Natural Resources
Conservation Service
Mountain Riparian Forest (PIEN/ALIN)
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Exotic plant invasion
More details -
Transition T2A
Hydrologic alteration
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Restoration pathway R3A
Restoration of hydrologic/biotic processes
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
This represents the historical reference state in pristine conditions. Variability in depth to water table and seasonal fluctuations support native obligate wetland vegetation and vegetated communities include all historical functional and structural groups. The historical disturbance regime is intact and driven primarily by climate which influences drought and flood cycles. The resilience and resistance of the site is bolstered by negative feedbacks between vegetation establishment and hydrologic processes that maintains a dynamic equilibrium with geomorphological processes.
Dominant plant species
Engelmann spruce (Picea engelmannii), tree
gray alder (Alnus incana), shrub
redosier dogwood (Cornus sericea), shrub
currant (Ribes), shrub
Submodel
Description
This state is similar to the reference state yet plant communities include a component of non-native species such as Kentucky bluegrass (Poa pratensis). Community phases and pathways will mirror those of the reference state, yet succession of herbaceous species may be somewhat altered. Ecological process and function have not been altered fundamentally by this low level of invasion, yet resistance and resilience to further disturbance are decreased. Erosion processes are still within a historical range of variation, yet with continued vegetation loss the site risks a transition to an alternative state. Variability in depth to water table and seasonal fluctuations support native vegetation and vegetated communities include all historical functional and structural groups, yet composition and richness may be reduced. The resilience and resistance of the site is bolstered by negative feedbacks between vegetation establishment and hydrologic processes that maintains a dynamic equilibrium with geomorphological processes. This state is common due to widespread invasion of non-native species in the Western US. This state may also include scenarios where an entrenched, confined floodplain has developed following restoration of an incised reach.
Dominant plant species
Engelmann spruce (Picea engelmannii), tree
gray alder (Alnus incana), shrub
redosier dogwood (Cornus sericea), shrub
currant (Ribes), shrub
Kentucky bluegrass (Poa pratensis), grass
Submodel
Description
Since this site is hydrologically dependent on a stream network, sustained disturbance may lead to unstable stream banks and entrenched channels. Removal of woody debris may destabilize banks, decrease hyporheic flow and increase energy during peak discharge and flood events. Road construction may confine floodplains, or concentrate flows, increasing erosion, gradient and discharge, and accelerate downcutting processes. Primary floodplains will become disconnected from the channel and evolve into terraces with significantly lowered water tables. This will often lead to the replacement of obligate wetland plants with facultative wetland plants. Dominant conifer species may shift toward a higher composition of grand fir as water tables are lowered and conditions favor its growth. Herb and shrub plant communities within this state will vary and may depend on water table levels, past disturbance history, drought and current management.
Dominant plant species
grand fir (Abies grandis), tree
Kentucky bluegrass (Poa pratensis), grass
Submodel
Mechanism
Invasion of Kentucky bluegrass and/or other non-native plant species into the site.
Mechanism
This transition may be the result of several disturbances that lower water tables beyond depths that support obligate wetland vegetation, alter sediment supply and transport leading to scouring and channel incision, or directly increase flow velocities or flashiness. These may include: removal of large woody debris or large woody debris sources, from channels or adjacent forests; road construction across or parallel to stream courses; and significant alterations of upland watershed vegetation altering peak discharge or sediment loads.
Mechanism
Restoration of hydrologic and biotic process and function through rehabilitation of channel and vegetation structure may be possible but will require considerable inputs, time and cost. This may require replanting of native vegetation in addition to more intensive action such as the placement of large woody debris; removal of impoundments; road removal or relocation; and mechanical manipulation of stream channel courses among other intensive interventions. Restoration options will be highly site specific and may not be possible/practical in many circumstances. Given time, if channel disturbances are removed and natural channel evolution processes are allowed to take place, the stream will form an entrenched floodplain at a lower depth than the original. The original floodplain will remain a low terrace, perched above the newly forming floodplain and supporting a lowered water table and facultative wetland plant species. The resulting riparian area will be more confined and of significantly less extent than originally. The capacity of the basin to capture and regulate water will be reduced considerably.
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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