Population structure in Zamia (Zamiaceae) in northern Puerto Rico. II. Seed germination and stage-structured population projection

Population biology has been studied in few species of cycads, and these studies have focused on adult demography. We investigated all life-history stages, including seed germination and recruitment, of Zamia amblyphyllidia over 3 yr in Cambalache Forest, Puerto Rico, and constructed stage transition...

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Bibliographic Details
Published in:International journal of plant sciences 1996-09, Vol.157 (5), p.605-614
Main Authors: Negron-Ortiz, V. (Fairchild Tropical Garden, Miami, FL.), Gorchov, D.L, Breckon, G.J
Format: Article
Language:English
Subjects:
BOSQUES
Botany
CONE
CONES
coning
CONOS
CRECIMIENTO DE LA POBLACION
CROISSANCE DE LA POPULATION
DEMOGRAFIA
DEMOGRAPHIE
DEMOGRAPHY
DISEMINACION DE SEMILLAS
DISSEMINATION DES GRAINES
Dry seasons
ECOLOGIA
ECOLOGIE
ECOLOGY
EMERGENCE
EMERGENCIA
ESTADO JUVENIL DE LAS PLANTAS
ESTRUCTURA DE LA POBLACION
FECUNDITY
FENOLOGIA
FERTILIDAD
FERTILITE
FERTILITY
FEUILLE
Flowers & plants
FORESTS
FORET
FRUCTIFICACION
FRUCTIFICATION
FRUITING
GERMINACION
GERMINATION
HOJAS
JUVENILITY OF PLANTS
LEAVES
LEVEE
MORTALIDAD
MORTALITE
MORTALITY
PHENOLOGIE
PHENOLOGY
Plant reproduction
Plants
PLANTULAS
PLANTULE
POPULATION ECOLOGY
POPULATION GROWTH
Population growth rate
POPULATION STRUCTURE
PORTO RICO
PUERTO RICO
RADICLE
RADICULA
RADICULE
RECRUITMENT
SEED DISPERSAL
Seed germination
SEEDLINGS
Sex ratio
STADE JUVENILE DES PLANTES
STRUCTURE DE LA POPULATION
subtropical forests
ZAMIA
zamia amblyphyllidia
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Summary:Population biology has been studied in few species of cycads, and these studies have focused on adult demography. We investigated all life-history stages, including seed germination and recruitment, of Zamia amblyphyllidia over 3 yr in Cambalache Forest, Puerto Rico, and constructed stage transition matrices from our field data. We found two distinct stages in seed germination: radicle emergence and, 1-7 mo later, leaf emergence. Seeds released from cones early, before the onset of the dry season, germinated faster but suffered greater mortality during the first dry season than seeds released 2 mo later. However, after 3 yr both early and late seed cohorts had similar survivorship (2%-3%). We categorized plants to be seedlings, juveniles, or adults based on the number of leaflets on the longest leaf, as cone production was almost nonexistent among plants with ≤10 leaflets. Most "adults" did not cone over the 3 yr of the study. Despite low probability of coning among females, low fecundity of coning females, and low recruitment of seedlings to juveniles, the population was projected to have a finite rate of increase, λ, of nearly 1.0. High annual survivorship of adults, combined with episodic coning, appears to account for the persistence of Z. amblyphyllidia populations.
ISSN:1058-5893
1537-5315
DOI:10.1086/297381