Identifying Reference Conditions for Riparian Areas of Ohio

Special Circular 192

Summary of Different Survey Types

The first descriptions of the major pre­European settlement forest types for Ohio were developed by Sears (1925) and Sampson (1927), who transcribed the species of bearing or witness trees from the original land surveys conducted in the late 1700s and early 1800s. Sears (1925) classified each township in the state as fundamentally "beech," "oak," or "ash" or various combinations of these types and classified treeless areas into "prairie" types (Sears, 1926).

Transeau and Sampson (1938) also used these original land surveys in conjunction with field studies of remaining undisturbed forests in an effort to classify major forest types, including swamp forests, and develop strategies to better utilize Ohio's forests. Sampson (1927) mapped major plant associations and suggested that the riparian forests of the state were dominated by willow, alder, river birch, and maple-cottonwood-sycamore forest associations.

A similar pre-European forest-type classi­fication as Transeau and Sampson (1938) was developed by Chapman (1944). However, Chapman was the first to provide a reconstructed picture of the pre-European settlement riparian forests, as he documented that elm, ash, soft maple (e.g., red maple), sycamore, burr oak, pin oak, and cottonwood dominated the floodplains of larger streams and rivers, while smaller streams flowing through narrow valleys throughout the state were dominated by hemlock, American beech, and maple.

The most detailed description of the pre-European forests of Ohio (Figure 1) was developed by Gordon (1966, 1969), who synthesized the work of Sears (1925), Transeau and Sampson (1938), and Chapman (1944), as well as many county-level forest-type classifications published as M.S. theses, Ohio Biological Survey (OBS) reports, and state forestry reports published by the Works Progress Administration and the Ohio Agricultural Experiment Station (OAES). For example, Gordon (1969) described major plant associations for different floodplains and swamp forests; however, he realized that these forest types associated with streams and rivers were the least understood and most variable in terms of species composition in the state.

Furthermore, in one of the more detailed early botanical studies of Ohio's regional flora, Griggs (1914) stated no problem was so difficult as the reconstruction of the vegetation of the bottomlands along the large streams and in his words "there is not a vestige left to suggest the original condition of the Hocking bottom between Lancaster and Logan except the swamps and a few large trees standing in the fields into which it has been converted."

The amount and details of specific information on the vegetation-environment relationships of relatively undisturbed vegetation of Ohio's riparian forests are varied and depend largely on the specific eco­region. Overall, there tends to be spe­cific information on the overstory composition, but very little data on the understory and ground-flora plant communities. For example, many of the county-level M.S. theses and OBS and OAES reports tend to be distributed across each ecoregion of the state and describe the composition of local riparian forests (e.g., Diller, 1932; Jones, 1936; Norris, 1948).

Furthermore, Andreas (1989) suggests that riparian plant communities of the glaci­ated Allegheny Plateau ecoregion are related to predictable assemblages of plant communities that are organized on the basis of geology, topography, moisture availability, and aspect. For instance, swamp forests dominated by overstories of red maple (Acer rubrum L.), silver maple (A. saccharinum L.), white ash (Fraxinus americana L.), and American elm (Ulmus americana L.) and understories of common elder­berry (Sambucus canadensis (L.) R. Bolli), beggarticks (Bidens spp.), sedge (Carex spp.), sweet woodreed (Cinna arundinacea L.), Canadian woodnettle (Laportea canadensis (L.) Weddell), rice cutgrass (Leersia oryzoides (L.) Sw.), sensitive fern (Onoclea sensibilis L.), and reed canarygrass (Phalaris arundinacea L.) occur across the eco­region on flat, poorly-drained flood­plains associated with small streams and rivers.

Conversely, on silt-laden deposits of floodplains along major river systems of the ecoregion (e.g., Cuyahoga and Scioto Rivers and Killbuck Creek), boxelder (Acer negundo L.), silver maple (Acer saccharinum), Ohio buckeye (Aesculus glabra Willd.), green ash (Fraxinus pennsylvanica Marsh.), black walnut (Juglans nigra L.), American sycamore (Platanus occidentalis L.), eastern cottonwood (Populus deltoides Bartr. ex Marsh.), and American elm (Ulmus americana) dominate the overstory.

The understory of these floodplains along larger streams and rivers is similar to the swamp forests described previously, with the addition of several species including silver false spleenwort (Deparia acrostichoides (Sw.) M. Kato), eastern bottlebrush grass (Elymus hystrix L. var. hystrix), white­grass (Leersia virginica Willd.), ostrich fern (Matteuccia struthiopteris (L.) Todaro), Virginia creeper (Parthenocissus quinquefolia (L.) Planch.), marshpepper knotweed (Polygonum hydropiper L.), jumpseed (P. virginianum L.), eastern poison ivy (Toxicodendron radicans (L.) Kuntze), cutleaf coneflower (Rudbeckia laciniata L.), wingstem (Verbesina alternifolia (L.) Britt. ex Kearney), and striped cream violet (Viola striata Ait.)

However, these sources of reference vegetation conditions often provide generalizations of the different overstory and understory species, but not the site­specific information needed to develop detailed restoration templates for riparian areas across each ecoregion of the state.

While many of the refereed journal articles that examine the ecology of individual old-growth forests do provide site-specific information on the vegetation-environment relationships of riparian forests, they often focus only on overstory composition and rarely on the structure of these riparian forests (Table 1). Additionally, the information provided by these surveys and studies is often disparate, resulting in considerable gaps in our understanding of the factors that regulate the composition and structure of riparian forests across the ecoregions of Ohio (Table 1). In the sections that follow, we document the available information of reference riparian conditions for each ecoregion from these studies of specific old-growth and mature forests.