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Patterns of Growth and Reproduction of Geonoma congesta, a Clustered Understory Palm
Robin L. Chazdon
Vol. 24, No. 1 (Mar., 1992), pp. 43-51
Published by: Association for Tropical Biology and Conservation
Stable URL: http://www.jstor.org/stable/2388472
Page Count: 9
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Clone structure, growth characteristics, and reproductive behavior of individual ramets and clones were investigated over a 3 yr period for Geonoma congesta ("cana de danta"), an abundant understory palm of the Atlantic lowland forest in Costa Rica. The 0.6 ha study area contained 123 clones. Mean clone size was 7.1 ramets; only 3 percent of the clones sampled had more than 20 ramets. Within a clone, new ramets are produced sporadically, 1 to 4 ramets at a time. Ramet mortality is often associated with physical damage from falling trees, lianas, and branches. Less than 30 percent of the ramets with stems were erect. Over 58 percent of stemmed ramets were bent or otherwise leaning; whereas, 11.6 percent had been forcibly smashed to the ground. Ramets produced on average 10.1 new leaves and abscised 9.7 leaves in 3 yr. Rates of leaf production and leaf abscission did not vary significantly among ramet stage classes. Stem elongation was greatest in shorter, younger ramets. In taller, older ramets, leaf size and number decreased over the study period. Reproductive clones comprised 64 percent of the clones in 1986; whereas, only 24 percent of individual ramets reproduced. Ramets that reproduced every year had significantly larger leaves and substantially greater crown leaf area than the other reproductive classes. Stage classes with the greatest frequency of reproduction exhibited the greatest decrease in both crown size and leaf size. Individual ramets are estimated to live an average of 60-70 yr; whereas, clones may persist for 100 yr or more. The growth form of Geonoma congesta ensures that clones persist despite a high incidence of ramet mortality and damage. Moreover, at least one ramet within a clone is likely to reproduce every year, although individual ramets may not reproduce every year. Patterns of growth and reproduction in G. congesta are consistent with the hypothesis that the growth of young, deeply shaded sprouts is supplemented by production from older, taller stems.
Biotropica © 1992 Association for Tropical Biology and Conservation