Flooded soils, furious winds, street construction and building destruction are a few of the onslaughts against trees. No matter the offense: trees must adapt or die. They can't pick up their roots and move to a better place. Some trees can amazingly live a couple hundred years in the same spot. They suffer the slings and arrows of outrageous people and extreme weather.
Trees do more than just get bigger as they age. Similarly we look less and less like our yearbook pictures. Tree features change throughout their lives, in the short term and long term. Some changes may at first appear to be the result of physical damage and therefore cause for alarm. Here are a few normal changes in healthy maturing trees.
In autumn white pines commonly shed their old interior needles. The interior needles change color from green to yellow. Since the needles change color and shed so quickly, it can be quite distressing for us. As long as the new needles on the ends of the branches remain green, there is no cause for alarm. Spruces and firs also lose their older needles; however, the interior older needles thin out over several years rather than a one-time fall shedding.
Arborvitaes are common evergreens with scale-like needles on flattened branchlets. In fall arborvitae will also lose the older interior branchlets which first turn brown before they drop. Again if the new growth appears fine, the shrubs are merely showing a change in seasons.
Tree bark appearance changes as the tree ages. The progression varies depending on the tree species. Analogous to our skin, young bark is smooth but then develops roughened bark with superficial cracks as the tree reaches ten to fifteen years old. I receive the most questions about changes in crabapple, maple and redbud bark. These species have smooth bark when young then as they reach their teenage years the bark changes. Crabapples develop a scaly exterior. As redbuds age their bark becomes brownish-black and flaky with glimpses of red-orange interior. The smooth bark of young red maples matures into the ridges and furrows of older maples. As long as the smooth white inner bark is not visible, changes in bark appearance is likely a normal result of aging.
Trees as they age can support whole communities of assorted life. People may notice green, plant-like masses growing on the sides of tree trunks. These are not some sort of parasite sucking the life out of the tree, but the lovely and underappreciated lichens or moss. Lichens are quite fascinating. They are actually a symbiotic union of two organisms, a fungus and a blue or blue-green alga. Only a microscope can distinguish where one ends and the other begins. The alga through photosynthesis provides carbohydrates and vitamins while the fungus obtains the necessary water and minerals. Both survive in a mutually beneficial arrangement.
The tree trunk or branch where the lichen has attached is neither hurt nor helped from the lichen. It's just the landing pad. Lichen can be quite beautiful and varied. I call it "tree bling". Some lichens may be flat or look leafy similar to kale and may be red, green or blue-green. Fluffy moss also hangs out on tree trunks. This is the perfect time of year to enjoy and appreciate the stunning beauty and tenacity of trees.
Join a bunch of tree lovers in the Master Gardener program. Training in Champaign, Ford, Iroquois and Vermilion counties starts the end of January 2015 in three locations; Champaign, Danville and Onarga; however, applications are due November 28, 2014. Check out our web site for more information and to apply online http://web.extension.illinois.edu/cfiv/ Questions? Champaign office (217.333.7672); Danville (217.442.8615); or Onarga (815.268.4051).