Performance of Dionaea muscipula as influenced by developing vegetation

LUKEN, J. O. (Department of Biology, Coastal Carolina University, Conway, SC 29528). Performance of Dionaea muscipula as influenced by developing vegetation. J. Torrey Bot. Soc. 134: 45–52. 2007.— Demography, growth, and flowering of Dionaea muscipula (Venus’ fly trap) were studied during three years (2003–2005) following prescribed fire. Data were collected in permanent quadrats where the developing vegetation was either repeatedly clipped or allowed to grow. Clipping increased light availability at the soil surface. Over the study period, seedling establishment and flowering declined with increasing time since the last prescribed burn. Seedling densities did not differ between clipped and control quadrats, although greater numbers of seedlings grew to adult size in control quadrats and this significantly influenced population sizeclass structure. Clipping had no effect on leaf number or senescence, but plants in control plots were larger and had marginally longer petioles. The plant populations initially mapped in 2003 showed a continuous decline throughout the study and this decline was punctuated by temporary senescence linked to drought conditions. Drought-induced senescence had a persistent influence on plant size. Relatively higher seedling recruitment to the adult population in control quadrats produced an overall population increase of 18% as compared to a 17% decline in the population from clipped quadrats. Dionaea muscipula may have limited ability to respond to increased light availability due to leaf development constraints and repeated droughtinduced senescence. Fire-dependence may best be defined in terms of seedling establishment and stimulation of flowering. Consistent soil moisture is critical to Dionaea muscipula but the species has characteristics that allow persistence across a wide range of vegetation trajectories.