Ecological dynamics
The information contained in the State and Transition Diagram (STD) and the Ecological Site Description was developed using archeological and historical data, professional experience, and scientific studies. The information presented is representative of a very complex set of plant communities. Not all scenarios or plants are included. Key indicator plants, animals and ecological processes are described to inform land management decisions.
This site occurs on predominantly clayey, saline alluvial soils. The species occupying this site may vary greatly depending on the salinity. In the reference state, the dominant vegetation will consist of alkali sacaton (Sporobolus airoides) and inland Saltgrass (Distichlis spicata). Other salt tolerant grasses and forbs may also occur on areas of lower salinity.
In many areas, seeds from the honey mesquite tree (Prosopis glandulosa) have been introduced and the trees have begun to invade the site. These trees do well on the fine textured soils and are tolerant of the saline soils. Once the mesquite trees have invaded a site, they may be quite difficult to eradicate.
Some areas of this site have been subjected to sever soil disturbance from either farming practices or construction activities. After such disturbance, these areas may be very slow to revegetate due to the salinity of the soils. This can result in a barren landscape for many years.
State and Transition Diagram:
A State and Transition Diagram for the Saline Bottomland (R078CY046OK) site is depicted below. Thorough descriptions of each state, transition, and pathway follow the model. Experts base this model on available experimental research, field observations, professional consensus, and interpretations. It is likely to change as knowledge increases.
Plant communities will differ across the MLRA because of the natural variability in weather, soils, and aspect. The Reference Plant Community is not necessarily the management goal; other vegetative states may be desired plant communities as long as the Range Health assessments are in the moderate and above category.
The biological processes on this site are complex. Therefore, representative values are presented in a land management context. The species lists are representative and are not botanical descriptions of all species occurring, or potentially occurring, on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the site.
Composition by dry weight and percent canopy cover are provided to describing the functional groups. Most observers find it easier to visualize or estimate percent canopy for woody species (trees and shrubs).
The following diagram suggests some pathways that the vegetation on this site might take. There may be other states not shown on the diagram. This information is intended to show what might happen in a given set of circumstances. It does not mean that this would happen the same way in every instance. Local professional guidance should always be sought before pursuing a treatment scenario.
State 1
Saline Grassland (Reference)
This is the reference or diagnostic community for the site. The description is based on early range site descriptions, clipping data, professional consensus of experienced range specialists, and analysis of field work.
The vegetation of the reference state may be highly variable from site to site depending on the degree of soil salinity. Generally, the site will be dominated by alkali sacaton and inland Saltgrass. Other grasses and forbs may occur depending on the level of salinity in the soil. These other plants may include switchgrass, western wheatgrass, Canada wildrye, and vine mesquite. Forbs may include ragweed, aster, and croton species.
Rangeland aboveground productivity in this state is estimated between 1,500 and 3,000 pounds per acre.
State 2
Mesquite Shrubland
This state is the result of invasion by mesquite trees. Herbaceous production may not be altered drastically as mesquite do not seem to shade out the herbaceous plant as much as other woodies. However, the presence of mesquite may have management implications depending on the land use and density. Control and or eradication of these trees can be costly. Careful consideration of infestation levels and desired management goals should be considered.
State 3
Barren
In some areas, these sites have been cleared or cultivated. Often once the vegetation is removed, it can take a long time to revegetate. These areas become barren and subject to soil movement during heavy rains. Once some plants recover on the site, it may begin to resemble the original state(1). This process may take many years.
Transition T1A
State 1 to 2
Without brush management, mesquite may invade and eventually dominate the site transitioning it to State 2.
Transition T1B
State 1 to 3
If the soils on these sites are disturbed by cultivation or heavy equipment, they may take a very long time to re-vegetate, transitioning the site to State 3.
Transition T2A
State 2 to 3
If the soils on these sites are disturbed by cultivation or heavy equipment, they may take a very long time to re-vegetate, transitioning the site to State 3.
Restoration pathway R3A
State 3 to 1
If there is an available seed source remaining in the soil, the site may recover to State 1. This may take many years.
