Spring Leaf Out - 2006

The photographs in the following presentation document the changes in forest trees at the margin of the pasture, adjacent to the headquarters of the Harvard Forest. These photographs were taken during spring of 2006 by John O'Keefe, and show the timing of the leaf out and leaf development this spring.

Despite the very mild and dry winter, leaf out (leaves emerged from 50% of the buds) occurred at the end of the first week in May, about two days later than the average date for the previous 16 years. This date is determined by averaging the date of leaf out of six species, including: red maple, red oak, yellow birch, white oak, striped maple and witch hazel. Due to cool, wet weather in the middle of May, leaf expansion proceeded rather slowly until the last week of May which was very warm. The images show this progression. Learn more about this study of woody species leaf phenology.