Bigger Roots, Stronger Cities: Rethinking Tree Watering for Climate Resilience

I propose presenting a slightly modified version of the session from the ISA Annual Conference 2024 in Atlanta. Lynsey Nielson and I discussed the impact of watering established trees. A major issue is shallow rooting and limited root systems due to irrigation, leading to instability and reduced drought resilience. Newly planted trees under automatic irrigation face similar problems. Yet, few seriously examine how irrigation methods impact tree stability and long-term health. As drought spreads, those in newly affected areas look to regions with longer experience for guidance. If these regions have adopted poor watering practices, mistakes may be repeated, leading to further tree loss. It’s time to open this discussion and take a proactive approach. Research confirms that retaining and improving the health of established trees provides significantly more ecosystem services than planting new ones. Yet, with increasing drought, heat waves, and irregular precipitation, large trees are suffering. Water is becoming an ever-scarcer resource, and irrigation practices often fail to support tree health while wasting water. In many cases, irrigation itself puts trees at risk. How can arborists balance resource conservation with effective care for these trees? In 2020, Salt Lake City lost thousands of trees in a single windstorm. Arborists identified poor watering practices, particularly shallow irrigation, as a key factor in tree failure. Using this example, I will explore the consequences of past water management strategies, their effects on mature trees, and solutions based on tree biology to improve resilience and conserve water. This presentation aims to highlight a critical gap in holistic tree management, emphasizing the role of proper watering in climate change adaptation. By optimizing irrigation, we can not only sustain urban forests but also leverage trees for microclimate cooling, maximizing their ecosystem services in an era of climate emergency.