Spring leaf development very late this year (2005)

Thanks to one of the coolest May's on record in southern New England the green-up of our deciduous forests has progressed very slowly this spring. In addition, a significant but very patchy frost on the morning of May 13th killed the just emerging leaves of some oaks and red maples setting them even further back.

Based on observations of leaf emergence and development, also known as leaf phenology (the timing of biological events controlled by climate), made at Harvard Forest since 1990, 2005 ranks with 1992, 1997, and 2003 as a very late year for leaf emergence in most species, and may rank with 1992 as the latest year for full leaf development. Most trees in this long-term study had leaves only 1/4 to 1/3 developed at the end of May. For more information on this long-term study view this summary.