Variation in Growth and Reproduction in the Neotropical Dioecious Palm Chamaedorea Tepejilote

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Abstract
This paper reports the results of an investigation of spatial, temporal and individual variability of survivorship, growth rates and reproductive behaviour of a dioecious palm, Chamaedorea tepejilote, in a high evergreen tropical forest in Mexico. Mortality, number of leaves, stem height increment, number of inflorescences and probability of reproduction were observed for 810 individuals over four years on three permanent plots, each 20 m .times. 30 m in area. Seedlings had the highest mortality. Mature plants that did not reproduce in four years had a higher mortality than those which reproduced. Sexes of C. tepejilote did not differ in mortality among plots. The mean stem height increment of male and female (mature) plants ranged from 6 to 12 cm year-1. Individual variation in height increment over four years varied from 0 to c. 80 cm. Male plants showed spatial variation in growth rate but not females. Males produced significantly more leaves year-1 (2.3) than females (2.0). Both sexes had different rates of production of leaves among years. Number of inflorescences produced plant-1 was positively correlated with the height of the plants in both male and female plants, but males produced significantly more inflorescences than females. The sexes did not show spatial variation in the production of inflorescences among plots. The reproductive behaviour between years varied more in female than in male plants. Males were more constant than females in the probability of reproduction and in the number of inflorescences produced in four years. A few individuals contributed to the majority of the inflorescences produced in the four years studied: seventeen males of forty-seven plants and thirteen females of thirty-five plants produced more than 70% of the total inflorescences in one pilot, and twenty males of forty-five plants and fourteen females of forty-five plants produced also more than 70% of the inflorescences in another one.