There are so many times here in Shenyang that I get hit in the face with my own ignorance. I really don't know anything about China in general, Shenyang, my school, or even the woman emptying the trash baskets in my classroom in particular, and I want to know more.
On a trip to town in the van I turned to George, one of our students, and asked, “Why are the tree trunks painted white for about a meter from the ground up?” With his limited English (still light years ahead of my microscopic Chinese) George said that the paint protects the trees' heart from the cold. This answer dovetailed nicely with my observations that the painting had been taking place more since the onset of winter had progressed. I wasn't sure though.
You see I had noticed in Nicaragua that people there also painted the lower parts of trees white. There it wasn't quite as prevalent, but it occurred nonetheless. When I asked Nicaraguan friends about the tree painting I was told that the white paint helped protect the trees from insect infestation. According to them bugs that might crawl up the trunks to devour the trees' uppers were more visible, and therefore vulnerable, to predators as they crossed the no-man's land of whiteness.
All this came to a head recently as I left school and walked to my apartment. For some reason at that moment the sight of all the saplings with their spindly bodies coated part-way up with bright white paint caught my attention, imagination, and curiosity. I decided to do some research (and take some pictures and make this the topic of my blog.)
A quick on-line search turned up that I was not the first person to wonder about white paint on trees. It also turned up a solid baker's dozen reasons why, any one of which could be true and perhaps all are. The lack of consensus, though, fueled my suspicions that perhaps people painted trees out of habit and then rationalized it in different ways.
Of the strongest contenders in the why-paint-tree-trunks-white explanations several emerged as more persuasive reasons. A professor from Montana State University argued very convincingly that the climates in certain northern zones can get very cold while at the same time have days of plentiful brigh sunshine. According to her the sunlight tricks the young trees (those with less bark separating their living layer, the cambium, from the outside world) into thinking that spring has arrived and they begin to grow. When the sun sets and the frigid cold sets in, those no-longer dormant trees can't handle it and suffer damage which can include scars on the bark caused by the sap freezing and expanding. Those scars, since caused by the sunlight, are called “sun scald” and can become entry points for insect infestation (shades of Nicaragua). The white paint serves to reflect the day's sunlight, preventing it from significantly warming the thin trees.
Shenyang is certainly in the freeze-your-patootie zone on the globe. And we get plenty of bright sunlight during most days. This could be the reason why locals paint their trees. It's also true that it's mostly small trees that win a theoretically protective coating. I do wonder why one meter seems to be the magic amount of coverage that the trees need. I was even more taken by the reflection concept.
You see some other sources on the web had claimed that the trees were painted white mainly because the white paint would reflect light at night and thus serve to demarcate the line between road and off-road. It is true that painting tree trunks white is much more common along roadways than elsewhere. Also, there aren't roadside reflectors here in China to keep drivers informed of the road's edge. This claim had a certain common-sense appeal, but it didn't seem comprehensive enough.
Even less comprehensive, but more backed by linguistic evidence, was one source's explanation that the practice came from French orchards where it even had a specific name. “Lait de chaux” translates as milk of lime and that's because the paint used was whitewash which is traditionally made from lime. According to this theory, the lime serves as a natural insecticide and thus protects the trees from crawling insects that might otherwise travel from the ground up the trunks to devastate the trees' foliage. This again fit nicely with what I'd heard in Nicaragua, but had a few weevil-like holes. Why didn't the orchardists worry about flying insect damage? Why do Chinese people paint non-fruit trees white? (and why wouldn't it be used other trees in France? Wouldn't French gardeners want to protect their non-fruit trees from those same creepy-crawlies?)
One of the most pragmatic theories was that the practice came from frugal somebody some where who didn't want to simply throw away the excess paint he or she had after painting a house or building or fence. According to this theory, the surplus went on the nearby trees (and in some cases rocks, pathways, etc.) and was so eye-catching that the practice spread.
I don't know to believe. All or none of these theories could be the reason why Chinese trees carry their white badges. Since I can't speak enough Chinese to ask anyone why they paint their trees (and there's no telling that the person wielding the paintbrush will actually know the reason behind their artistry). As with so many things I'll have to be satisfied with keeping my ears and mind open to what explanations I may encounter. (Especially now that I've also seen trees with their trunks wrapped with twine.)
Meanwhile I'll repeat, over and over: “I don't know anything; I want to know more.”
