Distribution Patterns of Foliose and Fruticose Lichens of Eastern Iowa

Abstract

Seventy-two species offoliose and fruticose lichens are reported for eastern Iowa, ten of them new records for the state. This flora shows greatest affinity with the eastern North American floristic region and has few species with a boreal, tropical or southwestern U.S. distribution. Until recently, the lichen flora of Iowa was largely unreported. However, in the last five years, several studies (Malone & Tiffany 1978; Schutte 1979; Dunlap & Tiffany 1980) on either a statewide or local level have provided a floristic base for lichen study in this area. Because of its central location, Iowa exhibits floristically diverse vascular plants, with elements of the tallgrass prairie, eastern deciduous forest, northern coniferous forest and Atlantic coastal plain being most common (Lammers & Van Der Valk 1978). However, ecological diversity has been reduced by extensive farming. Original or second-growth vegetation does remain in state and county parks and pre- serves, and along rivers where the land is unsuitable for agricultural use. Upland forests are dominated by Quercus, Carya, and Juglans, while lowland forests contain more Acer, Tilia, and Ulmus (now declining). These woodlands have few native conifers, although Juniperus virginiana may be frequent in dry sites. There are some stands of native Pinus strobus, and groves of non-native conifers have been planted in many areas. Very little native Iowa prairie remains, although a few communities of tallgrass prairie have been preserved. Most of the rock available for saxicolous lichens in eastern Iowa is limestone, found in outcrops along river valleys. Bryophytes also find these limestones suitable habitat, and lichens may be epiphytic on the bryophytes. Soils vary from the alfisols of the forests to the mollisols of the tallgrass prairie, but the sand prairie communities have the most extensive terricolous lichen assemblage. These soils are generally coarse to fine sand, with little organic matter, and rapid drainage. The purpose of this study is to present an annotated flora of the foliose and fruticose lichens of eastern Iowa, and to examine the affinities of this flora with other areas of North America.