“Marcescence”

Tuesday March 8
I learned this word about a year ago, referring to the process whereby some deciduous trees, noticeably beech and some varieties of oak, retain their dried up leaves for much if not all of the winter, rather than losing them like the majority of deciduous trees. Around here, the beech leaves as shown in my blip provide a sole bit of colour throughout the winter days in the forest, especially when they are lit up by the sun.
Scientists have not yet established the exact reason why certain trees exhibit marcescence, however there are a few theories. Some of those theories are based on the observation that marcescent leaves are found most often on younger or smaller trees or on the lower limbs of bigger trees.
Thus, one theory suggests trees may keep their leaves to deter deer and other browsing animals from eating the nutrient-rich twigs. The leaves may conceal sumptuous new buds. Another theory relates to the availability of nutrients for trees as they head into the growing season in the spring. When leaves drop in the fall, the nutrients from those leaves that accumulate on the forest floor are pretty much gone by the next spring when the tree needs food to kick off the growing season. This mulch layer would also hold in precious moisture for the trees. If the tree holds its leaves until spring, then releases them to the ground below, they may act as quick-start nutrients as the growing season begins, and this is most important for the smaller trees under much of the canopy from larger trees.
We saw these particular beech leaves on our walk around the lake at Sharon Woods this afternoon. It was a cool day, with the sun trying to break through the clouds as we walked, but not quite succeeding.