Abstract

MARTORELL, Carlos; FLORES-MARTINEZ, Arturo  and  FRANCO, Miguel. Conceptual and methodological issues in structured population models of plants. Bot. sci [online]. 2022, vol.100, n.spe, pp.110-136.  Epub Oct 17, 2022. ISSN 2007-4476.  https://doi.org/10.17129/botsci.3105.

Structured projection models (SPMs) are a powerful tool to investigate the dynamics of structured populations, which makes them ideal for the study of plant species spanning their range of life forms, sizes, longevity, and life cycle complexity. They are one of the most versatile tools in plant ecology, with hundreds of species studied so far and a wide variety of alternative formulations for different questions and purposes. We revise some of the most salient conceptual and methodological issues in the construction and use of SPMs including both discrete matrix projection models and continuous integral projection models. Consideration is given to the selection of the state variable and the estimation of parameters, especially those involving transitions difficult to observe in the field, such as the quantification of offspring production and the rarely observed mortality of individuals towards the end of the life cycle. Due to the growing importance of investigating population trends in a rapidly changing world, we highlight the use of SPMs for populations under a variety of environmental influences and/or away from their expected equilibrium. The presumed role of population density receives special attention because it often correlates with features of the environment, thus potentially confounding the two effects. Similarly, disentangling the various environmental effects poses challenges of its own, making it difficult to prove causality. The alternatives available are illustrated considering the selection of variables, samples, and model type suitable for specific purposes.

Keywords : density dependence; environmentally explicit projection models; model complexity; model parameterisation; spatial demography; transient dynamics.

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