Leaf duration and the sequence of leaf development and abscission in northeastern urban hardwood trees

Urban trees provide both physical and esthetic benefits that are often related to the presence or absence of leaves. Periods of leaf development and leaf abscission and the duration of the leaf season were determined for twelve common urban tree species. Apple, Norway maple, and grey birch developed leaves earlier than other species. Green ash tended to lose leaves earlier than other species. Actual dates were not considered important, because of weather differences between years, but the order of phenologic stages should be similar each year. The average time during which crowns were 50% or more of full density ranged from 154 days for green ash to 192 days for apple. Most species that developed leaves early tended to retain them longer and to have long leaf durations. Green ash lost leaves first and had the shortest leaf season.