Urban Stress in Plants and Trees

Urban Stress

There are many factors that stress out plants and trees around our area. Because we are located in an urban setting, these plants and trees are more vulnerable to such stress. During our walk around campus, I noticed an enormous amount of stress done to the plants and trees. In this essay, I will explain my observations of urban stress around Temple University's campus and how each factor plays an important role and how it influences the survival of each plant and tree.

Heat stress was a major factor I noticed around campus. Asphalt and concrete areas reflect and hold in heat from the sun, which in turn, scorch many of the plants and trees on campus. Ranging from burned, dried out leaves to dried soil, these surfaces are very harmful to these plants and trees. Raymond A. Cloyd explains, "Another factor that can lead to increased plant stress is the amount of "hardscape," such as parking lots and buildings that surround plants. An increase in heat absorption, light reflection or an inadequate water supply creates a microclimate that is stressful to plants". However, lack of heat also stresses out plants and trees on campus. Because we have such high buildings and trees, the sun cannot get to some of the plants and therefore, these plants and trees won't grow properly.

Moisture Stress is another factor that can either harm a plant or a tree. Because the lack of rainfall this year, I noticed a lot of moisture stress related problems. Lack of rainfall limits the amount of nutrients needed to help plants and trees grow, there I noticed a few immature-looking plants along with dried out ones as well. However, excess moisture to a plant can have harmful effects to the plant and tree also. According to Bert M. Cregg and Mary Ellen Dix, "Increasing moisture stress can limit tree growth and reduce survival through direct and indirect effects on an array of physiological processes including photosynthesis (Cregg 1995), respiration, protein synthesis, and secondary carbohydrate metabolism (Kramer 1987)". A plant or tree can hold only but so much water, therefore, over watering it can have harmful effects to it and not watering at all, because of our lack of rainfall, will also have harmful effects to it.

One man made stress factor to these plants and trees are improper care of them. For example, around campus, I noticed many instances of improper pruning. There are two types of improper pruning, according to Cloyd. These two types are poor practices and improper timing. Cloyd further explains:

Examples of poor practices include pruning in a manner that stimulates succulent growth, which is attractive to insects such as aphids and planthoppers; leaving stubs; topping trees or cutting too far back into the branch collar. These practices often make it difficult for plants to properly heal themselves, which leads to insect problems such as wood-boring beetles. Improper timing includes 1) pruning plants when insects,

especially egg laying females, are most active; and 2) pruning when plants are most likely to produce volatile chemicals that attract insects. Pruning during winter dormancy typically avoids timing problems.

Another example of improper care is mulching. Cloyd explains, "Proper mulching can lead to healthy plants. It reduces in weed competition, helps plants retain more soil moisture and prevents damage to the base of trees and shrubs from lawn mowers