Document: NIC-3-21-2

Demographic models for carnivorous plants.

GOTELLI, N.J.* ¹ and A.M.ELLISON ²

University of Vermont, Burlington, VT 05405 USA ¹
Mount Holyoke College, South Hadley, MA 01075 USA ²

Abstract:
Because carnivorous plants (CPs) are long-lived perennial species, their population dynamics can be modeled with stage-based matrix transition models. These models describe demographic transitions (mortality and reproduction) between stages and predict stage structure and exponential rates of population increase. However, many aspects of CP biology dictate that more complex models be built. First, most species of CPs live in nutrient-poor environments, and growth and flowering transition probabilities can be affected by nutrient availability. Second, some CPs produce morphological structures that are specialized for photosynthesis ((e.g., phyllodes in Sarracenia) or nutrient uptake (e.g., pitchers in Sarracenia), allowing plants to cope with temporal variation in nutrient supply. Finally, pitcher-forming CPs (Sarracenia, Darlingtonia, Nepenthes) support a community of inquilines whose biological activity contributes nutrients to the plants. These inquilines may regulate the ratio of pitchers to phyllodes. We estimated stage-transition parameters for a population of the northern pitcher plant, Sarracenia purpurea, in an ombrotrophic bog in Hawley, MA. There was a significant mismatch between observed and predicted population size structure, suggesting that this population is not in equilibrium with its current demographic rates. We are currently testing the hypothesis that long-term N saturation and interactions with inquilines in northern bogs shift Sarracenia demographic parameters so that populations do not settle in to a stable stage distribution.

Keywords: carnivorous plants, pitcher plants, population growth, matrix models, inquilines, N saturation, stage structure

This abstract is being presented at: 9:20 AM in session:
Symposium # 19: Carnivorous Plants as Model Ecological Systems.