Conceptual and methodological issues in structured population models of plants

Abstract

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.

Botanical Sciences : an honorable fellow in the international assembly of botanical journals

“…Their analysis highlights the urgency to embark on new physiological research on CAM plants, as they may play an important role in future scenarios of climate change. Martorell et al (2022) center on the use of two kinds of structured projection models (discrete matrix projection models and continuous integral projection models) to study the dynamic properties of plant populations whose individuals are classified according to different criteria (i.e., not all individuals are equal). The authors highlight the versatility of these models, which have already been used to examine the dynamics of numerous populations of a large variety of species.…”

The effect of habitat transformation on a twig epiphytic orchid: Evidence from population dynamics

“…pseudobulb and inflorescence number(Ospina-Calderón, 2009), and the methodology for PPM developed for orchids, followingTremblay and Hutchings (2002) andMartorell et al (2022). Our simplified life history of R. granadensis is based on four size classes describing the life stages: (1) Seedling (S), individuals lacking pseudobulbs; (2) Juvenile (J) with 1-2 pseudobulbs; (3) Small adults-stage 1 (A1), possessing 3-6 pseudobulbs and no more than one inflorescence; and 4.…”