Group selection silviculture creates canopy openings that can alter connectivity in patchy forests, thereby affecting wildlife movement and fire behavior. We examined effects of group selection silviculture on percolation (presence of continuously forested routes across a landscape) in Sierra Nevada East-side pine forest in northern California, USA. Four * 250 ha project areas were analyzed at three map resolutions in three ways: analyzing forest cover maps for percolation before and after

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... -selection treatment, placing simulated group openings in forest cover maps until fragmentation occurred, and comparing project areas to neutral maps that varied in forest cover and self-adjacency. Two project areas were fragmented (i.e., did not percolate) prior to treatment, one resisted fragmentation, and the other became fragmented by treatment when analyzed at 30 m cell resolution. Median simulated openings required to create fragmentation agreed well with the actual number. There was a well-defined transition between percolating and non-percolating neutral maps; increased aggregation of forest lowered the critical value at which forests percolated. A logistic model based on these maps predicted percolation behavior of the project areas effectively, but alternative generating algorithms gave slightly different predictions. A graph of this model provides a straightforward way to visualize how close a landscape is to fragmentation based on its forest cover and aggregation. In East-side Sierran landscape, fragmentation from group-selection openings may make the landscape less hospitable to the American marten but more resistant to crown fire.