Claypan 10-12 P.Z.
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1 More details
- Transition T3 More details
- Transition T4 More details
- Restoration pathway R2 More details
- Transition T7 More details
- Transition T5 More details
- Transition T6 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
The Reference State is a representative of the natural range of variability under pristine conditions. State dynamics are maintained by interactions between climatic patterns and disturbance regimes. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Plant community phase changes are primarily driven by fire, periodic drought and/or insect or disease attack. Due to the nature and extent of disturbance in this site, multiple community phases would likely occur in a mosaic across the landscape.
Characteristics and indicators
Low sagebrush is killed by fire and does not sprout (Young 1983). Establishment after fire is from seed, generally blown in and not from the seed bank (Bradley et al. 1992). Fire risk is greatest following a wet, productive year when there is greater production of fine fuels (Beardall and Sylvester 1976). Fire return intervals have been estimated at 100-200 years in black sagebrush (Artemisia nova) dominated sites (Kitchen and McArthur 2007) and likely is similar in the low sagebrush ecosystem; however, historically fires were probably patchy due to the low productivity of these sites.
Submodel
Description
This state is similar to the Reference State 1.0. Ecological function has not changed, however the resiliency of the site has been reduced by the presence of invasive weeds. This state has the same three general community phases. These non-native species can be highly flammable, and promote fire where historically fire had been infrequent. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These feedbacks include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Positive feedbacks decrease ecosystem resilience and stability of the state. These include the non-natives’ high seed output, persistent seed bank, rapid growth rate, ability to cross pollinate, and adaptations for seed dispersal.
Characteristics and indicators
The invasion of sagebrush communities by cheatgrass (Bromus tectorum) has been linked to disturbances (fire, abusive grazing) that have resulted in fluctuations in resources (Chambers et al. 2007). The introduction of annual weedy species, like cheatgrass, may cause an increase in fire frequency and eventually lead to an annual state. Conversely, as fire frequency decreases, sagebrush will increase and with inappropriate grazing management the perennial bunchgrasses and forbs may be reduced.
Submodel
Description
Annual non-natives dominated site productivity and site resources. The dominance of non-natives controls the spatial and temporal distribution of soil moisture, soil nutrients, and energy resources. Remaining patches of sagebrush and/or perennial bunchgrass suffer from increase competition and narrowed fire returned intervals.
Characteristics and indicators
This state experiences frequent fire due to increased cover and continuity of fine fuels. Fire is frequent enough to prevent the recovery of long-lived native perennials like Lahontan sagebrush. Disturbance tolerant shrubs may be present or increasing depending on time since disturbance.
Submodel
Description
Sagebrush cover exceeds site concept and may be decadent, reflecting stand maturity and lack of seedling establishment due to competition with mature plants. The shrub overstory and Sandberg bluegrass understory dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed. Bare ground and soil redistribution may be increasing. Non-natives are stable to increasing.
Submodel
Description
An abiotic threshold has been crossed and state dynamics are driven by fire and time. This state is characterized by the dominance of non-native annuals and active soil redistribution and erosion. Ecological process including hydrology, energy capture and nutrient cycling are spatially and temporally truncated. Shorter fire return intervals, increase in invasive species and poor reproductive potential of remaining natives are feedbacks contributing to the stability of this site.
Characteristics and indicators
The invasion of sagebrush communities by cheatgrass (Bromus tectorum) has been linked to disturbances (fire, abusive grazing) that have resulted in fluctuations in resources (Chambers et al. 2007). The introduction of annual weedy species, like cheatgrass, may cause an increase in fire frequency and eventually lead to an annual state.
Submodel
Mechanism
Trigger: This transition is caused by the introduction of non-native annual plants, such as cheatgrass and mustards.
Slow variables: Over time the annual non-native species will increase within the community.
Threshold: Any amount of introduced non-native species causes an immediate decrease in the resilience of the site. Annual non-native species cannot be easily removed from the system and have the potential to significantly alter disturbance regimes from their historic range of variation.
Mechanism
Trigger: Repeated, widespread and sever fire. Slow Variables: Increase production and cover of non-native annual species over time. Threshold: Loss of deep-rooted perennials bunchgrasses and shrubs truncates, spatially and temporally, nutrient capture and cycling with the community.
Mechanism
Trigger: Prolonged drought coupled with inappropriate grazing grazing management will decrease or eliminate deep-rooted perennial bunchgrasses. Favoring growth and establishment of Sandberg bluegrass and shrubs. Soil disturbing treatments will reduce sagebrush and favor an increase in Sandberg bluegrass.
Slow variables: Long term decrease in deep-rooted perennial grass seed production, reproduction, and density allows for an increase in Sandberg bluegrass and favor shrub growth and establishment.
Threshold: Loss of deep-rooted perennial bunchgrasses changes nutrient cycling, nutrient redistribution, and reduces soil organic matter and infiltration.
Constraints to recovery
Fire or brush treatment may be coupled with inappropriate grazing management.
Mechanism
Seeding with native species followed by prescribe grazing. Minimize soil disturbance and maximize non-native annual plant biomass removal during early spring. Combine prescribe grazing with seeding of native species. Continue to protect site from wildfire. Probability for success extremely low.
Mechanism
Trigger: Inappropriate grazing, wildfire, prolonged droughts, and soil disturbing treatments. Controlling Variables: Excessive grazing will eliminate ground cover that holds soil. Soil disturbing treatment will create soil instability and could create compaction. Wind and precipitation will begin to create rills and gullies along unstable and compacted soils. Threshold: When the soil is disturbed, climatic influences such as precipitation and wind can begin forming gullies and rills.
Mechanism
trigger: Wildfire or shrub eliminating treatments. Controlling Treatments: Wildfire eliminates shrubs and perennial grasses, providing sufficient resources for annuals to dominate the landscape. Threshold: Decreasing shrubs and perennial annuals create opportunities of annuals to populate the landscape. With time, more annuals will be present causing frequent severe wildfires. These conditions will favor annual species due to availability of nutrients, soils, sunlight, and moisture.
Mechanism
Trigger: Inappropriate grazing management following fire, multiple fires, prolonged drought or any combination of these would increase soil erosion. Soil disturbing treatments such as a failed drill seeding could also increase erosion.
Slow variable: Bare ground interspaces large and connected; water flow paths long and continuous, understory is sparse.
Threshold: Soil redistribution and erosion is significant and linked to vegetation mortality evidenced by pedestalling and burying of herbaceous species and / or lack of recruitment in the interspaces.
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.