No Place For Idleness

Day 363: The Pacific Northwest is no place for idleness. Hold still too long, and you'll colonize with lichens and moss. Here, an Usnea and a Parmelia have found a home on the Barberry (Berberis), a shrub not particularly recognized as ideal lichen habitat. In fact, the Parmelia has probably anchored itself in the thin film of dust/dirt adhering to the thin bark. The same species has attached itself to the vinyl siding on my house and the metal gate of the Berry Pen. It's one very determined lichen! Usneas tend to be a little more selective, but we have quite a wide variety of them here, and I have observed them on many of our native and non-native trees. A notable exception is cedar, but although cedar is relatively resistant to lichens, there are still a few which grow on it.

Lichenized!

Day 143: Contrary to popular belief, most lichens do not damage the trees on which they live. The fact is, trees under stress from disease or climatological influences are more likely to provide physical niches in which lichens may grow. Organic material and dust particles collect in the cracks of damaged bark, and over time, become the medium in which lichens may take hold. The association between dying trees and the presence of lichens is clear, but the relationship is often misinterpreted. The lichens are misconstrued as the cause of the tree's declining health instead of being a symptom of it. Why, then, do some types of lichen grow on one type of tree and not on another? Lichens' preferences for certain types of tree are due to a number of different factors: acidity, persistence of light/shade, bark porosity, etc. When the species' requirements are met in the proper combination, lichenization will occur.