Sunday, December 24, 2006

Black pine

When our neighborhood was laid out, it seems that Black Pine was a popular tree for landscape designers. We have lines of them alternating with flowering plum trees along the white fencing at the south entrance to our subdivision. They're nice looking trees with a dark green color and a puffy appearance. Our local evergreens tend to be pointy and lighter in color, so it's a pleasant contrast. We don't shape them as is done in Japan - they just grow freely.

Sadly, the recent windstorm was not kind to the black pines. These trees completely blocked this entrance to the neighborhood. A second entrance was partially blocked. The wind blew from the south and, as one might expect, virtually all the fallen trees point to the north.

The black pines that faced the wind without an upwind deflector didn't hold. Those in north-south rows did reasonably well, but those in east-west rows fell hard. Smaller trees were more likely to survive, but the larger, more mature trees had too much sail area.

Based on the way they fell, the black pine has a shallow, broad root system. The trees that were pulled up showed roots that rarely went deeper than a foot and were typically half that. The roots were barely deeper than the sod. The breadth of the root system wasn't enough to compensate. It's not clear if the root depth is natural or is a consequence of the soil structure. The soils around here are generally poor. The glaciers scraped off most of the soil and pushed it elsehwere. When they retreated, they left sand, gravel, and clay. The builders added just enough topsoil to allow the plants to survive. But I would think that twenty years of growth would have given the trees deeper roots. The black pines are also denser than the native trees. As I look at the firs and cedars, they have a more lacy look to them. Stands of them get very dark, but individual trees are more open than the black pine. The successful trees bend with the wind and let it pass.

There will be a faction in the neighborhood that wants to replace the fallen trees with the same type. I will lobby for native trees that have shown they can withstand our blustery days.

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