Riparian Subirrigated (RSb) LRU 01 Subset Y
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1B More details
- Transition T1C More details
- Transition T1D More details
- Restoration pathway R2A More details
- Transition T2A More details
- Restoration pathway R3A More details
- Transition T3A More details
- Transition T3B More details
- Restoration pathway R4 More details
- Transition T4A 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) is defined by a high diversity of plants in the floodplain of an active riparian area. This state consists of three potential communities: the Salix Community (1.1), the Colonizer Community (1.2), and the Mid-Statured Tree Community (1.3). All communities tend to contain high amounts of willow species, grasses, sedges, and rushes. This ecological site is not forested, and tree cover by cottonwoods (Populus spp.) is restricted to small stands of only a few trees.
Due to the extreme variability and dynamics of this ecological site, it is common for multiple communities to exist within a relatively small area. The Salix Community (1.1) would be most common and stable throughout the MLRA. The Salix Community (1.1) is considered the reference plant community for this State.
Submodel
Description
Mature Tree State (2) consists of one community. This state exists primarily in response to man-made control structures removing hydrology and/or as stream or river downcuts in the current channel. A large cottonwood gallery exists in dry condition. This state exists primarily on larger watersheds but can exist on smaller stream systems.
Submodel
Description
This state contains a single plant community dominated by increaser plants. This state exists in response to unmanaged grazing.
Submodel
Description
The Dry Riparian State is a site dominated by native grasses and dry shrubs as a result of loss of hydrology due to downcutting of streams or stream meandering.
Basin wildrye and tufted hairgrass are dominant herbaceous species. Transitions exist between the Salix Community (1.1) and the Colonizer Community (1.2). Many small riparian systems are not suited for tree growth; as a result, this differs from the Mature Tree State (2).
Submodel
Description
The Invaded State (5) includes many non-native species that have come to dominate riparian areas. Some species may include: orchard grass, timothy, Kentucky bluegrass, non-native thistles, Russian olive, leafy spurge, spotted knapweed, houndstounge, foxtail barley, and whitetop mustard. Often, sites are a combination of pasture grasses and invading weeds. The site is considered to be in a terminal state, meaning these sites are likely to never return to Reference, regardless of management.
Submodel
Mechanism
Typically, the progression to this state is a long, linear process in which the Salix Community (1.1) transitions to the Mid-Statured Tree Community (1.3), given time and the loss of hydrology due to stream downcutting or the implementation of water control structures. Lack of flooding has created a very stable community.
Mechanism
Improper grazing changes the plant community to a shorter grass and grasslike community. This affects site stability and hydrology (reduced infiltration and increased runoff). Soil compaction may also be present if alluvium is of fine particle size.
Mechanism
Natural stream dynamics create a dry site that was once wetter. Improper grazing creates accelerated stream downcutting and bank erosion.
Mechanism
Sites are invaded by noxious weeds or introduced pasture grasses. Pasture grasses may be planted or a result of invasion from neighboring sites. Improper grazing may be a trigger for invasion, but flooding may transport seeds to freshly deposited alluvium.
Mechanism
The site experiences a catastrophic flooding event often associated with extreme weather events and/or ice jams.
Mechanism
Sites are invaded by noxious weeds or introduced pasture grasses. Pasture grasses may be planted or a result of invasion from neighboring sites. Improper grazing may be a trigger for invasion, but flooding may transport seeds to freshly deposited alluvium.
Mechanism
Improved grazing practices (change of season of use, conservative stocking rates), tree and shrub establishment, and water impoundments (beaver dams, log jams, or dam analogs). The Bureau of Land Management Dillon Field Office is experimenting with methods of restoring hummocked sites by crushing the hummocks with an excavator during the dry period in the summer. The results have not yet been evaluated.
Mechanism
Drying of the system as a result of loss of hydrology and an increase in drier shrub species encroaching.
Mechanism
Sites are invaded by noxious weeds or introduced pasture grasses. Pasture grasses may be planted or a result of invasion from neighboring sites. Improper grazing may be a trigger for invasion, but flooding may transport seeds to freshly deposited alluvium.
Mechanism
Grazing management (timing and amount to improve shrub and tree establishment), brush management to remove unwanted dry species. As stream dynamics return, the increased soil moisture will allow wetland species to return over time.
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.