Understory response to gaps caused by the death of Ulmus americana in central New York.

Shrub species typical of open habitats were abundant in gaps created by the death of 2 or more neighboring elms (multiple-tree gaps) but not in single-tree gaps. Multiple-tree gaps contained fewer seedlings and saplings of canopy tree species than did single-tree gaps. The patchiness of occurrence of the open-canopy shrubs and their relationship to multiple-tree gaps were not reflected in conventional large-scale (0.1ha) vegetation samples of the same stands. Establishment of dense patches of shrubs may inhibit tree regeneration within the multiple-tree gaps.-from Author