Northern Chalky Ridge

Mechanism

While the Tallgrass/Midgrass Prairie State has some resistance to shrub dominance, long-term lack of fire or brush management may allow brush to dominate the site even under proper grazing management. Shrubs make up a portion of the plant community in this state, therefore propagules are present. The mean fire return interval to maintain the Tallgrass/Midgrass Prairie State is 5 to 10 years. Even with proper grazing management and favorable climate conditions, lack of fire for 15 to 25 years will allow woody species to increase in canopy to reach the 25 percent threshold level. An infusion of invasive woody species (i.e. juniper or mesquite) will speed up the process. Improper grazing management, prolonged drought, and a warming climate will provide a competitive advantage to shrubs which will accelerate this process. Tallgrasses will decrease to less than 10 percent species composition.

The driver for Transition T1A is lack of fire and/or brush control. The Tallgrass/Midgrass Prairie State is always at risk for the transition to the Shrubland State because woody species are present in the prairie plant community. Introduction of aggressive woody invader species (i.e. juniper) increase the risk that this state transition will occur and accelerate the rate at which it is likely to occur.