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Abstract
Welch, C.M.
and A.G. Endress. 2008. Successional Changes in an Ongoing Ecological
Restoration at the Grassy Slough Protected Area, Illinois. JEMREST 4:01-10
DOI:
10.4029/2007jemrest4no101
Community
structure during the first six years of habitat restoration was examined at the
Grassy Slough Protected Area, a previously farmed, 1,155-hectare, historic
bottomland forest in southern Illinois.
The purpose of the study was to gauge the progress of successional change and
the extent to which non-native species may be influencing succession at the
site. We expected plant diversity, the
number of co-dominant species, the proportion of perennial woody vegetation,
and native richness index (NRI) to increase after five years. Data collection
occurred in 2000 (one-year-old field) and 2005 (six-year-old field) utilizing
a sampling scheme of 1.0-m2 quadrats randomly placed along permanent
transects. Ninety-eight species were identified in 2000, and 91 in 2005.
Importance values were calculated as the sum of relative frequency and
relative cover. Xanthium strumarium
and Sida spinosa were the most abundant species in 2000, but
abundance shifted to Conyza canadensis and Andropogon virginicus in
2005. The reduced diversity may be due to dominance of the allelopathic A.
virginicus. Non-native species were a significant component initially,
but dominance shifted towards native vegetation as succession
progressed. Compared with earlier old
field studies conducted in nearby upland fields, both diversity and the
proportion of co-dominant species in this bottomland site were greater. The
site is relatively young, and additional sampling will be required to assess
the success of the augmented tree planting, examine the impact of seeding
from nearby populations, and document the influence of non-native species on
succession.
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