Abstract Detail



Ecology

Anderson, Roger [1].

Changes in tree species composition, abundance, and diversity in a remnant historic prairie grove in central, Illinois USA over a thirty-four year period (1977-2011).

Historically, fire was an important factor in maintaining oak savannas and open oak woodlands in the Midwest.  However, fire suppression during the past two centuries resulted in Midwest woodlands on mesic upland sites transitioning from dominance by fire-resistant, shade-intolerant oak and hickory species to dominance by fire-sensitive, shade-tolerant mesophytes.  I studied changes in tree species composition and diversity in one of these upland forests, Funks Grove in McLean County, Illinois, over a period of 35 years (1977-2011).  The 13 ha study site currently supports a closed canopy forest dominated by sugar maple (Acer saccharum).  However, in 1977 scattered large (120-180 cm dbh) living and dead open-grown burr oaks (Quercus macrocarpa) provided evidence of a historic open forest.  Government Land Office (GLO) records (1823) indicate oaks dominated the historic vegetation with a combined Importance Value (IV) of 43.2, (for all species combined IV = 100).  Historic tree density was 28 trees/ha compared to current densities of 318 trees/ha.  On my study site in 1977, the dominant tree species was American elm (Ulmus americana) (IV = 29), which experienced a rapid decline (IV = 1.6) by 1984 due to Dutch elm disease, and sugar maple (IV = 46) dominated the forest.  From 1823 to 2011, tree species richness varied from 11 to 8 trees, diversity (Shannon-Wiener Index) declined from 2.30 to 1.37, and evenness decreased from 0.96 to 0.57.  In the past 10-15 years, white-tailed deer (Odocoileus virginianus) browsing diminished seedlings of most tree species, except paw paw, which deer rarely browse.  Aerial deer counts made during the 2007-2008 winter yielded a density of 75 deer km-2 (194 deer/square mile).  Current trajectory of canopy tree recruitment suggests that development of a dense paw paw (Asimina triloba) understory will restrict canopy tree recruitment and diversity.  Deer do not browse paw paw, but they browse sugar maples and other hardwood tree species.  Returning vegetation to historic conditions requires: (1) sugar maple thinning, (2) reducing paw paw and white-tailed deer abundance, and (3) fire management.  Unfortunately, it might be too late to implement this management in Funks Grove effectively.  


1 - Illinois State University, Department Of Biological Sciences, 315 West College Ave, School Of Biological Sciences, Normal, IL, 61790, United States

Keywords:
fire
suppression
forest
deer
browsing.

Presentation Type: Oral Paper
Number:
Abstract ID:174
Candidate for Awards:None


Copyright © 2000-2018, Botanical Society of America. All rights reserved