Specification of Soil Volume and Irrigation Frequency for Urban Trees

Abstract

Typically, limitations in soil volume deprive urban trees of adequate water supplies. As a result, tree survival, health, and development can be adversely affected. Proper sizing of urban tree pits and containers can mitigate these unfavorable consequences. Current climate-based recommendations of appropriate soil volumes for urban trees are based on average conditions and therefore do not address daily and annual variations in weather. Here, a methodology based on daily weather observations is presented and implemented. The method allows return periods to be assigned to harmful water stress events based on container volume and, separately, on irrigation interval. For example, in New York City, without irrigation a medium-size tree grown in 17.0 m