PARENT SESSION
Oral Session # 37: Invasive Species III: Grasses and Shrubs.
Presiding: C Lortie
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 205.
Seed production, dispersal, and age determination of Potentilla recta L., an invasive non-native species in northeast Oregon.
Dwire, Kathleen *,1, Parks, Catherine2, Perkins, Dana3, McInnis, Michael4, Read, Bridgett2, 1 USDA Forest Service, Laramie, WY, USA2 USDA Forest Service, LaGrande, OR, USA3 USDI Bureau of Land Management, Challis, ID, USA4 Oregon State University, Corvallis, OR, USA
ABSTRACT- Sulfur cinquefoil (Potentilla recta L., family Rosaceae) is an invasive, herbaceous perennial, native to Eurasia. It has a wide ecological amplitude and has become established throughout North America in numerous habitat types. We suspect that the range of sulfur cinquefoil, although rapidly expanding, is underestimated because the plants frequently co-occur with native Potentilla species, and are misidentified as native. Sulfur cinquefoil reproduces only by seed (achenes). To characterize its demography and seed ecology, we quantified seed production, measured seed dispersal, and aged plants from sulfur cinquefoil infestations in different habitats in northeast Oregon. Seed production for 2 years was 3-4 times higher than previously reported (mean = 5600 seeds per plant; range = 2770 to 8870 seeds per plant). Seed dispersal was measured using sticky traps (30 x 100 cm, replaced every two weeks) radiating in four cardinal directions from individual plants. Seeds fell from early July through September (2001 and 2002), and were mostly dispersed within 1 m of the parent plant. Distribution patterns of sulfur cinquefoil also strongly suggest that human and animal-mediated dispersal contribute to satellite expansion at multiple spatial scales. Plant age was determined by counting annual rings in the primary taproot, which were cross-sectioned just below the root crown and stained. Preliminary results indicate that most plants are 4-6 years old (maximum 12 years), and that stand age is related to local disturbance events. Ongoing research on sulfur cinquefoil in the Pacific Northwest includes studies on seed germination, seed bank viability, population genetics, construction of population models, pollination biology, and response to herbicide and controlled burn treatments.
Key words: sulfur cinquefoil