Even the air sends me reeling with the scent of moist soil mingling with the odor of green plants and grasses. Life around us lately trills and tangles; it’s hard to finish a conversation without being distracted by a desparate bird seeking his ideal mate to fill that castle of a nest he just finished.
Lichen on a shortleaf pine.
Does the presence of lichen on our pines suggest that our air is as fresh as we hope? The University of Delaware Cooperative Extension gives the low-down on lichens and what lichens might indicate about the health of a tree:
Lichens often appear as a perennial green or gray coating on the trunks and branches of trees. They are actually two organisms in one, being composed of a fungal body harboring green or blue-green algae, which live together in complete harmony. In the symbiotic relationship, the algae, through photosynthesis, supply carbohydrate food to the fungus and, in turn, receive protection and trapped water and mineral elements from the fungus. In this relationship, the algae and the fungus are not distinguishable except with a microscope, and the lichen persists longer than the alga or the fungus would separately.
Lichens do not parasitize trees, but merely use the bark as a medium on which to grow. In fact, lichens can be seen growing on rocks, weathered lumber, or on dead branches fallen from the tree. Some may consider lichens unsightly, but they are not generally injurious except that, when extensive, they may interfere with the gaseous exchange of the parts they cover. Because of their extreme sensitivity to sulfur dioxide air pollution, lichens seldom appear on trees in industrial cities… They rarely develop on rapidly growing trees, because new bark is constantly being formed before the lichens have an opportunity to grow over much of the surface. Because of this, lichens on certain species may indicate poor tree growth. We have noticed that in some plantings, those trees that are more vigorous have fewer lichens than those of the same age nearby in a state of decline. Few studies have been conducted to verify any correlation between lichen growth and tree vigor.
Increases in lichens are sometimes associated with moist climate – perhaps the relatively moist weather of the past two summers accounts for increases in lichen questions. Lichens proliferate when more light is provided, which could explain why they are more frequently seen on dead, leafless branches.
So we’ll keep our lichen friends, and do a survey of lichen-laden trees and trunk size. Maybe we’ll also make a map of trees with lichen to use next year in a comparative moisture study. If lichens increase- or develop on new trees- before next year, what will this mean, if anything, about change in annual moisture levels or climate change, more generally?
Torrential morning thunderstorms beat the ground, and then make way for sunshine and gargantuan puddles in the afternoon.
Baby toes curling over clover and grass so soft that shoes seem superfluous. The barefoot season has officially begun.
Old books about rocks and geology picked up for a pittance at yard sales- the beginning of new stories. And questions.