The Successional Status of a Southern Wisconsin Oak Woods

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Abstract
We examined the applicability of concepts of succession to 27 yr of tree growth and demographic data from an oak woods. From 1956 to 1983 tree population dynamics in Noe Woods, a black oak—white oak woods in southern Wisconsin, were heavily influenced by oak wilt disease. Between 15 and 20% of the black oaks, many of them large, died in each 5—yr period; much of this mortality was due to wilt. White oak increased in basal area but declined slowly in numbers. Regeneration was dominated by black cherry, boxelder, and American elm; these species are either short—lived and small—statured or threatened by disease, and are, the therefore, unlikely to form a new canopy. None of the species in the woods seems capable of filling the role of a self—replacing climax species in the classical sense. We hypothesize that the absence of a climax species in Noe Woods and other areas of the prairie—forest transition is due to the changed disturbance regime. Decreased fire frequency has created an unprecedented opportunity for shade—tolerant species in dry woods. This opportunity has apparently been met by expansion of shade—tolerant native species from other habitats, invasion of exotic species, and increased abundance of some short—lived and small—statured native species.