Vegetation composition, structure, and diversity patterns of two dry sandstone barrens in southern Illinois

John B. Taft, Mary Kay Solecki

Research output: Contribution to journalArticlepeer-review

Abstract

Vegetation at two dry sandstone barrens in Pope County, Illinois was sampled to provide baseline data on composition, structure, diversity, and species-abundance patterns for comparison with vegetational changes resulting from applications of prescribed fire. Permanent plots were established at both sites. Data were collected from canopy, subcanopy/shrub, and ground-cover strata. One site, Gibbons Creek Barrens, is the fire treatment site while the other, Forest Service Barrens, serves as a fire-free control site. The vegetation at these barrens remnants is similar in many regards facilitating their use as treatment and control units for experimental study of fire effects. Both sites are dominated strongly in the canopy by Quercus stellata Wangh. The subcanopy shrub/sapling stratum is dominated by Ulmus alata Michx.; however, several other taxa are common to occasional. Size-class distribution of over-story trees suggests a pattern of change characterized by stand closure as recruitment of Quercus stellata and Ulmus alata alters the open barrens structure. Patterns of subcanopy recruitment and tree size-class distribution support an interpretation of sites that are compositionally stable and structurally unstable in the over-story. The same six ground-cover species are the most abundant species at both sites; however, rank abundance differs. At Gibbons Creek Barrens the dominant herbaceous species is the C4 prairie grass Schizachyrium scoparium (Michx.) Nash, while at Forest Service Barrens the dominant species is the C3 dry woodland grass Danthonia spicata (L.) Beauv. Ground-cover species are distributed in somewhat discrete patches with C4 grasses occurring in open areas, C3 grasses and sedges more generally distributed but predominating in more closed areas, and several open woodland species occurring in the barrens edges and where Q. stellata is in relatively low abundance. Ground-cover species diversity is correlated inversely with density of Quercus stellata. Stand areas exceeding about 25 trees per 0.05 ha particularly have lower diversity suggesting a benchmark for vegetation management designed for maintaining vegetational diversity. Both sites appear to be high-quality natural areas, support a rich assemblage of native species, and lack an adventive flora.

Original languageEnglish (US)
Pages (from-to)343-368
Number of pages26
JournalCastanea
Volume67
Issue number4
StatePublished - Dec 2002

ASJC Scopus subject areas

  • Plant Science

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