Very Shallow

Description

State 1 Narrative:
The Reference State represents non-invaded communities composed of native species. Invasive annual grasses are not present. Very Shallow sites rarely burn, and in most cases, receives minimal grazing. This ecological site is the most stable ecological site on the landscape.

Reference Community 1.1 is one of four classic Very Shallow communities.
Sandberg bluegrass-stiff sagebrush (only in the Channeled Scabland)
Sandberg bluegrass
Sandberg-bluegrass-one-spike oatgrass
Sandberg bluegrass-bluebunch wheatgrass

So, Community 1.1 is mostly very stable. remaining in State 1 regardless of climate or management. Similarity Index scores are typically higher on Very Shallow than other ecological sites on the landscape.

Community 1.2 represents the heavy forb which is caused by heavy grazing to Sandberg bluegrass and quite rare in MLRA 9. The species are native, but Sandberg bluegrass has a diminished presence and forbs are more prominent. Community 1.2 still has enough Sandberg bluegrass present, to shift back to reference community 1.1, given a change in management.

Reference State Community Phases:
1.1 Reference Short grass – low shrub – mid-grass (variations)
1.2 Heavy Forb Forb – low shrub

Dominant Reference State Species:
Sandberg bluegrass in all variations.
One-spike oatgrass, stiff sagebrush or blue bunchgrass on some sites.

At-risk Communities:
• All communities in the reference state are at risk of moving to State 2. The seed source of cheatgrass and/or ventenata is nearby and blowing onto most sites annually
• Community 1.1 has a high cover of Sandberg bluegrass or with one-spike oatgrass, stiff sagebrush or bluebunch wheatgrass, and is thus, at low risk of moving to State 2, Forb-Annual Grass
• Community 1.2 with less Sandberg bluegrass and more forb cover is more at risk of invasion

Submodel

Description

State 2 Narrative:
This state represents a community that is dominated by invasive annual grasses, broadleaf weeds and unpalatable native forbs.

State 2 is quite rare as most Very Shallow sites never cross the threshold into State 2. They stay at climax or near climax condition, as these sites generally receive limited grazing pressure and rarely burn. The situation below has been witnessed on a couple of ridgetops west of Yakima in MLRAs 6 & 8. Chronic heavy grazing in the spring from migrating elk, feral horses or livestock could cause the following:
• Near elimination of Sandberg bluegrass, resulting in
• A plant community dominated almost exclusively by annual forbs &/or annual grasses.
• Annual grasses were rare in the situations witnessed west of Yakima

The amount of ventenata ebbs and flows depending on precipitation. Ventenata is hardly noticeable during years with below to average precipitation but, dominates the site in the years with above average precipitation.

Higher precipitation Very Shallow sites have been altered by heavy grazing pressure and are dominated by ventenata, medusahead, or bulbous bluegrass. Lomatium or another native forb can be prominent as well. A reduction to Sandberg bluegrass cover allows ventenata and other invasive species the opportunity to colonize and invade on a more permanent basis. Heavy grazing use disrupts the soil surface and the moss-lichen layer via animal hooves, which in turn, causes loss of both soil structure and biological crust. When this happens site resistance to erosional forces are greatly diminished.

State 2 will likely have much less or much more pedestaling than the reference condition. Trampling by livestock or game animals can obliterate pedestals and terracettes. Or, erosion in water flow patterns can cause much more pedestaling than reference condition.

Submodel

Description

State 2 Narrative:
This state represents a community that is dominated by invasive annual grasses, broadleaf weeds and unpalatable native forbs.

State 2 is quite rare as most Very Shallow sites never cross the threshold into State 2. They stay at climax or near climax condition, as these sites generally receive limited grazing pressure and rarely burn. The situation below has been witnessed on a couple of
ridgetops west of Yakima in MLRAs 6 & 8. Chronic heavy grazing in the spring from migrating elk, feral horses or livestock could cause the following:
• Near elimination of Sandberg bluegrass, resulting in
• A plant community dominated almost exclusively by annual forbs &/or annual grasses.
• Annual grasses were rare in the situations witnessed west of Yakima

The amount of ventenata ebbs and flows depending on precipitation. Ventenata is hardly noticeable during years with below to average precipitation but, dominates the site in the years with above average precipitation.

Higher precipitation Very Shallow sites have been altered by heavy grazing pressure and are dominated by ventenata, medusahead, or bulbous bluegrass. Lomatium or another native forb can be prominent as well. A reduction to Sandberg bluegrass cover allows ventenata and other invasive species the opportunity to colonize and invade on a more permanent basis. Heavy grazing use disrupts the soil surface and the moss-lichen layer via animal
hooves, which in turn, causes loss of both soil structure and biological crust. When this happens site resistance to erosional forces are greatly diminished.

State 2 will likely have much less or much more pedestaling than the reference condition. Trampling by livestock or game animals can obliterate pedestals and terracettes. Or, erosion in water flow patterns can cause much more pedestaling than reference condition.

Submodel