Response of Individual Plant Actual Evapotranspiration to Canopy Closure: A Three Dimensional Model Derived from Viburnum odoratissimum

ng production and in landscapes, woody plants are initially spaced apart to develop to desirable landscape quality. As plants grow and canopies begin to interact, canopies transform from individual isolated canopies to one large, closed canopy system. Changes in individual plant actual evapotranspiration (ET A ) during the transitions between isolated and closed canopies are 30% on average. Such changes can have a substantial impact on supplemental irrigation requirements, both decreasing with closure and increasing with random removal of plants from a closed canopy. Data will be presented demonstrating changes in ET A as canopy closure progresses from isolated plants through 33%, 67%, and 100% canopy closure. Concurrent data from plants of marketable size grown in 3.8, 10.4, and 26.6 L containers were used to evaluate effects of canopy vertical thickness, and total canopy height, on the changes in ET A relative to degree of canopy closure. Contributions to ET A at 100% canopy closure and isolated plants from leaves at various depths within a canopy will be discussed.