Water Loss Estimates of Three Containerized Landscape Tree Species Using Thermal Dissipation Probes and Load Cells

Abstract

Granier style thermal dissipation probes (TDP) have been used to estimate whole plant water loss on a variety of tree and vine species. However, studies using TDPs to investigate water loss of landscape tree species is rare. This research compared containerized tree water loss estimates of three landscape tree species using TDPs with containerized tree water loss estimates as measured by load cells. Over a three-year period, established, 5.0 cm caliper Bradford pear (Pyrus calleryana `Bradford'), English oak (Quercus robar), and sweetgum (Liquidambar styraciflua `Rotundiloba') trees in 75 L containers were placed on load cells, and water loss was measured for a 60-d period. One 3.0 cm TDP was placed into the north side of each trunk 30 cm above soil level. To reduce evaporation, container growing media was covered with plastic. Each night, plants were irrigated to soil field capacity and allowed to drain. To provide thermal insulation TDPs and tree trunks (up to 30 cm) were covered with aluminum foil coated bubble wrap. Hourly TDP water loss estimates for each species over a three-day period indicate TDP estimated water loss followed a similar trend as load cell estimated water loss. However, TDP estimates were generally less, especially during peak transpiration periods. In addition, mean, total daily water loss estimates for each species was less for TDP estimated water loss when compared to load cell estimated water loss. Although TDP estimated water loss has been verified for several plant species, these data suggest potential errors can arise when using TDPs to estimate water loss of select landscape tree species. Additional work is likely needed to confirm estimated sap flow using TDPs for many tree species.