Valley Terrace Group
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1C More details
- Restoration pathway R2A More details
- Transition T2A More details
- Restoration pathway R3A More details
- Restoration pathway R3B 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
This state represents the disturbance regime prior to Euro-American settlement and the absence of invasive plant species. Typical fire return interval is approximately 1 to 10 years.
Submodel
Description
This state results from fire-exclusion with minimal ground disturbance. The impact of invasive species is small.
Submodel
States 1 and 5 (additional transitions)
2.1. Mixed Forest, Deciduous Trees, Conifers, Deciduous Shrubs, and Forbs
2.5. Coniferous Forest, Douglas-fir, Deciduous shrubs, and Forbs
Description
This state represents post-cultivation conditions that may best fit within land-use models in future work. Weedy invasive species are usually present and competitive. Fire is excluded. Hydrology is not altered by draining or filling.
Submodel
Mechanism
T1A:
This pathway represents cessation of fire over a period long enough that grasses and forbs present in the reference community do not recover dominance following removal of woody vegetation. Tree seedlings, including conifers, establish and begin to cast shade, leaf, and needle litter. Soils develop a litter layer. Consequently, forbs shift to mesic, shade-tolerant species (Thilenius, 1964).
T1B:
This pathway is similar to Transition Pathway T1A with additional conditions favoring the development of a pure oak forest stand. Thilenius (1964, 1968) points out from early records that savannas briefly converted to wheat production or cleared for forage were abandoned by the mid-1880’s and “reverted to oak scrub.” Top-growth removal without root destruction promotes sprouting and could have led to dense, monotypic oak forest stands. It is also possible that a cohort of dense oak trees developed from seed once fires ceased. Along this transition pathway, oaks regenerate and begin to cast shade, leaf, and needle litter. Soils develop a litter layer. Consequently, the forb layer succeeds to mesic, shade-tolerant species (Thilenius, 1964).
Mechanism
This pathway represents tree and stump removal and tillage to the extent that root systems and seed banks of native plants are depleted.
Mechanism
R2A:
This pathway represents tree thinning, prescribed fire or mowing, seeding native grass.
R2B:
This pathway represents tree thinning (or oak renewal by cutting and leaving stumps intact), prescribed fire or mowing, seeding native grass, and weed control.
Mechanism
This pathway represents tree and stump removal and tillage to the extent that root systems and seed banks of native plants are depleted. Soil litter layer is removed.
Mechanism
This pathway represents controlling weeds, seeding native grasses, replanting savanna trees, and prescribed fire or mowing.
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.