Hurricane disturbance and the population dynamics of a tropical understory shrub

Megamatrix elasticity analysis

John B. Pascarella, Carol C Horvitz

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

The role of environmental variation in the population dynamics of the tropical understory shrub Ardisia escallonioides was explored using single-environment matrix analysis and dynamic-environment megamatrix analysis. We investigated how variation in forest-canopy openness caused by hurricanes affected population dynamics. A 7 X 7 patch-transition matrix was created to model forest dynamics based on the historical frequency and strength of hurricanes in south Florida. Seven 8 x 8 stage-classified matrices for plant population dynamics were derived from four field populations and two posthurricane years. These populations spanned a strong gradient of forest-canopy openness resulting from hurricane disturbance caused by Hurricane Andrew (24 August 1992). The patch-transition matrix was analyzed for its stable patch distribution. The seven single-environment matrices were each analyzed for population growth rates and elasticity of stage classes. The 56 x 56 megamatrix was analyzed for population growth rate, reproductive value, stable patch-stage distribution, and elasticity of both patches and stages. Population growth rate of the single-environment matrix models (8 x 8) was lowest for the shadiest environment (λ = 1.0), intermediate but Variable for intermediate environments, and highest for the most open environment (λ = 1.96). The population growth rate (λ,) of the megamatrix model was 1.71. The stable patch-stage distribution was characterized by a high proportion of seeds in open patches. Reproductive value was highest for very large adults in open patches. Megamatrix elasticity analysis revealed several components of the demography that were not apparent from examination of the single-environment matrices. Although closed-canopy patches were the most common type of environment, elasticity analysis of the megamatrix showed that the highest patch elasticity was for the most open environment. We found contrasting predictions for the relative importance of life history stages to population growth rate from single-environment analysis vs. the megamatrix analysis. In the most common single-environment patch, very large adults had the highest elasticity. In the megamatrix, small juveniles contributed the most elasticity and all stages contributed some elasticity. For plant species inhabiting temporally varying environments, megamatrix analysis offers new insight into the importance of both patches and stage classes.

Original languageEnglish
Pages (from-to)547-563
Number of pages17
JournalEcology
Volume79
Issue number2
StatePublished - Aug 28 1998

Fingerprint

hurricanes
elasticity (mechanics)
hurricane
understory
elasticity
population dynamics
shrub
shrubs
disturbance
population growth
matrix
forest canopy
analysis
Ardisia
forest dynamics
demography
life history

Keywords

  • Ardisia escallonioides
  • Elasticity
  • Hurricanes
  • Megamatrix analysis
  • Patch dynamics

ASJC Scopus subject areas

  • Ecology

Cite this

Hurricane disturbance and the population dynamics of a tropical understory shrub : Megamatrix elasticity analysis. / Pascarella, John B.; Horvitz, Carol C.

In: Ecology, Vol. 79, No. 2, 28.08.1998, p. 547-563.

Research output: Contribution to journalArticle

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