Sala, Anna .
Internal storage resource dynamics in whitebark pine (Pinus albicaulis), a masting tree.
Strong, synchronized fluctuations in reproductive output in plants are known as mast-seeding. While evolutionary advantages of mast-seeding have received much attention, empirical data on the proximate causes are lacking. We measured resource costs of seed production in whitebark pine (Pinus albicaulis), a keystone subalpine species of the Rocky Mountains, during a masting (2005) and a non-masting (2006) year. Whitebark pine seeds are very rich in fat and protein and provide a critical food source for many animals. Leaf nitrogen and phosphorous concentrations were measured during the masting and non-masting years. Total non structural carbohydrates (NSC) and lipids were also measured in leaves and sapwood during the non-masting year. Seed production significantly depleted needle nitrogen during masting and non masting years. Phosphorous concentrations decreased only in older needles of cone-bearing branches during masting year. During the non-masting year, there was a decrease of lipids and NSC in the sapwood at the base of the tree from pre to post seed production. However, the concentration of P, NSC and lipids in the sapwood of terminal branches increased significantly from pre to post seed production regardless of branch reproductive status. Our results indicate that seed production in whitebark pine is costly and suggest complex resource allocation patterns with preferential resource storage in the sapwood of terminal branches at the end of the season. Such strategy may provide a proximal storage resource pool which allows masting species to take advantage of situations when several conditions converge to allow large reproductive events in the following season (e.g. pollen availability, sufficient resource levels, and favorable weather).
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1 - The University of Montana, Division of Biological Sciences, Missoula, Montana, 59812, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 11:00 AM