Wednesday, February 11, 2009

Tree Bark II

In winter you really do miss the forest for the trees. Absent the leaves I see deeper into the woods, noticing each tree and the variety of textures and colors of tree bark. The first thing that I notice is the color - brown, gray, golden, white. Texture is easier to discern if I get close, even better if I can touch the tree, feeling the bark with my fingertips (reminder: always check for spines or thorns first!).

Most trees when they start out as saplings have smooth bark. As trees age, their bark changes, much like (unfortunately) our skin. Without buds, leaves, or flowers to help identify a tree in winter, the bark offers good clues. The golden-yellow bark of the yellow birch glistens in the setting sun. The tight curls of the peeling bark can be used to start a fire even when wet. Always a great find to have yellow birch bark lying about near a campsite (peeling bark off a tree is to be avoided). The slender twigs of yellow birch have a slight wintergreen flavor. Black birch, another native species in New England, has a strong wintergreen flavor. So, taste is another clue.

The American beech. The only large woodland tree with smooth bark in this area. The pale, gray bark resembles an elephant's leg. An accidentally imported (in late 1800s to Nova Scotia) tiny scale insect has scarred many beech trees. The insect, less than 1 mm in size, carries spores of a nectria fungus that weakens the tree enough to kill it. The sap-feeding insect inserts its needle-like mouthpart into the bark, creating an opening for the nectria spores. Beech trees infected with this disease are scarred with lesions and calluses. Fortunately some beech trees seem to be resistent to the scale insect.

The well-named shagbark hickory stands out. The pale gray shaggy bark of mature trees peels into vertical strips that curve outwards. Tha large hickory nuts are a favorite of the squirrels around here. In the fall, the squirrels from high in the tree canopy drop the heavy fruits, eventually climbing down to gather up their treasure. This can be dangerous for the squirrels. Our morning walk takes us up Bald Hill Road, which is lined along one stretch with stately shagbark hickories that reach across the road. The squirrels have to be quick when they retrieve their nuts strewn across the road; sometimes they aren't quick enough. A falling hickory nut can also cause quite a jolt if it hits the top of your car or your head.

The last photo above is a bit tricky, since it is a California black oak, taken in King's Canyon National Park along the Zumwalt Meadow Trail. A lovely place. Our eastern black oak has dark ridged bark, but it is not as deeply furrowed as its California cousin.

For a beautiful photographic field guide to the buds and bark of trees from this region see Josh Sayers Portrait of the Earth.

1 comment:

  1. Great photos and I learnt something about beech bark disease! I like the winter trees as well and how one's eyes are drawn to them in the absence of foliage.

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