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Population dynamics of a threatened cactus species: general assessment and effects of matrix dimensionality
Author(s) -
RojasSandoval Julissa,
MeléndezAckerman Elvia
Publication year - 2013
Publication title -
population ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 59
eISSN - 1438-390X
pISSN - 1438-3896
DOI - 10.1007/s10144-013-0378-1
Subject(s) - threatened species , biology , population , fecundity , leslie matrix , curse of dimensionality , population growth , principal component analysis , ecology , statistics , demography , mathematics , sociology , habitat
Harrisia portoricensis is an endemic Caribbean cactus currently under threatened status. In this study we used population projection matrices to evaluate the conservation status of this species and we performed a systematic analysis of the effects of matrix dimensionality on the inferred demographic parameters. Results revealed that population growth rates ( λ ) were 0.946 and 0.961 for the 2007–2008 and 2008–2009 periods respectively, suggesting a declining population with limited persistence ability. Even when the highest elasticity values corresponded to the survival of adults, numerical simulations suggested that increases in either seedling establishment or fecundity could render λ > 1. Our empirical‐based analysis using raw demographic data revealed a clear trend for λ values to decrease with increasing matrix dimension. Stasis and fecundity elasticities were also found to decrease whereas retrogression and growth elasticitites increased with increasing matrix dimension. These results are roughly insensitive to the method used to create matrices of different dimensions. For H. portoricensis , large matrices with narrow classifications were required to minimize variations in λ , highlighting the need for large data sets to assess the convergence of results with matrix dimensionality. Our combined results emphasize that under current scenarios the ability of H. portoricensis for population growth is severely limited. Any management strategy designed for the conservation of this species should consider long‐term monitoring of populations as well as programs that enhance seedling establishment and adult survival.