The lustrous sheen of yellow birch bark adds a warm element to Vermont woods, even on a gray, rainy day. Yellow birch does not occur in pure stands, but it does appear in all stages of forest succession.
Though it is a significant component of the northern hardwood forest, yellow birch will also be found in the cool moist places where hemlock thrives or even among spruce and fir in cold damp pockets. Moist would be its middle name, if plants had middle names. Perhaps it is found in these wet hollows because few other trees grow well there. In the southern part of its range, it requires mountainous mists, but all of Vermont has places that are adequately soggy.
Without moisture, yellow birch seedlings will not survive. They will wither and die when the forest litter dries out in summer. It seeds in well after fires which destroy the litter, but if bare soil is not available, damp mossy logs and stumps are pay dirt for yellow birch seedlings. Think back and you will remember seeing a yellow birch tree standing on mangrovelike stilts. This results from the young tree's roots reaching out and down its nursery log; years later, when the log has rotted back to soil, the birch stands high on its strong thickened roots.
One of the organisms that moves in on weakened or injured yellow birch trees is easy to identify. The fungus Inonotus obliquus forms hard, irregular, coal-black masses of fungal tissue which erupt from columns of internal decay to form what are called sterile conks. This fungus does not produce spores until three or four years after the tree has died.
Overall, yellow birch health in Vermont is "fair," according to forest health specialists. The dry summer and snowless winter way back in 1980-81 stressed the species and may account for the fairly large number of standing dead trees which are now present.
Yellow birch leaves are similar to those of paper birch, but are bigger, with sharp doubly serrate margins. The branches grow upwards. The bronzy curls of its bark give way to rough plates when the trees are larger than about 12 inches in diameter. If you chew on a twig, a slight taste of wintergreen will confirm your identification.
Male catkins are formed in late summer and they dangle from the twigs all winter. The female flowers are also formed in late summer, but they stay hidden within buds until spring. The fruits ripen b late August or early September, but are shed over a long period. They travel best when blown across crusted snow.
Red polls and pine siskins eat the seeds, grouse eat the catkins, and moose and hare browse the twigs.
Yellow birch is highly preferred for veneer, the thin skinlike coverings used on doors and cabinets. To make veneer, logs are turned on a lathe against a knife edge. Yellow birch peels off the knives well as it is even in grain and density. Maybe mother nature had a lathe in mind when she designed yellow birch because the trees are also quite round, have very little taper, and grow to a considerable height before branching. About 40% of the sawlogs harvested in Vermont get turned into veneer.