Natural Resources
Conservation Service
Steep Rocky 30-38" PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Restoration pathway R2A More details
-
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
State 1
Savannah State - Reference
Savannah State - Reference
Dominant plant species
Texas live oak (Quercus fusiformis), tree
little bluestem (Schizachyrium scoparium), grass
Submodel
State 2
Shrubland State
Shrubland State
Dominant plant species
Texas live oak (Quercus fusiformis), tree
Ashe's juniper (Juniperus ashei), tree
Texas wintergrass (Nassella leucotricha), grass
Submodel
Mechanism
While the Savannah State has some resistance to shrub dominance, long-term lack of fire or brush control will 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 Savannah State is 5-10 years. Even with proper grazing management and favorable climate conditions, lack of fire for 15-25 years will allow woody species to increase in canopy to reach the 60% threshold level. An infusion of invasive 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 5% species composition. This transition can occur from any of the Grassland State Communities. The driver for Transition T1A is lack of fire and/or brush control. The Grassland State is always at risk for this transition because woody species are present in the grassland 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.
Mechanism
Restoration of the Shrubland State to the Savannah State requires substantial energy input. Mechanical or herbicidal brush control treatments can be used to remove woody species. A long-term prescribed fire program may sufficiently reduce brush density to a level below the threshold of the Savannah State, particularly if the woody component is dominated by species that are not re- sprouters. Brush control in combination with prescribed fire, proper grazing, and favorable growing conditions may be the most economical means of creating and maintaining the desired plant community. If remnant populations of tallgrasses, midgrasses, and desirable forbs are not present at sufficient levels, propagules from adjacent sites are frequently necessary to restore reference community species. Range planting will be limited to hand or ATV broadcasting due to the steepness and rockiness of the site. The driver for Restoration Pathway R2A is fire and/or brush control combined with restoration of the herbaceous community and proper grazing management. Restoration may require aggressive treatment of invader species.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Prescribed Grazing |
Model keys
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Ecological sites
Major Land Resource Areas
The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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