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Monday, April 9 • 5:30pm - 7:00pm
POSTER: How Does Soil Nutrient Availability Influence Mast Seeding Dynamics of White Spruce?

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AUTHORS: Abigail C. Leeper*, DePaul University; Beth A. Lawrence, University of Connecticut; Jalene M. LaMontagne, DePaul University

ABSTRACT: Mast seeding is the synchronous production of highly variable seed crops across years by a population of perennial plants. The strength of mast seeding is described by the variability in reproduction as the coefficient of variation (standard deviation / mean; CV). While there are several hypotheses used to explain mast seeding, the resource matching hypothesis states individuals reproductive output reflects the available resources (e.g. soil nutrients). While mast seeding is often studied at the population level, it is individual trees that produce the pattern, and are the focal unit for our study. Furthermore, in North America, the impact of soil nutrients on the reproductive output of mast seeding individuals has not been studied in depth, and may have a large influence over the mast seeding dynamics. To test the hypothesis that soil nutrient levels influence mast seeding patterns, and the prediction that increased nutrients (in particular nitrogen) will lead to lower variability in mast seeding and higher mean cone production, we deployed sets of Plant Root Simulator Probes for 6 weeks in each of the summers of 2016 and 2017 to record macro- and micronutrient availability at 114 individual white spruce (Picea glauca) trees in the Huron Mountains, Michigan, USA. We estimated cone production for these individuals from 2012 to 2017, from which we calculated CV. Additionally, we recorded diameter at breast height in 2012 and soil moisture at probe burial and retrieval in 2016. We found that CV was not significantly influenced by soil nutrient availability. However, larger trees had both higher mean cones per unit basal area, and lower variability (CV) in cone production over time. There is considerable unexplained variation in individual reproduction patterns, and factors such as soil moisture, and trade-offs in growth and reproduction may both play a role.

Monday April 9, 2018 5:30pm - 7:00pm CDT
Monroe Room

Attendees (2)