Very Rarely To Rarely Flooded Thermic Ephemeral Stream
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition 1 More details
- Transition 2a More details
- Restoration pathway R3a More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
State 1 represents the historic-natural condition for this ecological site. This state no longer exists due to the ubiquitous naturalization of non-native species in the Mojave Desert. If we were to include dynamics for this state it would be the same as displayed in State 2. The presence of non-native species is significant in State 2, but has not yet altered the hydrology or fire frequency.
Historically, stand-replacing fire was probably very rare in this ecological site due to the absence of non-native grasses to fuel fires (Sawyer et al. 2009). When fire did occur, it was probably low severity surface fire that promoted regeneration of short-lived species (Sawyer et al. 2009).
State 2
Reference State
Description
This state represents the most common and most ecologically intact condition for this ecological site at the present time.
Submodel
Description
This state develops when the fire return interval is less than 20 years. This state has been significantly altered from the natural range of variability found in States 1 and 2. Frequent fire intervals favor the non-native annual grasses, and reduce the cover and regeneration of longer lived shrubs, which need more time to reestablish after fire. Competition with non-native grasses for water, nutrients and sunlight reduces seedling survival of native species. Data was not collected for this state, it is based on literature review and the observation that the high cover of non-native grasses present in extensive areas of this site create a high risk for a conversion to a grass-fire cycle.
Submodel
Mechanism
This transition occurs with the introduction of non-native species. Cheatgrass and red brome were most likely introduced into this area in the late 19th century, during active mining and grazing activities. The introduction of non-native species was localized at first, and may have been kept from spreading by a mid-century dry spell. Since the 1970's precipitation has increased and these annual grasses have been spreading to new areas and increasing in cover and density (Salo, 2005, Brooks et. al., 2003).
Mechanism
This transition occurs when the fire return interval is less than 20 years.
Mechanism
Restoration of communities severely altered by repeat fire at the landscape scale is difficult. Methods may include aerial seeding of early native colonizers such desert globemallow and burrobrush. Increased native cover may help to reduce non-native plant invasion, helps to stabilize soils, provides a source of food and cover for wildlife, including desert tortoise (Gopherus agassizii), and provides microsites that facilitate creosote bush establishment. However, the amount of seed required for success is often prohibitive. Large-scale planting of both early colonizers and community dominants tends to be more successful in terms of plant survival, especially if outplants receive supplemental watering during the first two years. Creosote bush and burrobush can be successfully propagated and outplanted. Pre-emergent herbicides (Plateau) have been used in the year immediately post-fire to attempt to inhibit or reduce brome invasion. How successful this is on a landscape scale, and the non-target effects have not yet been determined.
Model keys
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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.