Natural Resources
Conservation Service
CLAYPAN SOUTH 8-12 PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T2A More details
- Transition T2B More details
- Transition T3A More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State 1.0 is a representative of the natural range of variability under pre- Euro settlement conditions. State dynamics are maintained by interactions between climatic patterns and disturbance regimes. Plant community phase changes are primarily driven by fire, periodic drought and/or insect or disease attack. Management should focus on maintaining high species diversity of desired species to promote site resiliency.
Characteristics and indicators
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.
Resilience management
Maintaining high species diversity, including native grasses, forbs and shrubs, to promote site resiliency.
Dominant plant species
little sagebrush (Artemisia arbuscula), shrub
Thurber's needlegrass (Achnatherum thurberianum), grass
bluebunch wheatgrass (Pseudoroegneria spicata), grass
Submodel
Description
This state is similar to the Reference State 1.0. Ecological function has not changed, however the resiliency of the state has been reduced by the presence of non-native annuals. These non-native species can be highly flammable, and promote fire where historically fire had been infrequent.
Characteristics and indicators
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.
Resilience management
Maintain high diversity of desired species to promote organic matter inputs and prevent the dispersal and seed production of the non-native invasive species.
Dominant plant species
little sagebrush (Artemisia arbuscula), shrub
bluebunch wheatgrass (Pseudoroegneria spicata), grass
Thurber's needlegrass (Achnatherum thurberianum), grass
Submodel
Description
This state is the result of many years of inappropriate grazing management during time periods harmful to perennial bunchgrasses. Low sagebrush dominates the overstory and rabbitbrush may be a significant component. Understory is dominated by shallow-rooted perennial bunchgrass, like Sandberg bluegrass, which has replaced a more diverse community of deep-rooted perennial bunchgrasses. Sagebrush cover is stable and may be decadent, reflecting stand maturity and lack of seedling establishment due to competition with mature plants. Annual non-natives are typically present, but do not control site resources.
Characteristics and indicators
Sandberg bluegrass has increased, replacing deep-rooted perennial bunchgrasses as the dominant grasses. The shrub overstory and bluegrass understory dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed.
Dominant plant species
little sagebrush (Artemisia arbuscula), shrub
Sandberg bluegrass (Poa secunda), grass
cheatgrass (Bromus tectorum), grass
Submodel
Description
This state has crossed a biotic threshold (dominated by non-native annuals) and an abiotic threshold (site dynamics are driven by fire and time).
Characteristics and indicators
Herbaceous understory is dominated by annual non-natives. The site is no longer resistant or resilient following disturbance. The annual or semi-annual fire return interval establishment of cheatgrass with a minor component of sprouting shrubs. This shortened fire return interval prevents the establishment and survival of long lived native perennials preventing this site from experiencing natural recovery.
Dominant plant species
cheatgrass (Bromus tectorum), grass
medusahead (Taeniatherum caput-medusae), grass
tall tumblemustard (Sisymbrium altissimum), grass
Submodel
Mechanism
Trigger: introduction of non-native annual plants, such as cheatgrass, medusahead, mustards, and bur buttercup. Slow variables: over time annual non-native plants increase within the plant community, competing with native perennials for limited moisture, light and nutrient resources.
Constraints to recovery
Any amount of non-native annuals cause an immediate reduction in site resilience. Annuals have the potential to significantly alter disturbance return intervals from their historic range of variation. Annual non-native species cannot be easily removed from the system.
Mechanism
Trigger: Severe fire in community phase 2.3 eliminates sagebrush overstory, may damage deep-rooted bunchgrasses limiting their recovery, and enhance Sandberg bluegrass and annual non-natives. Slow variable: Long-term decrease in deep-rooted perennial grass density. Inappropriate grazing management, drought or both contribute to dominance shallow-rooted bunches and annual non-natives.
Constraints to recovery
Loss of deep-rooted perennial bunchgrasses changes nutrient cycling and redistribution, soil moisture storage and reduces organic matter, further reducing resilience of the site
Mechanism
Trigger: fire(s) and/or soil disturbing management actions damage existing herbaceous component, reducing site resistance to dominance by annual non-natives. Slow variables: Increased production and cover of non-native annual species, which may be coupled with additional stressors like heavy grazing pressure and/or drought.
Constraints to recovery
Threshold: changes in the dominant functional/structural groups (biotic threshold) changes the size, intensity and spatial variability of fire (biotic threshold).
Mechanism
Trigger: Fire(s) and/or soil disturbing management practices damage existing grass community reducing site resilience and resistance. Slow variables: Prolific seed production by annual non-natives increase competition with native perennials during times when soil moisture is critical for germination and establishment.
Constraints to recovery
Increased, continuous fine fuels change the frequency, intensity and spatial variability of fire. Changes in the dominant structural/functional groups result in changes to energy capture and nutrient cycling limiting the sites ability to recover naturally.
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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