Canopy and Understory Composition of Old-Growth Riparian Forest in Zoar Valley, NewYork, USA
Thomas P. Diggins
Bruce Kershner
Previous qualitative surveys have suggested the Zoar Valley Canyon of western New York State contains a diverse tract of eastern old-growth forest. In this first quantitative study of the site, we surveyed canopy trees >20 cm diameter at breast height (dbh) in twenty-three 30-m x 30-m quadrats on five prominent streamside terraces. We also catalogued understory trees 1-20 cm dbh in 10-m x 10-m quadrats located within the 30-m x 30-m plots. Nineteen broadleaf and two coniferous species exceeded 20 cm dbh and formed a multi-layered canopy. Four more broadleaf species occurred only in the understory. Thirteen species reached 80-126 cm dbh. Sugar maple (Acer saccharum Marsh.) accounted for 27.3% of canopy basal area and dominated the understory. Size distributions of all trees pooled and, of shade-tolerant species individually, were uneven and negatively logarithmic. In contrast, shade-intolerant species occurred mostly in >40 cm dbh classes and were rare in the understory. Fourteen species reached 35.0-47.5 m in height in this tallest broadleaf forest yet described in the northeastern United States. Increment cores from seven canopy species revealed ages of 170 to 305 years. The study area meets all objective criteria for eastern old growth.
Changes in Presettlement Forest Composition for Five Areas in the Central Hardwood Forest, 1784-1990
James S. Rentch
Ray R. Hicks, Jr.
Witness tree tallies from early land surveys show that presettlement forests in eastern Ohio, southwestern Pennsylvania, and north central West Virginia were oak-dominated forests. Quercus alba was dominant by a large margin – at minimum, twice as abundant as Q. velutina, the second ranked species. Acer saccharum and Fagus grandifolia were among the top ten ranked species at each site; however, their importance value was consistently less than one-third the value for Q. alba. Quercus rubra, Q. prinus, Castanea dentata, and A. rubrum were relatively minor components of presettlement forests, rarely ranked among the 10 most abundant tree species. Where diameter-distribution data were available, results show that oaks were well distributed among all but the smallest size classes, suggesting that oak replacement was a stable feature of these forests. Multiple response permutation procedure-analysis of presettlement and modern U.S. Forest Service Forest Inventory analysis (FIA) data shows a clear separation by historical period. Modern inventories consistently show a significant decline in Q. alba abundance and a large increase for A. rubrum. Other early successional species such as Prunus serotina,Liriodendron tulipifera, and Fraxinus americana showed large increases, although this trend varied somewhat among the sites studied. The species composition of presettlement forests suggests a highly variable disturbance regime in which a variety of species with different life history strategies, disturbance tolerances, and growth requirements shared overstory position. Changes in species dominance over the time period reviewed suggest that 20th century reduction in fire frequency resulted in reduced oak abundance and accelerated recruitment of fire intolerant species.