Loamy Calcareous Pinedale Plateau (LyCa PP)
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition 1-2 More details
- Transition 1-3 More details
- Transition 1-4 More details
- Transition 1-5 More details
- Restoration pathway 2-1 More details
- Transition 2-3 More details
- Transition 2-4 More details
- Transition 2-5 More details
- Restoration pathway 3-2 More details
- Transition 3-4 More details
- Transition 3-5 More details
- Transition 4-5 More details
- Restoration pathway 5-2 More details
- Restoration pathway 5-3 More details
- Restoration pathway 5-4 More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Loamy Calcareous site potential is slightly less than the Loamy site in this LRU, due to the restrictive nature of the shallow calcic horizon that occurs in it. The Big Sagebrush/Bunchgrass Plant Community is well adapted to Cool Central Desertic Basins and Plateaus climatic conditions. The diversity in plant species allows for drought tolerance, and natural plant mortality is very low. These plants have strong, healthy root systems that allow production to increase significantly with favorable moisture conditions.
Plant litter is available for soil building and moisture retention. Plant litter is properly distributed with very little movement off-site.
This plant community provides for soil stability and a properly functioning hydrologic cycle. The soils associated with this site are fertile and hold moderately large amounts of soil moisture, providing a very favorable soil-water-plant relationship until reaching the limiting calcic layer.
The plant community phases can occur homogeneously across a landscape, but more often in the reference state occurred in a mosaic pattern as a result of many small disturbances (Bukowski & Baker, 2013).
Submodel
Description
The Grazing Resistant State is characterized by an herbaceous component dominated by thickspike wheatgrass and Sandberg bluegrass, with limited mid-stature bunchgrasses. Once mid stature bunchgrasses become scarce, it is unlikely there will be sufficient reproductive capability (seed source, tillering, or resprouting) to recover dominance in a reasonable time frame without extra energy being added to the system (Cagney, et al., 2010). The plant community is highly resistant to changes in composition, due to the dominance and competition of established grazing resistant species. However, the community can be restored to the Reference State over time with sagebrush treatments (chemical, mechanical, or biological brush management) and grazing deferment followed by a grazing system that allows periodic rest during the critical growth period. Seeding maybe needed in some instances to achieve desired results.
Submodel
Description
This state contains one community, the Big Sagebrush/Bare Ground Community (3.1). It is characterized by sparse herbaceous plant cover dominated by big sagebrush and bare ground.
Communities in the Bare Ground State (3) have crossed a threshold because of soil erosion, loss of soil fertility, and/or degradation of soil properties. Soil erosion affects the hydrology, soil chemistry, soil microorganisms, and soil physics to the point where intensive restoration is required to restore the site to another state or community. Simply changing grazing management may not create sufficient change to restore the site within a reasonable period. It will require a considerable input of energy to move the site back to the Reference State (1).
The Bare Ground State (3) is at risk of weed invasion due to the high percentage of bare ground, but climatic conditions contribute to higher resistance to invasion. This State is at risk of transitioning to the Disturbed State (4) if mechanical treatments are applied without consideration for seeding or grazing management.
Submodel
Description
This state contains one plant community, the Rabbitbrush/Rhizomatous wheatgrass plant community. It is characterized by rabbitbrush dominance and a perpetual state of disturbance as evidenced in pasture corners, gravel pits and areas repeatedly treated to kill sagebrush.
Submodel
Mechanism
The drivers for transition from the Reference State to the Grazing Resistant State are continuous low intensity spring grazing and/or severe drought.
Continuous spring grazing and/or drought can lead to a decline in palatable mid-stature bunchgrasses. Indian ricegrass, a short-lived perennial that requires more frequent seed production to provide an adequate seedbank, and bluebunch wheatgrass, a long-lived perennial that has elevated growth points, are typically the first species to decline (Natural Resouces Conservation Service, 2007). Needleandthread as well as Letterman’s needlegrass are more grazing tolerant, but will eventually decline in plant density and vigor. As bunchgrasses diminish or die during periods of stress, low- stature bunchgrasses and rhizomatous grasses gain a competitive advantage, creating a shift in species composition towards less productive, shorter species. While bare ground may not change, the pattern of bare ground will shift to larger gaps in the canopy and fewer herbaceous plants between shrubs. Many of the remaining desirable bunchgrasses will be only found in the understory of the sagebrush canopy.
