response of C3 leaves to environmental factors. In:Modeling Crop Photosynthesis — from Biochemistry to Canopy. American society of agronomy and crop science society of America, Madison, USA. CSSA Special PublicationNo. 19, Section 2, 17–39.
Huston, M. A., 1991: Use of individual-based forest succession models to link physiological whole tree models to landscape-scale ecosystem models.Tree Physiology 9, 293–306.
Jarvis, P. G., McNaughton, K. G., 1986: Stomatal control of transpiration: Scaling up from leaf to region.Advances in Ecological Research 15, 1–49.
Joss, U., 1995: Mikrometeorologie, Profile und Flüsse von CO2, H2O, NO2, O3 in zwei mitteleuropäischen Nadelwäldern. PhD Thesis, Paul-Scherrer-Institut (PSI), Villingen, Schweiz, pp. 134.
Joss, U., Graber, W. K., 1996: Profiles and simulated exchange of H2O, O3 and NO2 between the atmosphere and the HartX Scots pine plantation.Theor. Appl. Climatol. 53, 157–172.
Kaufmann, M. R., Kelliher, F. M., 1991: Estimating tree transpiration in forest stands. In: Lassoie, J. P., Hinckley, T. M. (eds.)Techniques and Approaches in Forest Tree Ecophysiology. Boca Raton, Florida: CRC Press, pp. 117–140.
Kelliher, F. M., Hollinger, D. Y., Schulze, E.-D., Vygodskaya, N. N., Byers, J. N., Hunt, J. E., Mcseveny, T. M., 1994: Evaporation from an eastern Siberian larch forest. Proceedings of the International Symposium on Forest Hydrology, Tokyo, Japan, October 1994, pp. 123–130.
Kelliher, F. M., Whitehead, D., McAneney, K. J., Judd, M. J., 1990: Partitioning evapotranspiration into tree and understory components in two youngPinus radiata D. Don stands.Agric. Forest. Meteor. 50, 211–227.
Köstner, B., Biron, P., Siegwolf, R., Granier, A., 1996: Estimates of water vapor flux and canopy conductance of Scots pine at the tree level utilizing different xylem sap flow methods.Theor. Appl. Climatol. 53, 105–113.
Künstle, E., Mitscherlich, G., Hädrich, F., 1979: Gaswechseluntersuchungen in Kiefernbeständen im Trockengebiet der Oberrheinebene.Allgemeine Forst—und Jagdzeitung, 150. Jg. 11–12, 205–228.
Loustau, D., Cochard, H., 1991: Utilisation d'une chambre de transpiration portable pour I'estimation de I'évapotranspiration d'un sous-bois de pin maritime à molinie [Molinia coerulea., L: Moench].Ann. Sci. For 48, 29–45.
Luxmoore, R. J., King, A. W., Tharp, M. L., 1991: Approaches to scaling up pysiologically based soil-plant models in space and time.Tree Physiology 9, 281–292.
McNaughton, K. G., Jarvis, P. G., 1983: Predicting effects of vegetation changes on transpiration and evaporation. In: Kozlowski, T. T. (ed.)Water Deficits and Plant Growth, Vol. VII. New York: Academic Press, pp. 1–47.
Monsi, M., Saeki, T., 1953: Über den Lichtfaktor in den Pflanzengesellschaften und seine Bedeutung für die Stoffproduktion.Japanese Journal of Botany 14, 22–53.
Pearcy, R. W., Schulze, E. -D., Zimmermann, R., 1989: Measurement of transpiration and leaf conductance. In: Pearcy, R. W., Ehleringer, J., Mooney, H. A., Rundel, P. W., (eds.)Plant Physiological Ecology. London, New York: Chapman and Hall, pp. 137–161.
Roberts, J., Pymar, C. F., Wallace, J. S., Pitman, R. M., 1980: Seasonal changes in leaf area, stomatal conductance and transpiration from bracken below a forest canopy.Journal of Applied Ecology 17, 409–422.
Roberts, J., Wallace, J. S., Pitman, R. M., 1984: Factors affecting stomatal conductance of bracken below a forest canopy.Journal of Applied Ecology 21, 643–655.
Scholander, P. F., Hammel, H. T., Bradstreet, E. D., Hemmingsen, E. A., 1965: Sap pressure in vascular plants.Science 148, 339–346.
Schulze, E. -D., Hall, A. E., Lange, O. L., Walz, H., 1982: A portable steady state porometer for measuring the carbon dioxide and water vapor exchange of leaves under natural conditions.Oecologia 53, 141–145.
Tenhunen, J. D., Siegwolf, R. A., Oberbauer, S. F., 1994: Effects of phenology, physiology, and gradients in community composition, structure, and microclimate on Tundra ecosystem CO2 exchange. In: Schulze, E.-D., Caldwell, M. M. (eds.)Ecophysiology of Photosynthesis. Ecological Studies,100. Berlin, Heidelberg, New York: Springer, pp. 433–460.
Wedler, M., Geyer, R., Heindl, B., Hahn, S., Tenhunen, J. D., 1996: Leaf-level gas exchange and scaling-up of forest understory carbon fixation rate with a “patch-scale” canopy model.Theor. Appl. Climatol. 53, 145–156.
Whitehead, D., Hinckley, T. M., 1991: Models of water flux through forest stands: critical leaf and standparameters.Tree Physiology 9, 35–57.
Whitehead, D., Kelliher, F. M., 1991: Modeling the water balance of a smallPinus radiata catchment.Tree Physiology 9, 17–33.
Whittaker, R. H., Gilbert, L. E., Connell, J. H., 1979: Analysis of two-phase pattern in a mesquite grassland, Texas.Journal of Ecology 67, 935–952.
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Wedler, M., Heindl, B., Hahn, S. et al. Model-based estimates of water loss from “patches” of the understory mosaic of the Hartheim Scots pine plantation. Theor Appl Climatol 53, 135–144 (1996). https://doi.org/10.1007/BF00866418
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DOI: https://doi.org/10.1007/BF00866418