Changes in Older and Younger Woods in West-Central Ohio

This study examines changes in two forest stands in the Quercus-Acer saccharum forest region of west central Ohio: an old-growth stand changing from Quercus-dominated to Acer saccharum-dominated and a stand established following agricultural abandonment about 1950. Both stands are in the Wright State University woods. Permanent plots were sampled in 1980 (younger stand only), 1982 (older stand only), 1993, and 2000. The older stand had more small, fewer intermediate, and more large stems than the younger stand. The plot in the new stand showed a bell-shaped distribution with most stems established shortly after land abandonment. Mortality decreased and growth increased with stem size for both stands. Acer saccharum in all sizes and large Quercus dominated the older stand. The younger stand was dominated by Robinia pseudo-acacia with Acer saccharum also important. In the older plots small stems generally were clustered, intermediate-sized stems randomly distributed, and the largest stems regularly distributed. In the younger plot small stems were aggregated while larger ones were randomly distributed. Quercus regenerated well until the late 1800s, singly or in small groups, but few stems have become established since 1900. Quercus may need fires or grazing to regenerate successfully. Both stands are changing to increased dominance by Acer saccharum and other shade-tolerant species as they lose species (Robinia pseudo-acacia in the younger stand, Quercus in the older stand) more successful under past than present conditions. OHIO J SCI 105 (5):116-124, 2005 Manuscript received 1 October 2003 and in revised form 15 March 2005 (#03-15). INTRODUCTION In much of the Midwest the last two centuries of changing land management practices have been characterized partly by a decrease in oaks (Quercus), affecting first their regeneration and later their importance in the canopy (Whitney and Somerlot 1985; Lorimer 1993; Walters and McCarthy 1997; McCarthy and others 2001). Other species, such as sugar maple (Acer saccharum), have waxed as the oaks have waned. This change in species dominance has occurred even in stands which fit many of the definitions of old growth (Runkle 1996), such as no history of large-scale logging and the presence of old trees and both standing and fallen coarse woody debris. Few studies have quantified the rates and directions of changes in those stands. Other understudied aspects of forest dynamics are the speed and direction of changes in mid-successional forests. Ohio has gone from 12% forested in 1940 to 30% forested in 1990 (Griffith and others 1993). Therefore over 18% of the land area of Ohio in 1991 was composed of forests <50 yr old. Understanding the dynamics of those forests is thus important for understanding the natural and economic environment of Ohio, both at present and in the future. One unresolved question is whether changes in older and mid-successional forests are leading to the same or to different types of vegetation in the future. The goals of this study are: 1) to describe the species composition and structure of an old-growth (never clear-cut) woods dominated by sugar maple and oaks sampled in 1982, 1993, and 2000; 2) to describe the species composition and structure of a stand that was released from agriculture about 1950 and sampled in 1980, 1993, and 2000; 3) to document changes in structure in both those stands; 4) to determine changes in species composition of the older stand, especially for oak and maple; 5) to determine the historical pattern of oak regeneration in that stand; and 6) to determine whether the two stands might eventually have similar vegetation if current trends persist.