Once mid-stature bunchgrasses species become scarce, it is unlikely that they have sufficient reproductive capability (seed source, tillering, or resprouting) to recover dominance in a reasonable time frame without management changes and extra energy being added to the system (Cagney, et al., 2010). When the understory vegetation has been degraded to this point, the transition to the Grazing Resistant State (2) can occur from either the Bunchgrass/Big Sagebrush Plant Community (1.2) or the Big Sagebrush/Bunchgrass Plant Community (1.1). The transition is not dependent on the increase of shrub cover, but rather the lack of mid-stature bunchgrasses in the canopy interspaces.
Management should focus on grazing management strategies that will prevent further degradation. This can be achieved through a grazing management scheme that varies the season of use to provide periodic deferment during the critical growth period (roughly May-June). Forage quantity and/or quality in the Grazing Resistant State (2) may be substantially reduced compared to the Reference State, and will dramatically fluctuate in the dry vs. wet years.
Mechanism
The driver for transition from the Reference State to the Bare Ground State is continuous high intensity/long duration grazing. Drought can accelerate this transition.
Indicators of this transition include significant declines in herbaceous cover or total annual aboveground biomass production falls below 300 pounds per acre. The trigger for this transition is the loss of understory, which creates open spots with bare soil between the sagebrush canopy (>6 foot gap size). Soil erosion is accompanied by decreased soil fertility driving the transitions to the Bare Ground State. Several other key factors signal the approach of a threshold: an increase in soil physical crusting, a decrease in soil surface aggregate stability, and/or evidence of erosion, including water flow patterns, development of plant pedestals, and litter movement.
Mechanism
The driver for transition from Reference State to the Disturbed State is an increase in the disturbance cycle (i.e. grazing, drought, fire, mechanical, chemical or biological treatments) often in combination with grazing management that does not provide periodic deferment during the critical growth period.
The Reference State (1) may transition to the Disturbed State (4) if multiple soil disturbing activities occur over a relative short time period, effectively decreasing the disturbance return interval. Indicators include an increase in rabbitbrush to dominant levels due to ground disturbance that could be either natural (i.e. water movement) or manmade (i.e. high density/high frequency stocking, mechanical treatments or heavy equipment operations). To prevent this transition, the site will require proper reclamation using the most current science and technology available to restore native vegetation. In some instances, it may not be possible to prevent this transition. In cases where total topsoil loss occurs, it may be impossible to prevent this transition.
Long-term stressors on native species (e.g., improper grazing management, and drought) will alter plant community composition and production over time and may hasten a transition to the Disturbed State (4), but the main trigger is ground disturbance. The resulting lower biomass production, reduced litter, and increased bare ground in this community can promote invasion of undesirable species, but climate and soil chemistry contribute to the resistance of this site to invasives. The site transitions to the Disturbed State when populations of invasive species reach critical levels.
Mechanism
The driver for transition from the Reference State to the Highly Disturbed State (T1-5) is a topsoil removing event with mechanical equipment. Examples include construction sites, oil and gas activity, and borrow areas.
Mechanism
The drivers for this restoration pathway are restoration of native herbaceous species by mechanical or chemical treatment of sagebrush (from community phase 2.1), and grazing rest or deferment followed by changing the season of use from spring to fall. If some mid- stature bunchgrasses remain under the sage canopy, proper grazing management can move the site back to the Reference State (1) when combined with a well-planned mechanical or chemical sagebrush treatment. This could take multiple generations of management or could be accelerated with rest or deferment combined with successive wet springs conducive to seed germination and seedling establishment. (Derner, Schuman, Follett, & Vance, 2014).
