Loess High Terrace Savanna

Description

As an oak savanna, this state has a reference plant community which is categorized as savanna and includes grasses, forbs, scattered oak grubs, and clumps of shrubs. Periods of 10 to 20 years with no fire and no grazing can cause this state to shift into an Oak Open Woodland.

Conversely, Grazing and browsing accompanied by fire intervals of 1 to 3 years will shift this phase back towards the reference community. Fire suppression greater than 20 years will cause this state to shift to an Oak Woodland. Restoration to the reference state is possible through removal of woody species and prescribed fires every 1-3 years. Conversion to cropland, or pasture are also typical transitions from reference state, the transition to cropland involves tillage and a conventional cropping system, and the transition to pasture is similar, requiring tillage, vegetative seeding, and grassland management.

Submodel

Description

This oak woodland forms as a result of a fire suppression interval of greater than 20 years on the reference state. The woody species have invaded enough to cause significant canopy closure. Restoration to the reference state requires removal of the woody species and a prescribed fire interval of 1 to 3 years. Two transitions to other states are also possible. The transition to a cool season pasture state is accomplished through woody species removal, tillage, vegetative seeding and grassland management processes. The cropland state is the other possibility, requiring woody removal, tillage, and a conventional cropping system (Woodland Health, 2004).

Submodel

Description

This state is formed from a native reference state, Fire suppressed woodland, or cropland which has been transformed into a cool season pasture due to several processes. In order to transform a native reference state, it requires tillage, vegetative seeding, and grassland management. From a fire suppressed woodland, in addition to those processes involved in the reference state transition, it also requires woody removal. The Cropland transition to this state can be accomplished by only vegetative seeding and grassland management. Conversely, a transition to a cropland state from this state requires tillage and a conventional cropping system. This state can also transition to a native warm season grassland state by vegetative seeding, prescribed fire and grassland management processes.

Submodel

Description

In this state, tillage, seeding and herbicide has destroyed all of the original savanna. All other states can transition to this state through a combination of woody removal, if necessary, along with tillage, and a conventional tillage cropping system. Corn and soybeans are the principal crops. Variation in management within this state creates a wide range of soil properties and can be detrimental to the environment. Transitions to either a cool season pasture or a native warm season grassland are possible. The transition to cool season pasture state requires vegetative seeding and grassland management. The native warm season grassland state can be accomplished by vegetative seeding, prescribed fire and grassland management.

Submodel

Description

The native warm season grassland state is a result of a transition from either a cool season pasture or cropland. Both require vegetative seeding, prescribed fire, and grassland management. It is possible to restore this state to the reference state by vegetative seeding, prescribed fire interval of 1 to 3 years, tree planting and a long rotation.

Submodel