A Concise Guide To Trees.

Introduction

  Trees have been called the structural elements of the ecosystem. They form the most noticeable living objects except in the driest and coldest climates. Trees have whole communities of other organisms associated with each type. Some birds or insects are found only in broad-leaved trees, others in conifers. In addition, trees form levels in which these communities of other animals are found. Blackburnian Warblers are found at the tops of trees, Canada Warblers lower down. Nuthatches, Brown Creepers, and Woodpeckers are typically found on the trunks and larger branches.

Most botanists define trees as woody plants having a single stem and growing at least 10 feet tall -- the height of a basketball goal. Other definitions are used, but they are similar. A shrub or bush, on the other hand, is a woody plant having multiple stems growing from the same roots and is usually lower growing. An oak is a tree. Most lilacs are shrubs. At the other end, trees can be gigantic. Some species, like Giant Sequoias, Coast Redwoods, Douglasfirs, and some Eucalyptus, grow 300 feet tall or more and have trunks 30 feet across. Some species also have very long life spans. The Great Basin Bristlecone Pine often lives longer than 4,000 years.

That's right, four thousand. Some trees living today are as old as the most ancient pyramids of Egypt. They were living when civilization began in the Indus Valley and the earliest dynasties of China were founded. These trees were unimaginably ancient when Troy fell to the Greek invaders. More than half their lifetime had passed by the time Christ was born. The Norman invasion of England, the Viking discovery of North America, and the Mongol Empire are recent history to them. Whole forests of several species are alive now that were old when the first permanent European settlements in the new world were founded.

Different kinds or species of trees can be told apart in many ways, some of them available to the blind. The feel of the leaves, twigs, and bark varies from species to species. Some trees have distinctive odors. Even the sounds the wind makes in the trees can be different depending on the kind of tree. And some birds are heard in one kind of tree, but not in others.

While the general concepts in this brief introduction are accurate for most parts of the world, the specifics here deal with North America.