In order for us to communicate over cell phones, it is necessary to have a new type of telephone pole called a cell phone tower (or cell phone antenna) placed at proper intervals along our highways and byways. The density of these towers is directly proportional to the human population density. This mathematical principle called "cell tower proliferation" is a new subject for urban ecologists. Unlike unsightly telephone poles spanned by wires, cell phone towers are solitary structures. Cell phone towers transmit radio waves and must be placed above ground, unlike subterranean telephone cables. Wireless cell phones send and receive messages using radiofrequency energy in the 800-900 megahertz portion of the radiofrequency (RF) spectrum. Directional antennas on the towers divide a geographical area into regions of service called "cells." Different cell phone carriers use separate antennas on the same tower. Rather than have obtrusive towers cluttering our cities and countryside, they are now being disguised in many clever ways. Some of these covert forms include trees, cactus, gas station signs, boulders, and even church steeples. Tree towers resembling araucaria trees have six tiers of horizontal branches, each tier bearing a carrier antenna cluster. Each antenna cluster services a separate cell phone carrier.

In order to service increasing numbers of users, cells have to be made smaller. These smaller cells are called "microcells" compared with traditional cell towers that covered a 10 mile cell. Microcells today are often less than one mile, depending on the local population density. In northern San Diego County, I have counted three cell phone towers in the span of one mile. In 2002, industry officials stated that there were more than 128,000 cell phone towers across America. On a Sunday drive in northern San Diego County, I am amazed at how many people are unaware that the lovely evergreens near houses and along roads are cell phone towers.

Along Mission Road between the cities of San Marcos and Vista, there are three species of these recently evolved trees within a span of one mile. They represent three major groups of vascular plants, including palms, conifers and broad-leafed angiosperms. The broad-leafed angiosperm cell phone tree is an evergreen resembling a magnolia. This is yet another example of convergent evolution. There are no deciduous cell phone trees that change colors and drop their leaves during the fall months. Cell phone trees are completely resistant to drought, bark beetles and other insect pests. They are also immune to root rot and other devastating fungal parasites. They never grow or need pruning, and they maintain their shape indefinitely. Unlike living trees, cell phone trees do not require water or mineral nutrients. In fact, they do well in just about any type of soil, even solid concrete. They are not particular about exposure; they can survive in the shade of a large building or in full sunlight. In addition, cell phone trees do not produce pollen or stinky, messy fruits. They are a godsend to hay fever sufferers.

I have not observed any birds nesting in cell phone trees; however, an orb weaver spider made its characteristic web in one of them. There is some concern about harmful radio frequency radiation (RF) emitted from these trees, a controversial subject beyond the scope of this essay. Cell phone signals are in the same frequency range as microwave ovens at about 100 gigahertz. This frequency is 1000 times smaller than ultraviolet light. The following table shows wavelengths of the electromagnetic spectrum which is inversely proportional to energy:

Cell phone trees appear to survive very well with living trees, although they have a definite competitive advantage. Unlike living trees, cell phone trees do not require water or mineral nutrients. In fact, they do well in just about any type of soil. They even flourish in solid concrete. They do well under a variety of slopes and exposures; however, nearby living trees might suffer from overshadowing, especially if they are shade intolerant.

If you are depressed about the rapid urban sprawl in San Diego County, go on a nature drive and try spotting different species of cell phone trees. Enjoy a romantic picnic beneath the shade of one of these evergreens. If you are beyond the romantic stage of your life, just sit beneath one of the lovely trees and reflect back to the days when you sat beneath living trees. At least you should be getting excellent reception with your cell phone, or laptop computer using your cell phone as a modem.