SEED BANK-VEGETATION RELATIONSHIPS IN HERBACEOUS CAROLINA BAYS: RESPONSES
TO CLIMATIC VARIABILITY
John
M. Mulhouse,a Laura E. Burbage,b and Rebecca R.
Sharitza,a, c
Author Affiliations
aUniversity of Georgia Savannah River Ecology Laboratory Drawer
E Aiken, South Carolina, USA 29802
bUniversity
of Georgia Institute of Ecology Athens, Georgia, USA 30602
cAuthor for correspondence (E-mail: sharitz@srel.edu)
Abstract
Vegetation in intermittently flooded wetlands is strongly affected by
the influence of hydrologic condition on species establishment and survival.
The vegetation of four herbaceous depression meadow Carolina bay wetlands
on the Upper Coastal Plain in the southeastern USA was sampled while systems
were flooded in 1999 and again in 2002, near the end of a multi-year drought
during which all bays were dry. The seed banks of these bays were sampled
in the spring of 2000 and their relationship to the extant vegetation
at both ends of the hydrologic spectrum examined. All bays lost previously
abundant perennial aquatic species during the drought, and grasses, especially
a rhizomatous perennial, Panicum hemitomon, expanded. While approximately
half the species in the vegetation were also found in the seed bank, more
than 60% of species in the seed bank were never detected in the vegetation.
Also, widespread species in the vegetation, especially grasses and aquatic
herbs, were rare or absent in the seed bank. The results of the study
were consistent with a cyclic model of herbaceous Carolina bay vegetation
dynamics in which aquatic and grass species dominate in turn as climate
oscillates between wet and dry periods. Further, it appears that, in herbaceous
Carolina bays, a handful of dominant aquatic and grass species in the
vegetation may influence composition more strongly than widespread recruitment
from the seed bank as hydrologic condition fluctuates.
Keywords
Carolina bays, depression wetlands, drought, plant colonization, succession.
SREL Reprint #2894
Mulhouse,
J. M., L. E. Burbage and R. R. Sharitz 2005. Seed bank-vegetation relationships
in herbaceous Carolina bays: responses to climatic variability. Wetlands
25:738-747.
