Effects of Tree Characteristics

A tree's genetics, crown size, and ability to tolerate shade and competition from other plants influence how well it will grow in different environments.

Genetics affects many aspects of tree form and growth, including the rate of height and diameter growth, stem form, crown form, any tendency to self-prune, the angle of branch attachment, and tolerance to insects and diseases. You must decide which of these traits is important in helping you achieve your objectives for your woodland. For example, when relying on natural reproduction, kill or harvest undesirable trees during intermediate and final harvests. Permit only desirable trees to produce seed, stump sprouts, or root suckers. When growing trees for timber, poor-quality trees may be an acceptable seed source if their rough appearance is a result of stand conditions or damage not related to genetic characteristics. When planting seeds, seedlings, or cuttings, use planting materials from a reputable tree nursery that collects seed or cuttings from high quality trees growing as close to your planting site as possible. Depending on your needs, the seed source also may exhibit one or more of the form and growth characteristics listed above.

Figure 3-2: Live-crown ratio of a treeTrees with large crowns have more leaves and, therefore, normally grow faster in height and stem diameter than trees with small crowns. The live-crown ratio of a tree is the percentage of total tree height that has live branches on it.

For timber production purposes a live-crown ratio of approximately one-third often is optimum, but the optimum percentage varies by species. If the crown is too small, the tree will grow slowly. If a crown is too large, there will be too much wood in the limbs and too little in the more usable main stem.