Water Resources Research Act Program

Details for Project ID 2016NV214B

Assessing Tree to Grass Water Use Ratios; Significance to Urban Water Conservation

Institute: Nevada
Year Established: 2016 Start Date: 2016-03-01 End Date: 2018-02-28
Total Federal Funds: $21,000 Total Non-Federal Funds: $43,121

Principal Investigators: Dale Devitt

Abstract: We are seeking funds to support a newly funded project by the United States Golf Association which will start in January 2016. Communities throughout the arid west are faced with the challenge of meeting water demands with fixed water resources under an extended hydrologic drought. Water conservation programs are being implemented to help save water in the urban setting. Turfgrass can use significant amounts of water, but landscape trees can also use significant amounts of water. We wish to quantify tree to grass water use rates to demonstrate the tradeoffs that exist between these two landscape covers. A scientific approach is needed that recognizes that long term water savings with xeric landscapes can disappear as trees become larger over time. With greater scientific information, landscape architects, golfcourse and park superintendents, homeowners, horticulturalists and water managers can design/recommend tree grass combinations that provide aesthetically pleasing landscapes while saving significant amounts of water. We would address five scientific questions; 1) What are the water use rates of mature landscape trees growing in an arid environment? 2) What are the water use rates of these trees relative to morphological parameters that will allow such data to be scaled to other locations? 3) What are the water use trade-offs between tree species and turfgrass on an area basis? 4) Will the tree to grass water use ratios estimated for mature trees capture the projected values based on smaller trees published by Devitt et al. (1995)? and 5) How do the tree water use rates, under experimental conditions, compare with water use rates under field conditions and what is the spatial impact of tree water use on turfgrass? The research will be conducted in a plot of landscape trees that were planted at the Center for Urban Horticulture and Water Conservation in 1998 and represent mature size trees. There are 10 different species representing the more common species planted in the arid southwest. Hydrologic balances will be closed on the water basins of the selected trees. Transpiration at the whole tree level will be assessed on each of the trees with Granier probes to assess transpiration velocity. The velocity measurements will then be weighted with the area of xylem conductive tissue assessed with dye. Turfgrass water use will be estimated on four different species with non-weighing lysimeters, providing the generation of 40 different tree grass water use ratios on a monthly and yearly basis. This research will support a female graduate student in the School of Life Sciences and three minority undergraduate students and would culminate in the publication of a peer reviewed manuscript and the distribution of an informational fact sheet to individuals involved in the management, regulation and design of urban landscapes.