PARENT SESSION
Poster Session #41: Plant Demography.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
50
Seasonal variation in plant community regeneration response to flooding in two hydrologically-connected inland wetlands.
Cid, Carmen1, Craig, Jennifer1, Ough, Craig1, Rockwood, Amanda1, 1
ABSTRACT- To determine the relationship between soil seed bank composition and standing vegetation in urban, inland wetlands, we assessed species diversity and relative abundance of vegetation bordering two hydrologically-connected ponds, adjacent to a highway, in 1998, 1999 and 2000. Each year, to determine the seasonal regeneration response to natural flooding variation, we took soil samples in early spring and late autumn from 10 permanent plots randomly-located within sunny and shaded 30m transects bordering each pond. We monitored seedling emergence from these soil samples under flooded or saturated conditions in the greenhouse. Flooding reduced emerging seedling species diversity and abundance, especially in soil collected from sunny sites, but the negative effect varied between years and ponds. In flooded soil, a few grasses and sedges predominated, but some dicots were also abundant in flooded soil from sunny, beaver-disturbed sites. Most species emerging from the soil seed bank were not found in adjacent vegetation survey plots, but soil and standing vegetation had similarly high plant species diversity. Spring and autumn soil samples had many of the same plant species emerging. Pond differences in beaver and human disturbance history, and in accessibility to dispersal may help explain spatial and temporal differences in regeneration response to flooding.
KEY WORDS: soil seed bank response to flooding, flooding effects on wetlands, seasonal variation in soil seed bank diversity, beaver/human disturbance effects in urban wetlands