Thresholds to Measure Urban Tree Health
Monitoring urban tree water-use enables the establishment of an upper and lower threshold for optimum water use and tree health, enabling arborists to measure tree health and make confident decisions in the irrigation management of any Urban Forest.
Tree water use is highly variable from day to day, and seasonally. If a tree begins to experience water stress it becomes more susceptible to attack from pests and disease, creating a higher risk of limbfall and insurance payout.
SFM1 Continuously Monitored The Water Use of Heritage Trees in Sydney, Australia
Near the Opera House, Sydney, Australia, a Moreton Bay Fig was installed with SFM1 Sap Flow Meters. The graph above (and right) focuses on 7 days of this tree’s water use. From hot days in April the tree water use was as much as 360 L/day and on rainy days it was as little as 44 L/day.
Over 30 days, from April 9th to May 8th the water use progressively declined by 30%. This reduction was due to reduced solar radiation and ambient temperature as early autumn transitions towards winter. The graph below demonstrates how peak water use is declining from 360 L/day to 240 L/day.