PRESENTATION
L.E. Gorham(1), B.D. Keeland(2), G. Weisbrich(3), C. Wells(2), and S. Mopper(4) lance.gorham@vt.usda.gov
(1) USDA ‐ NRCS, 59 Waterfront Plaza, Suite 11, Newport, VT 05855‐4877
(2) USGS, NWRC, 700 Cajundome Blvd., Lafayette, LA 70506‐3152
(3) 3509 Lois Lane, Harrisburg, SD 57032
(4) Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70504
Abstract
Herbaceous and wood vegetation recovery following hurricane damage is dependent on several factors, including amount of damage, rates of individual and species survival, levels of advance regeneration, amount of natural invasion, and the soil seed bank. To study the impact the soil seed bank has on subsequent recovery we collected soil samples from 120 tree tip‐up mounds, associated depressions, and adjacent undisturbed soil from two hurricane‐impacted wetland forests, two years after Hurricane Andrew. We exposed these samples to three hydrologic treatments (dry, moist, and flooded) for two months and monitored plant germination. Soils originating from mound and depression microhabitat had significantly more plants germinate than the undisturbed soils. Species specific responses included Boehmeria cylindrica. and Symphyotrichum racemosum exhibiting significantly greater germination in undisturbed soils, whereas Mitreola petiolata was more frequent in the mound soils. To ascertain the effects of long‐term hydrologic fluctuations on seed germination, we subdivided the original soil units into three groups and re‐exposed them to one of the three hydrological treatments for an additional two months. In this second growth period, depression soils and moist conditions produced the greatest plant abundance. Mitreola petiolata was significantly more abundant in depression and mound soils than in the undisturbed microhabitat. This study shows that mound and depression microhabitat serves as a seed repository within two years of the blowdown. In addition, hydrologic conditions influenced the species and numbers of individuals which were able to germinate and grow from the seed bank. |