Fig. 3. Before and after photographs of permanent vegetation monitoring plot 137 at Necedah National Wildlife Refuge illustrating the use of the structural manipulation model. Pretreatment conditions in 1994 (A) represent typical degraded oak barrens that have converted to even-aged oak woodland. Post-treatment conditions in 1999 (B) show that, although the plot is now structurally more consistent with the savanna concept, the responses expected based on the results of previous studies are lacking. Domination by Carex pensylvanica can be seen in B.