Quercus engelmanii | Arcadia
When evaluating any tree for urban use, a key consideration is the way the tree roots intereract with existing urban pavement. To explore this question, existing urban Engelman Oaks were sought out in Pasadena and Arcadia, two locations know to harbor, and even embrace, the Engelman Oak, as both cities were built into large existing native stands of Engelman Oak. Soils in these cities are of a deep, alluvial nature, ideal for deeply-rooted, ground-water-seeking oak trees. Such soils promote and abet deep rooting, making the stable relationship seen here possible. Were soils thinner, the possibility of pavement disruption become much higher, tree size is much reduced, and drought tolerance - mediated by access to groundwater - will be vastly reduced.