PARENT SESSION
Oral Session # 92: Biogeography IV: Dispersal.
Presiding: J Choo
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 104.
Seed dispersal by white-tailed deer: Implications for long-distance dispersal and plant migrations.
Vellend, Mark *,1, Myers, Jonathan1, Gardescu, Sana1, Marks, Peter1, 1 Cornell University, Ithaca, NY, USA
ABSTRACT- For many plant species in eastern North America, observed seed dispersal distances (ranging up to only a few tens of meters) fail to explain inferred rates of post-agricultural colonization and post-glacial migration. This discrepancy points to a substantial gap in our knowledge concerning the mechanisms by which seeds are dispersed long distances. Here we report seed dispersal of >70 plant species via ingestion and defecation by white-tailed deer in central New York, USA. This is the first comprehensive study of seed dispersal by white-tailed deer, despite a vast body of research on other aspects of white-tailed deer ecology. The plant species dispersed by deer include herbs, shrubs, and trees from a variety of habitats, and the full range of presumed dispersal modes in eastern North America (ants, wind, vertebrates, ballistic, and unassisted). We found a mean of >30 germinable seeds per pellet group, and seeds were dispersed during all months of the year. The majority of seeds found possessed no obvious adaptations for dispersal. Notable taxa included Trillium grandiflorum, an otherwise ant-dispersed forest herb, and four of the top 20 invasive plants of greatest concern in New York State: Lonicera spp., Rosa multiflora, Rhamnus cathartica, and Lythrum salicaria. A deer-generated seed shadow modeled using data from the literature on movement patterns and gut retention times revealed that most deer-dispersed seeds should travel several hundreds of meters, and occasionally >3 km. We conclude that white-tailed deer represent a significant and previously unappreciated vector of seed dispersal across the landscape, likely contributing an important long-distance component to the seed shadows of hundreds of plant species, and providing a mechanism to help explain rapid rates of plant migration.
Key words: long distance seed dispersal, large herbivore, eastern North America, post-glacial migration