Vegetation survey of Tomlin Timber Nature Preserve, Mason County, Illinois.

Tomlin Timber Nature Preserve is a dry to dry-mesic sand forest. When surveyed by the Illinois Natural Areas Inventory in 1976, the overstory was dominated by Quercus velutina (black oak). Sassafras albidum (sassafras) was second in importance, dominated the woody seedling and sapling layer, and was common in the small tree diameter classes. In 2004, 28 years after the initial survey, Sassafras albidum dominated the overstory with an importance value (IV) of 54.9 (possible 200), an average dbh of 24.4 cm, and with most individuals in the 10-40 cm diameter classes. Quercus velutina, in contrast, was second with an IV of 38.5, an average dbh of 62.7, and dominated the larger diameter classes. Dead-standing and dead-downed black oaks were common and averaged 51.7 stems/ha. The change in dominance appears to be due to a combination of natural mortality and oak wilt which was common in the preserve in the early 1980s. A total of 157 vascular plant taxa were documents from the 8-ha preserve.