Life, Death, and Energy of a Tree

Abstract

This paper gives the first complete life table for a tree and a tropical plant (the palm Euterpe globosa, in Puerto Rico). There is rapid but declining mortality before the shoot from one in a million seeds reaches the canopy. Mean generation length (not the minimum length usually used) is 100 years. A new set of parameters measures age-specific energy flow. Young trees are most important in nutrient competition, and on 6000 m2 of ground one year-class reduces about one metric ton of carbon throughout its life. Independent estimates confirm aspects of both the life table and the energy table. The energetic cost of reproduction is about a sixth of the net production of an individual (1 percent of the gross production) and about 5 percent of the net production of the population. The realized fitness of E. globosa, as a species, is roughly comparable to that of Homo sapiens. ALTHOUGH THE STUDY OF SURVIVORSHIP has been an important part of animal ecology for 30 or 40 years, there are few studies on plants. Most of these are for herbs, although there are scattered reports of survivorship of seedlings or adults of trees (e.g., Hett and Loucks 1971; Cooper 1960) and shrubs (Roughton 1972). Harper (1967) and Sarukhan and Harper (1973) have reviewed life tables of