Chemistry of Trees and Plants

With our term's topic being urban naturalization, a large part of our educational efforts is on promoting the use of native plants in urban settings. Our soon to be announced website will have detailed information on what urban naturalization is and what the benefits.

In anticipation of that, I thought it would be interesting to give an explanation of what plants do, chemistry wise, that benefits the environment.

Clean Air
Trees and plants natural clean our air. Their source of energy is carbon, from carbon dioxide gas. Plants use water, carbon dioxide and sunlight to create sugars, which can be broken down for energy. That is the photosynthesis cycle.

Conveniently, human breathing gives off carbon dioxide as a "waste product". Plants then use the carbon dioxide and give off oxygen as their "waste product", which then benefits humans. This circular system is replicated many times in nature. For example, the water cycle and the food chain.

Usually when man made innovations change something from a circular to linear system, undesirable side effects can occur. If this idea interests you, the book Cities, People, Planet by Herbert Girardet may be of interest.

Many trees have leaves that change colors in the fall. This happens because the green chlorophyll, which makes the energy, stops working. Shorter days and temperature changes cause this. As the chlorophyll die, the green goes away to reveal other colors. Plants start to produce other colored pigments through chemical reactions.

While the largest benefit that humans get from this is appreciation of the colors, there may some biological significance to color change. The colored pigments could be beneficial in controlling aging. The color changes could also work in tandem with animals as indicators of whether they should or should not interact with the plant. Research is still being done in this area.