The State of the Urban Forest
To make way for growing urbanization, our forests were clear-cut in the late 1800’s. Street trees were planted and by the turn of the century, almost every city street in the country was graced with the shade and beauty of chestnuts, elms and maple trees. Those trees are now over 32″ in diameter and considered heritage trees. In the 1930’s, there was another wave of development. Smaller city lots could not accommodate large trees and again many trees were removed. That, combined with the devastation of the elm tree in the early 1900’s due to Dutch Elm disease, resulted in a drastic drop in the number of trees in the urban forest from the 1950’s on. What trees were planted from that era are now 24″ to 30″ in diameter.
These trees, along our streets, on your property and in our local parks, make up the urban forest that deserves your attention. We are all aware of the beauty and the shade trees offer us, but most of us do not recognize that many of our larger trees are suffering from environmental stress and neglect. We do not know that many newly planted trees are not surviving their first few years.
The fact is that unless we protect our trees, a majority of our heritage trees will disappear within twenty to thirty years. The stresses and strains of air pollution, soil compaction and contamination, construction injury, and limited water, oxygen and nutrient availability have taken a toll. Mother Nature can also cause stress to trees with a sudden ice storm, high winds, extreme low temperatures, a devastating spring snowstorm or a summer drought. Many new large growing trees are planted in confined spaces with soil that bears very little resemblance to the rich organic soil of the forest. They are quite removed from their natural environment, and even with organic supplements, the life expectancy of these newly planted trees is only 25 years. It is unlikely they will ever reach the grandeur of our majestic trees today.
Trees are barometers of the changing environment of our ecosystem. The ash tree has been in a slow state of decline for the last 30 years with Ash Yellows disease. We have already lost hundreds and hundreds. There are close to 300 majestic European Beech trees in Winchester, and sadly almost half are seriously affected by summer droughts of the past 10 years and poor soil environments, causing a resurgence of the Beech Bark disease. Without soil amendments, conditioners and added moisture, we run the risk of losing the beech tree which helps to define the beauty of Winchester.
Birch trees have been planted in improper locations with poor soil and water tables, and are succumbing to birch leafminer and bronze birch borer insect infestations. Our hemlocks are threatened by the woolly adelgid which has killed thousands of trees in Connecticut since 1985 and has now arrived in the Winchester area. Particularly susceptible are older and drought-stressed trees.
Trees are slow to respond to wounding and stress. It’s not unusual for trees to die years later following an insult or series of insults. This time delay often leads people to think that a tree wasn’t affected by an adverse event and can’t understand why when the tree dies. Unfortunately, an arborist is typically called when it is evident that a tree is in a state of decline, and by then it is usually too late to save it. Root and branch dieback, decay and foliage scorching are all symptoms of stress and put the tree into a weakened condition. Weakened trees are much more susceptible to insect problems and disease.
While this outlook on the future of our trees seems bleak, it is realistic. Fortunately however, there are several proactive and organic approaches we can take to prolong the life of a tree and maintain the good health and vigor that we want and need in the urban forest. The health of a tree or shrub is much like the health of a human being. People who eat right and exercise are more likely to ward off disease. So it is with a tree – a healthy tree or shrub is better able to ward off and tolerate environmental stress, disease and insect pests.
First and most importantly, we need to fix the soil. By raking our leaves for the past 100 years, we have interrupted the carbon and nutrient cycles that serve to keep trees healthy and growing. We have removed essential organics from the soil that ordinarily would be recycled through decomposition. Without organics and microbial life, soil is deprived of nutrients and oxygen, becomes compacted, and cannot retain moisture. Further, we have contaminated the soil with too many chemicals. Pesticides that rid lawns of insect pests also kill beneficial micro-organisms that work to keep soil alive. The weed controls are the same toxins that also kill trees and woody plants. The time has come to stop using pesticides and herbicides. With the use of humates, soy protein, kelp, enzymes, micro-organisms, calcium and other soil amendments and conditioners, you can replace the depleted organics that we have removed for so many decades. By promoting microbial life, you can correct your soil organically so that it will be the growing medium a tree needs to sustain good health. Everything will benefit, including your shrubs and lawn!
Secondly, a tree needs to be periodically inspected for structural defects, insect pests and disease. Health inspections should be performed at least annually and after major storms, and even more frequently for trees under stress and in high use areas.
Thirdly, trees should be pruned judiciously and properly. Pruning should focus on removing dead, dying, diseased and broken branches. Improper pruning techniques are common stress factors of urban trees and can cause premature decline.
Lastly, proper irrigation and mulching, especially in times of drought, are essential to maintain a tree’s good health.
We must not assume that trees are immortal, that they take care of themselves, or that we can just plant another one if a tree dies. The mature, majestic shade trees that form the canopy over our urban centers and towns deserve a heightened sense of appreciation, protection and care now.