Dunn, Christopher P.

Shrub layer response to death of Ulmus americana in southeastern Wisconsin lowland forests

Date created
The relationship of the shrub layer to soil factors (K, pH, P, Mg) and to death of canopy elms was studied on a stand basis in 15 southern Wisconsin lowland forests. Ordination and correlation analysis revealed a positive relationship of shrub layer species composition to soil K, but not to pH, P, or Mg. Rank correlation of species composition to density of dead elm was not significant. Total shrub density, however, did show a relationship to dead elm density. When dead elm density was greater than 5 stems/ha, shrub density increased significantly and predictably. If the density of dead elm/ha is lower than this critical density, no community (i.e., whole stand) response can be detected and shrub response is essentially a small gap phenomenon. Above this critical density, shrub density increases significantly as the number of dead elms increases, resulting in a transition from small gap processes to a more general openness. That is, as the number of dead trees/ha increases, the gap effect widens and gaps begin to coalesce
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Volume, Page Number
113, 142-148