Natural Resources
Conservation Service
Steep Adobe 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
Dominant plant species
Texas live oak (Quercus fusiformis), tree
Ashe's juniper (Juniperus ashei), tree
Texas wintergrass (Nassella leucotricha), grass
Submodel
Mechanism
Shrubs make up a portion of the plant community in the Savannah State, hence woody propagules are present. Therefore, the Savannah State is always at risk for the transition to the Shrubland State in the absence of fire. The mean fire return interval in the Savannah State is 7-10 years. Even with proper grazing and favorable climate conditions, lack of fire for 20-30 years will allow woody species to increase in canopy to reach the 50% threshold level. Introduction of aggressive woody invader species (i.e. juniper or mesquite) increase the risk and accelerate the rate at which this transition state is likely to occur. This transition can occur from any community within the Savannah State, it is not dependant on degradation of the herbaceous community, but on the lack of some form of brush control. Improper grazing, 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.
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 fire sprouters. Chemical or hand 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, range planting will be necessary to restore a desirable herbaceous plant community. The driver for Restoration Pathway R2A is fire and/or brush control combined with natural restoration of the herbaceous community or active management of the herbaceous restoration process (range seeding). Restoration may require aggressive treatment of invader species.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
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|
Prescribed Burning |
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Prescribed Grazing |
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Range Planting |
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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