PARENT SESSION
Contributed Oral Session 83: Human Impacts on Coastal Areas
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Highly variable spatial and temporal patterns of seedling recruitment in invading populations of Spartina alterniflora.
Lambrinos, John*,1, Strong, Donald2, Civille, Janie1, Bando, Jun1, 1 Department of Environmental Science and Policy, Davis, CA, U.S.A.2 Section of Evolution and Ecology, Davis, CA, U.S.A.
ABSTRACT- Across much of its native range, vegetative growth dominates the population dynamics of Spartina alterniflora. Contrastingly, in Willapa Bay, WA the spatial expansion of invading S. alterniflora populations has been driven primarily by seedling recruitment. We measured this recruitment at the landscape scale using a series of precision GPS guided airboat censuses. Recruitment is highly variable across both space and time. Over five years of observation, the yearly average estuary wide recruitment varied from a low of 12/ha to a high of 500/ha. Variability across individual census plots was even greater, ranging from 0/ha to over 4000/ha. Several factors influence this variability: 1) local recruitment tracks variation in local seed production 2) tidal elevation and hydrological conditions influence the spatial pattern of seed deposition and retention 3) substrate characteristics independent of elevation and hydrology influence seedling survivorship and growth. These results indicate that despite long distance dispersal local seed production and site characteristics strongly influence local recruitment dynamics. In addition, the strongly episodic nature of recruitment suggests that the efficacy of restoration and invasive control can also vary tremendously between years. The ultimate success of both native restoration and invasive control will likely be greatly improved with an explicit recognition of this spatial and temporal variability.
Key words: dispersal, landscape heterogeneity, management, tidal wetland