November 5, 2012

Fall a time for reading leaves

AMY IVY, Cornell Cooperative Extension

---- — Almost all the leaves have fallen, but some still linger on. 

Different species of trees turn color and drop their leaves at different times. Fall is a good time to look at broad hillsides and see what is growing where, based on when and what color the leaves turn.

The tamarack, also called larch, is a good example. During the summertime, this conifer looks like any other spruce or fir from a distance. But this native tree is the only deciduous conifer we have. Deciduous trees drop their leaves or needles in the fall, and conifers bear cones. Right now, in early November, tamaracks are bright yellow. They definitely stand out against all the evergreen conifers, including spruce, fir and pine. Soon, their needles will drop and they’ll look like dead spruces, so much so that they are often mistakenly cut down in winter.

Beeches and oaks are shade trees that hold on to their colored leaves much longer than any other. Beeches turn various shades of tan, bronze and russet and are easy to spot in the woods in the middle of winter because they are the only ones that have any leaves remaining. The leaves drop slowly throughout the winter and are often scattered over a layer of snow. They can become a bit of a nuisance on cross-country ski trails when they cause your skis to brake intermittently as you try to glide along. 

Some leaves even stay attached until just before the new leaves emerge in early spring.

There are two main groups of oaks, and the easiest way to tell them apart is by looking at their leaves. Even if the leaves have fallen, you can usually find plenty on the ground beneath the tree to help you identify them. Oak leaves contain tannins that help them resist decomposing so they remain intact for much longer than most leaves on the forest floor.

Picture an oak leaf. The most common type of oak in our region is the red oak, Quercus rubra. They cover broad hillsides and drier valleys and are a deep burgundy brown right now. The leaves have sharply pointed lobes. White oaks, Quercus alba, are less common and mostly confined to the lower elevations and valleys. These turn a gorgeous shade of red-russet and have rounded lobes. If you saw each type of leaf side by side, the difference would be obvious. 

This year seems to be a particularly good year for oak fall color. Many years, oaks turn a rather boring shade of brown with a little russet mixed in. But this year, the red tones have developed more fully, and I’ve seen some gorgeous examples on my walks and along roadsides. 

As a group, oaks have a reputation for preferring slightly acidic soil. This is especially true for the pin oak, a tree widely available in the trade, but not well-suited to some sites because of its need for low pH (acidic) soil. Both white and red oaks are more tolerant, and red oaks are also somewhat tolerant to salt. White oaks are difficult to transplant, though, and may be hard to find in the trade, so if you have some on your property, let them stay where they are. Red oaks are easier to transplant and more widely available. Pin oaks are not native but are beautiful trees and probably the most available type in the nursery. The main caution with pin oaks is that they need slightly acidic soil, with a pH less than 6.5.

Amy Ivy is executive director of Cornell Cooperative Extension, Clinton County. Office phone numbers: Clinton County, 561-7450; Essex County, 962-4810; Franklin County, 483-7403. Website: Email questions to