Emily Dangremond

EFFECTS OF HABITAT TYPE ON PREDATION IN THE ENDANGERED PLANT, LUPINUS TIDESTROMII. Emily Dangremond,¹ Tiffany Knight,¹Biology Department, Washington University, St. Louis, MO.¹

The endangered coastal sand dune plant Lupinus tidestromii experiences fruit predation that severely limits its population growth. Current population models show that if fruit predation were nonexistent, populations of L. tidestromii would increase. Previous studies have shown that the presence of an invasive dune grass, Ammophila arenaria, provides a habitat for deer mice (Peromyscus maniculatus) which prey upon dune plants.

The incidence of fruit predation was measured in and around A. arenaria and compared to the incidence of fruit predation in open dunes, away from A. arenaria. A one-way ANOVA showed that predation is significantly higher in A. arenaria than on open dunes, suggesting that 1) predators take refuge in the A. arenaria and 2) were the A. arenaria removed, L. tidestromii would experience less fruit predation.

A predator exclosure experiment was done to allow mice access to L. tidestromii but exclude larger rodents such as jackrabbits (Lepus californicus). A significantly lower amount of predation was found on plants that were enclosed, suggesting that jackrabbits are partially responsible for fruit predation. Although the identity of the fruit predators is not definitively known, a large-scale sand dune restoration project being planned for Point Reyes National Seashore will remove A. arenaria from the sand dunes. This may decrease the number of predators on Lupinus tidestromii and thus allow the endangered populations to grow.