Premium
Surface geometry and stomatal conductance effects on evaporation from aquatic macrophytes
Author(s) -
Anderson Michael G.,
Idso Sherwood B.
Publication year - 1987
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr023i006p01037
Subject(s) - hyacinth , canopy , eichhornia crassipes , evaporation , macrophyte , stomatal conductance , aquatic plant , environmental science , canopy conductance , hydrology (agriculture) , conductance , surface water , transpiration , horticulture , botany , chemistry , ecology , environmental engineering , photosynthesis , biology , meteorology , geology , mathematics , vapour pressure deficit , geography , organic chemistry , geotechnical engineering , combinatorics
Evaporative water loss rates of several floating and emergent aquatic macrophytes were studied over a 4‐year period through comparison of daily evaporative water losses from similar‐sized vegetated ( E ) and open water ( E 0 ) surfaces. Two species with planate floating leaves (water fern and water lily) yielded E/E 0 values of 0.90 for one and four growing seasons, respectively, and displayed stomatal regulation of potential evaporation. Water hyacinths grown in ponds with different diameters exhibited E/E 0 ratios which decreased with increasing pond diameter for both short (0.06–0.36 m) and tall (0.63–0.81 m) plants, producing high linear correlations with amount of peripheral vegetative surface area. The latter relationships suggested an E/E 0 value less than unity for a relatively extensive canopy of short water hyacinths and a value of the order of 1.4 for a tall canopy possessing similar two‐dimensional surface area characteristics. The latter results were also demonstrated in a separate study utilizing polyurethane foam to insulate the peripheral exposure of tall water hyacinth canopies from advective energy. Finally, simultaneous stomatal conductance and daily E/E 0 measurements on cattail and water hyacinth canopies with identical tank diameters indicated that although the mean stomatal conductance of the peripheral exposure of the cattail canopy was 72% less than that of the water hyacinth canopy, its total evaporative water loss was nearly equivalent, due to its greater height. Reducing the surface area of the peripheral cattail exposure by the fractional amount suggested by the stomatal conductance measurements harmonized its surface geometry‐evaporation relationship with that of the water hyacinth canopy and once again demonstrated the reality of stomatal control of potential evaporation.