Mechanism
The driver for transition from the Grazing Resistant State to the Bare Ground State (T2-3) is continuous high intensity grazing from the Big Sagebrush/Thickspike Wheatgrass Community (2.1). Examples include calving pastures and small acreage horse pastures where rotational grazing is not employed, and stocking densities are high. Extended drought periods accelerate this transition. Indicators include very old sagebrush stands with very little understory between the sagebrush canopy. Bare ground patch sizes are large (>6 foot canopy gaps comprising >30% of transect) and comprise the majority of the interspaces between sagebrush plants.
Mechanism
The driver for transition from the Grazing Resistant State to the Disturbed State (T2-4) is an increase in the disturbance cycle (i.e. drought, mechanical, chemical, biological treatments) and/or continuous high intensity grazing. Examples include pasture corners near gates, calving pastures, and small acreage horse pastures where rotational grazing is not employed combined with sagebrush treatment (mechanical, chemical, or biological). High stocking densities are soil disturbing, and adding sagebrush treatment(s) to this regime results in an increase in the disturbance cycle. A non-grazing influenced example would be a gravel pit.
Removal of shrubs without proper grazing management can lead to an increase in bare ground and erosion of the upper soil horizon, and the site can degrade to the Disturbed State (4). Consequences of this transition are decreased soil fertility, soil erosion, soil crusting, and decrease of soil surface aggregate stability. Indicators of the Disturbed state are a shift in shrub dominance away from sagebrush and toward sprouting shrubs, particularly green rabbitbrush (Chrysothamnus viscidiflorus).
Mechanism
The driver for transition from the Grazing Resistant to the Highly Disturbed State (T2-5) is a topsoil removing event with mechanical equipment. Examples include construction sites, oil and gas activity, and borrow areas.
Mechanism
The drivers for this restoration pathway are mechanical, biological and chemical treatments with only temporary rest or deferment post-treatment. Due to loss of soil fertility, structure, and organic matter, reference community plants are slow to repopulate the site. Success of this restoration is highly dependent upon climatic factors such as drought.
Mechanism
The driver for this transition is multiple sagebrush killing events in rapid succession outside the normal disturbance regime for this site (see Reference State for discussion). It could be mechanical (including shallow disturbances with heavy equipment/construction or a mowing/chaining/harrow type sage treatment), chemical (including 2,4-D or tebuthiuron), or biological (including browse and/or insects). Fire is not usually possible due to lack of understory fuels to carry the fire. In fact, the Bare Ground State is characterized by monotypic decadent sagebrush stands because they are fireproof.
Mechanism
The driver for transition from the Eroded State to the Highly Disturbed State (T3-5) is a topsoil removing event with mechanical equipment. Examples include construction sites, oil and gas activity, and borrow areas.
Mechanism
The driver for transition from the Disturbed State to the Highly Disturbed State (T4-5) is a topsoil removing event with mechanical equipment. Examples include construction sites, oil and gas activity, and borrow areas.
Mechanism
The Highly Disturbed State (5) is often restored to the Grazing Resistant State (2) unintentionally when inappropriate seed mixes are used and post-seeding grazing does not provide adequate and periodic critical growth period rest. There is low potential for recovery without significant inputs of energy and resources if topsoil has been removed. Seed mixes that mimic an adjacent “reference area” rather than the site potential as described in the Reference State (1) will often result in a plant community resembling the Grazing Resistant State (2) due to pre and post-seeding grazing management of the area.
Mechanism
The Highly Disturbed State (5) can transition the Bare Ground State (3) if disturbed areas result in total topsoil removal and are abandoned and climate is favorable for sagebrush seedling establishment. Wyoming big sagebrush will eventually colonize the site, but because soil conditions are severely altered, little to no under-story can be found. An example of this transition can be found on abandoned oil and gas wells that are 30+ years old where topsoil was not stockpiled and re-spread on the site after proper contouring and ripping, and either no seeding was done or the planting was a failure.
Mechanism
The Highly Disturbed State (5) can transition the Disturbed State (4) if disturbed areas result in only partial topsoil removal, leaving rootstock available for sprouting shrubs such as rabbitbrush or shadscale. This is common for gravel pits and areas disturbed as stockpile areas where soil is placed on the area for any amount of time, and then removed with equipment that scrapes some of the soil surface during the removal process.
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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.