This morning Image Tree Service began a process to remove trees throughout the City's park system and in the downtown area that have died due to the ongoing drought. This death, often called drought-related tree mortality, is caused by trees becoming too dependent on turf or surface irrigation water instead of developing deep root structures.

Even though we applied recycled water to trees that were subject to drought stress, each tree’s ecosystem ultimately determined its fate. The photos below show a row of trees in Barbieri Park that had similar amounts of recycled water applied to each root system, yet one died while the others survived.  

While drought-related tree mortality can affect most tree species, Coast Redwoods are highly susceptible due the amount of water these trees need to survive. The Coast Redwood pictured below was a signature tree in Gibbs Park for decades. During the latter years, we found that this tree’s root structure extended far out into the park area, and we estimate that the tree consumed up approximately 2,000 gallons of water per day.

Irrigation practices have changed significantly since many of these trees were planted. Today, new trees that are planted correctly have “deep root” or “direct to root” irrigation systems that deliver needed water to roots below the surface. In addition to helping to develop trees that can sustain drought conditions, these systems save water that would otherwise be lost to evaporation.

For more information on the effects of drought on trees, please visit   https://www.fs.usda.gov/psw/topics/tree_mortality/california/index.shtml.